工件靶台复合加速离子注入系统中的靶台偏压效应

摘要

The effect of bias voltage applied to target on the ion dynamic behavior of hybrid acceleration ion implantation based on target-acceleration is investigated by PIC/MCC simulation. Our interests are mainly focused on the variations of ion energy,implantation dose,and incident angle,as well as implantation region on target with different amplitudes of bias voltage. The results show that the potential contours above the target with negative pulse bias voltage become curved because of downstream movement of beam-line ions. Simultaneously,the gradually changing electric field also affects the trajectories of flying ions. The potential edge (0V) expands forward and the region influenced by electrical field of target increases with increasing the amplitude of bias voltage. The dose and average energy of ions implanted into the surface of target increase due to the increasing velocity of ions,which are effectively accelerated by the bias voltage applied to the target. Although some of ions within curved electric field lines deflect,the average incident angle is still relatively low and the amplitude of bias voltage has no significant influence on the incident angle. Due to the deflection of beam-line ions induced by the electric filed of target,the area of implantation region on the surface of target with higher bias voltage is larger than that with lower bias voltage.%采用PIC/MCC模型,通过数值模拟的方法研究了束线离子和靶台复合加速离子注入过程中靶台偏压大小对注入过程离子动力学行为的影响,重点考察了不同偏压作用下离子的注入能量、注入剂量、注入角度以及注入范围的变化.结果表明,靶台上施加脉冲偏压后,在束流离子的作用下空间电荷分布发生变化,束流正下方的电势线会发生凹曲,凹曲的电场同时又作用于空间中的带电粒子,影响粒子的运动；靶台偏压越高,零电势线距离靶台越远,靶台电场对离子的作用范围越大.离子的注入剂量、注入能量随着靶台偏压的增大而增大,而偏压对离子注入角度的影响并不大,大部分离子都以垂直入射的方式注入到靶台表面.另外,离子注入到靶台上的面积会因束流离子在靶台电场中飞行偏转而增大,并且偏压越大注入面积增大越明显.