VAPORIZATION

• Main Author: KAJITA MASAKI
• Format: Patent
• Language: English
• Published: 29.06.1989
• Subjects: BASIC ELECTRIC ELEMENTS; CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DIFFUSION TREATMENT OF METALLIC MATERIAL; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; METALLURGY; SEMICONDUCTOR DEVICES; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION

PURPOSE:To provide a uniform, favorable ohmic electrode, by vaporizing a very small quantity of Ag first so as to form nuclei for forming an electrode on a semiconductor wafer for preparing a light emitting diode and subsequently, vaporizing an Au-Zn alloy and further, Au. CONSTITUTION:After a desired degree of vacuum is obtained in a vacuum vessel, Ag 2 is heated by a heater 4 to vaporize Ag by a very small quantity that is enough to form nuclei of Ag on the surface of each wafer 7 to be deposited. After stopping heating of the heater 4, an Au-Zn material 3 is vaporized by heating with the heater 5. When the Au-Zn material 3 is heated, Zn having a high vapor pressure is preferentially deposited on the wafer 7. Flying Zn atoms or particles attach to surroundings of the nuclei and alloy Zn films in the form of islands to grow. With the progress of vaporization of Zn, the whole surface is covered with the Zn films 13. After that, Au is also vaporized and a deposited film 15 of Au-Zn alloy is formed. Au which is left till the end is vaporized and an Au film are formed on the surfaces.