Fabrication of a high-density MCM-D for a pixel detector system using a BCB/Cu technology
The MCM-D which is described here is a prototype for a pixel detector system for the planned Large Hadron Collider LHC at CERN, Geneva. The project is within the ATLAS experiment. A module consists of a sensor tile with an active area of 16.4 mm x 60.4mm, 16 read out chips, each serving 24x160 pixel unit cells, a module controller chip, an optical transceiver and the local signal interconnection and power distribution busses. The extremely high wiring density which is necessary to interconnect the read-out chips was achieved using a thin film Copper/Photo-BCB process above the pixel array. The bumping of the read out chips was done using electroplating PbSn. All dies are then attached by flip-chip assembly to the sensor diodes and the local busses. Focus of this paper is the detailed description of the technologies for the fabrication of this advanced MCM-D.