Chemistry: electrical and wave energy – Processes and products – Processes of treating materials by wave energy
Patent
1991-01-31
1991-12-31
Niebling, John
Chemistry: electrical and wave energy
Processes and products
Processes of treating materials by wave energy
204401, G01N 2726
Patent
active
050769065
ABSTRACT:
A procedure is disclosed for detecting and documenting flaws in the glassivation layer protecting the active device region of an integrated circuit. A droplet of dilute sulfuric acid solution is placed on top of the glassivation layer and a positively biased electrode is immersed in it. The leads coupled to circuit under the glassivation layer are coupled to a more negative voltage. The release of hydrogen bubbles into the solution through flaws in the glassivation via an electrolysis reaction are readily observable. Defects in a glassivation layer over nichrome devices may be documented by reversing the polarity of the bias to cause a reversal of the electrolysis process and a release of oxygen from the defective sites. This causes oxidation and disfigurement of the nichrome which can be documented using ordinary photographic means. Defects in a glassivation layer over aluminum may be documented by replacing the droplet of dilute sulfuric acid with a droplet of dilute sodium chloride; the resulting disfigurement may be photographed.
REFERENCES:
patent: 3408270 (1968-10-01), Gentile
patent: 3494837 (1966-10-01), Messner et al.
patent: 4514436 (1985-04-01), Moerschel
patent: 4919766 (1990-04-01), Kotowski et al.
patent: 4981567 (1991-01-01), Wolcott
Bell Bruce F.
Maginniss Christopher L.
Niebling John
Raytheon Company
Sharkansky Richard M.
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