Deposition in Dry-Etching Gas Plasmas

Abstract

Polymer deposition on Si and SiO₂ surfaces has been investigated in CH₂F₂, CHF₃, CF₄, and CHClF₂ gas plasmas, using a microwave plasma etching system. The dependence of the deposition rate on gas pressure, RF bias power, and substrate temperature was measured at a temperature between -120°C and 150°C. The deposition rate increased with decreasing temperature in CH₂F₂, CHF₃, and CHClF₂ plasmas. The deposition of polymers occured only below -60°C in the CF₄ plasma. The obtained dependence of the deposition rate on gas pressure was examined in terms of the volume of adsorbed particles. X-ray photoelectron spectroscopy measurement showed that the number of bondings between C and F atoms in deposited polymers increases with decreasing temperature and RF power, and increasing gas pressure.