2D Vertical Fin Structure With Sharp Corners for Uniform Fin Channels
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Solution Overview
Problem
Existing FinFET devices with one-dimensional vertical fins have variations in fin channel thickness and device performance due to rounded corners at the intersection of perpendicular arms, affecting transistor efficiency and consistency.
Innovation Solution
A 2-step process involving annealing to reduce irregularity and crystal-plane selective etching to form atomically sharp corners at the intersection of perpendicular arms, creating a two-dimensional vertical fin with intersecting arms that form a cross, fence, or lattice structure, thereby reducing corner rounding and enhancing device geometry consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used to form vertical fins, then the fabrication process is simple, but the fin channel thickness varies due to rounded corners at arm intersections
Solution Approach 1:
The method performs preliminary actions by first forming irregular openings with rounded corners, then applying heat treatment to reduce surface area and create more regular shapes, and finally using crystal-plane selective etching to form sharp corners. This sequence of preliminary actions prepares the structure in advance to achieve the desired sharp corners and consistent fin channel thickness in the final vertical fins.
Solution Approach 2:
The method changes physical and chemical parameters through heat treatment (changing temperature parameters) to reduce the surface area of irregular openings, and through crystal-plane selective etching (changing chemical etching parameters) to form sharp corners. These parameter changes transform the rounded-corner openings into squared openings with atomically sharp corners, resolving the contradiction between manufacturing precision and process complexity.
2Productivity
If rounded corners are present at arm intersections, then the fabrication process is simpler, but the effective transistor width and drive current are reduced
Solution Approach 1:
The method changes the physical state and chemical properties of the opening structures through heat treatment and crystal-plane selective etching. The heat treatment modifies the surface energy and shape parameters, while the selective etching changes the geometric parameters to create atomically sharp corners. These parameter changes increase the effective transistor width and drive current by eliminating corner rounding.
3Manufacturing precision
If heat treatment and crystal-plane selective etching are applied, then corner sharpness and fin channel consistency are improved, but the fabrication process becomes more complex
Solution Approach 1:
The method uses preliminary heat treatment to reduce the surface area of irregular openings and create more regular shapes before the final etching step. This preliminary action simplifies the subsequent crystal-plane selective etching process by providing a more uniform starting structure, thereby balancing the trade-off between manufacturing precision and fabrication ease.
Solution Approach 2:
The crystal-plane selective etching process exploits the self-aligned nature of crystal planes to automatically form sharp corners at the intersections of perpendicular arms. The etching process itself serves to create the desired geometry without requiring additional alignment steps or complex tooling, improving ease of manufacture while maintaining high precision.
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
The method improves the consistency of fin channel thickness and device performance by forming sharp corners, increasing the effective transistor width and drive current while maintaining a compact chip footprint.
Implementation Method 1
heat treating a periodic array of irregular openings in a substrate, wherein there are walls of substrate material between adjacent openings, to reduce the surface area of the openings
Implementation Method 2
etching the openings with a crystal-plane selective etch to form squared openings in the substrate
Data Source
AI summary
A method of forming a two dimensional (2D) vertical fin is provided. The method includes heat treating a periodic array of irregular openings in a substrate, wherein there are walls of substrate material between adjacent openings, to reduce the surface area of the openings, and etching the openings with a crystal-plane selective etch to form squared openings in the substrate.