Selete launched a development program on EUV lithography and related mask technology in April 2006. The program is based on the concept of "lithography design and integration." It covers a wide range of areas that require further effort to get EUVL ready for volume production and was formulated on the basis that the issues should be considered from a variety of standpoints, such as acceleration of the development of key lithographic components, verification that EUVL is actually suitable for mass production, the construction of mask infrastructure, and the improvement of EUV-specific reliability and productivity. Two exposure tools have been installed as basic infrastructure: the small-field exposure tool (SFET) and the full-field exposure tool (EUV1). The objectives of the SFET installation are acceleration of the development of resist materials and processes, optimization of the mask structure and materials, and the evaluation of the exposure tool technology with regard to such things as imaging performance, stability, and the lifetimes of the optics and source components. The objective of the EUV1 installation is to demonstrate that lithography integration is a viable path to making EUV lithography a practical production technology. We found that the SFET provides both excellent resolution and high tool activity. This high performance helps us to obtain a clear understanding of the current level of EUVL performance and enables us to learn many things that can be fed back into the development program in the beta stage. A 1st static exposure with the EUV1 resolved 30-nm dense and isolated lines and 30-nm holes. The potential resolution was found to be as good as 28 nm. Although progress was made regarding EUV resist sensitivity and LWR, further progress is needed. A tool for analyzing out-gassing in EUV resists was found to facilitate the development of both resist materials and contamination control measures for exposure tools. A prototype full-field actinic inspection system for mask blanks is now under development and should become operational in the 2Q of 2008. A mask protection engineering (MPE) tool was used to show that a dual-pod carrier is very effective in protecting a mask from particles. Mask pattern defect inspection technology using a DUV wavelength of 199 nm and defect repair technology based on an FIB for EUV mask fabrication are also being developed. This work was supported in part by NEDO.

No abstract

No abstract

No abstract

The capability of an actinic (at-wavelength) inspection system for extreme ultraviolet lithography (EUVL) mask blank has been analyzed by experiment and simulation. The actinic inspection optics, that we developed to obtain a two-dimensional dark field image, consists of illumination optics, Schwarzschild optics with concave and convex mirrors as dark-field imaging optics, and a back-illuminated chargecoupled-device (BI-CCD). A test mask blank with programmed bump defects of smaller sizes and lower heights compared to those used in a previous work was fabricated and the bump defects were detected by the tool. The inspection experiments demonstrated that fabricated multilayer defects down to 1.5 nm in top height and 60 nm in width can be successfully detected. The simulation further indicated that the inspection optics performed well in detecting phase defects of 1.5 nm in height and 40 nm in width.