Zone shape control by pattern-assisted proximity effect correction in e-beam lithography for efficiency enhancement in x-ray optics

摘要

Controlling the Fresnel zone shape is an effective way to achieve high efficiency imaging in x-ray optics. Despite significant advances toward 10-nm resolution, focusing efficiency remains a big challenge. Particularly, from the angle of e-beam lithography to control the resist profile for shaping the zones, there have been extremely limited reports so far. Our work focuses on optimizing the resist profiles in the outermost zones by a method known as pattern-proximity-effect-correction to even the exposed charge in resist. Our study demonstrates that both zone shape and the duty cycle can be deliberately controlled by lithography conditions. For a 100-nm zone plate in Au, both the aspect ratio as high as 20/1 and the duty cycle from 0.9 to 1.7 have been achieved in this work. Such a controllability enables us to enhance the focusing efficiency through zone shape control in the next effort.