Evanescent microwave probe measurement of low-k dielectric films

An evanescent microwave probe (EMP) has been used to characterize low-k dielectric films grown on Si wafers at 2 GHz. Several families of low-k dielectric films with varying film thicknesses have been examined. The EMP signal (shift in resonant frequency) was found to scale with the “reduced electrical length,” defined as the film thickness/dielectric constant. The universal functional dependence derived from the experimental results is quantitatively consistent with the results of both analytical modeling and finite element simulations. These results demonstrate the unique capability of EMP to accurately characterize the application relevant parameter of low-k thin films.