FinFET LDD Dopant Uniformity via Intermediary Layer
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Solution Overview
Problem
Existing FinFET devices face challenges in achieving uniform dopant distribution along the top surface and sidewalls of the fin in the lightly-doped drain (LDD) region, leading to non-uniform dopant concentration and potential performance issues due to implant shadowing effects and lateral encroachment of dopants into the channel region.
Innovation Solution
A FinFET structure and method that involves forming a first dopant layer over the top surface and sidewalls of the fin, with a capping layer and diffusion barrier to ensure uniform dopant distribution, using atomic layer deposition (ALD) and annealing to diffuse dopants, and a second dopant layer for opposite-type fins, to maintain identical dopant concentrations across the top and sidewall regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional implantation methods are used to dope the LDD region, then dopant delivery is achieved, but non-uniform dopant distribution occurs due to implant shadowing effects and lateral encroachment
Solution Approach 1:
A dopant layer is formed over the fin structure before gate formation, establishing the dopant distribution pattern in advance. This preliminary doping action allows subsequent processing steps to proceed without disrupting the established uniform dopant concentration in the LDD region.
Solution Approach 2:
The patent introduces a dopant layer as an intermediary material between the implantation source and the fin structure. This dopant layer acts as a controlled delivery mechanism, replacing direct implantation and enabling precise control over dopant distribution uniformity while preventing lateral encroachment.
2Power
If dopant concentration is increased to improve current flow, then transistor performance improves, but non-uniform distribution causes performance variations across the device
Solution Approach 1:
The dopant layer is selectively positioned and configured to provide locally optimized dopant concentration in the LDD region. By controlling the dopant layer characteristics in specific locations, the patent achieves high dopant concentration where needed for current flow while maintaining uniformity across the top surface and sidewalls.
Solution Approach 2:
The patent controls dopant concentration by adjusting parameters of the dopant layer formation process, including layer thickness, composition, and deposition conditions. These parameter changes enable precise control over dopant concentration uniformity while achieving the required levels for optimal current flow and transistor performance.
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
The solution achieves a uniform dopant distribution with a dopant concentration difference of less than 5% between the top and sidewall regions, improving device performance by ensuring consistent dopant levels across the LDD region, thereby enhancing current flow and transistor performance.
Implementation Method 1
a first dopant layer covering a top surface and sidewalls of a junction portion of a first fin and configured to provide dopants of a first conductive type to the junction portion of the first fin
Implementation Method 2
using atomic layer deposition (ALD) and annealing to diffuse dopants
Data Source
AI summary
Present disclosure provides a FinFET structure, including a plurality of fins, a gate, and a first dopant layer. The gate is disposed substantially orthogonal over the plurality of fins, covering a portion of a top surface and a portion of sidewalls of the plurality of fins. The first dopant layer covers the top surface and the sidewalls of a junction portion of a first fin, configured to provide dopants of a first conductive type to the junction portion of the first fin. The junction portion is adjacent to the gate.