In-situ Contamination Thickness Measurement by Novel Resist Evaluation System at NewSUBARU

Abstract

To reduce the influence of carbon contamination growth, which is the origin of the resist outgassing during extreme ultraviolet (EUV) exposure, it is necessary to study the relationship between the outgassing species from the resist and carbon contamination growth during EUV exposure. Thus a novel evaluation system which enable the measurement of the carbon contamination thickness on a Mo/Si multilayer witness sample by in-situ ellipsometry in the resist outgassing environment under EUV exposure was installed at the beamline in the NewSUBARU synchrotron radiation facility. The carbon contamination thickness on the witness sample measured by in-situ ellipsometry is in good agreement with those measured using an atomic microscope and by reflectivity measurement. In addition, it is found that the time dependence of the carbon growth on a witness sample is due to the difference in outgassing species from the resist samples during EUV exposure. Furthermore, for the model resist of poly(hydroxystyrene) containing the protectiive group of tertial butoxycarbonyl group with a photoacid generator (PAG) and a quencher, the time dependence of contamination thickness was mainly due to the decomposition of outgassing species of the tert-butoxycarbonyl group and the residual casting solvent, such as propyleneglycol monomethyl ether acetate. In order to evaluate the carbon contamination thickness measurement, the in-situ measurement system was moved to the 10.8-m-long undulator beamline. The EUV light intensity flux was estimated to be the same level as that required in high-volume manufacturing.