Kenichi Suematsu

Study of extreme ultraviolet lithography patterned mask inspection tool for half-pitch 11-nm node defect detection performance

Abstract. Extreme ultraviolet lithography (EUVL) patterned mask defect detection is one of the major issues to overcome for realization of EUVL-based device fabrication. We have designed projection electron microscope (PEM) optics that have been integrated into a new inspection system called EBEYE-V30 (“Model EBEYE” is EBARA’s model code), and the PEM system performs well in half-pitch (hp) 16-nm node EUVL patterned mask inspection applications. We also discuss the extendibility of this system to 11-nm node defect detection. The progress made in the performance of the PEM optics is not simply about producing an image sensor with higher resolution but is also about improvement of the image processing to enhance the defect signal. A high-speed image sensor, a high-speed image-processing circuit, and a bright and stable electron source are necessary for hp 11-nm defect inspection. We describe the experimental results for EUVL patterned mask inspection using the above system for the hp 11-nm node. Programmed hp 11-nm defects (equivalent to 44 nm on the mask) are used for defect detection sensitivity evaluation. Defects as small as 16 nm on the mask could be detected using the current PEM system configuration.

Extreme ultraviolet patterned mask inspection performance of advanced projection electron microscope system for 11nm half-pitch generation

Novel projection electron microscope optics have been developed and integrated into a new inspection system named EBEYE-V30 (“Model EBEYE” is an EBARA’s model code) , and the resulting system shows promise for application to half-pitch (hp) 16-nm node extreme ultraviolet lithography (EUVL) patterned mask inspection. To improve the system’s inspection throughput for 11-nm hp generation defect detection, a new electron-sensitive area image sensor with a high-speed data processing unit, a bright and stable electron source, and an image capture area deflector that operates simultaneously with the mask scanning motion have been developed. A learning system has been used for the mask inspection tool to meet the requirements of hp 11-nm node EUV patterned mask inspection. Defects are identified by the projection electron microscope system using the “defectivity” from the characteristics of the acquired image. The learning system has been developed to reduce the labor and costs associated with adjustment of the detection capability to cope with newly-defined mask defects. We describe the integration of the developed elements into the inspection tool and the verification of the designed specification. We have also verified the effectiveness of the learning system, which shows enhanced detection capability for the hp 11-nm node.

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.

Patterned mask inspection technology with Projection Electron Microscope (PEM) technique for 11 nm half-pitch (hp) generation EUV masks

High-sensitivity EUV mask pattern defect detection is one of the major issues in order to realize the device fabrication by using the EUV lithography. We have already designed a novel Projection Electron Microscope (PEM) optics that has been integrated into a new inspection system named EBEYE-V30 (“Model EBEYE” is an EBARA’s model code), and which seems to be quite promising for 16 nm hp generation EUVL Patterned mask Inspection (PI). Defect inspection sensitivity was evaluated by capturing an electron image generated at the mask by focusing onto an image sensor. The progress of the novel PEM optics performance is not only about making an image sensor with higher resolution but also about doing a better image processing to enhance the defect signal. In this paper, we describe the experimental results of EUV patterned mask inspection using the above-mentioned system. The performance of the system is measured in terms of defect detectability for 11 nm hp generation EUV mask. To improve the inspection throughput for 11 nm hp generation defect detection, it would require a data processing rate of greater than 1.5 Giga- Pixel-Per-Second (GPPS) that would realize less than eight hours of inspection time including the step-and-scan motion associated with the process. The aims of the development program are to attain a higher throughput, and enhance the defect detection sensitivity by using an adequate pixel size with sophisticated image processing resulting in a higher processing rate.