| 摘要 |
1,163,240. Semi-conductor devices. WESTINGHOUSE ELECTRIC CORP. 19 April, 1968 [25 April, 1967], No. 18533/68. Heading H1K. A three-region semi-conductor device comprises an N-type substrate 10 with N-type, P- type and N-type layers 16, 18, 22, respectively, deposited epitaxially thereon while the substrate is maintained at a constant elevated temperature. Gaseous etching of the substrate 10 prior to deposition of the first layer 16 is also carried out at the same temperature. For the Si transistor shown the preferred temperature is 1000-1200� C., HCl gas being used as the gaseous etchant. The layers 16, 18, 22 are deposited from a mixture of H 2 , a silicon halide such as SiCl 4 and a suitable dopant source such as arsine, phosphine or diborane. Between successive stages the chamber containing the substrate is flushed with dry H 2 . Preferred thicknesses and resistivities are specified for the substrate 10 and for the layers 16, 18, 22. An aperture is etched through the upper layer 22 to beyond the first junction 24 using an oxide mask. The aperture may have a complex peripheral outline to provide a long emitter-base junction edge. A collector electrode 34 of Mo, W or Ta is soldered to the substrate 10 using an Ag/Pb/Sb solder, and Al emitter and base electrodes 36, 38 are evaporated on to the layers 22, 18, respectively, and are alloyed thereto. A protective coating 40 is provided over the exposed junction edges, which are first prepared by sandblasting, etching and polishing. Alternative semi-conductor materials are SiC, Ge and III-V or II-VI compounds. |
