Difference of Spur Distribution in Chemically Amplified Resists upon Exposure to Electron Beam and Extreme Ultraviolet Radiation

In chemically amplified resists, acid generators are sensitized mainly by secondary electrons upon exposure to an electron beam (EB) or extreme ultraviolet (EUV) radiation. Therefore, the reaction mechanisms of EB and EUV resists are analogous. In addition to the difference in the absorption coefficients and related phenomena, the major difference between EB and EUV resists is the energy spectrum of secondary electrons generated by incident radiation. Both an EB and EUV radiation generate ion pairs through ionization in resist films. The space that an ion pair occupies is called a spur. When spurs overlap, the electron dynamics changes and affects the chemical yield and distribution. In this study, the distribution of intermediate species in EB and EUV resists was investigated by a Monte Carlo simulation. The difference between their spur distributions and its effects were clarified. To calculate the acid distribution in chemically amplified resists, the single-spur model is generally sufficient for EB resists, while the multispur model is required for EUV resists.