Feed-forward alignment correction for advanced overlay process control using a standalone alignment station "Litho Booster"

Yahiro, Takehisa; Sawamura, Junpei; Dosho, Tomonori; Shiba, Yuji; Ando, Satoshi; Ishikawa, Jun; Morita, Masahiro; Shibazaki, Yuichi

doi:10.1117/12.2297300

Cited by 4 publications

(6 citation statements)

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“…In addition, if the distortion of the underlayer is already known before data conversion, it is possible to deform the pattern before the conversion for better overlay adjustment. There is a high-speed alignment station that can measure alignment map of the underlayer with dense sampling and feed-forward the measured map to exposure tools before exposure 10 . The throughput of the alignment station depends on the number of sampling points on a wafer.…”

Section: Ds Systemmentioning

confidence: 99%

Section: Application Area Of Dsmentioning

confidence: 99%

“…There is a high-speed alignment station that can measure alignment map of the underlayer with dense sampling and feed-forward the measured map to exposure tools before exposure. 10 The throughput of the alignment station depends on the number of sampling points on a wafer. The throughput of 114 wafers per hour (wph) can be obtained with sampling points of 437 on a 300 mm wafer as an example.…”

Section: Overlaymentioning

confidence: 99%

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Development of deep ultraviolet optical maskless exposure tool for advanced lithography

Watanabe

Kanaya

Saito

et al. 2023

J. Micro/Nanopattern. Mats. Metro.

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Digital scanner (DS), a deep ultraviolet optical maskless exposure tool is being developed. DS uses a micromirror-type spatial light modulator to create the "mask" pattern combined with a solid-state laser with a wavelength of 193 or 248 nm. The exposure concept of DS and advantage of solid-state laser as an exposure light source is described. DS proof-of-concept tool with resolution of half-pitch 80 nm L/S was developed. The exposure results of maskless unique application, such as large area printing and chip ID printing for security purposes, are shown.

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Section: Ds Systemmentioning

confidence: 99%

Section: Application Area Of Dsmentioning

confidence: 99%

Section: Overlaymentioning

confidence: 99%

See 1 more Smart Citation

Development of deep ultraviolet optical maskless exposure tool for advanced lithography

Watanabe

Kanaya

Saito

et al. 2023

J. Micro/Nanopattern. Mats. Metro.

View full text Add to dashboard Cite

show abstract

“…This can be a time-consuming experimental process that requires actual product and negatively impacts the scanner and metrology tools' availability. To simplify the evaluation procedure, we provide an overlay run-to-run simulation method in our software suite, OVALiS [3]. As shown in Figure 1-1, by removing the old corrections from the original alignment and overlay strategies, and then applying new corrections from the new alignment and overlay strategies, the overlay performance of the target layer can be readily predicted.…”

Section: Introductionmentioning

confidence: 99%

Advanced cross-layer overlay simulation with exposure grid re-calculation

Lu,

Tsou,

Demirer

et al. 2024

Metrology, Inspection, and Process Control XXXVIII

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In today's advanced semiconductor industry with the multitude of new products and device requirements, lithography process changes are inevitable and expected due to tighter overlay specifications and the increasing influence of process effects. To minimize the overlay impact from the wafer-to-wafer and lot-to-lot variation, lithography engineers often need to adjust wafer alignment and overlay strategies to optimize product yield. Overlay simulation methods are often used to estimate if new alignment and/or overlay strategies can help achieve better overlay performance. By removing the old corrections from the original alignment and overlay data, and then applying new corrections, the overlay performance can be readily predicted, saving significant time. However, available software suites only simulate the current layer overlay. Overlay risks would therefore remain on subsequent layers without an effective simulation method to predict the impact resulting from changes to the alignment and/or overlay strategies on the current layer.In our study, we demonstrate a new method to simulate the overlay performance on the subsequent layers by re-calculating the current layer exposure grid. Our dataset has 3 layers: L0, L1, and L2. On L1 (current layer), we apply a new alignment model and overlay control strategy with a feedforward solution. Then, we re-calculate the exposure grid to generate a new (virtual) alignment and overlay dataset for L2 (following layer). Finally, we estimate the overlay impact on L2 with the new alignment and overlay dataset and summarize the benefits of this new cross-layer overlay simulation method.

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“…The overlay error is controlled based on the overlay measurement before and after the lithography process. The former control is feedforward control referenced by the measurement of TWINSCAN system or standalone system [1]. The latter control is feedback control referenced by measurement of standalone system to trace the real-time drift of overlay error.…”

Section: Introductionmentioning

confidence: 99%

Exploiting spatial characteristic of wafer for effective OCW: area partitioning OCW

Song

Kang

Kim

et al. 2023

Metrology, Inspection, and Process Control XXXVII

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Optimal color weighting (OCW) is a promising technique to improve accuracy and robustness of alignment mark measurement in the lithography process. Measurement based OCW shows remarkable improvement of overlay error under laboratory conditions. In those conditions, one of the wafer processes is split and a simple form of mark deformation is present. However, the OCW effect has not been confirmed in the case of on-product overlay since various of deformations are mixed in the real FAB. We perform simple simulation showing that mixed deformations can deteriorate the performance of OCW and show that utilizing spatial characteristics of the wafer with OCW further improves the overlay error. As a result, we have improved on-product-overlay form 3.78 nm to 3.51 nm or 7.1% using data of 86 lots, 268 wafers in DUV layer of 3 nm logic device.

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Feed-forward alignment correction for advanced overlay process control using a standalone alignment station "Litho Booster"

Cited by 4 publications

References 0 publications

Development of deep ultraviolet optical maskless exposure tool for advanced lithography

Development of deep ultraviolet optical maskless exposure tool for advanced lithography

Advanced cross-layer overlay simulation with exposure grid re-calculation

Exploiting spatial characteristic of wafer for effective OCW: area partitioning OCW

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