Underlayer composition and method of manufacturing a semiconductor device

A method of manufacturing a semiconductor device includes forming a underlayer over a substrate. The underlayer includes a polymer, including a main polymer chain having pendant target groups, and pendant organic groups or pendant photoacid generator groups. The main polymer chain is a polystyrene, a polyhydroxystyrene, a polyacrylate, a polymethylacrylate, a polymethylmethacrylate, a polyacrylic acid, a polyvinyl ester, a poly(methacrylonitrile), or a poly(methacrylamide). Pendant target groups are substituted or unsubstituted C2-C30 diol group, C1-C30 aldehyde group, or C3-C30 ketone group. Pendant organic groups are C3-C30 aliphatic or aromatic groups having at least one photosensitive functional group, and pendant photoacid generator groups are C3-C50 substituted aliphatic or aromatic groups. A photoresist layer is formed over the underlayer. The photoresist layer is selectively exposed to radiation. The exposed photoresist layer is developed to form a pattern.