Scatterometry-based metrology with feature region signatures matching

Ku, Yi-Sha; Wang, Shih-Chun; Shyu, Deh-Ming; Smith, Nigel

doi:10.1364/oe.14.008482

Cited by 25 publications

(13 citation statements)

References 7 publications

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“…However, AFM measurements over areas larger than the standard (5 x 5 µm) require special installations and measurement times increase significantly, [10]. A second common measurement technology in the semiconductor industry is so-called scatterometry which retrieves surface profile information based on reflected intensities, [11][12][13]. The technique relies on the reflection on periodic surface structures where a well-known model of the materials and the structures involved enable nmprecise measurements, [14,15].…”

Section: Introductionmentioning

confidence: 99%

Measurement of surface topographies in the nm-range for power chip technologies by a modified low-coherence interferometer

et al. 2016

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This work introduces a modified low-coherence interferometry approach for nanometer surface-prolometry. The key component of the interferometer is an element with known dispersion which defines the measurement range as well as the resolution. This dispersive element delivers a controlled phase variation which can be detected in the spectral domain and used to reconstruct height differences on a sample. In the chosen setup, both axial resolution and measurement range are tunable by the choice of the dispersive element. The basic working principle was demonstrated by a laboratory setup equipped with a supercontinuum light source (Δλ= 400-1700 nm). Initial experiments were carried out to characterize steps of 101 nm on a silicon height standard. The results showed that the system delivers an accuracy of about 11.8 nm. These measurements also served as a calibration for the second set of measurements. The second experiment consisted of the measurement of the bevel of a silicon wafer. The modified low-coherence interferometer could be utilized to reproduce the slope on the edge within the previously estimated accuracy. The main advantage of the proposed measurement approach is the possibility to collect data without the need for mechanically moving parts

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Section: Introductionmentioning

confidence: 99%

Measurement of surface topographies in the nm-range for power chip technologies by a modified low-coherence interferometer

et al. 2016

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“…Some efforts have been made to deal with this issue. Ku et al presented a feature region algorithm based on sensitivity analysis to reduce the scale of the signature library [24]. Littau et al investigated several techniques to determine an optimal signature scan path that can also result in a smaller signature library [25].…”

Section: Introductionmentioning

confidence: 99%

Improved measurement accuracy in optical scatterometry using correction-based library search

et al. 2013

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Library search is one of the most commonly used methods for solving the inverse problem in optical scatterometry. The final measurement accuracy of the conventional library search method highly depends on the grid interval selected for each parameter in the signature library, and the time cost of the parameter extraction increases dramatically when the grid interval is decreasing. In this paper, we propose a correction-based library search method to improve the measurement accuracy for a pregenerated signature library. We derive a formulation to estimate the error between the expected solution of the inverse problem and the actually searched solution obtained by the conventional library search method. Then we use the estimate of the error as a correction term to correct the actually searched solution to improve the measurement accuracy. Experiments performed on a photoresist grating have demonstrated that the proposed correction-based library search method can achieve much more accurate measurement with negligible computational penalty to the conventional library search method in the parameter extraction. It has also been observed that the correction-based library search method has higher measurement accuracy and less time cost than the interpolation-based library search method. The proposed correction-based library search method is expected to provide a more practical means to solve the inverse problem in state-of-the-art optical scatterometry.

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“…The principal task of scatterometry is detection and control of the deviation of a grating profile shape from the required one in grating manufacturing. Conventionally, it is performed by comparing the measured diffraction patterns (scattered field or other characteristics) with the theoretically calculated ones for a grating with desired profile, and subsequently determining whether the deviation is acceptable or not [1][2][3][4][5]. The technical facilities of modern lithography require theoretical models for a great variety of gratings profiles and materials.…”

Section: Introductionmentioning

confidence: 99%

“…The profound studies in practical scatterometry [1][2][3][4][5]22,23] assert that the simulation of measurement processes is very important not only for creation of the lookup tables facilitating the visualization process. The mathematical modeling oriented to extensive study of certain structures can result in the theoretically proven choice of the most efficient schemes for measuring.…”

Section: Introductionmentioning

confidence: 99%

Time-and-frequency domains approach to data processing in multiwavelength optical scatterometry of dielectric gratings

et al. 2013

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This paper focuses on scatterometry problems arising in lithography production of periodic gratings. Namely, the paper introduces a theoretical and numerical-modeling-oriented approach to scatterometry problems and discusses its capabilities. The approach allows for reliable detection of deviations in gratings' critical dimensions (CDs) during the manufacturing process. The core of the approach is the one-to-one correspondence between the electromagnetic (EM) characteristics and the geometric/material properties of gratings. The approach is based on highly accurate solutions of initial boundary-value problems describing EM waves' interaction on periodic gratings. The advantage of the approach is the ability to perform simultaneously and interactively both in frequency and time domains under conditions of possible resonant scattering of EM waves by infinite or finite gratings. This allows a detection of CDs for a wide range of gratings, and, thus is beneficial for the applied scatterometry.

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Scatterometry-based metrology with feature region signatures matching

Cited by 25 publications

References 7 publications

Measurement of surface topographies in the nm-range for power chip technologies by a modified low-coherence interferometer

Measurement of surface topographies in the nm-range for power chip technologies by a modified low-coherence interferometer

Improved measurement accuracy in optical scatterometry using correction-based library search

Time-and-frequency domains approach to data processing in multiwavelength optical scatterometry of dielectric gratings

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