Halbleiter-Anordnung mit gut loetbaren Kontaktelektroden

摘要

1,207,010. Electrodes for semi-conductor devices. SEMIKRON GESELLSCHAFT FUR GLEICHRICHTERBAU UND ELEKTRONIK m.b.H. 2 Dec., 1968 [1 Dec., 1967], No. 57002/68. Heading H1K. An electrode is applied to a semi-conductor body 1 by applying a first layer 2 of a non- precious metal such as Al or Mg, a second layer 3 of a ductile metal such as Ag, Pd or Cu and a barrier layer 5 of a metal such as Ni, Co, Cr, Ti or Mn which inhibits the migration of the metal of the first layer 2 to the free surface of the electrode during alloying or subsequent soldering. The free surface itself comprises a precious metal. The barrier layer 5 may be situated as shown on top of the ductile layer 3, in which case its inhibiting action is due solely to the relatively low diffusion rate of the metal of layer 2 through the barrier layer 5. In addition this arrangement also requires the provision of a further protective layer 6 of a precious metal, e.g. of Au, Ag or Pd. The electrode is completed by heating to produce a ternary alloy zone 4 comprising the metals of layers 2 and 3 and the semi-conductor material, which may be Si, Ga or GaAs. In an alternative form the barrier layer 5 is situated between the layers 2 and 3 and forms a fourth component in the alloyed zone 4. The barrier layer 5 may also be situated between two successively deposited laminae (31, 311), Fig. 3 (not shown), which together constitute the ductile layer (3). The layer (5) may, in this case, be positioned either within or outside the alloying zone (4b or 4a respectively). The various metal layers may be applied by vapour deposition, cathode sputtering or plating. Electrical connections may be hard soldered to the free surface using Au/Sn, Au/Ge or Au/Si alloys. The invention may be applied to rectifiers, transistors or semi-conductor lazers and oscillators. It is also applicable to the formation of connections to electrical conductors, e.g. on semi-conductor devices.