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High-reflectance phase-shifting mask (HR-PSM) is studied for patterning 36nm-pitch logic contact holes and compared with other mask absorbers in terms of imaging performance (ILS, LCDU, MEEF, etc.) and exposure dose. To this end, wafer-data-calibrated EUV resist models for CAR and MOR are used. Our simulation results show that a HR-PSM produces dark-field images at large mask CD. However, as mask CD decreases, the tone of the images is reversed and bright-field images of good contrast can be generated. Based on this observation, a HR-PSM plus MOR patterning approach is proposed for through-pitch logic contact hole applications with a minimum pitch equal to 36 nm. We show that this approach demonstrates multiple enhancements in terms of through-pitch performance and enables us to extend the practical resolution of logic contact holes below the pitch of 40 nm using the 0.33NA EUV scanner.

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