Face-to-Face Photonic Quantum Computer Assembly for Cryogenic Interconnects
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Solution Overview
Problem
The integration of photonic integrated circuits (PICs) and electronic integrated circuits (EICs) in high-performance systems, such as communication and quantum computing systems, is hindered by complex and costly assembly processes, especially at cryogenic temperatures, where thermal and electrical performance are compromised due to high thermal resistance and signal attenuation.
Innovation Solution
A hybrid system is developed where PICs and EICs are bonded face-to-face within a single package, utilizing fusion or hybrid bonding, with optical and electrical connections, including optical fibers and printed circuit boards (PCBs), to minimize thermal resistance and signal delay, and accommodate cryogenic operations by matching coefficients of thermal expansion and improving thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If photonic integrated circuits and electronic integrated circuits are integrated in a hybrid system, then system performance is improved, but assembly complexity and cost increase
Solution Approach 1:
The patent merges photonic integrated circuits (PICs) and electronic integrated circuits (EICs) into a single hybrid package, bonding PIC dies and EIC dies face-to-face on a common substrate. This integration combines the advantages of both photonic and electronic systems while reducing interconnect lengths and improving signal transmission, directly addressing the technical contradiction by achieving system performance improvement through physical merging of the two circuit types.
Solution Approach 2:
The hybrid system is segmented into distinct functional modules: PIC dies for photonic operations, EIC dies for electronic control, and a common substrate for mechanical support and electrical interconnection. This segmentation allows each component to be optimized and tested independently before final assembly, reducing overall assembly complexity while maintaining system performance.
2Adaptability or versatility
If photonic integrated circuits and electronic integrated circuits are assembled at cryogenic temperatures, then quantum computing operations are enabled, but assembly difficulty increases
Solution Approach 1:
The patent performs preliminary thermal conditioning and bonding preparation at room temperature before cryogenic assembly. The common substrate and bonding interfaces are pre-characterized for thermal expansion mismatch, and bonding procedures are established at accessible temperatures. This preliminary action enables subsequent cryogenic operation while avoiding the extreme difficulty of performing all assembly steps directly at cryogenic temperatures.
Solution Approach 2:
The system utilizes parameter changes in material properties with temperature, specifically selecting materials with matched coefficients of thermal expansion (CTE) to maintain bonding integrity from room temperature through cryogenic operation. The bonding process parameters (temperature, pressure, time) are optimized as functions of the desired operating temperature range, enabling reliable assembly that withstands cryogenic conditions.
3Ease of manufacture
If traditional interconnect methods are used between photonic and electronic circuits, then manufacturing is simpler, but thermal resistance increases and signal attenuation worsens
Solution Approach 1:
The patent transitions from planar lateral interconnections to vertical three-dimensional interconnections by bonding PIC and EIC dies face-to-face. This dimensional change reduces interconnect length from millimeter-scale lateral paths to micrometer-scale vertical paths through the die stack, dramatically reducing thermal resistance and signal attenuation while maintaining manufacturing feasibility through standard bonding techniques.
Solution Approach 2:
The structure implements a nested arrangement where PIC and EIC dies are stacked vertically one on top of the other, with interconnects passing through the die stack. This nesting creates short, direct thermal and electrical pathways through the intermediate bonding layers, minimizing the thermal resistance and signal loss that would occur with traditional lateral routing while keeping the overall package compact.
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 approach reduces thermal gradients, enhances thermal conductivity, and improves the speed and power efficiency of the integrated circuits, enabling reliable operation at cryogenic temperatures below 10 K or 5 K, while also reducing manufacturing costs and complexity.
Implementation Method 1
The die stack may be bonded to the silicon substrate through fusion bonding
Implementation Method 2
the EIC die and the PIC die may be bonded face-to-face using fusion bonding or hybrid bonding
Implementation Method 3
the EIC die and the PIC die may be bonded face-to-face using fusion bonding or hybrid bonding
Data Source
AI summary
A device includes a die stack including a first die including a quantum circuit and a second die including an electronic circuit. The second die and the first die face each other. The device also includes a first interconnect between the quantum circuit and the electronic circuit and a second interconnect between the quantum circuit and the electronic circuit.