Thermal Conductivity Measurement of Low-k Dielectric Films: Effect of Porosity and Density

• Published in: Journal of electronic materials Vol. 43; no. 3; pp. 746 - 754
• Main Authors: Alam, M. T., Pulavarthy, R. A., Bielefeld, J., King, S. W., Haque, M. A.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.03.2014; Springer; Springer Nature B.V
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Conductivity; Cross-disciplinary physics: materials science; rheology; Density; Dielectric properties; Electronics and Microelectronics; Exact sciences and technology; Instrumentation; Materials Science; Measurement techniques; Optical and Electronic Materials; Physics; Porosity; Porous materials; granular materials; Solid State Physics; Specific materials; Thermal energy; dielectrics; Thermal conductivity; porous materials; low; thin films; Porous materials; Thermometry; Theoretical study; low-k dielectrics; Thin films; Electrical conductivity measurement; Modelling; Porosity; Non linear effect; Effective medium model; Model potential; Permittivity; Low k dielectric; Heat transfer
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-013-2949-5

The thermal conductivity of low-dielectric-constant (low- k ) SiOC:H and SiC:H thin films has been measured as a function of porosity using a heat transfer model based on a microfin geometry and infrared thermometry. Microscale specimens were patterned from blanket films, released from the substrate, and subsequently integrated with the experimental setup. Results show that the thermal conductivity of a dense specimen, 0.7 W/mK, can be reduced to as low as 0.1 W/mK by introducing 30% porosity into it. The measured thermal conductivity shows a nonlinear decrease with increasing porosity that approximately follows the porosity-weighted simple medium model for porous materials. Neither the differential effective medium nor the coherent potential model could predict the density dependence of the thermal conductivity. These results suggest that more careful consideration is required for application of generic porous materials modeling to low- k dielectrics.