Nobuyuki Yoshioka

Performance of novel 198.5-nm wavelength mask inspection system for 65-nm node and beyond optical lithography era

In 65nm node and some more technology node probably may go with current optical lithography and industry has predicted many challenges. In patterning point of view, quality and cost of mask became more and more important than ever. Particularly, mask defect engineering technology is key area not only inspect the defects but also mask process monitoring and improvements. In mask inspection technology there were a lot of new progresses to enhance the defect inspection sensitivity and stability. The key solution to achieve better sensitivity may be short inspection wavelength and adequate detection algorithm. In this paper, we will propose defect size specifications of 65nm and beyond optical mask with various OPC and RET environments. In addition, we will present initial data of newly developed 198.5nm inspection wavelength system. Through this study, we found future optical mask faces new challenges in defect inspection and to solve these problems, we need advanced mask inspection system and collaborations among patterning related fields.

Advanced mask inspection optical system (AMOS) using 198.5-nm wavelength for 65-nm (hp) node and beyond: system development and initial state D/D inspection performance

A novel high-resolution mask inspection platform using DUV wavelength has been developed. This platform is designed to enable the defect inspection of high quality masks for 65nm node used in 193nm lithography. In this paper, newly developed optical system and its performance are reported. The system is operated at wavelength of 198.5nm, which wavelength is nearly equal to 193nm-ArF laser exposure tool. Some defect image data and defect inspection sensitivity due to simulation-base die-to-die (D/D) inspection are shown on standard programmed defect test mask. As an initial state D/D inspection performance, 20-60 nm defects are certified. System capabilities for 65nm node inspection and beyond are also discussed.

Inspection capability of high-transmittance HTPSM and OPC masks for ArF lithography

We have improved DUV laser reticle inspection system LM7000 for 90 nm technology node devices. To increase inspection sensitivity, we developed a reflected light inspection as a supplementary method to transmittance light inspection. We have also strengthened inspection algorithm to distinguish between real defects and very small features from optical proximity effect correction (OPC). Finally, we have improved reference image for die to database inspection. With the merit of short wavelength of LM7000 (266 nm), the inspection sensitivity of the high-transmittance half-tone phase shift mask (HTPSM) does not deteriorated so severely compared to that of binary mask. With the help of these series of improvements, LM7000 could shows inspection capability for OPC masks and HTPSM for ArF lithography. The inspection capability of LM7000 was proved with the programmed defect masks and printability experiment using ArF scanner.

Mask Inspection Technology for 65nm (hp) Technology Node and Beyond

The application of the high numerical aperture, 193nm‐ArF laser exposure system is expected to be extended to 65nm node device production and beyond. The extension of 193nm lithography means that the pattern transfer using this exposure system is done under lower k1 condition than previously. This leads to the increase of mask error enhancement factor (MEEF) in the exposure process. Since mask critical dimension (CD) uniformity and defects on a mask are more difficult to control, defect detection consistency with lithography wavelength for the mask inspection system is strongly required. A novel high‐resolution mask inspection platform is developed to enable the high‐quality mask defect inspection for 65–45nm node. The system is operated at wavelength of 198.5nm, which wavelength is nearly equal to that of the 193nm‐ArF laser exposure system. The defect detection performance of 20–60nm defect detection sensitivity is certified at the early stage test. The system capabilities for 65nm node inspection and b...

Optical mask inspection strategy for 65-nm node and beyond

As semiconductor integration goes down to nano-meter scale, finer patterning technology is inevitable. Therefore it is more and more important not only new lithographic development but also mask quality enhancement. Particularly, due to the delay of NGL technology, optical lithography is growing candidate for 65nm and beyond node device. In that case, mask CD uniformity and defect control issues are more important than ever. In mask inspection technology, there were a lot of new progresses to enhance the defect inspection sensitivity and stability via short-wavelength and advanced defect inspection algorithms. In this paper, we will present a concept and on going status of newly developed short-wavelength DUV inspection tool that is co-worked by Selete, Toshiba, and NEC. Moreover, we will discuss defect specifications that is required 65nm node and beyond technology node by simulations. This will include relations between defect inspectability and printability in the case of ArF, ArF immersion, and F2 lithography in various layouts and patterns. Through this study, we can conclude stable short-wavelength inspection tool and proper inspection algorithms are essential for future generation mask to cope with low k1 lithography.

Advanced Mask Inspection and Metrology

Lithography is one of the most important semiconductor micro‐fabrication technologies that form mask pattern images onto the substrate. Since a mask is the original edition of semiconductor patterns, precise control of the mask aperture size becomes critical. The masks have to be made up in the accurately controlled patterns and zero defects. Therefore, mask inspection and metrology that guarantee the mask qualities are important key technologies for realizing the semiconductor production with high reliability and high yield. The advanced inspection and metrology are being developed. The requirements, technical issues, and current status of these technologies are reported. Mask inspection technologies for next generation lithography such as electron projection lithography (EPL) and extreme ultraviolet lithography (EUVL) are also reported.

DUV inspection capability for 90-nm node mask in ArF lithography

As the ArF lithography technology is going to progress to 90nm node from 130nm node, it has been more difficult to inspect all types of mask defects, which influence wafer. Photomask for 90nm node, the aggressive OPC mask and Phase Shift Mask (PSM) might be inevitable in production devices due to the slow progresses in lithography equipment itself compared to shrinkage speed in device manufacturing. Recently, due to the similiar effect such like MEEF (Mask Error Enhancement Factor) phenomenon many mask defects become to detect difficult even printable defects even the lots of improvements mask inspection equipments. In this paper, we will present the inspection capability of advanced DUV inspection tool LM7000 (NEC) with various programmed defect masks (e.g. aggressive OPC masks, half-tone PSM, tri-tone PSM) with, and discuss the relationship between inspection sensitivity and mask defect printability.