Gaps analysis for CD metrology beyond the 22nm node

Bunday, Benjamin; Germer, Thomas A.; Vartanian, Victor; Cordes, Aaron; Cepler, Aron; Settens, Charles

doi:10.1117/12.2012472

Cited by 57 publications

(40 citation statements)

References 49 publications

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“…Measurement sensitivity of less than 0.1 nm was revealed for sub-25 nm wide lines (critical dimensions (CDs)) again using 546 nm wavelength [8]. TSOM is being increasingly recognized as a viable nanometrology method, as evidenced by being listed in several technology roadmaps and guides [19–21], patent applications [22,23], and science news reports [24,25]. …”

mentioning

confidence: 99%

Noise analysis for through-focus scanning optical microscopy

Attota¹

2016

Opt. Lett.

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A systematic noise-analysis study for optimizing data collection and data processing parameters for through-focus scanning optical microscopy (TSOM) is presented. TSOM is a three-dimensional shape metrology method that can achieve sub-nanometer measurement sensitivity by analyzing sets of images acquired through-focus using a conventional optical microscope. We show that best balance between signal-to-noise performance and acquisition time can be achieved by judicious spatial averaging. Correct background-signal subtraction of the imaging-system inhomogeneities is also critical, as well as careful alignment of the constituent images in the case of differential TSOM analysis.

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confidence: 99%

Noise analysis for through-focus scanning optical microscopy

Attota¹

2016

Opt. Lett.

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“…Therefore, variations in these parameters were studied for the parameter ranges shown in Table 1. Following industry requirements, trenches in Si and trenches and holes in oxide were studied [3]. The results for the 11 nm and 32 nm DR trench and hole structures are shown in Figs.…”

Section: Tsom For Har Metrology: Results and Discussionmentioning

confidence: 99%

“…Dimensional metrology of high aspect ratio (HAR) features [1–11] will become more challenging as technology progresses, particularly in memory applications where designs are evolving from planar to vertical architectures with multi-level gates assembled in 3-D structures [3, 11–20]. The basic building blocks of these features are deep trenches and holes in oxide, silicon, or multiple alternating layers of oxide and silicon.…”

Section: Introductionmentioning

confidence: 99%

“…The basic building blocks of these features are deep trenches and holes in oxide, silicon, or multiple alternating layers of oxide and silicon. Furthermore, memory device scaling is headed towards aspect ratios ranging from 30:1 to 60:1, implying depths from 0.5 µm to 2 µm at the 32 nm and 11 nm International Technology Roadmap for Semiconductors (ITRS) node [3, 21] lateral dimensions. For example, HAR contact holes may be 1 µm in depth and 30 nm in diameter, for an aspect ratio of approximately 30:1 at the 32 nm node.…”

Section: Introductionmentioning

confidence: 99%

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Feasibility study on 3-D shape analysis of high-aspect-ratio features using through-focus scanning optical microscopy

Attota¹,

Weck

Kramar³

et al. 2016

Opt. Express

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In-line metrologies currently used in the semiconductor industry are being challenged by the aggressive pace of device scaling and the adoption of novel device architectures. Metrology and process control of three-dimensional (3-D) high-aspect-ratio (HAR) features are becoming increasingly important and also challenging. In this paper we present a feasibility study of through-focus scanning optical microscopy (TSOM) for 3-D shape analysis of HAR features. TSOM makes use of 3-D optical data collected using a conventional optical microscope for 3-D shape analysis. Simulation results of trenches and holes down to the 11 nm node are presented. The ability of TSOM to analyze an array of HAR features or a single isolated HAR feature is also presented. This allows for the use of targets with area over 100 times smaller than that of conventional gratings, saving valuable real estate on the wafers. Indications are that the sensitivity of TSOM may match or exceed the International Technology Roadmap for Semiconductors (ITRS) measurement requirements for the next several years. Both simulations and preliminary experimental results are presented. The simplicity, lowcost, high throughput, and nanometer scale 3-D shape sensitivity of TSOM make it an attractive inspection and process monitoring solution for nanomanufacturing.

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“…1 The standard method for photomask structure characterization is scanning electron microscopy (SEM). 2 This method is very powerful; however, the high cost of ownership and the low throughput are challenging factors. Furthermore, the accuracy of this method is limited by interactions between the electron beam and the photomask structures, which especially affects structures on insulating glass substrates.…”

Section: Introductionmentioning

confidence: 99%

Photomask CD and LER characterization using Mueller matrix spectroscopic ellipsometry

Heinrich

Dirnstorfer

Bischoff³

et al. 2014

SPIE Proceedings

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Critical dimension and line edge roughness on photomask arrays are determined with Mueller matrix spectroscopic ellipsometry. Arrays with large sinusoidal perturbations are measured for different azimuth angels and compared with simulations based on rigorous coupled wave analysis. Experiment and simulation show that line edge roughness leads to characteristic changes in the different Mueller matrix elements. The influence of line edge roughness is interpreted as an increase of isotropic character of the sample. The changes in the Mueller matrix elements are very similar when the arrays are statistically perturbed with rms roughness values in the nanometer range suggesting that the results on the sinusoidal test structures are also relevant for "real" mask errors. Critical dimension errors and line edge roughness have similar impact on the SE MM measurement. To distinguish between both deviations, a strategy based on the calculation of sensitivities and correlation coefficients for all Mueller matrix elements is shown. The Mueller matrix elements M 13 /M 31 and M 34 /M 43 are the most suitable elements due to their high sensitivities to critical dimension errors and line edge roughness and, at the same time, to a low correlation coefficient between both influences. From the simulated sensitivities, it is estimated that the measurement accuracy has to be in the order of 0.01 and 0.001 for the detection of 1 nm critical dimension error and 1 nm line edge roughness, respectively.

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Gaps analysis for CD metrology beyond the 22nm node

Cited by 57 publications

References 49 publications

Noise analysis for through-focus scanning optical microscopy

Noise analysis for through-focus scanning optical microscopy

Feasibility study on 3-D shape analysis of high-aspect-ratio features using through-focus scanning optical microscopy

Photomask CD and LER characterization using Mueller matrix spectroscopic ellipsometry

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