Process for producing semi-conductor coated substrate
A process of producing a clean substrate for use in semi-conductor processing in which the substrate is roughened to produce microfissures therein and then treated with a high concentration of a strong acid followed by coating with a material containing at least one metal oxide.
1 . A process for producing a substrate suitable for use in semi-conductor processing, said process comprising:
a) roughening the surface of the substrate material to produce microfissures therein;
b) treating the roughened surface to remove at least substantially all particles of the substrate material remaining on the roughened surface; and
c) coating the roughened surface with a coating composition containing at least one metal oxide.
2 . The process of claim 1 wherein the substrate is comprised of a material selected from the group consisting of quartz, ceramics, metals and metal oxides.
3 . The process of claim 1 wherein the coating composition is selected from silicon dioxide, aluminum oxide, zirconium oxide, yttrium oxide and combinations thereof.
4 . The process of claim 3 wherein the coating composition comprises zirconium oxide and yttrium oxide.
5 . The process of claim 1 wherein the step of coating the roughened surface comprises generating a plasma comprising a plasma generating gas and the coating composition and directing the plasma toward said roughened surface in a manner sufficient to apply the coating composition to the roughened surface.
6 . The process of claim 5 further comprising generating the plasma in the presence of compressed air.
7 . The process of claim 5 comprising generating the plasma at a temperature of from about 10,000 to 30,000° F.
8 . The process of claim 5 wherein the plasma generating gas is selected from the group consisting of hydrogen, nitrogen, argon, helium and mixtures thereof.
9 . The process of claim 1 wherein the step of roughening the surface of the substrate material comprises:
a) contacting the substrate material with solid particles of a roughening material to produce a surface roughness in the range of from about 180 to 320 micro inch Ra.
10 . The process of claim 9 wherein the surface roughness is 200-300 micro inch Ra.
11 . The process of claim 1 wherein the step of treating the roughened surface comprises immersing the substrate in a high concentration, strong acid containing immersion bath.
12 . The process of claim 11 wherein the concentration of the strong acid is from 15 to 50 volume percent.
13 . The process of claim 11 wherein the concentration of the strong acid is from 25 to 35 volume percent.
14 . The process of claim 11 wherein the immersion bath comprises nitric acid and hydrofluoric acid.
15 . The process of claim 11 further comprising removing the substrate from the immersion bath and cleaning the substrate.
16 . The process of claim 1 wherein the depth of the microfissures is up to about 0.005 inch.
17 . The process of claim 1 wherein the depth of the microfissures is up to about 0.006 inch.
18 . The process of claim 1 wherein the thickness of the coating is sufficient to fill and cover the microfissures.
19 . The process of claim 18 wherein the thickness of the coating is up to about 0.010 inch.
20 . The process of claim 1 wherein the step of coating the roughened surface comprises applying the coating composition in the form of a plasma containing a plasma gas.
21 . The process of claim 20 comprising applying the coating composition in the form of a plasma at a temperature of from 10,000° F. to 30,000° F.
22 . The process of claim 1 wherein the coating is a dielectric coating.