Efficient micro-bump assignment for RDL routing in 3DICs

For the signal connections between two adjacent dies in 3D ICs, the RDL routing from IO pads to micro-bumps plays an important role In this paper, given a set of micro-bumps and a set of connecting nets on the upper and lower RDLs between two adjacent dies, based on the testing of single-layer routing[7], an efficient algorithm including initial matching-based micro-bump assignment and rip-up-and-reroute-based reassignment is proposed to assign all the given nets on the micro-bumps for RDL routing. Compared with Kuan´s algorithmic for micro-bump assignment in using Yan´s single-layer routing algorithm [7] for RDL routing, the experimental results show that our proposed approach obtains shorter wirelength and reduces 73.7% of the CPU time to assign all the nets onto micro-bumps and guarantee 100% routability of single-layer RDL routing for five tested examples.