Measurements of the electrical properties of dielectric substrates and resistive films in the frequency range 120-180 GHz

Abstract

A measurement technique has been devised for measuring the electrical properties of both thin (<1 mm) dielectric substrates and resistive films in the frequency range 120 to 180 GHz. The method uses dielectric waveguides to focus the radiation onto one of the surfaces of the dielectric and to collect the transmitted power on the other surface. From the ratio of the transmitted to incident powers taken over a frequency range, the dielectric constant can be measured. In addition, measurements of resistive films on dielectric substrates have been made where the value of the sheet resistance at microwave frequencies can be established. This has proved useful for measuring highly doped layers in semiconductor substrates and for making attenuating resistive films. For instance, it can be used to measure the properties of conducting buried layers in semiconductor substrates where most other techniques cannot be used directly. The paper concludes with some comments on the wider implications of the technique at different frequencies. (4 pages)