Source/Drain Epitaxy Boosting Layers for Dopant Activation
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Solution Overview
Problem
Existing methods for forming stressor regions in semiconductor devices, such as MOSFETs, are inadequate in ensuring proper dopant bonding with the source/drain material, leading to point defects and reduced dopant activation due to dopant clustering, which affects carrier mobility and device performance.
Innovation Solution
A layered growth approach is introduced, where an undoped boosting layer is formed within the source/drain regions to provide additional bonding sites for dopants, increasing the availability of vacancies and enhancing dopant bonding, thereby reducing clustering and activating more dopants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dopant concentration is increased in source/drain regions, then carrier mobility is improved, but dopant clustering occurs leading to reduced dopant activation
Solution Approach 1:
The source/drain region is segmented into multiple alternating layers of doped epitaxy and undoped boosting layers. This segmentation prevents dopant clustering by distributing dopants across multiple discrete doped layers separated by undoped regions, allowing each layer to be properly activated while maintaining high overall dopant concentration for improved carrier mobility.
Solution Approach 2:
Undoped boosting layers are introduced as intermediary regions between doped epitaxy layers. These boosting layers serve as mediators that provide additional bonding sites for dopants without introducing dopant clustering, thereby enhancing dopant activation while maintaining the benefits of high dopant concentration.
2Reliability
If existing methods are used to form stressor regions, then device performance is partially improved, but point defects are generated due to improper dopant bonding
Solution Approach 1:
The stressor region formation is segmented into multiple alternating doped and undoped layers. This segmentation allows proper dopant bonding in each doped layer by providing sufficient bonding sites within the undoped boosting layers, thereby improving device performance while eliminating point defects caused by improper dopant bonding.
Solution Approach 2:
The dopant concentration profile is changed from a uniform distribution to a layered distribution with alternating high and low concentration regions. This parameter change allows optimization of dopant bonding conditions in each layer, improving device performance while preventing point defects through controlled dopant distribution.
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 method boosts dopant concentration in source/drain areas, reducing extended defects and improving the performance of semiconductor devices by ensuring better dopant activation and increased carrier mobility.
Implementation Method 1
A layered growth approach is introduced, where an undoped boosting layer is formed within the source/drain regions
Data Source
AI summary
A dopant boost in the source/drain regions of a semiconductor device, such as a transistor can be provided. A semiconductor device can include a doped epitaxy of a first material having a plurality of boosting layers embedded within. The boosting layers can be of a second material different from the first material. Another device can include a source/drain feature of a transistor. The source/drain feature includes a doped source/drain material and one or more embedded distinct boosting layers. A method includes growing a boosting layer in a recess of a substrate, where the boosting layer is substantially free of dopant. The method also includes growing a layer of doped epitaxy in the recess on the boosting layer.