Electron temperature dependence on electrode layer characteristics in low-pressure RF discharge

Abstract

Summary form only given. Low-pressure RF discharges are often applied to etch semiconductor materials, to deposit diamond-like films, to pump gas lasers etc. Electron temperature T/sub e/ in the quasineutral plasma is one of the important characteristics of RF discharge. This paper reports on the relation found between T/sub e/ and electrode layer parameters for collisional and collisionless cases. We consider the collisional case when the mean free path of an ion in the electrode layer is less than the layer thickness d/sub S/. Then using the expression for the ion current density in the layer it is easy to obtain T/sub e/=C/sub 1//spl nu//sub i/pd/sub S/, where /spl nu//sub i/ is ion velocity in the layer, p is gas pressure, C/sub 1/ is constant. For the collisionless case, i.e. when an ion crosses the electrode layer without any collisions with neutral gas molecules, we employ the expression for the layer thickness d/sub S/ and the discharge current density J/sub 0/. Then T/sub e/ in the quasineutral plasma is related with d/sub S/, constant voltage drop in the layer V/sub c/ and the plasma density at the layer boundary n/sub i/ by an expression T/sub c/d/sub S//sup 4/=C/sub 2/V/sub c//sup 3//n/sub i//sup 2/, C/sub 2/=const.