Integrated heat management in the reticle masking module on the LITEQ 500 projection stepper

A reticle masking module with integrated heat management for the Kulicke & Soffa LITEQ 500 projection stepper is described in this paper. This device allows a small portion of the 52 mm x 33 mm reticle field to be selected for exposure. Additionally, it provides air cooling for both the reticle and the reticle masking blades. This function reduces the impact of reticle expansion and air turbulence on the quality of the photolithographic image. Improvement is demonstrated by measurements with an aerial image sensor and by overlay analysis of the resist images.