Heterogeneous Multi-Die Stitching Enabled by Fine-Pitch and Multi-Height Compressible Microinterconnects (CMIs)

A high-density and a highly scalable heterogeneous multi-die integration technology is presented in this paper. Central to this approach is a dense and face-to-face integration of heterogeneous ICs enabled by fine-pitch and multi-height compressible microinterconnects (CMIs) and stitch chips, which serve as the interface through which communication between active ICs occurs. Two separate testbeds are fabricated in order to characterize the proposed integration technology: the first testbed demonstrates the concatenated assembly of chips using the stitch chips with fine-pitch CMIs (in-line pitch of
$20~\mu \text{m}$
), while the second testbed demonstrates the fabrication of multi-height CMIs (75-, 55-, and 30-
$\mu \text{m}$
tall CMIs) on the same die. Electrical characterization, including resistance and S-parameters, and mechanical characterization of interconnects are reported as well as the assembly of the testbeds.