Mesoporous silica films with mobile ion gettering and accelerated processing

• US 6,559,070 B1
• Filed: 04/11/2000
• Issued: 05/06/2003
• Est. Priority Date: 04/11/2000
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Mandal, Robert P.
• Primary Examiner(s): Chaudhuri, Olik
• Assistant Examiner(s): Maldonado, Julio J.
• Application Number:
  US09/547,714
• Time in Patent Office: 1,120 Days
• Field of Search: 438/638, 438/624, 438/790, 438/787, 438/781, 438/782, 438/794, 438/793, 438/778, 438/99, 438/780
• US Class Current: 438/781
• CPC Class Codes: C01B 37/02 Crystalline silica-polymorphs, e.g. silicalites dealuminated aluminosilicate zeolites
• CPC Class Codes: C23C 16/54 Apparatus specially adapted for continuous coating
• CPC Class Codes: H01L 21/02129 the material being boron or phosphorus doped silicon oxides, e.g. BPSG, BSG or PSG
• CPC Class Codes: H01L 21/02203 the layer being porous
• CPC Class Codes: H01L 21/02214 the compound comprising silicon and oxygen
• CPC Class Codes: H01L 21/02282 liquid deposition, e.g. spin-coating, sol-gel techniques, spray coating
• CPC Class Codes: H01L 21/02304 formation of intermediate layers, e.g. buffer layers, layers to improve adhesion, lattice match or diffusion barriers
• CPC Class Codes: H01L 21/02337 treatment by exposure to a gas or vapour
• CPC Class Codes: H01L 21/02359 treatment to change the surface groups of the insulating layer
• CPC Class Codes: H01L 21/02362 formation of intermediate layers, e.g. capping layers or diffusion barriers
• CPC Class Codes: H01L 21/31695 Deposition of porous oxides or porous glassy oxides or oxide based porous glass

Abstract

The present invention generally provides a process and an apparatus for depositing low dielectric constant films on a substrate. The low dielectric constant films are phosphorus doped mesoporous oxide films formed by depositing and curing a phosphorus containing sol-gel precursor to form an oxide film having interconnecting pores of uniform diameter, and then annealing the film in an inert gas atmosphere or exposing the film to an oxidizing atmosphere containing a reactive oxygen species to form a phosphorus doped mesoporous oxide film.

Claims

1. A process for forming a mesoporous oxide film on a substrate, comprising:

forming a sol-gel precursor comprising a silicon/oxygen compound, a phosphorus containing acid solution, an organic solvent, water, and a surfactant;

depositing the sol-gel precursor on the substrate;

curing the deposited sol-gel precursor to form an oxide film; and

exposing the oxide film to a surfactant removing process to form a mesoporous oxide film having a phosphorus oxide concentration between about 2% and about 8% by weight.

2. The process of claim 1, wherein the silicon/oxygen compound is selected from the group consisting of tetraethylorthosilicate, methyltriethoxysilane, phenyltriethoxysilane, hexaethoxydisiloxane, p-bis(triethoxysilyl)benzene, bis(triethoxysilyl)methane, and combinations thereof.

3. The process of claim 2, wherein the silicon/oxygen compound further comprises one or more phosphonic acid ligands, (—

PO(OH)₂).

4. The process of claim 3, wherein the silicon/oxygen compound is selected from the group of o-phosphotriethoxysilane (CH₃CH₂O)₃SiOPO(OH)₂, o-phosphoethylenetriethoxysilane (CH₃CH₂O)₃SiCH₂CH₂OPO(OH)₂, phosphorylethylenetriethoxysilane (CH₃CH₂O)₃SiCH₂CH₂PO(OH)₂, p-phosphorylphenylenetriethoxysilane (CH₃CH₂O)₃Si(C₆H₄)PO(OH)₂, phosphonotriethoxysilyl ketone (CH₃CH₂O)₃SiC(O)PO(OH)₂, phosphonotriethoxysilane CH₃CH₂O)₃SiPO(OH)₂, and combinations thereof.

5. The process of claim 1, wherein the organic solvent is selected from the group consisting of ethanol, isopropanol, n-propanol, n-butanol, sec-butanol, t-butanol, ethylene glycol, and combinations thereof.

6. The process of claim 1, wherein the phosphorus containing acid solution is a phosphorus based acid selected from the group consisting of orthophosphoric acid (H₃PO₄), ammonium dihydrogen phosphate, tetramethylammonium dihydrogen phosphate, phosphate esters of long-chain alcohols, alkoxysilylphosphonates, substituted derivatives thereof, and combinations thereof.

7. The process of claim 1, wherein the phosphorus containing acid solution further comprises a volatile inorganic acid selected from the group consisting of nitric acid, hydrochloric acid, perchloric acid, and combinations thereof.

8. The process of claim 1, wherein the phosphorus containing acid solution further comprises an organic acid selected from the group consisting of oxalic acid, glyoxylic acid, and combinations thereof.

9. The process of claim 1, wherein the surfactant is selected from the group consisting of p-(CH₃)₃C—

CH₂—

C₆H₄—

CH₂—

(OCH₂CH₂)₈OH, p-(CH₃)₃COC₆H₄CH₂(OCH₂CH₂)₈—

OH, polyethylene oxide co-polymer derivatives, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer derivatives, and combinations thereof.

10. The process of claim 1, wherein the surfactant further comprises a phosphorus component.

11. The process of claim 10, wherein the phosphorus based component is a phosphate of a alcohol-terminated surfactant selected from the group comprising p-(CH₃)₃CCH₂C₆H₄CH₂(OCH₂CH₂)_N—

OH, p-(CH₃)₃COC₆H₄CH₂(OCH₂CH₂)_N—

OH, CH₃(CH₂)_K—

OH, CH₃(CH₂)_I(CH₂CH₂O)_J—

OH, HO(CH₂CH₂O)_M(CH₂C(CH3)HO)_L(CH₂CH₂O)_MH, p-(CH₃)₃CCH₂C(CH₃)₂C₆H₄(OCH₂CH₂)_N—

OH, and fluorinated derivatives thereof, and combinations thereof, wherein N is an integer from 6 to 12, K is an integer from 13 to 17, I is an integer from 6 to 15, J is an integer from 20 to 106, and L is an integer from 20 to 80.

12. The process of claim 1, wherein the phosphorus containing acid comprises,

an phosphoric based acid selected from the group consisting of orthophosphoric acid (H₃PO₄), ammonium dihydrogen phosphate, tetramethylammonium dihydrogen phosphate, phosphate esters of long-chain alcohols, alkoxysilylphosphonates, substituted derivatives thereof, and combinations thereof; and

a volatile acid selected from the group consisting of nitric acid, hydrochloric acid, perchloric acid, and combinations thereof.

13. The process of claim 1, wherein the phosphorus containing acid solution has a pH of about 2.

14. The process of claim 1, wherein the phosphorus containing acid solution has a pH of about 6 to about 7 following the curing the deposited sol-gel precursor.

15. The process of claim 1, wherein the surfactant removing process comprises exposing the film to an oxidizing environment at a temperature between about 200°

C. to about 400°

C.

16. The process of claim 1, wherein the surfactant removing process comprises heating the film at a temperature of about 200°

C. to about 450°

C. in an inert atmosphere.

17. A process for forming a mesoporous oxide film on a substrate, comprising:

a. forming a first sol-gel precursor comprising a first silicon/oxygen compound, a organic acid, a first organic solvent, water, and a first surfactant;

b. forming a second sol-gel precursor comprising a second silicon/oxygen compound, a phosphorus based acid, a second organic solvent, water, and a second surfactant

c. mixing the first and second sol-gel precursors to form a mixed sol-gel precursor, wherein the first and second sol-gel precursors are mixed in a first to second ratio of between about 1;

1 and about 10;

1;

d. depositing the mixed sol-gel precursor on the substrate;

e. curing the deposited mixed sol-gel precursor to form an oxide film; and

f. exposing the oxide film to a surfactant removing process to form a mesoporous oxide film.

18. The process of claim 17, wherein the first and second silicon/oxygen compound are selected from the group consisting of tetraethylorthosilicate, methyltdethoxysilane, phenyltriethoxysilane, hexaethoxydisiloxane, p-bis(triethoxysilyl)benzene, bis(triethoxysilyl)methane, and combinations thereof.

19. The process of claim 18, wherein the first and second silicon/oxygen compound further comprise one or more phosphonic acid ligands, (—

PO(OH)₂).

20. The process of claim 19, wherein the first and second silicon/oxygen compound is selected from the group of o-phosphotriethoxysilane (CH₃CH₂O)₃SiOPO(OH)₂, o-phosphoethylenetriethoxysilane (CH₃CH₂O)₃SiCH₂CH₂OPO(OH)₂, phosphorylethylenetriethoxysilane (CH₃CH₂O)₃SiCH₂CH₂PO(OH)₂, p-phosphorylphenylenetriethoxysilane (CH₃CH₂O)₃Si(C₆H₄)PO(OH)₂, phosphonotriethoxysilyl ketone (CH₃CH₂O)₃SiC(O)PO(OH)₂, phosphonotriethoxysilane (CH₃CH₂O)₃SiPO(OH)₂, and combinations thereof.

21. The process of claim 17, wherein the first and second organic solvents are selected from the group consisting of ethanol, isopropanol, n-propanol, n-butanol, sec-butanol, t-butanol, ethylene glycol, and combinations thereof.

22. The process of claim 17, wherein the phosphorus containing acid solution is a phosphorus based acid selected from the group consisting of orthophosphoric acid (H₃PO₄), ammonium dihydrogen phosphate, tetramethylammonium dihydrogen phosphate, phosphate esters of long-chain alcohols, alkoxysilylphosphonates, substituted derivatives thereof, and combinations thereof.

23. The process of claim 17, wherein the phosphorus containing acid solution further comprises a volatile inorganic acid selected from the group consisting of nitric acid, hydrochloric acid, perchloric acid, and combinations thereof.

24. The process of claim 17, wherein the phosphorus containing acid solution further comprises an organic acid selected from the group consisting of oxalic acid, glyoxylic acid, and combinations thereof.

25. The process of claim 17, wherein the first and second surfactants are selected from the group consisting of p-(CH₃)₃C—

CH₂—

C₆H₄—

CH₂—

(OCH₂CH₂)₈OH, p-(CH₃)₃COC₆H₄CH₂(OCH₂CH₂)₈—

OH, and other polyethylene oxide co-polymer derivatives, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer derivatives, and combinations thereof.

26. The process of claim 17, wherein the first and second surfactants further comprise a phophorus component.

27. The process of claim 26, wherein the phosphorus based component is a phosphate of a alcohol-terminated surfactant selected from the group comprising p-(CH₃)₃CCH₂C₆H₄CH₂(OCH₂CH₂)_N—

OH, p-(CH₃)₃COC₆H₄CH₂(OCH₂CH₂)_N—

OH, CH₃(CH₂)_K—

OH, CH₃(CH₂)_I(CH₂CH₂O)_J—

OH, HO(CH₂CH₂O)_M(CH₂C(CH3)HO)_L(CH₂CH₂O)_MH, p-(CH₃)₃CCH₂C(CH₃)₂C₆H₄(OCH₂CH₂)_N—

OH, and fluorinated derivatives thereof, and combinations thereof, wherein N is an integer from 6 to 12, K is an integer from 13 to 17, I is an integer from 6 to 15, J is an integer from 20 to 106, and L is an integer from 20 to 80.

28. The process of claim 17, wherein the phosphorus containing acid comprises:

a phosphoric based acid selected from the group consisting of orthophosphoric acid (H₃PO₄), ammonium dihydrogen phosphate, tetramethylammonium dihydrogen phosphate, phosphate esters of long-chain alcohols, alkoxysilylphosphonates, substituted derivatives thereof, and combinations thereof; and

a volatile acid selected from the group consisting of nitric acid, hydrochloric acid, perchloric acid, and combinations thereof.

29. The process of claim 17, wherein the phosphorus containing acid solution has a pH of about 2.

30. The process of claim 17, wherein the phosphorus containing acid solution has a pH of about 6 to about 7 following the curing the deposited sol-gel precursor.

31. The process of claim 17, wherein the mesoporous oxide film has a phosphorus oxide concentration of between about 2% and about 8% by weight.

32. The process of claim 17, wherein the surfactant removing process comprises exposing the film to an oxidizing environment at a temperature between about 200°

C. to about 400°

C.

33. The process of claim 17, wherein the surfactant removing process comprises heating the film at a temperature of about 200°

C. to about 450°

C. in an inert atmosphere.

37. The method of claim 26, further comprising depositing a capping layer on the copper layer.

38. The method of claim 26, wherein the first and second phosphorus doped mesoporous oxide films have a phosphorus oxide concentration of between about 2% and about 8% by weight.

34. A method of forming a dual damascene structure, comprising:

depositing a first etch stop on a substrate;

depositing a first phosphorus doped mesoporous oxide film having a phosphorus oxide concentration between about 2% and about 8% by weight on the first etch stop by;

forming a sol-gel precursor comprising a silicon/oxygen compound, a phosphorus containing acid solution, an organic solvent, water, and a surfactant;

depositing the sol-gel precursor on the substrate;

curing the deposited sol-gel precursor to form an oxide film; and

exposing the oxide film to a surfactant removing process to form the first phosphorus doped mesoporous oxide film;

depositing a second etch stop on the first phosphorus doped mesoporous oxide film;

depositing a second phosphorus doped mesoporous oxide film on the second etch stop by;

forming a sol-gel precursor comprising a silicon/oxygen compound, a phosphorus containing acid solution, an organic solvent, water, and a surfactant;

depositing the sol-gel precursor on the substrate;

curing the deposited sol-gel precursor to form an oxide film; and

exposing the oxide film to a surfactant removing process to form the second phosphorus doped mesoporous oxide film;

depositing a third etch stop on the second phosphorus doped mesoporous oxide film;

etching the third etch stop and second phosphorus doped mesoporous oxide film to define a vertical interconnect opening; and

etching the second etch stop, the first phosphorus doped mesoporous oxide film, and the first etch stop through the vertical interconnect opening to further define the vertical interconnect, thereby exposing the substrate, and etching the third etch stop and the second phosphorus doped mesoporous oxide film to define a horizontal interconnect and form a dual damascene feature.

35. The method of claim 34, further comprising depositing a conformal barrier layer film in the defined interconnect.

36. The method of claim 35, further comprising depositing a copper layer on the conformal barrier layer.

39. The method of claim 36, wherein the horizontal interconnect opening is defined by depositing a patterned oxide layer on the third etch stop prior to etching the third etch stop and the second phosphorus doped mesoporous oxide films.

40. The method of claim 36, wherein the vertical interconnect opening is defined by depositing a patterned photoresist film on the patterned oxide layer prior to etching the third etch stop and second phosphorus doped mesoporous oxide films.