Semiconductor strain gauge

Abstract

Abstract 923,153. Measuring electrically. FAIRCHILD SEMICONDUCTOR CORPORATION. June 27, 1961 [Aug. 18, 1960], No. 23175/61. Class 40 (1). [Also in Group XXXVI] A strain gauge comprises a wafer of semiconductor material suitable for mounting upon a test member, at least one strip in the wafer being doped and provided with spaced contacts so that it may be connected in a measuring circuit to indicate variations in the resistance of the strip or strips with strain. As shown, Figs. 1, 2, a wafer of monocrystalline semiconductor material, e.g. P-type Si, comprises on one surface two N-type sensor strips 13, 14 formed by diffusion and disposed in parallel and in alignment with one of the crystal axes. A protective layer 18, e.g. of SiO 2 is formed over the said surface and edges of the wafer; it is etched away or otherwise removed to provide access to the ends of the sensor strips, ohmic metal contacts 19, 191 and 20, 20<SP>1</SP> being alloyed to said ends. A " rosette " gauge (not shown) comprises a plurality of sensor strips extending in different directions from a central point. The wafer may be of intrinsic conductivity. In operation, the device may be bonded to the test member 41, Fig. 4, by alloying using an alloying agent 42, e.g. Au, each sensor strip being electrically insulated from the member 41 by the P-N junction it defines or, in the case of an intrinsic wafer, by the high resistivity of the latter. Alternatively, conventional cements may be used for bonding. The two sensor strips 13, 14, of Fig. 1, may form opposite arms of a Wheatstone bridge measuring circuit.

Inventors

No inventors recorded.

Bibliographic Details