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Method to Control the Reliability of Ion Etched Vias

IP.com Disclosure Number: IPCOM000053101D
Original Publication Date: 1981-Aug-01
Included in the Prior Art Database: 2005-Feb-12
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Rathore, HS: AUTHOR

Abstract

The reliability of reactive ion etched (RIE) vias depends on the via slope and the amount of metal deposition along the slope. Up to now, the monitoring of this metal required the use of a scanning electron microscope (SEM). It is proposed to control RIE via reliability electrically by monitoring whether the via resistance lies within a predetermined tolerance range. A practical arrangement comprises, for instance, a 1200 via chain with a total resistance value of < or = 120 Omega to assure good reliability properties.

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Method to Control the Reliability of Ion Etched Vias

The reliability of reactive ion etched (RIE) vias depends on the via slope and the amount of metal deposition along the slope. Up to now, the monitoring of this metal required the use of a scanning electron microscope (SEM). It is proposed to control RIE via reliability electrically by monitoring whether the via resistance lies within a predetermined tolerance range. A practical arrangement comprises, for instance, a 1200 via chain with a total resistance value of < or = 120 Omega to assure good reliability properties.

The drawing illustrates a typical RIE via structure with Theta characterizing the critical via slope. Reliability is good if the slope is between 45 Degrees and 75 Degrees, and reliability is bad if the slope is between and 90 Degrees. This is due to the fact that during second metal deposition little or no metal is deposited on the slope when via slope is close to 90 Degrees. A comparatively thin metal coverage, in turn, results in a higher electrical via resistance than is the case with a thicker sidewall coverage. This effect is proposed to replace slope monitoring by SEM methods, required heretofore, which are not compatible with today's manufacturing line demands. Experiments showed that chains of 1200 vias with "good" side angle gave resistance values of 75 to 100 Omega per chain. The steep-sloped vias gave higher resistances. Reliability stress tests have shown that via chains of low resis...