Step Seal Ring Layout for Thermal-Mismatch Corner Bonding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The integration of multiple device dies in a semiconductor package, such as System on Integrate Chip (SoIC), often results in cracking and non-bonding issues at the corners due to thermal expansion mismatch between different materials, particularly at the interface of seal rings.
Innovation Solution
The implementation of a stepped seal ring structure, where the outer seal ring lacks an upper portion or has a narrower upper portion than the inner seal ring, made of materials with different thermal expansion coefficients, reduces stress and prevents cracking and non-bonding at the corners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple device dies are integrated in the same package to achieve more functions, then device performance and functionality are improved, but cracking and non-bonding issues occur at the corners due to thermal expansion mismatch
Solution Approach 1:
The seal ring is segmented into two distinct portions: a first seal ring portion and a second seal ring portion. Each portion is made of different materials with different thermal expansion coefficients, allowing the structure to accommodate thermal stresses from multiple device dies with different technologies while maintaining bonding reliability at the corners
Solution Approach 2:
Different portions of the seal ring have different material compositions tailored to their specific locations. The first seal ring portion has a first material composition while the second seal ring portion has a second material composition, enabling each region to locally adapt to the thermal expansion characteristics of adjacent device dies, thereby preventing cracking and non-bonding issues
2Reliability
If seal rings are made of materials with different thermal expansion coefficients to accommodate thermal mismatch, then stress-induced cracking is reduced, but the structure becomes more complex
Solution Approach 1:
The seal ring is divided into two functional segments with different material compositions. This segmentation allows each portion to be optimized for its specific thermal environment while maintaining a relatively simple overall structure that integrates seamlessly into the package
Solution Approach 2:
The seal ring utilizes composite material construction with at least two different materials having different thermal expansion coefficients. This composite approach enables the seal ring to handle thermal expansion mismatch from multiple device dies while maintaining structural integrity and avoiding cracking, without requiring overly complex geometric designs
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 design effectively minimizes stress-induced cracking and non-bonding issues by utilizing seal rings with varying thermal expansion coefficients, ensuring reliable bonding and improved package integrity.
Implementation Method 1
cracking and non-bonding issues at the corners due to thermal expansion mismatch between different materials, particularly at the interface of seal rings
Data Source
AI summary
A method includes forming a plurality of dielectric layers over a semiconductor substrate, forming a plurality of metal lines and vias in the plurality of dielectric layers, forming a lower portion of an inner seal ring and a lower portion of an outer seal ring extending into the plurality of dielectric layers, depositing a first dielectric layer over the plurality of metal lines and vias, and etching the first dielectric layer to form an opening penetrating through the first dielectric layer. After the first dielectric layer is etched, a top surface of the lower portion of the inner seal ring is exposed, and an entire topmost surface of the lower portion of the outer seal ring is in contact with a bottom surface of the first dielectric layer. An upper portion of the inner seal ring is then formed to extend into the opening and to join the lower portion of the inner seal ring. A second dielectric layer is deposited to cover the upper portion of the inner seal ring.