Deposition technique for producing high quality compound semiconductor materials
Deposited layers are advantageously obtained by utilizing a specific hydride vapor phase epitaxy deposition procedure. In this procedure, a vertical growth cell structure with extended diffusion layer, a homogenising diaphragm, sidewall purging gases, anal independent gas and substrate heaters is used for the deposition of III-V and VI compound semiconductors. This gas flow is uniformly mixed through the extended diffusion layer and directed so that it contacts the full surface of the substrate to produce high quality and uniform films. Exemplary of such gas flow configurations are the positioning of a substrate at a distance from the gas outlets to allow the extended diffusion and a diaphragm placed in a short distance above the substrate to minimize the impact of the convection effect and to improve the uniformity. This symmetrical configuration allows easy scale up from a single wafer to multi-wafer system. This vertical configuration allows the quick switching between different reactive gas precursors so that time modulated growth and etch processes can be employed to further minimize the defects density of the deposited materials.
1. A chemical vapour deposition process for forming a material layer on a surface of a substrate, comprising the use of a cylindrical vertical hydride vapour phase epitaxy (HVPE) growth reactor with an extended diffusion layer, a homogenizing diaphragm, independent side wall gas heater and substrate heater, a reagent gas input, a reagent gas output, a cylindrical side wall gas purging line and a cylindrical side wall gas exit slit, the cylindrical side wall gas purging line being used to purge the reactor during deposition.
2. A process according to claim 1 , where the material layer comprises group III-V and VI materials.
3. A process according to claim 1 , wherein the material layer deposited on the surface of the substrate is provided by a time-modulated growth method, allowing switching between different reactive gases for a controlled growth mode (lateral or vertical) and in situ etching and annealing of deposited material.
4. A process according to claim 1 , wherein the growth reactor uses an opposite direction flow geometry.
5. A process according to claim 1 , wherein the diaphragm has a diameter which is close to the effective diameter of the substrate.
6. A process according to claim 1 , wherein the growth reactor has a mixing chamber and a mixing plate to enhance deposition uniformity.
7. A process according to claim 1 , wherein the extended diffusion layer has a length larger than the effective diameter of the substrate.
8. A process according to claim 1 , where the growth reactor has an in situ gas precursor synthesis region.
9. A process according to claim 1 , wherein the gas heater comprises a multi-zone heating system.
10. A process according to claim 1 , wherein said substrate comprises a member comprising a material chosen from the group consisting of sapphire, silicon carbide, silicon, GaAs, sapphire coated with GaN, MN, ZnO, NdGaO 3 , MgAl 2 O 4 , LiAlO 2 and LiGaO 2 .
11. A process according to claim 1 , wherein the growth reactor is made of at least one of quartz, sapphire, boron nitride, aluminium nitride, silicon carbide, graphite coated with silicon carbide and stainless steel.
12. A process according to claim 1 , wherein the substrate in the growth reactor is rotated using gas purging or a motor.
13. A process according to claim 6 , wherein the mixing plate has holes of diameters less than 1/20 of the effective diameter of the substrate.
14. A process according to claim 6 , wherein the mixing plate is made of at least one of quartz, sapphire, boron nitride, aluminium nitride, silicon carbide and graphite coated with silicon carbide.
15. A process according to claim 6 wherein the mixing plate comprises a perforated or quartz frit mixing plate.
16. A chemical vapour deposition apparatus for forming a material layer on a surface of a substrate, comprising a cylindrical vertical hydride vapour phase epitaxy (HVPE) growth reactor with an extended diffusion layer, a homogenizing diaphragm, independent side wall gas heater and substrate heater, a reagent gas input, a reagent gas output, a cylindrical side wall gas purging line for purging the reactor during deposition and a cylindrical side wall gas exit slit.
17. Apparatus according to claim 16 , wherein the growth reactor uses an opposite direction flow geometry.
18. Apparatus according to claim 16 , wherein the diaphragm has a diameter which is close to the effective diameter of the substrate.
19. Apparatus according to claim 16 , wherein the growth reactor has a mixing chamber and a mixing plate to enhance deposition uniformity.
20. Apparatus according to claim 16 , wherein the extended diffusion layer has a length larger than the effective diameter of the substrate.
21. Apparatus according to claim 16 , where the growth reactor has an in situ gas precursor synthesis region.
22. Apparatus according to claim 16 , wherein the gas heater comprises a multi-zone heating system.
23. Apparatus according to claim 16 , wherein the growth reactor is made of at least one of quartz, sapphire, boron nitride, aluminium nitride, silicon carbide, graphite coated with silicon carbide and stainless steel.
24. Apparatus according to claim 16 , including means for using gas purging or a motor to rotate the substrate in the growth reactor.
25. Apparatus according to claim 19 , wherein the mixing plate is made of at least one of quartz, sapphire, boron nitride, aluminium nitride, silicon carbide and graphite coated with silicon carbide.
26. A chemical vapour deposition process for forming a material layer on a surface of a substrate, comprising the use of a cylindrical vertical hydride vapour phase epitaxy (HVPE) growth reactor with an extended diffusion layer, a homogenizing diaphragm,
independent side wall gas heater and substrate heater, a cylindrical side wall gas purging line and a cylindrical side wall gas exit slit, wherein the growth reactor has a mixing chamber and
a mixing plate to enhance deposition uniformity and the mixing plate comprises a perforated or quartz frit mixing plate.
27. A process according to claim 26 , where the material layer comprises group III-V and VI materials.
28. A process according to claim 26 , wherein the material layer deposited on the surface of the substrate is provided by a time-modulated growth method, allowing switching between different reactive gases for a controlled growth mode (lateral or vertical) and in situ etching and annealing of deposited material.
29. A process according to claim 26 , wherein the growth reactor uses an opposite direction flow geometry.
30. A process according to claim 26 , wherein the diaphragm has a diameter which is close to the effective diameter of the substrate.
31. A process according to claim 26 , wherein the extended diffusion layer has a length larger than the effective diameter of the substrate.
32. A process according to claim 26 , where the growth reactor has an in situ gas precursor synthesis region.
33. A process according to claim 26 , wherein the gas heater comprises a multi-zone heating system.
34. A process according to claim 26 , wherein said substrate comprises a member comprising a material chosen from the group consisting of sapphire, silicon carbide, silicon, GaAs, sapphire coated with GaN, AlN, ZnO, NdGaO 3 , MgAl 2 O 4 , LiAlO 2 and LiGaO 2 .
35. A process according to claim 26 , wherein the growth reactor is made of at least one of quartz, sapphire, boron nitride, aluminium nitride, silicon carbide, graphite coated with silicon carbide and stainless steel.
36. A process according to claim 26 , wherein the substrate in the growth reactor is rotated using gas purging or a motor.
37. A process according to claim 26 , wherein the mixing plate has holes of diameters less than 1/20 of the effective diameter of the substrate.
38. A chemical vapour deposition apparatus for forming a material layer on a surface of a substrate, comprising a cylindrical vertical hydride vapour phase epitaxy (HVPE) growth reactor with an extended diffusion layer, a homogenizing diaphragm, independent side wall gas heater and substrate heater, a cylindrical side wall gas purging line and a cylindrical side wall gas exit slit, wherein the growth reactor has a mixing chamber and a mixing plate to enhance deposition uniformity and the mixing plate comprises a perforated or quartz fit mixing plate.
39. Apparatus according to claim 38 , wherein the growth reactor uses an opposite direction flow geometry.
40. Apparatus according to claim 38 , wherein the diaphragm has a diameter which is close to the effective diameter of the substrate.
41. Apparatus according to claim 38 , wherein the extended diffusion layer has a length larger than the effective diameter of the substrate.
42. Apparatus according to claim 38 , where the growth reactor has an in situ gas precursor synthesis region.
43. Apparatus according to claim 38 , wherein the gas heater comprises a multi-zone heating system.
44. Apparatus according to claim 38 , wherein the growth reactor is made of at least one of quartz, sapphire, boron nitride, aluminium nitride, silicon carbide, graphite coated with silicon carbide and stainless steel.
45. Apparatus according to claim 38 , including means for using gas purging or a motor to rotate the substrate in the growth reactor.
46. Apparatus according to claim 38 , wherein the mixing plate is made of at least one of quartz, sapphire, boron nitride, aluminium nitride, silicon carbide and graphite coated with silicon carbide.