| 摘要 |
899,063. Semi-conductor devices. MULLARD Ltd. July 29, 1958, No. 24404/58. Class 37. An electrical connection to each of a pair of projections on a semi-conductor mass is made by providing electrical connection between the two projections and a common conductor extending between them and beyond them in each direction and thereafter severing the conductor between the two projections. In Fig. 1, a pellet of bismuth containing 1% arsenic is lightly alloyed to one side of a slice of P-type germanium crystal by heating to about 650‹ C. in hydrogen. A slot 12 is cut across the resolidified layer of bismuth by ultrasonic cutting means, dividing it into two projecting parts 5, 6, and the assembly is etched in hydrogen peroxide. Aluminium is then deposited on the surface of the right-hand part 6 of the-divided resolidified layer and the device is again heated in hydrogen to about 750‹ C. The other surface of the crystal slice is then etched, a collector of indium containing 1 % gallium is alloyed to it by heating it to 500‹ C. in hydrogen and a stout nickel wire 9 is soldered to the resolidified indium 7, using an indium solder 10. A strip of silver 11 .is then brought into contact with the parts 5 and 6 and the device is heated to about 330‹ C. in hydrogen, thus alloying the strip to the parts 5 and 6, between which the silver strip is then severed. With the channel 12 protected by a drop of polystyrene lacquer, the device is electrolytically etched in an aqueous solution of sodium hydroxide, during which process the N-type layer 8 is removed. The transistor is then etched in hydrogen peroxide, washed, dried and encapsulated in any known manner. Fig. 1 shows the unchanged P-type region of the crystal 1, an N-type layer 2 due to the arsenic and bismuth, a P-type layer 3 due to the aluminium, an N-type layer 8 due to the fact that arsenic diffuses more rapidly than aluminium, a P-type alloy layer 4 in the crystal slice, and the two parts 5 and 6 of bismuth and arsenic and, in the one case, aluminium also. As a modification, an indifferent material such as lead may be alloyed originally to the crystal slice, a narrow channel provided in the resolidified material, an acceptor impurity added at one side of the channel and a donor impurity at the other side and alloying heat applied to provide the junctions. Fig. 3 shows another embodiment in which a slice of N-type germanium has two P-type zones 13 and 14 produced by alloying pellets of indium to the surface. The upper surface, including the projections 15 and 16, is then covered with a layer of polystyrene lacquer which is removed from the upper parts of the projections either by mechanical or chemical means. A layer of silver 18 is then applied, as by evaporation in vacuo, and is thereafter severed at 19 by ultrasonic cutting means. Specification 856,430 is referred to. |
