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Technique for Observing Defects at the Metal Silicide-Silicon Interface in a Schottky Barrier Diode

IP.com Disclosure Number: IPCOM000047052D
Original Publication Date: 1983-Sep-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Blake, HH: AUTHOR [+3]

Abstract

This is a technique for precisely identifying a defect region in a Schottky barrier diode. Significant yield loss occurs in the manufacture of bipolar arrays utilizing Schottky diodes in single cells. The Schottky diodes are processed with a metal layer having a known barrier height for proper cell switching. However, if the barrier layer used to prevent metallurgical reaction between an Al, Al-Cu and/or Al-Cu-Si conductor metal and silicide, such as PtSi, Pd2Si and Ni2Si, makes contact to the Si anode, the cell becomes inoperative (Fig. 1). The technique outlined here successfully identifies the exact regions of contact causing the high series resistance. Inoperative Schottky diodes are initially identified by measuring the I-V characteristic.

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Technique for Observing Defects at the Metal Silicide-Silicon Interface in a Schottky Barrier Diode

This is a technique for precisely identifying a defect region in a Schottky barrier diode. Significant yield loss occurs in the manufacture of bipolar arrays utilizing Schottky diodes in single cells. The Schottky diodes are processed with a metal layer having a known barrier height for proper cell switching. However, if the barrier layer used to prevent metallurgical reaction between an Al, Al-Cu and/or Al-Cu-Si conductor metal and silicide, such as PtSi, Pd2Si and Ni2Si, makes contact to the Si anode, the cell becomes inoperative (Fig. 1). The technique outlined here successfully identifies the exact regions of contact causing the high series resistance. Inoperative Schottky diodes are initially identified by measuring the I-V characteristic. In the new procedure both the second metal and the interlay glass are first removed by mechanical polishing. The conductor metal is removed by preferential etching of the Al-Cu, leaving the Cr barrier layer and PtSi intact.

Metallurgical polishing with the conductor metal and glass present causes considerable rounding off of the sections, and the Cr-PtSi interface can not be resolved. After the conductor metal is removed, a sputtered glass layer is deposited over the exposed Si surface. Therefore, the relative hardness between the Cr and PtSi is the same. This procedure puts every layer in the exact same plane after polishin...