Semiconductor devices

Claim 1

In a method of producing a semiconductor device in the form of an IMPATT diode, the steps of: selecting a slice of semiconductor material having an epitaxial layer on an n + substrate material; diffusing a p + layer into the epitaxial layer to form an abrupt p + -n junction; removing the uppermost 80 to 120A of the diffused p + layer by RF sputter etching under plasma conditions thereby inhibiting change in surface crystal structure; thinning the n + substrate material to a desired thickness for the device; producing a photolithographic mask on the surface of the n + substrate material; depositing by sputtering, on both the p + and n + surfaces a succession of layers of titanium, 800-1200A, platinum 1,600-2,400A, and gold, 8000-12,000A, and electroplating gold layers over these sputtered gold layers; removing the photolithographic mask to expose the surface of the n + substrate material around a series of gold pads; by high energy proton bombardment, passivating the zones of semiconductor material in depth through the slice to create zones of semi-insulating material to isolate the semiconductor material directly below the gold pads, the energy of protons being increased in stages at intervals of less than 0.11MeV up to an energy in MeV approximately equal to one-tenth of the required passivated layer thickness in μm using a proton dose at each stage of from 10 14 to 5 × 10 15 cm -2 and a rate of from 2 × 10 12 sec -1 to 5 × 10 12 sec -1 using a proton scan raster pattern ensuring uniformity of dose over the area of the device; and mounting the processed semiconductor material on to a heat sink and connecting one or more of said gold pads to a connection block.