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Browse Prior Art Database

Stitched Contact Structure for MOSFET

IP.com Disclosure Number: IPCOM000052701D
Original Publication Date: 1981-Jun-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Betz, PW: AUTHOR [+3]

Abstract

This metallization technique for MOSFET devices reduces the introductio of contaminants through metal to diffusion vias by using a plurality of small vias rather than a large continuous contact hole.

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Stitched Contact Structure for MOSFET

This metallization technique for MOSFET devices reduces the introductio of contaminants through metal to diffusion vias by using a plurality of small vias rather than a large continuous contact hole.

MOSFET devices can fail during use due to the migration of ionic contaminants into or near either thick or thin oxide gate regions. These contaminants alter the field created by the applied gate voltage and may artificially reduce the device threshold voltage to a point where the MOSFET cannot be turned off. Ionic contaminants, such as sodium, migrate to gate areas via the mechanism of field-assisted diffusion due to fields present from device wiring.

Contaminant diffusion barriers, such as silicon nitride and phosphosilicate glass, are commonly used to passivate devices to prevent such effects. Breaches in diffusion barriers between wiring metallization and the edges of the breach and associated processing circumvent the effectiveness of the barrier layer. These effects occur specifically around vias used to allow metallurgy to contact the semiconductor substrate. The larger the opening, the easier it is for contamination to migrate into areas of the device subject to applied fields. This problem may be alleviated by reducing the size of contacts, thus decreasing the effective edge length of each contact.

The figure illustrates an example of stitched contact structure applied to a typical metal gate MOSFET driver device. Source...