Measuring the critical thickness of thin metalorganic precursor films

Successful application of sol-gel, metalorganic decomposition, or hydrother mal routes to ceramic thin films depends on the mechanical integrity of the precursor film. Above a critical thickness, a precursor film will crack or decohere from the substrate during drying. The cracking and thickness of t hin metalorganic precursor films were simultaneously observed during drying using a standard optical microscope. Isochromatic color fringes produced b y interference of reflected white light were used to monitor film thickness . The critical film thickness was determined by the color fringe correspond ing to the thickness at which propagating cracks terminated. As a demonstra tion of the technique, the critical thickness of titanium di(isopropoxide) bis(ethyl acetoacetate) films was measured, showing increased critical thic kness with the addition of small amounts of an elastomeric polymer.