Characterization of extreme ultraviolet lithography photoresists using advanced metrology and fitting techniques

As extreme ultraviolet lithography (EUVL) prepares to be incorporated into high volume manufacturing, many challenges must be addressed. Among these challenges, a need for photoresist improvement exists. The work described here will look into some of the problems and challenges facing EUV resists, in particular out-of-band (OOB) wavelengths of light and their interaction with photoresists. Studies have been completed on the effect of out-of-band light on photoresists. It is imperative that solutions to suppress the deep ultraviolet (DUV) OOB light be incorporated into next generation EUV production tools due to concerns of decreased performance of lithography, and an increase of outgassing contamination.;Testing is performed to better understand how an EUV resist clears in the DUV OOB region. There is an establishment of the clearing trends of various EUV photoresists between the 185 nm and 285 nm (out-of-band) wavelength range and their corresponding absorbance values. A correlation between the clearing of the resist, and the amount of energy absorbed per volume in the resist layer is inspected. Additionally, further information of whether the amount of photons per volume could be the clearing mechanism instead of the absorbed energy per volume is found. In the process of reviewing these points, methods of establishing fitting to contrast curves using parameters of absorbance and the absorbed energy per volume of a material are found. Current available literature is compared to our methods and assumptions. Both are evaluated for validity.