Zigzag Seal Ring Structure for Stress-Resistant Device Dies
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Solution Overview
Problem
The formation of seal rings with long sections in wafer-level packaging leads to high stress, resulting in cracks and delamination in the seal rings and overlying passivation layers, compromising the integrity and reliability of integrated circuit devices.
Innovation Solution
The seal ring structure incorporates a zigzag pattern by bending metal sections to reduce stress, forming shorter segments that mitigate the stress-induced cracking and delamination issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If seal rings with long sections are formed in wafer-level packaging, then the seal ring can extend into multiple layers of integrated circuit structure, but high stress is generated resulting in cracks and delamination
Solution Approach 1:
The seal ring structure is divided into multiple segments arranged in a zigzag pattern rather than forming a single long continuous section. This segmentation breaks the long stress-prone section into shorter segments that are less susceptible to stress-induced cracking and delamination, while still maintaining the seal ring's protective function across multiple layers of the integrated circuit structure.
Solution Approach 2:
The seal ring incorporates a zigzag pattern with curved or angled sections instead of straight linear segments. This curvature in the seal ring geometry helps distribute and reduce stress concentrations that would otherwise occur in long straight sections, preventing cracks and delamination while maintaining structural integrity across multiple dielectric layers.
2Reliability
If seal rings extend into multiple layers of integrated circuit structure, then protection is provided to encircled circuits, but stress-induced cracking and delamination occur
Solution Approach 1:
The seal ring is segmented into multiple shorter sections arranged in a zigzag configuration, allowing it to extend through multiple dielectric layers while maintaining structural strength. Each segment is shorter and less prone to cracking, yet the collective segmented structure provides continuous protection around the periphery of the device die.
Solution Approach 2:
The seal ring geometry is changed from straight sections to a zigzag pattern with specific angular configurations. This parameter change in the seal ring's physical configuration reduces stress accumulation while maintaining its protective function, preventing delamination and cracking in the overlying passivation layers.
3Area of stationary object
If long seal ring sections are used, then the seal ring can encircle the device die periphery, but high stress generates cracks and delamination in passivation layers
Solution Approach 1:
The seal ring is divided into multiple segments forming a zigzag pattern that covers the device die periphery. This segmentation allows the seal ring to maintain broad coverage area for effective protection while each individual segment remains short enough to avoid generating harmful stress concentrations that cause cracking in the passivation layers.
Solution Approach 2:
The zigzag pattern introduces curved or angled sections in the seal ring geometry, which reduces stress concentrations compared to long straight sections. This curved geometry maintains the seal ring's ability to encircle and protect the device die periphery while minimizing stress-induced cracking in the overlying passivation structures.
Data Source
AI summary
A method includes forming a plurality of dielectric layers, forming a lower portion of a seal ring including a plurality of metal layers, each extending into one of the plurality of dielectric layers, depositing a first passivation layer over the plurality of dielectric layers, forming an opening in the first passivation layer, forming a via ring in the opening and physically contacting the lower portion of the seal ring, and forming a metal ring over the first passivation layer and joined to the via ring. The via ring and the metal ring form an upper portion of the seal ring. The metal ring includes an edge portion having a zigzag pattern. The method further includes forming a second passivation layer on the metal ring, and performing a singulation process to form a device die, with the seal ring being proximate edges of the device die.