Interfacial effects on sensitization of chemically amplified extreme ultraviolet resists

With the improvement of lithography resolution in the horizontal direction, the thickness of resist films becomes thin to avoid pattern collapse. The thinning of resist films is an important issue in the development of the next-generation lithography process. In this study, the interfacial effects on the sensitization of chemically amplified extreme ultraviolet (EUV) resists were investigated using a Monte Carlo method on the basis of their sensitization mechanism. The chemically amplified resist is a standard resist used for the fabrication of semiconductor devices. In chemically amplified resists, thermalized electrons reduce sensitizer molecules upon exposure to EUV radiation. The low-energy secondary electron dynamics at the vacuum-resist and resist-underlayer interfaces strongly affected the distribution of decomposed sensitizers. In particular, the resist bulk layer almost disappeared at 20 nm pitch in the specific cases. The control of interfaces becomes important in the development of the next-generation lithography process.