| 摘要 |
<PICT:1090649/C1/1> A glassy insulating covering is provided on a semi-conductor body by providing on its surface, a layer consisting only of an oxide of lead, heating sufficiently to cause reaction between the lead oxide and another oxide to form a glass covering, the temperature being insufficient to effect any rediffusion of impurities in the semi-conductor body. In one example a mesa type body comprising a PN junction formed by diffusing boron into an N-type silicon body is provided with a film 6,000 </>rA thick of silicon dioxide by pyrolytic decomposition of tetraethoxysilane and then a 1,000 </>rA layer of PbO is provided by evaporation. The element is heated for 15 minutes at 650 DEG C. to provide a glass film consisting of SiO2 and PbO, the lower part of the original silicon oxide layer remaining unchanged. The diode is completed by removing part of the film with acidic ammonium fluoride and depositing gold or aluminium to form one electrode, the other electrode being provided by nickel plating the base portion; in a further example, all the silicon described film is reacted with the lead oxide to form the glass layer. In another example lead oxide, without any previous layer of silicon oxide, is provided on the surface of a silicon body and during heat treatment in an oxidizing atmosphere, the silicon under the lead oxide is oxidized so that glass is again formed by reaction between the lead oxide and the silicon oxide; such oxidation provides an etching effect on the silicon and may remove undesired impurities. In a further example, lead is provided as a thin coating which is oxidized in a first oxidizing process and a second heating treatment is carried out to form the glass coating. Germanium or compound semi-conductor may be used in place of silicon. |
