Abstract

As integrated circuits’ geometry are reduced by about 0.7 for each new generation, failure analysis becomes more challenging in fault isolation and physical deprocessing to determine the root cause of the failure. It is impossible to deprocess the device by conventional wet-etch method as metallization tends to be etched or lifted off using all known wet chemicals. Currently the deprocessing techniques can be classified into two categories: dry-etch plus mechanical polishing and full dry-etched methods. In Chartered a new deprocessing technique by combining selective wet-etching of passivation and Inter Metal Dielectric (IMD) layers and mechanical lapping/polishing have been developed. Selective removal of passivation and IMD layers is of major importance in failure analysis of semiconductor devices. The key objective of this technique is to etch away passivation and IMD layers without attacking any metallization. This new deprocessing technique enables failure analyst to delayer by wet-etch again even those submicron devices. It avoided dry etch related problem such as selectivity, temperature control, etch rate stability, RIE grass, side wall polymer and end point detection…etc. It offers a cheaper alternative method for deprocessing when the plasma etcher is not available.

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