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This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.
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Table 2430. Bond-pad contamination in IC devices induced during wafer packaging and shipping.
Contaminant |
Contamination sources |
Effects |
Fluorine |
Introduced through top metal etch or pad opening process, wafer packaging foam material, or shipping |
Induce non-sticking bond pad
|
Fluorine can
react with Al to form F crystal: (NH4)3(AlF6) compound [1]; High fluorine contamination can induce thick native
oxide |
Oxygen |
Introduced during backside grinding process or pad opening process (e.g. formed AlxFyOz), by reactive epoxy diluents, or by package paper during shipping (e.g. containing Al, F, O, and K) [e.g. Figure 2430] |
|
Kalium |
Introduced by package paper during shipping |
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Figure 2430 shows an example of C, O, and Si contaminated bond pads. Area S6 had an abnormal film on the native Al oxide, while area S5 presented nonhomogeneous, loose and empty SixAlyCzOm materials in the hemispherical defect. These pad defects existed only at wafer edge because backside grinding was the root cause of the contamination.
Figure 2430. Contaminated bond pads. Adapted from [2]
[1] Y. N. Hua, S. Redkar, C. K. Lau, “A Study on Non-
Stick Aluminium Bondpads due to Fluorine
Contamination using SEM, EDX, TEM, IC, Auger, XPS
and TOF-SIMS Techniques,” Proceedings from the 28th
International Symposium for Testing and Failure
Analysis, Phoenix, Arizona, November, 2002, pp. 495-504.
[2] Paul Yu, Jamie Su, Qiang Gao, Ming Li, Chorng Niou, Study of Aluminum Pad Contamination Sources during Wafer Fabrication, Shipping, Storage and Assembly, International Symposium on High Density packaging and Microsystem Integration, 2007. HDP '07.
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