极紫外投影光刻掩模的多层膜与照明误差

Multilayers on Extreme Ultraviolet Lithography Masks and Illumination Error

讨论了极紫外投影光刻掩模的反射光谱随多层膜参量的变化,通过曲线拟合得到了峰值反射率、带宽和中心波长与多层膜粗糙度、材料比值以及周期厚度的9个函数关系·模拟了6镜极紫外投影光刻系统的反射光谱,并计算了晶圆片处的相对照明强度·分析了由掩模在晶圆片处引入的照明误差,给出了照明误差的合成公式·

The peak reflectivity, bandwidth and centroid wavelength of Extreme Ultraviolet Lithography （EUVL） Mask as a function of roughness, period thickness and thickness ratio of Mo/Si multilayers were calculated. Nine equations were obtained by fitting the calculated data. Then, the reflective spectrum of 6- mirror EUVL system were simulated, and calculation were performed to work out the relative illumination intensity at wafer plane. Finally, illumination uniformity error at wafer plane induced by the mask were analyzed, and resulted a formula for estimating the error.