Device Failure Analysis with Epi-Si Wafer Using Raman Shift Matching Method

Abstract

In this study, a multi-wavelengths Raman spectroscopy method was employed to evaluate the quality of epitaxial grown silicon (Epi-Si) wafers by analyzing defects, stress, and crystallinity. Unlike conventional electrical property analysis, which is typically conducted post-process through device failure testing, this study demonstrated the potential for non-destructive and real-time assessment of thin film properties at the wafer stage using Raman spectroscopy. By comparing two 8-inch wafers fabricated under different deposition conditions, Raman shift and Full Width at Half Maximum (FWHM) were established as primary evaluation indicators to analyze the point-specific characteristics of the wafers. We applied multi-wavelength Raman spectroscopy with 532 nm and 405 nm laser to measure stress distribution of wafer - scale Epi-Si layers and compared it with wafer failure maps to demonstrate the validity of stress analysis of thin films using Raman spectroscopy. The residual stress and FWHM of epitaxially grown Si thin films were quantitatively analyzed for 9 points of Epi-Si. The point-by-point residual stress and crystallinity evaluations measured by Raman spectroscopy were in good agreement with the wafer failure map, and the stress variation in the failure region could be evaluated highlighting g potential of Raman spectroscopy enabling precise analysis across a broader range of samples and having the practical utility for non-destructive, early-stage assessment of thin film properties, as well as for the in-situ detection of defects and stress.

Graphical Abstract