CMP compositions and methods for suppressing polysilicon removal rates

1. A method of polishing a semiconductor substrate to remove silicon nitride in preference to polysilicon from the surface of the substrate; the method comprising abrading a surface of a silicon nitride- and polysilicon-containing substrate with a CMP composition comprising about 0.01 to about 15 percent by weight abrasive particles suspended in an aqueous carrier containing about 10 to about 10,000 ppm of a surfactant comprising an alkyne-diol, an alkyne diol ethoxylate, or a combination thereof, the composition further comprises an additive comprises potassium sulfate, wherein the aqueous carrier has a pH in the range of about 1 to about 4.

2. The method of claim 1 wherein the polishing is performed in the presence of hydrogen peroxide.

3. The method of claim 1 wherein the surfactant in the CMP composition comprises an alkyne diol compound of Formula (I) and/or an ethoxylate thereof comprising about 1 to about 40 moles of ethyleneoxy units per mole of alkyne diol compound;

Formula (I):

wherein

each of R 1 and R 2 is independently H or methyl; and

each of R 3 and R 4 is independently a C 1 to C 22 alkyl group.

4. The method of claim 1 wherein the abrading is accomplished by:

(a) contacting a surface of the substrate with a polishing pad and the CMP composition; and

(b) causing relative motion between the polishing pad and the substrate while maintaining a portion of the CMP composition in contact with the surface between the pad and the substrate for a time period sufficient to abrade silicon nitride from the surface.

5. The method of claim 1 wherein the composition further comprises about 10 to about 100,000 ppm of at least one carboxylic acid-containing additive.

6. The method of claim 5 wherein the at least one carboxylic acid-containing additive comprises malonic acid, glycine, or a combination thereof.