Measuring Thin Film Thickness in Sub-Micron Samples with Microspectrometry

CRAIC Technologies is the worlds leading developer of UV-visible-NIR range scientific instruments for microanalysis. These include the QDI series UV-visible-NIR microspectrophotometer instruments designed to help you non-destructively measure the optical properties of microscopic samples. CRAIC's UVM series microscopes cover the UV, visible and NIR range and help you analyze with sub-micron resolutions far beyond the visible range. CRAIC Technologies also has the CTR series Raman microspectrometer for non-destructive analysis of microscopic samples. And don't forget that CRAIC proudly backs our microspectrometer and microscope products with unmatched service and support.

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Thin-Films in Integrated Circuits

Modern integrated circuits are made by depositing layers of different materials upon substrates and then etching circuits within those films. The thickness of the films must be precisely controlled in order to reproducibly manufacturer the integrated circuits that so much of our lives depend on. Commonly, the films are only tens of nanometers thick and have circuit dimensions in the sub-micron range.

Microspectrophotometers for Thin-Film Thickness Measurement

As such, microspectrophotometers, such as those manufactured by CRAIC Technologies, are one of the most effective tools to quickly, easily and reliably measure film thickness. Such film thickness measurement tools are designed to seamlessly integrate the microspectrophotometer with sophisticated software and automation in order to measure thin film thickness of sampling areas that can be smaller than a micron across. Such instruments are designed to measure film thickness of many types of films deposited upon many types of substrates.

Thin-Film Thickness Measurements on Transparent and Obaque Substrates

Thin film thickness measurements can be made on both transparent and opaque substrates which enables such tools to be used to monitor film thicknesses on such devices as flat panel displays in addition to semiconductor chips and MEMS devices.

Figure 1 is an example of an integrated circuit as seen through a CRAIC Technologies microspectrophotometer. The black square is the entrance aperture of the spectrophotometer itself. Light passing through that aperture is measured in terms of intensity versus wavelength. As one commonly sees with such thin films as oil on water, the result is an interference pattern whose peak locations are determined by a number of factors…including the thickness of the film. Figure 2 is one such example.

Figure 1. Integrated circuit as seen through a CRAIC Technologies microspectrophotometer

These three reflectance spectra are of three different thicknesses of silicon dioxide film deposited on a silicon substrate. Using these spectra, the QDI FilmPro™ software then models the thicknesses of each of the layers using a number of sophisticated algorithms. The results show that the red spectrum has a thickness of 10.1 nanometers, the blue a thickness of 30.0 nanometers and the green a measured thickness of 50.0 nanometers. This same technique can be used to measure film thickness by either transmission or reflectance of many types of materials and substrates. And due to the flexibility of the CRAIC Technologies thin film thickness measurement solutions, sampling areas can range from over 100 microns across to sub-micron.

This information has been sourced, reviewed and adapted from materials provided by CRAIC Technologies.

For more information on this source, please visit CRAIC Technologies.