基片表面缺陷粒子在激光波束作用下的辐射力分析

Analysis of Radiation Forces Exerted on Defect Particle on the Wafer by a Laser Beam

针对基片无损检测工作中缺陷粒子的清除问题,基于广义米氏理论,结合球形缺陷粒子对激光波束的散射理论,研究了沿基片水平方向入射高斯波束对介质球缺陷粒子的辐射力。根据连带勒让德函数及三角函数的正交关系,给出作用在高斯波束中介质缺陷球体粒子上的横向以及轴向辐射力的解析表达式,并分析不同参数对辐射力的影响。结果表明,随激光束腰半径的减小,辐射力峰值变大;随束腰半径增大,光轴的能量降低,散射力减小;随粒子折射率减小,散射力逐渐减小。工程上可通过减小激光波束束腰半径加大激光能量,以便更有效地清除缺陷粒子;亦可通过对辐射力的定量分析实现缺陷材质的检测。

Based on generalized Lorenz-Mie theory, the radiation forces exerted on defect particle on the wafer by a laser beam are derived combing the scattering theory about sphere particle to clean the defect particle in the optical nondestructive examination. According to relationship between spherical vector wave functions and triangle functions, the analytical expressions of the axial radiation force and the transverse radiation force exerted on defect particle by an Gaussian beam are given and the influences of many factors on the radiation forces are analyzed numerically in details. The results show that the maximum radiation forces become larger with the particle radius becoming less. The energy of optical axis and scattering forces become less with the particle radius becoming larger. The smaller the dielectric constant, the smaller the radiation force. In the project, the smaller beam waist widths is used with much more energy to clear the defect particle more efficiently. In addition, the defect particle material is detected by quantitative analysis to radiation forces.