The application of micromachining techniques to the fabrication of highly integrated circuits working at high frequencies offers the means for reduction of weight and volume of the manufactured systems. These improvements, as well as the possible increase in electrical performance are crucial advantages that structures built with the aid of micromachining techniques offer.
The production of active devices and micromachined components like switches or filters on the same Si substrate wafer would provide the potential for further improvements. Important factors affecting the fabrication of active and micromachined components on the same wafer are temperature and chemical incompatibilities between the steps used for the production of active and passive devices. If possible at all, devices using this technique will only be produced in small numbers, mainly for sophisticated space and airborne applications.
However, it is not possible yet to tell whether an integration of this kind can be done or not, since during this practical training semester documented with this report, attention was merely kept on the production of passive devices.
Concerning the specific production steps given in the tables given in each chapter, it should be noted that the processes described are still under development. Therefore, changes to individual or groups of steps are likely to be made in the future. As stated by the research personnel of The Radiation Laboratory of the University of Michigan, further improvements of the flows could be done with state of the art micromachining technologies that are currently used in industries but are not available at the research facility mentioned above. E. g., with CMP (Chemical Mechanical Planarization) techniques available, the use and choice of sacrificial layers could be done differently, according to staff of the Radiation Laboratory.