Polylithic Integration of 2.5D and 3D Chiplets Using Interconnect Stitching

This paper explores polylithic integration of heterogeneous dice (chiplets) for high-density electronic systems. In this approach, stitch-chips are used to enable 2.5D integration by providing dense signal pathways between assembled 'anchor chips,' while surface-embedded chips provide 3D face-to-face electrical interconnection with corresponding anchor chips. Multi-height Compressible MicroInterconnects (CMIs) are used to enable low-loss and mechanically robust interfaces between the anchor chips and the stitch-chips as well as the surface-embedded chips. Fabrication and assembly of a testbed is reported and demonstrates robust interconnection. In an effort to characterize the CMIs and stitch-chip channels at high-frequency, electromagnetic simulations are carried out and demonstrate less than 0.6 dB insertion loss for 90 µm tall CMIs and 500 µm long channels on a fused silica stitch-chip.