Combination of MCM-C technology with MCM-D technology using photosensitive polymers

A combination of ceramic substrate technology with thin film processes will be presented. Thick film hybrids are used for the bottom layers and a thin film metallization layer is deposited on top for the redistribution of the signal lines. For the evaluation of this combined technology test samples of multilayer ceramic substrates were manufactured. Polymer films having a low dielectric constants and thin film copper were used to fabricate the high density interconnection layer. Photosensitive polymers were selected to reduce the number of processing steps for via formation. Photo-BCB is recommended for the dielectric layers because planarization of the ceramic substrate is the most critical issue for the high density metallization. For thicker photo-BCB films a tank development process was installed at TUB/Fraunhofer-IZM which has the unique feature that the development time is nearly independent of the layer thickness. The reliability of the substrates was proofed by thermal cycling.