| 摘要 |
PURPOSE:To obtain the titled device of low ON-voltage and high effect of carrier suck-out by a method wherein an N-cathode layer is formed by phosphorus diffusion from one surface of the semiconductor substrate having PNP three layers, and a layer containing phosphorus in almost the same amount as that of the N-cathode layer is then formed on the surface of a P-anode layer; thereafter, Au diffusion is carried out. CONSTITUTION:After phosphorus diffusion to form the cathode layer, a phosphorus layer of low concentration is formed on the anode side. In other words, in a high vacuum, a thyristor wafer is turned to the anode side and placed on the electrode kept at a temperature of 200-300 deg.C, and voltage is impressed between the electrode opposed above the anode side. On Ar gas supply here, phosphorus decomposed by plasma effect mounts on the wafer, and phosphorus atoms penetrate into the wafer and deposit on the wafer surface. When the thyristor wafer is then subjected to Au diffusion e.g. at 870 deg.C for 90min, an Au distribution of less gradient than by the conventional method can be obtained. After Au diffusion, a required region of the N-cathode layer 24 is removed by selective etching, and the electrode is attached. |
