| 摘要 |
PURPOSE:To obtain a diode excellent in the noise characteristics and low in the operational resistance by providing a P<+> layer to be connected to a P<+> buried layer having an N epitaxial layer laid on a P layer with an N<+> buried layer while an N<+> layer is provided on an N epitaxial layer on the surface of the P<+> layer. CONSTITUTION:An N epitaxial layer 28 is made over an N<+> buried layer 27 provided on a P type substrate 26 and an N epitaxial layer 30 is made after a P<+> layer 29 is buried into the layer 28. When the epitaxial layers 29 and 30 are isolated by the P<+> layer, a P<+> layer 32 and an anode P<+> layer 33 are made to lead the anode electrode. Then, N<+> layer 34 is provided to attach electrodes 35 and 36 thereto. In operation, current flows vertically through a P-N junction 37 with a large sectional area hence not so big in the current density. Neither concentration of electric field nor heat generation occur on the surface of the substrate, meaning a high immunity to breakdown. As noise is reduced as generated at the center of re-connected section near the surface while the buried layers 29 and 27 are kept out of contact, there is no increase in the resistance of the P<+> buried layer 29 thereby minimizing the operational resistance. Thus, a Zener diode with a higher withstand voltage is obtained without additional process. |
