FinFET Fin Height Control via Multiple Etch Stop Layers
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Solution Overview
Problem
Existing FinFET manufacturing processes face challenges in achieving aspect ratios greater than three due to imprecision in etching fin height and width, leading to uneven angled implants and increased leakage current, which limits design options for circuits.
Innovation Solution
The use of multiple etch stop layers and compound layers with different band gap energies to selectively form fins of varying heights, allowing for enhanced control over fin heights and aspect ratios, thereby enabling the formation of FinFETs with aspect ratios greater than three.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional etching processes are used to form fins, then the manufacturing process is simple, but the fin height and width cannot be precisely controlled, limiting aspect ratio to less than three
Solution Approach 1:
The etching process is segmented into multiple stages with different etch stop layers (first etch stop layer, second etch stop layer) that allow independent control of fin height and width. The first etch stop layer controls fin height while the second etch stop layer controls fin width, enabling precise dimensional control without increasing overall process complexity
Solution Approach 2:
Etch stop layers are introduced as intermediary structures between the substrate and the fin structures. These intermediate layers (first etch stop layer, second etch stop layer) act as precise depth markers during etching, enabling accurate control of fin dimensions without requiring complex real-time monitoring
2Adaptability or versatility
If fin aspect ratio is increased beyond three, then design options for circuits are limited, but etching precision deteriorates and leakage current increases
Solution Approach 1:
The fin structure formation is segmented into height-controlled and width-controlled etching steps using different etch stop layers. This segmentation allows independent optimization of fin height and width, enabling high aspect ratios (greater than three) while maintaining precise dimensional control and avoiding the trade-off between aspect ratio and manufacturing precision
Solution Approach 2:
Different etching parameters are used for different etching steps: a first etching process with parameters optimized for vertical etching to achieve precise fin height control, and a second etching process with parameters optimized for lateral etching to achieve precise fin width control. This parameter differentiation enables high aspect ratios while maintaining manufacturing precision
3Length of stationary object
If fin aspect ratio is increased beyond three, then taller fins can be formed, but angled implants become uneven and leakage current increases
Solution Approach 1:
The implantation process is segmented into stages corresponding to different fin formation stages. By controlling fin height through the first etch stop layer before implantation, the fin geometry is standardized, ensuring uniform angled implants and reducing leakage current even at high aspect ratios
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 the manufacture of FinFETs with increased aspect ratios, expanding design options for circuits and reducing leakage current by using etch stop layers to regulate fin heights and employing materials like III-V and II-VI compounds to form effective fin structures.
Implementation Method 1
multiple etch stop layers and compound layers may be formed... By selectively etching individual fins to the first etch stop layer or to the second etch stop layer, a variety of fin heights may be formed. Because the etch stop layers regulate fin heights, increased aspect ratios (e.g., aspect ratios greater than 3) of fins may be achieved with enhanced control
Implementation Method 2
The first etch stop layer and the second etch stop layer may be formed using a first material having a first band gap energy. The first compound layer and the second compound layer may be formed using a second material having a second band gap energy that is less than the first band gap energy
Data Source
AI summary
An apparatus comprises a first fin field effect transistor (FinFET) device extending from a surface of a first etch stop layer. The apparatus also comprises a second FinFET device extending from a surface of a second etch stop layer. A first compound layer is interposed between the first etch stop layer and the second etch stop layer.