Computational Adaptive Optics for HAR Hybrid Trench Array Topography Measurement by Utilizing Coherence Scanning Interferometry

High aspect ratio (HAR) sample-induced aberrations seriously affect the topography measurement for the bottom of the microstructure by coherence scanning interferometry (CSI). Previous research proposed an aberration compensating method using deformable mirrors at the conjugate position of the pupil...

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Vydáno v:Sensors (Basel, Switzerland) Ročník 25; číslo 13; s. 4085
Hlavní autoři: Qiao, Wenyou, Gao, Zhishan, Yuan, Qun, Chen, Lu, Guo, Zhenyan, Huo, Xiao, Wang, Qian
Médium: Journal Article
Jazyk:angličtina
Vydáno: Switzerland MDPI AG 30.06.2025
MDPI
Témata:
aberration correction
Algorithms
Astigmatism
coherence scanning interferometry
Electric fields
high aspect ratio
Interferometry
Light
Mathematical optimization
Measurement
Optics
Optimization
Polynomials
sample-induced aberrations
Signal to noise ratio
Simulation
Topography
virtual phase filter
virtual phase filter
sample-induced aberrations
high aspect ratio
coherence scanning interferometry
aberration correction
topography
ISSN:1424-8220, 1424-8220
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Shrnutí:High aspect ratio (HAR) sample-induced aberrations seriously affect the topography measurement for the bottom of the microstructure by coherence scanning interferometry (CSI). Previous research proposed an aberration compensating method using deformable mirrors at the conjugate position of the pupil. However, it failed to compensate for the shift-variant aberrations introduced by the HAR hybrid trench array composed of multiple trenches with different parameters. Here, we propose a computational aberration correction method for measuring the topography of the HAR structure by the particle swarm optimization (PSO) algorithm without constructing a database and prior knowledge, and a phase filter in the spatial frequency domain is constructed to restore interference signals distorted by shift-variant aberrations. Since the aberrations of each sampling point are basically unchanged in the field of view corresponding to a single trench, each trench under test can be considered as a separate isoplanatic region. Therefore, a multi-channel aberration correction scheme utilizing the virtual phase filter based on isoplanatic region segmentation is established for hybrid trench array samples. The PSO algorithm is adopted to derive the optimal Zernike polynomial coefficients representing the filter, in which the interference fringe contrast is taken as the optimization criterion. Additionally, aberrations introduce phase distortion within the 3D transfer function (3D-TF), and the 3D-TF bandwidth remains unchanged. Accordingly, we set the non-zero part of the 3D-TF as a window function to preprocess the interferogram by filtering out the signals outside the window. Finally, experiments are performed in a single trench sample and two hybrid trench array samples with depths ranging from 100 to 300 μm and widths from 10 to 30 μm to verify the effectiveness and accuracy of the proposed method.
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ISSN:1424-8220
1424-8220
DOI:10.3390/s25134085