Fabrication of High-Aspect Si Structures by Deep Reactive Ion Etching Using Hydrogen Silsesquioxane Masks Replicated by Room Temperature Nanoimprinting

Abstract

The authors developed a method of fabricating high-aspect Si structures by deep reactive-ion etching (D-RIE) using hydrogen silsesquioxane (HSQ) masks replicated by room-temperature nanoimprinting. The measured dry-etching rates of HSQ without annealing, 1000 °C-annealed HSQ, and Si when subjected to D-RIE gas sources alternately switching from SF6 to C4H8 were 20, 11.4, and 460 nm/min, respectively. This indicates that annealing generated HSQ patterns with approximately twice as much durability against dry etching; however, nonannealed HSQ patterns were shown to be sufficient dry-etching masks. We demonstrated high-aspect-ratio Si gratings 6500 nm in height with an aspect ratio of 43 by using 280-nm-high and 300-nm-pitch HSQ line-and-spacing (L/S) gratings without annealing. The results proved the suitability of HSQ-imprinted patterns as the dry-etching masks for fabricating high-aspect nanostructures.