A new pre-etching pattern to determine < 110 > crystallographic orientation on both (100) and (110) silicon wafers

Abstract

Since the etching rate of anisotropic wet etching of silicon is highly orientation-dependent, it is important to determinate the crystallographic orientation before etching. In this paper, a new mask pattern based on the pre-etching process is designed to find out the <110> crystal orientation on both (100) and (110) silicon wafers observably and to align the subsequent masks more easily and conveniently. Because of a compensation of the quantization error due to the limitated scanning resolution of a mask generator and an optimum design, a pre-etching mask pattern with a resolution of 0.00625degrees and a span angle of +/-2degrees is achieved with a consumption area of 560 x 14,472 mum(2). To evaluate the precision of the misorientation angle determined by the pre-etching process based on the proposed pattern, both (100) and (110) wafers with 60 pre-etching patterns on each of them were etched. After statistic analysis, the precision of +/-0.0467degrees for (100) wafers and +/-0.025degrees for (110) wafers are achieved in our experiments which suggest the precision of determination of the crystallographic misorientation by the preetching process may be limited even though the resolution of the pre-etching mask pattern is high.