FinFET Epitaxial Structure for Higher Density and Current Flow
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Solution Overview
Problem
Existing FinFET devices and fabrication methods face challenges in achieving optimal performance due to limitations in fin structure design and epitaxial growth, which affect device density, current flow, and operation speed.
Innovation Solution
The formation of a FinFET device structure involves a substrate with a fin structure embedded in an isolation structure, where a trench is created to grow an epitaxial structure with controlled volume and height, enhancing carrier mobility and reducing gate resistance by adjusting the trench depth and angle, and using suitable materials and processes like double-patterning lithography and epitaxial growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional FinFET fabrication methods are used, then manufacturing process is simpler, but device density and performance are limited
Solution Approach 1:
The fabrication process is divided into multiple stages including forming first and second trenches at different depths, selective epitaxial growth in specific regions, and staged doping processes. This segmentation allows precise control over device characteristics while achieving high device density through systematic process breakdown
Solution Approach 2:
The patent transitions from planar device architecture to three-dimensional FinFET structure with vertical fins extending from the substrate. This dimensional change increases the effective channel area and device density while maintaining controllability through the multi-trench fabrication approach
2Productivity
If fin structure dimensions are reduced to increase device density, then device density improves, but short channel effects increase
Solution Approach 1:
The patent employs nested trench structures where a first trench extending to a first depth and a second trench extending to a greater second depth are formed within the same device region. This nested configuration allows independent control of different device regions, enabling high device density while maintaining effective channel control to mitigate short channel effects
Solution Approach 2:
Selective epitaxial growth is performed in specific regions defined by the trench structure, creating local variations in material properties. This local quality control allows optimization of channel characteristics in critical regions while maintaining high device density overall, effectively managing short channel effects in specific device areas
3Power
If epitaxial structure volume is increased to improve current flow, then current flow increases, but device area increases
Solution Approach 1:
The patent utilizes vertical epitaxial growth within the trench structure to increase the epitaxial structure volume in the vertical dimension rather than expanding horizontally. This allows current flow to be enhanced through increased channel volume while maintaining compact device footprint, effectively decoupling current flow improvement from device area increase
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 operation speed and performance of FinFET devices by optimizing the epitaxial structure's volume and height, thereby addressing limitations in existing FinFET designs and fabrication methods.
Implementation Method 1
an epitaxial structure formed on the fin structure, the epitaxial structure having a controlled volume and height
Data Source
AI summary
A fin field effect transistor (FinFET) device structure and method for forming FinFET device structure are provided. The FinFET structure includes a substrate and an isolation structure formed on the substrate. The FinFET structure also includes a fin structure extending above the substrate, and the fin structure is embedded in the isolation structure. The FinFET structure further includes an epitaxial structure formed on the fin structure, the epitaxial structure has a pentagon-like shape, and an interface between the epitaxial structure and the fin structure is lower than a top surface of the isolation structure.