3D Semiconductor Device Thermal Management via Vertical Heat Paths
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Solution Overview
Problem
Three-dimensional integrated circuits (3D-ICs) face significant challenges in heat removal due to increased power density and high thermal resistance, particularly in stacked configurations where heat transfer from semiconductor layers to heat sinks is inefficient, often relying on ineffective thermal vias and insulating materials that impede heat conduction.
Innovation Solution
The implementation of a 3D semiconductor device structure with aligned transistors, thermally conductive materials, and enhanced power distribution networks, including thermal contacts and vias, to reduce thermal resistance and improve heat transfer efficiency, utilizing materials like copper, aluminum, and graphene for heat spreaders and conductive dielectrics to facilitate better heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple layers of transistors are stacked in 3D configuration, then transistor density and performance are improved, but heat removal becomes significantly more difficult due to increased power density and thermal resistance
Solution Approach 1:
The patent transitions from traditional 2D heat dissipation to 3D heat management by implementing vertical heat removal paths through stacked transistor layers. Heat is conducted upward through the transistor stack to heat sinks positioned on the top surface, utilizing the third dimension (vertical direction) to escape the heat accumulation problem inherent in planar configurations.
Solution Approach 2:
The patent introduces intermediate thermal management structures including heat spreader layers positioned between transistor stacks and heat sinks, and thermal interface materials that facilitate heat transfer across layer boundaries. These intermediary elements mediate the heat transfer process, improving thermal coupling and reducing thermal resistance at critical interfaces.
2Device complexity
If through-silicon vias are used to connect stacked device layers, then interlayer connectivity is achieved, but thermal resistance remains high and heat transfer efficiency is poor
Solution Approach 1:
The patent extracts the thermal management function from the electrical interconnect structure by implementing separate dedicated heat removal paths. Instead of relying on power and ground vias for heat conduction, the invention creates independent thermal conduction channels that specifically address heat transfer without being constrained by electrical connectivity requirements.
Solution Approach 2:
The patent makes power and ground vias multi-functional by designing them to serve both electrical connectivity and thermal conduction purposes simultaneously. These vias are configured to conduct both electrical current and heat, thereby reducing overall thermal resistance while maintaining necessary electrical interconnections between stacked layers.
3Reliability
If insulating materials are used for isolation in stacked configurations, then electrical isolation is achieved, but heat conduction is impeded due to high thermal resistance of these materials
Solution Approach 1:
The patent applies different material properties to different spatial locations within the device structure. Insulating materials are used in regions where electrical isolation is critical, while thermally conductive materials are strategically placed in heat removal paths and thermal interface regions. This localized differentiation allows simultaneous achievement of electrical isolation and effective heat conduction.
Solution Approach 2:
The patent employs composite material structures that combine electrical insulation with thermal conduction capabilities. These composite materials or material combinations allow heat to be conducted effectively while maintaining necessary electrical isolation between different functional regions of the stacked device.
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 effectively reduces thermal resistance, enabling more efficient heat removal from 3D-ICs, maintaining transistors within desirable temperature limits and supporting the integration of thermally conductive materials to enhance heat spreading and transfer across stacked layers.
Implementation Method 1
utilizing materials like copper, aluminum, and graphene for heat spreaders and conductive dielectrics to facilitate better heat dissipation
Implementation Method 2
utilizing materials like copper, aluminum, and graphene for heat spreaders and conductive dielectrics to facilitate better heat dissipation
Data Source
AI summary
A 3D semiconductor device, the device including: a first single crystal layer including a plurality of first transistors and a first metal layer, where the first metal layer includes interconnecting the first transistors forming, at least in part a plurality of logic gates; a plurality of second transistors overlaying, at least in part the first single crystal layer; a plurality of third transistors overlaying, at least in part the second transistors; a second metal layer overlaying, at least in part the third transistors; Input/Output pads to provide connection to external devices, a local power grid to distribute power to the plurality of logic gates, where the third transistors are aligned to the first transistors with less than 40 nm misalignment, where the first single crystal layer includes an Serializer/Deserializer (“SerDes”) structure connected to at least one of the Input/Output pads, where a memory cell includes at least one of the third transistors.