Dielectric Guard Ring Layout for Through Via CTE Mismatch
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Solution Overview
Problem
The semiconductor industry faces challenges in achieving reliable and efficient integration of through vias in semiconductor dies due to significant differences in coefficients of thermal expansion (CTEs) between the through via materials and the semiconductor substrate, which can lead to performance deviations and reliability issues.
Innovation Solution
The implementation of a dielectric guard ring within the semiconductor substrate encircling the through via helps mitigate thermal expansion mismatches by providing a buffer with a CTE closer to that of the substrate, thereby improving the structural integrity and performance of the semiconductor die.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If through vias are formed in semiconductor substrate, then electrical connection between opposite sides is achieved, but thermal expansion mismatch causes performance deviation and reliability issues
Solution Approach 1:
A dielectric guard ring is introduced as an intermediary structure between the through via and the semiconductor substrate. This guard ring acts as a buffer that absorbs thermal expansion stress, protecting the through via connection from damage due to CTE mismatch between the via fill material and the substrate.
Solution Approach 2:
The dielectric guard ring is formed in advance during the fabrication process, creating a protective buffer zone around the through via before thermal cycling occurs during operation. This pre-established cushioning structure prevents thermal stress from directly affecting the through via connection.
2Productivity
If through vias are formed through semiconductor substrate, then integration density is improved, but structural integrity is compromised due to CTE differences
Solution Approach 1:
The dielectric guard ring serves as a mediator that maintains structural integrity while allowing the through via to provide electrical connection. The guard ring's dielectric material has thermal expansion properties that bridge the gap between the via fill material and substrate, preserving structural strength.
Solution Approach 2:
The structure employs composite material design with multiple layers including the dielectric guard ring, through via fill material, and semiconductor substrate. Each material is selected for its specific properties, creating a composite structure that achieves both high integration density and maintained structural integrity through proper material combination.
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 a dielectric guard ring effectively reduces the impact of CTE mismatches, enhancing the reliability and performance of semiconductor structures by absorbing heat and maintaining structural stability.
Implementation Method 1
significant differences in coefficients of thermal expansion (CTEs) between the through via materials and the semiconductor substrate
Implementation Method 2
absorbing heat and maintaining structural stability
Data Source
AI summary
In an embodiment, a method includes: forming a first opening in a semiconductor substrate, in a plan view the first opening having a ring shape; forming a dielectric guard ring in the first opening; forming an active device along a first surface of the semiconductor substrate; forming first metallization layers over the active device; forming a second opening through the semiconductor substrate, the second opening adjacent to the ring shape of the dielectric guard ring; forming a conductive through via in the second opening; and forming second metallization layers over the first metallization layers.