Inverse Hybrid Bonding for D2D/D2W Heterogeneous Integration With 20 μ m Pitch

Interconnect technologies are critical to meet the electrical and thermal requirements for high-performance heterogeneous integration systems. This work presents inverse hybrid bonding (IHB), a die-to-die/die-to-wafer (D2D/D2W) bonding technology for heterogeneous integration that enables optimized interconnect designs, process flexibility, and a batch scale “underfill” that employs a gas-phase deposition process for dielectric underfill. It is “inverse” because the metal-metal bonding occurs first; subsequently, the dielectric underfill improves the mechanical reliability. To demonstrate IHB, copper-copper (Cu-Cu) thermal compression bonding (TCB) is first used for electrical connectivity, followed by a vapor-phase deposition of metal organic framework (MOF) for dielectric underfill. A detailed study of the process parameters for the MOF deposition process and its effect on underfill coverage is presented. IHB is demonstrated on an electrical testbed that features simultaneous bonding of fine-pitch (20 μm) and large-pitch (100 μm) interconnects, demonstrating true heterogeneous integration. Compared to solder-based technologies and hybrid bonding, IHB is a simplified D2D/D2W process that enables interconnect design flexibility, a batch scale underfill process that is not constrained by legacy underfills, and reduced process sensitivity to surface particles and roughness.