| 摘要 |
1,110,993. Semi-conductor devices. STANDARD TELEPHONES & CABLES Ltd. 9 Jan., 1967, No. 1201/67. Heading H1K. In a method of making semi-conductor devices in multiple an impurity is diffused into a predetermined region or regions of a wafer of the opposite conductivity type and grooves etched in at least one face of the wafer so as to form isolated regions of said opposite conductivity type. The wafer is then subdivided into devices each containing at least one of these regions. In the embodiment PNPN switches are made by evaporating aluminium on to both faces of a 175� N type silicon wafer, etching to the form of two opposed grids, and diffusing it in to form a P type grid extending through the wafer. The entire surface of the wafer is next converted to P type by diffusing gallium through an oxide coating. Phosphorus is then deposited on and diffused into one face through apertures etched in the oxide coating to form N regions. Both faces are covered with oxide masking 12 (Fig. 8) and nickel electrodes 11 electroless plated on the exposed areas. After dipping in molten solder which adheres to the plating, a photo-resist mask is applied to leave only the grid region exposed. The overlying oxide and the wafer is then etched in this region down to the N type wafer material (Fig. 11). After applying a protective layer of silicone rubber the solder contacts are re-exposed by abrasion and the wafer divided along the grooves into individual elements. In an alternative method aluminium is diffused into only one face and the grooves formed in the other. To form a bi-directional switch additional N type regions are formed on the lower face of the wafer and beneath the site of the gate contact. |
