Material Processing with Cluster Ion Beams

团簇离子的碰撞过程远不同于单体离子的碰撞过程。团簇离子在固体表面碰撞的特殊性是所谓的“非线性现象”。据报道，固体表面上的损伤形成、溅射和化学反应具有独特的轰击效应。在毫微秒的时间尺度内，许多原子在微小的表面积上碰撞。因此，团簇组成原子与表面原子的每次碰撞都有望产生新的相互作用。这些密集的碰撞导致了高的溅射产额、表面光滑、浅注入和高的二次离子发射产额。团簇离子的表面光滑效应已被应用于许多材料。我们研究了团簇离子的辐照效应，团簇离子是几个到数千个的聚集体，十个大小的团簇注入到硅中。我们已经证明了与所谓的Decboran离子形成浅结。用透射电子显微镜(EM)和卢瑟福背散射(RBIS)对辐照区域进行了研究。团簇离子辐照的无序原子数比单体离子辐照的多一个数量级。辐照区域可以在低温下完全非晶化和再结晶，而不会造成任何损伤。在碳团簇辐照的情况下也发现了这些现象。

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.