Broadband, high-temperature dielectric properties measurements of thin substrates using open-ended probes

A metallized-ceramic probe has been designed for high-temperature broadband dielectric properties measurements. The probe has been used to make complex dielectric properties measurements over the frequency band from 500 MHz to 3 GHz, and up to temperatures as high as 1000/spl deg/C. We present results illustrating the use of this probe for broadband, high-temperature, dielectric properties measurements of thin samples and substrates. It is shown that by backing the material under test with a standard material of known dielectric constant such as air or metal, the complex permittivity of thin samples can be accurately measured. A 2D cylindrical FDTD code utilizing the symmetry of the probe was used for these thin-sample measurements. Results for thin (0.6 mm) alumina and sapphire samples for temperatures up to 800/spl deg/C are presented. This measurement method has important applications in the on-line characterization of semiconductor wafers.