〈111〉晶向标定方法及其在湿法刻蚀硅光栅中的应用

Calibration method of silicon〈111〉orientation and its application in fabrication of silicon grating by anisotropic wet etching

在利用单晶硅的各向异性腐蚀制作光栅的过程中,掩模与硅晶向的精密对准是获取大尺寸光栅结构的前提条件,高对准精度将显著降低光栅槽型侧壁粗糙度。设计并制作了一种扇形图案,通过以该图案为掩模的预刻蚀,可快速准确发现硅基底内晶格取向。通过此方法进行晶向标定,并利用紫外光刻与湿法刻蚀,成功研制了尺寸为15mm×15mm、高度为48.3μm、周期为5μm、高宽比为20的矩形光栅结构,线条侧壁粗糙度RMS值为0.404nm;利用全息光刻与湿法刻蚀成功研制了大高宽比深槽矩形光栅及三角形槽光栅。矩形槽光栅尺寸为50mm×60mm,高度为4.8μm,周期为333nm,高宽比为100,侧壁粗糙度RMS值为0.267nm。三角形槽光栅周期为2.5μm,侧壁粗糙度RMS值为0.406nm。

Gratings with many types of groove profiles such as rectangles and triangles can be fabricated by wet etching silicon,during which a key step is to accurately align the grating line of the mask with the 〈111〉orientation of silicon.Sidewall roughness can be visibly reduced by highprecision alignment,which is necessary for the fabrication of large grating structures.A fanned alignment pattern was designed and fabricated,which was then etched to accurately determine the〈111〉orientation of silicon.After determining the 〈111〉orientation,agrating with a height of48.3μm,period of 5μm,and area of 15 mm×15 mm was fabricated successfully by ultravioletlithography and wet etching.The aspect ratio of the grating was approximately 20,and the roughness of the lines＇sidewalls was 0.404 nm.A rectangular grating with a large aspect ratio and a triangulargrooved grating were fabricated successfully with holographic lithography and wet etching.The rectangular grating was 4.8μm tall with a period of 333 nm and an area of 50 mm×60 mm.Its aspect ratio was approximately 100 with a sidewall roughness of 0.267 nm.The period of the V-groove grating was 2.5μm,and its sidewall roughness was 0.406 nm.