Detection and Quantification of Surface Nanotopography-Induced Residual Stress Fields in Wafer-Bonded Silicon

Semiconductor wafer bonding has been identified as an enabling technology for a wide variety of semiconductor device processing applications such as wafer level encapsulation, three-dimensional structures and interconnects, and silicon-on-insulator substrates. In many of these applications accurate measurement and control of local residual stresses is critical for acceptable device yields and quality control. In this paper, synchrotron X-ray topography (XRT) and the infrared gray field polariscope (IR-GFP) are employed as full-field tools for the detection and measurement of residual stresses in wafer-bonded silicon. Both tools are used to inspect samples with varying levels of residual stresses from both wafer nanotopography and patterned interfacial features, resulting in excellent qualitative correlation between the tools. While the XRT offers higher spatial resolution and greater sensitivity to strain, the IR-GFP provides dramatically faster imaging rates, simple operating procedures, and instrument affordability. Based on these comparisons, the two techniques were shown to be complimentary tools for semiconductor processing control, the XRT being ideally suited as a laboratory research and development tool, while the IR-GFP is applicable for rapid process or quality control.