Enhancement of implantation efficiency by grid biasing in radio-frequency inductively coupled plasma direct-current plasma immersion ion implantation

Direct-current plasma immersion ion implantation (dc-PIII) is an emerging method for the treatment of planar samples and particularly attractive as an efficient and economical technique to fabricate silicon-on-insulator. In this article, we report the use of grid biasing to enhance the implantation efficiency such as implantation current density. Experiments in argon plasma show that the implantation current density varies with the biased voltage (Vg), is higher at Vg⩾+30 V or Vg⩽−40 V than at Vg=0, and is saturated at Vg⩾+50 V or Vg⩽−50 V at a pressure of 0.2 mTorr. The implantation current density is always higher at Vg=+50 V than at Vg=0 at different pressure and radio-frequency (rf) power. Moreover, the implantation current density increases with the rf power and pressure at both 0 and +50 V biasing. The results of our particle-in-cell simulation and global model show that the observed phenomenon is partly due to the variation of the plasma density with the bias, and the variation in the shape of emitted plasma surface with the bias is clearly illustrated by our experimental results. Similar results are observed for hydrogen plasma.