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 4.8×109cm-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 cal