| 摘要 |
<p>885,137. Semi-conductor devices. PHILIPS ELECTRICAL INDUSTRIES Ltd. Sept. 13, 1960 [Sept. 16, 1959], No. 31494/60. Class 37. A semi-conductor device has an electrode comprising aluminium which has been coated by electroless plating with a layer of nickel and/or cobalt. In one example, an aluminium electrode 2 (Fig. 5), is fused to a P-type silicon wafer 1 at 780‹ C.; the whole is then etched in nitric and hydrofluoric acid, washed and placed in an electroless bath of nickel chloride, sodium hypophosphite, ammonium chloride, sodium citrate and water for 15 minutes at 90‹ C. to provide a nickel coating. Alternatively, cobalt may be applied utilizing a bath of cobalt chloride, sodium hypophosphite, Rochelle salt, ammonium chloride and water. The electrode is then tin-soldered to a support 6 and the nickel coating removed from the opposite surface of wafer 1 to which a point contact 7 or one or more other electrodes may be applied. The assembly is then sealed in an envelope 8. In a second embodiment a rectifying contact is provided by alloying an oxide-coated aluminium wire 11 (Figs. 13 and 14) to an N-type silicon body at 750‹ C. in hydrogen. The assembly is etched in HF and HNO 3 to remove the oxide film, and placed in an electroless plating bath as before to provide a nickel coating over the wire and the silicon. To remove the nickel from around the NP junction perimeter, a portion of the wire is plated with tin 17 and wax 22, and the opposing surface of the silicon is stuck with wax 18 to a glass plate. The rectifier is then etched in HF and HNO 3 which removes the nickel from the unprotected surfaces. Fig. 14 shows the completed device with wire 11 with endcoating 17 of nickel and tin connected to a ferro-chromium tube 27.</p> |
