Vapor-phase epitaxial growth method and vapor-phase epitaxy apparatus

Abstract

A vapor phase epitaxial growth method using a vapor phase epitaxy apparatus having a chamber, a support structure holding thereon a substrate in the chamber, a first flow path supplying a reactant gas for film formation on the substrate and a second flow path for exhaust of the gas, said method includes rotating the substrate, supplying the reactant gas and a carrier gas to thereby perform vapor-phase epitaxial growth of a semiconductor film on the substrate, and during the vapor-phase epitaxial growth of the semiconductor film on the substrate, controlling process parameters to make said semiconductor film uniform in thickness, said process parameters including flow rates and concentrations of the reactant gas and the carrier gas, a degree of vacuum within said chamber, a temperature of the substrate, and a rotation speed of said substrate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram schematically showing, in cross-section, a structure of main part of VPE apparatus in accordance with one embodiment of this invention.

FIG. 2 is a diagram showing a perspective view of a VPE system using the apparatus of FIG. 1.

FIG. 3 depicts an exemplary unit configuration of the VPE system using the apparatus.

FIG. 4 is a top plan view of a wafer holder structure supporting thereon a silicon wafer in the FIG. 1 apparatus.

FIG. 5 is a cross-sectional view of the wafer holder of FIG. 4 with the wafer being mounted thereon.

FIG. 6 is an enlarged sectional view of part of the holder along with a peripheral portion of the wafer thereon.

FIG. 7 shows a partial sectional view of a wafer holder of the type having no stepwise recesses and peripheral part of a silicon wafer in the state that an epitaxial film is formed thereon.

FIG. 8 is a partial sectional view of a stepwise recess-formed holder as used in the FIG. 1 apparatus and its corresponding peripheral part of a silicon wafer in the state that an epitaxial film is formed thereon.

FIG. 9 is a top plan view of another exemplary wafer holder with a silicon wafer being situated thereon; and

FIG. 10 is a cross-sectional view of the holder of FIG. 9 supporting thereon the silicon wafer.

FIG. 11 illustrates, in cross-section, a structure of main part of VPE apparatus in accordance with another embodiment of the invention.

FIG. 12 is a top plan view of a wafer holder supporting thereon a silicon wafer in the apparatus of FIG. 11; and

FIG. 13 is a sectional view of the holder and wafer shown in FIG. 12.

FIG. 14 is a top plan view of another exemplary wafer holder with a silicon wafer mounted thereon; and

FIG. 15 is a sectional view of the wafer-supporting holder of FIG. 14.

FIG. 16 is a plan view of still another exemplary wafer holder with a silicon wafer held thereon; and

FIG. 17 is a sectional view of the wafer-supporting holder of FIG. 16.

FIG. 18 is a plan view of yet another exemplary wafer holder with a silicon wafer placed thereon;

FIG. 19 is a sectional view of the wafer holder of FIG. 18; and

FIG. 20 is an enlarged sectional view of part of the wafer holder which has a recess formed therein and its corresponding peripheral portion of the silicon wafer.

FIG. 21 is a plan view of a further exemplary wafer holder with a silicon wafer held thereon;

FIG. 22 is a sectional view of the wafer holder of FIG. 21; and

FIG. 23 is an enlarged sectional view of part of the holder with a recess formed therein and its corresponding portion of the wafer.

FIG. 24 is a plan view of another further exemplary wafer holder having an annular array of wafer-positioning balls and a silicon wafer mounted thereon;

FIG. 25 is a sectional view of the holder of FIG. 24; and

FIG. 26 is an enlarged sectional view of part of the holder which has a ball and its corresponding peripheral portion of the wafer.

FIG. 27 shows a partial sectional view of a wafer holder of the type having no projections and peripheral part of a silicon wafer as held on the holder in the state that an epitaxial film is formed thereon.

FIG. 28A is a partial sectional view of a wafer holder with projections for use in the VPE apparatus and peripheral part of a silicon wafer in the state that an epitaxial film is formed thereon; and FIG. 28B is a corresponding partial plan view thereof.

FIG. 29 is a diagram graphically showing plots of epitaxial film thickness with respect to several film-to-holder contact phenomena.

FIG. 30 is a plan view of a wafer holder for supporting thereon a silicon wafer in accordance with a further embodiment of the invention; and

FIG. 31 is a cross-sectional view of the wafer holder of FIG. 30.

FIG. 32 is a plan view of another exemplary wafer holder for supporting thereon a silicon wafer; and

FIG. 33 is an enlarged perspective view of an inside portion of the wafer holder which has an additional projection in its recess.

FIG. 34 is a plan view of a further example of the holder structure supporting thereon a silicon wafer; and

FIG. 35 is an enlarged perspective view of part of the wafer holder which has an additional projection in its low-level recess.

FIG. 36 is a graph showing curves of epitaxial growth rate versus distance from the center of a wafer at varying temperatures with a wafer rotation speed being fixed at a prespecified value.

FIG. 37 is a graph showing curves of epitaxial growth rate versus distance from wafer center at varying substrate rotation speeds with the substrate temperature fixed.

FIG. 38 is a plan view of a holder structure of the type using standard designs for supporting thereon a silicon wafer; and

FIG. 39 is a sectional view of the wafer holder shown in FIG. 38.

Claims

1. A vapor phase epitaxial growth method using a vapor phase epitaxy apparatus having a chamber, a support structure holding thereon a substrate in the chamber, a first flow path supplying a reactant gas for film formation on the substrate and a second flow path for exhaust of the gas, said method comprising: rotating the substrate;supplying the reactant gas and a carrier gas to thereby perform vapor-phase epitaxial growth of a semiconductor film on the substrate; andduring the vapor-phase epitaxial growth of the semiconductor film on the substrate, controlling process parameters to make said semiconductor film uniform in thickness, said process parameters including flow rates and concentrations of the reactant gas and the carrier gas, a degree of vacuum within said chamber, a temperature of the substrate, and a rotation speed of said substrate.

2. The method according to claim 1, wherein said reactant gas is trichlorosilane whereas said carrier gas is hydrogen, and wherein the trichlorosilane is adjusted to be equal to or less than 8 percent (%) in concentration within said chamber with an internal pressure of said chamber being set at 6.7 to 10.6×104 pascals (Pa) while setting the rotation speed of the substrate to 500 to 1,500 revolutions per minute (rpm) and the temperature of the substrate to 1,100 to 1,140 degrees centigrade (° C.) to thereby cause said semiconductor layer to grow at a growth rate of 8 micrometers per minute (pm/min) or greater, resulting in an in-plane thickness distribution of said semiconductor layer being less than or equal to 0.5%.

3. The method according to claim 2, wherein said support structure has a first recess and a second recess at a bottom of the first recess and wherein said second recess has a depth being less than a thickness of said substrate to thereby uniformize gas flow on said substrate from said first gas flow path whereby the in-plane thickness distribution of said semiconductor layer is within 0.5%.

4. The method according to claim 2, wherein said support structure has a plurality of first raised portions as disposed around the substrate to constrain movement thereof in a substantially horizontal direction being identical to a surface of the substrate and a plurality of second raised portions at surface portions being in contact with said substrate to thereby support said substrate at top faces of the second raised portions and wherein the gases are flown onto said substrate from said first flow path to ensure that the in-plane thickness distribution of said semiconductor layer is within 0.5%.

5. The method according to claim 2, wherein said support structure has a first recess, a second recess at a bottom of the first recess, said second recess having a depth being less than a thickness of the substrate, a plurality of first raised portions as disposed around the substrate to constrain movement thereof in a substantially horizontal direction being identical to a surface of the substrate, and a plurality of second raised portions at surface portions to be in contact with said substrate for holding said substrate at top faces of said second raised portions whereby gas flow on said substrate from said first flow path is made uniform so that the in-plane thickness distribution of said semiconductor layer is within 0.5%.

6. The method according to claim 5, wherein the depth of said first recess is less than the thickness of said substrate.

7. The method according to claim 2, wherein said support structure has a plurality of raised portions disposed around the substrate for constraining its movement in a substantially horizontal direction being identical to a surface of said substrate and a surface for holding said substrate as contacted with a back surface of said substrate.

8. The method according to claim 7, wherein said raised portions extend toward a center of the substrate and are sized so that a length of each raised portion extending toward the center is more than twice a thickness of a film to be formed on the substrate surface by use of the reactant gas.

9. A vapor phase epitaxy apparatus comprising: a chamber with its internal pressure being controlled to range from 6.7 to 10.6×104 Pa when forming a film on the substrate;a flow path supplying a mixture of a trichlorosilane gas and a carrier gas into said chamber while controlling the trichlorosilane to 8% or less in concentration;a support structure holding thereon a substrate within said chamber and being driven to rotate the substrate at a rotation speed of 500 to 1500 rpm during film formation; anda heater operative to control a temperature of the substrate to stay at 1100 to 1140° C. during film formation.

10. The apparatus according to claim 9, wherein said support structure has a plurality of raised portions as disposed around the substrate to constrain movement thereof in a substantially horizontal direction being identical to a surface of said substrate and a surface for holding said substrate as contacted with a back surface of said substrate.

11. The apparatus according to claim 10, wherein said raised portions are rounded at tip ends thereof.

12. The apparatus according to claim 10, wherein said raised portions have spherical tip ends.

13. The apparatus according to claim 9, wherein said support structure has a plurality of first raised portions disposed around the substrate to constrain its movement in a substantially horizontal direction being identical to a surface of the substrate and a plurality of second raised portions provided on a surface to be contacted with the substrate for supporting said substrate at top faces of said second raised portions.

14. The apparatus according to claim 9, wherein said support structure has a first recess and a second recess at a bottom of the first recess and holds said substrate at a bottom face of said second recess.