Fin Body Epitaxial Layer Segmentation for Electron Mobility
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Solution Overview
Problem
Current semiconductor devices, such as FinFETs, face challenges in optimizing electrical characteristics due to variations in fin body lattice structures and epitaxial layer growth, which affect electron mobility and device performance.
Innovation Solution
The semiconductor device incorporates fin bodies with distinct lower and upper lattice structures, where the epitaxial layer covers the upper portion and features a surface profile with convex and concave portions, enhancing electron mobility by applying tensile stress to the upper body portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform epitaxial layer is formed on the fin body, then the manufacturing process is simple, but the electron mobility and electrical characteristics are insufficient
Solution Approach 1:
The epitaxial layer is divided into multiple regions with different thicknesses: a first thickness in the first region, a second thickness greater than the first in the second region, and a third thickness greater than the second in the third region. This local variation in thickness creates specific stress distributions that improve electron mobility in different areas of the fin body, resolving the contradiction between electrical performance and structural simplicity.
Solution Approach 2:
The epitaxial layer is segmented into distinct regions (first, second, and third regions) with different thickness characteristics. This segmentation allows independent optimization of stress conditions in each region, enabling improved electrical characteristics while maintaining a manageable manufacturing process through selective epitaxial growth.
2Reliability
If the epitaxial layer thickness is increased to improve electron mobility, then tensile stress is enhanced, but the manufacturing precision becomes more difficult to control
Solution Approach 1:
Different thicknesses are implemented in different regions to achieve optimal stress conditions without requiring uniformly high thickness throughout. The first region has a smaller thickness, the second region has an intermediate thickness, and the third region has the greatest thickness. This approach enhances electron mobility through localized stress while maintaining controllable manufacturing precision through selective growth processes.
3Reliability
If varied thickness regions are formed in the epitaxial layer, then electron mobility is improved through stress control, but the manufacturing process complexity increases
Solution Approach 1:
Mandrel structures are formed beforehand with different heights corresponding to the desired epitaxial layer thicknesses in different regions. These mandrels serve as templates that guide the selective epitaxial growth process, enabling the formation of varied thickness regions without requiring complex real-time control during the epitaxial growth itself. This preliminary structuring simplifies the overall manufacturing process while achieving the desired stress distribution.
Solution Approach 2:
Mandrel structures act as intermediary elements that translate design requirements for varied epitaxial thickness into actual physical structures. The mandrels are formed through standard lithography and deposition processes, then used as templates for selective epitaxial growth. This intermediary approach enables complex thickness variations to be achieved through relatively simple manufacturing steps.
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 configuration improves the electrical characteristics of the fin body by increasing electron mobility and reliability, leading to enhanced performance in semiconductor devices.
Implementation Method 1
The epitaxial layer may be formed on a surface of the fin body by a selective epitaxial growth (SEG) process
Implementation Method 2
enhancing electron mobility by applying tensile stress to the upper body portion
Data Source
AI summary
A semiconductor device can include a substrate and a fin body that protrudes from a surface of the substrate. The fin body can include a lower portion having a first lattice structure and an upper portion, separated from the lower portion by a boundary, the upper portion having a second lattice structure that is different than the first lattice structure. An epitaxially grown epitxial layer can be on the lower and upper portions.