| 摘要 |
1,130,511. Semi-conductor devices. RADIO CORPORATION OF AMERICA. 22 Nov., 1965 [7 Dec., 1964], No. 49589/65. Heading H1K. The minority carrier lifetime in a silicon or silicon-germanium body is decreased without unduly increasing the resistivity by first coating one face with nickel, cobalt or nickel-cobalt alloy and heating to diffuse in the coating material, removing any residue, and then coating with gold and heating to diffuse the gold through the nickel or cobalt diffused region. In one embodiment a controlled rectifier is made by first forming N-type regions at the opposite surfaces of a high-restivity P-type silicon wafer by epitaxial deposition or impurity diffusion. An annular region of P-type is then formed in the surface of one of the layers by diffusion of boron from the vapour phase through oxide masking formed by conventional methods. After removing the masking both faces of the wafer are coated with nickel, cobalt or alloys thereof and this is then diffused in by heating in a non- oxidizing ambient. Surface residues of the metals are next removed by treatment with a boiling solution of a metal chloride in hydrochloric acid and the face not diffused with boron coated with gold by evaporation. This is diffused throughout the entire wafer by heating at 860-900� C. in a non-oxidizing atmosphere and then cooling slowly. Nickel electrodes are then plated on the annular P zone and the N-type regions. In an otherwise similar embodiment the starting wafer is of a silicon rich germaniumsilicon alloy and the N regions are formed by diffusion of arsenic or phosphorus. A device with reversed zone conductivity types can be similarly formed from an N-type silicon wafer using boron and phosphorus respectively in the first and second diffusion steps. |
