Nanoscale defect detection by heterodyne interferometry

Lin, Hong‐Yan; Li, Yuhe; Wang, Dongsheng; Xiaolei, Tong; Liu, Mei

doi:10.1364/ao.48.001502

Cited by 3 publications

(2 citation statements)

References 23 publications

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“…对超精加工表面进行检测是盘片或晶片制造过程中的重要组成部分。电子产品高集成化和高性能化发展，要求对抛光盘片或晶片的超精表面缺陷检测实现纳米级分辨率进而提高成品率。相对于表面检测技术如光学干涉法等 [1][2][3] ，外差干涉与探针扫描集成化检测技术则具有纳米级的纵向、横向分辨率和高的测量精度 [4] 。然而，激光外差干涉光路中两个频率的偏振光不能彻底分开而形成的非线性混频误差对系统检测性能有至关重要影响 [5][6][7] 。多年来许多学者对激光外差干涉非线性误差进行了理论与实验研究 [7][8][9][10][11][12][13][14][15][16][17][18]…”

Section: 引言unclassified

Error Analysis of Optical Frequency Mixing on Detecting Device for Superfinish Surface Scratch

Haoshan¹,

Juke²,

Yuhe³

et al. 2015

激光与光电子学进展

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A novel method with high resolution has been proposed which is based on heterodyne interferometry and scanning probe to get the measurement values of superfinish surface scratch. But the optical nonlinear errors affect the measurement precision of the system. We adopt the Jones matrix to analyze the change of elliptic polarization caused by the composite error factors, which are polarization ellipticity and installation orientation error of laser source, phase retardation of quarter-wave plate and polarization leakage of polarization beam splitter. The measurement errors of frequency mixing about these elliptic polarization beams arriving at the photodiode detector are studied by vector theory. The results show that the measurement errors are periodic errors, and they are more affected by nonideal laser and polarization beam splitter. Also, the methods of reducing nonlinear error according to the numerical results in the system are suggested.

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Section: 引言unclassified

Error Analysis of Optical Frequency Mixing on Detecting Device for Superfinish Surface Scratch

Haoshan¹,

Juke²,

Yuhe³

et al. 2015

激光与光电子学进展

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“…The measurement principle can be referred to in our previous report. [10] The heterodyne signals of tip deflection are recorded and processed at a 200 kHz sampling frequency by the phase meter. Subsequently, the output signals are sent to the computer for relative processing, such as fast Fourier transforming, band-pass filtering, calculation for the harmonic amplitudes and corresponding frequency spectra.…”

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confidence: 99%

Second Harmonic Generation in Scanning Probe Microscopy for Edge Localization

Xiao-Gen¹,

Li²,

Lin³

et al. 2011

Chinese Phys. Lett.

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We present an approach of second harmonic generation for edge localization of nano-scale defects measurement, based on the impact of the oscillating tip on the sample that induces higher harmonics of the excitation frequency. The harmonic signals of tip motion are measured by the heterodyne interferometry. The edge amplitude ratio for the edge characterization can be calculated by a mechanics model and the threshold of edge localization is experimentally determined by second harmonic profiles. This approach has been successfully utilized to measure the pitch of a standard sample. The results show that the second harmonic is sensitive to locating the edge of nano-scale defects with high accuracy.

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Nanoscale surface topography imaging using phase-resolved spectral domain optical coherence tomography

Wang¹,

Guo²,

Luan³

et al. 2017

Acta Phys. Sin.

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Microscopic surface topography plays an important role in studying the functions and properties of materials. Microscopic surface topography measurement has been widely used in many areas, such as machine manufacturing, electronic industry and biotechnology. Optical interferometry is a popular technique for surface topography measurement with an axial resolution up to nanoscale. However, the application of this technique is hampered by phase wrapping, which results in a limited measurement range for this technique. Various digital algorithms for phase unwrapping have been proposed based on the phase continuity between two adjacent points. However, several significant challenges still exist in recovering correct phase with this technique. Optical coherence tomography (OCT) is a non-contact three-dimensional imaging modality with high spatial resolution, and it has been widely used for imaging the biological tissues. In this paper, we demonstrate a method for nanoscale imaging of surface topography by using common-path phase-resolved spectral domain OCT to reduce the influence of phase wrapping. The system includes a superluminescent diode with a central wavelength of 1310 nm and a spectral bandwidth of 62 nm, an optical fiber circulator, a home-made spectrometer, and a reference arm and a sample arm in common-path arrangement. The reference mirror and the sample under investigation are positioned on a same stage in order to further reduce the influence of ambient vibration. The phase difference between two adjacent points is calculated by performing Fourier transform on the measured interferometric spectrum. The phase difference distribution of the surface is obtained first. And then, the surface topography of the sample is constructed by integrating the phase difference distribution. In the traditional methods, phase wrapping occurs if the absolute value of the measured phase is greater than . However, in the present method, phase wrapping occurs if the absolute value of the phase difference between two adjacent points is greater than . The maximal detectable absolute value of the phase difference between two adjacent points increases from for the traditional methods to 2 for the present method. The experimental results indicate that the present system has a high stability and the maximum fluctuation is less than 0.3 nm without averaging. The accuracy of the system is tested with a piezo stage, and the mean absolute deviation of the measured results is 0.62 nm. The performance of the present system is also demonstrated by the surface topography imaging of an optical resolution test target and a roughness comparison specimen. The experimental result shows that the present system is a potential powerful tool for surface topography imaging with an axial resolution better than 1 nm.

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Nanoscale defect detection by heterodyne interferometry

Cited by 3 publications

References 23 publications

Error Analysis of Optical Frequency Mixing on Detecting Device for Superfinish Surface Scratch

Error Analysis of Optical Frequency Mixing on Detecting Device for Superfinish Surface Scratch

Second Harmonic Generation in Scanning Probe Microscopy for Edge Localization

Nanoscale surface topography imaging using phase-resolved spectral domain optical coherence tomography

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