Creation of a degraded layer on the surface of photoresist by radical irradiation

A novel mechanism of the inclination of a photoresist mask based on the experimental evaluation of the change in the quality of the irradiated surface layer of a material was proposed. In this proposed mechanism, the irradiation of oxygen and fluorine radicals generates a very thin degraded surface layer with a high tensile stress and causes the inclination of the mask. It was found that a very thin (approximately 5 nm thick) layer with a high tensile stress appeared after the irradiation of radicals on the surface of the photoresist mask. X-ray photoelectron spectroscopy (XPS) confirmed that irradiation of either of these radicals generates a very thin degraded layer on the photoresist surface.