SiGe Source/Drain Structure Without Inner Spacers for Channel Stress
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Solution Overview
Problem
The presence of inner spacers between the gate structure and source/drain patterns in semiconductor devices, particularly in nanosheet transistors, can affect device performance due to crystal defects and reduced stress on channel layers, impacting mobility and overall device efficiency.
Innovation Solution
The formation of source/drain patterns with varying germanium concentrations without inner spacers, utilizing epitaxial growth to create regions with different germanium concentrations, including a contact layer with specific germanium concentrations to enhance stress on channel layers, thereby improving mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inner spacers are formed between gate structure and source/drain patterns, then isolation and protection are improved, but crystal defects increase and stress on channel layers is reduced
Solution Approach 1:
The patent removes inner spacers from the device structure, extracting the harmful element that causes crystal defects and reduces stress on channel layers. This eliminates the source of the problem while maintaining device functionality through alternative isolation methods.
Solution Approach 2:
The patent applies different germanium concentrations at different locations within the source/drain patterns. High Ge concentration regions are positioned where stress is needed on the channel layers, while lower Ge concentration regions are used where crystal growth stability is prioritized. This local variation in material composition optimizes both stress and defect prevention.
2Ease of operation
If source/drain patterns are formed without inner spacers, then stress on channel layers and mobility are improved, but manufacturing complexity increases due to precise Ge concentration control
Solution Approach 1:
The patent changes the germanium concentration parameter within the source/drain patterns to achieve different functional regions. By controlling Ge concentration gradients during epitaxial growth, the patent optimizes stress distribution and mobility without requiring inner spacers, thus improving device performance while managing manufacturing complexity through material composition control.
Solution Approach 2:
The patent uses composite source/drain structures with varying germanium concentrations embedded in silicon. This composite approach allows different regions of the source/drain pattern to have optimized properties for their specific functions: high Ge for stress enhancement and low Ge for crystal growth stability, achieving improved mobility without inner spacers.
3Ease of operation
If varying germanium concentrations are used in source/drain patterns, then stress and mobility are enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The patent systematically varies the germanium concentration parameter during the epitaxial growth process to create optimized source/drain regions. By controlling Ge concentration gradients, the patent achieves enhanced stress and mobility while managing manufacturing precision through established semiconductor fabrication techniques.
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 eliminates crystal defects and enhances mobility by allowing sufficient stress to be exerted on channel layers, improving the performance of semiconductor devices.
Implementation Method 1
allowing sufficient stress to be exerted on channel layers, thereby improving mobility
Implementation Method 2
utilizing epitaxial growth to create regions with different germanium concentrations
Data Source
AI summary
Provided is a semiconductor device which includes: a channel structure; a source/drain pattern on the channel structure; a gate structure on the channel structure; and a contact layer on the channel structure, wherein the contact layer contacts the source/drain pattern and includes silicon germanium (SiGe), the source/drain pattern includes a 1st portion and a 2nd portion between the 1st portion and the contact layer, the 1st portion and the 2nd portion have different germanium (Ge) concentrations, and a Ge concentration in the contact layer is higher than a Ge concentration of the 1st portion and lower than a Ge concentration of the 1st portion.