Component segregation in model chemically amplified resists

We have applied chemical force microscopy (CFM) to probe the surface roughness of partially developed model resist materials in order to understand the fundamental materials properties of the resists leading to line edge roughness (LER). CFM is capable of providing simultaneous information about surface topography and chemical heterogeneity of partially developed resist films. We have used CFM to study ESCAP type resists that are used in 248 nm and extreme ultraviolet (EUV) lithography. We observe changes in both the innate material roughness and chemical heterogeneity of the resist with the introduction of photoacid generator (PAG) and with exposure and post exposure bake (PEB). We find several mechanisms by which chemical heterogeneity can contribute to increasing the innate material roughness of the resist.