On-Chip Heat Pipe for Interconnect Thermal Management
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Solution Overview
Problem
Increasing component densities in integrated circuits lead to higher power densities, necessitating enhanced thermal conductance, but trends in interconnect fabrication, such as increased interconnect levels and use of less dense dielectric materials, result in decreased thermal conductance through the interconnect region.
Innovation Solution
A heat pipe is fabricated within the interconnect region of the integrated circuit using planar fabrication methods, with a working fluid and wicking material to optimize heat transfer, and strengthening members for robustness, enhancing thermal conductivity between the substrate and the top surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If interconnect levels are increased to accommodate higher component densities, then component packing capability is improved, but thermal conductance through the interconnect region deteriorates
Solution Approach 1:
A heat pipe is introduced as an intermediary thermal management component within the interconnect region. The heat pipe includes a working fluid that undergoes phase change (evaporation at the bottom surface near heat-generating components, condensation at the top surface) to transfer heat vertically through the interconnect region, bypassing the thermal resistance of multiple interconnect levels and dielectric materials.
Solution Approach 2:
The heat pipe utilizes phase transitions of the working fluid (liquid to vapor at the evaporator section near components, vapor to liquid at the condenser section at the top surface) to achieve high-efficiency heat transfer. This phase change mechanism enables effective thermal conduction through the interconnect region despite increased interconnect levels and less dense dielectric materials.
2Object-affected harmful factors
If less dense dielectric materials are used to reduce capacitive coupling, then electrical interference is reduced, but thermal conductivity deteriorates
Solution Approach 1:
The heat pipe acts as a dedicated thermal conduction pathway that is independent of the dielectric material properties. By introducing this intermediary heat transfer mechanism, the system can use less dense dielectric materials for electrical isolation while the heat pipe compensates for the reduced thermal conductivity of the dielectric layer.
Solution Approach 2:
The heat pipe utilizes fluid dynamics and phase change of the working fluid to transfer heat, replacing reliance on solid dielectric thermal conduction. This hydraulic/pneumatic-based heat transfer mechanism achieves superior thermal conductivity compared to less dense dielectric materials while maintaining their electrical isolation properties.
3Reliability
If heat dissipation measures are enhanced to maintain temperature difference, then thermal management capability is improved, but device complexity increases
Solution Approach 1:
The heat pipe structure is integrated within the existing interconnect region, merging thermal management functionality with the electrical interconnect structure. This combined design achieves enhanced heat dissipation while utilizing the same vertical space and fabrication processes, thereby avoiding additional device complexity.
Solution Approach 2:
The heat pipe serves multiple functions: it provides thermal conduction pathways, acts as a structural element within the interconnect region, and enables both heat extraction from components and heat rejection at the top surface. This multi-functionality reduces the need for separate heat dissipation components, simplifying the overall device structure.
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
The heat pipe effectively increases thermal transfer efficiency, allowing for simpler and cheaper heat dissipation methods to maintain reliable operating temperatures, even with increased power densities.
Implementation Method 1
A heat pipe is fabricated in the interconnect region of an integrated circuit (IC)
Implementation Method 2
A working fluid in the heat pipe is selected to optimize the heat transfer rate in the operating temperature range of the IC
Implementation Method 3
A wicking material may be formed on the interior surface of the heat pipe to increase thermal transfer efficiency of the heat pipe
Implementation Method 4
The interior surface of the heat pipe may be reticulated to improve wicking action of the working fluid, and thus to increase thermal transfer efficiency of the heat pipe
Implementation Method 5
enhancing thermal conductivity between the substrate and the top surface
Data Source
AI summary
The density of components in integrated circuits (ICs) is increasing with time. The density of heat generated by the components is similarly increasing. Maintaining the temperature of the components at reliable operating levels requires increased thermal transfer rates from the components to the IC package exterior. Dielectric materials used in interconnect regions have lower thermal conductivity than silicon dioxide. This invention comprises a heat pipe located in the interconnect region of an IC to transfer heat generated by components in the IC substrate to metal plugs located on the top surface of the IC, where the heat is easily conducted to the exterior of the IC package. Refinements such as a wicking liner or reticulated inner surface will increase the thermal transfer efficiency of the heat pipe. Strengthening elements in the interior of the heat pipe will provide robustness to mechanical stress during IC manufacture.