Fluidic-chemical characteristics of electroless copper deposition of ordered mass-fabricated pillars in a microchannel for chip packaging applications

The trend of chip-packaging in the semiconductor industry is pointing towards 3D integrated circuits and scaling down to attain devices with enhanced efficiency and performance. To overcome the reassimilat-ing challenges, we propose the usage of an electroless plated deposition layer to connect pillar bumps and create high-density interconnections. The substrates and pillar arrangements encompass our microchan-nel with the height of 50 mu m or 25 mu m where in between the electrolyte is forced with a superficial veloc-ity of 0.3 to 300 mm s-1 in our experiments. The results are compared to a numerical multi-physics model which simulates idealized plating conditions without any disruptions to characterize and quantify the different flow regimes and undesired side-effects. In the low-velocity regime, hydrogen bubbles can-not be dislodged and remain in the microchannel which is accompanied with the formation of extraneous deposition on the resist surface. The mid-velocity regime shows a good match to the simulation model and is considered as optimal plating condition. The chemical reaction slows down for high velocities.(c) 2023 Elsevier Ltd. All rights reserved.