Fin Isolation Trench Structure for Source/Drain Etch Protection
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Solution Overview
Problem
The challenge in semiconductor manufacturing lies in scaling down integrated circuits while preventing damage to source/drain features and maintaining device performance, particularly in multi-gate devices like FinFETs and gate-all-around transistors, due to issues with high selective etch processes that can cause leakage current and structural damage.
Innovation Solution
Employing a high selective sheet-cut process and a boron-based pre-treatment process to enable self-aligned CMODE or CPODE etch profiles, which includes a plasma doping step to enhance etch resistance and protect source/drain features during the etching of isolation trenches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If high selective etch processes are used to scale gate pitch in multi-gate devices, then gate pitch scaling is achieved, but source/drain damage and leakage current increase
Solution Approach 1:
A mandrel structure is formed beforehand between adjacent fin structures before the etching process. This mandrel serves as a protective element that prevents source/drain damage during the subsequent etching operations, allowing aggressive gate pitch scaling without compromising device reliability.
Solution Approach 2:
The mandrel acts as an intermediary protective structure inserted between the etch process and the source/drain regions. It mediates the interaction between the etching chemistry and the sensitive source/drain features, preventing direct harmful contact while enabling the etch to proceed for gate pitch reduction.
2Reliability
If continuous poly on diffusion edge (CPODE) schemes are used to prevent leakage current, then leakage prevention is improved, but source/drain damage risk increases
Solution Approach 1:
The mandrel is formed in advance before the CPODE etching process, establishing a protective barrier that will be present during the entire etching sequence. This preliminary structure enables the CPODE scheme to prevent leakage while the mandrel simultaneously protects against source/drain damage.
Solution Approach 2:
The mandrel provides beforehand cushioning or protection to the source/drain regions. By being in place before the harmful etching action occurs, it cushions the source/drain features from damage while allowing the CPODE process to achieve its leakage prevention goal.
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 reduces the risk of source/drain damage and maintains device integrity by increasing etch resistance, allowing for more precise etching and improved device performance in aggressively scaled circuits.
Implementation Method 1
a plasma doping step to enhance etch resistance and protect source/drain features during the etching of isolation trenches
Data Source
AI summary
Embodiments of the present disclosure relate to a semiconductor device structure. The structure includes a substrate, an insulating material disposed on the substrate, a first fin structure extending upwardly from the substrate through the insulating material, a second fin structure extending upwardly from the substrate through the insulating material, a source/drain (S/D) feature disposed between the first and second fin structures, and an isolation trench structure extending through the first fin structure and into the substrate, wherein the isolation trench structure has a doped sidewall region disposed between and in contact with the S/D feature and the isolation trench structure.