Analysis of acid yield generated in chemically amplified electron beam resist

Acid-related matters are a critical issue in a chemically amplified resist, in which photo- or radiation (ionizing radiation)-generated acids drive pattern formation reactions in exposed areas. The photosensitization of resist materials has been formulated by Dill et al. [IEEE Trans. Electron. Dev. 22, 445 (1975)]. The applicability of the formulation by Dill et al. to acid generation in chemically amplified photoresists has been proven by many researchers. The acid yields in photoresists are predicted well by the formulation of Dill et al. However, the formulation of Dill et al. cannot be applied to chemically amplified resists for ionizing radiation such as electron beams and extreme ultraviolet rays because polymer ionization significantly contributes to acid generation in these resists. In this study, the authors formulated acid generation in a chemically amplified resist for ionizing radiation. By the analysis of the dependence of acid yield on acid generator concentration, the details of acid generation paths were clarified.