Thermal expansion coefficients of low-k dielectric films from Fourier analysis of x-ray reflectivity

We determine the thermal expansion coefficient of a fluorinated poly(arylen e ether) low-k dielectric film using Fourier analysis of x-ray reflectivity data. The approach is similar to that used in Fourier analysis of x-ray ab sorption fine structure. The analysis compares two similar samples, or the same sample as an external parameter is varied, and determines the change i n film thickness. The analysis process is very accurate and depends on no a ssumed model. We determine a thermal expansion coefficient of 55 +/- 9 x 10 (-6) K-1 using this approach. (C) 2000 American Institute of Physics. [S002 1-8979(00)09913-8].