FinFET Channel Doping via Dummy Gate Self-Aligned Recess
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Solution Overview
Problem
As semiconductor devices continue to shrink in feature size, challenges arise in controlling the shape of the channel region of FinFET devices, affecting their performance, particularly in achieving uniform doping profiles and recess shapes which impact turn-on characteristics and resistance.
Innovation Solution
The method involves a plasma doping process to create a uniform doping profile in the channel region, followed by selective etching to form recesses that are self-aligned to the doped regions, allowing for epitaxial growth of source/drain regions, and subsequent replacement gate formation to enhance FinFET performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional doping processes are used to dope the channel region, then doping can be achieved, but uniform doping profile cannot be obtained which affects turn-on characteristics and resistance
Solution Approach 1:
A dummy gate structure is formed over the fin structure before the doping process. This dummy gate serves as a mask to define the channel region, ensuring that dopants are introduced only into the desired areas. The preliminary formation of this gating structure enables precise control over doping locations and profiles, directly resolving the contradiction by achieving uniform doping while maintaining reliable turn-on characteristics.
2Productivity
If feature size is reduced to increase integration density, then more components can be integrated, but control over channel region shape deteriorates
Solution Approach 1:
The gate structure is segmented into a dummy gate portion and a real gate portion. The dummy gate is formed first to enable precise doping and channel definition, then removed and replaced with the actual gate. This segmentation allows the channel region shape to be precisely controlled during fabrication while maintaining the benefits of reduced feature sizes for high integration density.
Solution Approach 2:
The dummy gate structure is formed in advance before the doping process to define and control the channel region shape. This preliminary structuring enables precise geometric control of the channel even as feature sizes are reduced, allowing integration density to increase without sacrificing manufacturing precision.
3Reliability
If recesses are formed in the fin structure to create source/drain regions, then device performance can be enhanced, but alignment precision becomes difficult to maintain
Solution Approach 1:
The dummy gate structure is formed beforehand to serve as a self-aligned mask during the recess formation process. This ensures that recesses are automatically positioned with high precision relative to the gate, eliminating alignment errors. The preliminary dummy gate structure thus enables both enhanced device performance through proper recess formation and maintained manufacturing precision through self-alignment.
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 results in improved uniformity of the channel region profile, leading to better turn-on characteristics, reduced resistance, and enhanced device speed and efficiency.
Implementation Method 1
a plasma doping process is performed on the fin structure to form a doped region in the channel
Implementation Method 2
implanting a dopant in the fin structure to form a doped region in the channel
Implementation Method 3
a first etching process is performed on the doped region to form a recess with self-aligned edges
Implementation Method 4
source/drain regions are epitaxially grown in the recess
Data Source
AI summary
A method includes forming a fin over a substrate, forming a dummy gate structure over the fin, forming a first spacer over the dummy gate structure, implanting a first dopant in the fin to form a doped region of the fin adjacent the first spacer, removing the doped region of the fin to form a first recess, wherein the first recess is self-aligned to the doped region, and epitaxially growing a source/drain region in the first recess.