Wafer Seal Ring Structure for Dielectric Stack Protection
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Solution Overview
Problem
Damage to dielectric stacks occurs during wafer trimming and subsequent processing, leading to reduced yield of reliable semiconductor dies due to cracking, peeling, or delamination.
Innovation Solution
Incorporation of a seal ring layer surrounding the dielectric stack, which includes a protrusion extending into a trench in the substrate, to protect the dielectric stack from damage during trimming and subsequent processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wafer trimming is performed to remove defective edges, then productivity is improved, but the dielectric stack becomes susceptible to damage such as cracking and peeling
Solution Approach 1:
A seal ring layer is formed around the dielectric stack before wafer trimming occurs. This seal ring extends into a trench in the substrate and provides preliminary protection to the dielectric stack, preventing damage during the subsequent trimming process. The seal ring is deposited using atomic layer deposition (ALD) to ensure conformal coverage and strong adhesion.
Solution Approach 2:
The seal ring layer acts as a cushioning protective barrier that absorbs and distributes mechanical stresses before they can reach the dielectric stack during trimming. By being positioned between the trimming tool and the dielectric stack, the seal ring prevents direct contact and reduces the likelihood of cracking and peeling.
2Reliability
If the dielectric stack is made thicker to improve device performance, then device performance is improved, but the dielectric stack becomes more susceptible to damage during processing
Solution Approach 1:
The seal ring layer serves as an intermediary protective element between the external trimming environment and the dielectric stack. It mediates the mechanical stresses applied during trimming, distributing them away from the dielectric stack interfaces and preventing the initiation and propagation of cracks and peeling defects.
Solution Approach 2:
The seal ring provides localized protection specifically at the critical regions where the dielectric stack interfaces with the substrate and surrounding structures. By concentrating protective functionality at these vulnerable locations, the seal ring prevents damage without requiring changes to the overall dielectric stack design or performance characteristics.
Data Source
AI summary
The present disclosure relates to a semiconductor wafer structure including a semiconductor substrate and a plurality of semiconductor devices disposed along the semiconductor substrate. A dielectric stack including a plurality of dielectric layers is arranged over the semiconductor substrate. A conductive interconnect structure is within the dielectric stack. A seal ring layer is over the dielectric stack and laterally surrounds the dielectric stack along a first sidewall of the dielectric stack. The seal ring layer includes a first protrusion that extends into a first trench in the semiconductor substrate.