消除数字光刻像素栅格衍射影响的研究

提出用优化成像系统设计参量的方法有效消除基于数字微镜阵列的栅格结构及其衍射对微结构成像质量的影响.模拟结果表明,当照明光源的波长为0.365 μm,系统的数值孔径为0.3左右,缩小倍率为10～20×时,栅格像的可见度在0.1以下,DMD的栅格结构对成像质量的影响大幅降低;对微透镜的成像分析发现,合理的成像系统结构参量能有效地减少栅格的影响.如果结合DMD显示图形的可编程特点,优化图形的结构或灰度,则能在像面获得较理想的曝光量分布,达到快速加工二维和三维微结构的目的.实验结果证实了优化系统参量可有效消除DMD栅格的影响.

Removal of Pixel Structures by Optimizing the Parameters of Imaging System in Digital Photolithography

The pixel structure is removed by optimizing the parameters of imaging system rather than other techniques that make the setup of digital photolithography complexity.The simulation results show that the pixel structure can be effectively deduced when numerical aperture(NA) is 0.3 and demagnification factor(DF) is from 10× to 20× with 0.365 μm illumination wavelength.The analysis of aerial images of practical microstructures shows that the parameters above have different effects on binary and gray-tone patterns.Arbitrary binary pattern can be fabricated without any correction if DF is in the range of 10×～15×.However,the imaging quality of gray-tone pattern is greatly worsened for the parameters above,but it can be improved by use of the feature of programmable DMD.Finally,the experimental results demonstrate the parameters are suitable for removing pixel structure.