Development of main chain scission type photoresists for EUV lithography

In this work, we report the lithography performance of main chain scission type resists exposed with the ASML NXE3300B EUV scanner. We also detail the advancements achieved in recent developments of the novel process conditions and the polymer properties of main chain scission type resist. With optimized resist thickness and resist developer, a resolution of 16 nm half-pitch for dense line-space pattern can be achieved with a low roughness but with a high dose over 70 mJ/cm² is required for ZER01 series (based on Zeon's resists for EB lithography). Therefore, Zeon developed ZER02 series (Zeon's novel resists) for EUV lithography, with a modified polymer structure improving the EUV absorption. The lithographic capabilities of dense Line-Space (L/S) patterns and orthogonal contact hole (C/H) patterns with ZER02#1 is presented. For L/S pattern, a resolution of 16 nm half pitch was achieved at an exposure dose of 57 mJ/cm², giving an unbiased LWR of 2.7 nm and an unbiased LER of 2.0 nm. For orthogonal C/H pattern, 44 nm pitch was resolved at 50.4 mJ/cm², with a LCDU of 3.4 nm. In addition to the enhancement of the lithographic performance achieved, fundamental studies with Gel Permeation Chromatography (GPC) and Dissolution Rate Monitor (DRM) were conducted to understand the pattering mechanism of ZER02#1 under EUV exposure.