Erosion / corrosion resistant barrier coating
Disclosed are barrier coatings for fused silica components used in semiconductor processing. In particular, the present disclosure concerns protective substrate-barrier coatings composed of corrosion-resilient metal compounds which provide superior resistance to erosion/corrosion when a coated substrate is subjected to the acidic environments at elevated temperatures typical for semiconductor processing.
1. An improved fused silica surfaced apparatus for use in the high temperature acid environment of a chemical vapor deposition reaction chamber used for semiconductor processing, the improvement comprising an alumina-free coating comprising a tantalum compound barrier on the fused silica surface, the barrier sufficient to resist erosion of the fused silica at temperatures in excess of 1000° C. in the presence of hydrochloric acid.
2. The improved fused silica surfaced apparatus of claim 1 , wherein the apparatus is one of a thermocouple, a spider, chamber wall, or other fused silica apparatus used in chip fabrication.
3. The improved fused silica surfaced apparatus of claim 1 , wherein the barrier is sufficient to resist erosion at temperatures in excess of 1150° C. in the presence of hydrochloric acid.
4. The improved fused silica surfaced apparatus of claim 3 , wherein the barrier is sufficient to resist erosion at temperatures in excess of 1250° C. in the presence of hydrochloric acid.
5. The improved fused silica surfaced apparatus of claim 1 wherein the coating is applied by the process of applying a mixture of (i) at least one tantalum compound, (ii) at least one thixotropic matrix component; and (iii) an inert solvent, to the fused silica surface, and thermochemically reacting the mixture to form the barrier.
6. The improved fused silica surfaced apparatus of claim 5 wherein the mixture has a pH less than or equal to 2 at application.
7. The improved fused silica surfaced apparatus of claim 5 wherein the tantalum compound is selected from the group consisting of tantalum carbide compounds (TaC x ), TaB 2 , Ta 4 HfC 5 , TaN, tantalum pentafluoride (TaF 5 ), tantalum pentaiodide (Ta 2 I 10 ), tantalum pentoxide (Ta 2 O 5 ), tantalum telluride (TaTe 2 ), tantalum(III) aluminide (TaAl 3 ), tantalum(IV) sulfide (TaS 2 ), tantalum(V) bromide (Ta 2 Br 10 ), tantalum(V) ethoxide (Ta 2 (OC 2 H 5 ) 10 ), tantalum(V) chloride (TaCl 5 ), TaO 2 , TaCl 4 , and Ta 3 Al, and combinations thereof.
8. The improved fused silica surfaced apparatus of claim 7 , wherein the tantalum compound is tantalum(V) chloride (TaCl 5 ).
9. The improved fused silica surfaced apparatus of claim 7 , wherein the at least one thixotropic matrix component comprises a silicate compound.
10. The improved fused silica surfaced apparatus of claim 9 , wherein the silicate compound is fumed silica.
11. The improved fused silica surfaced apparatus of claim 9 , wherein the inert solvent is ultra-pure water.
12. The improved fused silica surfaced apparatus of claim 11 , wherein the ratio of components (i):(ii) is about 3:1 by weight.
13. The improved fused silica surfaced apparatus of claim 11 , wherein the ratio of components (i):(iii) is about 75:25 by weight percentage, and wherein component (i) is tantalum(V) chloride (TaCl 5 ) and component (ii) is fumed silica.
14. The improved fused silica surfaced apparatus of claim 13 , wherein the weight by solids in the inert solvent is about 13% w/v, and wherein the inert solvent is ultra-pure water.
15. The improved fused silica surfaced apparatus of claim 14 , wherein the barrier has a coefficient of thermal expansion similar to that of the fused silica surface to which it is applied.
16. The improved fused silica surfaced apparatus of claim 1 wherein the barrier comprises multiple layers.
17. The improved fused silica surfaced apparatus of claim 1 wherein the barrier has thickness of about 5 and about 20 μm.
18. A method of applying an aluminum-free coating comprising a protective barrier to a fused silica surfaced apparatus used in a chemical vapor deposition reaction chamber for semiconductor processing, the method comprising:
applying a mixture of (i) at least one tantalum compound, (ii) at least one thixotropic matrix component; and (iii) an inert solvent, to the fused silica surface, and thermochemically reacting the mixture to form the barrier sufficient to resist devitrification at temperatures in excess of 1000° C. in the presence of hydrochloric acid.
19. The method according to claim 18 wherein the mixture has a pH less than or equal to 3 at application.
20. The method according to claim 18 wherein the tantalum compound is selected from the group consisting of tantalum carbide compounds (TaC x ), TaB 2 , Ta 4 HfC 5 , TaN, tantalum pentafluoride (TaF 5 ), tantalum pentaiodide (Ta 2 I 10 ), tantalum pentoxide Ta 2 O 5 , tantalum telluride (TaTe 2 ), tantalum(III) aluminide (TaAl 3 ), tantalum(IV) sulfide (TaS 2 ), tantalum(V) bromide (Ta 2 Br 10 ), tantalum(V) ethoxide (Ta 2 (OC 2 H 5 ) 10 ), tantalum(V) chloride (TaCl 5 ), TaO 2 , TaCl 4 , and Ta 3 Al, and combinations thereof.
21. The method according to claim 20 , wherein the tantalum compound is tantalum(V) chloride (TaCl 5 ).
22. The method according to claim 21 , wherein the at least one thixotropic matrix component comprises a silicate compound.
23. The method according to claim 22 , wherein the silicate compound is fumed silica.
24. The method according to claim 23 , wherein the inert solvent is ultra-pure water.
25. The method according to claim 23 , wherein the ratio of components (i):(ii) is about 3:1 by weight.
26. The method according to claim 24 , wherein the ratio of components (i):(iii) is about 75:25 by weight percentage, and wherein component (i) is tantalum(V) chloride (TaCl 5 ) and component (ii) is fumed silica.
27. The method according to claim 25 , wherein the weight by solids in the inert solvent is about 13% w/v, and wherein the inert solvent is ultra-pure water.