SiGe Blocking Layer for FinFET Source/Drain Etching
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Solution Overview
Problem
During the fabrication of FinFET devices, the etching of source/drain regions can be incomplete due to the presence of void spaces, leading to reliability issues and defects in the semiconductor device.
Innovation Solution
The semiconductor device incorporates a blocking layer made of a different material than the source/drain regions, specifically SiGe, which is formed below the bottom facets of the source/drain patterns to prevent etchant penetration and ensure complete etching, while also merging the source/drain patterns to enhance stress characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If etchant is provided into void space during source/drain formation, then complete etching of source/drain regions is achieved, but etchant penetrates and causes unwanted etching of other structures
Solution Approach 1:
A mandrel structure is introduced as an intermediary element that physically blocks etchant from penetrating into unwanted regions. The mandrel is positioned to fill the void space between source/drain regions, allowing etchant to access the source/drain regions for complete etching while preventing etchant from reaching and damaging other structures. This mediator structure resolves the contradiction by enabling complete etching without the harmful side effect of etchant penetration.
Solution Approach 2:
The mandrel structure is formed in advance before the etching process to preemptively prevent etchant penetration. By placing the blocking structure beforehand, the patent anticipates and counteracts the potential harmful effect of etchant penetration, allowing the etching process to proceed completely without risk of damage to surrounding structures.
2Reliability
If source/drain patterns are separated to prevent etchant penetration, then reliability is improved, but stress characteristics deteriorate
Solution Approach 1:
The solution segments the protective function from the source/drain patterns by introducing a separate mandrel structure. Instead of relying on separation of source/drain patterns to prevent etchant penetration, the mandrel is segmented and positioned specifically to block etchant paths while allowing source/drain patterns to remain connected for stress characteristics.
Solution Approach 2:
The mandrel acts as an intermediary blocking structure that prevents etchant penetration without requiring separation of source/drain patterns. This mediator enables both complete etching and maintained stress characteristics by providing a dedicated blocking element rather than relying on pattern separation.
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 effectively prevents etchant-induced etching issues, ensuring complete formation of source/drain regions and improving the reliability and stress characteristics of the semiconductor device.
Implementation Method 1
a blocking layer made of a different material than the source/drain regions, specifically SiGe, which is formed below the bottom facets of the source/drain patterns to prevent etchant penetration
Implementation Method 2
The semiconductor device incorporates a blocking layer made of a different material than the source/drain regions, specifically SiGe, which is formed below the bottom facets of the source/drain patterns to prevent etchant penetration and ensure complete etching, while also merging the source/drain patterns to enhance stress characteristics
Data Source
AI summary
A semiconductor device may have a structure that prevents or reduces an etching amount of certain portions, such as a part of a source/drain region. Adjacent active fins may be merged with a blocking layer extending between adjacent the source/drain region. The blocking layer may be of a material that is relatively high-resistant to the etchant.