Process for treating semiconductors

摘要

908,553. Semi-conductor devices. WESTING- HOUSE ELECTRIC CORPORATION. May 4, 1961 [June 22, 1960], No. 16205/61. Class 37. A low-resistance path is formed between two areas on the surface of a body of semi-conductor material by applying a metal layer over each area, contacting each layer with a probe, and discharging a capacitor through the layers and the region of the body lying between them, the initial charge of the capacitor being such that the semi-conductor material in the vicinity of the path of the discharge is melted. The semiconductor material may be Si, Ge, SiC, a III-V compound, e.g. InSb, InAs, GaSb, GaAs, GaP, or a II-VI compound, e.g. ZnS, ZnTe, ZnSe, and may be intrinsic or wholly or partly of P or N-type conductivity; the invention is particularly applicable to semi-conductor bodies forming unitary multifunctional devices. The capacitance of the capacitor and the charge placed upon it depend upon the semi-conductor material, its thickness, and the composition of the metal layers; for Si wafers 1-10 mils. thick a capacitance of 500-2000 ÁF. may be charged to 8-20 v. for a metal area of about 100 sq. mils. As shown, Fig. 2, foils 20, 22 comprising 99.5% Au, 0.5% Sb, are disposed centrally on opposite faces of a monocrystalline Si wafer 10 1.4 mils. thick having a P-type region 12 and an N-type region 14, and are fused thereto at about 700‹ C. in a vacuum of 10-5 mm. Hg. When cool, the foils 20, 22 are contacted by probes 32, 34 and a 900 ÁF. capacitor which has been charged to a level of 10 v. is discharged through the probes, the layer, and the wafer. This causes local melting of the wafer; the metal layer may also melt locally, or the molten Si may dissolve some metal. On cooling and recrystallization, a region 70, Fig. 4, of low resistance is formed between the foils, the PN junction 16 being destroyed within this region. A region of low resistance may be formed similarly between two areas on the same face of a semi-conductor wafer. Fig. 3 shows an arrangement comprising a double-throw switch 56 whereby a capacitor 40 can be alternately charged from a voltage divider 52 and discharged through leads 36, 38 which are connected to the probes which may be of steel or a Cu base, e.g. Cu-W, alloy. The metal layers may alternatively comprise A1, and may be in pellet form, or may be plated or vapour deposited on to the wafer.