| 摘要 |
968,230. Semi-conductor devices. BROWN, BOVERI & CO. Ltd. Jan. 12, 1962 [Jan. 13, 1961], No. 1208/62. Heading H1K. A method of producing semi-conductor elements with PN junctions comprises forming a layer of opposite conductivity type on a body of semi-conductor material of the other conductivity type and then coating the body with a layer of nickel, an element then being cut out of the body perpendicularly to the nickel layer and the adjacent PN junction of one face and being ground so that the element is bevelled to reduce the area of the nickel coating and to expose the edge of the PN junction within the area of the bevel. As compared with customary Mesa constructions the invention increases the distance between the edge of the PN junction and the nickel coat which constitutes an electrode. As shown in Fig. 5, the body 1 of silicon has an impurity layer 2 formed by diffusion, the layer having been removed from the bottom surface and replaced by a doped layer 4 for the injection of majority carriers. The whole of body 1 is coated with nickel 5 which may be protected against subsequent etching by a gold topcoat. The body is then cut, by a cutting tool or by a tool with the use of a grinding medium, to have the shape shown in Fig. 6, the plan view corresponding to which is circular. On one side of the element the nickel coat is reduced in area to the disc 7 and at the midpoint of the bevel 6 the PN junction 8 is exposed. Gold, silver, or base metal leads may be connected to the nickel layers 7 and 5 on opposite sides of the element by means of a lead or lead alloy solder. The element may be etched to remove lattice defects due to grinding, but this is not necessary if the grinding medium is fine enough. If etching is employed it may be done before or after the attachment of leads and if employed in the latter case when the leads are of base metal, such as copper, they must be protected with a coat of gold, silver or lead, and the lead or lead alloy solder is chlorinated. The resulting element has a P+PN structure. |
