| 摘要 |
<p>1,028,095. Semi-conductor devices. SIEMENS & HALSKE A.G. Sept. 24, 1964 [Sept. 25, 1963], No. 38896/64. Heading H1K. A semi-conductor body contains a doped zone 1, a surface region 1<SP>1</SP> of which is of enhanced conductivity. Material is alloyed with the main part of the doped zone through the surface region to form a PN-junction 6. The surface region has a metallic contacting layer 4 which extends to the vicinity of the recrystallization zone 2 formed by the alloying process. The contacting layer is separated from the alloying material remaining 3 by a marginal zone in which the PN-junction is exposed at the surface of the body. In the manufacture of such devices the material of the contacting layer initially covers the entire surface of the doped region. Some of it is dissolved by the alloying material during the alloying process to leave the PN- junction exposed around the remaining alloying material. The manufacture of germanium mesa transistors is described. In one method, antimony is deposited from the vapour phase on to the doped zone and completely alloyed in to form the region 1<SP>1</SP> of enhanced conductivity. A silver layer 4 is next deposited over the entire surface of this region to form the base contact. Gold is deposited on the area where the emitter electrode is to be formed and is alloyed to form droplets and thus break the silver layer. Aluminium/gold is now deposited over the gold and alloyed to form the emitter-base junction 6 which emerges in the trough 7 surrounding the alloyed material. In a variant the initial deposition and alloying of gold alone is omitted. In another variant the layer 1<SP>1</SP> of enhanced conductivity is formed as before and the alloying material next deposited. A silver layer is deposited over the entire surface and the assembly heated to form the emitter-base junction and break the silver layer. Although the devices produced are similar, with this variant the base contact may be made thicker. In another method, a layer of silver doped with antimony is deposited on a doped region of a germanium disc. The material to form the emitter is deposited on a portion of the layer and the assembly heated to form both the layer of enhanced conductivity and the emitter-base junction. Electrode wires 8 are fixed to the devices by known thermo-compression bonding methods. A portion of the base contact may first be strengthened by deposition of metal 12. The devices are mesa etched in known manner, and may be given a purifying etch in hydrogen peroxide during which the silver layer and the emitter electrode act as masks. It is stated that the base contact layer 4 may instead be chemically or electrolytically deposited and that it may be applied as a series of different metals which are partially alloyed to the semiconductor. Instead of germanium, silicon and other semi-conductors may be used.</p> |
