Thermoelectric Control for Stacked IC Thermal Management
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Solution Overview
Problem
Multi-tiered integrated circuits (ICs) face challenges with reduced thermal conductivity, leading to hot spots due to increased power density and poor heat dissipation, particularly with oxide layers and circuitry layout constraints, which existing solutions like heat conducting layers and Through Silicon Vias (TSVs) cannot effectively address without compromising performance or increasing manufacturing costs.
Innovation Solution
The implementation of a Thermoelectric (TE) device with P-N junctions, where the direction of current flow through the TE device allows for selective heating or cooling, using P-type and N-type elements and a control circuit to manage current density, facilitating heat transfer and uniform temperature maintenance across stacked ICs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If substrate thickness is increased to improve lateral thermal conductivity, then thermal conductivity is improved, but form factor is degraded and performance is negatively impacted
Solution Approach 1:
The patent transitions from lateral heat conduction (2D plane) to vertical heat conduction (3D depth) by implementing Through Silicon Vias that conduct heat from the first substrate through the second substrate to the heat dissipation structure, bypassing the limitation of thin substrate lateral conductivity
Solution Approach 2:
The patent introduces intermediate heat dissipation structures (heat sinks, heat spreaders) positioned between or around the stacked substrates that act as thermal mediators, conducting heat away from the hot spots without requiring increased substrate thickness
2Reliability
If oxide layers are used between stacked tiers for insulation, then electrical isolation is improved, but thermal conductivity is reduced
Solution Approach 1:
The patent introduces thermal interface materials or conductive adhesive layers as intermediate structures between the oxide insulation layers and the substrates, providing a thermal conduction pathway that does not compromise the electrical isolation function of the oxide layers
Solution Approach 2:
The patent segments the thermal management function from the electrical insulation function by using separate layers: oxide layers for electrical isolation and dedicated thermal pathways (TSVs, heat dissipation structures) for heat conduction, allowing each layer to optimize its specific function
3Temperature
If heat conducting layers are positioned between tiers to improve thermal conductivity, then thermal conductivity is improved, but inter-layer electrical connections are interfered with
Solution Approach 1:
The patent separates thermal conduction and electrical connection functions into different spatial domains: Through Silicon Vias provide vertical thermal conduction pathways, while electrical connections are established through separate conductive structures and inter-layer vias that do not interfere with the thermal management function
Solution Approach 2:
The patent uses thermal interface materials and heat dissipation structures as intermediaries that conduct heat without interfering with the electrical connection pathways, allowing both thermal and electrical functions to coexist without mutual interference
4Temperature
If TSVs are used to move heat from inner tier to surface tier, then heat dissipation is improved, but manufacturing complexity increases and location flexibility is reduced
Solution Approach 1:
The patent implements TSVs with multi-functionality: the same TSV structures serve both as electrical interconnections between tiers and as thermal conduction pathways to heat sinks, eliminating the need for separate dedicated thermal pathways and reducing manufacturing complexity
Solution Approach 2:
The patent merges the electrical connection function and thermal conduction function into a single integrated structure (TSVs with conductive material), allowing both functions to be achieved simultaneously through one manufacturing process rather than requiring separate structures
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 effectively manages thermal energy by either removing or adding heat, ensuring uniform temperature distribution, reducing energy consumption, and enabling operation in varying temperature environments, while also scavenging energy from temperature gradients to improve overall system efficiency.
Implementation Method 1
A thermoelectric (TE) device is provided within a stacked integrated circuit (IC) device. The TE device includes a pair of P-N junctions.
Data Source
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AI summary
Thermal conductivity in a stacked IC device (30) can be improved by constructing one or more active temperature control devices within the stacked IC device. In one embodiment, the control devices are thermal electric (TE) devices, such as Peltier devices. The TE devices (300) can then be selectively controlled to remove or add heat, as necessary, to maintain the stacked IC device within a defined temperature range. The active temperature control elements can be P-N junctions (301, 302) created in the stacked IC device and can serve to move the heat laterally and/or vertically, as desired.