Study of advanced mask inspection optics with super-resolution method for next generation mask fabrication

摘要

The lithography potential of an ArF (193nm) laser exposure tool with high numerical aperture (NA) will expand its lithography potential to 45nm node production and even beyond. Consequently, a mask inspection system with a wavelength nearly equal to 193nm is required so as to detect defects of the masks using resolution enhancement technology (RET). A novel high-resolution mask inspection platform using DUV wavelength has been developed, which works at 199nm. The wavelength is close to the wavelength of ArF exposure tool. In order to adapt l?9nm optics for hp2x nm node and beyond defect detection on next generation mask with appropriate condition, further development such as the illumination condition modification technique has been studied. The illumination optics has the advantageous feature that super-resolution method is applied by adding the optics. To evaluate the super-resolution effect of illumination condition control optics, the interaction of light with mask features is calculated rigorously using R.CWA (Rigorous Coupled-Wave Analysis) method. In this paper, image contrast enhancement effect using newly designed super-resolution optics which is applied to transmitted and reflected light image acquisition system are presented with simulation and experiment.