Epitaxial Source/Drain Doping for FinFET Contact Resistance
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Solution Overview
Problem
Current methods for manufacturing FinFETs face challenges in achieving stable source/drain extension regions due to ion implantation-induced surface defects and non-uniform doping, leading to increased contact resistance and short channel effects.
Innovation Solution
The method involves forming raised source/drain regions epitaxially and then doping them through these regions, with adjustments in tilt angles for controlled junction depth and subsequent annealing to diffuse dopants, ensuring uniform doping and mitigating short channel effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ion implantation is performed to form source/drain extension regions, then doping is achieved, but surface defects and non-uniform doping occur leading to increased contact resistance
Solution Approach 1:
The patent performs ion implantation to form a punch-through stop layer in the middle of fins before forming source/drain extension regions. This preliminary doping action suppresses parasitic channel effects and creates a foundation for subsequent uniform doping. The pre-formed stop layer ensures controlled dopant distribution and prevents non-uniform doping in the source/drain extension regions, thereby reducing contact resistance while maintaining manufacturing precision.
Solution Approach 2:
The patent applies different doping strategies to different regions: ion implantation is used specifically in the middle of fins to form the punch-through stop layer, while selective epitaxial growth is used for source/drain extension regions. This localized quality approach ensures that each region receives the appropriate doping treatment, achieving uniform doping in source/drain extensions and reducing contact resistance without causing parasitic channel effects.
2Reliability
If ion implantation is performed to form source/drain extension regions, then doping is achieved, but short channel effects increase due to non-uniform doping
Solution Approach 1:
The patent performs ion implantation to form a punch-through stop layer in the middle of fins before forming source/drain extension regions. This preliminary doping action suppresses parasitic channel effects and creates a foundation for subsequent uniform doping. The pre-formed stop layer ensures controlled dopant distribution and prevents non-uniform doping in the source/drain extension regions, thereby reducing contact resistance while maintaining manufacturing precision.
Solution Approach 2:
The patent applies different doping strategies to different regions: ion implantation is used specifically in the middle of fins to form the punch-through stop layer, while selective epitaxial growth is used for source/drain extension regions. This localized quality approach ensures that each region receives the appropriate doping treatment, achieving uniform doping in source/drain extensions and reducing contact resistance without causing parasitic channel effects.
3Reliability
If conventional doping methods are used, then source/drain extension regions are formed, but structural stability decreases due to surface defects
Solution Approach 1:
The patent performs ion implantation to form a punch-through stop layer in the middle of fins before forming source/drain extension regions. This preliminary doping action suppresses parasitic channel effects and creates a foundation for subsequent uniform doping. The pre-formed stop layer ensures controlled dopant distribution and prevents non-uniform doping in the source/drain extension regions, thereby reducing contact resistance while maintaining manufacturing precision.
Solution Approach 2:
The patent applies different doping strategies to different regions: ion implantation is used specifically in the middle of fins to form the punch-through stop layer, while selective epitaxial growth is used for source/drain extension regions. This localized quality approach ensures that each region receives the appropriate doping treatment, achieving uniform doping in source/drain extensions and reducing contact resistance without causing parasitic channel effects.
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 improves the stability of the LDD/SDE structure and reduces short channel effects by achieving uniform doping and reducing defects, thereby enhancing the performance and reliability of the FinFET device.
Implementation Method 1
performing ion implantation into or depositing a doped layer and performing annealing on the fins, to form a Punch-Through Stop Layer (PTSL) in the middle of each of the fins
Implementation Method 2
selectively epitaxially growing the same or similar material, preferably SiGe, SiC or the like with higher stress than Si to improve the carrier mobility, on the fins on opposite sides of the gate spacer
Implementation Method 3
performing ion implantation into or depositing a doped layer and performing annealing on the fins
Data Source
AI summary
A method for manufacturing a semiconductor device comprises, including forming a plurality of fins on a substrate, forming, a dummy gate stack on the fins forming a gate spacer on opposite sides of the dummy gate stack, forming source/drain trenches by etching the fins with the gate spacer and the dummy gate stack as a mask, forming source/drain extension regions on the bottom and sides of the trenches by performing lightly-doping ion implantation; and by performing epitaxial growth in and/or on the source/drain trenches, removing the dummy gate stack to form a gate trench; and forming a gate stack in the gate trench.