Method for manufacturing semiconductor strain sensor

摘要

A semiconductor strain sensor has a semiconductor substrate having a pair of major surfaces parallel to each other. The substrate is worked to constitute a frame and a thin diaphragm by forming a circular blind hole from one major surface. The bottom surface of the blind hole is formed in a conical shape projecting upward from the edge portion to a central portion thereof. The substrate has a thickness of not less than 0.5 mm and not less than about five times that of the diaphragm. The blind hole is formed by grinding and the inner surface of the blind hole is then etched to eliminate a scratch formed in the inner surface by grinding. Resistance layers are formed on the other major surface of the substrate. Each layer has a piezoresistance which varies in accordance with the pressure applied to the diaphragm.