Robust incident angle calibration of angle-resolved ellipsometry for thin film measurement

Abstract

Angle-resolved ellipsometry with back focal plane imaging has been found to be of increasing importance in recent industrial sensing by virtue of its rich information provided at various incident and azimuthal angles. To achieve high sensing accuracy, the incident angles of a back focal plane must be accurately calibrated. For this purpose, a simple and robust incident angle calibration method based on full-field Brewster angle fitting is proposed, without expensive tools or complex operations. With this method, a back focal plane image is first captured from boundary reflectance through a high-numerical-aperture objective. By extracting annular data from the image, radius-dependent ellipsometric parameters ( ψ , Δ ) are calculated. At the end, the radii of the back focal plane are mapped to the angle of incidence by using a fitted Brewster angle as the reference. The method is validated by simulation and experiments using a homemade angle-resolved ellipsometer and a commercial spectroscopic ellipsometer. The results show that the proposed method provides a 75% error reduction approximately from generally used methods.

Atomic layer deposition in advanced display technologies: from photoluminescence to encapsulation

“…More specifically, Arteaga and Kahr [106] observed several thin freestanding crystal slabs using a homemade Mueller matrix conoscope. Moreover, back focal plane (BFP)-related methods [107][108][109], such as angle-resolved ellipsometry and reflectometry, have been verified for their ability to carry out nanometer thin-film single-shot measurements. Such techniques have the potential to carry out rapid measurements on thin films that have been coated on anisotropic substrates.…”

“…Figure 7(b) illustrates the polarized angle-resolved reflectometry (PARS) setup [109], which includes the illumination source, the measurement probe, and the detection unit. In this system, the collimated white light becomes linearly polarized after passing through a linear polarizer set at 0 • , and is refocused on the BFP of the objective lens.…”

Transparent anisotropic films measurement with a polarized angle-resolved spectroscopy

“…Figure 1(a) illustrates a system layout of our homemade PARS. Before the experiment started, the calibration was carried out, as seen in our previous study [9]. Thus, full azimuth and incident angle-resolved spectra (FARS) were captured by CMOS with a filter (@632.8 nm), and wavelength and incident angle-resolved spectra (WARS) were captured by the imaging spectrometer.…”

Improving the accuracy and precision of OCD measurement by systematic error correction in self-interference pupil ellipsometry

“…Ellipsometry-based OCD measurement methods are being studied into various types such as faster measurement speed or massive expansion of the measurable data domain to meet the requirements of the semiconductor manufacturers. Among them, spectroscopic ellipsometry using spectral signals, variable angle spectral ellipsometry (VASE) 1,2 that can measure various angles of incidence and azimuth signals, imaging ellipsometry 3,4 that can increase spatial resolution and acquire signals for a region, and micro-ellipsometry 5,6 which can measure various angle of incidence and azimuth angle in oneshot, are being studied. Among various OCD measurement methods, micro-ellipsometry is a promising OCD technique as it enables massive angular measurements and small-spot illumination.…”

“…Among various OCD measurement methods, micro-ellipsometry is a promising OCD technique as it enables massive angular measurements and small-spot illumination. Various micro-ellipsometry techniques have been studied by global research centers 7,8 and global metrology and inspection companies including KLA, ASML, and Onto Innovation [9][10][11][12][13][14][15][16] . We also have recently proposed interferometric micro-ellipsometry, named self-interference pupil ellipsometry (SIPE) 17,18 .…”