Method for forming strained silicon nitride films and a device containing such films

• US 20080242116A1
• Filed: 03/30/2007
• Published: 10/02/2008
• Est. Priority Date: 03/30/2007
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Clark, Robert D.
• Granted Patent: US 7,651,961 B2
• Time in Patent Office: Days
• US Class Current: 438/791
• CPC Class Codes: C23C 16/345 Silicon nitride
• CPC Class Codes: C23C 16/45542 Plasma being used non-continuously during the ALD reactions
• CPC Class Codes: C23C 16/515 using pulsed discharges
• CPC Class Codes: H01L 21/0217 the material being a silicon nitride not containing oxygen, e.g. SixNy or SixByNz H01L21/02126 and H01L21/0214 take precedence
• CPC Class Codes: H01L 21/02211 the compound being a silane, e.g. disilane, methylsilane or chlorosilane
• CPC Class Codes: H01L 21/02274 in the presence of a plasma [PECVD]
• CPC Class Codes: H01L 21/0228 deposition by cyclic CVD, e.g. ALD, ALE, pulsed CVD
• CPC Class Codes: H01L 21/3185 of siliconnitrides
• CPC Class Codes: H01L 29/78 with field effect produced by an insulated gate H01L29/7725, H01L29/775, H01L29/778 take precedence
• CPC Class Codes: H01L 29/7843 the means being an applied insulating layer

Abstract

A method for forming a strained SiN film and a semiconductor device containing the strained SiN film. The method includes exposing the substrate to a gas including a silicon precursor, exposing the substrate to a gas containing a nitrogen precursor activated by a plasma source at a first level of plasma power and configured to react with the silicon precursor with a first reactivity characteristic, and exposing the substrate to a gas containing the nitrogen precursor activated by the plasma source at a second level of plasma power different from the first level and configured to react with the silicon precursor with a second reactivity characteristic such that a property of the silicon nitride film formed on the substrate changes to provide the strained silicon nitride film.

Claims

1. A method of depositing a strained SiN film on a substrate in a process chamber, comprising:

exposing the substrate to a gas comprising a silicon precursor;

exposing the substrate to a gas comprising a nitrogen precursor activated by a plasma source at a first level of plasma power and configured to react with the silicon precursor with a first reactivity characteristic; and

exposing the substrate to a gas comprising the nitrogen precursor activated by the plasma source at a second level of plasma power different from the first level and configured to react with the silicon precursor with a second reactivity characteristic such that a property of the SiN film formed on the substrate changes to provide the strained SiN film.

2. The method of claim 1, comprising:

a) exposing the substrate to a gas pulse comprising the silicon precursor;

b) exposing the substrate to a gas pulse comprising the nitrogen precursor activated by the plasma source at the first level of plasma power;

c) exposing the substrate to a gas pulse comprising the silicon precursor;

d) exposing the substrate to a gas pulse comprising the nitrogen precursor activated by the plasma source at the second level of plasma power; and

e) repeating steps a)-d) a predetermined number of times.

3. The method of claim 2, further comprising sequentially performing steps a) and b) a first number of times prior to performing steps c) and d).

4. The method of claim 2, further comprising sequentially performing steps c) and d) a second number of times prior to repeating steps a) and b) in step e).

5. The method of claim 2, further comprising sequentially performing steps a) and b) a first number of times prior to performing steps c) and d), and sequentially performing steps c) and d) a second number of times prior to repeating steps a) and b) in step e).

6. The method of claim 5, wherein step e) further comprises varying the first number of times or the second number of times, or both the first and second number of times during deposition of the strained SiN film

7. The method of claim 2, wherein the first level of plasma power or the second level of plasma power, or both first and second levels of plasma power are varied during deposition of the strained SiN film.

8. The method of claim 7, wherein the first level of plasma power or the second level of plasma power, or both first and second levels of plasma power are between a lower level of plasma power at or below a lower limit for plasma formation and an upper level of plasma power corresponding to a maximum desired level of plasma power.

9. The method of claim 1, wherein the silicon precursor comprises silane, disilane, monochlorosilane, dichlorosilane, trichlorosilane, hexachlorodisilane, diethylsilane, or an alkylaminosilane, or a combination of two or more thereof.

10. The method of claim 9, wherein the alkylaminosilane comprises di-isopropylaminosilane (H₃Si(NiPr₂)), bis(diethylamino)silane (H₂Si(NEt₂)₂, bis(diisopropylamino)silane (H₂Si(NiPr₂)₂, tris(isopropylamino)silane (HSi(NiPr₂)₃), bis(tert-butylamino)silane ((tBu(H)N)₂SiH₂), tetrakis(dimethylamino)silane (Si(NMe₂)₄), tetrakis(ethylmethylamino)silane (Si(NEtMe)₄), tetrakis(diethylamino)silane (Si(NEt₂)₄), tris(dimethylamino)silane (HSi(NMe₂)₃), tris(ethylmethylamino)silane (HSi(NEtMe)₃), tris(diethylamino)silane (HSi(NEt₂)₃), or tris(dimethylhydrazino)silane (HSi(N(H)NMe₂)₃), or a combination of two or more thereof.

11. The method of claim 1, wherein the nitrogen precursor is selected from N₂, NH₃, N₂H₄, and C₁-C₁₀ alkyl hydrazine compounds.

12. The method of claim 2, further comprising purging or evacuating, or both purging and evacuating the process chamber after each of steps a)-d).

13. The method of claim 2, wherein steps a) and b) have at least partial temporal overlap.

14. The method of claim 2, wherein steps c) and d) have at least partial temporal overlap.

15. The method of claim 2, wherein steps a) and b) have at least partial temporal overlap and steps c) and d) have at least partial temporal overlap.

16. The method of claim 1, wherein the exposing the substrate to a gas comprising a nitrogen precursor activated by a plasma source at a first level of plasma power further comprises providing a dilution gas in a first dilution ratio with the nitrogen precursor, and wherein the exposing the substrate to a gas comprising the nitrogen precursor activated by the plasma source at a second level of plasma power further comprises providing the dilution gas in a second dilution ratio with the nitrogen precursor different from the first dilution ratio.

17. The method of claim 16, wherein the dilution gas is selected from He, Ar, Ne, Kr, Xe, or H₂, or a combination of two or more thereof.

26. A semiconductor device comprising a strained SiN film deposited according to claim 1.

18. A method of depositing a strained SiN film on a substrate in a process chamber, comprising:

exposing the substrate to a gas pulse comprising a silicon precursor and a nitrogen precursor activated at a level of plasma power, wherein the level of plasma power is varied during the exposure.

19. The method of claim 18, wherein the level of plasma power is varied between a first level at or below a lower limit for plasma formation and a second level of plasma power corresponding to a maximum desired level of plasma power.

20. The method of claim 18, wherein the level of plasma power is varied monotonically during the deposition of the SiN film.

21. The method of claim 18, wherein the nitrogen precursor is selected from N₂, NH₃, N₂H₄, and C₁-C₁₀ alkyl hydrazine compounds.

22. The method of claim 18, wherein the silicon precursor comprises silane, disilane, monochlorosilane, dichlorosilane, trichlorosilane, hexachlorodisilane, diethylsilane, or an alkylaminosilane, or a combination of two or more thereof.

23. The method of claim 22, wherein the alkylaminosilane comprises di-isopropylaminosilane (H₃Si(NiPr₂)), bis(diethylamino)silane (H₂Si(NEt₂)₂, bis(diisopropylamino)silane (H₂Si(NiPr₂)₂, tris(isopropylamino)silane (HSi(NiPr₂)₃), bis(tert-butylamino)silane ((tBu(H)N)₂SiH₂), tetrakis(dimethylamino)silane (Si(NMe₂)₄), tetrakis(ethylmethylamino)silane (Si(NEtMe)₄), tetrakis(diethylamino)silane (Si(NEt₂)₄), tris(dimethylamino)silane (HSi(NMe₂)₃), tris(ethylmethylamino)silane (HSi(NEtMe)₃), tris(diethylamino)silane (HSi(NEt₂)₃), or tris(dimethylhydrazino)silane (HSi(N(H)NMe₂)₃), or a combination of two or more thereof.

24. The method of claim 18, wherein the gas pulse further comprises dilution gas selected from He, Ar, Ne, Kr, Xe, or H₂, or a combination of two or more thereof.

25. The method of claim 21, wherein a ratio of the dilution gas and the nitrogen precursor is varied during the exposure.

27. A semiconductor device comprising a strained SiN film deposited according to claim 18.