Segmented Guard Ring Structure for Double-Sided IC Crack Detection
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Solution Overview
Problem
Double-sided integrated circuit structures face challenges such as mechanical cracking and electrostatic discharge during fabrication, particularly due to the weakness of the active device layer located between the frontside and backside layers, and the lack of effective electrical isolation across this layer.
Innovation Solution
The implementation of a double-sided integrated circuit structure with an electrostatic guard ring and crack stop mechanisms, including a metal body with discrete segments and vias that interconnect across the active device layer, providing mechanical reinforcement and electrical isolation to prevent crack propagation and electrostatic discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a continuous metal body is formed across the active device layer to provide electrical connectivity, then electrical connection between sense pads is improved, but mechanical cracking and electrostatic discharge risks increase due to stress concentration and lack of isolation
Solution Approach 1:
The metal body is divided into multiple discrete segments rather than forming a continuous structure. These segments are distributed across the active device layer and interconnected through vias, creating a segmented conductive network that maintains electrical connectivity while reducing stress concentration and preventing crack propagation paths.
Solution Approach 2:
Different regions of the structure have different properties: the metal segments provide electrical connectivity in specific locations, while the dielectric material between segments provides mechanical support and electrical isolation. The via structures provide localized connections where needed, creating a non-uniform but optimized structure that balances conductivity and mechanical integrity.
2Productivity
If the active device layer is made thinner to increase transistor density, then device integration is improved, but mechanical strength and resistance to cracking deteriorate
Solution Approach 1:
The metal body is segmented into discrete portions that can be distributed across the thin active device layer without requiring long continuous spans. This segmentation allows the structure to accommodate thinner device layers while maintaining mechanical integrity, as each segment is independently supported by the underlying and overlying dielectric layers.
Solution Approach 2:
The electrical connectivity is achieved not through lateral continuity within the thin active device layer, but through vertical connections via vias that extend through the dielectric layers. This dimensional transition from lateral to vertical connectivity allows thin active device layers to maintain both mechanical strength and electrical functionality.
3Adaptability or versatility
If more metal layers and traces are added to increase circuit complexity, then functional capability is improved, but manufacturing precision requirements and fabrication difficulty increase
Solution Approach 1:
The metal body is formed as segmented structures that can be created using standard photolithography and deposition processes without requiring complex continuous patterning. The discrete segments are simpler to manufacture with precise alignment than continuous metal traces, as they tolerate greater dimensional variations and alignment tolerances.
Solution Approach 2:
The segmented metal body structure serves multiple functions simultaneously: it provides electrical connectivity between sense pads, acts as an electrostatic guard ring to prevent discharge, and functions as a mechanical reinforcement structure. This multi-functionality reduces the need for additional specialized structures, simplifying the overall fabrication process.
Data Source
AI summary
A structure includes a semiconductor substrate; a plurality of first dielectric layers at a top side of the substrate; an active device layer at a top side of the first layers; a plurality of second dielectric layers at a top side of the device layer; first and second sense pads; and a metal body that electrically connects the pads. The metal body includes a first portion that is embedded in the first layers, made of a first plurality of discrete segments; a second portion that is embedded in the second layers, made of a second plurality of discrete segments, of which a first is electrically connected to the first pad and a second is electrically connected to the second pad; and a plurality of vias that interconnect the first and second portions. Breaking any of the vias reduces the electrical connectivity between the pads.