Optimization method of scanning strategy for reactive ion beam etching of large aperture grating elements

Large-scale two-dimensional gratings are typically produced using reactive ion beam scanning etching. However, this method is limited by uneven etching depth, which can negatively impact the performance of large-aperture gratings. To address this issue, we propose optimizing the scanning strategy during reactive etching to improve uniformity. Based on the specific beam distribution, we have established a row spacing calculation model using the convolution algorithm. In the actual reaction etching experiment, we found that a row spacing of only 16 mm resulted in a uniformity within the etching range of 600 mm that was better than 6%. This improvement enhances the diffraction uniformity of the grating. Simulation and experiment were used to verify the influence of row spacing on the uniformity of surface grooves during etching. This method was then used to significantly improve the uniformity of grating etching depth after processing. Therefore, the proposed optimization method of reactive etching scanning strategy has a good industrial application prospect for large-scale two-dimensional grating, wafer etching, and large-scale integrated circuit manufacturing.