Graphite Oxide Thermal Interface for 3D IC Hot Spot Mitigation
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Solution Overview
Problem
Heat dissipation in Three-Dimensional Integrated Circuits (3DICs) is inefficient due to non-conductive materials like underfill and molding compounds, leading to localized temperature peaks (hot spots) that affect electrical performance and reliability.
Innovation Solution
A graphite oxide layer is applied as a heat spreader on the backside of semiconductor dies, providing effective thermal conductivity and mitigating hot spots by forming a thin, continuous or patterned layer that can be deposited at ambient temperature, enhancing heat dissipation and package performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If non-conductive materials like underfill and molding compounds are used between stacked dies, then mechanical support and structural integrity are improved, but thermal conductivity deteriorates causing heat trapping and hot spots
Solution Approach 1:
A graphite oxide layer is introduced as an intermediary thermal interface material between the bottom die and the heat spreader. This mediator layer has high thermal conductivity that enables efficient heat transfer from the die through the underfill and molding compound to the heat spreader, preventing heat trapping while maintaining the structural integrity provided by the non-conductive materials.
Solution Approach 2:
The patent uses a composite structure combining the non-conductive underfill and molding compounds with a graphite oxide layer. The graphite oxide layer acts as a thermally conductive pathway embedded within the thermally insulating composite package structure, creating a hybrid system that simultaneously provides mechanical support and efficient heat dissipation.
2Temperature
If heat is dissipated from inner dies through outer components, then thermal management is improved, but thermal resistance increases due to non-conductive materials in the heat path
Solution Approach 1:
The graphite oxide layer serves as a thermal mediator that bridges the thermal gap created by the non-conductive underfill and molding compounds. It provides a low-resistance thermal pathway that facilitates heat flow from the inner die through the package structure to the heat spreader, significantly reducing the overall thermal resistance of the heat dissipation path.
3Temperature
If a heat spreader is placed at the bottom of stacked dies, then heat dissipation capability is improved, but thermal resistance remains high due to intervening non-conductive materials
Solution Approach 1:
The graphite oxide layer is positioned as a thermal intermediary between the bottom die and the heat spreader, eliminating the thermal barrier effect of the non-conductive materials. It creates an efficient thermal coupling that allows the heat spreader to effectively draw heat away from the die, maximizing heat dissipation capability while minimizing 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
The graphite oxide layer significantly reduces thermal resistance by up to 50% and minimizes maximum temperature, thereby improving the performance and lifetime of 3DIC packages without increasing thermal budget or costs.
Implementation Method 1
The graphite oxide layer is disposed between the first die and the second die... providing effective thermal conductivity... significantly reduces thermal resistance
Data Source
AI summary
Semiconductor packages are provided. One of the semiconductor packages includes a first sub-package and a second sub-package. The first sub-package includes a first die, a graphite oxide layer on the first die and an encapsulant encapsulating the first die and the graphite oxide layer. The second sub-package is stacked on and electrically connected to the first sub-package, and includes a second die. The graphite oxide layer is disposed between the first die and the second die.