Elimination of proximity effect in photoresist

摘要

The proximity effect in photoresist patterns has been eliminated by carefully controlling the values of three independent variables that are involved in the photolithographic process. These are the temperature at which Post Exposure Bake is performed, the numerical aperture of the exposure system and the partial coherence parameter. Specifically, the Post Exposure Bake temperature should be 20-25 DEG C. lower than that recommended by the manufacturer, the numerical aperture should be around 0.5 and the partial coherence parameter around 0.8. If these guidelines are followed, no proximity effect is in evidence down to duty ratios less than 1 and distortion-free patterns are obtained without the need for an Optical Proximity Correction.