Laser-induced surface acoustic wave is a new surface damage detection technology, which uses the transient thermal effect of pulse laser to excite the surface acoustic wave on the sample surface. The damage of machined surface layer will cause the velocity change of laser-induced surface acoustic wave. This phenomenon is introduced into the evaluation of the surface layer damage of silicon wafers in this paper. The three-dimensional propagation model of the single-layer structure is extended to the double-layer structure, and it is proved that the gradient change of the surface layer damage will change the trend of velocity curve. In order to characterize the change of velocity curve, the surface layer damage coefficients are introduced. The cross-sectional transmission electron microscope (TEM) image of the lapped silicon wafer shows that the surface of the silicon wafer after lapping will produce a surface damage layer. The test data of the nanoindenter shows that the modulus of the surface damage layer is lower than that of the bulk material. The modulus estimated by dispersion curve is very close to the data measured by nanoindenter, indicating that the dispersion curve can truly reflect the damage degree of silicon wafer surface layer.

激光诱导表面声波是一种新型的表面损伤检测技术，它利用脉冲激光的瞬态热效应在样品表面激发表面声波。加工表面层的损伤会引起激光诱导表面声波的速度变化。本文将这种现象引入到硅片表层损伤的评价中。将单层结构的三维传播模型推广到双层结构，证明表层损伤的梯度变化会改变速度曲线的趋势。为了表征速度曲线的变化，引入了表层损伤系数。研磨后的硅片的横截面透射电子显微镜（TEM）图像显示，研磨后的硅片表面会产生表面损伤层。纳米压痕仪的测试数据表明，表面损伤层的模量低于块体材料的模量。色散曲线估算的模量与纳米压痕仪测得的数据非常接近，说明色散曲线能够真实反映硅片表层的损伤程度。