| 摘要 |
PURPOSE:To contrive to reduce a component of the series resistance of the current-voltage characteristics of a buried Zener diode by a method wherein an auxiliary anode region having its raised impurity concentration is formed in the vicinity of the surface of the anode region. CONSTITUTION:An N<+> buried layer 102 and a P<+> buried layer 103 are formed on a P-type semiconductor substrate 101, and after that, an N<-> epitaxial layer 104 is formed. Then, an oxide film 105 is formed on the surface of the layer 104, diffusion windows 106 and 107 are provided on this film 105, a high-impurity concentration B ions are diffused through the windows 106 and 107, and an anode region 108 and an anode lead-out region 109, which reach up to the layer 103, are formed. Here for compensating the concentration of the B ions in the vicinity of the surface of the anode region 108, an auxiliary anode region 111 is formed in such a way as to position on the inner side of the region 108. Lastly, an N<+> cathode region 110 is formed in such a way as to cover the surface of the region 108. By this constitution, the breakdown voltage on the junction away from just under the window 106 can be approximated to that on the junction just under the window 106. As a result, the series resistance of this buried Zener diode can be dropped. |
