Pulsed electrothermal technique for measuring the thermal diffusivity of dielectric films on conducting substrates

Abstract

A simple technique for measuring the thermal diffusivity of dielectric films on thermally sinking substrates is proposed and demonstrated. It is an outgrowth of the thermal pulse 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 dc voltage-biased sample. Because the response is proportional to the bias voltage, the signal-to-noise ratio is adjustable independently of the thermal pulse energy and may be made as large as required for determining the diffusivity with high precision. Measuring times of around 1 ms or shorter are sufficient for polymers with thicknesses up to 10 μm. Experimental results for two different polyimide films spin coated on crystalline silicon substrates are presented and discussed.

Thermal diffusivity of aromatic polyimide thin films by temperature wave analysis

“…By contrast, this method has been successfully utilized to measure the thermal conductivity of thin semiconductor films on substrates. [52][53][54][55][56][57][58][59][60][61][62][63][64][65][66] From another standpoint noncontact novel and specialized photothermal methods [67][68][69][70][71][72][73][74] have been developed and applied to measure the thermal conductivity and diffusivity of aromatic polyimide thin films. The in-plane measurement by noncontact has been reported, however, the data vary widely between different methods and groups and a good uncertainty level has not yet been common.…”

Pyroelectric polymer electrets

“…Gerhard-Multhaupt and Xia [134] reported on the inversion of the thermal pulse techruque for the determination of temperature distributions in charged electret films. DeReggi and Bauer [135] adapted the thermal pulse technique for the measurement of the thermal diffusivity of thm polymer films on hghly conducting substrates. The techruque is based on electric-field induced pyroelectricity and is thus applicable to the investigation of any kind of material.…”

<title>Pulsed electrothermal technique for the characterization of dielectric films</title>

“…The whole setup is controlled by a microcomputer and allows for in-situ measurements during thermal cycles. Optionally, a dc-bias field can be applied, enabling measurements of not only poiar films, but also any other insulating dielectric [10]. The electrical response of the sample after thermal excitation arises from primary and secondary pyroelectricity.…”

“…In poled polar samples, the thermal diffusivity can be determined from the analysis of the pyroelectric response, while in any other insulating dielectrics, field-induced pyroelectric signals can be analyzed [10]. Fig.…”

“…However, it will be shown here that adaptations of the well-known thermal techniques for the depth-profiling of nonuniform spatial distributions of electric field and dipole polarization [1][2][3][4][5][6] (pulsed electrothermal techniques) provide an elegant means: S for the measurement ofthe pyroelectric, piezoelectric, elastic and thermal properties of dielectrics [7][8][9][10], . for the investigation of dipole relaxation processes in amorphous polymers and phase transitions in ferroelectric polymers [7], as well as for S the monitoring of nonuniform polarization distributions during thermally stimulated depolarization.…”