Characterization of Chemically Amplified Resists for Electron Beam Lithography

For better understanding of electron beam resist processes, it is important to characterize the resist materials on the basis of their reaction mechanisms. In this study, the basic parameters which characterize the chemical reactions for latent image formation upon exposure to electron beam were evaluated. The electron beam resist used was a chemically amplified resist, the backbone polymer of which is poly(4-hydroxystyrene). 49% of the hydroxyl groups were protected with t-butoxycarbonyl groups. The stopping power was 0.529 eV nm(-1). The G-value of acid generation was 2.5. The effective reaction radius for deprotection was approximately 0.02 nm. The diffusion constant of acids was 1.3 nm(2) s(-1). The diffusion constant of quenchers was significantly lower than that of acids. The product of LER and chemical gradient (dm/dx) was approximately 0.06.