Semiconductor Chip Seal Ring with Optical Inspection Area
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Solution Overview
Problem
Semiconductor chips, especially sensor chips, face damage during the dicing process due to cracks and contaminant infiltration, which can compromise the integrity of the seal ring and electronic circuitry, making it difficult to ensure the chips' functionality and integrity post-manufacturing.
Innovation Solution
A semiconductor chip design featuring a stack of insulating and metal layers with a seal ring and an optical inspection area to detect cracks, along with a crack stop area, which includes conductive structures to prevent crack propagation and ensure the seal ring's integrity, allowing for automated visual inspection to identify defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a seal ring is provided around the sensing element and electronic circuitry to protect against dicing damage, then the protection capability is improved, but cracks may still overcome the seal ring and damage the chip without being detected
Solution Approach 1:
An optical inspection area is introduced as an intermediary region between the seal ring and the chip edge. This intermediary area allows cracks that overcome the seal ring to be visually detected before reaching the sensitive components, serving as a warning system that bridges the gap between protection structure and defect detection capability.
Solution Approach 2:
The optical inspection area creates a visible copy or representation of crack propagation paths. By providing a dedicated area where cracks can be seen optically, the system creates a visual record of damage that would otherwise be hidden, enabling detection without direct inspection of the sealed components themselves.
2Productivity
If the wafer is diced to separate individual sensor chips, then productivity is improved, but cracks and contaminants may infiltrate and damage the sensing elements and circuitry
Solution Approach 1:
The seal ring is positioned and configured before the dicing process to preemptively counteract the harmful effects of dicing. The seal ring's protective structure is established in advance to resist crack propagation and contaminant infiltration that will occur during the subsequent dicing operation, allowing high-speed manufacturing without compromising component integrity.
Solution Approach 2:
The optical inspection area is prepared in advance of the dicing process to enable post-dicing verification. By having the inspection area ready before cutting, the system can quickly identify chips that sustained damage during dicing, allowing defective chips to be sorted out immediately and maintaining high manufacturing throughput while ensuring quality.
3Measurement precision
If automated optical inspection is implemented to detect cracks, then measurement precision is improved, but the complexity of the manufacturing process increases
Solution Approach 1:
The inspection function is extracted and concentrated into a specific optical inspection area rather than requiring inspection of the entire chip surface. By isolating the inspection function to a dedicated region with optimized optical access, the system achieves high detection precision while minimizing the complexity of the inspection apparatus, as only a limited area needs to be examined with high resolution.
Data Source
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AI summary
A sensor chip comprises a substrate (1) and a stack (2) of insulating layers arranged on the substrate. In a centre area (CA) of the sensor chip a sensing element (3) is arranged, as well as a circuit (21) in the stack (2) for electrically connecting the sensing element (3). Between the centre area (CA) and an edge (ED) of the sensor chip a seal ring (SR) and an optical inspection area (OI) are provided. The technique can also be applied with other types of semiconductor chips.