Quantification of outgassing of C-, Si-, and S-containing products during exposure of photoresists

Because volatile species containing Si and S desorbed from photoresists during exposure to light can irreversibly damage optical elements inside a photolithography tool, accurate quantification of vapor fluxes is essential to evaluate risk. The authors compare measurements using two vapor-collection methods (gas and ion chromatographies) and one solid state analysis method (secondary ion mass spectrometry) to characterize outgassing from two silicon-containing and two all-organic 193nm photoresists during exposure at atmospheric pressure. Results from all three techniques are in good general agreement with the notable exception of Si-containing products. Investigation of the influence of the gas atmosphere above the resist during exposure reveals that gas-surface interactions involving oxygen and perhaps water are a previously unrecognized mechanism for release of Si during exposure of otherwise inert polymers. This result shows that it is essential to take the gas environment inside the photolithographic...