聚合物物理属性对离子注入效应的影响

聚合物导电性能差, 表面电荷积聚所产生的电容效应致使其表面电位衰减, 采用等离子体浸没离子注入对其表面改性是非常困难的. 建立了绝缘材料等离子体浸没离子注入过程的粒子模拟(PIC)模型, 实时跟踪离子在等离子体鞘层中的运动形态及特性并进行统计分析. 并基于PIC模型, 将聚合物表面的二次电子发射系数直接与离子注入即时能量建立关联, 研究了聚合物厚度、介电常数和二次电子发射系数等物理量对鞘层演化、离子注入能量和剂量的影响规律. 研究结果表明: 当聚合物厚度小于200 μ m, 相对介电常数大于7, 二次电子发射系数小于0.5时, 离子注入剂量和高能离子所占的份额与导体离子注入情况相当. 通过对聚合物表面离子注入剂量和高能离子所占份额的研究, 为绝缘材料和半导体材料表面等离子体浸没离子注入的实现提供了理论和实验依据.

Effect of physical properties of polymer on ion implantation

Plasma immersion ion implantation (PIII) of polymer materials is inherently difficult because the voltage across the sheath is reduced by the voltage drop across the insulator due to dielectric capacitance and charge accumulating on the insulator surface. The spatiotemporal evolutions of plasma sheath, energy and dose of ions are simulated by particle-in-cell (PIC) model for ion implantation into insulator materials. Statistical results can be achieved through scouting each ion motion in the plasma sheath. Based on the PIC model, the secondary electron emission (SEE) coefficient is determined according to the instant energy of implanting ions. Effects of thickness, dielectric constant and SEE coefficient on sheath evolution, dose and energy of incident ions are studied. The ion implantation doses and the share of high-energy incident ions are basically equivalent to the case of implantation of conductor ions, when the polymer thickness is less than 200 μ m, relative dielectric constant is more than 7, and SEE coefficient is less than 0.5. The numerical simulation of ion implantation into polymer can effectively provide a scientific and experimental basis for PIII of insulators and semiconductors.