Stress-Generating Epitaxial Regions for Semiconductor Channel Uniformity
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Solution Overview
Problem
In the manufacture of highly integrated semiconductor devices, non-uniform crystal growth in source and drain regions during selective epitaxial growth (SEG) can lead to defects such as stacking faults, negatively affecting the reliability and performance of the devices due to non-uniform stress distribution in channel regions.
Innovation Solution
The formation of stress-generating epitaxial regions, such as SiGe or SiC, on either side of the channel region to uniformly apply compressive or tensile stress, optimizing the contact surface area with the channel region and mitigating stacking faults by ensuring uniform crystal growth in the same direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If selective epitaxial growth (SEG) process is used to form source and drain regions, then carrier mobility is enhanced through stress application, but non-uniform crystal growth causes stacking fault defects
Solution Approach 1:
The patent changes the material composition parameter by forming SiGe epitaxial regions with controlled germanium content (e.g., 10-50% Ge) adjacent to the channel region. This material parameter change enables stress application to enhance carrier mobility while the controlled epitaxial growth process maintains crystal uniformity, preventing stacking faults.
Solution Approach 2:
The patent applies local quality by creating SiGe epitaxial regions specifically in the source and drain areas adjacent to the channel, while keeping the channel region itself as pure silicon or different composition. This localized material differentiation provides stress where needed without compromising the crystal quality of the channel region.
2Reliability
If stress layers are formed to enhance carrier mobility, then device performance is improved, but stress distribution becomes non-uniform causing defects
Solution Approach 1:
The patent controls the thickness parameter of the SiGe epitaxial regions (e.g., 5-50 nm) and germanium composition to optimize stress application. By precisely controlling these parameters, uniform stress is distributed across the channel region, enhancing carrier mobility while maintaining compositional stability and preventing defect formation.
Solution Approach 2:
The patent applies stress through SiGe regions that extend partially into the source and drain areas but are confined to specific thickness ranges. This partial action provides sufficient stress enhancement for improved device performance while avoiding excessive stress concentration that would cause non-uniformity and defects.
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 carrier mobility and device performance by uniformly applying stress to the channel region, reducing defects and improving reliability through optimized stress distribution and crystal growth alignment.
Implementation Method 1
it has been determined that enhanced carrier mobility is achievable by applying a tensile or compressive stress to a channel region by forming a stress layer in a semiconductor device
Implementation Method 2
each of a source region and a drain region may be formed as a tensile stress layer or a compressive stress layer by, for example, a selective epitaxial growth (SEG) process
Data Source
AI summary
A semiconductor device comprises a substrate and first and second stress-generating epitaxial regions on the substrate and spaced apart from each other. A channel region is on the substrate and positioned between the first and second stress-generating epitaxial regions. A gate electrode is on the channel region. The channel region is an epitaxial layer, and the first and second stress-generating epitaxial regions impart a stress on the channel region.