3D Semiconductor Power Grid Layout for Heat Removal
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Solution Overview
Problem
Heat removal remains a significant challenge in 3D stacked integrated circuits and chips, particularly due to increased power density and high thermal resistance to heat sinks.
Innovation Solution
The implementation of advanced heat removal techniques, including the use of thermal vias, power and ground vias for thermal conduction, and the integration of thermally conductive materials in shallow trench isolation regions and pre-metal dielectric layers, to enhance heat transfer and reduce thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If 3D stacking of semiconductor devices is implemented to reduce wire lengths and improve transistor density, then transistor performance and functionality improve, but heat removal becomes significantly more difficult due to increased power density and high thermal resistance to heat sinks
Solution Approach 1:
The patent introduces liquid coolant flow paths that extend vertically through multiple device layers via through-silicon vias, transitioning from traditional 2D heat dissipation to 3D thermal management. This allows coolant to directly access heat-generating regions in stacked devices, effectively removing heat from internal layers that would otherwise have high thermal resistance to external heat sinks.
Solution Approach 2:
The patent uses liquid coolant as an intermediary substance to transfer heat from the stacked device layers to external heat sinks. The coolant flows through dedicated cooling channels and TSVs, acting as a thermal mediator that bridges the heat-generating transistor layers and the heat dissipation structures, enabling efficient heat removal without direct thermal contact between layers.
2Power
If multiple layers of transistors are stacked with increased power density, then functionality and performance improve, but thermal resistance to heat sinks increases making heat removal more difficult
Solution Approach 1:
The patent segments the heat removal path into multiple independent channels distributed across different device layers. Instead of relying on a single heat sink connection, the cooling system is divided into multiple parallel flow paths through TSVs and cooling channels, allowing heat to be removed from each layer independently. This segmentation reduces the thermal resistance burden on any single path while maintaining high power density.
Solution Approach 2:
The patent employs liquid coolant flow through hydraulically-connected channels and TSVs to actively remove heat from stacked device layers. The hydraulic system enables forced convection cooling, where pressurized coolant circulates through the 3D structure, efficiently extracting heat from high-power-density regions and transporting it to external heat sinks, thereby reducing effective thermal resistance.
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
These techniques effectively mitigate heat removal challenges in 3D ICs by improving thermal conductivity and reducing thermal resistance, thereby maintaining desirable temperature levels within the integrated circuits.
Implementation Method 1
Thermal vias have been suggested as techniques to transfer heat from stacked device layers to the heat sink
Implementation Method 2
Use of power and ground vias for thermal conduction in 3D-ICs has also been suggested
Implementation Method 3
Publications have suggested passing liquid coolant through multiple device layers of a 3D-IC to remove heat
Data Source
AI summary
A 3D device includes a first level including a first single crystal layer with control circuitry, where the control circuitry includes first single crystal transistors; a first metal layer atop first single crystal layer; a second metal layer atop the first metal layer; a third metal layer atop the second metal layer; second level (includes a plurality of second transistors, including metal gate) atop the third metal layer; a fourth metal layer above the one second level; a fifth metal layer atop the fourth metal layer, where the second level includes at least one first oxide layer overlaid by a transistor layer and then overlaid by a second oxide layer; a global power distribution grid including the fifth metal layer; a local power distribution grid, the thickness of the fifth metal layer is at least 50% greater than the thickness of the second metal layer, a layer deposited by ALD.