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Wavelength Scanning Interferometer

As part of the NanoMend project, IBS Precision Engineering has been working together with the Centre for Process Innovation (CPI) and the University of Huddersfield to design and manufacture a state-of-the-art Wavelength Scanning Interferometer system that enables the fast surface measurement of low contrast defects at pre-industrial scale.

The tool has been installed in the United Kingdom at CPI’s National Printable Electronics Centre in June 2014. There its in-line metrology capability is being demonstrated and optimised.

Current industry standard interferometry systems generally work by mechanically scanning the position of a lens relative to the substrate being measured. Such a technique is too slow to perform the large number of measurements required to enable defect detection analysis for large-scale thin film barriers. The solution to this is to use wavelength scanning, which is able to produce a fast, quantitative measurement of the film layer topographies in the form of a three dimensional image. The latter can provide richer information on the nature of the defect, so influence on the layer properties can be assessed.

By designing and developing an interferometer with a patented integrated environmental compensation technique, IBS Precision Engineering and the University of Huddersfield have developed an ultra-high-precision metrology tool suitably robust for application within a production environment.

Comparison of the measurement data between the WSI and a traceable CMM have confirmed a vertical accuracy of approximately 15nm; proving WSI as a high-accuracy metrology instrument for the rapid measurement of micro- and nanoscale surfaces.

Specification Value
Vertical range (lens-dependent) 96 µm
Vertical resolution < 2 nm
Vertical accuracy ~15 nm
Lateral range (lens-dependent) 2,8 x 2,8 mm2
Lateral sampling 1024 x 1024 pixels
Lateral resolution (lens-dependent) 5 µm
Measurement time < 1 second
Autofocus time < 1 second

 

Available downloads:

Wavelength Scanning Interferometer Technote

Article on the Wavelength Scanning Interferometer in Mikroniek magazine's April 2014 edition.