Reduced-Cap SAGE Isolation for Denser FinFET Gate Spacing
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Solution Overview
Problem
The scaling of multi-gate transistors in semiconductor devices faces challenges due to constraints on lithographic processes, leading to a trade-off between feature dimension and spacing, which affects transistor layout density and performance.
Innovation Solution
The implementation of self-aligned gate endcap (SAGE) architectures with reduced or removed caps, utilizing a high-k dielectric material etch process for cap reduction, allows for self-aligned gate endcap and trench contact overlap without requiring extra space for mask registration, thereby enabling more aggressive diffusion spacing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithographic processes are used to pattern transistor features, then manufacturing simplicity is maintained, but the spacing between features must be increased to accommodate mask registration tolerances, reducing layout density
Solution Approach 1:
The gate endcap isolation structure is formed preliminarily before the gate electrode deposition, establishing self-aligned reference features that eliminate the need for subsequent mask registration. The isolation structure protrudes from the fin surface at a predetermined distance, creating a built-in alignment reference that guides subsequent processing steps without requiring additional lithographic alignment tolerances.
Solution Approach 2:
The gate endcap isolation structure serves multiple functions simultaneously: it provides electrical isolation between adjacent transistors, establishes self-alignment references for gate patterning, and defines the gate endcap overlap dimensions. This multi-functional structure eliminates the need for separate alignment markers and reduces the overall spacing requirements between transistors.
2Reliability
If gate endcap overlap is increased to improve transistor performance, then device performance is enhanced, but the spacing between adjacent transistors must be increased, reducing layout density
Solution Approach 1:
The gate endcap isolation structure provides localized electrical isolation precisely where needed at the gate ends, allowing the gate overlap to extend further without causing parasitic conduction between adjacent transistors. This localized isolation enables increased gate endcap overlap for improved transistor performance while maintaining tight spacing between adjacent device structures.
3Reliability
If cap structure is retained in SAGE architecture, then electrical isolation is maintained, but capacitance is increased and device variability is reduced
Solution Approach 1:
The dielectric material properties are optimized by selecting materials with appropriate permittivity characteristics for the gate endcap isolation structure. By carefully controlling the dielectric constant and thickness of the isolation structure, the patent achieves minimal capacitance while maintaining sufficient electrical isolation to prevent device-to-device variability and ensure reliable transistor operation.
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 transistor layout density, reduces device-to-device variability in electrical parameters, and minimizes capacitance while maintaining cell height scaling, thereby optimizing power, performance, and area (PPA) in semiconductor devices.
Implementation Method 1
utilizing a high-k dielectric material etch process for cap reduction
Data Source
AI summary
Self-aligned gate endcap (SAGE) architectures with reduced or removed caps, and methods of fabricating self-aligned gate endcap (SAGE) architectures with reduced or removed caps, are described. In an example, an integrated circuit structure includes a first gate electrode over a first semiconductor fin. A second gate electrode is over a second semiconductor fin. A gate endcap isolation structure is between the first gate electrode and the second gate electrode, the gate endcap isolation structure having a higher-k dielectric cap layer on a lower-k dielectric wall. A local interconnect is on the first gate electrode, on the higher-k dielectric cap layer, and on the second gate electrode, the local interconnect having a bottommost surface above an uppermost surface of the higher-k dielectric cap layer.