Composition and method for polishing polysilicon
View Patent ↗The invention provides a polishing composition comprising silica, an aminophosphonic acid, a polysaccharide, a tetraalkylammonium salt, a bicarbonate salt, an azole ring, and water, wherein the polishing composition has a pH of about 7 to about 11. The invention further provides a method of polishing a substrate with the polishing composition.
1. A method for polishing a substrate comprising polysilicon, which method comprises:
(i) contacting a substrate comprising polysilicon with a polishing pad and a chemical-mechanical polishing composition consisting essentially of:
(a) about 0.5 wt. % to about 20 wt. % of silica,
(b) about 0.005 wt. % to about 2 wt. % of one or more aminophosphonic acids,
(c) about 0.001 wt. % to about 0.1 wt. % of one or more alkylated cellulose compounds,
(d) about 0.05 wt. % to about 5 wt. % of one or more tetraalkylammonium salts,
(e) about 0.01 wt. % to about 2 wt. % of potassium bicarbonate,
(f) about 0.005 wt. % to about 2 wt. % of one or more compounds comprising an azole ring,
(g) optionally potassium hydroxide, and
(h) water,
wherein the polishing composition has a pH of about 7 to about 11,
(ii) moving the polishing pad relative to the substrate with the chemical-mechanical polishing composition therebetween, and
(iii) abrading at least a portion of the polysilicon to polish the substrate.
2. The method of claim 1 , wherein the silica is wet-process silica.
3. The method of claim 1 , wherein the one or more aminophosphonic acids is present in the polishing composition in an amount of about 0.1 wt. % to about 1 wt. %.
4. The method of claim 3 , wherein the aminophosphonic acid is selected from the group consisting of ethylenediaminetetra(methylene phosphoric acid), amino tri(methylene phosphonic acid), diethylenetriaminepenta(methylene phosphonic acid), and combinations thereof.
5. The method of claim 4 , wherein the aminophosphonic acid is amino tri(methylene phosphoric acid).
6. The method of claim 1 , wherein the alkylated cellulose compound is hydroxyethylcellulose.
7. The method of claim 6 , wherein the hydroxyethylcellulose has a molecular weight of about 25,000 daltons to about 100,000 daltons.
8. The method of claim 1 , wherein the compound comprising an azole ring is a triazole compound.
9. The method of claim 1 , wherein potassium hydroxide is present in the polishing composition.
10. The method of claim 1 , wherein the substrate further comprises silicon oxide, silicon nitride, or a combination thereof.
11. The method of claim 10 , wherein the silicon oxide or silicon nitride forms an interlayer dielectric layer.