Arc coating on mask quartz plate to avoid alignment error on stepper or scanner

摘要

A new method and apparatus is provide whereby light diffusion within the light measurement toll has been eliminated. A layer of Anti Reflective Coating is deposited on the outside of the second surface of a quartz mask thereby preventing light that is reflected internally to the quartz mask from exiting the mask. All reflected light is therefor eliminated and, with that, the source of light diffusion is eliminated.