Redistribution layers (RDLs) are widely applied for signal transmissions in advanced packages. Traditional redistribution layer (RDL) routers use only 90- and 135-degree turns for routing. With technological advances, routing in RDLs can be any obtuse angle, leading to larger routing solution spaces and shorter total wirelength. This paper proposes the first any-angle routing algorithm in the literature for multiple RDLs. We first give a novel global routing algorithm with accurate routing resource estimation. A multi-net access point adjustment method is then proposed based on dynamic programming and our partial net separation scheme. Finally, we develop an efficient tile routing algorithm to obtain valid routes with fixed access points. Experimental results show that our algorithm can achieve a 15.7% shorter wirelength compared with a traditional RDL router.

In modern heterogeneous integration technologies, chips with different processes and functionality are integrated into a package with high interconnection density and large I/O counts. Integrating multiple chips into a package may suffer from severe warpage problems caused by the mismatch in coefficients of thermal expansion between different manufacturing materials, leading to deformation and malfunction in the manufactured package. The industry is eager to find a solution for warpage optimization. This paper proposes the first warpage-aware floorplanning algorithm for heterogeneous integration. We first present an efficient qualitative warpage model for a multi-chip package structure based on Suhir's solution, more suitable for optimization than the time-consuming finite element analysis. Based on the transitive closure graph floorplan representation, we then propose three perturbations for simulated annealing to optimize the warpage more directly and can thus speed up the process. Finally, we develop a force-directed detailed floorplanning algorithm to further refine the solutions by utilizing the dead spaces. Experimental results demonstrate the effectiveness of our warpage model and algorithm.