Modified data analysis for thermal conductivity measurements of polycrystalline silicon microbridges using a steady state Joule heating technique

Abstract

Accurate knowledge of thermophysical properties is needed to predict and optimize the thermal performance of microsystems. Thermal conductivity is experimentally determined by measuring quantities such as voltage or temperature and then inferring a thermal conductivity from a thermal model. Thermal models used for data analysis contain inherent assumptions, and the resultant thermal conductivity value is sensitive to how well the actual experimental conditions match the model assumptions. In this paper, a modified data analysis procedure for the steady state Joule heating technique is presented that accounts for bond pad effects including thermal resistance, electrical resistance, and Joule heating. This new data analysis method is used to determine the thermal conductivity of polycrystalline silicon (polysilicon) microbridges fabricated using the Sandia National Laboratories SUMMiT V™ micromachining process over the temperature range of 77-350 K, with the value at 300 K being 71.7 ± 1.5 W/(m K). It is shown that making measurements on beams of multiple lengths is useful, if not essential, for inferring the correct thermal conductivity from steady state Joule heating measurements.

Measurement of in-plane thermal and electrical conductivities of thin film using a micro-beam sensor: A feasibility study using gold film

“…Hence, the configuration of the system, i.e., sizes and locations of the sensors and heaters, must be precisely measured because it is critically important for the accuracy of the measurement. Another method is to use the sample film both as a heater and a temperature detector [21][22][23][24][25]. With this method, the sample is prepared in a bridge-like structure suspended from the substrate.…”