CHF3 dual-frequency capacitively coupled plasma

Abstract

This paper investigates the intermediate gas phase in the CHF3 dual-frequency capacitively couple plasma (DF-CCP) driven by the high-frequency (HF) of 1356 MHz，2712 MHz or 60 MHz and the low-frequency (LF) of 2 MHz power sources，which was used to etch the SiCOH low dielectric constant (low-k) films. The increasing of 2 MHz LF power led to the increase of F radical concentration，and the increasing of HF frequency from 1356 MHz and 2712 MHz to 60 MHz led to the increase of CF2 concentration and a poor spatial uniformity of F radical between the electrodes. According to the electron temperature distribution at different LF power and HF frequency，and the dependence of ion energy on the high frequency，the CF2radicals were found to come from the CHF3 dissociation by the electron-neutrals collisions，and the F radical from the CHF3 dissociation induced by the ions-neutrals thermal collisions.