采用三维粒子模拟模型研究了有限尺寸方靶等离子体浸没离子注入过程中的鞘层动力学行为,得到了鞘层尺寸和方靶表面的注入剂量、注入能量以及注入角度等信息,并与二维无限长方靶注入结果进行了对比.模拟结果表明,与无限长方靶不同,有限尺寸方靶周围鞘层很快扩展为球形,但鞘层厚度明显减小.在模拟的50ω-1pi时间尺度内靶表面注入剂量很不均匀,中心区域注入剂量最小,四个边角附近位置注入剂量最大.这种剂量不均匀性是由于鞘层扩展为球形,使得鞘层内离子被聚焦并注入到边角附近所致.方靶中心区域离子接近垂直注入,并且注入能量超过最大注入能量的90%;而在边角位置离子以45°左右的入射角度注入到靶表面,注入能量仅仅约为最大注入能量的50%.
Plasma immersion ion implantation (PIII) of the square target with finite length is simulated using a three-dimensional particle-in-cell (PIC) plasma simulation in this paper.The incident dose,the impact angle and the implanted energy on the target surface are investigated.The results show that the sheath around the square target with finite length becomes spherical rapidly during PIII.And the three-dimensional sheath width is small apparently compared with the one simulated by two-dimensional PIC.And it is found that the three-dimensional ion dose is not evenly distributed on the target surface during simulation time (50ω-1pi) in this work.The dose is smallest in the center of the target,and it is largest near the corner.This is due to spherical sheath where ions are focused and accelerated into near the corner.In the central zone,the ion incidence is nearly normal to the surface,and the impact average energy exceeds 90% of the maximum.But the impact angle near the corner is always nearly 45°,and the implanted energy is only about 50% of the maximum.