Thermal Characterization of Nm-thin Nb2O5 by Applying Thermal Impedance Methods to Time Domain Thermoreflectance Measurements

The time domain thermal reflectance (TDTR) method enables thermal investigations of films in the nanometre range, which can be found in microelectronic devices. In this study, a 166 nm thick Diniobium pentoxide layer (Nb
₂
O
₅
), which is used in capacitors, optical devices as well as precursors, was investigated by using TDTR method. This layer was studied by its thermal transients in the (sub-)nanosecond time range at temperatures from 25°C to 500°C. In this paper, these thermal transients of the Nb
₂
O
₅
layer were analysed by three evaluation approaches: One analytical and two numerical approaches, the relative thermal resistance method and the structure function method. The analytical approach revealed that its thermal diffusivity and thermal conductivity increases with rising temperature from (0.43 to 0.74) mm/s and from (1.0 to 2.3) W/mK. The numerical approaches enables to get rid of certain up-front assumptions, which are necessary when applying analytical solution and enables deeper understanding of the Nb
₂
O
₅
thermal behaviour.