Hyper-thin resist system for photomask-making in double-patterning generation

Abstract

Double-patterning generation at 32-nm node and beyond raises many subjects for photomask blanks. We especially focus on the resolution improvement by hyper-thin resist combined with the hardmask process called the hyper-thin resist system (HTRS). Cr-hardmask has been specially developed for the HTRS, and this Cr material shows an extremely high etching rate. Additionally, we confirmed that a 55-nm resist thickness was available to etch the Cr-hardmask and last then the resolution of MoSi-absorber patterns was improved by HTRS, such as 45-nm LS, 60-nm isolated line and hole, and 35-nm isolated space. Moreover, the Cr-hardmask showed almost no film stress, which is necessary to achieve the image placement accuracy required for the double patterning. MoSi-binary with HTRS meets the photomask technology requirements for 32-nm node and beyond.