Application of zirconium silicon oxide films to an attenuated phase-shifting mask in ArF lithography

We have investigated the durability under ArF excimer laser light of bi-lay er zirconium silicon oxide (ZrSixOy) films used as the shifter of an attenu ated phase-shifting mask (Att-PSM). We have achieved excellent stability by using the structure of the transparent film (TF) on the absorptive film (A F) rather than the structure of AF on TF. We can estimate a sufficient life time of more than three years in mass production for TF/AF/quartz structure . By XPS analysis, it has been clarified that the surface of TF is stable t o ArF irradiation and the surface of AF is easily oxidized by the irradiati on. TF/AF/quartz is the optimum structure for the prevention of surface oxi dation. 0.13 mum line patterns have been achieved with a sufficient process margin by using optimized bi-layer ZrSixOy films as an Att-PSM and off-axi s illumination in ArF lithography.