Form of Deprotection in Chemically Amplified Resists

The push to mass production of patterns with sub-100 nm dimensions will require nanometer level control of feature size, including line edge roughness (LER). Control of LER and sidewall roughness within the length scale of individual molecules requires a fundamental understanding of LER formation. For chemically amplified resists, image quality is controlled in part by the diffusion and reaction of small molecule photogenerated acids within the resist. Using Small Angle Neutron Scattering (SANS) we provide a direct measurement of the form of the deprotection path created by individual acid molecules common to chemically amplified resists. The deprotection path is characterized as spatially heterogeneous, forming a "fuzzy blob". A fundamental factor of LER formation is therefore the packing of these "fuzzy blobs" within the resist, and their subsequent reaction with the developer. Efforts to describe this packing are briefly discussed.