Material Processing with Cluster Ion Beams

簇离子的冲击过程与单体离子的冲击过程相去甚远。团簇离子在固体表面碰撞的特性被称为“非线性现象”。在固体表面的损伤形成、溅射和化学反应中有独特的轰击效应。在飞秒时间尺度内，许多原子撞击在很小的表面上。因此，期望团簇组成原子与表面原子的每次碰撞产生新的相互作用。这种密集的碰撞使溅射成品率高、表面光滑、浅注入和二次离子发射成品率高。簇离子的表面平滑效应已应用于许多材料。我们研究了辐照对簇离子的影响，簇离子是几到几千个的聚集体。将10倍大小的硼团簇植入硅中。我们已经证明了所谓的Decaboran离子形成的浅结。用透射电镜（EM）和卢瑟福背散射（RBIS）对辐照区进行了研究。簇离子辐照的无序原子数比单体离子辐照的无序原子数高一个数量级。辐照区在低温下完全无定形和再结晶，无损伤。在碳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.