Articles you may be interested inPhase defect characterization on an extreme-ultraviolet blank mask using microcoherent extreme-ultraviolet scatterometry microscopeIn extreme-ultraviolet (EUV) lithography, defect-free mask production is a critical issue for highvolume manufacturing. For mask inspection and metrology, we have developed a coherent EUV scatterometry microscope (CSM). It is a simple lensless system. An aerial image of the mask pattern is reconstructed with iterative calculation based on coherent diffraction imaging. Periodic patterns, aperiodic patterns, and phase structures were reconstructed well by the CSM. A defect in a line-and-space pattern was detected as a diffraction signal. The aerial image of the defect is also reconstructed. This paper demonstrates the capability of the CSM to observe complex diffraction amplitudes directly from the pattern and the defect.

Extreme ultraviolet interference lithography was carried out at the long undulator beamline in NewSUBARU. It was confirmed that the spatial coherence length is 1.1 mm using a 10-µm-wide slit in the Young's double slit experiment. A 25-nm half pitch (hp) resist pattern was successfully replicated by extreme ultraviolet interference lithography (EUV-IL) utilizing a two-window transmission grating pattern of a 50-nm line and space (L/S). For the replication of a 20-nm L/S resist pattern by EUV-IL, we contrived a fabrication process that is suitable for a transmission grating pattern of 40-nm L/S and smaller. Employing a hard-mask process with a silicon dioxide (SiO2) layer on a tantalum–nitride (TaN) layer in the fabrication of a two-window transmission grating, we successfully achieved five times larger dry-etch selectivity in comparison with a non-hard-mask process. As a result, we confirmed the ability to apply this process to a 40-nm hp grating.

No abstract