Comparison of photoresist sensitivity between KrF, EB, and EUV exposure

It has been reported that the good correlation in sensitivity and resolution between EUV exposure and EB exposure because of the similar mechanism of the photochemical-reaction in photoresists during exposure. However, in the early stages of EUV resist development, there are problems on the points of the cost and time-consuming to evaluate all EUV resist materials by EB exposure. Therefore, we investigated the possibility of using KrF exposure as the initial screening of EUV resists. If the correlation between KrF exposure, EB exposure and EUV exposure can be found, it will be possible to evaluate photoresists in a step-by-step manner, such as screening with KrF exposure first, followed by EB exposure, and finally EUV exposure in the initial evaluation stage. In this paper, we report on our investigations in the case of novolac resists, PHS chemically amplified resists, acrylic chemically amplified resists, and EUV polymer resists.