TRANSISTOR DE PUISSANCE POUR MICRO-ONDES

摘要

1277863 Transistors RCA CORPORATION 24 Nov 1970 [20 Feb 1970] 55715/70 Heading H1K A power transistor comprises an annular base region which surrounds part of a collector region of opposite conductivity type at one face of a semi-conductor body. The base region consists of an inner annulus of high resistivity material with a plurality of radial lobes extending therefrom separated by inwardly tapering wedges of low resistivity material which merge into a peripheral ring. A plurality of emitter regions is provided each disposed in one of the lobes. In the embodiment (Fig. 1) a central emitter electrode deposited over a silicon oxide layer on the silicon body contacts all the emitter regions via slots in the oxide, the base electrode overlies the base region ring and has opposed bonding pad extensions on the oxide and the collector electrode is on the back face of the body. Several such structures may be formed side by side in the same body sharing bonding pads to which aluminium connecting wires are bonded. Alternatively the emitter electrodes are thickened to allow face bonding to a substrate with base and emitter connections on different levels. As described the collector region is an N epitaxial layer on an N+ silicon substrate and the two parts of the base and the emitter region formed in successive standard masked diffusion steps, boron nitride being used as the diffusant source for the base region. Electrodes are formed of aluminium by vapour deposition and formetching.