The Monitor Strategies of Lens Flare for Nikon ArF and KrF Scanner Machines: Simulated Results and Discussion

Flare is a problem that has been known for some time on 248nm KrF scanner but has grown in importance on 193nm ArF systems. This paper discusses the strategy of monitoring the level of optic system flare in lithographic scanner KrF and ArF machines in the lithography process. Based on the optical simulated result, it is recommended to employ both the dose-to-clear Kirk method for large square patterns and the critical dimension uniformity (CDU) monitor method for the dense line/space patterns to tracking changes of project lens flare in lithographic scanner tools. The impact factor of flare in monitor process, such as the mask transmission rate, the illumination condition and the monitor pattern type selection, are also discussed in this paper.