In order to achieve stable operation in cutting-edge semiconductor manufacturing, Nikon has developed NSR-S630D with extremely accurate overlay while maintaining throughput in various conditions resembling a real production environment. In addition, NSR-S630D has been equipped with enhanced capabilities to maintain long-term overlay stability and user interface improvement all due to our newly developed application software platform. In this paper, we describe the most recent S630D performance in various conditions similar to real productions. In a production environment, superior overlay accuracy with high dose conditions and high throughput are often required; therefore, we have performed several experiments with high dose conditions to demonstrate NSR’s thermal aberration capabilities in order to achieve world class overlay performance. Furthermore, we will introduce our new software that enables long term overlay performance.
Nikon’s new immersion scanner “NSR-S630D” has been developed to deliver enhanced product overlay and CD
uniformity while improving productivity at 10 nm half pitch node and beyond. The NSR-S630D is equipped with
various advanced technologies. Among them are the new reticle stage with encoder servo control and advanced reticle
bending mechanism, new optics with enhanced correction knobs for thermal aberration control, and advanced thermally
stable wafer stage; all of which are key components to providing the best scanner solution to meet the requirements for
10 nm half pitch node and beyond.
In this paper, we describe the NSR-630D development concept and the latest performance data at factory. One of the key
factors in improving overlay is shot distortion; in order to improve shot distortion, the NSR-S630D is equipped with a
newly developed state-of-the-art projection lens. The overall overlay improvements have been made possible not only by
minimizing lens distortion through advancements in lens manufacturing techniques, but also by reducing thermal
distortion, which is especially important in actual device production. In addition, we have also added a new function for
more effective reticle heating distortion compensation. In order to improve wafer grid performance, we newly designed a
wafer table with enhanced thermal stability. We have also further improved the reticle bending system in order to
minimize the field curvature induced by projection lens thermal aberration. The new features described above, in
addition to the matured Streamlign platform, have enabled the NSR-S630D to deliver highest accuracy and stability.
NSR-S622D, Nikon’s new ArF immersion scanner, provides the best and practicable solutions to meet the escalating requirement from device manufactures to accommodate the further miniaturization of device pattern. NSR-S622D has various additional functions compared to the previous model such as the newly developed illumination system, new projection lens, new AF system new wafer table in addition to the matured Streamlign platform. These new features will derive the outstanding performance of NSR, enabling highly controlled CD uniformity, focus accuracy and overlay accuracy. NSR-S622D will provide the adequate capabilities that are demanded from a lithography tool for production of 1x nm hp node and beyond.
Double patterning (DP) is widely regarded as the lithography solution for 32 nm half pitch semiconductor manufacturing,
and DP will be the most likely litho technology for the 22 nm node . When using the DP technique, overlay accuracy
and CD control are of critical importance . We previously introduced the NSR-S620D immersion scanner, which
provides 2 nm overlay capabilities. In the case of the latest generation NSR-S621D system, improvements have been
developed for further overlay accuracy enhancement.
In this paper, we will show the overlay accuracy and Mix-and-Match performance of the NSR-S621D. Further, the
marked improvement in product overlay and the overlay result in Spacer DP as a result of enhanced alignment accuracy
will also be shown.
To achieve the 2 nm overlay accuracy required for double patterning, we have introduced the NSR-S620D immersion
scanner that employs an encoder metrology system. The key challenges for an encoder metrology system include its
stability as well as the methods of calibration. The S620D has a hybrid metrology system consisting of encoders and
interferometers, in XY and Z. The advantage of a hybrid metrology system is that we can continuously monitor the
position of the stage using both encoders and interferometers for optimal positioning control, without any additional
metrology requirements or throughput loss. To support this technology, the S620D has various encoder calibration
functions that make and maintain the ideal grid, and control focus. In this paper we will introduce some of the encoder
calibration functions based on the interferometer. We also provide the latest performance of the tool, with an emphasis
on overlay and focus control, validating that the NSR-S620D delivers the necessary levels of accuracy and stability for
the production phase of double patterning.
Double patterning (DP) has become the most likely candidate to extend immersion lithography to the 32 nm node and
beyond. This paper focuses on experimental results of 32nm half pitch patterning using NSR-S620D, the latest Nikon
ArF immersion scanner. A litho-freeze-litho (LFL) process was employed for this experiment. Experimental results of
line CDU, space CDU, and overlay accuracy are presented. Finally, a budget for pitch splitting DP at the 22 nm half
pitch is presented.
Double patterning requires extremely high accuracy in overlay and high uniformity in CD control. For the 32 nm half
pitch, the CDU budget requires less than 2 nm overlay and less than 2 nm CD uniformity for the exposure tool. To meet
these requirements, Nikon has developed the NSR-S620D. It includes a new encoder metrology system for precise stage
position measurement. The encoder system provides better repeatability by using a short range optical path. For CD
uniformity control, various factors such as focus control, stage control, and dose control affect the results. Focus
uniformity is evaluated using the phase shift focus monitoring method. The function of "CDU Master" provides dose and
focus correction across the exposure slit, along the scan direction, and across the wafer. Stage synchronization variability
will also influence CD control. In this paper, we will show the actual results and analysis of the overall performance of
S620D, including the exposed result of pitch splitting double patterning. S620D has sufficient performance for the 32 nm
half pitch double patterning generation and shows potential for double patterning at the 22 nm half pitch node.