Trapped particle detection in bonded semiconductors using gray-field photoelastic imaging

In this paper we present inspection results from several bonded wafer systems using a newly developed infrared gray-field polariscope (IR-GFP). This device measures the residual stress-fields associated with defects trapped at the bonded interface to enable the detection of subwavelength defects. Results from IR-GFP imaging are contrasted with conventional infrared transmission (IRT) imaging of the same samples, showing marked improvements in defect detection as well as the ability to quantify the residual stress fields. This inspection method reveals that interfaces deemed defect-free using IRT imaging may be, in fact, teeming with defects.