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2005
Conference Paper
Titel
Fabrication of Multichip-Modules for Pixel Detectors
Abstract
Advanced packaging technologies have been successfully adapted by the pixel detector industry for different applications. For example multi-channel detectors for particle detection consist of a semiconductor sensor substrate and several electronic front end read out chips, which process the detected signals. In this paper a MCM concept will be introduced where both are assembled in flip chip fashion to minimize the signal track length between the sensor pixel and the electronic chip. High resolution of the detector demands small pixel dimension and small solder joints in a tight pitch as well. The manufacture technology of pixel detector modules for the ATLAS Detector System of the Large Hadron Collider LHC at CERN, Geneva, will be discussed in details. For one module a total of 46080 pixel cells of the sensor substrate have to be joined to the I/Os of the front end chips by electroplated bumps with a diameter and spacing of only 25 microns. Yield is one of the most important parameters for the implementation of the MCM concept. A high yield manufacturing process therefore requires consistent electrical test on wafer level as well as on chip level. In this paper the potential of optical inspection and further process control will be described in detail. A reliable process technology, the assembly of electrical Known Good Dice (KGD) and an extensive use of inspection after each process step up to the development of a single chip repair technology are the basis of the high yield manufacture of pixel detector multi chip modules.