Absorption spectrum, silicon wafer with

Absorption spectrum, silicon wafer with a rough back surface, 222f... 

Infrared spectra were recorded on the resist film spun onto a silicon wafer using a JASCO IR-810 spectrometer equipped with a JASCO BC-3 beam condenser or a JASCO A-3 spectrometer. In the measurements on the latter spectrometer an uncoated silicon wafer was placed in the reference beam in order to balance the silicon absorption band. The subtraction between the spectra was carried out on a built-in micro-processor attached to the IR-810 spectrometer, and the resulting difference spectrum was used to detect structural changes in the polymer molecule upon exposure. The subtraction technique was also used to balance the silicon absorption band. 

As an example, both monofunctional and multifunctional polymeric mercapto-esters were deposited onto optically smooth silicon wafers coated with vapor-deposited copper. The copper had been oxidized to Cu20, as verified by XPS. Infrared reflectance (RAIRS) at 81° (4 cm-1 resolution, 2000 scans) using an MCT detector yielded information on both the nature and the durability of the mercaptoester bond to the metal oxide film. A 16 cm l shift (1740— 1724 cm-1) was observed in the carbonyl absorption of stearyl thioglycolate (STG) deposited onto the Cu20 mirror. The absorption spectrum of the carbonyl region is illustrated in Fig. 11, both for the pure STG and the reacted monolayer. 

The infrared (IR) spectrum reveals vibrations of atoms, ions, and molecular groups. The beauty of the spectrum is the close and accessible relationship between the IR bands and the molecular structure. Certain groups of atoms have characteristic vibrational frequencies that persist in different materials. Therefore, IR spectroscopy is an indispensable tool, widely employed to study sol-gel inorganic and organosilicon materials. FTIR spectroscopy is a common, sensitive, and nondestructive tool to record the IR absorption spectra of sol-gel films on transparent substrates such as silicon wafers, normally in the mid-IR range of 4000-400 cm , with a typical resolution of 4cm . Normal incidence IR absorption spectroscopy is often employed for the characterization of sol-gel materials. Gallardo et al. [18], however, used oblique incidence IR absorption for sol-gel films, which revealed some new structural features. 

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