Michael R. Heslin

New photomask substrate for improved lithography performance

As we enter the deep sub-wavelength lithography regime, using the 193 nm wavelength for the 130 nm node and beyond, the often overlooked mask material properties are beginning to have an impact on imaging performance. By analyzing properties such as index of refraction homogeneity and stress birefringence it was found that a wide variation exists within the available population of mask materials. The investigation of these materials demonstrated the considerable range in performance that can be achieved from the population of mask materials. We will show that due diligence in the selection of the mask material will provide the ability to image multiple features with a reduction in Mask Error Enhancement Factor and improved critical dimension uniformity on the wafer.