Method of forming semiconducting materials and barriers using a multiple chamber arrangement

• US 5,470,784 A
• Filed: 09/23/1992
• Issued: 11/28/1995
• Est. Priority Date: 12/05/1977
• Status: Expired due to Term

• Current Assignee: Plasma Physics Corporation
• Original Assignee: Plasma Physics Corporation
• Inventors: Coleman, John H.
• Primary Examiner(s): BRENEMAN, ROBERT B
• Assistant Examiner(s): Everhart, Byron
• Application Number:
  US07/949,753
• Time in Patent Office: 1,161 Days
• Field of Search: 437/101, 437/113, 437/173, 118/719, 427/569
• US Class Current: 438/61
• CPC Class Codes: C23C 16/503 using dc or ac discharges
• CPC Class Codes: C23C 16/509 using internal electrodes
• CPC Class Codes: H01J 37/32541 Shape
• CPC Class Codes: H01J 37/32623 Mechanical discharge control means
• CPC Class Codes: H01L 31/074 comprising a heterojunction with an element of Group IV of the Periodic Table, e.g. ITO/Si, GaAs/Si or CdTe/Si solar cells
• CPC Class Codes: H01L 31/075 the potential barriers being only of the PIN type, e.g. amorphous silicon PIN solar cells
• CPC Class Codes: H01L 31/20 such devices or parts thereof comprising amorphous semiconductor materials
• CPC Class Codes: H01L 31/202 including only elements of Group IV of the Periodic Table
• CPC Class Codes: Y02E 10/548 Amorphous silicon PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10S 438/907 Continuous processing

Abstract

In a gaseous glow-discharge process for coating a substrate with semiconductor material, a variable electric field in the region of the substrate and the pressure of the gaseous material are controlled to produce a uniform coating having useful semiconducting properties. Electrodes having concave and cylindrical configurations are used to produce a spacially varying electric field. Twin electrodes are used to enable the use of an AC power supply and collect a substantial part of the coating on the substrate. Solid semiconductor material is evaporated and sputtered into the glow discharge to control the discharge and improve the coating. Schottky barrier and solar cell structures are fabricated from the semiconductor coating. Activated nitrogen species is used to increase the barrier height of Schottky barriers.

Claims

1. A process for glow discharge deposition in an apparatus comprising, a first deposition chamber adapted to be evacuated, first gas introducing means for introducing a first gaseous material into said first deposition chamber, first electrode means disposed in said first deposition chamber, a second deposition chamber adapted to be evacuated, second gas introducing means for introducing a second gaseous material into said second deposition chamber, second electrode means disposed in said second deposition chamber, restricting means for restricting the flow of at least one of said gaseous materials from one of said deposition chambers into the other one of said deposition chamber, said restricting means being disposed between said first deposition chamber and said second deposition chamber, and transporting means for transporting said substrate from one of said deposition chambers to the other one of said deposition chambers through said restricting means, said process comprising the steps of:

disposing said substrate in said first deposition chamber;

introducing said first gaseous material in said first deposition chamber and applying a first electric field to a first region in said first deposition chamber by said first electrode so as to generate a first glow discharge, whereby a first layer is deposited on said substrate;

transporting said substrate on which said first layer is deposited from said first deposition chamber to said second deposition chamber through said restricting means, while each interior of said deposition chambers is shielded from an external atmosphere;

disposing said substrate on which said first layer is deposited in said second deposition chamber; and

introducing said second gaseous material in said second deposition chamber and applying a second electric field to a second region in said second deposition chamber by said second electrode so as to generate a second glow discharge, whereby a second layer is deposited on said first layer.

2. A process according to claim 1 wherein said first gaseous material comprises dopant gas and wherein said second gaseous material comprises a silane gas.

3. A process according to claim 2 wherein said dopant gas comprises phosphorus.

4. A process according to claim 1 wherein said first layer is a semiconductor layer comprising silicon and dopant and wherein said second layer is an intrinsic semiconductor layer comprising silicon.

5. A process according to claim 4 wherein said semiconductor layer comprises phosphorus and wherein said intrinsic semiconductor layer comprises hydrogenated amorphous silicon.

6. A process according to claim 1 wherein said first gaseous material comprises silicon and wherein said second gaseous material comprises nitrogen.

7. A process according to claim 1 wherein said first layer is a semiconductor layer comprising silicon and wherein said second layer comprises nitrogen.

8. A process according to claim 7 wherein said semiconductor layer comprises hydrogenated amorphous silicon.

9. A process for glow discharge deposition in an apparatus comprising, a first deposition chamber adapted to be evacuated, first gas introducing means for introducing a first gaseous material into said first deposition chamber, first electrode means disposed in said first deposition chamber, a second deposition chamber adapted to be evacuated, second gas introducing means for introducing a second gaseous material into said second deposition chamber, second electrode means disposed in said second deposition chamber, first restricting means for restricting the flow of at least one of said first and second gaseous materials from one of said first and second deposition chambers into the other one of said first and second deposition chambers, said first restricting means being disposed between said first deposition chamber and said second deposition chamber, a third deposition chamber adapted to be evacuated, third gas introducing means for introducing a third gaseous material into said third deposition chamber, third electrode means disposed in said third deposition chamber, second restricting means for restricting the flow of at least one of said second and third gaseous materials from one of said second and third deposition chambers into the other one of said second and third deposition chambers said second restricting means being disposed between said second deposition chamber and said third deposition chamber, and transporting means for transporting a substrate, said process comprising the steps of:

disposing said substrate in said first deposition chamber;

introducing said first gaseous material in said first deposition chamber and applying a first electric field to a first region in said first deposition chamber by said first electrode means so as to generate a first glow discharge, whereby a first layer is deposited on said substrate;

transporting said substrate on which said first layer is deposited from said first deposition chamber to said second deposition chamber through said first restricting means, while each interior of said deposition chambers is shielded from an external atmosphere;

disposing said substrate on which said first layer is deposited in said second deposition chamber;

introducing said second gaseous material in said second deposition chamber and applying a second electric field to a second region in said second deposition chamber by said second electrode so as to generate a second glow discharge, whereby a second layer is deposited on said first layer;

transporting said substrate on which said first layer and said second layer are deposited from said second deposition chamber to said third deposition chamber through said second restricting means, while each interior of said second and third deposition chambers is shielded from the external atmosphere;

disposing said substrate on which said first layer and said second layer are deposited in said third deposition chamber; and

introducing said third gaseous material in said third deposition chamber and applying a third electric field to a third region in said third deposition chamber by said third electrode means so as to generate a third glow discharge, whereby a third layer is deposited on said second layer.

28. The method of claim 9 in which said films comprising silicon and hydrogen also comprise nitrogen.

29. The method of claim 28 further comprising the step of fabricating an electrical contact to said film comprising silicon, hydrogen and nitrogen to form an insulated gate of a field effect transistor.

30. The method of claim 29 further comprising the step of positioning a metal oxide dielectric between said electrical contact and said film comprising silicon, hydrogen and nitrogen.

10. A method of making a semiconductor device on a substrate comprising the steps of:

providing a first and second vacuum chambers;

evacuating said first and second vacuum chambers;

disposing said substrate in said first vacuum chamber;

introducing a first gaseous material into said first vacuum chamber;

applying a first glow discharge to a region in said first vacuum chamber, said first glow discharge depositing a first film on said substrate while maintaining said first gaseous material at sub-atmospheric pressure and while isolating said first vacuum chamber;

transporting said substrate with said first film from said first vacuum chamber into said second vacuum chamber;

introducing a second gaseous material into said second vacuum chamber; and

,

applying a second glow discharge to a region in said second vacuum chamber, said second glow discharge depositing a second film on said substrate while maintaining said second gaseous material at sub-atmospheric pressure, and while isolating said second vacuum chamber wherein at least one of said first and second gaseous materials and at least one of said films comprises silicon and hydrogen.

11. The method of claim 10 in which one of said first and second gaseous materials in one of said vacuum chambers comprises nitrogen and the other of said first and second gaseous materials is substantially free of said nitrogen from said one of said vacuum chambers.

12. The method of claim 10 in which one of said first and second gaseous materials in one of said vacuum chambers comprises a dopant and the other of said gaseous materials is substantially free of said dopant from said one of said vacuum chambers.

13. The method of claim 10 which includes the steps of;

providing a third vacuum chamber;

disposing said substrate in said third vacuum chamber in gas at atmospheric pressure while restricting the flow of said gas at atmospheric pressure between said third vacuum chamber and said first and second vacuum chambers;

evacuating said third vacuum chamber; and

,

transporting said substrate from said third vacuum chamber to one of said first and second vacuum chambers while restricting the flow of gases between said first, second and third chambers.

14. The method of claim 13 in which a gas lock restricts the flow of gases between said vacuum chambers.

15. The method of claim 13 in which differential pumping is provided to restrict the flow of gases between said vacuum chambers.

16. The method of claim 14 further comprising:

opening said gas lock; and

transporting said substrate through said gas lock along a path through an evacuable zone between said vacuum chambers while said zone is being evacuated.

17. The method of claim 16 in which a movable arm transports said substrate through said gas lock between said vacuum chambers.

18. The method of claim 10 further comprising the steps of:

providing a third vacuum chamber;

evacuating said third vacuum chamber;

transporting said substrate from said second vacuum chamber to said third vacuum chamber while restricting the flow of gases between said first, second and third vacuum chambers; and

,

introducing a gas at atmospheric pressure into said third vacuum chamber while restricting the flow of said gas at atmospheric pressure between said third vacuum chamber and said first and second vacuum chambers.

19. A process for making a film on the surface of a substrate using a gaseous material at sub-atmospheric pressure suitable for sustaining a glow discharge in a vacuum chamber having first and second electrodes juxtaposed in face-to-face spaced relation with said second electrode having an internal cavity and a plurality of apertures formed there through, comprising the steps of:

positioning said electrodes in face-to-face spaced relation;

disposing said substrate on said first electrode;

introducing a gaseous material comprising silicon and hydrogen at sub-atmospheric pressure into said internal cavity and through said plurality of apertures in said second electrode; and

,

maintaining a glow discharge in said gaseous material between said electrodes to form said film on said substrate.

20. A method of making a semiconductor device on a semitransparent substrate having a layer of conducting metal oxide comprising indium comprising the steps of:

providing a vacuum chamber having a first electrode;

disposing said substrate on the surface of said first electrode in said vacuum chamber;

introducing a gaseous material comprising phosphorous at sub-atmospheric pressure into said vacuum chamber;

applying a first glow discharge to a region in said vacuum chamber to fabricate a first film comprising phosphorous on said layer of conducting metal oxide comprising indium on the surface of said substrate;

introducing a second gaseous material comprising silicon and hydrogen at sub-atmospheric pressure into said vacuum chamber; and

,

applying a second glow discharge to a region in said vacuum chamber to fabricate a second film comprising silicon and hydrogen on said first film so that a phosphorous-doped ohmic-contact is formed between said films.

21. A method of fabricating a semiconductor device comprising the steps of:

providing a first and second vacuum chambers;

providing an airlock in said first vacuum chamber;

disposing a substrate in said first vacuum chamber in a first gaseous material at atmospheric pressure while said airlock is closed;

evacuating said first and said second vacuum chambers;

transporting said substrate from said first vacuum chamber to said second vacuum chamber;

introducing a second gaseous material comprising silicon and hydrogen into said second vacuum chamber; and

,

applying a glow discharge to a region in said second vacuum chamber to said second gaseous material, said glow discharge depositing a film comprising silicon on said substrate while maintaining said second gaseous material at sub-atmospheric pressure, while maintaining said substrate at a temperature and while said airlock is closed.

22. The method of claim 21 in which said film comprising silicon also comprises nitrogen.

23. The method of claim 21 in which said film comprising silicon also comprises phosphorous.

24. The method of claim 21 further comprising the steps of:

projecting an electric field into said region of said second chamber; and

,

controlling said electric field and said pressure of said second gaseous material to position said glow discharge relative to said substrate.

25. The method of claim 21 further comprising the step of:

providing a movable armature for transporting said substrate from said first vacuum chamber through said airlock through a zone to said second vacuum chamber.

26. The method of claim 22 further comprising the step of fabricating an electrical contact to said film comprising silicon and nitrogen to form an insulated gate of a field effect transistor.

27. The method of claim 26 further comprising the step of positioning a metal oxide dielectric between said electrical contact and said film comprising silicon and nitrogen.

31. The method of producing a semiconductor device comprising the steps of:

providing a first and a second evacuable enclosures;

providing a first airlock in said first enclosure;

evacuating said first enclosure;

introducing a first gaseous material comprising silicon in said first enclosure;

generating a first glow discharge in said first gaseous material in said first enclosure, said first glow discharge depositing a first film comprising silicon on said substrate while maintaining first gaseous material at subatmospheric pressure and while said first airlock is closed;

providing a second airlock in said second enclosure;

evacuating said second enclosure;

transporting said substrate from said first enclosure through a zone outside of said first enclosure into said second enclosure;

positioning said substrate in said second enclosure;

evacuating said second enclosure;

introducing a second gaseous material in said second enclosure; and

,

generating a second glow discharge in said second enclosure, said second glow discharge depositing a second film on said first film comprising silicon while maintaining said second gaseous material at subatmospheric pressure and while said second airlock is closed.

32. The method of claim 31 in which said second gaseous material comprises a dopant gas and said first gaseous material comprising silicon is substantially free of said dopant gas.

33. The method of claim 31 in which said second gaseous material comprises nitrogen and said first gaseous material comprising silicon is substantially free of said nitrogen.

34. The method of claim 31 in which said semiconductor device comprises a field effect transistor (FET).