Auxiliary Spacers in Semiconductor Source/Drain Regions
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Solution Overview
Problem
As semiconductor devices are scaled down, the integration of MOSFETs leads to degraded characteristics, necessitating improved manufacturing methods to enhance performance and reliability.
Innovation Solution
The semiconductor device design includes distinct regions with specific active patterns, gate structures, and source/drain regions, featuring auxiliary spacers and epitaxial layers to optimize geometry and material distribution, with varying widths and slopes to improve epitaxial growth and device reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If MOSFETs are scaled down to increase integration, then device density increases, but device characteristics are degraded
Solution Approach 1:
The source/drain region is divided into multiple segments along the channel length, including lightly-doped extension regions, heavily-doped main regions, and intermediate regions. This segmentation allows each region to be independently optimized for different functions: extensions provide gradual doping transitions to reduce short-channel effects, while main regions provide strong carrier injection, thereby maintaining device characteristics at scaled dimensions
Solution Approach 2:
Different doping concentrations and profiles are applied to different spatial locations within the source/drain structure. The extension regions near the channel have lower doping concentrations to reduce field effects, while regions farther from the channel have higher doping concentrations for efficient carrier supply. This local quality variation enables the device to maintain performance despite overall scaling
2Reliability
If source/drain regions are heavily doped to improve carrier injection, then conductivity increases, but dopant diffusion causes junction migration and short-channel effects
Solution Approach 1:
Lightly-doped extension regions are formed in the source/drain areas before the main channel formation and before heavy doping of the main source/drain regions. These pre-formed extensions create a doping profile that gradually transitions from the substrate, which prevents excessive field effects and reduces dopant diffusion into the channel during subsequent processing steps, thereby maintaining junction position precision
Solution Approach 2:
The source/drain structure employs a composite doping profile combining lightly-doped and heavily-doped regions in a single continuous structure. This composite approach allows the lightly-doped extensions to act as diffusion barriers while the heavily-doped main regions provide high carrier concentration, resolving the contradiction between conductivity and junction control
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 design enhances the reliability and performance of semiconductor devices by optimizing the geometry and material distribution, particularly through improved epitaxial growth, preventing connection between source/drain regions and ensuring uniformity, thus addressing the challenges of scaling down MOSFETs.
Implementation Method 1
improved epitaxial growth
Data Source
AI summary
Provided is a semiconductor device which includes a substrate including a first region and a second region different from the first region, a first active pattern provided on the substrate in the first region, a second active pattern provided on the substrate in the second region, a first gate structure crossing over the first active pattern and a second gate structure crossing over the second active pattern, first source/drain regions disposed on the first active pattern at opposite sides of the first gate structure, second source/drain regions disposed on the second active pattern at opposite sides of the second gate structure, and auxiliary spacers disposed in the first region to cover a lower portion of each of the first source/drain regions.