Understanding the Role of Acid vs. Electron Blur in EUV Resist Materials

Abstract

Further development of a polymer-bound PAG resist system is discussed. For 28nm hp, we obtained 26% exposure latitude and 0.3 micron DOF at a sensitivity of 17.1 mj. We also obtained 20nm half pitch resolution under dipole conditions. We have undertaken to deconvolve the blur sources in EUV as well. The total diffusion blur of an EUV resist exposed under ArF exposure conditions was estimated to be 10.6nm, with 9.3nm of the blur coming from acid reaction-diffusion and 4.3nm coming from the radius of gyration of the polymer. The total diffusion blur of the same resist material under EUV exposure conditions is 11.5nm. We get an EUV-specific blur contribution of 2.5nm associated with the acid cloud generated from the electrons generated after an EUV photon hits the polymer matrix, and a presently undefined blur contribution of 3.7nm which is probably contributed from the flare of the optics, and possibly from out-of-band radiation. The polymer-bound PAG resist has effectively a 9.7nm diffusion blur contribution which should be improved to less than 8 nm for 16nm node.