Seal Ring Metal Pad Integration for Die Saw Peeling Prevention
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Solution Overview
Problem
Existing semiconductor integrated circuits (ICs) face issues with moisture ingress and ionic contamination, leading to degradation, threshold voltage instability, and die saw peeling during dicing processes, particularly in backside illuminated devices with low-k inter-metal dielectric films.
Innovation Solution
A method for fabricating semiconductor devices with a seal ring structure incorporating metal pads to prevent die saw peeling, involving the formation of frontside and backside metal pads coupled to the seal ring structure, which are integrated into the passivation layers to block die saw peeling effects and protect the IC from moisture and ionic contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a seal ring structure is used to protect IC from moisture and ionic contamination, then reliability is improved, but die saw peeling occurs during dicing processes
Solution Approach 1:
The patent employs a composite structure combining a seal ring made of dielectric material with a metal pad layer. This composite construction integrates the moisture-blocking properties of the seal ring with the mechanical strength and adhesion properties of the metal pad, thereby preventing both moisture ingress and die saw peeling during dicing processes.
Solution Approach 2:
The metal pad is strategically positioned at specific locations where the seal ring contacts the substrate, creating localized reinforcement zones. This local quality enhancement provides targeted mechanical support at critical stress points without compromising the overall seal integrity or adding excessive complexity to the structure.
2Productivity
If mechanical die saw is used for dicing, then productivity is improved, but layer peeling occurs due to cutting forces
Solution Approach 1:
The metal pad is formed and integrated into the seal ring structure before the dicing process. This preliminary action ensures that the reinforcement is already in place to counteract the mechanical stresses of die saw cutting, preventing layer peeling while maintaining high dicing productivity.
3Reliability
If low-k dielectric films are used in backside illuminated devices, then device performance is improved, but susceptibility to die saw peeling increases
Solution Approach 1:
The metal pad provides localized mechanical reinforcement specifically at the seal ring interfaces, which are the most vulnerable points to die saw peeling. This allows the use of low-k dielectric materials in the bulk structure for optimal device performance while providing targeted strength enhancement only where needed during dicing.
Solution Approach 2:
The combination of low-k dielectric seal ring material with the metal pad creates a composite structure that leverages the electrical performance benefits of low-k materials while compensating for their mechanical weakness through the adhesive and structural properties of the metal layer.
Data Source
AI summary
A method includes providing a substrate having a seal ring region and a circuit region, forming a seal ring structure over the seal ring region, forming a first frontside passivation layer above the seal ring structure, etching a frontside aperture in the first frontside passivation layer adjacent to an exterior portion of the seal ring structure, forming a frontside metal pad in the frontside aperture to couple the frontside metal pad to the exterior portion of the seal ring structure, forming a first backside passivation layer below the seal ring structure, etching a backside aperture in the first backside passivation layer adjacent to the exterior portion of the seal ring structure, and forming a backside metal pad in the backside aperture to couple the backside metal pad to the exterior portion of the seal ring structure. Semiconductor devices fabricated by such a method are also provided.