TSV Ring Structure Mitigates Thermal Stress in Semiconductor Devices
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Solution Overview
Problem
The large mismatch in coefficients of thermal expansion between copper TSV electrodes and silicon substrates in semiconductor devices leads to thermal stress, causing mechanical instability, delamination, and decreased performance due to cracking and delamination issues.
Innovation Solution
A ring structure is introduced around the TSV electrode on the substrate's back side, which can be either conductive or insulating, and is either physically connected to or separate from the TSV electrode, to mitigate thermal stress by either releasing it or shifting the interface to a region of lower stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If copper TSV electrodes are used to provide electrical connections, then electrical conductivity is improved, but thermal stress increases due to CTE mismatch with silicon substrate
Solution Approach 1:
A ring structure is introduced as an intermediary element between the copper TSV electrode and the silicon substrate. This ring structure acts as a stress buffer that mediates the thermal expansion mismatch, absorbing thermal stress while allowing the copper electrode to maintain its electrical conductivity function without direct mechanical coupling to the substrate.
Solution Approach 2:
The invention changes the physical parameters of the interface region by introducing a ring structure with specific geometric parameters (radius, thickness) and material properties. This modifies the stress distribution parameters in the vicinity of the TSV electrode, transforming the stress field to reduce peak stresses and prevent delamination.
2Reliability
If copper TSV electrodes are used for interconnection, then electrical connection performance is improved, but mechanical stability deteriorates due to thermal stress-induced delamination and cracking
Solution Approach 1:
The ring structure is positioned beforehand around the TSV electrode to provide cushioning protection against thermal stress. This preventive structure absorbs and distributes thermal stresses before they can cause delamination or cracking, thereby protecting the mechanical stability of the electrical connection system.
Solution Approach 2:
The invention creates a composite structure consisting of the copper TSV electrode, the ring structure (made of different material), and the silicon substrate. This composite configuration combines materials with different thermal and mechanical properties to achieve both good electrical conductivity and enhanced mechanical stability through stress distribution.
3Stress or pressure
If a ring structure is added around the TSV electrode, then thermal stress is reduced, but device complexity increases
Solution Approach 1:
The stress management function is segmented from the main TSV electrode structure by introducing a separate ring structure. This segmentation allows the ring to independently handle thermal stress while the TSV electrode maintains its electrical connection function, achieving stress reduction without significantly complicating the overall device architecture.
Solution Approach 2:
The ring structure introduces local quality changes only in the critical stress concentration region around the TSV electrode, rather than modifying the entire device structure. This localized approach reduces thermal stress effectively while minimizing the increase in overall device complexity.
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 ring structure effectively reduces thermal stress between the TSV electrode and the substrate, preventing delamination and cracking, thereby enhancing the mechanical stability and performance of semiconductor devices.
Implementation Method 1
due to a large mismatch of coefficients of thermal expansion (CTEs) between copper, or other conductive material of the TSV electrode, and silicon of a substrate surrounding the TSV electrode, structural instability and some defects may occur owing to a thermal stress induced by the large mismatch of CTEs
Data Source
AI summary
A semiconductor device with a ring structure surrounding a through silicon via (TSV) electrode and a method for forming the same are disclosed. The method includes receiving a substrate including a back side and a front side having a conductor thereon, forming a via hole in the substrate and exposing the conductor, forming a groove extending from the back side into the substrate and surrounding the via hole, forming a first material layer in the via hole, and forming a second material layer in the groove. The groove filled with the second material layer forms the ring structure, while the via hole filled with the first material layer forms the TSV electrode.