TSV Substrate Mirror for High-Speed Optoelectronic Packaging
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Solution Overview
Problem
Traditional wire-bonding technology is inadequate for high-speed optoelectronic modules exceeding 10 Gbps, as it fails to effectively connect photonic chips with light-emitting or -receiving surfaces to optical fibers due to obstruction by the substrate, and lacks efficient electrical interconnects.
Innovation Solution
A TSV substrate with a mirror facet is used for flip-chip bonding of photonic and electronic dies, where the mirror facet forms an angle with the light-emitting/receiving surface, enabling optical coupling to optical fibers and providing electrical connections through vias and metal pillars, allowing for high-speed interconnects and improved heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional wire-bonding technology is used to connect photonic chips to PCB, then electrical connections can be established, but the substrate obstructs optical coupling between the light-emitting surface and optical fiber
Solution Approach 1:
The patent introduces a third dimension by bonding the photonic chip to the underside of the TSV substrate rather than placing it on the top surface. This dimensional change allows the light-emitting surface to face downward toward the reflective surface, enabling optical coupling through the substrate thickness while electrical connections are routed through vertical vias to the top surface.
Solution Approach 2:
The TSV substrate acts as an intermediary element that simultaneously provides both electrical interconnection (through metal-filled vias) and optical coupling (through the reflective surface). The substrate mediates between the photonic chip and external components, allowing both electrical and optical functions to coexist without mutual obstruction.
2Reliability
If wire-bonding is used for electrical interconnects, then connections can be made, but parasitics increase and high-speed performance beyond 10 Gbps is not achieved
Solution Approach 1:
The patent replaces the mechanical wire-bonding system with a direct flip-chip solder bump connection system. This substitution eliminates the long, flexible wire bonds that introduce parasitic inductance and resistance, replacing them with short, rigid solder bumps that provide low-parasitic electrical interconnects suitable for high-speed signals beyond 10 Gbps.
3Ease of operation
If photonic chip is bonded with light-emitting surface facing up, then optical access is straightforward, but flip-chip bonding cannot be performed and electrical interconnects are inefficient
Solution Approach 1:
The patent utilizes the third dimension (vertical orientation) by bonding the photonic chip to the underside of the TSV substrate. This allows the light-emitting surface to face downward for optimal optical coupling while the electrical connections route upward through vertical vias, resolving the conflict between optical access and bonding process requirements.
4Strength
If substrate is used to support photonic chip, then mechanical support is provided, but substrate obstructs optical path between light-emitting surface and optical fiber
Solution Approach 1:
The TSV substrate serves as a mediating structure that provides mechanical support through its rigid body while simultaneously enabling optical coupling. The reflective surface embedded in the substrate acts as an optical intermediary that redirects light from the photonic chip through the substrate thickness to external optical fibers, allowing the substrate to fulfill both mechanical and optical functions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables efficient optical and electrical interconnects, reducing parasitics and package size, suitable for high-speed applications beyond 10 Gbps, enhancing performance and heat dissipation in optoelectronic modules.
Implementation Method 1
the reflective surface forms an angle with the top surface, thereby enabling optical coupling between the top surface and an optical fiber placed in a direction that is substantially parallel to the top surface
Data Source
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AI summary
A packaged optoelectronic module is disclosed. The module includes a photonic chip (102) having a top surface and a first substrate (104) that includes a plurality of vias (108) and a reflective surface (110). The photonic chip (102) is flip-chip bonded to the first substrate (104) with the top surface facing the first substrate (102). The vias (108) facilitate electrical connections to the top surface, and the reflective surface (110) forms an angle with the top surface, thereby enabling optical coupling between the top surface and an optical fiber (114) placed in a direction that is substantially parallel to the top surface.