Secondary Ion Generation Mechanism Studied by Multi-photon Excima Laser Ionization

我们成功地开发了多光子电离系统，使我们能够进行定量的二次离子质谱以及溅射粒子的速度分布的精确测量。下图为系统示意图。典型的处理条件为：激光束尺寸0.9m × 0.3m，激光强度33 mJ，离子束清洗1-3 μ A，溅射粒子处理10 - 30 nA，真空度1 × 10 ~（-3）<-9>Torr<A1><plus-minus>. (2)这种定量表面分析方法稳定性高，对表面粗糙度和真空度的变化几乎不敏感。(3)本文首先观察到在Ar ~+离子轰击下Cu-Ni合金溅射原子的速度分布与离子剂量的关系不大。(4)分析表明，一次Ar离子注入到Cu-Ni合金表面，确实改变了合金的实际表面结合能，即表面结合能。例如，高剂量导致表面结合能降低。

We have succeeded to develop Multi-Photon Ionization System, which enables us to perform quantitative secondary ion mass spectroscopy as well as precise measurement of velocity distribution of sputtered particles. Figure shown below is schematic diagram of the systems. Typical conditions of the manurement are as follows : Laser beam size, 0.9m x 0.3m ; Laser intensity 33mJ, ion be&n 1-3, muA for cleaning and lO-3OnA for the manurement of sputtered particles ; Vacuum lxlO^<-9>Torr.The results are summarized ;(1) Quantitative surface analysis for Al-Cu alloys have indicated that concentration of AI is determined so accurately as C_<A1>=25.4<plus-minus>0.446% for true concentration 26%.(2) This type of quantitative surface analysis can be performed with high stability almost unsensitive to the variation of surface cont&nination and vacuum deterioration.(3) It has, first, bean observed that velocity distribution of sputtered atoms from Cu-Ni alloy under Ar+ ion bonbardment is slightly dependent on the ion dose.(4) The analysis has led to conclusion that the primary Are ions implanted in the surface of Cu-Ni alloy do change the actual surface binding energy, i. e., high dose leads to lower the surface binding energy.