The use of a high-voltage discharge at low pressure for 3D ion implantation

Abstract

A high-voltage pulse gas discharge burning on the left branch of the Paschen curve is used as a basis for three-dimensional ion implantation (3DII). The 3DII technique uses a scheme whereby the target is the cathode and the anode is a vacuum chamber filled with working gas in the pressure range 0.15–2.0 Pa. The external characteristics of the gas discharge are described. Results of a probe investigation of the main discharge parameters are presented. It is found that gas discharge has a quasi-stationary spatial structure with a thin layer (less than 1 cm) of cathode fall where all voltage applied to the electrodes drops. Ions effectively accelerate in cathode fall in a collisioniess mode. A high-energy ion current density on the cathode surface is measured. Possible mechanisms of generation of ion flux on the cathode are discussed. It is shown that the near-anode plasma is not a general supplier of ions on the cathode. The main parameters measured and the discharge features make it possible to use the 3DII technique for technological applications.