Mr. Vitali Khvatkov Profile

Vitali Khvatkov

Founder at Smart Imaging Technologies

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Publications (3)

Proceedings Article | 29 March 2011 Paper

Challenges of SEM-based critical dimension metrology of interconnect

Vladimir Ukraintsev, Scott Jessen, Brian Mikeska, Chris Sallee, Vitali Khvatkov

Proceedings Volume 7971, 797109 (2011) https://doi.org/10.1117/12.882183

KEYWORDS: Critical dimension metrology, Metrology, Scanning electron microscopy, Atomic force microscopy, Photoresist materials, Process control, Cadmium, Semiconducting wafers, Calibration, Optical proximity correction

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Semiconductor technology is advancing below 50 nm critical dimensions bringing unprecedented challenges to process engineering, control and metrology. Traditionally, interconnect metrology is put behind high-priority gate metrology; however, considering metrology, process and yield control challenges this decision is not always justified. Optical scatterometry is working its way to interconnect manufacturing process control, but scanning electron microscopy (SEM) remains the number one critical dimension (CD) metrology for interconnect process engineering and optical proximity correction (OPC) modeling. Recently, several publications have described secondary electron (SE) trapping within narrow high-aspect ratio interconnect structures. In these papers, pre-dosing of the sample helped to extract SE from the bottom of the hole and measure its diameter. Based on current understanding of the phenomenon, one should expect that high-aspect ratio interconnect structures (holes and trenches) with critical dimensions below 100 nm may show signs of SE trapping of various degree. As a result, there may be an uncontrolled effect on SE waveform and, therefore, bias of CDSEM measurement. CD atomic force microscopy (AFM) was employed in this work as a reference metrology for evaluation of uncertainty of trench and hole measurements by CDSEM. As the data indicates, CDSEM bias shows a strong dependence on pitch of periodic interconnect structure starting from drawn CD of 50 nm. CDSEM bias variation for the evaluated set of samples is about 19 nm. A typical OPC sample consists of both photoresist and etched interlayer materials. As the AFM data for photoresist material indicates, the hole diameter changes quite significantly with depth and the hole profile varies from one OPC structure to another. Abe et al. [1] have used a clever way to correlate physical bottom diameter of holes with CDSEM measurements and demonstrated that for their process and dimensions the SEM "top" diameter and physical bottom diameter correlate well. Unfortunately, this conclusion can't be generalized and measurement uncertainty of CDSEM must be evaluated on an individual technology/process basis. A more general approach to improve CDSEM accuracy is necessary which is based upon SI-traceable CDSEM bias measurements, modeling and correction.

Proceedings Article | 2 April 2010 Paper

From pin-point design based critical dimension metrology toward comprehensive evaluation of IC patterning integrity

Chris Sallee, Wayne Clark, Bo Jou Lu, Vladimir Ukraintsev, Vitali Khvatkov

Proceedings Volume 7638, 76382N (2010) https://doi.org/10.1117/12.848619

KEYWORDS: Image processing, Semiconducting wafers, Scanning electron microscopy, Imaging arrays, Feature extraction, Manufacturing, Optical lithography, Critical dimension metrology, Design for manufacturability, Printing

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Proceedings Article | 16 April 2008 Paper

Automated metrology for SEM calibration and CD line measurements using image analysis and SEM modeling methods

Vitali Khvatkov, Vasily Alievski, Radi Kadushnikov, Sergey Babin

Proceedings Volume 6922, 69222N (2008) https://doi.org/10.1117/12.774517

KEYWORDS: Scanning electron microscopy, Image processing, Critical dimension metrology, Metrology, Data modeling, Image analysis, Statistical analysis, Calibration, Signal detection, Image segmentation

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