Gate Tie-Off Structure With Dummy Gate For Electrical Isolation
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Solution Overview
Problem
Existing gate tie-off structures face challenges in providing electrical isolation between transistors without cutting fins, leading to process variation-sensitive stresses and misalignment issues that affect transistor functionality.
Innovation Solution
A gate tie-off structure that uses a metal interconnect to electrically couple dummy gates to a source, allowing for continuous fin structures and supporting various abutment scenarios without requiring adjacent sources, thereby overcoming the limitations of traditional approaches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional gate tie-off structures are used to provide electrical isolation between transistors, then isolation is achieved, but process variation-sensitive stresses and misalignment issues occur that affect transistor functionality
Solution Approach 1:
The patent introduces a dummy gate structure as an intermediary element that mediates between adjacent transistor gates. This dummy gate is positioned between the gates of adjacent transistors and is electrically isolated from both, providing a buffer that prevents direct electrical interaction while maintaining proper isolation. The dummy gate acts as a mediator that resolves the alignment precision issues by providing a dedicated isolation structure that does not require precise alignment with the adjacent transistor gates.
2Reliability
If dummy gates are used for gate tie-off, then electrical isolation is provided, but misalignment issues arise that affect transistor functionality
Solution Approach 1:
The patent merges the dummy gate structure with the existing gate structure formation processes. The dummy gate is formed using the same polysilicon deposition and patterning steps as the functional gates, combining multiple functions into a unified structure. This merging approach reduces device complexity by eliminating separate processing steps while maintaining the electrical isolation function.
3Ease of manufacture
If continuous fin structures are used, then manufacturing is simplified, but process variation-induced stress increases
Solution Approach 1:
The patent segments the continuous fin structure by introducing dummy gates that create electrical isolation regions. While the physical fin structure remains continuous for manufacturing simplicity, the electrical isolation provided by the dummy gates effectively segments the electrical pathways, reducing the propagation of process variation-induced stress across adjacent transistors. This allows the benefits of continuous fins to be maintained while mitigating the stress issue through electrical segmentation.
Data Source
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AI summary
According to certain aspects of the present disclosure, a chip includes a first gate, a second gate, a first source, a first source contact disposed on the first source, a metal interconnect above the first source contact and the first gate, a first gate contact electrically coupling the first gate to the metal interconnect, and a first via electrically coupling the first source contact to the metal interconnect. The chip also includes a power rail, and a second via electrically coupling the first source contact to the power rail. The second gate is between the first source and the first gate, and the metal interconnect passes over the second gate.