Graded Metal Matrix Composite Layer for IC Heat Dissipation
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Solution Overview
Problem
The challenge of thermal management in integrated circuit devices is exacerbated by the thermal bottleneck of thermal interface materials and the thermomechanical stresses caused by metal films with high thermal conductivity but mismatched thermal expansion coefficients, which can lead to cracking and failure.
Innovation Solution
A metal matrix composite layer with a graded filler content is formed on the integrated circuit device, using additive manufacturing to deposit filler particles of varying sizes to match the thermal expansion of silicon, thereby reducing thermal interfacial resistance and stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If metal films with high thermal conductivity are deposited on the integrated circuit device, then thermal conductivity is improved, but thermomechanical stresses increase due to coefficient of thermal expansion mismatch
Solution Approach 1:
The patent applies local quality by creating a metal matrix composite layer where the filler material distribution varies through the thickness of the layer. The filler material concentration is higher near the integrated circuit device interface and decreases toward the outer surface, allowing the CTE to be locally optimized: closer to silicon CTE at the interface and transitioning to metal CTE at the outer surface.
Solution Approach 2:
The patent uses composite materials by combining metal matrix (such as copper or aluminum) with filler materials (such as diamond, silicon carbide, or aluminum nitride) to create a metal matrix composite layer. This composite structure enables simultaneous achievement of high thermal conductivity from the metal matrix and controlled CTE through the filler material distribution.
2Temperature
If thermal interface materials are used to transfer heat from the integrated circuit device, then heat transfer path is provided, but thermal bottleneck occurs due to lower thermal conductivity compared to silicon
Solution Approach 1:
The patent extracts the thermal interface material from the system by directly depositing the metal matrix composite layer on the backside of the integrated circuit device. This eliminates the thermal interface material layer that was previously necessary to transfer heat from the device to the heat dissipation structure.
Solution Approach 2:
The patent employs metal matrix composite materials that inherently possess high thermal conductivity exceeding that of silicon, enabling direct deposition on the device without requiring separate thermal interface materials. The composite structure provides both mechanical compliance and superior thermal transport properties.
3Temperature
If metal films are deposited using conventional deposition techniques, then high thermal conductivity is achieved, but sintering temperature exceeds 500 degrees Celsius which can damage the integrated circuit device
Solution Approach 1:
The patent changes the deposition parameters by using low-temperature deposition techniques such as electroplating, electroless plating, or sputtering that can form metal matrix composite layers at temperatures below 100 degrees Celsius. This preserves the integrity of the integrated circuit device while achieving the desired thermal conductivity.
Solution Approach 2:
The use of metal matrix composite materials allows for alternative deposition methods that are compatible with integrated circuit manufacturing. The composite nature of the material enables deposition processes that do not require high-temperature sintering, such as electrochemical deposition or physical vapor deposition followed by low-temperature consolidation.
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 enhances thermal conductivity while minimizing thermomechanical stresses, effectively managing heat dissipation without damaging the circuit.
Implementation Method 1
the thermal interface material provides a heat transfer path from the integrated circuit device(s) to the heat dissipation device
Implementation Method 2
coefficient of thermal expansion mismatch is minimized by positioning a first filler material particle constituent... closest to the backside surface of the integrated circuit device
Data Source
AI summary
An integrated circuit assembly may be fabricated to include an integrated circuit device having a backside surface and a metal matrix composite layer on the backside surface, wherein the metal matrix composite layer has a filler material disposed therein that has a graded content to reduce the coefficient of thermal expansion at the backside surface of the integrated circuit device. The filler material may have at least two filler material particle constituents having different particle diameters, wherein a first filler material particle constituent that has the smaller average diameter is closest to the backside surface of the integrated circuit device and wherein a second filler material constituent that has the larger average diameter is farthest from the backside surface of the integrated circuit device.