Improving the adhesion of hydrogen silsesquioxane (HSQ) onto various substrates for electron-beam lithography by surface chemical modification

Hydrogen silsesquioxane (HSQ) is an excellent negative-tone resist for electron-beam lithography and sub-5-nm-half-pitch patterns can be achieved using high contrast development processes. However, the quality of HSQ adhesion on different types of substrates varies, thus limiting the function of HSQ in etching masks or metal lift-off process on various substrates. In this study, we proposed several chemical modification methods to improve HSQ adhesion resist onto Si, Cr, Cu, Mo, Au, and indium-tin oxide (ITO) substrates. HSQ adhesion patterns onto Au substrates was significantly improved by utilizing (3-mercaptopropyl) trimethoxysilane (MPTMS) and Poly (diallyldimethylammonium) chloride (PDDA) modifications. The (3-Aminopropyl) triethoxysilane (APTES) enhances the HSQ adhesion on Mo substrates. APTES and PDDA improve HSQ adhesion on Si, Cr, Cu and ITO. The improved adhesive HSQ nanopatterns on these substrates may benefit the fabrication of various nanophotonic and nanoelectronic devices.