掩模图形不同区域的波前因衍射光的相干叠加作用而对光刻胶上的场点产生不同的影响。为研究这一作用规律,采用波前分割的方法对掩模图形上的波前进行区域划分,并利用光场相干叠加相互抵消的性质,最终得到了掩模图形上对场点光场影响最大的波前区域。理论分析表明,对于图形内部场点而言,这个区域范围为场点附近约一个半波带的大小;而对靠近图形边缘的场点,其范围与边缘形状有关,一般要稍大于一个半波带。利用该方法可以显著提高仿真效率,对于分析由衍射造成的光刻误差来源和大小具有一定的理论指导意义。该理论计算结果得到了实验验证。

Because of the coherent superposition of the diffraction light,wave-front on different region of the mask pattern has different impact on field point in the resist. In order to analyse the contribution of these regions,a theoretical model based on wave-front division was presented. The mask pattern was divided into sub-regions and the impact of their wave-fronts on the diffraction field was investigated. For interference cancellation of the diffraction light,a special region can be finally attained,in which the wave-front has the most contribution to the field point. Study results show that,for the internal point of the pattern,the size of the region is a half-wave zone around the field point; and for points near the edge,the region is generally in a size larger than a half-wave zone,and its scope depending on the shape of the pattern. It is of great significance to improve the simulation efficiency of resist shape error caused by diffraction in lithography. Experiments have verified the calculation results.