Characterization of 32nm node BEOL grating structures using scatterometry

Zangooie, S.; Sendelbach, Matthew; Angyal, M.; Archie, Charles N.; Vaid, Alok; Matthew, Itty; Herrera, Pedro

doi:10.1117/12.773088

Cited by 10 publications

(6 citation statements)

References 6 publications

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“…Typically, BEOL OCD developments are reported for wafers with short-loop processing only, i.e., no FEOL or MOL content is present. [22][23][24][25][26] Transferring these learnings to manufacturing is not straightforward because of the aforementioned challenges. Timoney et al discussed the substantial modeling complexities for M2 on fully integrated targets at the 7-and 14-nm nodes.…”

Section: Scatterometry Challenges and Strategiesmentioning

confidence: 99%

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Spectral interferometry for fully integrated device metrology

Schmidt¹,

Medikonda²,

Rizzolo³

et al. 2023

J. Micro/Nanopattern. Mats. Metro.

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A spectral interferometry technique called vertical travelling scatterometry (VTS) is introduced, demonstrated, and discussed. VTS utilizes unique information from spectral interferometry and enables solutions for applications that are infeasible with traditional scatterometry approaches. The technique allows for data filtering related to spectral information from buried layers, which can then be ignored in the optical model. Therefore, using VTS, selective analyses of the topmost part of an arbitrarily complex stack are possible within a single metrology step. This methodology helps to overcome geometrical complexities and allows for focusing on parameters of interest through dramatically simplified optical modeling. Such model simplifications are specifically desired for back-end-of-line applications. Three examples are monitored discussed: (i) the critical dimensions (CDs) of a first metal level on top of nanosheet gate-all-around transistor structures, (ii) the thickness of an interlayer dielectric above embedded memory in the active area, and (iii) the CDs of trenches on top of tall stacks in the micrometer range comprising many layered dielectrics. It was found that, in all three cases, data filtering through VTS allowed for a simple optical model capable of delivering parameters of interest. The validity and accuracy of the VTS solution results were confirmed by extensive reference metrology obtained by traditional scatterometry, scanning electron microscopy, and transmission electron microscopy. Furthermore, it was shown that machine learning models trained with VTS filtered data can converge to a robust solution with a smaller dataset compared with models training with traditional scatterometry data.

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Section: Scatterometry Challenges and Strategiesmentioning

confidence: 99%

“…Typically, BEOL OCD developments are reported for wafers with short-loop processing only, i.e., no FEOL or MOL content is present 22 – 26 Transferring these learnings to manufacturing is not straightforward because of the aforementioned challenges. Timoney et al.…”

Section: Scatterometry Challenges and Strategiesmentioning

confidence: 99%

Spectral interferometry for fully integrated device metrology

Schmidt¹,

Medikonda²,

Rizzolo³

et al. 2023

J. Micro/Nanopattern. Mats. Metro.

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show abstract

“…Here, SiNCH, ULK, HM and OPL stand for nitrogen doped SiC, ultra low k, hard mask, and optical planarization layer, respectively. 3 The critical parameters for this application are the bottom critical dimension (BCD) of the resist, middle CD (MCD) of the resist, sidewall angle (SWA) of the resist, and height of the resist. For this work two wafers were measured, one exposed with a focus-exposure matrix (FEM), the other exposed with constant and standard (POR) lithography conditions.…”

Section: Beol M2 Post-lithomentioning

confidence: 99%

Use of multiple azimuthal angles to enable advanced scatterometry applications

et al. 2010

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The ability to extract critical parameters using scatterometry depends on the parameter sensitivity and correlation at different wavelengths. These, in turn, determine the key metrics: accuracy, precision, and tool-to-tool matching. Parameter sensitivity and correlation can vary drastically, depending on whether the oblique incident light beam is parallel (azimuth angle = 90 degrees), perpendicular (azimuth angle = 0 degrees), or at an intermediate angle to the measured structures. In this paper, we explore the use of both variable-and multiple-azimuth (AZ) (or multi-AZ) angle spectroscopic ellipsometry (SE) to optimize the measurement performance for different applications.The first example compares the sensitivity and results using SE at 0 and 90 degree AZ angles for a BEOL post-litho metal trench application. We observe up to a sixfold improvement in key metrics for critical parameters using 90 degree over 0 degree AZ angle spectra.The second example illustrates the benefits of a multiple-AZ angle approach to extract critical parameters for a twodimensional logic High-K Metal Gate (HKMG) structure. Typically, this approach simultaneously fits two sets of SE spectra collected from the same location on the wafer at different AZ angles with the same physical model. This helps both validate and decorrelate critical parameters, enabling robust measurements. Results show that, for this application, the measurement performance metrics for each critical parameter are improved in almost every case.

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“…Ideally, the user would be able to float all of the parameters in the model. This was possible for some simpler devices used in previous nodes; however, as device complexity increases [2,3,4], the number of layers and number of gratings (as in double patterning lithography (DPL)) increases. This increased complexity forces the user to make compromises during model optimization.…”

Section: Introductionmentioning

confidence: 98%

Improved scatterometry time to solution for leading-edge logic applications

Vaid

Sendelbach

Komarov³

et al. 2010

2010 IEEE/SEMI Advanced Semiconductor Manufacturing Conference (ASMC)

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This paper describes an innovative approach to scatterometry modeling, significantly reducing time to solution compared to the industry's current best practices. One of the drawbacks to traditional scatterometry measurement techniques is the time required to optimize the model, which includes material optical constant extraction, model build time, initial model optimization, and model testing. A novel methodology that includes both stability and self-consistent scatterometry accuracy prediction can achieve an order of magnitude gain in productivity over prior methods. This technique creates opportunities among semiconductor chip manufacturers for wider scatterometry adoption at advanced technology nodes, where scatterometry is often the only reliable non-destructive metrology for device structure dimensions. The reductions in cycle time and improvements in accuracy prediction are keys to the success of scatterometry as an enabler for advanced process control and monitoring. This paper presents results on a conventional poly gate litho and final inspection and on leading-edge high-k metal gate after-etch applications. Spectroscopic ellipsometry is used to collect spectra from the gratings on the wafers. Then scatterometry results are obtained using the new approach and via traditional industryaccepted procedures to compare time to solution. To confirm the validity of the results, reference metrology data are collected on a CDSEM and TEM and the total measurement uncertainty is evaluated.

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Characterization of 32nm node BEOL grating structures using scatterometry

Cited by 10 publications

References 6 publications

Spectral interferometry for fully integrated device metrology

Spectral interferometry for fully integrated device metrology

Use of multiple azimuthal angles to enable advanced scatterometry applications

Improved scatterometry time to solution for leading-edge logic applications

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