Photoresist (PR) etch rate kinetics were investigated for Olin i-line PR using a high-vacuum cl amber with independent beams of argon ions, oxygen ions,,and fluorine atoms. Etch yields were measured as a function of the fluorine atom/ion flux ratio for both ions. The etch yield of PR with oxygen ions was always higher than with argon, but the difference in yield between the two cases decreased as the F atom/ion flux ratio was increased. The effect of ion energy and ion angle of incidence on PR etching was also investigated. It was observed that the PR sputter yield increases linearly with the square root of ion energy for both oxygen and argon ions. The extrapolated threshold energies for sputtering were determined for both ions: E-O2(th) (+) (theta = 45degrees)= 6 eV, E-Ar+(th) (theta =45degrees)=36 eV. The angular dependence of the PR etch yield (EY) was consistent with. that typically observed for physical sputtering, even for F atom/Ar ion flux ratios as high as 150. These EY results were incorporated into a generalized site balance model of the PR etching process.