Development of internal-antenna-driven large-volume RF plasma sources for plasma-based ion implantation

Large-area and high-density RF plasmas at 13.56 MHz have been produced in a discharge chamber with 400 mm inner diameter and 200 mm height by inductive coupling of an internal-type double half-loop antenna (320 mm diameter). The present study has been carried out to develop the basic discharge techniques that can be applied to the production of high-density and large-volume plasmas for a variety of plasma-based ion implantation (PBII) processes. The plasma source could be operated stably at RF input powers up to 2.5 kW to attain a plasma density as high as 5×1011 cm−3 at argon pressures of approximately 1 Pa. It has been demonstrated that a high-plasma density can be obtained using the low-inductance internal antenna configuration for effective suppression of the electrostatic coupling. Discharge experiments in nitrogen and hydrogen resulted in a radially uniform plasma production with density as high as 5–9×1010 cm−3.