| 摘要 |
PURPOSE:To obtain the photo trigger thyristor having the required photo trigger by a method wherein a thickly formed NE layer is thinned off by performing an etching. CONSTITUTION:The NE layer of light-receiving part is formed simultaneoulsy with the NE layer of an ordinary thyristor under the same condition. In regard to the distribution diagram for impurity density, the abscissa (x) indicates the depth from the wafer surface, (a) region indicates NE layer 4, and (b) region indicates PE layer 3. The ordinate (y) indicates the impurity density in logarithmic scale. After the diffusion as indicated in the diagram has been performed, the light-irradiated part 8 on the NE layer is thinned off by performing an etching. As indicated in the diagram, the impurity density of the NE layer 4 on the light-irradiated part 8, which is left by etching, is reduced and the sheet resistance PS is increased. Accordingly, the NE layer suitable for the phot trigger thyristor can be formed by properly controlling the amount of etching. As the thickness of the NE layer on the light-receiving part is formed in 5-10mum in thickness without having a special process and the sheet resistance is set at 50OMEGA or above, an excellent photo trigger characteristics can be obtained. |
