Semiconductor device and method of making same

摘要

1,133,376. Semi-conductor rectifiers. RADIO CORPORATION OF AMERICA. 23 May, 1966 [9 June, 1965], No. 22856/66. Heading H1K. A plurality of junction-containing semiconductor wafers are bonded in series in a stack by intervening conductive layers, the lateral surfaces of the wafers being protected by oxidic insulating material overlying which is a different insulating material. Suitable semi-conductors are silicon, germanium, and AIIIBV compounds such as gallium arsenide. Junction-containing wafers 10 may be produced from wafers of one conductivity type by single or double diffusion or by epitaxial growth. Conductive material 24 may be applied as a foil to one side of each wafer, or a conductive layer may be formed by evaporation, plating, spraying on a suspension of powdered material, or by dipping the wafer in powdered material. Conductive materials mentioned are chromium, niobium, palladium, platinum, silver, tantalum, titanium, or zirconium, and germanium and germaniumsilicon alloys. The wafers 10 are stacked between degenerate wafers 22, 23 and hot pressed in the neutral or reducing atmosphere of an induction furnace at specified temperatures and pressures to bond the stack by diffusion of conductive material into the semi-conductor. Grooves are then formed in the stack (Figs. 5, 6, not shown) by chemical or electrolytic etching, sawing, grinding, or ultrasonic machining to produce several stacks of square or circular cross-section united at one end by the remaining material of one of the degenerate wafers 22. As illustrated in the remaining Figures (not shown) an overall silicon dioxide coating (44) is formed by oxidation of the semi-conductor (when appropriate), by evaporation of the oxide, by decomposition of organosilanes, or by hydrolysis of hydrides or halides. (With germanium and gallium arsenide bodies the silica coating may contain phosphosilicate, borosilicate or lead silicate materials.) The grooves are now filled with glass (46) by pressing softened glass against the stacks (or by sedimentation or vapour deposition) and separate stacks produced by cutting through the glass and degenerate substrate. The degenerate material at each end of a stack is exposed, metal-plated (e.g. with nickel by electroless plating), and solder-coated. Electrode blocks (66, 68) of silver or copper are then attached. The stack is completed by a coating (70) of epoxy resin or silicone resin.