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The effects of dissolution characteristics and acid diffusion behavior on lithographic performance were evaluated in tert-butoxycarbonyl (t-BOC)-protected chemically amplified positive deep-ultraviolet (DUV) resists. The resists consisted of t-BOC-protected polyhydroxystyrene as a base resin and 2,4-dimethylbenzenesulfonic acid derivative as a photoacid generator (PAG). In particular, the line width difference between an isolated line and a dense line (iso/dense bias) was investigated by changing the post-exposure bake (PEB) temperature. As a result, clear relationships among dissolution characteristics, acid diffusion length, and iso/dense bias were obtained. Moreover, suitable dissolution characteristics and acid diffusion length for reducing iso/dense bias were clarified.

In order to clarify the photogenerated acid diffusion in resist film, the diffusion behavior of acid, as well as the role of additional base component was investigated in tert-butoxycarbonyl (t-BOC) protected type chemically amplified positive deep ultraviolet (DUV) resists. The resists consisted of t-BOC protected polystyrene as a base resin, 2,4-dimethylbenzene sulfonic acid derivative as a photoacid generator (PAG) and N-methyl-pyrrolidone (NMP) as an additional base component. Acid diffusion coefficient was suppressed by the addition of base component. Moreover, the change of base concentration corresponded directly to the lithographic performance, such as sensitivity, resolution capability and resist profile, especially T-topping formation. Based on the experimental analysis, the clear relationship between acid diffusion length and additional base was obtained.