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Technique for Removing Metal Stripes From Processed Wafers

IP.com Disclosure Number: IPCOM000044540D
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Gajda, JJ: AUTHOR [+2]

Abstract

A process is described for removing metal stripes from processed wafers for analysis. In the process, the glass insulator beneath the stripe edges is removed by plasma etching. A collodion solution is applied to the surface and allowed to harden. The collodion is then peeled off, removing the metal stripe with it. During failure or contamination analysis, it is often desirable to remove metal stripes from processed wafers to analyze the stripes or underlying via structure. Wet chemical etching usually destroys the device characteristics or introduces spurious contaminants. The described procedure removes the stripes intact and introduces little or no contamination. The procedure, using Al or Al-Cu lands as an example, is as follows: 1. The glass layer is plasma etched using 90% CF4/10% O2 .

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Technique for Removing Metal Stripes From Processed Wafers

A process is described for removing metal stripes from processed wafers for analysis. In the process, the glass insulator beneath the stripe edges is removed by plasma etching. A collodion solution is applied to the surface and allowed to harden. The collodion is then peeled off, removing the metal stripe with it. During failure or contamination analysis, it is often desirable to remove metal stripes from processed wafers to analyze the stripes or underlying via structure. Wet chemical etching usually destroys the device characteristics or introduces spurious contaminants. The described procedure removes the stripes intact and introduces little or no contamination. The procedure, using Al or Al-Cu lands as an example, is as follows: 1. The glass layer is plasma etched using 90% CF4/10% O2 . Since the etching is isotropic, the metal lands will be undercut. The glass layer can be largely removed to give sufficient undercutting. 2. After baking the wafer on a hot plate and cooling, a 1% collodion (1% nitrocellulose in amylacetate) solution is flowed over the wafer, allowed to evaporate for 5 minutes and further dried in a stream of air or nitrogen for 5 minutes. This thin solution penetrates the undercut areas. 3. A 10% collodion solution is flowed over the wafer and dried at room temperature overnight at 50 C for two hours. The 10% solution builds up a thick layer for ease of removal. 4. Once dry, the collo...