A Novel Low-Warpage Hyper RDL (HRDL) Interposer Enabled by Low Temperature Hybrid Bonding for Advanced Packaging Applications

To minimize warpage in the multilayer-RDL interposers, a novel approach called hyper RDL (HRDL) is proposed. The HRDL utilizes a low temperature hybrid bonding method to stack RDL layers, reducing the warpage by at least 20X as compared to the conventional semi-additive processes (SAP). The HRDL based on polymer-based hybrid bonding was demonstrated as low as 180 °C under atmosphere with a bonding strength of 47.83 kgf/cm2. Both the thermal cycling of 1000 cycles and the un-biased highly accelerated stress test of 168 hours showed less than 1.5% change in electrical resistance. The HRDL process flow is designed to ensure reasonable running costs without the need for polymer chemical mechanical planarization (CMP). This innovative approach leads to a low-warpage RDL interposer platform for advanced packaging applications.