Formation of OH species from ethylene and highly concentrated ozone gases

Abstract For applying an alternative to resist removal, we analyzed and confirmed that electronically excited hydroxyl (OH) radical is produced from the reaction of highly concentrated ozone (O 3 ) gas with ethylene (C 2 H 4 ) gas for the resist removal processing at 10 2 Pa pressure. Fourier-transform infrared absorption spectroscopy revealed that the products of the initial part of the reaction are H 2 O, CO, CO 2 , an aldehyde, and an OH-containing species. Mass spectrometry confirmed the aldehyde to be formaldehyde (HCHO) as was reported. Ultraviolet-visible emission spectroscopy confirmed the OH-containing species to be electronically excited OH radical formed as an initial reaction intermediate, with its emission peak at 310 nm in the chemiluminescence emission spectrum. A second alkene molecule, isobutene ( i -C 4 H 8 ), was also found to produce the same OH species under the same experimental conditions, albeit at a lesser amount than that produced with C 2 H 4 . This oxidant can provide a novel resist removal method.