用灰度曝光技术改善数字光刻图形轮廓

基于空间光调制器(SLM)数字光刻技术可用于IC掩模制作或直接作为微结构的加工工具,但用数字投影光刻系统加工某些结构的二元图形时,往往难以获得预期的图形轮廓,即图形边缘处有一定畸变,特别是较低缩小倍率时。本文提出优化设计图形边缘灰度的方法来校正光刻图形的畸变。文中分析了数字光刻制作这些二元光刻图形时空间像畸变产生的物理机制,详细讨论了设计图形边缘灰度优化的规则,并以加工圆孔滤波器为例,模拟了它的数字光刻成像过程。结果表明,设计图形的边缘采用灰度曝光可使其空间像畸变减小约8个百分点,光场分布更为均匀。数字灰度曝光技术简单易行,可为改善光刻图形质量提供了新途径。

Improving the edge profiles of lithography patterns using gray-tone technique in digital photolithography

Digital photolithography based on Spatial Light Modulator (SLM) is used to fabricate IC mask and microstructure, which employs a computer controlled SLM as a switchable projection mask. However,the edges of the imaging patterns will deviate from those of the designed patterns when it is used for binary lithography to fabricate some microstructures especially using a low-demagnification lithography objective. In this paper,a new method with gray levels to correct the aberrations was developed. The generating mechanism of the aberrations and the correcting rules were discussed in detail. The simulation results of the fabrication of circular wave filter show that the imaging pattern quality after correction is clearly better than that before correction and the aberration is reduced about 8%. The method is simple and provides a new way to improve the imaging quality in digital photolithography.