| 摘要 |
A method of producing a coating on a semi-conductor body or on a metal electrode for use in a semi-conductor device comprises the steps of immersing the body or electrode first in an alkaline solution of a gold compound to produce a deposit of gold thereon and secondly in an acid solution of a compound of antimony, arsenic or bismuth while contacting the body or electrode with a metal which will displace the Sb, As or Bi from the solution on to the gold, and then removing from the solution and heating to diffuse the Sb, As or Bi into the gold. In one embodiment a wafer of N type silicon prepared by etching in a mixture of concentrated nitric and hydrofluoric acids, followed by lapping, is immersed in a solution comprising potassium gold cyanide, potassium hydroxide and water which is heated at a rate of 2 DEG C./minute to 70-80 DEG C. and maintained at that temperature for from 20-80 minutes. The resulting gold plated wafer is degreased and then immersed in a warm solution comprising antimony trichloride, hydrochloric acid, water, and a commercial wetting agent with the gold in contact with a metal such as copper, nickel, brass or aluminium, to produce a thin deposit of antimony on the gold. After successive rinses in hydrochloric acid, water and acetone, and drying, the plated wafer is heated first to 400-450 DEG C. for 15 minutes in nitrogen to diffuse the antimony into the gold and then for 5 minutes at 700-900 DEG C. to alloy the doped gold to the wafer to form a low resistance contact therewith. An external lead may then be soldered to the gold. In another embodiment an aluminium strip is plated by the above mentioned processes and after the heating to diffuse the antimony into the gold is heated in contact with a body of N type semi-conductor to form an alloyed ohmic contact therewith. Specifications 706,849 and 769,673 are referred to. |
