Browse Prior Art Database

Evaporation Shielding for Continuous Pb in Deposition

IP.com Disclosure Number: IPCOM000087071D
Original Publication Date: 1976-Dec-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 3 page(s) / 112K

Publishing Venue

IBM

Related People

Brunner, RH: AUTHOR

Abstract

Indium (In) and lead (Pb) composition pad metallurgy is applied to the wafer using a moly mask in a vacuum metallizer. The metals are applied in a two-step process: In first and Pb second. Reflow occurs after mask removal in adjacent subsectors.

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Evaporation Shielding for Continuous Pb in Deposition

Indium (In) and lead (Pb) composition pad metallurgy is applied to the wafer using a moly mask in a vacuum metallizer. The metals are applied in a two-step process: In first and Pb second. Reflow occurs after mask removal in adjacent subsectors.

Described is a method for applying the two-layer metallurgy by evaporating the two metals in separate crucibles, which provides pure metal to the wafer. Mobile vapors, which impinge on the heatable inverted funnel, can be successively remelted and returned to the original crucible.

Fig. 1 shows a wafer and mask assembly 4 mounted on a cooled, retractable plate 6 in a deposition position, which allows the source chamber 8 to be isolated by activating the gate valve 10 after completing a deposition. This retracting mechanism, in its extended position, also seals the mask and funnel, which minimizes stray evaporant from coating the upper chamber surfaces.

Each metal is in a separate evaporation source (In in 12 and Pb in 14). After each metal is evaporated (Fig. 2), the funnel shield 20 is heated by the sealed heating elements 1A. The excess evaporated metal then flows back to the evaporation source through the funnel trough 22. The funnel trough is positioned by the trough-positioning mechanism 24.

Another way to totally eliminate the possibility of losing composition control or causing source cross-contamination is to dedicate source funnels (Fig. 3). Each funnel captur...