Deep Moat Seal Ring for IC Crack Prevention

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Solution Overview

Problem

Conventional seal rings in integrated circuits are ineffective in capturing cracks from the edge of the die, and their design becomes less desirable with reduced device size and multi-level metal technologies due to increased width and reduced via size.

Innovation Solution

The implementation of a deep moat extending substantially to the substrate and redundant vias in the seal ring to prevent crack propagation, with the deep moat's depth being a critical factor in enhancing crack prevention rather than its width, and redundant vias acting as physical barriers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional shallow moat is used in the seal ring, then the seal ring structure is simple, but it is ineffective in capturing cracks from the edge of the die

Engineering Contradiction:

Improvecrack prevention effectivenessVSAvoidseal ring structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the depth parameter of the moat from shallow (conventional) to deep (extending to or near the substrate), which fundamentally improves crack prevention effectiveness by creating a physical barrier that stops crack propagation from reaching the active area

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The seal ring is segmented into multiple functional components: the deep moat for crack termination, redundant vias for additional crack blocking, and metal layers for electrical function. This segmentation allows each component to specialize in its function while working together for overall reliability

Inventive Principle:

Principle #1Segmentation

2Area of moving object

If the device size is reduced, then the integration density increases, but the via size in the seal ring is also reduced making it less effective

Engineering Contradiction:

Improvedevice areaVSAvoidcrack prevention effectiveness

Core Design Contradiction:

Area of moving objectVSReliability

Solution Approach 1:

Instead of relying solely on via size (two-dimensional parameter) for crack prevention, the patent introduces depth as a third dimension by creating a deep moat that extends vertically to or near the substrate, providing effective crack termination even when via dimensions are reduced due to scaling

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Adaptability or versatility

If multiple metal layers are added to the seal ring, then the electrical functionality is enhanced, but the seal ring width increases making it less desirable

Engineering Contradiction:

Improveelectrical functionalityVSAvoidseal ring width

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

Different regions of the seal ring are assigned different functions: the deep moat region provides mechanical crack termination, while specific metal layer regions provide electrical connectivity. This local quality differentiation allows multi-level metal technologies to be implemented without increasing the overall seal ring width, as the vertical stacking of metal layers utilizes the depth dimension rather than expanding the horizontal footprint

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS8093719B1Seal ring for preventing crack propagation in integrated circuit devices

Publication Date: 2012.01.10 MONTEREY RESEARCH LLC

AI summary

In one embodiment, an integrated circuit device includes an active area encompassed by a seal ring. The seal ring may include a deep moat formed on an outer edge of the seal ring. The deep moat may have a depth that extends substantially to the substrate to prevent cracks from propagating into the active area. Alternatively or in addition, the seal ring may include redundant vias.