A Novel Submicron Polymer Re-Distribution Layer Technology for Advanced InFO Packaging

From high-performance computing (HPC) applications such as Artificial Intelligence (A.I.) rising, advanced multi-chip packaging to integrate different functions could be a fast time-to-market and cost effective solution instead of SOC. Accordingly, more I/O die to die communications for advanced packaging is a need. To fulfill this demand, large number in registered routing lines between dies lead a constant drive for miniaturization for die to die Redistributed Layer (RDL) among industry. In this article, InFO Ultra-High-Density (UHD) RDL technology [1] is demonstrated, with RDL line-width down to submicron range (<;1um). This technology can empower the needs with industry trend. The InFO UHD RDL technology is characterized by electrical performances, e.g., via-chain continuity, RDL Comb/Meander Rs, line-to-line leakage current, and eventually reliability testing such as electro-migration (EM), stress migration (SM), breakdown voltage (Vbd), Time-Dependent-Dielectric Breakdown (TDDB), etc. After process optimization, the electrical test data demonstrate >99% yields from via-chain continuity, RDL Comb/Meander Rs and leakage current. Initial reliability testing shows good performance from EM, SM, Vbd, TDDB, etc. Package-level reliability test and results will also be addressed in this article. The potential challenges ahead will be discussed in terms of fundamental technical confinements as further scaling-down in RDL line-width and via, based on simulated and theoretical predictions, and possible approaches to resolve them.