The effect of fluorine atoms on silicon and fluorocarbon etching in reactive ion beam etching

Abstract

Silicon, polymethylmethacrylate, polyvinylidenefluoride, and polytetrafluorethylene were etched with a reactive ion beam of CF4+NF3 mixtures, to simulate the effect of increasing fluorine atom concentration on polymer etching. We hypothesize that fluorocarbon deposits observed on the Si surface after beam etching are due to a lack of reactive neutrals, namely, fluorine atoms. We show that by increasing the % NF3 from 0% NF3 (F/C=4) to 50% NF3 (F/C=7) the etch rate of Si and the polymers increased. Also the polymer etch rates appear to be composition dependent. Fluorine atom intensity(7037 Å), monitored by optical emission spectroscopy, increased as NF3 was added to CF4. A comparison between reactive ion etched and reactive ion beam etching polymers was performed using electron spectroscopy for chemical analysis.