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Via Hole Etch End Point Detector

IP.com Disclosure Number: IPCOM000081631D
Original Publication Date: 1974-Jul-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Schwartz, GC: AUTHOR

Abstract

In fabricating multilevel interconnection metallurgy systems, the various levels are interconnected through via holes, i.e., an opening through an overlying passivating layer situated over a particular portion of the underlying interconnection metallurgy layer. It is essential that the via holes extend completely through the passivating layer, in order to make an operative complete metallurgy system. Detection of the completeness of the etching of the via hole is essential.

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Via Hole Etch End Point Detector

In fabricating multilevel interconnection metallurgy systems, the various levels are interconnected through via holes, i.e., an opening through an overlying passivating layer situated over a particular portion of the underlying interconnection metallurgy layer. It is essential that the via holes extend completely through the passivating layer, in order to make an operative complete metallurgy system. Detection of the completeness of the etching of the via hole is essential.

This method is applicable to determining the completeness of via hole etching when utilizing an aluminum or aluminum alloy metallurgy system. In order to test the completeness of the via etching process, a solution containing copper ions is applied to the overlying passivating layer. The solution can have the following composition: 1g CuSo(4).5H(2)O

50 ml glacial acetic acid

50 ml conc. H(3)PO(4).

With the solution at a temperature on the order of 40 degrees C, the wafer can be immersed for a time in The range of 20-30 seconds. If the via hole etchant opening is not complete and a layer of the insulator is present, no observable reaction will take place in the via openings. However, if the via etching is complete, the copper ions in the solution react with the underlying aluminum surface resulting in the deposition of a highly visible metallic copper layer. The presence of this layer is an indication that the etching is complete.

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