Stages of spin coating

Dielectric analysis of bulk polymer properties has been well documented. Similarly, DEA has often been employed in monitoring polymer reactions.Another, quite common application uses DEA to measure the breadth of a polymer relaxation. This analysis is directly related to the coupling parameter, which quantifies cooperativity. DEA has been used for characterizing thin polymer films. However, the polymer systems that have been studied involve free-standing films that have been sputter coated on both sides. Adding conductive substrates, such as aluminum foil, has also been accomplished, as well as relying on sputter coated, conducting surfaces. 

Thermal mechanical analysis can be used to assess the glass transition of a thin film system. The sample is placed in a temperature-controlled chamber for analysis. Two different probes can be used with thermal mechanical analysis (TMA) a flat probe or a penetration probe. The flat probe measures the thermal expansion of the polymer as the temperature is increased. Very little load is applied, so an accurate measure of change in dimension can be reported. Conversely, the penetration probe can have up to 1.0 N of force placed on the sample. The probe pushes into the sample as it softens to give a crude modulus (or compliance) value or a temperature associated with a 

For bulk polymers, both the coefficient of thermal expansion and the modulus have been measured as mentioned above.A more sensitive procedure has been developed for thin film analysis called local thermal analysis (LTA). In this technique the probe itself is heated and is therefore able to measure the expansion and transitions of thin films more accurately. 

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The four basic stages of spin coating (a) deposition, (b) acceleration, (c) flow domination, and (d) evaporation, co is spin speed. 

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