Film Thickness and error for 10 PMMA solution

Dielectric analysis (DBA) using both temperature and frequency sweeps can provide a direct measure of cooperativity. Because silicon is a semi-conductor, there were some concerns about consistent permittivity. The current would have to be high enough to allow the silicon wafer to conduct. The first test, then, was on a clean silicon wafer. 

With a direct measurement of cooperativity of the thin films via dielectric spectroscopy not attainable, attention was turned to probing the system indirectly. As discussed previously, changes in the glass transition temperature can indicate changing cooperativity. Thermal mechanical analysis (TMA) was used to survey the Tg of the system. Due to the favorable interactions of the PMMA side chains and the native oxide layer of silicon, the thinner films were expected to increase in cooperativity and therefore show an increase in Tg. The tests were started with the thickest films, 900 nm. 

As the system was heated, it expanded giving a constant increase in probe position. At the onset of the glass transition, the penetration probe should depress into the softening polymer. This depression appears to the instrument as if it observed a 

The instrument manual only presents a range for a displacement measurement of 25 mm. However, the dynamic deformation, which uses the same drive shaft, can gauge 

500 nm or more, which is too large for the thin films of this research. 

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Table 4.3-1 Film Thickness and error for 2% PMMA solution...

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