Motokatsu Imai

An improved virtual aberration model to simulate mask 3D and resist effects

As shrinkage of design features progresses, the difference in best focus positions among different patterns is becoming a fatal issue, especially when many patterns co-exist in a layer. The problem arises from three major factors: aberrations of projection optics, mask 3D topography effects, and resist thickness effects. Aberrations in projection optics have already been thoroughly investigated, but mask 3D topography effects and resist thickness effects are still under study. It is well known that mask 3D topography effects can be simulated by various Electro-magnetic Field (EMF) analysis methods. However, it is almost impossible to use them for full chip modeling because all of these methods are extremely computationally intensive. Consequently, they usually apply only to a limited range of mask patterns which are about tens of square micro meters in area. Resist thickness effects on best focus positions are rarely treated as a topic of lithography investigations. Resist 3D effects are treated mostly for resist profile prediction, which also requires an intensive EMF analysis when one needs to predict it accurately. In this paper, we present a simplified Virtual Aberration (VA) model to simulate both mask 3D induced effects and resist thickness effects. A conventional simulator, when applied with this simplified method, can factor in both mask 3D topography effects and resist thickness effects. Thus it can be used to model inter-pattern Best Focus Difference (BFD) issues with the least amount of rigorous EMF analysis.

An immersion scanner enabling 10 nm half pitch production and high productivity

Nikons newly developed immersion scanner, NSR-S630D, provides exceptional performance in product overlay, CD uniformity, and productivity at 10 nm hp node and beyond. Generally, maintaining machine accuracy and productivity at a high level is difficult because they are in a trade-off relationship. The NSR-S630D is equipped with new features including an encoder servo-controlled reticle stage, reticle bending mechanism, optics with enhanced thermal aberration control, and thermally stable wafer stage. These features enable the NSR-S630D to deliver highest accuracy and productivity.

A simple method of source optimization for advanced NAND FLASH process

We have developed a very simple source optimization (SO) method for L/S and C/H critical layers patterning of advanced NAND FLASH. Starting from the strong off-axis illumination shape which is optimized for the finest structure of the mask pattern, a systematic procedure is performed to extract the optimum parameters of additional assist sources to balance the imaging performance (DOF, contrast and optical proximity effect, etc.) of dense/sparse/rough patterns. Performance equations (linear optimization) with performance map (sensitivity) are utilized to search the best combination of intensity for each assist source. For C/H pattern, the optimization procedure is modified to solve the non-linearity and non-continuity problems on the relationship between assist source intensity and each imaging performance. Finally, optimized source shapes have been successfully demonstrated and verified on 40 nm node NAND FLASH L/S and C/H critical patterns despite the simplicity of the optimization method, without utilizing SO dedicated software.

High Performance Technology in Components for Linear Drive Systems. High Performance Technology in Absolute Encoder.

直動システムのアブソリュートエソコーダとして現在開発中のバックアップ不要で自己診断機能付きのアブソリュートスケールを中心に述べた.従来のバックアップスケールに対し外部電池が不要という利点,絶対位置データの比較確認が可能であるほかに,瞬間の速度超過で位置を見失った場合も速度が下がり次第,正確な絶対位置を求めることも可能である.今後の課題は高精度な内挿技術により,M系列パターンとインクリメンタルパターン各1本だけで構成し,安価なアブソリュートスケールを開発することである.

36000000 Pulses Absolute Encoder.

This paper describes the method of detecting the absolute position by four track : the 5 625 pulses absolute track, its the inverse track, the 5 625 pulses incremental track and 45 000 pulses incremental track, and of doing 2 bit error detection and 1 bit error correction of the 5 625 pulses absolute positions. The 5 625 pulses absolute tracks are made by the selected partof the 8 191 length M-sequences. The 11 200, 22 500 pulses signals for detecting the 45 000 absolute position, are made by interporating of the 5 625 pulses incremental signal. The 45 000 pulses absolute positions are gotten by adjusting the phase relation between the interporated signals and the 45 000 pulses incremental signal. The 36 000 000 pulses absolute positions are gotten by interporating the 45 000 pulses incremental signal. The 2 bit error detections and 1 bit error correction are done by the linear reflexive relations of a M-sequences and look-up table of the ROM (Read Only Memory).