Hitoshi Mishiro

Development of hard pellicle for 157 nm

Projection photolithography at 157 nm is now under research as a possible extension of current 248 nm and planned 193 nm technologies .We have found that a thin-film fused silica glass pellicle would be available to 157nm lithography because of its high durability to F2 laser irradiation . In this paper, we present the performance of the hard pellicle made of AQF. Transmission is 97.6 percent when AR films are coated on both surfaces, and its uniformity at 157.6 nm is better than +/- 0.2 percent, and birefringence is within 1 nm. We developed a new evaluation system of a hard pellicle bending in horizontal position and in vertical position. We achieved less than 1um sagging with 800um thickness membrane and glass frame made of modified fused silica in horizontal position.