High-frequency mesa transistors

摘要

1,011,502. Semi-conductor devices. SIEMENS & HALSKE A.G. June 25, 1964 [June 27, 1963], No. 26244/64. Heading H1K. A diffused-base mesa transistor has parallel rectangular base and emitter electrode stripes 4 and 5 respectively of length not greater than 47 Á and width not greater than 18 Á formed on the mesa plateau 10, with leads in the form of gold wires 7 and 8 of diameter 12Á or less attached to the electrode stripes. As shown, the base layer 3 of a PNP transistor is produced by the diffusion of antimony into a wafer 1 of germanium P-doped with indium or gallium and the emitter zone 6 is formed by alloying the vapour-deposited gold and aluminium electrode stripe 5. The base electrode stripe 4 is of gold and silver, the width of each stripe being about 15 Á and the length 40 Á, and the distance between the two stripes being 10 Á. The eccentrically-located mesa is square with a side length of between 60 Á and 70 Á. An ironcobalt-nickel collector electrode 2 is soldered on by means of an indium-gallium alloy containing 0.5% by weight of gallium. Gold wires 7 and 8 of diameter 8 Á are attached by thermocompression bonding to the emitter and base electrode stripes at points at least 5 Á from the germanium surface 10 and these contact points 9 are then covered with a light silicone varnish which is burnt in. The transistor is encap sulated in a housing which is filled with a silicone oil containing a molecular sieve as a siccative.