Shaped Epitaxial Source/Drain Regions for Small-Pitch Fin Isolation
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Solution Overview
Problem
As semiconductor devices continue to shrink in feature size, challenges arise in integrating more components into a given area, including issues with fin formation, isolation, and epitaxial growth, which affect the efficiency and reliability of transistors and other components.
Innovation Solution
The process involves forming fins on a substrate, creating isolation regions, and using epitaxial growth to form source/drain regions with a specific structure, including a bulk, shaping, and finishing section, utilizing precursor materials and etching precursors to control the shape and doping of these regions, enhancing the etching efficiency and separation of source/drain regions.
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 additional problems arise in fin formation, isolation, and epitaxial growth that affect transistor efficiency and reliability
Solution Approach 1:
The source/drain region is divided into multiple distinct sections: a bulk section formed by epitaxial growth, a shaping section with modified crystalline structure, and a finishing section. This segmentation allows each section to perform its specific function optimally, resolving the contradiction by enabling precise control over the epitaxial growth process at reduced feature sizes while maintaining reliability
Solution Approach 2:
The shaping section is created with a modified crystalline structure through introduction of a shaping dopant, giving it different local properties compared to the bulk and finishing sections. This local quality change enables selective etching and precise shape control during fabrication, allowing reliable transistor formation at smaller feature sizes without compromising overall device performance
2Manufacturing precision
If epitaxial growth is used to form source/drain regions, then doping control and shape precision can be improved, but process complexity increases due to multiple precursors and etching steps
Solution Approach 1:
The shaping dopant is introduced simultaneously with the epitaxial growth process using a single precursor that provides both the shaping element and the dopant. This merging of functions reduces process complexity compared to separate doping and shaping steps, while still achieving precise doping control and shape definition through the integrated approach
3Productivity
If fin size is reduced to increase integration density, then more fins can be packed into a given area, but fin formation and isolation become more difficult affecting device reliability
Solution Approach 1:
The shaping section with modified crystalline structure is formed during the epitaxial growth process itself, before subsequent fabrication steps. This preliminary action of creating the shaped region with enhanced etch selectivity makes later fin formation and isolation steps easier, resolving the contradiction by preparing the structure in advance to facilitate subsequent manufacturing at reduced feature sizes
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 allows for improved integration density, enhanced etching selectivity, and better control over the shape and doping of source/drain regions, addressing issues of component integration and reliability in smaller pitch sizes.
Implementation Method 1
epitaxially growing a bulk source/drain region onto a substrate
Implementation Method 2
cleaning the bulk source/drain region, wherein the cleaning the bulk source/drain region modifies a crystalline structure of a surface of the bulk source/drain region
Data Source
AI summary
A source/drain region of a semiconductor device is formed using an epitaxial growth process. In an embodiment a first step comprises forming a bulk region of the source/drain region using a first precursor, a second precursor, and an etching precursor. A second step comprises cleaning the bulk region with the etchant along with introducing a shaping dopant to the bulk region in order to modify the crystalline structure of the exposed surfaces. A third step comprises forming a finishing region of the source/drain region using the first precursor, the second precursor, and the etching precursor.