Investigation of Sensitivity of Extreme Ultraviolet Resists to Out-of-Band Radiation

A method to evaluate the sensitivity of photoresists used for extreme ultraviolet (EUV) lithography has been developed. EUV sources produce out-of-band radiation and the reflective optics used in EUV tools reflect some of this out-of-band light on the wafer plane. The effect of exposing these photoresists to this unwanted light can reduce the image contrast on the wafer, and thereby reduce the image quality of the printed images. To examine the wavelengths of light that may have an adverse effect on these resists, a deuterium light source mounted with a monochromator has been designed to determine how sensitive these photoresists are to light at selected wavelengths in the range 190-650 nm.