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Etch Test to Show Pits under Copper Decorated Areas

IP.com Disclosure Number: IPCOM000076995D
Original Publication Date: 1972-May-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Couture, RA: AUTHOR

Abstract

An electroplating copper decoration test followed by a hydrofluoric acid etch will produce pits in silicon underlying a silicon dioxide surface, in regions where defects in the SiO(2) surface provide a conductive path to the silicon surface for the copper decoration. The electroplating test fills the conductive paths through the SiO(2) to the silicon surface with copper. The copper is then removed by use of nitric acid. The test specimen is now subjected to a hydrofluoric acid buffered with ammonium fluoride etch solution that will remove SiO(2). While the etching is carried out, a DC current is applied across the solution and the silicon underlying the SiO(2). When current flows the test is stopped and the remaining thickness of SiO(2) determined. This is known as the pinhole break up thickness.

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Etch Test to Show Pits under Copper Decorated Areas

An electroplating copper decoration test followed by a hydrofluoric acid etch will produce pits in silicon underlying a silicon dioxide surface, in regions where defects in the SiO(2) surface provide a conductive path to the silicon surface for the copper decoration. The electroplating test fills the conductive paths through the SiO(2) to the silicon surface with copper. The copper is then removed by use of nitric acid. The test specimen is now subjected to a hydrofluoric acid buffered with ammonium fluoride etch solution that will remove SiO(2). While the etching is carried out, a DC current is applied across the solution and the silicon underlying the SiO(2). When current flows the test is stopped and the remaining thickness of SiO(2) determined. This is known as the pinhole break up thickness. The areas of the SiO(2) which showed copper decoration now show pits in the form of circles for <100> oriented silicon. If the pinhole break up thickness test alone is carried out, no such pits are observed.

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