A measurement free pre-etched pattern to identify the < 110 > directions on Si{110} wafer

摘要

In this paper, we present a self-aligning pre-etched pattern based technique to precisely determine the < 110 > direction on Si{110} wafer surface. These patterns after etching, reveals the crystallographic direction by self-aligning itself in a straight line at the < 110 > direction while getting self-misaligned at other directions. As a result, the exact direction can be identified by a simple visual inspection under a microscope without the need of measurement of any kind. To test the accuracy of the proposed method, we fabricated two 32 mm long channels, one oriented along the < 110 > direction and other along the < 112 > directions using the < 110 > direction obtained from the proposed method as the reference. The undercutting is measured at different locations on the two channels and is found to vary within a submicron range in each case. Such uniform undercutting implies that the presented technique to determine the < 110 > direction is accurate. This methodology is simple and can be used conveniently to fabricate MEMS structures with high dimensional accuracy.