forming an insulating layer on a semiconductor substrate;

forming an opening in the insulating layer;

forming a protected layer on an upper surface of the insulating layer and a lower surface and sidewalls of the opening;

forming a buffer layer on the protected layer, the buffer layer filling the recess and including a major portion of a copolymer polymerized with monomers including from 61 to 75 weight percent benzyl methacrylate; from 8 to 15 weight percent alkyl acrylic acid; with a balance being hydroxy alkyl methacrylate;

removing an unexposed upper portion of the buffer layer using a developer solution to expose an upper portion of the protected layer, a remaining portion of the buffer layer substantially filling the recess; and

removing the upper portion of the protected layer while a lower portion of the protect layer is protected by the remaining portion of the buffer layer,

wherein the variables L, M and N represent the relative molar fractions of the monomers and satisfy the expressions

0<L≤0.8;

0<M≤0.25;

0<N≤0.35; and

L+M+N=1; and, wherein

R¹, R² and R³ are independently selected from C₁-C₄ alkyls and derivatives thereof.