Rounded Source/Drain Epitaxial Layers for Nanostructure Junction Leakage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As semiconductor devices continue to shrink in size, junction leakage from source/drain regions into nanostructures becomes a significant issue, affecting device performance and reliability.
Innovation Solution
The formation of first epitaxial layers with round convex profiles over the sidewalls of nanostructures, achieved through controlled epitaxial growth using a low flow rate of an etchant-containing precursor, increases the thickness at the corners of the nanostructures, reducing junction leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If minimum feature size is reduced to improve integration density, then more components can be integrated into a given area, but junction leakage from source/drain regions into nanostructures increases
Solution Approach 1:
The patent applies local quality by forming a liner layer specifically at the corners of nanostructures where junction leakage occurs. This liner layer has different properties (higher dopant concentration or different material composition) than the bulk source/drain regions, providing localized protection against dopant diffusion into the channel region while maintaining overall device functionality and integration density.
Solution Approach 2:
The liner layer acts as an intermediary between the source/drain regions and the nanostructure channels. It serves as a buffer zone that intercepts and blocks dopant diffusion before it reaches the channel region, thereby reducing junction leakage without requiring changes to the overall device architecture or integration scheme.
2Productivity
If epitaxial growth is performed with high etchant precursor flow rate to increase growth speed, then productivity improves, but junction leakage increases due to reduced liner layer thickness at corners
Solution Approach 1:
The patent applies preliminary action by forming the liner layer with rounded corners at an early stage of epitaxial growth, before subsequent high-speed growth occurs. This preliminary rounding action ensures that the liner layer maintains adequate thickness at corners even when faster growth rates are used later, preventing junction leakage while preserving productivity.
Solution Approach 2:
The patent utilizes spheroidality by intentionally rounding the corners of the liner layer during epitaxial growth. This curvature prevents the formation of sharp corners where dopant diffusion is most problematic, ensuring uniform dopant distribution and reduced junction leakage even when high growth speeds are employed to maintain productivity.
3Reliability
If liner layer thickness is increased at nanostructure corners to reduce junction leakage, then reliability improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies self-service by utilizing the self-aligned nature of in-situ doped epitaxial growth. The liner layer is formed automatically in position and with appropriate thickness through the epitaxial process itself, without requiring separate deposition or patterning steps. This self-service approach reduces manufacturing precision requirements while ensuring adequate liner layer thickness at corners for improved reliability.
Solution Approach 2:
The patent utilizes parameter changes by adjusting epitaxial growth conditions (temperature, pressure, precursor flow rates, doping conditions) to control the liner layer formation. By optimizing these parameters, the process automatically achieves the desired liner layer thickness and corner rounding, reducing reliability issues without imposing stringent manufacturing precision requirements.
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 effectively decreases junction leakage, enhancing the performance and reliability of semiconductor devices by minimizing dopant diffusion.
Implementation Method 1
forming a first epitaxial layer over the substrate, the gate structure, and the semiconductor fin, wherein the first epitaxial layer comprises a first doping concentration
Implementation Method 2
the first epitaxial layer comprises a first doping concentration, the second epitaxial layer comprises a second doping concentration, and the third epitaxial layer comprises a third doping concentration
Data Source
AI summary
A device includes a first nanostructure over a substrate and a first source/drain region adjacent the first nanostructure. The first source/drain region includes a first epitaxial layer covering a first sidewall of the first nanostructure. The first epitaxial layer has a first concentration of a first dopant. The first epitaxial layer has a round convex profile opposite the first sidewall of the first nanostructure in a cross-sectional view. The first source/drain region further includes a second epitaxial layer covering the round convex profile of the first epitaxial layer in the cross-sectional view. The second epitaxial layer has a second concentration of the first dopant, the second concentration being different from the first concentration.