COMPOSITION AND METHOD FOR POLISHING POLYSILICON
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 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 polysaccharides,
(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 a bicarbonate salt,
(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.
2 . The polishing composition of claim 1 , wherein the silica is wet-process silica.
3 . The polishing composition of claim 1 , wherein the polishing composition contains about 0.1 wt. % to about 1 wt % of one or more aminophosphonic acids
4 . The polishing composition of claim 3 , wherein the aminophosphonic acid is selected from the group consisting of ethylenediaminetetra(methylene phosphonic acid), amino tri(methylene phosphonic acid), diethylenetriaminepenta(methylene phosphonic acid), and combinations thereof.
5 . The polishing composition of claim 4 , wherein the aminophosphonic acid is amino tri(methylene phosphonic acid).
6 . The polishing composition of claim 1 , wherein the polysaccharide is hydroxyethylcellulose.
7 . The polishing composition of claim 6 , wherein the hydroxyethylcellulose has a molecular weight of about 25,000 daltons to about 100,000 daltons.
8 . The polishing composition of claim 1 , wherein the compound comprising an azole ring is a triazole compound.
9 . The polishing composition of claim 1 , wherein potassium hydroxide is present in the polishing composition.