Recent results from extreme ultraviolet lithography patterned mask inspection for 11 nm half pitch generation using projection electron microscope system
Extreme ultraviolet lithography (EUVL) is a promising technique for 1X nm half pitch (hp) generation lithography. The inspection of patterned EUVL masks is one of the main issues that must be addressed during mask fabrication for manufacture of devices with 11 nm hp feature sizes. We have already designed projection electron microscope (PEM) optics that have been integrated into a new inspection system called Model EBEYE V30 (where "Model EBEYE" is an EBARA's model code) and this system seems quite promising for 16 nm hp generation EUVL patterned mask inspection. The defect inspection sensitivity of this system was evaluated via capture of an electron image that was generated at the mask by focusing the image through the projection optics onto a time delay integration (TDI) image sensor. For increased throughput and higher defect detection sensitivity, a new electron sensitive area image sensor with a high speed data processing unit, a bright and stable electron source, and a simultaneous deflector for the image capture area that follows the mask scanning motion have been developed. Using a combination of synchronous deflection and mask scanning, the image can be integrated into both the fixed area image sensor and the TDI image sensor. We describe our experimental results for EUV patterned mask inspection using the above system. Elements have been developed for inspection tool integration and the designed specification has been verified. The system performance demonstrates the defect detectability required for 11 nm hp generation EUVL masks.
Photomask Japan