A study of overlay mark robustness and enhanced alignment techniques for alignment improvement on metal layers of sub-100nm technology

Dubey, Kaushalia; Toru, Nakamura; Tanaka, Hiroshi; Hayashi, Nozomu; Egashira, Shinichi; Mishima, Kazuhiko; Mase, T.; Takeuchi, Tsuyoshi; Honda, Akihiko; Kakizaki, Takatoshi

doi:10.1117/12.711324

Cited by 3 publications

(1 citation statement)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figure 2 shows schematics of typical IBO marks for a photolithography process [1][2][3]. Several overlay alignment marks such as BiB and AIM have been proposed and optimized.…”

Section: Alignment Marksmentioning

confidence: 99%

Inverse optical design using quasi-two-dimensional partially coherent imaging for photolithography overlay metrology

Ohkubo,

Jang,

Lee

et al. 2023

Optical Modeling and Performance Predictions XIII

View full text Add to dashboard Cite

Overlay measurement error is a critical technical issue in the production of highly stacked semiconductor devices, including VNAND memory chips, CMOS image sensors, and three-dimensional packages. Complicated device structure and stacked structure increase the measurement error of overlay alignment mark position. Inverse optical design or system optimization is required to improve overlay metrology accuracy and measurement robustness. Illumination light source wavelength, source bandwidth, illumination mode, and imaging pupil filter can be optimized for overlay metrology signal with various kinds of complicated device structure. We proposed a practical inverse optical solution to improve the accuracy of overlay metrology. The inverse optical design consists of overlay mark reflectance estimation and optical configuration optimization. Both the estimation and optimization are accelerated using a quasi-two-dimensional partially coherent imaging model. We achieve more than 50 times faster imaging simulation acceleration compared to a conventional simulation algorithm for partially coherent illumination imaging with practical accuracy. Further improvement can be realized with an introduce of an overlay mark reflectance matrix computed by a rigorous electromagnetic analysis simulation for each specific device structure. This robust and practical inverse solution can help improve the overlay accuracy and manufacturing yield of highly complex three-dimensional devices.

show abstract

“…Figure 2 shows schematics of typical IBO marks for a photolithography process [1][2][3]. Several overlay alignment marks such as BiB and AIM have been proposed and optimized.…”

Section: Alignment Marksmentioning

confidence: 99%

Inverse optical design using quasi-two-dimensional partially coherent imaging for photolithography overlay metrology

Ohkubo,

Jang,

Lee

et al. 2023

Optical Modeling and Performance Predictions XIII

View full text Add to dashboard Cite

show abstract

Signal Processing Using Karhunen–Loève Expansion for Wafer Focus Measurement in Lithography

Oishi

Ina

Miyashita

2011

Jpn. J. Appl. Phys.

View full text Add to dashboard Cite

We propose a new signal processing method using Karhunen–Loève (KL) expansion for wafer focus measurement in lithography. With the improvement in the critical dimension (CD) accuracy, more high accuracy of wafer focus measurement becomes to be necessary. Recently, it is said that focus accuracy should be required within several ten nanometers. The accuracy of the focus measurement of the actual process wafer does not meet the requirement values due to the complexity of its structure. The objective of this study is the improvement of the focus accuracy for the actual process wafers. Our proposing focus signal processing has two steps. The first step is a supervised learning step in which main component signal waveforms (basis functions) are obtained by using KL expansion from many focus signals whose center positions are known in advance. The second step is a center position detecting step in which an input signal is approximated by using the basis functions obtained in the learning step and the center position of the signal is detected. From a comparison between the conventional signal processing and the proposing signal processing, we obtained the following result to simulated signal. Focus accuracy was rapidly improved (97%) when three basis functions were used for the approximation. By using this technology, the focus detection system can be achieved with a high accuracy and robust against various process wafers.

show abstract

Signal Processing Using Karhunen–Loève Expansion for Wafer Focus Measurement in Lithography

Oishi¹,

Ina²,

Miyashita³

2011

Jpn. J. Appl. Phys.

View full text Add to dashboard Cite

A study of overlay mark robustness and enhanced alignment techniques for alignment improvement on metal layers of sub-100nm technology

Cited by 3 publications

References 0 publications

Inverse optical design using quasi-two-dimensional partially coherent imaging for photolithography overlay metrology

Inverse optical design using quasi-two-dimensional partially coherent imaging for photolithography overlay metrology

Signal Processing Using Karhunen–Loève Expansion for Wafer Focus Measurement in Lithography

Signal Processing Using Karhunen–Loève Expansion for Wafer Focus Measurement in Lithography

Contact Info

Product

Resources

About