轴承滚珠等离子体浸没离子注入过程的数值模拟

 利用轴对称PIC模型对轴承滚珠等离子体浸没离子注入（PIII）过程进行了数值模拟，对归一化电势的扩展情况进行了研究。在滚珠批量处理过程中，为了避免相邻滚珠周围鞘层的相互重叠对注入均匀性造成不良影响，对滚珠在靶台上摆放的最小距离进行了数值计算，计算结果表明：在电压为－40kV, 氮等离子体密度为4.8×10⁹ cm^-3，脉冲宽度为10μs时，滚珠摆放的最小距离应大于34.18cm。分析了滚珠圆周方向注入剂量的分布情况，针对静止滚珠改性处理后剂量分布很不均匀的问题，通过旋转靶台使滚珠注入均匀性明显得到改善。利用朗谬尔探针测量了滚珠周围鞘层扩展的情况测量，模拟结果和实验测量结果相吻合，最大相对误差小于8.4 %。

Numerical simulation of bearing balls in the plasma immersion ion implantation process

The process of bearing balls in the plasma immersion ion implantation(PIII) was simulated using a 2-dimensional particle-in-cell (PIC) model. The distributions of normalized potential and dose were studied. In order to avoid overlap of sheaths between different balls in batch process, the minimum distance between two neighboring balls was calculated. When the voltage is -40 kV, plasma density is 4.8×10~9cm~(-3) and pulse width is 10μs, the minimum distance between two balls should be 34.18 cm. In addition, the dose distribution along the circumference of the ball is non-uniform. Consequently, a revolving substrate was used to improve the uniformity. Furthermore, to evaluate the model, the expansion process of sheath was measured using a Langmuir probe. Experimental results agree with the calculated value, and the maximum relative error is less than 8.4%.