Electron-Beam Lithography Patterning of Ge[sub 2]Sb[sub 2]Te[sub 5] Nanostructures Using Hydrogen Silsesquioxane and Amorphous Si Intermediate Layer

We report the successful electron-beam patterning of nanostructures, in the form of both lines and dots, using hydrogen silsesquioxane (HSQ) resist. Although HSQ has proven to be a good resolution electron-beam resist, the adhesion between and the HSQ resist is problematic when trying to form fine patterns. To promote their adhesion, we introduced an amorphous Si (a-Si) layer between the and HSQ layers, and the layers were then sequentially removed using reactive ion etching and Ar etching with good selectivity of each layer. The selectivities for HSQ:a-Si etched by reactive gas and etched by Ar gas were 1:2.7 and 1:17, respectively. On the basis of this multilayer structure and a two-step dry etching process, various nanostructures as small as were successfully fabricated.