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    Switching transistor
    16.
    发明授权
    Switching transistor 失效
    开关晶体管

    公开(公告)号：US2968751A

    公开(公告)日：1961-01-17

    申请号：US67729557

    申请日：1957-08-09

    Applicant: RCA CORP

    Inventor： MUELLER CHARLES W ,  BARTON LOY E

    IPC: H01L21/00 ,  H01L21/033 ,  H01L21/225 ,  H01L29/00 ,  H03K3/02 ,  H03K3/35

    CPC classification number: H03K3/35 ,  H01L21/00 ,  H01L21/033 ,  H01L21/225 ,  H01L29/00 ,  H03K3/02

    Abstract: 864,705. Semi-conductor devices. WESTERN ELECTRIC CO. Inc. Aug. 8, 1958 [Aug. 15, 1957], No. 25502/58. Class 37. A semi-conductor device having regions of differing conductivity produced by vapoursolid diffusion of significant impurities is made by a method comprising the forming of an oxide layer of a face of a silicon body, producing an etchresistant pattern on the face, applying an etchant to remove the oxide layer to expose the silicon in accordance with the pattern, removing the etchresistant pattern and subjecting the face to . the vapour of a significant impurity not capable of penetrating the oxide layer. According to one example, a P-type layer formed on a single crystal of N-type silicon by heating in an atmosphere of boron was removed from all the surfaces except one major face. The cleaned wafer was then oxidized by heating in a tubetype furnace, cleaned with toluene and, after drying, covered with photo-resist (compounded of polyvinyl cinnamate, methyl glycol acetate and perinaphthenone sensitizer compound). The pattern shown in Fig. 4A was then produced by photographic techniques. After the resist had hardened the oxide beneath the exposed portions of the pattern was etched away using a solution of ammonium bifluoride after which all the remaining photo resist was washed of using a suitable solvent. The wafer was then subject once more to diffusion in a boron atmosphere thus producing P-type conductivity regions of the exposed quadrants of the upper face of the crystals. The wafer was then oxidized again and the same process was used to produce the pattern shown in Fig. 7A in the oxide layer the crystal was then subject to diffusion treatment in a phosphorus pentoxide atmosphere to produce N-type conductivity regions. After washing the device was subject to final processing including the attachment of electrodes. The same method may be used for etching away exposed parts of a silicon crystal as well as the oxide layer described above and in this case a suitable etchant is silver nitrate solution in nitric and hydrofluoric acid. Specifications 717,708, 717,710, 717,712, 805,207 and 809,644 are referred to.

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