FinFET Source Drain Segmentation for Carrier Mobility
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Solution Overview
Problem
Current double-gate FinFET manufacturing processes face challenges in achieving precise control over fin structures and source drain formation, leading to suboptimal carrier mobility and increased short-channel effects, which affect the performance and efficiency of semiconductor devices.
Innovation Solution
The process involves forming fins on a semiconductor substrate, creating shallow trench isolation structures, forming dummy gates, patterning and etching to define recesses for source drain structures, and replacing dummy gates with actual gates, while using spacers and epitaxial growth to enhance carrier mobility and reduce short-channel effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional FinFET manufacturing processes are used, then fabrication is simpler, but carrier mobility is suboptimal and short-channel effects increase
Solution Approach 1:
The source and drain regions are segmented into multiple portions (first source/drain portions and second source/drain portions) with different doping concentrations and depths. This segmentation allows optimized carrier mobility in the channel region while maintaining effective control over short-channel effects through the multi-layered source/drain structure.
Solution Approach 2:
Different regions of the source/drain structures are assigned different doping concentrations and depths to optimize local properties. The first source/drain portions have higher doping concentrations near the channel for effective short-channel control, while the second source/drain portions extend deeper with lower doping to reduce scattering and improve carrier mobility in the channel region.
2Reliability
If precise control over fin structures is not achieved, then manufacturing is easier, but short-channel effects increase and performance decreases
Solution Approach 1:
Dummy gates are formed preliminarily during the fin formation process to provide structural support and define the fin geometry precisely. These dummy gates are later replaced with actual gates, but their preliminary presence ensures precise fin structure control during manufacturing, effectively preventing short-channel effects.
Solution Approach 2:
The dummy gates serve as intermediary structures that facilitate precise fin formation. They act as a mediator between the manufacturing process and the final fin structure, ensuring geometric precision during fabrication before being replaced by the functional gates.
3Reliability
If source drain structures are not optimally formed, then manufacturing is simpler, but carrier mobility decreases
Solution Approach 1:
The source/drain structures are divided into multiple segments with different doping concentrations and depths. The first source/drain portions are formed with higher doping near the channel interface, while the second source/drain portions extend deeper with lower doping, creating an optimized gradient structure that enhances carrier mobility through reduced scattering while maintaining manufacturing feasibility.
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 enables improved carrier mobility and reduced short-channel effects, enhancing the performance and efficiency of semiconductor devices by precise control over fin and source drain structures, leading to better device performance.
Implementation Method 1
epitaxially growing a source drain structure in the recess
Data Source
AI summary
A method includes forming a fin structure over a substrate; forming an isolation structure around the fin structure; etching the fin structure to form a recess in the fin structure; epitaxially growing a source drain structure in the recess; depositing a capping layer over a first portion of the source drain structure, in which the first portion of the source drain structure is over the isolation structure; recessing the isolation structure to expose a second portion of the source drain structure; and etching the second portion of the source drain structure, in which the first portion of the source drain structure remains over the isolation structure after etching the second portion of the source drain structure.