| 摘要 |
1,036,165. Semi-conductor devices. STANDARD TELEPHONES & CABLES Ltd. Jan. 29, 1964, No. 3786/64. Addition to 1,023,531. Heading H1K. A device comprising a semi-conductor wafer with at least one contact comprising a layer grading outwards from an adherent to a softsolderable metal and extending from a semiconductor zone on one face over an insulating layer thereon has its contacts soldered to the lead wires of a header. In an embodiment, a planar transistor, Fig. 1, made in multiple by successive diffusions into a silicon wafer through apertures formed in a surface oxide layer by photo-resist etching techniques, is provided with an overall film of aluminium. This is removed, except from areas of the emitter, base and collector zones exposed through apertures in the oxide film, by photo-resist etching techniques. An overall film graded from chromium beneath to gold above is then deposited as described in Specification 1,010,111 and reduced to strips 9, 10, 11 in contact through the aluminium with the collector, base and emitter zones respectively. The transistor is dipped in flux and then in a lead-tin eutectic or a commercial silver solder to tin the strips which are next soldered to the flattened ends of wires 13 extending from header 12 (Fig. 4). Alternatively, the wires terminate on the header surface in graded chromium-gold films to which the strips are soldered. The transistor is sealed by welding a top cap to the header flange. Prior to or as alternative to this an opaque insulating coating may be provided, e.g. by transfer moulding. Suitable coating materials are rubber, nylon, polypropylene, and epoxy and silicon resins, incorporating alumina or glass as fillers to match the expansion coefficient to that of silicon. Successive coatings of different materials may be applied, and to assist cooling a block of copper may be embedded in the coating. In an alternative method of making the transistor, the aluminium contacts are replaced by nickel or omitted. If the diffused regions are formed in a high resistivity layer epitaxially grown on a heavily doped silicon wafer, the collector contact may be deposited in a groove cut through the oxide and epitaxial layers. Application of the invention to silicon controlled rectifiers and diodes and to germanium devices incorporating a silicon oxide coating is also suggested. |
