Hydrogen silsesquioxane a next generation resist for proton beam writing at the 20 nm level

In proton beam writing (PBW) the only compatible resists which have demonstrated sub-100 nm features are PMMA and SU-8. In this paper, we present results on PBW using a new non C based, hydrogen silsesquioxane (HSQ) resist. The results obtained with PBW using the HSQ resist, show that HSQ behaves as a negative resist under proton beam exposure. Details down to the 20 nm level in width standing at a height of 850 nm have been directly written in HSQ. The superior resolution of HSQ shows great potential but unlike PMMA and SU-8 this resist has a limited shelf life. To optimize the usage of this resist contrast curves and sensitivity of HSQ as a function of shelf life will be discussed. The quest for smaller feature sizes is further complicated by the fact that the beam size determination has an error of about 14 nm.