US20050173705A1 - Fabrication method of semiconductor device and semiconductor device - Google Patents

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• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
  • C23C16/455—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for introducing gases into reaction chamber or for modifying gas flows in reaction chamber
  • C23C16/45502—Flow conditions in reaction chamber
  • C23C16/45506—Turbulent flow
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
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  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
  • C23C16/455—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for introducing gases into reaction chamber or for modifying gas flows in reaction chamber
  • C23C16/45523—Pulsed gas flow or change of composition over time
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
  • C23C16/455—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for introducing gases into reaction chamber or for modifying gas flows in reaction chamber
  • C23C16/45563—Gas nozzles
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
  • C23C16/455—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for introducing gases into reaction chamber or for modifying gas flows in reaction chamber
  • C23C16/45563—Gas nozzles
  • C23C16/45578—Elongated nozzles, tubes with holes
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
  • C23C16/458—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for supporting substrates in the reaction chamber
  • C23C16/4582—Rigid and flat substrates, e.g. plates or discs
  • C23C16/4583—Rigid and flat substrates, e.g. plates or discs the substrate being supported substantially horizontally
  • C23C16/4584—Rigid and flat substrates, e.g. plates or discs the substrate being supported substantially horizontally the substrate being rotated
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
  • C23C16/46—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for heating the substrate
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
  • C30B25/02—Epitaxial-layer growth
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
  • C30B29/10—Inorganic compounds or compositions
  • C30B29/40—AIIIBV compounds wherein A is B, Al, Ga, In or Tl and B is N, P, As, Sb or Bi
  • C30B29/403—AIII-nitrides
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
  • C30B29/10—Inorganic compounds or compositions
  • C30B29/52—Alloys
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/02104—Forming layers
  • H01L21/02365—Forming inorganic semiconducting materials on a substrate
  • H01L21/02436—Intermediate layers between substrates and deposited layers
  • H01L21/02439—Materials
  • H01L21/02441—Group 14 semiconducting materials
  • H01L21/0245—Silicon, silicon germanium, germanium
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/02104—Forming layers
  • H01L21/02365—Forming inorganic semiconducting materials on a substrate
  • H01L21/02518—Deposited layers
  • H01L21/02521—Materials
  • H01L21/02524—Group 14 semiconducting materials
  • H01L21/02532—Silicon, silicon germanium, germanium
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/02104—Forming layers
  • H01L21/02365—Forming inorganic semiconducting materials on a substrate
  • H01L21/02518—Deposited layers
  • H01L21/0257—Doping during depositing
  • H01L21/02573—Conductivity type
  • H01L21/02576—N-type
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/02104—Forming layers
  • H01L21/02365—Forming inorganic semiconducting materials on a substrate
  • H01L21/02518—Deposited layers
  • H01L21/0257—Doping during depositing
  • H01L21/02573—Conductivity type
  • H01L21/02579—P-type
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/02104—Forming layers
  • H01L21/02365—Forming inorganic semiconducting materials on a substrate
  • H01L21/02612—Formation types
  • H01L21/02617—Deposition types
  • H01L21/0262—Reduction or decomposition of gaseous compounds, e.g. CVD
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/28—Manufacture of electrodes on semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/268
  • H01L21/28008—Making conductor-insulator-semiconductor electrodes
  • H01L21/28017—Making conductor-insulator-semiconductor electrodes the insulator being formed after the semiconductor body, the semiconductor being silicon
  • H01L21/28026—Making conductor-insulator-semiconductor electrodes the insulator being formed after the semiconductor body, the semiconductor being silicon characterised by the conductor
  • H01L21/2807—Making conductor-insulator-semiconductor electrodes the insulator being formed after the semiconductor body, the semiconductor being silicon characterised by the conductor the final conductor layer next to the insulator being Si or Ge or C and their alloys except Si
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  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D30/00—Field-effect transistors [FET]
  • H10D30/01—Manufacture or treatment
  • H10D30/021—Manufacture or treatment of FETs having insulated gates [IGFET]
  • H10D30/0223—Manufacture or treatment of FETs having insulated gates [IGFET] having source and drain regions or source and drain extensions self-aligned to sides of the gate
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  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D30/00—Field-effect transistors [FET]
  • H10D30/60—Insulated-gate field-effect transistors [IGFET]
  • H10D30/751—Insulated-gate field-effect transistors [IGFET] having composition variations in the channel regions
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  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
  • H10D30/00—Field-effect transistors [FET]
  • H10D30/60—Insulated-gate field-effect transistors [IGFET]

Definitions

• This invention relates to a fabrication technique of a semiconductor device and a technique for semiconductor device, and more particularly, to a fabrication method of a semiconductor device wherein a silicon germanium film is formed on a semiconductor substrate and also to a technique effective in application to semiconductor devices.
• SiGe silicon-germanium
• a silicon-germanium film and a silicon film are successively, epitaxially formed on a silicon substrate wherein a semiconductor element, such as a MOS transistor, is formed to provide a semiconductor device.
• a film-forming method such as an MBE (molecular beam epitaxy) method or a UHV-CVD (ultrahigh vacuum chemical vapor deposition) method.
• a silicon-germanium film is formed in high vacuum, so that the film-forming apparatus should be provided with an advanced type of vacuum pumping system.
• This requires a large-sized film-forming apparatus, thus increasing the fabrication costs of semiconductor device.
• the forming speed of silicon-germanium film is relatively small. Accordingly, a long time is required for the formation of the silicon-germanium film, thereby increasing the fabrication time of semiconductor device.
• a single wafer CVD method using a laminar flow under atmospheric pressure is used for the forming method of a silicon-germanium film.
• the forming speed of a silicon-germanium film can be made relatively large, a problem on practical application arises in that the productivity of semiconductor device is worsened when a thick film is formed since the condition of single wafer processing is added.
• gases introduced into a processing chamber of the forming apparatus run in the processing chamber as a laminar flow, under which the quality of the silicon-germanium film formed on a semiconductor substrate is unlikely to be improved. This results in the lowering in fabrication yield of the semiconductor device.
• An object of the invention is to provide a fabrication method of a semiconductor device wherein a fabrication time can be shortened, and also such a semiconductor device as mentioned above.
• Another object of the invention is to provide a fabrication method of a semiconductor device wherein a fabrication yield can be improved, and also the thus fabricated semiconductor device.
• a further object of the invention is to provide a fabrication method of a semiconductor device wherein reliability can be improved, and also the thus fabricated semiconductor device.
• a fabrication method of a semiconductor device comprises forming a silicon-germanium film under a pressure within an atmospheric or quasi-atmospheric region by use of a batch-type film-forming apparatus.
• a fabrication method of a semiconductor device comprises introducing gases into a processing chamber of a film-forming apparatus so that turbulence is established, under which a silicon-germanium film is formed.
• a semiconductor device includes a silicon-germanium film formed on a semiconductor substrate wherein a distribution of germanium concentration along the thickness of the film has a peak at an intermediate region of the silicon-germanium film.
• FIG. 1 is a front view showing, partly cut away, a conceptional structure of a semiconductor fabricating apparatus used in a fabrication process of a semiconductor device according to one embodiment of the invention
• FIG. 2 is a top view, partly cut away, of the semiconductor fabricating apparatus of FIG. 1 ;
• FIG. 3 is a side view conceptionally showing a structure in the vicinity of a gas nozzle tip of the semiconductor fabricating apparatus of FIG. 1 ;
• FIG. 4 is a top view of the gas nozzle of FIG. 3 ;
• FIG. 5 is a sectional view of an essential part in the course of the fabrication of the semiconductor device according to the embodiment of the invention.
• FIG. 6 is a sectional view of the essential part in the course of the fabrication of the semiconductor device subsequent to FIG. 5 ;
• FIG. 7 is a sectional view of the essential part in the course of the fabrication of the semiconductor device subsequent to FIG. 6 ;
• FIG. 8 is a sectional view of the essential part in the course of the fabrication of the semiconductor device subsequent to FIG. 7 ;
• FIG. 9 is a sectional view of the essential part in the course of the fabrication of the semiconductor device subsequent to FIG. 8 ;
• FIG. 10 is an illustrative view showing a semiconductor device used in the fabrication process of a semiconductor device according to anther embodiment of the invention.
• FIG. 11 is a sectional view conceptionally showing the state of forming a silicon film on a silicon-germanium film on a semiconductor wafer;
• FIG. 12 is a sectional view of an essential part in the course of the fabrication of a semiconductor device according to a further embodiment of the invention.
• FIG. 13 is a graph showing the temperature of a semiconductor wafer in the steps of forming a silicon-germanium film and a strained silicon film and the flow rate of a monogermane (GeH 4 ) gas introduced into a film-forming apparatus;
• FIG. 14 is a graph showing the temperature of a semiconductor wafer in the steps of forming a silicon-germanium film and a strained silicon film and the flow rate of a monogermane (GeH 4 ) gas introduced into a film-forming apparatus;
• FIG. 15 is a graph showing a distribution of germanium concentration along a depth of a silicon-germanium film
• FIG. 16 is a graph schematically showing a distribution of germanium concentration along a depth of a silicon-germanium film
• FIG. 17 is a graph schematically showing a distribution of germanium concentration along a depth of a silicon-germanium film.
• FIG. 18 is a graph showing the results of measuring of an increase in lattice constant of the strained silicon film formed on the silicon-germanium film.
• FIG. 1 is a front view, partially cut away, of a conceptional structure of a semiconductor fabricating apparatus used in the process of fabricating a semiconductor device according to this embodiment of the invention.
• FIG. 2 is a top view, partly cut away, of the semiconductor fabricating apparatus of FIG. 1 . It will be noted that in FIG. 1 , the cut away portion is shown as a conceptional section.
• a semiconductor fabricating apparatus 1 shown in FIGS. 1 and 2 is a film-forming apparatus which is used in the process of forming a silicon-germanium film and a silicon film on a semiconductor substrate and is, for example, a batch-type CVD apparatus. It will be noted that for ease of understanding, structures other than a processing chamber and the inside thereof of the semiconductor fabricating device 1 are not particularly shown, with their detailed description being omitted.
• the semiconductor fabricating apparatus 1 includes a reaction chamber or processing chamber 2 , a susceptor 3 arranged therein, a susceptor support 4 for supporting the susceptor 3 , a high frequency coil 6 located below the susceptor 3 and accommodated within a coil cover 5 , a gas nozzle 7 for introducing various types of gases into the processing chamber 2 , and a gas exhaust port 8 for discharging a gas from the processing chamber 2 .
• the processing chamber 2 is a hermetically sealable reaction chamber and has a base plate 9 , a bell jar 10 airtightly connected to the base plate 9 via an O ring, and a bell jar purge portion 11 .
• the bell jar 10 is constituted of a quartz bell jar 10 a provided at the inner wall side thereof and a stainless steel bell jar 10 b provided at an outer wall (outer) side thereof, and the stainless steel bell jar 10 b has a viewport 10 c through which the inside of the processing chamber 2 can be visually observed.
• the susceptor 3 is supported with the susceptor support 4 within the processing chamber 2 that is a space surrounded with the base plate 9 and the bell jar 10 , and is so arranged as to be rotatable along a susceptor rotation direction 3 a within the processing chamber 2 .
• the susceptor 3 is made, for example, of carbon with its surface being coated, for example, with silicon carbide (SiC).
• SiC silicon carbide
• the susceptor 3 is so arranged that a plurality of semiconductor wafers (semiconductor substrates) 12 can be disposed thereon.
• the high frequency coil 6 accommodated in the coil cover 5 is so arranged as to be connected to a high frequency power supply not shown, which is provided outside the processing chamber 2 , thereby enabling a high frequency voltage or high frequency power to be applied or supplied to the high frequency coil 6 from the high frequency power supply.
• a high frequency power supply not shown, which is provided outside the processing chamber 2 , thereby enabling a high frequency voltage or high frequency power to be applied or supplied to the high frequency coil 6 from the high frequency power supply.
• the gas nozzle 7 is connected to a gas introducing means, not shown, so that desired types of gases can be introduced into the processing chamber 2 at desired flow rates from the gas nozzle 7 .
• the gas exhaust port 8 is connected to a gas exhaust pipe, not shown, and is thus so arranged that the gases introduced from the gas nozzle 7 into the processing chamber 2 can be discharged. Although only one gas exhaust port 8 is shown in FIG. 2 , another gas exhaust port 8 is also provided at a symmetric position relative to the gas exhaust port 8 shown in the figure. The number of gas exhaust ports 8 may be increased or decreased as required.
• the gas nozzle is disposed as projecting-upwardly substantially from the center of the susceptor 3 and thus, permits gases to be introduced into the processing chamber 2 from above a plurality of semiconductor wafers 12 placed on the susceptor 3 .
• FIG. 3 is a side view conceptionally showing a structure in the vicinity of the tip of the gas nozzle 7
• FIG. 4 is a top view thereof.
• the gas nozzle 7 is formed with a plurality of holes 7 a in the vicinity of the round tip thereof, and desired types of gases are charged or introduced into the processing chamber 2 from individual holes 7 a .
• Each hole 7 a has, for example, a diameter of 4 mm and, for example, nine holes 7 a are formed at different positions of the curved face at the tip of the gas nozzle 7 .
• the holes 7 a face in different directions, so that gases are charged via the holes 7 a of the gas nozzle 7 in plural directions from the inside of the processing chamber 2 toward the inner walls of the processing chamber 2 .
• the gas nozzle may be so arranged as to be rotated within the processing chamber.
• the gas flow introduced or radiated from the holes 7 a of the gas nozzle 7 into the processing chamber 2 has different directions in the processing chamber 2 .
• a gas is charged, as is particularly shown as gas charge directions 13 in FIGS. 1 to 4 , in a horizontal direction (i.e. a direction parallel to the susceptor 3 , or a direction parallel to the main surface of the semiconductor wafer 12 ), in an upper or vertical direction (i.e. a direction vertical to the susceptor 3 , or a direction vertical to the main surface of the semiconductor wafer 12 ) and in arbitrary directions intermediate between the horizontal and vertical directions.
• the velocity of the gas flow from the holes 7 a of the gas nozzle 7 is, for example, at 25 m/seconds.
• the pressure (gas feed pressure) of the gas charged from the gas nozzle 7 is, for example, at about 200,000 Pa (i.e. about 2 kgf/cm 2 ), and thus the gas flow is, for example, at 170 slm (standard liters per minute).
• the gas radiated from the holes 7 a of the gas nozzle 7 collides with the inner walls and the like of the processing chamber 2 . This does not allow the gas introduced into the processing chamber to be in a laminar flow, but causes a turbulence eddy flow.
• a swirl (eddy current) is generated in the gas flow within the processing chamber 2 owing to the turbulence eddy flow.
• This swirl irregularly changes.
• the gas flow, in which the turbulence eddy flow is caused and eddy currents are generated in the flow above the semiconductor wafer 12 is forcedly circulated within the processing chamber 2 .
• the swirl of the gas flow in the processing chamber is not kept constant but irregularly changes. This causes the gas in the processing chamber 2 to be homogenized. In this way, the gas components can be uniformly or homogenizedly stayed over a plurality of semiconductor wafers 12 placed on the susceptor 3 .
• the quality and thickness of the silicon-germanium film or silicon film formed on the semiconductor wafers 12 by a CVD method or the like can be made uniform between the semiconductor wafers 12 and in plane of individual semiconductor wafers 12 .
• the gases which do not contribute to reaction are discharged from the gas exhaust port 8 to outside of the processing chamber 2 . It will be noted that with the case of this embodiment, although gases are charged from the gas nozzle 7 in plural directions, release only in one direction, e.g. in an upper or vertical direction, may be possible.
• FIGS. 5 to 9 are, respectively, a sectional view of an essential part in the course of the fabrication of the semiconductor device according to the embodiment.
• a plurality of semiconductor wafers (semiconductor substrates) 12 made, for example, of a silicon substrate are provided.
• the semiconductor wafer 12 there may be used, for example, a substrate made of silicon single crystal by 4 degrees off from ( 100 ), i.e. a single crystal silicon substrate (silicon wafer) having a main surface inclined by 4 degrees from the plane ( 100 ).
• the semiconductor wafers 12 are transferred to the semiconductor fabricating apparatus 1 wherein the wafers 12 are placed in position on the susceptor 3 .
• High frequency power from a high frequency power supply is applied or supplied to the high frequency coil 6 of the semiconductor fabricating apparatus 1 . Consequently, the susceptor is heated by application of an induction current thereby heating the semiconductor wafers 12 to a predetermined temperature.
• Gases for film formation are introduced from the gas nozzle 7 into the processing chamber 2 .
• a hydrogen gas (H 2 ) used for example, as a carrier gas
• a monosilane (SiH 4 ) gas used for example, as a silicon source gas
• a diborane gas (B 2 H 6 ) gas used for example as a p-type doping gas and diluted with H 2 to a concentration of 30 ppm
• a monogermane (GeH 4 ) gas used for example, as a germanium source gas and diluted with H 2 to a concentration of 1% are, respectively, introduced into the processing chamber 2 .
• the gases introduced into the processing chamber 2 react with each other and deposit on the semiconductor wafer 12 , thereby causing a silicon-germanium film (SiGe film) to be epitaxially grown on the respective semiconductor wafers 12 .
• the processing chamber 2 should preferably be kept at a pressure within atmospheric pressure and quasi-atmospheric pressure regions and more preferably at a pressure within an atmospheric pressure region. More particularly, the pressure within the processing chamber 2 in the course of the film-forming step of a silicon-germanium film should preferably be within a range of from 20,000 to 180,000 Pa (150 to 1,350 Torr.), more preferably from 60,000 to 140,000 Pa (450 to 1050 Torr.) and more preferably from 88,000 to 115,000 Pa (660 to 860 Torr.).
• the pressure within the processing chamber 2 in this embodiment is set at a level higher than those in an MBE apparatus (wherein the pressure within a processing chamber upon forming of a film is within a ultra-high vacuum region of 10 ⁇ 4 to 10 ⁇ 3 ), aUHV-CVD apparatus (wherein the pressure within a processing chamber upon forming of a film is within a high vacuum region of about 0.1 Pa), and a low pressure CVD apparatus (wherein the pressure within a processing chamber upon forming of a film is within a low pressure range of about 10 to 1,000 Pa).
• the growth rate or film-forming rate of the silicon-germanium film can be made higher than those attained by using the MBE apparatus, UHV-CVD apparatus and low pressure CVD apparatus. If the pressure in the processing chamber 2 is within a range of the atmospheric and quasi-atmospheric pressure regions and is smaller than a pressure of outside air, the base plate 9 and the bell jar 10 can be more strongly combined through the O ring.
• a usable silicon source gas includes not only monosilane (SiH 4 ) gas, but also disilane (Si 2 H 6 ) gas, for example.
• a Cl-containing gas such as dichlorosilane (SiH 2 Cl 2 ) gas, trichlorosilane (SiHCl 3 ) gas, silicon tetrachloride (SiCl 4 ) gas or the like.
• HCl gas may be added to those gases mentioned above. This contributes to improving the growth rate of the silicon-germanium film 21 or improving the quality such as by reduction in amount of foreign matters.
• germanium source gas germanium tetrachloride (GeCl 4 ) or Ge 2 H 6 gas may be used in place of GeH 4 gas.
• GeCl 4 germanium tetrachloride
• Ge 2 H 6 gas an N-type doping gas such as phosphine (PH 3 ) gas may be used in place of the P-type doping gas.
• phosphine (PH 3 ) gas may be used in place of the P-type doping gas.
• an N-type silicon-germanium film can be formed on the semiconductor wafers 12 .
• the introduction of the monogermane gas into the processing chamber is stopped, after which gases including hydrogen gas (H 2 ) serving as a carrier gas, monosilane (SiH 4 ) gas serving as a silicon source gas, and B 2 H 6 gas serving as a P-type doping gas are introduced from the gas nozzle 7 into the processing chamber 2 .
• gases including hydrogen gas (H 2 ) serving as a carrier gas, monosilane (SiH 4 ) gas serving as a silicon source gas, and B 2 H 6 gas serving as a P-type doping gas are introduced from the gas nozzle 7 into the processing chamber 2 .
• gases including hydrogen gas (H 2 ) serving as a carrier gas, monosilane (SiH 4 ) gas serving as a silicon source gas, and B 2 H 6 gas serving as a P-type doping gas are introduced from the gas nozzle 7 into the processing chamber 2 .
• the growth of the silicon-germanium film 21 is completed and a silicon film (strained silicon film) 22 is epitaxially
• a so-called strained silicon film 22 is formed on the silicon-germanium film 22 owing to the difference in lattice constant between silicon germanium and silicon.
• the strained silicon film is improved (or increased) with respect to the mobility of electron. Accordingly, with MISFET formed on the strained silicon film 22 , the mobility of electrons moving between source and drain is improved, thereby ensuring the high speed of the resulting semiconductor device as will be described hereinafter.
• the silicon-germanium film 21 and the strained silicon film 22 are epitaxially grown on the respective semiconductor wafers 12 , thereby providing a structure of FIG. 5 .
• a semiconductor element is formed in the respective semiconductor wafers. Although a procedure of forming a semiconductor element in one semiconductor wafer 12 is illustrated herein, a semiconductor element can be formed in a similar way with respect to other semiconductor wafers.
• an impurity may be ion implanted into the main surface of the semiconductor wafer 12 so as to form a well region, if necessary.
• a P-type well region can be formed.
• an impurity such as phosphorus (P) or the like is ion implanted, an N-type well region can be formed.
• a photoresist as a mask, such an impurity can be implanted only into a desired region.
• an element isolation region 23 made of silicon oxide or the like, is formed in the main surface of the semiconductor wafer 21 (i.e. a so-called SiGe epitaxial wafer) wherein the silicon-germanium film 21 and the strained silicon film 22 have been formed, respectively.
• the element isolation region 23 can be formed, for example, by a LOCOS (local oxidation of silicon) method.
• the element isolation region may be formed by burying a silicon oxide film in a groove formed in the main surface of the semiconductor wafer 12 , for example by a STI (shallow trench isolation) method.
• a gate insulating film 24 is formed on the surface of the semiconductor wafer 12 (i.e. the surface of the strained silicon film 22 ).
• the gate insulating film 24 is made, for example, of a thin silicon oxide film and can be formed by thermal oxidation of the semiconductor wafer 12 .
• a silicon-germanium film 25 is formed on the semiconductor wafer 12 .
• the silicon-germanium film 25 can be formed by use of the semiconductor fabricating apparatus 1 substantially in the same manner as the silicon-germanium film 21 .
• the underlying gate insulating film 24 is made of a silicon oxide film, and the silicon-germanium film 25 formed on the gate insulating film 24 is made of a polycrystalline silicon-germanium film.
• the silicon-germanium film 25 which is made of an microcrystalline silicon-germanium film or an amorphous silicon-germanium film, may be formed.
• the silicon-germanium film may be constituted of a microcrystalline silicon-germanium film.
• gases as used in the step of forming the silicon-germanium film 21 may be employed.
• phosphorus is doped in the silicon-germanium film 25 .
• a tungsten silicide (WSi 2 ) film 26 is formed on the silicon-germanium film 25 .
• the silicon-germanium film 25 and the tungsten silicide film 26 are, respectively, subjected to patterning as shown in FIG. 8 , thereby forming a gate electrode 27 made of the silicon-germanium film 25 and the tungsten silicide film 26 .
• TiSi 2 or CoSi 2 may be used.
• an impurity such as, for example, phosphorus (p) is ion implanted into the a region at opposite sides of the gate electrode 27 , thereby forming n-type semiconductor regions (source, drain) 28 .
• an n-channel MISFET 29 is formed.
• the channel region of the MISFET 29 is formed inside the strained silicon film 22 , so that the mobility of the electrons moving between the source and drain (n-type semiconductor regions 28 ) of the MISFET 29 is improved, thereby ensuring the high speed operations of the MISFET 29 .
• an interlayer insulating film 30 is formed over the main surface of the semiconductor wafer 12 .
• the interlayer insulating film 30 can be formed, for example, by depositing a silicon oxide film by a CVD method.
• a photoresist pattern, not shown, formed on the interlayer insulating film 30 is provided as a mask for dry etching the interlayer insulating film 30 to form a through-hole or contact hole 31 over the n-type semiconductor regions 28 and the gate electrode 27 .
• a plug 32 burying the contact hole 31 is formed, for example, of a titanium nitride film and a tungsten film.
• a barrier film or an aluminium alloy film is deposited on the interlayer insulating film 30 and is patterned by use of a photolithographic technique and an etching technique to form a wiring (first wiring layer) 33 .
• An interlayer insulating 34 is formed on the interlayer insulating film 30 so as to cover the wiring 33 therewith.
• a via hole or through-hole is formed in the interlayer insulating film 34 so that part of the wiring 33 is exposed, and a plug burying the through-hole and an upper wiring layer electrically connected to the wiring 33 via the plug are, respectively, formed like the plug 32 and the wiring 33 , followed by dicing into semiconductor device chips, thereby fabricating the semiconductor devices according to this embodiment.
• the number of wiring layers may be appropriately changed depending on the design.
• the silicon-germanium film 21 and the silicon-germanium film 25 are, respectively, formed at a pressure within the atmospheric and quasi-atmospheric pressure regions, the growth rate can be increased.
• the silicon-germanium film 21 and the silicon-germanium film 25 can be, respectively, formed on a plurality of semiconductor wafers 12 at the same time. This leads to the shortage in fabricating time of the semiconductor device. The fabrication costs of the semiconductor device can also be reduced.
• Turbulence is generated in the processing chamber of the semiconductor fabricating apparatus 1 so that the gases in the processing chamber 2 are forcedly circulated, under which the silicon-germanium film 21 and the silicon-germanium film 25 are, respectively, formed. Accordingly, the silicon-germanium film 21 and the silicon-germanium film 25 can be formed as being in wafer-to-wafer uniformity with respect to the quality and thickness of the films. In addition, the quality and thickness of the silicon-germanium film 21 and the silicon-germanium film 25 in the inplane thereof can be made uniform. This results in improved reliability of the semiconductor device. The fabrication yield of the semiconductor device can be improved.
• the pressure within the processing chamber is not set at a level lower than a pressure of outside air, it is not necessary to connect the gas exhaust port 8 to a vacuum pump or the like. Thus, any vacuum pumping system does not become necessary for the semiconductor fabricating apparatus 1 . The fabrication costs of the semiconductor device can be reduced.
• the pressure in the processing chamber 2 which is within the range of the atmospheric and quasi-atmospheric pressure regions, is set at a level lower than a pressure of outside air
• this pressure in the processing pressure is higher than that in a MBE apparatus, a UHV-CVD apparatus or a low pressure CVD apparatus. Accordingly, a pumping system having such a great throughput as used in the MBE apparatus, UHV-CVD apparatus or low pressure CVD apparatus is not necessary.
• a system balancing the introduction of a gas into the processing chamber 2 with the exhaustion of a gas from the processing chamber should favorably be disposed at the exhaustion side.
• n-channel MISFET the instance of the n-channel MISFET has been illustrated hereinabove.
• a polycrystalline silicon-germanium film 25 doped with boron (B) used in place of phosphorus (P) is used as part of the gate electrode 27 .
• the boron-doped polycrystalline silicon-germanium film 25 is improved in boron activity over a boron-doped polycrystalline silicon film.
• the use of the boron-doped polycrystalline silicon-germanium film 25 as the gate electrode 27 contributes to suppressing depletion at the interface between the gate electrode 27 and the gate insulating film 24 . Similar results are obtained when using other types of impurities, e.g.
• FIG. 10 is a view illustrating a semiconductor fabricating apparatus used in the process of fabricating a semiconductor device according to another embodiment of the invention.
• a semiconductor fabricating apparatus 41 shown in FIG. 10 is a film-forming apparatus used in the process of forming a silicon-germanium film or a silicon film on a semiconductor substrate and is a single wafer processing CVD apparatus.
• the structure of the semiconductor fabricating apparatus 41 other than a processing chamber 42 and means or members provided in the inside thereof is not particularly shown with its detailed description being omitted.
• the semiconductor fabricating apparatus 41 is provided with a processing chamber 42 , a susceptor 43 arranged in the processing chamber 42 , a susceptor support 44 for supporting the susceptor 43 , a high frequency coil 46 disposed below the susceptor and accommodated in a coil cover 45 , a gas nozzle 47 through which different types of gases are introduced into the processing chamber 42 , and a gas exhaust port 48 for discharging a gas from the processing chamber.
• the processing chamber is a hermetically sealable reaction chamber and has a base plate 49 and a bell jar 50 which is in hermetically sealable connection with the base plate 49 through an O ring.
• the bell jar 50 has substantially the same arrangement as the bell jar 10 of the first embodiment and is not shown and illustrated in detail herein.
• the susceptor 43 is supported with the susceptor support 44 within the processing chamber 42 which is a kind of space surrounded by the base plate 49 and the bell jar 50 .
• the susceptor 43 is so arranged that a semiconductor wafer (semiconductor substrate) 52 of a large diameter, e.g. a semiconductor wafer 52 whose diameter is 200 mm or over, can be placed on the susceptor 43 .
• the susceptor 43 is made, for example, of carbon with its surface being coated, for example, with silicon carbide (SiC).
• the high frequency coil 46 accommodated in the coil cover 5 is connected to a high frequency power supply, not shown, at outside of the processing chamber 42 so that a high frequency voltage or power can be applied or supplied to the high frequency coil 46 from the high frequency power supply.
• a high frequency power supply not shown
• an induction current generates in the susceptor 43 whose inside is made of carbon. In this way, the semiconductor wafer 52 placed on the susceptor 43 can be heated to a desired temperature.
• a gas nozzle 47 is connected to a gas introducing means not shown, so that desired types of gases can be introduced from the gas nozzle 47 into the processing chamber 42 at a desired flow rate.
• a gas exhaust port 48 is connected to a gas exhaust pipe not shown, and the gases introduced from the gas nozzle 47 into the processing chamber 42 can be discharged.
• the gas nozzle 47 is disposed at the upper portion of the processing chamber 42 and arranged in such a way that desired types of gases are introduced into the processing chamber 42 above the semiconductor wafer 52 arranged on the susceptor 43 .
• the gas nozzle 47 is bifurcated to provide two tip portions.
• a plurality of holes (not shown) are formed at individual two tip portions of the gas nozzle 47 , like the case of the tip portion of the gas nozzle 7 in Embodiment 1. Desired types of gases are charged or introduced into the processing gas 42 from individual holes.
• the gas nozzle 47 has the holes formed at different positions of the curved surface of the tip portion thereof.
• the gas nozzle may not have a bifurcated arrangement, but may be trifurcated or more.
• the gas nozzle 47 may be so arranged as to be rotated in the processing chamber 42 .
• gases for film formation are released or radiated as being directed from the inside of the processing chamber 47 via the holes of the gas nozzle 47 toward the inner walls of the processing chamber 42 .
• the gas is emitted from the gas nozzle 47 in a horizontal direction (i.e. a direction parallel to the susceptor 43 , or a direction parallel to the main surface of the semiconductor wafer 52 ), in an upper or vertical direction (i.e. a direction vertical to the susceptor 3 , or a direction vertical to the main surface of the semiconductor wafer 12 ) and in arbitrary directions intermediate between the horizontal and vertical directions.
• the gas emitted from the holes of the gas nozzles 47 into the processing chamber is such that a turbulence eddy flow is caused within the processing chamber, like Embodiment 1, and eddy currents are generated in the gas flow above the semiconductor wafer.
• the eddy currents in the gas flow within the processing chamber 42 are not kept uniform but change irregularly. In this manner, the gas is forcedly circulated within the processing chamber, so that the silicon-germanium film or silicon film formed on the semiconductor wafer can be made uniform in the inplane of the semiconductor wafer 52 with respect to the quality and thickness thereof.
• the gas is emitted from the gas nozzle 47 in plural directions according to this embodiment, it may be emitted in one direction, e.g. in an upper or vertical direction alone.
• the fabricating process of a semiconductor device using the semiconductor device fabricating apparatus 41 is similar to that of Embodiment 1 except that semiconductor wafers 52 are subjected to film formation of a silicon-germanium film by use of the semiconductor fabricating apparatus 41 one by one and is not repeatedly illustrated herein.
• a silicon-germanium film is formed on a semiconductor wafer 52 of large diameter (e.g. a diameter of 20 mm or over) by use of a single wafer processing, the film-forming rate of the silicon-germanium film can be improved, and uniform thickness and quality of the film are ensured.
• a semiconductor fabricating apparatus having a plurality of processing chambers may be arranged.
• FIG. 11 is a sectional view conceptionally showing the state wherein a silicon-germanium film 61 and a silicon film (strained silicon film) 62 are, respectively, formed on a semiconductor wafer (semiconductor substrate) 60 .
• the lattice constant of silicon-germanium increases with an increasing concentration of germanium. Accordingly, where the silicon-germanium film 61 is formed on the semiconductor wafer 60 made of single crystal silicon, the epitaxial growth of a silicon-germanium film having a great concentration of germanium on the semiconductor wafer 60 incurs the possibility of causing inconveniences to occur in such a way that the silicon-germanium film is greatly strained owing the difference in lattice constant thereby causing defects of high density to be formed in the silicon-germanium film.
• the concentration of germanium in the silicon-germanium film 61 is made relatively small in the vicinity of the interface between the semiconductor wafer 60 and the silicon-germanium film 61 , so that the lattice constant matching at the interface between the semiconductor wafer 60 and the silicon-germanium film 61 is likely to occur.
• the concentration of germanium increases, for example, in a stepwise manner so that stress is gradually applied thereto.
• the silicon-germanium film 61 is so formed that the concentration of germanium is kept constant (forward step graded process).
• the silicon film (strained silicon film) 62 is epitaxially grown on the silicon-germanium film 61 , the silicon film 62 formed on the underlying silicon-germanium film is strained (i.e. the film is expanded over the lattice constant of ordinary silicon) depending on the lattice constant of the underlying silicon-germanium film 61 .
• the strained silicon film 62 is relatively thin (e.g. 40 to 50 nm), so that few dislocations occur in the strained silicon film 62 .
• the fabricating method of a semiconductor device i.e. a process of forming a silicon-germanium film and a silicon film (strained silicon film) on a semiconductor substrate, is illustrated.
• FIG. 12 is a sectional view of an essential part in the course of fabrication of a semiconductor device according to the embodiment wherein a silicon-germanium film (SiGe film) 71 and a silicon film (strained silicon film) 72 are formed on a semiconductor wafer (semiconductor substrate) 70 .
• FIG. 13 is a graph showing the variations in the temperature of the semiconductor wafer 70 in the formation process of the silicon-germanium film 71 and the silicon film 72 and also in the flow rate of a monogermane (GeH 4 ) gas introduced into a film-forming apparatus.
• the ordinates indicate the temperature of the semiconductor wafer and the flow rate of the monogermane (GeH 4 ) gas, respectively.
• the abscissa in the graph of FIG. 13 indicates time, in which attention should be paid to the fact that the time is expressed in terms of an arbitrary unit and the respective time intervals of times t 1 to t 17 are not set constantly.
• the semiconductor wafer (semiconductor substrate) 70 is transferred to a film-forming apparatus.
• a semiconductor fabricating apparatus 1 or 41 as used hereinbefore is provided as the film-forming apparatus and a silicon-germanium film and a silicon film (strained silicon film) are epitaxially grown in a pressure within a range of atmospheric and quasi-atmospheric regions. This is because the silicon-germanium film and strained silicon film can be, respectively, formed on a plurality of semiconductor wafers within a short time, or the film-forming rate can be improved.
• film-forming apparatus such as a low pressure CVD apparatus or a UHV-CVD method may be used so that a silicon-germanium film and a strained silicon film can be epitaxially grown on the semiconductor wafer 70 under vacuum.
• a low pressure CVD apparatus or a UHV-CVD method
• a silicon-germanium film and a strained silicon film can be epitaxially grown on the semiconductor wafer 70 under vacuum.
• the case using the semiconductor fabricating apparatus 1 is illustrated herein.
• a 4 degrees off ( 100 ) plane substrate made, for example, of silicon single crystal, i.e. a single crystal silicon substrate having a main surface inclined by 4 degrees from the ( 100 ) plane of silicon can be used.
• Nitrogen (N 2 ) gas is introduced into a processing chamber 2 of the semiconductor fabricating apparatus 1 , in which the semiconductor wafers 70 are arranged in position at a flow rate, for example, of 150 slm (standard liters per minute) to well purge air from the processing chamber. In doing so, the reaction between air and hydrogen gas introduced hereinafter can be prevented.
• a flow rate for example, of 150 slm (standard liters per minute) to well purge air from the processing chamber.
• the gas flow rate used herein means a gas flow rate calibrated in terms of 0° C. and 1 atmospheric pressure.
• the introduction of nitrogen gas is stopped at time of t 1 , and hydrogen (H 2 ) gas serving as a carrier gas is introduced into the processing chamber 2 at a flow rate, for example, of 170 slm. It will be noted that the introducing of hydrogen gas is continued up to time of t 17 .
• the temperature of the semiconductor wafer 70 is lowered, for example, to 980° C. over a period of t 4 to t 5 .
• a monosilane (SiH 4 ) gas is further introduced, aside from the hydrogen gas, into the processing chamber 2 over a period of t 5 to t 6 (for example, about one minute), for example, at a flow rate of 40 sccm (standard cubic centimeters per minute).
• t 5 to t 6 for example, about one minute
• 40 sccm standard cubic centimeters per minute
• a monosilane (SiH 4 ) gas serving as a silicon source gas, a diborane (B 2 H 6 ) gas serving as a P-type doping gas and a monogermane (GeH 4 ) gas serving as a germanium source gas are introduced, aside from the hydrogen gas serving as a carrier gas, into the processing chamber 2 at flow rates, for example, of 20 sccm, 60 sccm and 80 sccm, respectively.
• the flow rate of the germane gas is relative low, so that the silicon-germanium film 71 formed at this stage has a relatively low concentration of germanium.
• the monosilane (SiH 4 ) gas and the diborane (B 2 H 6 ) gas are continuedly introduced up to time of t 14 so that the respective flow rates are kept constant, for example.
• the flow rate of the monogermane gas introduced into the processing chamber 2 is increased, for example, to 170 sccm at time of t 8 .
• the flow rates of the monogermane gas introduced into the processing chamber at times of t 9 , t 10 and t 11 are sequentially increased, for example, to 420 sccm, 1050 sccm and 3000 sccm.
• the concentration of germanium in the silicon-germanium film 71 increase correspondingly to the increase in flow rate of the monogermane gas.
• the flow rate of the monogermane gas introduced into the processing chamber 22 is lower, for example, to 2100 sccm at time of t 12 .
• the concentration of germanium in the silicon-germanium film 71 formed over a period of t 12 to t 13 becomes lower than that in the silicon germanium film 71 formed over a period of t 11 to t 12 (at which the flow rate of the monogermane gas is at 3000 sccm).
• the introduction of the monogermane gas into the processing chamber at time of t 13 is stopped (although the introduction of the monosilane gas and the diborane gas is continued).
• the epitaxial growth of the silicon-germanium film is completed, and a silicon film (strained silicon film) 72 is epitaxially grown on the silicon-germanium film 71 .
• the thickness of the silicon-germanium film 71 formed over a period of t 7 to t 13 is, for example, at about 3 to 4 ⁇ m.
• the thickness of the strained silicon film 72 formed on the silicon-germanium film 71 at a period of t 13 to t 14 is, for example, at about 40 to 50 nm.
• FIG. 12 shows the state where the silicon-germanium film 71 and the silicon film (strained silicon film) 72 are formed on the semiconductor wafer 70 in this manner. The thus removed semiconductor wafer 70 is fed to a next fabrication step to form a semiconductor element in the semiconductor wafer 70 .
• the flow rate of the monogermane gas is increased or decreased in a stepwise manner over the period of t 7 to t 12 as is particularly shown in the graph of FIG. 13
• the flow rate of the monogermane gas may be continuously increased or decreased over the period of t 7 to t 12 .
• FIG. 15 is a graph showing a distribution of germanium concentration along the thickness of the silicon-germanium film 71 formed according to this embodiment, and the results (found values) obtained by analysis through a SIMS (secondary ion mass spectroscopy) are shown.
• the abscissa indicates a distance (depth) along the depth from the surface of the strained silicon film, and the ordinate indicates a concentration of germanium (i.e. Ge concentration).
• the concentration of germanium along the thickness of the silicon-germanium film 71 increases in a stepwise manner from the interface (i.e. an interface between the silicon-germanium film 71 and the semiconductor wafer 70 or the silicon film 70 a ) at the side of the semiconductor wafer (semiconductor substrate) 70 of the silicon-germanium film 71 toward the inward direction of the silicon-germanium film 71 , a maximum value or a peak appears at an intermediate region with respect to the thickness of the silicon-germanium film 71 , after which the concentration decreases.
• the germanium concentration in the silicon-germanium film 71 depends on the flow rate of a germanium source gas used in the film-forming step, particularly, a monogermane gas (GeH 4 ) herein.
• a germanium source gas used in the film-forming step
• This concentration-increasing region and neighborhood thereof is referred to as forward step graded region
• the flow rate of the monogermane gas is sequentially increased in a stepwise manner in the order of 80 sccm, 170 sccm, 420 sccm, 1050 sccm and 3000 sccm.
• the region of the silicon-germanium film 71 where the concentration of germanium becomes maximal or a peak corresponds to a film-forming stage (time period of t 11 to t 12 ) where the flow rate of the monogermane gas in the course of the film-forming step of the silicon-germanium film 71 is maximized (at 3000 sccm).
• the interface between the silicon-germanium film 71 and the strained silicon film 72 ) at the strained silicon film 72 side of the silicon-germanium film 71 after the establishment of a peak concentration of germanium in the silicon-germanium film 71 (this concentration decreasing region and the neighborhood thereof are refereed to as reverse step graded region) is that the flow rate of the monogermane gas is lowered from 3000 sccm to 2100 sccm in the film-forming step of the silicon-germanium film 71 . After the flow rate of the monogermane gas is maintained at 2100 sccm over the time period of t 12 to t 13 , the introduction of the monogermane is stopped.
• the concentration of germanium in the silicon-germanium film 71 once decreases from the peak in the reverse step graded region, after which the concentration is kept substantially constant in the vicinity of the interface between the silicon-germanium film 71 and the strained silicon film 72 .
• the region where the concentration of germanium rapidly decreases in a region of the strained silicon film 72 defined at a distance of several tens of nanometers from the surface thereof corresponds to a strained silicon film 72 -forming region.
• FIG. 16 is a graph schematically showing the distribution of germanium concentration along the thickness of the silicon-germanium film 71 in case where the silicon-germanium film is formed according to this embodiment and corresponds to FIG. 15 .
• FIG. 17 is a graph schematically showing the distribution of germanium concentration along the thickness of the silicon-germanium film 71 in case where the silicon-germanium film 71 is formed while continuously increasing or decreasing the flow rate of the monogermane gas as in FIG. 14 .
• the abscissa in FIGS. 16 and 17 indicates a distance (depth) from the surface of the strained silicon film 72 along the depth thereof.
• the ordinate in FIGS. 16 and 17 indicates a concentration of germanium (Ge concentration).
• the germanium concentration Y 1 in the silicon-germanium film 71 in the vicinity of the interface between the silicon-germanium film 71 and the strained silicon film 72 preferably ranges from 5 to 40% (atomic %), more preferably from 10 to 30% (atomic %) and most preferably from 15 to 25% (atomic %).
• the strained silicon film 72 can be appropriately formed on the silicon-germanium film 71 as having an optimum lattice constant ensuring an improved mobility of electron, thereby making it possible to fabricate a high-speed semiconductor device.
• the difference between the peak value Y 2 of the germanium concentration in the silicon-germanium film 71 and the germanium concentration Y 1 , i.e. Y 2 ⁇ Y 1 , should preferably be in the range of from 1 to 40% (atomic %), more preferably from 3 to 20% (atomic %) and most preferably from 5 to 10% (atomic %).
• the ratio of the peak value Y 2 of the germanium concentration in the silicon-germanium film 71 to the germanium concentration Y 1 , i.e. Y 2 /Y 1 should preferably be in the range of from 1.02 to 9.0, more preferably from 1.1 to 3.0 and most preferably from 1.2 to 1.7.
• this permits the strain or stress in the silicon-germanium film 71 to be mitigated, thereby forming the silicon-germanium film 71 and the strained silicon film 72 wherein crystal defects are suppressed from occurring.
• a semiconductor device having high reliability and high performance can be realized.
• a thickness T 1 of the region where the concentration of germanium is changed, or is decreased or increased is, for example, in the range of about 1.5 to 2 ⁇ m.
• a thickness T 2 of the region where the concentration of germanium in the silicon-germanium film 71 is uniform is, for example, in the range of about 1.5 to 2 ⁇ m.
• the intervals of the steps where the concentration of germanium is changed in a stepwise manner are, for example, in the range of about 0.3 to 0.5 ⁇ m.
• a maximum through dislocation density of the silicon-germanium film 71 was measured.
• the maximum through dislocation density was determined by selectively etching the semiconductor wafer (semiconductor substrate) 70 forming the silicon-germanium film 71 and the strained silicon film 72 thereon and observing the surface via a metallurgical microscope.
• the maximum through dislocation density of the silicon-germanium film 71 formed according to the embodiment was found to be at about 1 ⁇ 10 4 cm ⁇ 2.
• a silicon-germanium film was formed by increasing the concentration of germanium from an initial stage of formation of the silicon-germanium film in a stepwise manner, and keeping a constant concentration of germanium without reduction in concentration after the concentration of germanium arrived at a maximum value (i.e. with the case of the silicon-germanium film 61 ), followed by measurement of a maximum through dislocation density.
• the maximum through dislocation density was found to be at about 1 ⁇ 10 6 cm ⁇ 2.
• the maximum through dislocation density can be made small according to the embodiment of the invention wherein the concentration of germanium is increased in a stepwise manner from an initial stage of forming the silicon-germanium film and the silicon-germanium film 71 is formed by once reducing the concentration of germanium after arrival of the concentration of germanium at a maximum value.
• This enables one to reduce the defect density in the silicon-germanium film 71 and the strained silicon film 72 formed thereof. This leads to an improvement in reliability of the resulting semiconductor device.
• the concentration of germanium along the thickness of silicon-germanium film 71 is gradually increased from the interface at the semiconductor wafer (semiconductor substrate) 70 side toward the inner direction of the silicon-germanium film 71 , the stress in the silicon-germanium film 71 is applied in the same direction and thus, is accumulated.
• the concentration of germanium is lowered after the concentration arrives at a peak, the stress accumulated in the forward step graded region can be mitigated in the vicinity of the reverse step graded region. This enables the defects of the silicon-germanium film 71 to be reduced in number in the vicinity of the interface between the silicon-germanium film 71 and the strained silicon film 72 .
• the strained silicon film 72 can be epitaxially grown on the underlying silicon-germanium film 71 having a reduced number of defects.
• the defects in the strained silicon film 72 can be suppressed from occurring.
• such an effect as set forth hereinabove may be likewise obtained in the case where after the concentration of germanium in the silicon-germanium film 71 reaches a peak, the concentration of germanium is reduced in a stepwise manner in the direction of the interface between the silicon-germanium film 71 and the strained silicon film 72 (corresponding to the case of the distribution of germanium concentration in FIG. 16 ) or the concentration is continuously reduced (corresponding to the case of the distribution of germanium concentration in FIG. 17 ).
• the surface roughness of the semiconductor wafer (semiconductor substrate) 70 forming the silicon-germanium film 71 thereon according this embodiment was measured.
• the silicon-germanium film 71 and the strained silicon film 72 were formed on the semiconductor wafer 70 , respectively, followed by measurement of the roughness of the surface (i.e. the surface of the strained silicon film) according to AFM (atomic force microscopy) to calculate a RMS (root mean square) value of the surface roughness.
• the surface roughness of the thin strained silicon film 72 depends on the surface roughness of the underlying silicon-germanium film 71 .
• the RMS value of the surface roughness was found to be at 3.6 nm.
• the film-forming temperature for the silicon-germanium film 71 was at 800° C.
• the RMS value of the surface roughness was found to be at 2.5 nm.
• the RMS value of the surface roughness was measured with respect to the case wherein the silicon-germanium film was formed in such a way that the concentration of germanium was increased in a stepwise manner from an initial state of formation of the silicon-germanium film and after the concentration of germanium reached a maximum value, the concentration of germanium was kept constant without reduction in the concentration (i.e. the case of the silicon-germanium film 61 ).
• the film-forming temperature of the silicon-germanium film 61 was at 777° C.
• the RMS value of the surface roughness was found to be at 4.1 nm.
• the surface roughness can be made small by forming the silicon-germanium film 71 in such a way that the concentration of germanium is increased in a stepwise manner from an initial stage of forming the silicon-germanium film and after the concentration of germanium reaches a maximum value, the concentration of germanium is once reduced.
• the surface roughnesses of the silicon-germanium film 71 and the strained silicon film 72 formed thereon can be made small, respectively, thereby ensuring an improvement in reliability of the semiconductor device.
• the fabrication yield of the semiconductor device can also be improved.
• the surface roughness can be made smaller.
• Such an effect as set forth hereinabove may be likewise obtained in the case where after the concentration of germanium in the silicon-germanium film 71 reaches a peak, the concentration of germanium is reduced in a stepwise manner in the direction of the interface between the silicon-germanium film 71 and the strained silicon film 72 (corresponding to the case of the distribution of germanium concentration in FIG. 16 ) or the concentration is continuously reduced (corresponding to the case of the distribution of germanium concentration in FIG. 17 ).
• FIG. 18 is a graph showing the results of measurement of an increase in lattice constant of the strained silicon film 72 formed on the silicon-germanium film 71 formed according to this embodiment.
• the abscissa of the graph of FIG. 18 indicates a concentration of germanium (i.e. Y 1 in the graphs of FIGS. 16 and 17 ) in the silicon-germanium film 71 in the vicinity of the interface between the silicon-germanium film 71 and the strained silicon film 72 .
• the ordinate of the graph of FIG. 18 indicates an increase in lattice constant of the strained silicon film 7 along xy direction (i.e.
• the solid circle in the graph of FIG. 18 corresponds to a found value of lattice constant of the strained silicon film 72 , and the straight line in the graph indicates the theoretical value (upon mitigation of a cubic strain) showing the relation between the lattice constant of silicon-germanium and the concentration of germanium.
• the found value of lattice constant of the strained silicon film 72 is substantially in coincidence with the theoretical line showing the relation between the lattice constant of silicon-germanium and the concentration of germanium. More particularly, the strained silicon film 72 has an increased (or strained) lattice constant correspondingly to the lattice constant of the underlying silicon-germanium film 71 . Thus, it can be confirmed that the strained silicon film 72 formed according to the embodiment has a strain corresponding to the concentration of germanium (Y 1 ) in the underlying silicon-germanium film 71 and thus, the silicon-germanium film 71 is satisfactorily mitigated with respect to the strain thereof.
• the processing procedure of the semiconductor wafer (semiconductor substrate) 70 prior to the formation of the silicon-germanium film 71 is described. It is preferred that after the following process, the silicon-germanium film 71 is epitaxially grown on the semiconductor wafer 70 .
• the following processing procedures can also be used as a processing procedure of the semiconductor wafer (semiconductor substrate) 12 prior to the formation of the silicon-germanium film 21 in Embodiment 1 wherein it is as a matter of course that the silicon-germanium film 21 should preferably be epitaxially grown on the semiconductor wafer 12 after the processing thereof.
• the semiconductor wafer 70 is heated, for example, to 1040° C. (pre-heating treatment) in a reductive atmosphere such as of hydrogen gas to remove a native oxide film from the surface of the semiconductor wafer 70 , thereby cleaning the surface of the semiconductor wafer 70 .
• a reductive atmosphere such as of hydrogen gas
• a monosilane gas (SiH 4 ) may be introduced into the processing chamber 2 and the semiconductor wafer 70 is heated, for example, at 980° C. so that a thin silicon film 70 a is epitaxially grown on the semiconductor wafer 70 , thereby ensuring the formation of a clean silicon surface.
• this treatment is carried out.
• a hydrogen chloride (HCl) gas may be introduced into the processing chamber 2 and the semiconductor wafer 70 is heated, for example, at 900° C. to etch the surface of the semiconductor wafer 70 , thereby removing the native oxide film from the surface of the semiconductor wafer 70 .
• This step is especially effective in the case where the temperature of the semiconductor wafer 70 is suppressed to a level of 1000° C. or below.
• a hydrogen chloride gas may be introduced into the processing chamber 2 as set out above to etch the surface of the semiconductor wafer 70 .
• a hydrogen chloride gas may be introduced into the processing chamber 2 to etch the surface of the semiconductor wafer 70 , followed by epitaxial growth of the thin silicon film 70 a on the semiconductor wafer 70 as set out hereinabove.
• these surface processing procedures have been described with respect to the formation of the silicon-germanium film 71 on the semiconductor wafer 70 , these procedures are also effective as a surface processing procedure upon further formation of a silicon-germanium film or a silicon film on the silicon-germanium film 71 which has been formed on the semiconductor wafer 70 . Moreover, these procedures are also effective as a surface processing procedure upon further formation of a silicon-germanium film or a silicon film after polishing the surface of the silicon-germanium film 71 , for example, by CMP (chemical mechanical polishing).
• CMP chemical mechanical polishing
• SiH 4 a monosilane (SiH 4 ) gas
• SiH 2 Cl 2 gas may be used as a silicon source gas in place of the SiH 4 gas. This makes it possible to improve the growing rates of the silicon-germanium film 71 and the strained silicon film 72 or suppress the occurrence of foreign matters.
• a SiGH 2 Cl 2 gas may be initially used as a silicon source gas and replaced by a monosilane (SiH 4 ) gas for use as a silicon source gas at a final stage of forming the silicon-germanium film 71 (for example, over final several minutes during a period of t 12 to t 13 in the graph of FIG. 13 ) and also at a film-forming stage (over a period of t 13 to t 14 ) of the strained silicon film 72 .
• a monosilane (SiH 4 ) gas for use as a silicon source gas at a final stage of forming the silicon-germanium film 71 (for example, over final several minutes during a period of t 12 to t 13 in the graph of FIG. 13 ) and also at a film-forming stage (over a period of t 13 to t 14 ) of the strained silicon film 72 .
• a monosilane gas only for the formation of the strained silicon film 72 is also effective.
• semiconductor devices having MISFET have been described, to which the invention is not limited.
• the invention may be applied to a fabricating method of various types of semiconductor devices having a silicon-germanium film formed therein and also to such semiconductor devices.
• a SiGe film can be selectively formed as a base portion of a bipolar element.
• the film-forming rate of the silicon-germanium film can be increased by forming a silicon-germanium film under a pressure within an atmospheric pressure and quasi-atmospheric pressure region.
• the fabricating time of a semiconductor device can be shortened by forming the silicon-germanium film by use of a batch-type film-forming apparatus.
• the silicon-germanium film can be made uniform with respect to the quality and thickness thereof by forming the silicon-germanium film while causing a turbulence of gases for film formation introduced into a processing chamber of a film-forming apparatus.
• the defects in the silicon-germanium film can be reduced in number and the film surface can be more flattened by controlling a distribution of germanium concentration along the thickness of the silicon-germanium film epitaxially grown on a semiconductor substrate to have a peak in an intermediate region along the thickness of the silicon-germanium film.

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