Photonics Package Cavity Bridge for High-Density EIC Routing
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Solution Overview
Problem
The development of high-performance optical transceivers faces challenges in routing congestion due to smaller electronic integrated circuits (EICs) reducing the footprint on the substrate, limiting the number of I/O and power lines that can be accessed, forcing tradeoffs between power, bandwidth, cost, and size.
Innovation Solution
The implementation of photonics package architectures that leverage in-cavity interconnects, such as cavity bridges with through-hole vias, to enable tight-pitch, high-density routing, allowing for closer spacing of routing lines and increased access to power and I/O lines without increasing the size of the EIC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If smaller EICs are used to reduce power requirements and package size, then power consumption and package size are reduced, but routing congestion increases and the number of accessible I/O and power lines decreases
Solution Approach 1:
The patent introduces a cavity bridge structure that extends vertically beneath the EIC, utilizing the third dimension (z-axis) to provide additional routing space. Through-hole vias penetrate the cavity bridge substrate, enabling I/O and power lines to access the EIC from below rather than only from the top plane, effectively adding a vertical routing dimension to relieve congestion
Solution Approach 2:
The cavity bridge structure is nested within the package substrate, with the bridge substrate containing through-hole vias that pass completely through it. This nested configuration allows multiple routing layers and interconnect structures to be stacked vertically, maximizing space utilization beneath the EIC without increasing the overall package footprint
2Area of moving object
If smaller EICs are used to reduce package size, then package size is reduced, but the number of accessible I/O and power lines decreases
Solution Approach 1:
The cavity bridge enables I/O and power lines to be routed through the vertical dimension via through-hole vias beneath the EIC. This allows a greater quantity of connections to be achieved without increasing the horizontal package area, as connections are made in the vertical space below the EIC rather than competing for limited top-plane real estate
Solution Approach 2:
The interconnect structure is segmented into multiple functional zones: top-side I/O access points, cavity bridge routing layer with through-hole vias, and bottom-side access points. This segmentation allows I/O and power lines to be distributed across different vertical levels and spatial zones, increasing the total number of accessible lines within the same package footprint
3Quantity of substance
If tighter pitch routing is implemented in the cavity bridge, then routing density is increased, but manufacturing precision requirements increase
Solution Approach 1:
The cavity bridge is implemented as a separate substrate with its own optimized interconnect parameters, including via diameter, pitch, and trace width, that are tailored for high-density routing. By decoupling the cavity bridge design from the main package substrate, each can be manufactured with parameters optimized for their specific routing density requirements, managing precision demands through parameter specialization
Data Source
AI summary
In one embodiment, an integrated circuit package includes a package substrate with a cavity, an integrated circuit device, a bridge, a photonic integrated circuit (PIC), and an electronic integrated circuit (EIC). The integrated circuit device is electrically coupled to the package substrate. The bridge and the PIC are in the cavity of the package substrate, and the bridge is electrically coupled to the package substrate. The EIC is above, and electrically coupled to, the bridge and the PIC.