Extracting dielectric constant of low-k thin film material for interposer of 3-D multilayer packaging

Abstract

A simple methodology for extracting wideband dielectric constant of low-k thin film material has been demonstrated by fringing effect estimations measurements and field solving simulations of capacitor patterns. From the simulated fringing effects of the capacitors with arbitrary dielectric constants, we obtained the piecewise linear equations with two variables such as dielectric constant and fringing effect. And we determined the dielectric constant of low-k thin film material from the measured fringing effect of the capacitor on low-k material. We present the extracted dielectric constant up to 30GHz for a multiblock copolyimide (Q-VR-X0521; PI R&D Co., Ltd, Japan). Also we obtained the loss tangent of a multiblock copolyimide by using the same extracting methodology of dielectric constant. The extracted relative dielectric constant (epsivr) and loss tangent (tangamma) of the multiblock polyimide are from 3.9 to 3.2 and from 0.032 to 0.052 in frequency range from 50MHz to 30GHz, respectively.