EUV resist outgassing release characterization and analysis

The reduction of extreme ultraviolet (EUV) resist outgassing to minimize or prevent possible contamination of EUV exposure tools is viewed as an important factor in the development of EUV resists. In this paper, a detailed evaluation/comparison of the pressure rise method (evaluation based on the measured pressure variations due to the released resist outgassing) and the gas chromatography–mass spectroscopy (GC–MS) quantification methods is discussed. The application of compensation-values based on the factors affecting each of these methods was also investigated. The ‘relative sensitivity of ion gauge’ for the pressure rise method and an approximated amount of CO2 (which is not collectable by desorption tubes) for GC–MS was used for the compensation of resist outgassing quantification. With the application of these compensation-values, an improved and small difference between evaluation methods of 4.7–16 times is obtained in contrast with a 34–107 times difference without compensation. Moreover, the resist outgassing difference caused by a variation in the resist chemical composition (protecting ratio, photo-acid generator (PAG) and quencher content) shows the same trend regardless of evaluation method utilized, even with compensation.