JPS641284A - Zener diode - Google Patents

Abstract

PURPOSE: To suppress change of characteristic of yield voltage for stabilization by covering the entire part or greater part of the terminating region in the side of surface insulation layer of pn junction in which the yield of junction may occur with an electrode connected to the p type region side.

CONSTITUTION: An n-type layer 1 is formed on a substrate and a p⁺ type region 2 is formed to an n-type layer 1 by impurity diffusion. The n⁺ type region 3 is formed to such p⁺ region 2 and a depletion layer is formed by the carrier diffusion between both regions in the vicinity of the pn junction of the p⁺ type region 2 and the n⁺ type region 3. In the succeeding processes, the electrode 5 connected to the p⁺ type region 2 is formed in such a shape as covering the pn junction J of p⁺ type region 2 and n⁺ type region 3 from the above area of insulating film 4. When a backward bias voltage is applied across the p⁺ type region 2 and n⁺ type region 3 through the electrodes 5, 6, the yield phenomenon occurs at the pn junction J in the vicinity of insulating layer 4 and the device operates as a zener diode. In this case, the hoe electrons cannot easily be implanted to the insulating film 4 because the electrode 5 in the p⁺ type region side to which the negative bias is applied covers the pn junction J from the above area of the insulating layer 4, change of shape of depletion layer is suppressed and change with time of yield voltage can be alleviated.

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