Signal-Grounded Seal Ring for Coupling Noise Reduction
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Solution Overview
Problem
Conventional methods for reducing cross talk between signal lines in integrated circuits are inadequate due to significant space consumption and increased complexity, which limits their effectiveness in high-density circuit designs, especially in deep-sub-micron technologies and stacked die configurations.
Innovation Solution
A semiconductor structure featuring a signal-grounded seal ring with metal lines and vias surrounding the circuit region, which encloses signal lines to reduce cross talk, and can be extended to divide circuits into sub-circuits, using dual damascene processes for formation and connected to an adjustable potential for enhanced noise isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional isolation structures (grounded metal lines or planes) are used to reduce cross talk, then cross talk isolation effect is improved, but space consumption increases significantly
Solution Approach 1:
The seal ring structure embeds multiple metal layers within the existing interconnect stack, nesting the isolation function within the vertical space already allocated for signal routing. This allows cross-talk reduction without expanding the lateral footprint of the circuit.
Solution Approach 2:
The invention transitions from planar isolation structures to a three-dimensional seal ring configuration that utilizes vertical stacking of metal layers. By moving the isolation function into the vertical dimension, the solution reduces lateral space consumption while maintaining effective electromagnetic shielding.
2Object-affected harmful factors
If cable-like enclosed structures with multiple metal layers are used for better isolation, then cross talk insulation effect is improved, but device complexity increases
Solution Approach 1:
The seal ring structure serves multiple functions simultaneously: it provides cross-talk isolation, acts as an electromagnetic shield, and can be integrated with existing interconnect layers without requiring separate dedicated isolation structures. This multi-functionality reduces overall device complexity.
Solution Approach 2:
The invention combines the isolation function with the existing interconnect metal layers by forming seal rings using the same metal deposition and patterning processes already employed for signal routing. This merging eliminates the need for separate isolation structure fabrication steps.
3Object-affected harmful factors
If grounded metal structures are added to reduce cross talk, then noise isolation is improved, but manufacturing complexity increases
Solution Approach 1:
The seal ring structures are formed using the same dual damascene metal deposition and patterning processes already employed for creating interconnect lines. By merging the isolation structure fabrication with existing manufacturing steps, no additional process complexity is introduced.
Solution Approach 2:
The seal ring structures automatically provide grounding through their connection to existing ground planes and interconnect layers, eliminating the need for separate grounding structure fabrication. The structure serves itself by utilizing available ground paths in the interconnect stack.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The signal-grounded seal ring effectively reduces coupling noise between chips and sub-circuits, minimizing signal delays and logic errors, while being compatible with standard manufacturing processes without additional cost or complexity.
Implementation Method 1
A signal line is enclosed in a cylinder-like signal-grounded seal ring. The cross talk between signal lines inside the seal ring and signal lines outside is effectively reduced.
Implementation Method 2
The respective electromagnetic fields generated by the signal lines 4 and 6 are partially insulated by signal-grounded lines 2 and thus the cross talk is reduced.
Data Source
AI summary
A semiconductor structure for preventing coupling noise in integrated circuits and a method of forming the same are provided. The semiconductor structure includes a signal-grounded seal ring. The seal ring includes a plurality of metal lines, each in a respective metal layer and surrounding a circuit region of the semiconductor chip, a plurality of vias connecting respective metal lines, and a plurality of dielectric layers isolating each metal layer from any other metal layers. The seal ring may further include additional seal rings formed inside or outside the seal ring. The semiconductor structure may include laser fuses and protective rings. The protective rings are preferably signal grounded. Cross talk between sub circuits in a chip can be reduced by forming a seal ring extension between the sub circuits.