| 摘要 |
797,687. Semi-conductor devices. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. May 28, 1956 [July 28, 1955], No. 21831/55. Drawings to Specification. Class 37. A method of making a PN junction rectifier comprises the following steps: placing a pellet of activator material characteristic of one conductivity type on a semi-conductor wafer of the opposite type, heating in vacuo or in an inert atmosphere to a temperature slightly above the melting-point and wetting temperature of the activator, forming an oxide skin on the activator, raising the temperature to the optimum temperature for alloying, and then cooling. In the embodiment an indium pellet is placed on a germanium wafer mounted on a nickel baseplate, and heated in a flow of oxygen-free hydrogen to 300 ‹ C. The flow of hydrogen is then replaced by a flow of nitrogen containing some oxygen and the assembly raised to the optimum alloying temperature of 510‹ C. The assembly is then cooled and, if desired, the oxide layer is removed from the indium by etching. The effect of the oxide film is to raise the surface tension so that the uncontrolled spread of indium over the germanium surface which would otherwise occur at the optimum alloying temperature is avoided. Sufficient oxygen may be introduced into the nitrogen by bubbling it through water. The method may also be used in alloying an antimony pellet to a wafer of silicon. |
