Semiconductor Structure TSV Stress Balancing
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Solution Overview
Problem
Differences in thermal properties between substrates and conductive materials in 3D stacked integrated circuits lead to wafer warpage under thermal cycling conditions, affecting electrical performance and yield.
Innovation Solution
A semiconductor structure with a substrate featuring through holes filled with conductive and isolation materials, where the Young's modulus of the isolation material is smaller than that of the conductive material to balance stress, using materials like copper, tungsten, polysilicon, spin-on glass, and polyimide, and forming a multi-layer structure to offset thermal expansion mismatches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If through silicon vias (TSV) are used to create 3D stacking, then performance and functionality of integrated circuits are improved, but wafer warpage occurs under thermal cycling conditions due to thermal property differences between substrate and conductive materials
Solution Approach 1:
The patent changes the physical parameters of the materials used in TSV filling. Specifically, it uses conductive materials with appropriate thermal expansion coefficients and mechanical properties (such as copper, tungsten, or polysilicon) to match or complement the substrate properties, thereby reducing thermal stress and preventing wafer warpage during thermal cycling while maintaining electrical performance
Solution Approach 2:
The patent employs composite material structures in the TSV configuration, combining different materials with complementary properties. The TSV structure includes conductive materials for electrical connection paired with materials having specific mechanical properties to balance thermal stress, creating a composite system that achieves both electrical functionality and dimensional stability under thermal cycling conditions
2Reliability
If conductive material is filled in TSV to enable electrical connection, then electrical performance is improved, but stress imbalance causes wafer warpage
Solution Approach 1:
The patent carefully selects and controls the material parameters of conductive materials filled in TSV, including thermal expansion coefficient, Young's modulus, and coefficient of thermal conductivity. By matching these parameters to the substrate and surrounding materials, the patent achieves stress balance during thermal cycling while maintaining necessary electrical conductivity for device operation
Solution Approach 2:
The patent applies different material properties to different regions and layers within the TSV structure. The conductive material is selected with specific local properties (electrical conductivity) while the surrounding or adjacent materials have properties optimized for stress management, creating a locally optimized structure that balances electrical performance with mechanical stability
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 use of isolation materials with lower Young's modulus effectively balances stress from conductive materials, preventing warpage and enhancing the yield and reliability of semiconductor structures by maintaining structural integrity under thermal cycling.
Implementation Method 1
a Young's modulus of the isolation material is smaller than a Young's modulus of the conductive material to balance stress from the conductive material
Implementation Method 2
Differences in thermal properties between substrates and conductive materials lead to wafer warpage under thermal cycling conditions
Data Source
AI summary
A semiconductor structure includes a substrate, a first through hole disposed in the substrate and filled with conductive material, and a second through hole disposed in the substrate and filled with isolation material, which a Young's modulus of the isolation material is smaller than a Young's modulus of the conductive material to balance stress from the conductive material.