Large-Scale Cu Interconnection of Organic Substrate Materials Through Electroless Plating Technology

With the growing demand for high performance applications in semiconductor industry, direct Cu-to-Cu bonding has become the major trajectory for next generation IC packaging. However, even though the TSV-less packaging platform used in 2.3D integration is considered competitive for serving as alternative for 2.5D type package of Si interposer, the package warpage during high temperature bonding process by the CTE (coefficient of thermal expansion) mismatch between organic substrate and molded interposer chip of Si-based devices is still one of the major concern when packaging dimension become larger due to an increase of die size and the number of die mounted. Therefore, in this study, the feasibility of large size Cu interconnection achieved by microfluidic electroless interconnection (MELI) process under low temperature and without external pressure will be demonstrated on organic BT substrate materials where the mechanism behind flow parameters during the MELI process reaction will be further investigated. Also, the mechanical shear test for the reliability of Cu pillar joints were conducted, and it shows a phenomenal bonding strength of nearly 72 MPa comparable to commercial Sn-based solder joint.