Front-to-backside alignment using resist-patterned etch control and one etching step

A processing technique that aligns features on the front side of a wafer to those on its backside has been developed for bulk micromachining. A 30 mu m-square and 1.6 mu m-thick diaphragm serves as an alignment pattern. At the same time that the alignment diaphragm is made, much thicker, large-area diaphragms can be partially etched using 'mesh' masking patterns in these areas. The mesh-masking technique exploits the etch-rate differences between