Wuhan Eoptics Technology Co.

Wuhan, China

Wuhan Eoptics Technology Co.

Wuhan, China
SEARCH FILTERS
Time filter
Source Type

Tao Z.,Huazhong University of Science and Technology | Liu J.-M.,Huazhong University of Science and Technology | Zhang C.-W.,Huazhong University of Science and Technology | Zhang C.-W.,Wuhan Eoptics Technology Co. | And 4 more authors.
Hongwai Yu Haomibo Xuebao/Journal of Infrared and Millimeter Waves | Year: 2016

A new compact polarized spectrometer is reported and implemented. An array consisting of two spectrometers is employed in the proposed polarized spectrometer to enable the measurement in the entire visible spectral range, which is necessary for the measurement of different sample types. Only one polarization optical element is used in the optics system with the partially parallel optical path design, which significantly simplifies the configuration and calibration of the system. The compact polarized spectrometer utilizes the incident plane rotating effect to modulate the polarization state in space domain, which consequently reduces the measurement time. The accuracy of the proposed compact polarized spectrometer is demonstrated by measuring test samples with different thicknesses. In consideration of the advantages, such as fast speed, compact and concise structure, eases integration, the proposed instrument shows great potential to be a powerful tool for on-line measurement in thin film manufacturing. © 2016, Science Press. All right reserved.


Chen X.,Huazhong University of Science and Technology | Gu H.,Huazhong University of Science and Technology | Jiang H.,Huazhong University of Science and Technology | Zhang C.,Huazhong University of Science and Technology | And 3 more authors.
Optics Express | Year: 2017

Overlay control is of vital importance to good device performances in semiconductor manufacturing. In this work, the differential Mueller matrix calculus is introduced to investigate the Mueller matrices of double-patterned gratings with overlay displacements, which helps to reveal six elementary optical properties hidden in the Mueller matrices. We find and demonstrate that, among these six elementary optical properties, the linear birefringence and dichroism, LB′ and LD′, along the ± 45° axes show a linear response to the overlay displacement and are zero when the overlay displacement is absent at any conical mounting. Although the elements from the two 2 x 2 off-diagonal blocks of the Mueller matrix have a similar property to LB′ and LD′, as reported in the literature, we demonstrate that it is only valid at a special conical mounting with the plane of incidence parallel to grating lines. The better property of LB′ and LD′ than the Mueller matrix elements of the off-diagonal blocks in the presence of overlay displacement verifies them to be a more robust indicator for the diffraction-based overlay metrology. © 2017 Optical Society of America.


Li W.,Huazhong University of Science and Technology | Jiang H.,Huazhong University of Science and Technology | Zhang C.,Huazhong University of Science and Technology | Zhang C.,Wuhan Eoptics Technology Co. | And 4 more authors.
Journal of Vacuum Science and Technology B: Nanotechnology and Microelectronics | Year: 2016

The authors apply Mueller matrix ellipsometry to characterize the curved surface layers, by utilizing the noticeable anisotropy observed from the measured data. The authors demonstrate that this anisotropy is introduced by the curved surface shape as well as the misalignment between the illumination spot and the surface vertex. An optical model is proposed to expound the anisotropy, and is applied to evaluate the curved thin thermal oxide layer on a silicon sphere crown. After incorporating the proposed optical model in the parameter extraction, the experimental results show that not only will the accuracy of the oxide layer thickness measurement at an arbitrary location on the surface be improved, the curvature radius as well as the position of detection can also be determined directly. © 2016 American Vacuum Society.


Gu H.,Huazhong University of Science and Technology | Jiang H.,Huazhong University of Science and Technology | Zhang C.,Huazhong University of Science and Technology | Zhang C.,Wuhan Eoptics Technology Co. | And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

The diagnosis and control of the polarization aberrations is one of the main concerns in a hyper numerical aperture (NA) lithography system. Waveplates are basic and indispensable optical components in the polarimetric diagnosis tools for the immersion lithography system. The retardance of a birefringent waveplate is highly sensitive to the incident angle of the light, which makes the conventional waveplate not suitable to be applied in the polarimetric diagnosis for the immersion lithography system with a hyper NA. In this paper, we propose a method for the optimal design of a wideview-angle waveplate by combining two positive waveplates made from magnesium fluoride (MgF2) and two negative waveplates made from sapphire using the simulated annealing algorithm. Theoretical derivations and numerical simulations are performed and the results demonstrate that the maximum variation in the retardance of the optimally designed wide-view-Angle waveplate is less than ± 0.35° for a wide-view-Angle range of ± 20°. © 2016 SPIE.


Li W.,Huazhong University of Science and Technology | Zhang C.,Huazhong University of Science and Technology | Zhang C.,Wuhan Eoptics Technology Co. | Jiang H.,Huazhong University of Science and Technology | And 3 more authors.
Journal of Optics (United Kingdom) | Year: 2016

Noticeable depolarization effects are observed in the measurement of the air using an in-house developed dual rotating-compensator Mueller matrix ellipsometer. We demonstrate that these depolarization effects are essentially artifacts and mainly induced when the compensator with wavelength-dependent optical properties is integrated with the finite bandwidth detector. We define a general formula to represent the actual Mueller matrix of the compensator by taking into account the depolarization artifacts. After incorporating this formula into the system model, a correction method is further proposed, and consequently, improved accuracy can be achieved in the Mueller matrix measurement. © 2016 IOP Publishing Ltd.


Honggang G.U.,Huazhong University of Science and Technology | Chen X.,Huazhong University of Science and Technology | Jiang H.A.O.,Huazhong University of Science and Technology | Zhang C.,Huazhong University of Science and Technology | And 4 more authors.
Applied Optics | Year: 2016

The biplate that consists of two single wave plates made from birefringent materials with their fast axes oriented perpendicular to each other is one of the most commonly used retarders in many optical systems. The internal alignment of the optical axes of the two single wave plates is a key procedure in the fabrication and application of a biplate to reduce the spurious artifacts of oscillations in polarization properties due to the misalignment error and to improve the accuracy and precision of the systems using such biplates. In this paper, we propose a method to accurately align the axes of an arbitrary biplate by minimizing the oscillations in the characteristic parameter spectra of the biplate detected by a spectroscopic Mueller matrix ellipsometer (MME). We derived analytical relations between the characteristic parameters and the misalignment error in the biplate, which helps us to analyze the sensitivity of the characteristic parameters to the misalignment error and to evaluate the alignment accuracy quantitatively. Experimental results performed on a house-developed MME demonstrate that the alignment accuracy of the proposed method is better than 0.01° in aligning the optical axes of a quartz biplate. © 2016 Optical Society of America.


Chen X.,Huazhong University of Science and Technology | Shi Y.,Huazhong University of Science and Technology | Jiang H.,Huazhong University of Science and Technology | Zhang C.,Huazhong University of Science and Technology | And 3 more authors.
Applied Surface Science | Year: 2016

Mueller matrix ellipsometry (MME) is applied to characterize lithographic patterns with natural line edge roughness (LER). A computationally efficient approach based on effective medium approximation is proposed to model the effects of LER in MME measurements. We present both the theoretical and experimental results on lithographic patterns with realistic LER which demonstrate that MME in combination with the proposed effective modeling method is capable of quantifying LER amplitudes. Quantitative comparisons between the MME and scanning electron microscopy measured results also reveal the strong potential of this technique for in-line nondestructive line roughness monitoring. © 2015 Elsevier B.V.


Gu H.,Huazhong University of Science and Technology | Chen X.,Huazhong University of Science and Technology | Jiang H.,Huazhong University of Science and Technology | Zhang C.,Huazhong University of Science and Technology | And 3 more authors.
Journal of Optics (United Kingdom) | Year: 2016

Accurate measurement of the Mueller matrix over a broad band is highly desirable for the characterization of nanostructures and nanomaterials. In this paper, we propose a general composite waveplate (GCW) that consists of multiple waveplates with flexibly oriented axes as a polarization modulating component in the Mueller matrix ellipsometer (MME). Although it is a common practice to make achromatic retarders by combining multiple waveplates, the novelty of the GCW is that both the retardances and azimuths of fast axes of the single-waveplates in the GCW are flexible parameters to be optimized, which is different from the conventional design where single-waveplates are usually arranged in symmetrical layout or with their fast axes parallel or perpendicular to each other. Consequently, the GCW can provide many more flexibilities to adapt to the optimization of the MME over a broad band. A quartz triplate, as a concrete example of the GCW, is designed and used in a house-made MME. The experimental results on the air demonstrate that the house-made MME using the optimally designed quartz triplates has an accuracy better than 0.2% and a precision better than 0.1% in the Mueller matrix measurement over a broad spectral range of 200∼1000 nm. The house-made MME exhibits high measurement repeatability better than 0.004 nm in testing a series of standard SiO2/Si samples with nominal oxide layer thicknesses ranging from 2 nm to 1000 nm. © 2016 IOP Publishing Ltd.


Gu H.,Huazhong University of Science and Technology | Zhang C.,Huazhong University of Science and Technology | Zhang C.,Wuhan Eoptics Technology Co. | Jiang H.,Huazhong University of Science and Technology | And 4 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

Dual-rotating compensator Mueller matrix ellipsometer (DRC-MME) has been designed and applied as a powerful tool for the characterization of thin films and nanostructures. The compensators are indispensable optical components and their performances affect the precision and accuracy of DRC-MME significantly. Biplates made of birefringent crystals are commonly used compensators in the DRC-MME, and their optical axes invariably have tilt errors due to imperfect fabrication and improper installation in practice. The axis tilt error between the rotation axis and the light beam will lead to a continuous vibration in the retardance of the rotating biplate, which further results in significant measurement errors in the Mueller matrix. In this paper, we propose a simple but valid formula for the retardance calculation under arbitrary tilt angle and azimuth angle to analyze the axis tilt errors in biplates. We further study the relations between the measurement errors in the Mueller matrix and the biplate axis tilt through simulations and experiments. We find that the axis tilt errors mainly affect the cross-talk from linear polarization to circular polarization and vice versa. In addition, the measurement errors in Mueller matrix increase acceleratively with the axis tilt errors in biplates, and the optimal retardance for reducing these errors is about 80°. This work can be expected to provide some guidences for the selection, installation and commissioning of the biplate compensator in DRC-MME design. © 2015 Copyright SPIE.


Li W.,Huazhong University of Science and Technology | Zhang C.,Huazhong University of Science and Technology | Zhang C.,Wuhan Eoptics Technology Co. | Jiang H.,Huazhong University of Science and Technology | And 4 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

Mueller matrix ellipsometry has been demonstrated as a powerful tool for nanostructure metrology in high-volume manufacturing. Many factors may induce depolarization effect in the Mueller matrix measurement, and consequently, may lead to accuracy loss in the nanostructure metrology. In this paper, we propose to apply a Mueller matrix decomposition method for the Mueller matrix measurement to separate the depolarization effect caused by the MME system. The method is based on the polar decomposition by decomposing the measured depolarizing Mueller matrix into a sequence of three matrices corresponding to a diattenuator followed by a retarder and a depolarizer. Since the depolarization effects will be only reflected in the depolarizer matrix, the other two matrices are used to extract the structure parameters of the measured sample. Experiments performed on a one-dimensional silicon grating structure with an in-house developed MME layout have demonstrated that the proposed method achieves a higher accuracy in the nanostructure metrology. © 2015 Copyright SPIE.

Loading Wuhan Eoptics Technology Co. collaborators
Loading Wuhan Eoptics Technology Co. collaborators