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Inherent Multi-sloped Contact for Void Free Surface Tungsten Contact utilizing Stud Technologies

IP.com Disclosure Number: IPCOM000109173D
Original Publication Date: 1992-Aug-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Dang, D: AUTHOR [+4]

Abstract

A technique is described that yields a void-free surface on tungsten contact studs on semiconductor wafers. Tungsten studs are subject to the formation of voids if the studs pass through a PSG insulator that has a vertical profile. See Fig. 1. Etchback leaves exposed voids that are difficult to fill. Fig. 2 shows a composite insulator of SiO2 over PSG that provides a vertical profile in the PSG, but a slightly beveled profile in the SiO2. The bevel forces any voids to form deeper in the stud so that etchback does not expose the voids. The void-free tungsten stud surface allows the use of either sputtered or evaporated contact metallurgies. The bottom of the contact hole remains vertical so that no additional lateral leakage mechanisms are incurred.

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Inherent Multi-sloped Contact for Void Free Surface Tungsten Contact utilizing Stud Technologies

       A technique is described that yields a void-free surface
on tungsten contact studs on semiconductor wafers. Tungsten studs are
subject to the formation of voids if the studs pass through a PSG
insulator that has a vertical profile.  See Fig. 1. Etchback leaves
exposed voids that are difficult to fill.  Fig. 2 shows a composite
insulator of SiO2 over PSG that provides a vertical profile in the
PSG, but a slightly beveled profile in the SiO2.  The bevel forces
any voids to form deeper in the stud so that etchback does not expose
the voids.  The void-free tungsten stud surface allows the use of
either sputtered or evaporated contact metallurgies.  The bottom of
the contact hole remains vertical so that no additional lateral
leakage mechanisms are incurred.  The bevel increases the
metal/tungsten overlap area so that resistance to electromigration is
improved.