Semiconductor devices

摘要

Selected portions of a semi-conductor body are plated by abrading the portions to provide preferentially platable areas and then immersing the entire body in a plating bath; an oxide coating may be used as a mask, the pattern being produced by abrading (or etching) the oxide layer in the preferential areas. Fig. 1 shows a germanium body 10 with mask 12 being subjected to alumina particles projected form an argon jet 22. The body is then deposited in a plating bath so that metal adheres only to the abraded portions of the surface and heated to fuse the surface metal to provide an ohmic or rectifying contact. Fig. 12 shows a continuous length of dendritic crystalline semi-conductor 76 being passed in front of an intermittent nitrogen abrasive jet 74 and then into bath 82 which deposits indium on the abraded regions. The crystal passes into a heating chamber 88 which fuses the indium and in front of nozzle 94 which abrades portions of the opposite surface of the crystal. The abraded areas are plated with gold in bath 100 and heating, attachment of leads or other processes are subsequently performed in region 106 where individual semi-conductor devices may be separated from the continuous strip. In a modification, the surface of the semi-conductor is covered with an oxide layer before abrasion. The semi-conductor may consist of silicon, germanium, or an Aiii Bv compound. Abrasion may be effected by liquid or gas jets (carrying abrasives such as particles of alumina, silicon carbide, silicon, germanium, or diamond), ultrasonic vibrations of a liquid medium, abrasive or cutting wheel, abrasive drill or lapping. Plating may be effected by electroplating, displacement plating or chemical reduction. Details of the composition of baths are given for plating silicon or germanium with one or more layers of indium, silver, copper, gold, lead, antimony, gold-antimony alloy, aluminium and thallium. Two or more metals may be deposited simultaneously or sequentially. A further doping impurity may also be added by evaporation, ionic beam or gaseous deposition.