| 摘要 |
1300118 Semi-conductor strain transducers FERRANTI Ltd 19 April 1971 [11 March 1970] 11701/70 Heading H1K A strain transducer for detecting accelerations, forces, or fluid flow rates in one direction consists of a plurality of PN junction isolated piezo-resistive elements formed in each of two flexible semi-conductor beams. Uniform stress is achieved in the beams, which extend normal to said direction from clamped ends to a common point at which they support a seismic mass by a reduction in section of each beam at a uniform rate from the clamped end. In the embodiment which is an accelerometer P type strain sensors 13 are formed by planar diffusion into an N type epitaxial layer on a P type silicon substrate and lie along 111 and 110 crystallographic directions respectively. After diffusion and oxide passivation unwanted parts of the substrate and epitaxial layer are removed to leave two inwardly tapering beams 16 supported by a thick peripheral ring 12 and joined by an integral seismic mass 17. Aluminium tracks are then provided, which interconnect the sensors, e.g. into a bridge circuit and extend to contact pads to which fold wires are thermocompression bonded. The assembly is sealed in an evacuated housing. |
