Measurements of thermal conductivity and the coefficient of thermal expansion for polysilicon thin films by using double-clamped beams

Abstract

In this paper, a test structure for simultaneously determining thermal conductivity and the coefficient of thermal expansion (CTE) of polysilicon thin film is proposed. The test structure consists of two double-clamped beams with different lengths. A theoretical model for extracting thermal conductivity and CTE based on electrothermal analysis and resonance frequency approach is developed. Both flat and buckled beams are considered in the theoretical model. The model is confirmed by finite element software ANSYS. The test structures are fabricated by surface micromachined fabrication process. Experiments are carried out in our atmosphere. Thermal conductivity and CTE of polysilicon thin film are obtained to be (29.96 ± 0.92) W · m · K−1 and (2.65 ± 0.03) × 10−6 K−1, respectively, with temperature ranging from 300–400 K.