Vapor phase repair and pore sealing of low-K dielectric materials

• US 7,998,875 B2
• Filed: 12/08/2008
• Issued: 08/16/2011
• Est. Priority Date: 12/19/2007
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: DeYoung, James
• Primary Examiner(s): LEE, HSIEN MING
• Application Number:
  US12/746,807
• Publication Number:
  US 20110020955A1
• Time in Patent Office: 981 Days
• Field of Search: 438/637, 438/638, 438/700, 438/725, 438/780, 438/781, 427/140, 427/337, 427/532, 257/642, 257/643, 257/E21.211, 257/E21.212, 257/E21.214, 257/E21.241
• US Class Current: 438/725
• CPC Class Codes: H01L 21/02126 the material containing Si, O, and at least one of H, N, C, F, or other non-metal elements, e.g. SiOC, SiOC:H or SiONC
• CPC Class Codes: H01L 21/02203 the layer being porous
• CPC Class Codes: H01L 21/02337 treatment by exposure to a gas or vapour
• CPC Class Codes: H01L 21/02343 treatment by exposure to a liquid
• CPC Class Codes: H01L 21/3105 After-treatment
• CPC Class Codes: H01L 21/31695 Deposition of porous oxides or porous glassy oxides or oxide based porous glass
• CPC Class Codes: H01L 21/76814 post-treatment or after-treatment, e.g. cleaning or removal of oxides on underlying conductors
• CPC Class Codes: H01L 21/76826 by contacting the layer with gases, liquids or plasmas
• CPC Class Codes: H01L 21/76831 in via holes or trenches, e.g. non-conductive sidewall liners

Abstract

A method of treating a nanoporous low-k dielectric material formed on a semiconductor substrate is provided. The low-k dielectric material has etched openings with an etch damaged region containing silanol groups on exterior surfaces of the etched openings and on interior surfaces of interconnected pores. First, the low-k dielectric material is contacted with a vapor phase catalyst in an amount effective to form hydrogen bonds between the catalyst and the silanol groups in the etch damaged region, forming a catalytic intermediary. Second, the low-k dielectric material is contacted with a vapor phase alkoxysilane repair agent in an amount effective to react with about 50% or more of the silanol groups in the etch damaged region, such that the alkoxysilane repair agent reacts with the catalytic intermediary; and/or the low-k dielectric material is contacted with a vapor phase alkoxysilane sealing agent in an amount effective to prevent diffusion of an overlying barrier layer into the interconnected pores, such that the alkoxysilane sealing agent reacts with the catalytic intermediary.

Claims

1. A method of treating a nanoporous low-k dielectric material formed on a semiconductor substrate, the low-k dielectric material having etched openings with an etch damaged region containing silanol groups on exterior surfaces of the etched openings and on interior surfaces of interconnected pores, comprising:

(a) contacting the low-k dielectric material with a vapor phase catalyst in an amount effective to form hydrogen bonds between the catalyst and the silanol groups in the etch damaged region, forming a catalytic intermediary, followed by;

at least one of

(b) contacting the low-k dielectric material with a vapor phase alkoxysilane repair agent in an amount effective to react with about 50% or more of the silanol groups in the etch damaged region, such that the alkoxysilane repair agent reacts with the catalytic intermediary; and

(c) contacting the low-k dielectric material with a vapor phase alkoxysilane sealing agent in an amount effective to prevent diffusion of an overlying barrier layer into the interconnected pores, such that the alkoxysilane sealing agent reacts with the catalytic intermediary.

2. The method of claim 1, wherein:

(i) the catalyst is a Lewis base amine or an organic acid;

(ii) step (a) and step (b) are repeated up to ten times prior to step (c);

(iii) the sealing agent forms an alkoxysilane film up to 2 nm in thickness on the exterior surfaces of the etched openings; and

/or the alkoxysilane repair agent has an atom mass unit of about 80 to about 125 and the alkoxysilane sealing agent has an atomic mass unit of about 200 to about 400.

3. The method of claim 2, wherein the Lewis base amine is ammonia (NH₃), methyl amine (CH₃NH₂), dimethyl amine (CH₃)₂NH) or trimethyl amine (N(CH₃)₃);

or the organic acid is an aqueous solution of acetic acid, trifluoroacetic acid, trichloroacetic acid or citric acid.

4. The method of claim 2, further comprising after step (a) and before step (b) removing the organic acid vapor phase catalyst from the low-k dielectric material to prevent vapor phase reactions between:

(i) the organic acid vapor phase catalyst and (ii) least one of the alkoxysilane repair agent and/or and the alkoxysilane sealing agent.

5. The method of claim 4, wherein the alkoxysilane repair agent is methyl trimethoxysilane (CH₃—

Si—

(O—

CH₃)₃), dimethoxy dimethylsilane ((CH₃)₂—

Si—

(OCH₃)₂), methoxy trimethylsilane ((CH₃)₃—

Si—

OCH₃) or n-propyl trimethoxysilane (CH₃—

CH₂—

CH₂—

Si—

(OCH₃)₃); and

the alkoxysilane sealing agent is bis(dimethoxymethyl)siloxane, bis(methyldimethyloxysilylpropyl)-N-methylamine, bis(triethoxysilyl)ethane, 1,2-bis(trimethoxysilyl)hexane, bis(trimethoxysilylpropyl)amine or bis(3-(triethoxysilyl)propyl)disulfide.

6. The method of claim 1, further comprising repeating step (a) prior to step (c).

7. The method of claim 1, wherein (a) contacting the low-k dielectric material with the vapor phase catalyst comprises:

placing the semiconductor substrate in a processing chamber and evacuating the processing chamber;

heating the semiconductor substrate to a first temperature of about 60°

C. to about 275°

C.;

introducing the catalyst into the chamber at a pressure of about 20 Torr to about 1500 Torr for a time of about 10 seconds to about 60 seconds; and

evacuating the chamber.

8. The method of claim 7, wherein the first temperature is about 100°

C. to about 200°

C., the pressure is about 100 Torr to about 760 Torr and the time is about 20 seconds to about 30 seconds.

9. The method of claim 7, wherein (b) contacting the low-k dielectric material with the vapor phase alkoxysilane repair agent or (c) contacting the low-k dielectric material with the vapor phase alkoxysilane sealing agent comprises:

heating the semiconductor substrate to a first temperature of about 60°

C. to about 275°

C.;

introducing the vapor phase alkoxysilane repair agent or the vapor phase alkoxysilane sealing agent into the chamber at a pressure of about 20 Torr to about 1500 Torr for a time of about 10 seconds to about 180 seconds; and

evacuating the chamber.

10. The method of claim 9, wherein the first temperature is about 100°

C. to about 200°

C., the pressure is about 100 Torr to about 760 Torr and the time is about 20 seconds to about 60 seconds.

11. The method of claim 9, wherein (b) contacting the low-k dielectric material with the vapor phase alkoxysilane repair agent or (c) contacting the low-k dielectric material with the vapor phase alkoxysilane sealing agent further comprises:

heating the semiconductor substrate to a second temperature of about 80°

C. to about 300°

C. for an additional time of about 10 seconds to about 180 seconds before evacuating the chamber; and

maintaining the semiconductor substrate at the second temperature for about 10 seconds to about 180 seconds after evacuating the chamber.

12. The method of claim 11, wherein the second temperature is about 150°

C. to about 250°

C. and the additional time is about 20 seconds to about 60 seconds.

13. The method of claim 7, further comprising:

(d) contacting the low-k dielectric material with an organic acid vapor phase catalyst in an amount effective to horizontally network the vapor phase alkoxysilane repair agent or vapor phase alkoxysilane sealing agent; and

(e) heating the low-k dielectric material to a temperature effective to horizontally network the vapor phase alkoxysilane repair agent or the vapor phase alkoxysilane sealing agent.

14. The method of claim 13, wherein (d) contacting the low-k dielectric material with an organic acid vapor phase catalyst in an amount effective to horizontally network the vapor phase alkoxysilane repair agent or the vapor phase alkoxysilane sealing agent comprises:

heating the semiconductor substrate to a first temperature of about 60°

C. to about 275°

C.;

introducing the organic acid vapor phase catalyst into the chamber at a pressure of about 20 Torr to about 1500 Torr for a time of about 10 seconds to about 60 seconds; and

evacuating the chamber.

15. The method of claim 13, wherein (e) heating the low-k dielectric material to a temperature effective to horizontally network the vapor phase alkoxysilane repair agent or the vapor phase alkoxysilane sealing agent comprises:

heating the semiconductor substrate to a temperature of about 200°

C. to about 300°

C. for about 60 seconds to about 180 seconds in the chamber;

or removing the semiconductor substrate from the chamber and placing the semiconductor substrate on a hotplate and heating the semiconductor substrate to a temperature of about 200°

C. to about 300°

C. for about 60 seconds to about 180 seconds.

16. A method of treating a nanoporous low-k dielectric material formed on a semiconductor substrate, the low-k dielectric material having etched openings with an etch damaged region containing silanol groups on exterior surfaces of the etched openings and on interior surfaces of interconnected pores, comprising:

(a) contacting the low-k dielectric material with a vapor phase organic acid catalyst in an amount effective to form hydrogen bonds between the catalyst and the silanol groups in the etch damaged region, forming a catalytic intermediary, followed by;

at least one of

(b) contacting the low-k dielectric material with a vapor phase alkoxysilane repair agent in an amount effective to react with about 50% or more of the silanol groups in the etch damaged region, such that the alkoxysilane repair agent reacts with the catalytic intermediary; and

(c) contacting the low-k dielectric material with a vapor phase alkoxysilane sealing agent in an amount effective to prevent diffusion of an overlying barrier layer into the interconnected pores, such that the alkoxysilane sealing agent reacts with the catalytic intermediary.

17. The method of claim 16, wherein the organic acid catalyst is an aqueous solution of acetic acid, trifluoroacetic acid, trichloroacetic acid or citric acid.

18. The method of claim 16, wherein the vapor phase alkoxysilane repair agent is methyl trimethoxysilane (CH₃—

Si—

(O—

CH₃)₃), dimethoxy dimethylsilane ((CH₃)₂—

Si—

(OCH₃)₂), methoxy trimethylsilane ((CH₃)₃—

Si—

OCH₃) or n-propyl trimethoxysilane (CH₃—

CH₂—

CH₂—

Si—

(OCH₃)₃); and

the vapor phase alkoxysilane sealing agent is bis(dimethoxymethyl)siloxane, bis(methyldimethyloxysilylpropyl)-N-methylamine, bis(triethoxysilyl)ethane, 1,2-bis(trimethoxysilyl)hexane, bis(trimethoxysilylpropyl)amine or bis(3-(triethoxysilyl)propyl)disulfide.

19. The method of claim 16, wherein (a) contacting the low-k dielectric material with a vapor phase organic acid catalyst comprises:

placing the semiconductor substrate in a processing chamber and evacuating the processing chamber;

heating the semiconductor substrate to a first temperature of about 60°

C. to about 275°

C.;

introducing the vapor phase organic acid catalyst into the chamber at a pressure of about 20 Torr to about 1500 Torr for a time of about 10 seconds to about 60 seconds; and

evacuating the chamber.

20. The method of claim 16, further comprising:

(d) contacting the low-k dielectric material with the vapor phase organic acid catalyst in an amount effective to horizontally network the vapor phase alkoxysilane repair agent or the vapor phase alkoxysilane sealing agent; and

(e) heating the low-k dielectric material to a temperature effective to horizontally network the vapor phase alkoxysilane repair agent or the vapor phase alkoxysilane sealing agent.