Multi-step polysilicon deposition process for boron penetration inhibition

• US 6,043,138 A
• Filed: 10/23/1997
• Issued: 03/28/2000
• Est. Priority Date: 09/16/1996
• Status: Expired due to Term

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: Advanced Micro Devices, Inc.
• Inventors: Ibok, Effiong E.
• Primary Examiner(s): Bowers, Charles
• Assistant Examiner(s): CHRISTIANSON, KEITH ALAN
• Application Number:
  US08/959,105
• Time in Patent Office: 887 Days
• Field of Search: 437/40 GS, 437/41 GS, 437/46, 437/239, 437/242, 437/954, 148/DIG. 35, 148/DIG. 112, 257/288, 257/364, 257/411, 257/407, 438/287, 438/491, 438/493, 438/591, 438/592, 438/763, 438/769, 438/775
• US Class Current: 438/493
• CPC Class Codes: H01L 21/28035 the final conductor layer next to the insulator being silicon, e.g. polysilicon, with or without impurities H01L21/28105 takes precedence
• CPC Class Codes: H01L 29/4925 with a multiple layer structure, e.g. several silicon layers with different crystal structure or grain arrangement with only a vertical doping structure or vertical doping variation H01L29/4916

Abstract

The present invention provides an improved semiconductor device and method of impeding the diffusion of boron by providing at least one layer of polysilicon and an interface substance. A semiconductor device according to the present invention is comprised of a substrate; gate oxide coupled to the substrate; a layer of polysilicon coupled to the gate oxide; and an interface layer between the layer of polysilicon and the gate oxide, wherein the interface layer impedes diffusion of doping material.

Claims

1. A semiconductor device comprising:

a substrate;

a first layer of polysilicon over the substrate, wherein the first layer has a thickness of approximately 20 to 500 angstroms;

an interface layer over the first layer of polysilicon, wherein the interface layer impedes diffusion of doping material, wherein the interface layer is formed by exposing the first layer of polysilicon to an oxidation ambient; and

a second layer of polysilicon over the interface layer, wherein the second layer of polysilicon is deposited separately in time from the first layer of polysilicon.

2. The semiconductor device of claim 1 wherein the first layer of polysilicon has a thickness of approximately 50 to 500 angstroms.

3. The semiconductor device of claim 1, wherein the first layer of polysilicon has a thickness which is not greater than 300 angstroms.

4. The semiconductor device of claim 1, wherein the first layer of polysilicon has a thickness of approximately 20 angstroms.

5. The semiconductor device of claim 4, wherein the second layer of polysilicon has a thickness of approximately 2,000 angstroms.

6. The semiconductor device of claim 1, wherein the interface layer includes oxygen and nitrogen.

7. The semiconductor device of claim 1 wherein the interface layer includes nitrogen.

8. The semiconductor device of claim 1, wherein the interface layer includes both nitrogen and oxygen from a combination of N₂ O and NH₃ sources.

9. A method for manufacturing semiconductors comprising the steps of:

a) providing a substrate;

b) providing a first layer of polysilicon over the substrate, wherein the first layer of polysilicon has a thickness of approximately 20 to 500 angstroms;

c) providing an interface layer over the first layer of polysilicon by exposing the first layer of polysilicon to an oxidation ambient; and

d) providing a second layer of polysilicon over the interface layer, wherein the second layer of polysilicon is deposited separately in time from the first layer of polysilicon.

10. The method of claim 9, wherein step (c) includes substep of exposing the first layer of polysilicon to an oxidation ambient, the exposure providing an oxide layer over the first layer of polysilicon.

11. The method of claim 9, wherein the first layer of polysilicon has a thickness approximately within the range of 50 to 500 angstroms.

12. The method of claim 9, wherein the first layer of polysilicon has a thickness which is not greater than 300 angstroms.

13. The method of claim 9, wherein the first layer of polysilicon has a thickness of approximately 20 angstroms.

14. The method of claim 13, wherein the second layer of polysilicon has a thickness of approximately 2,000 angstroms.

15. The method of claim 9, wherein the interface layer includes nitrogen and oxygen.

16. The method of claim 9, wherein the interface layer includes nitrogen.

17. The method of claim 9, wherein the interface layer includes both nitrogen and oxygen from a combination of N₂ 0 and NH₃ sources.

18. The method of claim 9, further comprising step (e) of implanting a doping substance onto the second layer of polysilicon, wherein the interface layer impedes diffusion of the doping substance.

19. A method of manufacturing semiconductors comprising:

a) providing a substrate;

b) depositing a first layer of polysilicon through a deposition stream over the substrate, wherein the first layer polysilicon has a thickness of approximately 20 to 500 angstroms;

c) forming an interface material by introducing an oxidation ambient into the deposition stream over the first layer of polysilicon; and

d) providing a second layer of polysilicon over the first layer of polysilicon and interface material, wherein the second layer of polysilicon is deposited separately in time from the first layer of polysilicon.

20. The method of claim 19, wherein the interface reactant gas includes N₂ O.

21. The method of claim 19, wherein the interface reactant gas includes NH₃.

22. The method of claim 19, further comprising step (e) of implanting a doping substance onto the second layer of polysilicon, wherein the interface layer impedes diffusion of the doping substance.

23. The method of claim 19, wherein the interface material includes oxygen and nitrogen.