Thermal Vias in Semiconductor Devices for Heat Dissipation
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Solution Overview
Problem
The increasing density of integrated circuits (ICs) in semiconductor devices leads to increased complexity in processing due to decreased feature sizes, which poses challenges in thermal management and heat dissipation.
Innovation Solution
The formation of thermal vias using thermally-conductive materials like diamond, aluminum nitride (AlN), and beryllium oxide (BeO) within the interlayer dielectric layers to enhance heat dissipation from transistors and gate electrodes, while minimizing coefficient of thermal expansion (CTE) mismatch with metal vias, thereby increasing via density and reducing thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the density of integrated circuits is increased to improve productivity, then the output per unit area is improved, but the thermal management complexity and heat dissipation difficulty increase
Solution Approach 1:
The patent segments the thermal management function by introducing separate thermal via structures distinct from electrical vias. These thermal vias are specifically designed to conduct heat away from transistor regions, dividing the thermal management task from other circuit functions and enabling targeted heat dissipation in high-density IC layouts.
Solution Approach 2:
The patent introduces thermal via structures as intermediary elements between the transistor heat sources and the substrate or heat sink. These thermal vias act as mediators that facilitate heat transfer without interfering with electrical signal paths, thereby managing thermal complexity independently of the electrical circuit design.
2Temperature
If thermal vias are formed using thermally-conductive materials to improve heat dissipation, then thermal resistance is reduced, but coefficient of thermal expansion mismatch with metal vias creates processing challenges
Solution Approach 1:
The patent changes the material parameter selection by choosing thermally-conductive materials with specific coefficient of thermal expansion properties that closely match those of surrounding dielectric layers and metal interconnects. This parameter matching reduces CTE mismatch stress during thermal cycling and processing, enabling reliable integration of thermal vias despite the use of specialized thermally-conductive materials.
Solution Approach 2:
The patent employs composite material structures where thermally-conductive materials are integrated with dielectric and metal layers to create a multi-material via system. This composite approach allows optimization of both thermal conductivity and CTE compatibility, combining the heat dissipation benefits of high-conductivity materials with the mechanical stability of CTE-matched materials in the same via structure.
3Temperature
If via density is increased to improve heat dissipation, then thermal resistance is reduced, but processing complexity increases due to decreased feature sizes
Solution Approach 1:
The patent segments the via formation process into distinct thermal via and electrical via formation steps. This segmentation allows thermal vias to be optimized for heat dissipation with larger, more robust dimensions suitable for high-density packaging, while electrical vias maintain their signal integrity requirements, thereby reducing overall processing complexity despite high via density.
Solution Approach 2:
The patent addresses processing complexity by transitioning from two-dimensional planar via layouts to three-dimensional via structures with varying cross-sections and depths. This dimensional approach allows thermal vias to achieve higher effective density and thermal conductance without proportionally increasing lithographic complexity, as the thermal performance is enhanced through vertical and radial geometry optimization rather than solely through lateral density increases.
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 effectively lowers thermal resistance and junction temperature in semiconductor devices, improving thermal management and allowing for higher via density without CTE-related issues, thus addressing the complexity of heat dissipation in densely packed ICs.
Implementation Method 1
The formation of thermal vias using thermally-conductive materials like diamond, aluminum nitride (AlN), and beryllium oxide (BeO) within the interlayer dielectric layers to enhance heat dissipation from transistors and gate electrodes
Implementation Method 2
minimizing coefficient of thermal expansion (CTE) mismatch with metal vias
Data Source
AI summary
A device includes plural semiconductor fins, a gate structure, an interlayer dielectric (ILD) layer, and an isolation dielectric. The gate structure is across the semiconductor fins. The ILD surrounds the gate structure. The isolation dielectric is at least between the semiconductor fins and has a thermal conductivity greater than a thermal conductivity of the ILD layer.