Multi-layer overlay metrology

Ausschnitt, Christopher P.; Morningstar, Jennifer; Muth, William A.; Schneider, Júlia; Yerdon, R. J.; Binns, Lewis A.; Smith, Nigel

doi:10.1117/12.657397

Cited by 18 publications

(7 citation statements)

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“…As detailed in a previous paper, we believe that Blossom overlay targets offer the precision and scaling required in overlay metrology today. Also, the ability to poll a large number of photolayers at one time is key for efficient overlay control of multi-patterning schemes 4,5,6 . For instance, if one needs to minimize the overlay error of a current via level with respect to multiple metal level exposures, this can easily be done with one snapshot using Blossom.…”

Section: Advanced Overlay Metrologymentioning

confidence: 99%

Overlay improvement roadmap: strategies for scanner control and product disposition for 5-nm overlay

Felix¹,

Gabor²,

Menon³

et al. 2011

SPIE Proceedings

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To keep pace with the overall dimensional shrink in the industry, overlay capability must also shrink proportionally. Unsurprisingly, overlay capability < 10 nm is already required for currently nodes in development, and the need for multi-patterned levels has accelerated the overlay roadmap requirements to the order of 5 nm. To achieve this, many improvements need to be implemented in all aspects of overlay measurement, control, and disposition. Given this difficult task, even improvements involving fractions of a nanometer need to be considered. These contributors can be divided into 5 categories: scanner, process, reticle, metrology, and APC.In terms of overlay metrology, the purpose is two-fold: To measure what the actual overlay error is on wafer, and to provide appropriate APC feedback to reduce overlay error for future incoming hardware. We show that with optimized field selection plan, as well as appropriate within-field sampling, both objectives can be met. For metrology field selection, an optimization algorithm has been employed to proportionately sample fields of different scan direction, as well as proportional spatial placement. In addition, intrafield sampling has been chosen to accurately represent overlay inside each field, rather than just at field corners.Regardless, the industry-wide use of multi-exposure patterning schemes has pushed scanner overlay capabilities to their limits. However, it is now clear that scanner contributions may no longer be the majority component in total overlay performance. The ability to control correctable overlay components is paramount to achieving desired performance. In addition, process (non-scanner) contributions to on-product overlay error need to be aggressively tackled, though we show that there also opportunities available in active scanner alignment schemes, where appropriate scanner alignment metrology and correction can reduce residuals on product. In tandem, all these elements need to be in place to achieve the necessary overlay roadmap capability for current development efforts.

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Section: Advanced Overlay Metrologymentioning

confidence: 99%

Overlay improvement roadmap: strategies for scanner control and product disposition for 5-nm overlay

Felix¹,

Gabor²,

Menon³

et al. 2011

SPIE Proceedings

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“…1D L/S and 2D hole array structures with a composite pattern pitch of 200nm formed by double patterning process as described in figure 1(b) were prepared, and conventional Blossom optical overlay target (5) was selected as a reference metrology system for total measurement uncertainty (TMU) analysis (6) of CD-SEM overlay metrology. The CD-SEM targets used for this analysis are shown in figures 3(a) and 3(b).…”

Section: Tmu Analysis Of Cd-sem Overlay Metrology For 1d and 2d Doublmentioning

confidence: 99%

Concerning the influence of pattern symmetry on CD-SEM local overlay measurements for double patterning of complex shapes

et al. 2010

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We have developed a new local overlay measurement technique on actual device patterns using critical dimension scanning electron microscope (CD-SEM), which can be applied to 2D device structures such as an SRAM contact hole array or more complex shapes. CD-SEM overlay measurement can provide additional local overlay information at the site of device patterns, complementary to the conventional optical overlay data. The methodology includes the use of symmetrically arranged patterns to cancel out many process effects and reduce measurement uncertainty. The developed methodology was applied to local overlay measurement of double patterning contact hole layers of leading edge devices. Local overlay distribution was successfully captured on device structures on different length scale, and the result shows the possibility of assessing process induced shift on device structures and collecting denser sampling for better intra-chip overlay control.The measurement uncertainty of CD-SEM overlay metrology was assessed by comparing with conventional optical overlay metrology for 1D and 2D structures. Very good correlation was confirmed between SEM and optical overlay metrology with net residual error of ~1.1nm. Measurement variation associated with pattern roughness was analyzed for 1D structure, and identified as one of major variation sources for CD-SEM overlay metrology.

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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: 99%

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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Multi-layer overlay metrology

Cited by 18 publications

References 0 publications

Overlay improvement roadmap: strategies for scanner control and product disposition for 5-nm overlay

Overlay improvement roadmap: strategies for scanner control and product disposition for 5-nm overlay

Concerning the influence of pattern symmetry on CD-SEM local overlay measurements for double patterning of complex shapes

Diffraction based overlay metrology for α-carbon applications

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