Study on radiation-induced reaction in microscopic region for basic understanding of electron beam patterning in lithographic process (I) - Development of subpicosecond pulse radiolysis and relation between space resolution and radiation-induced reactions of onium salt

In the acid generation processes of chemically amplified electron beam and X-ray resists. the ionization of a base resin plays an important role. A proton is generated from the cation radical of the base resin. On the other hand. it counter anion is generated from an acid generator after the reaction of the acid generator with the electron generated by the ionization of the base resin. In the resist materials in which both the radical cation of base resin and the electron play important roles in forming a latent image, the initial separation distance between the cation radical anti the electron and the subsequent reactions immediately after irradiation are important for the fabrication of nanoscale patterns. For the understanding of electron beam and X-ray patterning, we developed a subpicosecond pulse radiolysis system for conducting the absorption spectroscopy and investigated the reactions of onium salt. The onium salt efficiently reacts with an electron generated by ionization. The high efficiency of reaction of an onium salt with an electron is thought to block the migration of it thermalized electron in the resist matrix and prevent the degradation of the space resolution of resists caused by the migration of the thermalized electron.