Abstract
We investigated the removal of positive-tone novolak resist, ArF resist, and positive-tone novolak resists into which B, P, and As ions were implanted with a dose of 5X1014atoms/cm2 at an acceleration energy of 70keV (forming ion-implanted resists) using Xe2 excimer UV light. There was an optimum UV irradiation distance with respect to the removal rate since oxygen could not penetrate into the UV irradiation space when the UV irradiation distance was 0mm, and the intensity of the UV light decayed when the UV irradiation distance was too great. It was confirmed that the resist was not removed in a nitrogen environment because ozone and oxygen radicals were not generated. There is an optimum substrate temperature for the removal rate the same as for the UV irradiation distance. It was considered that the reactivity between resist and the ozone and oxygen radical was enhanced but ozone concentration decreased by decomposition of the ozone to oxygen molecules with a rise in substrate temperature. Under the optimum UV irradiation conditions, the UV irradiation time for complete removal of ArF resist (0.15μm thick) was 4min. Although the ion-implanted resists were difficult to remove by conventional methods, B- and P-ion-implanted resists were removed by Xe2light.
