Blossom overlay metrology implementation

Ausschnitt, Christopher P.; Chu, W. H.; Kolor, D.; Morillo, Jaime; Morningstar, Jennifer; Muth, William A.; Thomison, C.; Yerdon, R. J.; Binns, Lewis A.; Dasari, Prasad; Fink, Hans‐Werner; Smith, Nigel; Ananew, G.

doi:10.1117/12.712669

Cited by 13 publications

(5 citation statements)

References 0 publications

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“…The blossom key in Fig. 3 has the feature [5][6][7] of being able to measure the overlay of multiple layers simultaneously with a single target, and the Auros key has the feature of being able to minimize the aberration error.…”

Section: Conventional Overlay Target Designmentioning

confidence: 99%

“…For this reason, a modified form is used instead of using the grid pattern as it is. [5][6][7] Figure 9 is an overlay target designed to suppress cross-interference, and it is designed by filling in the intersecting points with blanks to eliminate cross-interference. The design of inserting an intersection pattern on another floor like the GI key is an improvement that puts an intersection pattern on the same floor as the blossom key.…”

Section: Grating Intersection (Gi) Keymentioning

confidence: 99%

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Image-based overlay target design using a grating intersection

Lee¹,

Chang²,

Shin³

et al. 2022

J. Micro/Nanopattern. Mats. Metro.

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Background: An overlay target design is essential before performing overlay metrology and has a great impact on overlay performance. In addition, accurate overlay metrology is required to achieve high product yields in semiconductor manufacturing. When asymmetry of the overlay target occurs, it is necessary to increase the area of the pattern existing in the target and stabilize the optical aberration for stable measurement. For this reason, we propose an image-based overlay target design that can secure a larger area compared with the existing overlay target and stabilize the optical aberration by overlapping and exposing the upper and lower patterns of the overlay target.Aim: The effective area of the existing mark design is improved by proposing an overlay target and a measurement method used in image-based overlay measurement.Approach: The proposed overlay target design is configured by arranging different marks orthogonally to the upper and lower layers, and different two-dimensional information can be inserted in the same area. When necessary, single-dimensional information desired by the user can be obtained through a technique called projection, and it has the advantage of using a larger effective area than the existing overlay target.Results: Overlay can be measured using projected signal components, and the possibility and performance of the proposed target can be confirmed through simulation and test wafer. In addition, it was possible to bring about a 15% improvement in total measurement uncertainty performance compared with the existing advanced imaging metrology (AIM) target by taking a wider effective area.Conclusions: An overlay target design is proposed to solve the technical problems of the existing overlay target design. The proposed overlay target has a method that is capable of minimizing the size of the overlay target while maximally maintaining the signal density, a way of reducing the influence of aberration, and various other advantages.In addition, the proposed method provides a design rule that breaks the "lower pattern and upper pattern must not overlap" framework.

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Section: Conventional Overlay Target Designmentioning

confidence: 99%

Section: Grating Intersection (Gi) Keymentioning

confidence: 99%

Image-based overlay target design using a grating intersection

Lee¹,

Chang²,

Shin³

et al. 2022

J. Micro/Nanopattern. Mats. Metro.

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“…Repeatability for overlay measurement is improved by higher resolution imaging (smaller pixel size or larger frame number) and by increasing the number of measurement points (edge length). 49,50 The relationship between repeatability and throughput should be taken into account when SEM-OL is considered as an alternative for Opt-OL measurements. Figure 7 shows CD-SEM imaging for SRAM pattern after DD etching.…”

Section: Dedicated Mark and Algorithm Of Sem-ol Metrologymentioning

confidence: 99%

Review of scanning electron microscope-based overlay measurement beyond 3-nm node device

Ito

Hasumi

2019

J. Micro/Nanolith. MEMS MOEMS

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Overlay control has been one of the most critical issues for manufacturing of leading edge semiconductor devices. Introduction of the double patterning process requires stringent overlay control. Conventional optical overlay (Opt-OL) metrology has technical challenges with measurement robustness, solving overlay discrepancy between overlay mark and device pattern, and measuring smaller marks laid out in large numbers within the die accurately for high-order correction. In contrast, scanning electron microscope-based overlay (SEM-OL) metrology can directly measure both overlay targets and actual devices or device-like structures on processed wafers with high spatial resolution. It can be used for reference metrology and optimization of Opt-OL measurement conditions. SEM-OL uses small structures, including actual device patterns, which allows insertion of many SEM-OL targets across a die. Precise overlay distribution can be measured using dedicated SEM-OL mark, improving measurement accuracy and repeatability. To extend SEM-OL capability, we have been developing SEM-OL techniques that can measure not only surface patterns by critical dimension SEM but also buried patterns for leading edge device processes. There are two techniques to detect buried patterns. One is to use high-acceleration voltage SEM, which detects backscattering electron emphasizing material contrast. It has been adopted for overlay measurements for memory and logic devices at after-etch inspection or even after-develop inspection. The other is to utilize charging effect, which reflects voltage contrast at the surface depending on the material properties of underneath structure. SEM-OL measurement using transient voltage contrast has been developed and its capability of overlay measurement has been proven. An overlay measurement algorithm using template matching method has been developed and was applied to dynamic random access memory (DRAM) process monitor in manufacturing. In order to extend SEM-OL metrology to beyond 3-nm node logic and cutting-edge DRAM devices (half pitch = 14 nm), we are improving measurement precision of detecting buried patterns and measurement throughput by developing optimized SEM-OL mark.

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“…Since the transparency of ACL films improve with increasing wavelengths (Figure 1), imaging using near IR wavelengths has considerably helped improvement in performance. This performance can be expected to improve with high precision targets such as Blossom [4,5]. However, sub-nm measurement uncertainties in tool performance still remain a significant challenge.…”

Section: Introductionmentioning

confidence: 98%

Diffraction based overlay metrology for α-carbon applications

Saravanan¹,

Tan²,

Dasari³

et al. 2008

SPIE Proceedings

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Applications that require overlay measurement between layers separated by absorbing interlayer films (such as α-carbon) pose significant challenges for sub-50nm processes. In this paper scatterometry methods are investigated as an alternative to meet these stringent overlay metrology requirements. In this article, a spectroscopic Diffraction Based Overlay (DBO) measurement technique is used where registration errors are extracted from specially designed diffraction targets. DBO measurements are performed on detailed set of wafers with varying α-carbon (ACL) thicknesses. The correlation in overlay values between wafers with varying ACL thicknesses will be discussed. The total measurement uncertainty (TMU) requirements for these layers are discussed and the DBO TMU results from sub-50nm samples are reviewed. Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/28/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx Proc. of SPIE Vol. 6922 69222W-3 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/28/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx Proc. of SPIE Vol. 6922 69222W-11 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/28/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx

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Blossom overlay metrology implementation

Cited by 13 publications

References 0 publications

Image-based overlay target design using a grating intersection

Image-based overlay target design using a grating intersection

Review of scanning electron microscope-based overlay measurement beyond 3-nm node device

Diffraction based overlay metrology for α-carbon applications

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