An investigation of the material and process parameters for thin-film MCM-D and MCM-L technologies up to 100GHz

The goal of the paper is to present the procedure of the extraction and separation of dielectric material parameters and metalization-related process properties up to mm-wave frequencies based on the measurements of general microstrip lines set of different line cross-sections and lengths. ne accuracy of the procedure has been tested up to 100GHz for the microstrip line cross-sections and dielectric materials used within the frame of the EU project LIPS aimed at the development of the low-cost packaging technologies at mm-wave frequencies. The technology set covers BCB thin-film MCM-D and thin laminate MCM-L technologies. The procedure allows the separation of complex permittivity of dielectric materials and metalization process related parameters without an exact modelling of these latter ones, which is very complicated, especially for composite metal build-up. Not only standard single layer substrate microstrip configurations can be analyzed but also more realistic in interconnect technology composite dielectric substrates and substrates with passivation layer configuration. In the first step of the procedure the complex propagation constants and complex characteristic impedances are extracted based on the probe-tip measurements of the microstrip lines with two different lenghts. In the second step these parameters are converted into the C, G, L, R equivalent elements of the corresponding distributed circuit model for quasi-TEM lines. These are related to the dielectric material and metalization-related process parameters by the use of a set of non-linear closed-form equations. The latter ones are solved by the use of Newton method. Hundreds of full-wave simulations have been done to choose, test and modify the closed-form equations as they impose a limit on the maximal achievable accuracy of the extraction procedure. This limit defined by a general rms accuracy of the extracted dielectric constants has been calculated using a data set from above mentioned full-wave simulations and is below 0.7% for the technology set and microstrip dimensions used within the project. Any measurements and process errors and tolerances are excluded because they are technology and measurement method dependent.