Thickness-dependent thermal properties of amorphous insulating thin films measured by photoreflectance microscopy

Abstract

In this work, we report on the measurement of the thermal conductivity of thin insulating films of SiO 2 obtained by thermal oxidation, and Al 2 O 3 grown by atomic layer deposition (ALD), both on Si wafers. We used photoreflectance microscopy to determine the thermal properties of the films as a function of thickness in the 2 nm to 1000 nm range. The effective thermal conductivity of the Al 2 O 3 layer is shown to decrease with thickness down to 70% for the thinnest layers. The data were analyzed upon considering that the change in the effective thermal conductivity corresponds to an intrinsic thermal conductivity associated to an additional interfacial thermal resistance. The intrinsic conductivity and interfacial thermal resistance of SiO 2 were found to be equal to 0.95 ACCEPTED MANUSCRIPTA C C E P T E D M A N U S C R I P T W/m.K and 5.1x10 -9 m 2 K/W respectively; those of Al 2 O 3 were found to be 1.56 W/m.K and 4.3x10 -9 m 2 K/W.

Quantitative Mapping of Nanothermal Transport via Scanning Thermal Microscopy

“…There are four unknowns: the interface resistance R int , the contact radius a, the thermal conductivity of the layer k and the interface thermal resistance between the layer and the substrate r int . We obtained a realistic contact radius of a = 65.5 nm as well as for the ther-mal conductivity of the silicon oxide layers k = 1.0 Wm −1 K −1 being in a good agreement with optical technique measurements of similar sample [143]. The value of interface thermal resistance obtained (r int = 4.91 × 10 −8 m 2 KW −1 ) is around one order of magnitude higher than that found by Chien et al [144] but similar to that found by Zhu et al [145].…”

“…Then, we can use the 300 nm oxide sample as a calibration sample for the effective contact radius. By assuming literature values for the thermal conductivity (k SiO 2 ≈ 1W/mK [143,167]) and the interface thermal resistance between silicon oxide and silicon (r int Si−SiO 2 ≈ 1 × 10 −9 m 2 K/W [143,168]), we are left only with the effective contact radius. With these parameters, we obtained a = 56.1nm .…”

Room temperature direct bonding of diamond and InGaP in atmospheric air

“…Because the amorphous layer has lower thermal conductivity than the bulk materials, the increase of the amorphous layer thickness also has impact on the thermal boundary conductance. As reported, the thermal conductivity of the amorphous layer decreases by 70% when the thickness increases from 2 nm to 1000 nm [28]. Obviously, the decrease in the thermal conductivity of the amorphous layer formed at the diamond/InGaP interface due to the amorphous layer thickness increasing in several nanometers can be ignored.…”

Scanning thermal microscopy on samples of varying effective thermal conductivities and identical flat surfaces

“…Thermo-reflectance microscopy was used elsewhere [30] to measure the thermal conductivity kSiO2 of the sample, providing an intrinsic conductivity value for the SiO2 as well as the thermal resistance at the boundary rtbr between the SiO2 film and the Si substrate. Values determined are kSiO2 = 1.1 W.m -1 .K -1 and rtbr = 4.4 10 -8 m 2 .K.W -1 .…”

“…(1) at the sample surface and at the thin film/substrate boundary (z = t) for two heat source radii b (100 and 300 nm) and two film thicknesses t (237 and 65 nm). Thermoreflectance data was used for the the silicon dioxide film thermal conductivity and the thermal resistance at the boundary with silicon [30]. Fig.…”