为了检测全息光栅掩模槽形,运用严格耦合波理论(RCWT)分析镀铬基片光栅光刻胶掩模反射0级衍射效率光谱曲线与槽形参量的关系。测量了400～700 nm波长范围内60°入射角条件下的镀铬基片全息光栅光刻胶掩模反射0级衍射效率光谱曲线。将实验曲线与不同槽形参数对应理论曲线相减、求标准差进行匹配,标准差最小者为匹配结果,从而找到被测掩模的槽深和占宽比(光栅齿宽占光栅周期的百分比)。结果表明,该方法图形匹配速度快,误差容限大,匹配结果与电镜结果相符。对于要求同时检测矩形或接近矩形槽形的全息光刻胶光栅掩模的槽深和占宽比,该方法完全适用。

In order to detect the profile of holographic photoresist grating mask made on top of chrome stack, rigorous coupled wave theory (RCWT) was applied to analyze the relationship between zero order reflected spectrum and the profile of grating mask. Zero order reflected spectra range from 400 nm to 700 nm at the incident angle of 60° were measured in experiment. The standard deviation of differences between experimental curve and theoretic curve of different profiles is calculated for matching,and the duty cycle and groove depth were obtained by the best fitted theoretic spectra corresponding to minimum standard deviation. Results achieved in this way which is a quick in matching and high in error tolerance, agree very well with scanning electron microscope (SEM) pictures. The method is qualified for measurement of groove depth and duty cycle simultaneously for the rectangle-shaped or similar profile of holographic grating mask.