Coherent Fourier Scatterometry for the fast and sensitive detection of subwavelength structures and particles

We investigate and optimize new techniques to detect nanostructures and nano-particles in semiconductor, and plastic-based fabrication technologies. The technique should be fast, operate in-line and applicable to large areas. Since the structures are too small to be imaged, a technique called scatterometry is implemented.

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Objective

Important question appears with regard to the problem of contamination detection and improved performance of the systems used for quality inspection of ICs. What is the realistic detection limit of our light-field scattering-based technique for the detection of low-contrast nanoparticles on top of substrates used in the semiconductor industry?

We propose to improve the sensitivity and resolution of scatterometry by utilizing an optimized focused illumination in combination with improved detection schemes, all depending on the sample being inspected. With currently available modern optoelectronic spatial light modulators and deformable mirrors, the amplitude, phase and polarization of the optimal optical fields in the entrance pupil of the focusing objective can be position-dependently shaped to obtain a focused field that gives maximum sensitivity to the nominal structure parameters. In addition, we can refine the detector system to collect critical information at high speed and to minimize the effect of noise on the machine.  Finally, as it is necessary to test wider areas up to a few cm2 in a few minutes in several applications, we will develop a parallelized version of the optimized illumination and detection systems for this reason.

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Impact

We make a positive impact on every level of society.  Think of more economical healthcare systems, energy-efficient transportation systems, more affordable education to everyone.  We achieve this by positively influencing the process of IC’s manufacturing which, in its turn, via microchips size reduction makes possible better living.

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Publications

• Convolutional neural network applied for nanoparticle classification using coherent scatterometry data

  D. Kolenov, D. Davidse, J. Le Cam, and S. F. Pereira, Appl. Opt. 59, 84268433 (2020)

• Machine learning techniques applied for the detection of nanoparticles on surfaces using coherent Fourier scatterometry

  D. Kolenov and S. F. Pereira, Opt. Express 28, 1916319186 (2020)

• Effect of polarization in evanescent wave amplification for the enhancement of scattering of nanoparticles on surfaces

  D. Kolenov, H. P. Urbach, and S. F. Pereira, OSA Continuum 3, 742758 (2020)

• A highly sensitive laser focus positioning method with submicrometre accuracy using coherent Fourier scatterometry

  D. Kolenov, P. Meng, and S.F. Pereira, Measurement Science and Technology 31 (6) 064007 (2020)

• Heterodyne detection system for nanoparticle detection using coherent Fourier scatterometry

  D. Kolenov, R. C. Horsten, S. F. Pereira, Proc. SPIE 11056, Optical Measurement Systems for Industrial Inspection XI, 110561A (2019)