Segmented Die Seal Ring Air Gaps Block Crack Propagation
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Solution Overview
Problem
The die saw process in IC packaging induces excessive stress, leading to cracks that can damage the circuit structure by extending through the die seal ring during the fabrication of integrated circuits.
Innovation Solution
A die seal ring is designed with a substrate, a dielectric layer, and conductive layers, featuring first and second air gaps between the conductive portions and the dielectric layer, which are not connected, and optionally includes strengthening layers and materials like low-k materials and aluminum nitride, to prevent crack propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the die saw process is performed along the scribe line region, then the IC packaging fabrication can proceed, but excessive stress will cause cracks in the die that extend through the die seal ring and damage the circuit structure
Solution Approach 1:
The die seal ring is divided into multiple segments separated by air gaps, transforming it from a continuous structure into a segmented one. This segmentation allows the structure to accommodate stress during the die saw process while maintaining its protective function, preventing crack propagation through the seal ring.
Solution Approach 2:
Air gaps are strategically introduced at specific locations within the die seal ring structure, creating local variations in material density and mechanical properties. These localized air gap regions serve as stress relief zones that prevent crack propagation while maintaining the overall integrity and protective function of the die seal ring.
2Reliability
If air gaps are introduced in the die seal ring to prevent crack propagation, then circuit structure protection is improved, but the structural complexity increases
Solution Approach 1:
The air gap formation process is merged with the existing die seal ring fabrication process, utilizing the same deposition and etching steps to create both the seal ring structure and the protective air gaps simultaneously. This integration reduces the need for additional separate processing steps despite the increased structural complexity.
Data Source
AI summary
A method of manufacturing a die seal ring including the following steps is provided. A dielectric layer is formed on a substrate. Conductive layers stacked on the substrate are formed in the dielectric layer. Each of the conductive layers includes a first conductive portion and a second conductive portion. The second conductive portion is disposed on the first conductive portion. A width of the first conductive portion is smaller than a width of the second conductive portion. A first air gap is formed between a sidewall of the first conductive portion and the dielectric layer. A second air gap is formed between a sidewall of the second conductive portion and the dielectric layer.