Material Processing with Cluster Ion Beams

团簇离子的碰撞过程与单体离子的碰撞过程相差甚远。团簇离子在固体表面碰撞的特殊性是所谓的“非线性现象”。在固体表面上的损伤形成、溅射和化学反应中，已经报道了独特的轰击效应。许多原子在飞秒时间尺度内撞击小表面区域。因此，预期团簇组成原子与表面原子的每次碰撞的新的相互作用。这些密集碰撞导致高的溅射产率、表面平滑、浅注入和高的二次离子发射产率。团簇离子的表面平滑效应已被应用于许多材料。我们研究了硼原子团簇离子的辐照效应，硼原子团簇是由几个到几千个原子团簇组成的。我们已经证明了浅结形成与所谓的十硼离子。用透射电子显微镜（EM）和卢瑟福背散射（RBIS）研究了辐照区域。团簇离子辐照产生的无序原子数比单体离子辐照高一个数量级。辐照区在低温下可以完全非晶化和再结晶而无损伤。这些现象在碳团簇辐照的情况下也被发现。

An impact process of a cluster ion is far from monomer ion impact process. The peculiarity of the cluster ion collision on solid surfaces is the so-called "nonlinear phenomena". Unique bombardment effects have been reported for damage formation, sputtering and chemical reaction on solid surfaces. Many atoms impact on small surface area within femlo-second time scale. Therefore, a new interaction of each collision of the cluster constituent atoms with the surface atoms is expected. These dense collisions cause high yield of sputtering, surface smoothing, shallow implantation and high yield of secondary ion emission. The surface smoothing effect of cluster ions has been applied to many materials. We have studied irradiation effects on cluster ions, which are the aggregates of a few to thousands.Boron clusters with the size of ten are implanted to silicon. We have demonstrated shallow junction formation with so-called Decaboran ions. The irradiated region was investigated with EM(Transmission Electron Microscope) and RBIS(Rutherford Back scattering). The number of disordered atoms with cluster ion irradiation is an order of magnitude higher than that with monomer ion irradiation. The irradiated region can be completely amorphousized and recrystallized at low temperature without any damages. These phenomena are also found in the case of carbon cluster irradiation.