Self-aligned Resist Patterning with 172nm and 193nm Backside Flood Exposure on Attenuated Phase Shift Masks

摘要

We have investigated self-aligned resist patterning for a patterning accuracy of photo mask. Self-aligned resist pattern can be formed by backside flood exposure on photo-mask. It had been already proved by the experiments with 248 nm light source exposure on binary (Cr on Quartz) and KrF attenuated phase shift masks. Attenuated phase shift masks are generally composed of Cr/MoSiN/Quartz, MoSiN/Quartz, and Quartz layers. MoSiN layers of attenuated phase shift mask have the optical property of 6% transmittance at 248 nm light source, and the interference of the 6%-transmitted light makes the undesirable resist pattern profile on MoSiN-Quartz boundary. This paper shows the fresh possibility of the self-aligned resist pattern fabrication on attenuated phase shift masks using backside flood exposure. To solve the optical property of MoSiN layer, self-aligned resist patterns of KrF attenuated phase shift mask was fabricated using 193 nm wavelength backside flood exposure and ArF attenuated phase shift mask used 172 nm wavelength. The shorter wavelength than generally applied wavelength could minimize transmittance on MoSiN area. Besides we used Negative PR to make the self-aligned resist pattern on exposed regions. These experimental concepts help to form the selective PR patterning on only quartz regions of attenuated phase shift mask.