| 摘要 |
1,009,811. Semi-conductor devices. WESTINGHOUSE ELECTRIC CORPORATION. Dec. 31, 1963, No. 51284/63. Heading H1K. An ohmic contact is made to a diffused layer of one conductivity type in a region of the opposite conductivity type by depositing an epitaxial layer on the diffused layer and fusing an ohmic contact to the epitaxial layer. As shown, Fig. 7, an NPNP switching device is manufactured by diffusing indium, gallium, aluminium, or boron into the surface of a circular N-type silicon wafer to produce P-type surface regions 17, 18. The top surface of the wafer is oxidized and a photolithographic technique is used to produce a mask through which antimony, arsenic, or phosphorus is diffused to produce the annular emitter region 28. The remaining oxide layer is removed and an epitaxial layer 36 of degenerate N-type silicon is deposited over the entire top surface of the wafer by decomposition of silicon tetrachloride and a chloride or other halide of the doping material carried in a hydrogen stream. The sides of the emitter region are then isolated from the surrounding regions by etching annular grooves 40, 42. The epitazial layer and part of the surface of the gate region 17 are also removed by etching and ohmic contacts are produced by alloying a foil 48 of gold containing antimony, arsenic or phosphorus to the epitazial layer convering the emitter region, and alloying foils 52, 54 of gold containing boron, aluminium, gallium or indium to the exposed surface 43 of region 17 and to the underside of the wafer respectively. In a second embodiment, Fig. 10, the diffused regions 17, 18, and 28 are produced as in the first embodiment, an oxide layer 60 is formed over the entire surface of the wafer, an annular window is etched in the layer to expose the emitter region 28 and a degenerate N-type silicon epitaxial layer 62 is deposited on top of the oxide layer so that it makes contact with the emitter region 28 through the window. A window is etched in the epitaxial and oxide layers 62, 60 to expose the gate region within the emitter ring, and the oxide layer is also removed from the lower face of the wafer. Ohmic contacts 64, 68, 70 are made to the emitter, gate, and collector electrodes by alloying doped gold foils to the wafer. The original wafer may be a slice of single crystal or dendritic crystal material. Specifications 889,058 and 913,674 are referred to. |
