Performance data of a new 248-nm CD metrology tool proved on COG reticles and PSMs

A new CD metrology system with 248 nanometer (nm) (DUV) illumination is the subject of this paper. The system configuration and major component improvements is described. Test measurements on chrome-on-glass (COG) and attenuated phase shift masks (Att-PSM) were performed demonstrating optical resolution of 100 nm for inspection and 200 nm for CD metrology. The test measurements also demonstrated improved CD linearity down to approximately 300 nm and long term repeatability performance in the 2 nm realm.