Flip-Chip Bonding of InP Die on SiN-Based TriPleX Carrier With Novel Laser Soldering

In this paper, we present a flip-chip bonding concept for InP die on SiN-based TriPleX carrier using laser soldering. The InP die and SiN-based TriPleX carrier include the metalization patterns for commonly used photonic integrated circuit reference designs. Two laser soldering schemes were investigated: (1) using a laser wavelength where silicon is highly transmissive (through-silicon laser soldering) and (2) using a laser wavelength where silicon is not transmissive (heat-conduction laser soldering). We demonstrated a 4.0 mm
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4.6 mm InP die with 58 electrical connections flip-chip bonded on a 16.0 mm
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8.0 mm SiN-based TriPleX carrier. Comparison experiments were carried out including solder reflow and shear force tests. Both schemes showed reliable electrical interconnects that meet MIL-STD 883 standards. Especially, the through-silicon soldering showed faster soldering time, lower power for solder reflows, and less thermal impact which is therefore preferred over heat-conduction soldering. This concept is promising for a high-density, reliable interconnect of hybrid packaging of InP on SiN-based photonic integrated circuits, in particular large photonic dies.