SEMICONDUCTOR STRAIN GAGE AND METHOD OF FABRICATING SAME

A piezoresistive semiconductor strain gage for transforming mechanical stress into a changed resistance of the semiconductor and therefore a changed electrical current therethrough representative of the amount of stress is described. Also described is a method of fabricating the strain gage that is reliable and results in each produced strain gage having the characteristics of all of the others. The strain gage is comprised of a piezoresistive silicon body having enlarged ends. A KOH etch is made in each end and an epitaxial layer is therein. THEREIN. The epitaxial layer is of the same conductivity type as the piezoresistive silicon but is much more heavily doped to provide low resistance paths to solderable contacts connected to the epitaxially grown material. The combination of enlarged ends and reduced center provides stress amplification, resulting in a greater sensitivity of the strain gage.