Thermal and electrical characterization and modeling of thin copper layers

This paper presents the experimental and theoretical study on the effects of electron scattering at grain and boundaries on the reduction of effective thermal conductivity. The present study measures the electrical resistivity and lateral thermal conductivity of thin copper layers of thicknesses 50 and 144 nm at temperatures between 40 and 400 K, using Joule heating and electrical-resistance thermometry in suspended micro fabricated structures. A fitting model including the size effect and grain boundary scattering is used to model the thermal conductivity and electrical resistivity of thin copper film simultaneously and is consistent with the experimental results. The thermal conductivity of the 50 nm thick copper layer is ~150 W m^-1 K^-1, which is much smaller than the bulk value (~400 W m^-1 K^-1) at room temperature. The experimental and modeling data are essential to address performance and reliability issues for future device and interconnect technologies