Simulation And Surface Characterisation Of Bondpad Pitting Corrosion In Wafer Fabrication
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Date
2003-04
Authors
Gan, Chong Leong
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Abstract
The Al bond pad undergoes galvanic corrosion in certain humidity level and halide
content environment. The objective of this study is to simulate and characterise the
bondpad pitting cOlTosion by varying the Al deposition grain size, pad etching and wet
cleaning conditions. It is important to tmderstand the optimum p.rocessing parameter
window a'}.d optimum bondpad profile. Several surface analytical techniques were
employed to identify the root causes such as SEM, EDX and high magnification optical
images. EDX results revealed that the improper wet cleaning, larger Al grain size and old
etching recipe unable to remove the trace fluorine content remain on AI bondpad surface
had caused bondpad pitting corrosion with native oxide as compared to nonnal Al
bondpad. SEM and optical images indicated that the bond pad with small pitting distributed
fairly on wafers were due to the present of fluOlife. The optimum bondpad formation
processing parameter's (lower AI grain size, new dry etch recipe and wet cleaning with
C02) will prevent the bondpad pitting corrosion III wafer tabrication,
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Keywords
To simulate and characterise the , bondpad pitting corrosion