Segmented Seal Ring Structure for IC Chip Area Optimization
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Solution Overview
Problem
The existing seal ring structures in semiconductor integrated circuit chip designs occupy a large width of the chip area, reducing the effective chip area for functional integrated circuits and increasing the cost per die, as they are needed to protect against moisture degradation, ionic contamination, and damage during dicing and packaging processes.
Innovation Solution
A seal ring structure is formed with a narrow first portion embedded in a first dielectric layer and a wide second portion extending into both the first and second dielectric layers, providing additional space for functional circuits while maintaining robust protection against cracks and contaminants, using a combination of dielectric layers with different constants and metallization layers to optimize chip area utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a seal ring structure is used to protect the IC from moisture degradation and ionic contamination, then the reliability of the integrated circuit is improved, but the effective chip area for functional integrated circuits is reduced
Solution Approach 1:
The seal ring structure is divided into two distinct portions: a first portion with a first width and a second portion with a second width greater than the first width. This segmentation allows different sections of the seal ring to serve different functions - the narrower first portion provides sufficient sealing protection while the wider second portion provides structural support and stress distribution, thereby reducing the total area occupied by the seal ring while maintaining protection effectiveness.
Solution Approach 2:
Different portions of the seal ring are given different widths based on local requirements. The first portion has a narrower width sufficient for sealing, while the second portion has a wider width for enhanced mechanical strength and stress distribution. This local differentiation optimizes the balance between protection and area utilization.
2Area of stationary object
If the chip area for each die is increased to gain more effective chip area, then the effective chip area for functional integrated circuits is improved, but the total die number within one wafer becomes less and the cost for each die becomes higher
Solution Approach 1:
By segmenting the seal ring into portions of different widths, the total area occupied by the seal ring is reduced. This allows either larger effective chip area for functional circuits or more dies per wafer, thereby improving productivity without sacrificing protection.
3Reliability
If a seal ring structure with large width is used to provide robust protection against cracks and contaminants, then the reliability is improved, but the manufacturing cost increases due to reduced die number per wafer
Solution Approach 1:
The seal ring is segmented into a first portion and a second portion with different widths. The wider second portion provides robust protection against cracks and contaminants where structural strength is needed, while the narrower first portion reduces overall material usage and chip area occupation, thereby lowering manufacturing costs.
Solution Approach 2:
Different widths are assigned to different portions of the seal ring based on local protection requirements. The wider second portion provides enhanced protection against mechanical stress and contaminants, while the narrower first portion optimizes area utilization, achieving cost-effective manufacturing.
Data Source
AI summary
A semiconductor device includes a substrate having a circuit region and a seal ring region. The seal ring region surrounds the circuit region. A seal ring structure is disposed over the seal ring region. The seal ring structure has a first portion and a second portion above the first portion. The first portion has a width W1, and the second portion has a width W2. The width W1 is less than the width W2.