WAFER TYPE MILLIMETER WAVE RECTIFIERS 



1387 



?^^^^^^^^ 



"ARALDITE" 



BONDING 



RESIN 



WELD 



0.014" SILICON 



SQUARES 

 0.0065" THICK 



0.0009" DIA 

 TUNGSTEN 

 WIRE 



WAVEGUIDE 



Fig. 2 — Millimeter-wave point-contact assembly. 



The region of the wafer unit containing the silicon and point contact is 

 shown in Fig. 2. The methods used in preparing the silicon wafer and 

 the spring contact point are similar in many respects to the standard 

 techniques used in the manufacture of rectifiers for longer wavelengths. 

 Some modifications and refinements in technique are called for by a 

 decrease in size and the increased frequency of operation. 



A single-crystal ingot, grown from high purity DuPont silicon doped 

 with 0.02 per cent boron, furnishes the material for the silicon squares 

 used in the wafer unit. Slices cut from the ingot are polished and heat 

 treated. Gold is evaporated on the back surface and the slices are diced 

 into squares approximately 0.014-inch square and 0.0065-inch thick. 

 These squares are pressed into indentations formed in the ends of the 

 0.030-inch copper pins which have previously been tin-plated. The rods 

 are then cemented in place in the wafer. The spring contact points are 

 made of pure tungsten wire that has been sized to 0.9 mil in diameter by 

 an electrolytic etching process. A short length of this wire is spot welded 

 on the conical end of the 0.031 -inch nickel rod. The wire is then bent into 



