Measurement of subsurface damage in silicon wafers

Silicon wafers are used as the substrates upon which over 90% of the semiconductor devices are manufactured. A series of processes are needed to manufacture silicon wafers. Some processes will induce subsurface damage that should be eliminated by subsequent processes. Therefore, the assessment of subsurface damage is critically important to optimize manufacturing processes and ensure high quality of silicon wafers. This paper presents a summary of available measurement methods for subsurface damage (SSD) in silicon wafers. The measurement methods covered include cross-sectional microscopy, preferential etching, angle lapping or angle polishing, Xray diffraction, micro-Raman spectroscopy, and laser scattering. Laser scattering has been successfully used to detect surface and near-surface defects in ceramics. Preliminary study of applying laser scattering on SSD measurement in silicon wafers shows that laser scattering is very promising as a nondestructive measurement technique to assess subsurface damage in silicon wafers.