An abnormal capacitance case of capacitive accelerometer after inductive coupled plasma (ICP) release was investigated to solve the failure problem. scanning electron microscopy (SEM)/transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDX), X-Ray transmission inspection, epoxy resin filling/polishing were used to identify the possible root cause. Failure analysis results confirmed that abnormal capacitance occurred by some connecting combs. Based on the results of three ways to analysis, it was concluded that the abnormal capacitance was not due to the contamination between combs of accelerometer and the substrate, but due to the connection between some combs caused by the ICP etching ununiformity. The static capacitance and resistance test results also testified this conclusion.

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