Nanoscale Defect Analysis

As device sizes shrink, it becomes increasingly important to identify nanoscale defects as they directly interfere with device quality and production yields.  Here PiFM-IR demonstrates the ability to identify both organic and inorganic defects on particles that are only nanometers in size.

Image of nano IR (FTIR) spectra taken on polypropylene nano particle
An unknown defect is identified as a polypropylene particle. A series of spectra taken with 50 nm steps show the ability for PiFM-IR to highlight the substrate (Si with native oxide) and particle with spectra that correlate with the expected FTIR result.

While various analytical methods are used to try and identify unknown defects they are met with little success. Scanning electron microscopy can determine the shape of defects and if it is inorganic in nature use EDX to determine the elemental components. For organic materials, one can use mass spectrometer techniques to determine the composition, but the volume of material needed will limit success with this approach. In contrast, using PiFM-IR techniques it is possible to identify nanometer-sized particles independent of their composition be it either organic or inorganic. Moreover, PiFM-IR techniques are non-invasive and do not damage the sample or require special sample preparation.

Image of nano IR (FTIR) spectra taken on silica nano particle
PIFM-IR spectrum on silica nanoparticle. Spectral resonse shows difference in crystallinity between the silicon with native oxide and the SiOx particle.

PiFM-IR is able to provide excellent differentiation of minor chemical differences. As shown on this silicate particle in the image above, the PiFM-IR spectrum highlights the difference in crystallinity between the native oxide layer on the silicon substrate vs the silica particle. Most likely this particle is a remnant of a polishing compound.

Image of nano IR (FTIR) spectra taken on PTFE nano particle
100nm x 150nm in size and thinner than 5nm. PiFM-IR displays sharp IR absorption peaks at 1217 and 1158cm-1 that clearly identify the source of the defect. Note the clear difference in the IR PiFM spectra on (blue) and off (purple) the defect.

The featured image shows PiFM-IR spectra on and off this unknown particle, identified as PTFE (Teflon). The data shown here is power normalized, further processing could be conducted to subtract the sample contribution to the substrate to the sample spectrum.

Note: there is a longer version of this article with more details available here.

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