Ultra Wide Micro Bumps Interconnection Matrix for High Energy Particle Detection: Process and Assembly

Micro pillars and micro bumps interconnections are considered as mature technology for 3-D integration and chip stacking. However, in the framework of high-energy particles detection as ATLAS Large Hadron Collider new tracker project at CERN, very large area array of dense interconnections with an aggressive specification of total thickness variation (TTV) of +/-2 mu m are required to grant successful detectors assembly process. This paper will first describe the test vehicle that has been designed on purpose for this study. The studies undertaken including lithography mapping, seed layer and electrochemical deposition (ECD) process will then be detailed introducing a model of anode intensity contribution to the overall TTV. To conclude, daisy chain electrical test results and yields after stacking using die-to-wafer approaches will be discussed with respects to process parameters.