Fundamental beam studies of deuterium and fluorine radical reaction kinetics on surfaces

Abstract

The abstraction reaction kinetics of two radical surface reactions were investigated on silicon, photoresist (PR), alumina, and quartz using a high vacuum beam system with independent beams of D and F atoms. Modulated beam mass spectrometry was used to measure the following heteronuclear abstraction probabilities from Si, PR, Al2O3, and SiO2 at 286 K: F atoms abstracting adsorbed D atoms from PR (γFD,PR=0.25); Si (γFD,Si=0.22); quartz (γFD,SiO2=0.18); alumina (γFD,Al2O3=0.12); and D atoms abstracting adsorbed F atoms from PR (γDF,PR<0.02); Si (γDF,Si<0.02); alumnia (γDF,Al2O3<0.02); and quartz (γDF,SiO2<0.02). These probabilities were also measured at 344 K. The rate of D abstracting F increased from below the limit of detection at 286 K to γDF,Si=0.05 on Si at 344 K, suggesting that this process is thermally activated, but no significant effect of temperature was observed for F abstracting D on any surface tested. Reactive site densities were also estimated for these surfaces: PR (σPR=2.0×1015/cm2), Si (σSi=2.0×1015/cm2), quartz (σSiO2=8.0×1014/cm2), and alumina (σAl2O3=5.0×1014/cm2).