Browse Prior Art Database

Low Reverse Leakage Schottky Barrier Diode

IP.com Disclosure Number: IPCOM000085209D
Original Publication Date: 1976-Mar-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 68K

Publishing Venue

IBM

Related People

Battista, MA: AUTHOR [+3]

Abstract

During the fabrication of nitride defined Schottky barrier diodes (SBD), two masking steps are used to complete the anode contact opening. The first step etches silicon nitride (Si(3)N(4)) and the second etches silicon dioxide (SiO(2)). Certain edge problems result from this method because the SiO(2) undercuts the Si(3)N(4) layer as shown in Fig. 1. As a result, the etched Pole becomes difficult to clean leaving the surface susceptible to electrical surface problems, resulting in poor diode forward and reverse characteristics. This is particularly a problem for large memory arrays where many diodes are used in parallel and low-standby current is desired.

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Low Reverse Leakage Schottky Barrier Diode

During the fabrication of nitride defined Schottky barrier diodes (SBD), two masking steps are used to complete the anode contact opening. The first step etches silicon nitride (Si(3)N(4)) and the second etches silicon dioxide (SiO(2)). Certain edge problems result from this method because the SiO(2) undercuts the Si(3)N(4) layer as shown in Fig. 1. As a result, the etched Pole becomes difficult to clean leaving the surface susceptible to electrical surface problems, resulting in poor diode forward and reverse characteristics. This is particularly a problem for large memory arrays where many diodes are used in parallel and low-standby current is desired.

The improved SBD described here uses the same two masking steps, however, the Si(3)N(4) layer is cut back away from the contact area leaving the SiO(2) to define the contact hole opening. The topographic and cross-sectional views are shown in Fig. 2.

With the gradual reduction of passivation layers, any contamination remaining during photoresist is easily cleared away from the contact opening. This cleaner surface will result in improved device characteristics and better reliability. In addition, when the device is reverse biased, the electric field around the edge of the anode contact will reflect an opposite charge in the silicon, forming a built-in guard ring. This guard ring will reduce the reverse leakage of the SBD, (Fig. 3).

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