Fourier Transform Infra-Red Spectrometry

Fourier Transform Infra-Red Spectrometry is used to characterize the chemical bonding present in solids, liquids and gases. A beam of infrared radiation is passed through a sample (or reflected off of a sample). Specific frequencies are absorbed by the sample's interatomic bonds through resonance. The absorbed frequencies are measured by an interferometer and related to the chemical bonding present in the sample. For many organic compounds, the infrared spectrum is a virtual fingerprint which may be used for positive identification. Extensive databases of FTIR spectra may be searched automatically to identify unknowns. The magnitude of infrared absorption may be used for quantitation. FTIR is frequently used to identify unknown compounds and contaminants found in process tools. Microscopic particles and residues measuring >50um can be examined with NicPlan microscope accessory. Other FTIR applications include measurement of the interstitial oxygen content of silicon wafers, measurement of epitaxial film thicknesses, measurement of hydrogen and water in silicon oxide, silicon nitride and BPSG films and measurement of polymer film degree of cure.