PULSED ELECTROTHERMAL TECHNIQUE FOR MEASURING THE THERMAL-DIFFUSIVITYOF DIELECTRIC FILMS ON CONDUCTING SUBSTRATES

A simple technique for measuring the thermal diffusivity of dielectric films on thermally sinking substrates is proposed and demonstrated. I t is an outgrowth of the thermal purse technique for measuring charge and polarization profiles. The thermal diffusivity is derived from the transient electrical response induced by a thermal pulse applied to a de voltage-biased sample. Because the response is proportional to the bias voltage, the signal-to-noise ratio is adjustable independently o f the thermal pulse energy and may be made as large as required for de termining the diffusivity with high precision. Measuring times of arou nd 1 ms or shorter are sufficient for polymers with thicknesses up to 10 mu m. Experimental results for two different polyimide films spin c oated on crystalline silicon substrates are presented and discussed. ( C) 1996 American Institute of Physics.