Browse Prior Art Database

Contact Penetration Prevention

IP.com Disclosure Number: IPCOM000062777D
Original Publication Date: 1986-Dec-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Chicotka, RJ: AUTHOR [+4]

Abstract

Process procedures current in the production of silicon wafer devices invoice the controlled chemical deposition and removal of various metallic films and insulating layers under vacuum. A process is here disclosed by which a thin silicon dioxide (Si02) layer is formed on a PtSi surface prior to, and immediately following, the deposition of chromium (Cr). The PtSi surface is thereby rendered impervious to possible aluminum (Al) contact penetration (diffusion) of the Cr barrier layer protecting it, with improvement in reliability and product yield.

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Contact Penetration Prevention

Process procedures current in the production of silicon wafer devices invoice the controlled chemical deposition and removal of various metallic films and insulating layers under vacuum. A process is here disclosed by which a thin silicon dioxide (Si02) layer is formed on a PtSi surface prior to, and immediately following, the deposition of chromium (Cr). The PtSi surface is thereby rendered impervious to possible aluminum (Al) contact penetration (diffusion) of the Cr barrier layer protecting it, with improvement in reliability and product yield.

Aluminum penetration at the periphery of (and through gaps in) a chrome barrier layer covering semiconductor device contacts on a wafer, leads to the conversion of PtSi to PtAl2, and results in device degradation due to emitter-base leakage, or shorting, and erratic SBD (Schottky Barrier Diode) forward voltage.

The disclosed process involves reforming a slight Si02 layer, by one of several methods, after BHF etch and prior to Chrome metal evaporation. Following chrome deposition, this oxide layer step is repeated. A thicker oxide is thus formed at the exposed periphery of the PtSi layer and greater passivation in that region is assured without incurring changes in the contact resistance of the main body of the device. The resulting Si02 layer also acts to prevent Si from the bulk contact from diffusing to the Cr and forming CrSi2, etc.

The formation of Si02 can be accomplished with either...