Pattern Alignment Effects in Through-Wafer Bulk Micromachining of (100) Silicon

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Precise alignment of the mask patterns relative to wafer crystallographic orientation is critical in the fabrication of many MEMS devices. Slight misalignment between the two can create striations and other defects in the etched sidewalls using an orientation dependent etchant such as potassium hydroxide (KOH). This paper focuses on the characterization of the resultant geometries due to the deliberate misalignment of photolithographically defined patterns relative to the (110) plane in (100) orientation silicon. The surface roughness of the etched (111) sidewall are characterized using optical microscopy, scanning electron microscopy and profilometry.