Uniform Grid Metal Gate With Trench Contact Cut for Dense Nanowire ICs
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Solution Overview
Problem
The scaling of multi-gate and nanowire transistors in integrated circuits poses challenges in maintaining mobility and short channel control, particularly due to constraints on lithographic processes, leading to trade-offs between feature dimension and spacing, and complex processing schemes are costly and introduce variation.
Innovation Solution
The implementation of a uniform grid metal gate and trench contact cut structure, using a 'plug-last' approach for gate dielectric and work function metal deposition, and employing angled plasma etching for self-aligned plug removal, simplifies the process and reduces cost and variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional multi-gate transistor fabrication processes are used, then device density increases through scaling, but process complexity and cost increase significantly
Solution Approach 1:
The fabrication process is divided into distinct stages: forming gate dielectric plugs in isolation trenches, depositing work function metal, and selectively removing plugs. This segmentation allows each step to be optimized independently, reducing overall process complexity while maintaining high device density
Solution Approach 2:
Gate dielectric plugs are formed in isolation trenches before metal gate deposition. This preliminary action establishes the final gate structure geometry early in the process, enabling subsequent metal deposition to proceed without additional patterning steps, thereby reducing complexity
2Productivity
If feature dimensions are reduced to increase device density, then capacity increases, but lithographic process constraints worsen
Solution Approach 1:
The isolation trenches extend vertically through the substrate, utilizing the depth dimension to achieve electrical isolation. This allows lateral feature sizes to be reduced for higher density without compromising isolation effectiveness, as the vertical trench depth provides the isolation mechanism
3Productivity
If tight endcap spacing is maintained for high density, then device capacity increases, but process variation and defects increase
Solution Approach 1:
The work function metal deposition process is self-aligned to the gate dielectric plug edges, automatically establishing the correct endcap spacing. This self-service mechanism eliminates the need for additional lithographic alignment steps, reducing process variation and defects while maintaining tight spacing for high capacity
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 approach enhances device performance by reducing process complexity, improving robustness, and allowing for seamless work function metal deposition, while maintaining tight endcap spacing and reducing defects.
Implementation Method 1
employing angled plasma etching for self-aligned plug removal
Data Source
AI summary
Integrated circuit structures having uniform grid metal gate and trench contact cut, and methods of fabricating integrated circuit structures having uniform grid metal gate and trench contact cut, are described. For example, an integrated circuit structure includes a vertical stack of horizontal nanowires. A gate electrode is over the vertical stack of horizontal nanowires. A conductive trench contact is adjacent to the gate electrode. A dielectric sidewall spacer is between the gate electrode and the conductive trench contact. A first dielectric cut plug structure extends through the gate electrode, through the dielectric sidewall spacer, and through the conductive trench contact. A second dielectric cut plug structure extends through the gate electrode, through the dielectric sidewall spacer, and through the conductive trench contact, the second dielectric cut plug structure laterally spaced apart from and parallel with the first dielectric cut plug structure.