Backside Metal Line Layout for FinFET ESD Reliability
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Solution Overview
Problem
Existing electrostatic discharge (ESD) prevention devices in semiconductor manufacturing are inadequate for newer technology generations, as they can fail due to breakdown of backside dielectric layers and density loading effects during chemical mechanical polishing, especially when backside metal lines are not properly placed.
Innovation Solution
The implementation of a semiconductor structure with ESD protection devices, including a wide active region for ESD diodes and specific placement rules for backside metal lines to ensure proper function, where the ESD diodes have a floating gate structure and sacrificial layers that are not selectively removed, and backside metal lines are spaced to avoid shorts and failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If ESD prevention devices are scaled down to match smaller IC dimensions, then IC size and power consumption are reduced, but ESD device functionality and reliability deteriorate
Solution Approach 1:
The patent applies local quality by creating distinct ESD protection regions with specific structural characteristics different from logic regions. The ESD devices are designed with wider active regions and specific implantation patterns tailored to their protective function, while other regions maintain their original design rules. This localized differentiation allows ESD devices to maintain effectiveness even as overall IC dimensions are scaled down.
Solution Approach 2:
The patent introduces backside metal lines as an additional dimensional solution for ESD protection. Instead of relying solely on planar scaling, the invention utilizes the vertical dimension by implementing metal interconnects on the backside of the substrate, creating a three-dimensional interconnect architecture that provides ESD protection pathways independent of front-side scaling constraints.
2Adaptability or versatility
If backside power rails are introduced to support increased functionality, then IC functional capacity is enhanced, but device failures occur due to improper metal line placement
Solution Approach 1:
The patent applies preliminary action by establishing design rules and placement constraints for backside metal lines before fabrication. Specific spacing requirements and avoidance zones are predefined to prevent metal lines from being placed in locations that would cause ESD device failures. This proactive approach ensures that as IC functionality is enhanced with additional backside power rails, the reliability of ESD protection is maintained through pre-planned preventive measures.
3Ease of manufacture
If existing ESD prevention devices are used in new technology generations, then manufacturing consistency is maintained, but ESD protection effectiveness is insufficient
Solution Approach 1:
The patent applies parameter changes by modifying key structural parameters of ESD devices for new technology generations. Active region widths, implantation doses, and metal line spacing are adjusted to match scaled dimensions while maintaining protective effectiveness. These parameter updates allow ESD devices to be manufactured with existing process tools and maintain manufacturing consistency, while the modified parameters ensure continued ESD protection effectiveness in new technology nodes.
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
This solution enhances the reliability and performance of ESD protection in semiconductor devices by preventing failures caused by backside dielectric breakdown and density loading effects, ensuring effective ESD current diversion and maintaining device performance across technology generations.
Implementation Method 1
electrostatic discharge (ESD) prevention devices
Data Source
AI summary
The present disclosure provides embodiments of semiconductor structures. A semiconductor structure according to the present disclosure includes a substrate, a fin-shaped structure disposed over the substrate, the fin-shaped structure including a plurality of first semiconductor layers interleaved by a plurality of second semiconductor layers, a gate structure disposed over a channel region of the fin-shaped structure, a first source/drain feature extending through at least a first portion the fin-shaped structure, a second source/drain feature extending through at least a second portion of the fin-shaped structure, and a backside metal line disposed below the substrate and spaced apart from the first source/drain feature and the second source/drain feature.