采用三维PIC模型仿真研究了等离子体浸没离子注入过程中工件高度变化对鞘层扩展动力学和离子注入效果的影响。模拟结果表明,随着工件高度减小,中心水平截面内鞘层扩展速度明显下降,鞘层最终尺寸也明显减小。随着工件高度减小,工件上表面的注入剂量峰幅值明显增大,表面注入剂量均匀性则显著下降。随着工件高度减小,工件上表面的离子垂直入射面积和高能离子注入面积略有减小。这是由于工件高度减小造成鞘层曲率半径减小,弯曲的鞘层增大了离子聚焦现象将更多离子聚焦注入到工件边角附近位置。随着工件高度减小工件侧壁上的注入剂量峰幅值明显增大,而且工件棱线上的剂量数值也显著增大,且均匀性更好。
The influence of the height of the 3-D rectangular target on the plasma immersion ion implantation(PIII) was studied via the plasma simulation,performed with the 3-dimensional particle-in-cell(PIC) software package.The simulated results show that the height of the target significantly affects the characteristics of the plasma and the PIII performance.For instance,the decrease of the height resulted in a rapid decrease of the sheath expansion rate,a significant reduction of the sheath thickness,a much higher peak of the implantation rate,a deterioration of implantation uniformity,and slight decreases of the surface areas for both the high energy and the vertically impinging ions.Moreover,the lowering of the height markedly improves the implantation both on the sidewalls,and at the edges of the work-piece.Possible mechanisms were also tentatively discussed.