Patent ID: 8685272

Claim:
A composition for etching a silicon oxide layer, consisting of: hydrogen fluoride; ammonium fluoride; an anionic polymer, wherein the anionic polymer includes at least one of polyacrylic acid, polyacrylamide, a polyacrylamide/acrylic acid copolymer, a polyacrylic acid/sulfonic acid copolymer, a polysulfonic acid/acrylamide copolymer, and a polyacrylic acid/malonic acid copolymer; an acid, wherein the acid is one of acetic acid, citric acid, formic acid, propionic acid, butyric acid, valeric acid, butylacetic acid, enanthic acid, capric acid, nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid, perchloric acid, and combinations thereof; and deionized water, wherein: the anionic polymer is included in an amount of about 0.001 to about 2 wt % based on the total weight of the composition for etching a silicon oxide layer, and the composition has an etch selectivity toward the silicon oxide layer with respect to a nitride layer of about 80 or greater.