TMDC Thin Film ALD Cycles for Thickness and Uniformity Control
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Solution Overview
Problem
Existing methods for depositing transition metal dichalcogenide (TMDC) films, such as rhenium sulfide, are inefficient and lack control over film thickness and uniformity, particularly in forming two-dimensional materials for advanced applications like logic devices and lithium-ion batteries.
Innovation Solution
Atomic layer deposition (ALD) and chemical vapor deposition (CVD) processes are utilized, involving alternating contact of a substrate with transition metal precursors, reducing agents, and chalcogenide precursors, with controlled removal of excess reactants and byproducts to achieve precise film thickness and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If vapor deposition processes are used to deposit TMDC films, then films can be formed for various applications, but the efficiency and control over film thickness and uniformity are insufficient
Solution Approach 1:
The deposition process is divided into multiple sequential half-cycles, where each half-cycle deposits a portion of the final film thickness. This segmentation allows precise control over total thickness by adjusting the number of half-cycles, while maintaining high efficiency through automated sequential processing without intermediate manual interventions.
Solution Approach 2:
The method employs periodic alternation between different vapor phase reactants (first reactant containing transition metal precursor, second reactant containing chalcogenide precursor) in a cyclic deposition process. This periodic action enables precise thickness control through controlled number of cycles while maintaining high deposition efficiency through continuous automated processing.
2Manufacturing precision
If vapor deposition processes are used to deposit TMDC films, then films can be formed for various applications, but uniformity and impurity control are insufficient
Solution Approach 1:
The deposition is conducted in an inert atmosphere using purified vapor phase reactants, preventing unwanted chemical reactions and impurity formation during the deposition process. This inert environment ensures high film uniformity and minimizes contaminant incorporation throughout the multiple deposition half-cycles.
Solution Approach 2:
By dividing the deposition into sequential half-cycles with intermediate purge steps, the process segments the film formation into controlled stages. Each half-cycle deposits material with high uniformity, and the intermediate purges remove excess reactants and byproducts, preventing impurity accumulation and ensuring overall film uniformity.
3Manufacturing precision
If multiple deposition cycles are performed to achieve desired thickness, then film thickness can be controlled, but processing time increases
Solution Approach 1:
The deposition process maintains continuity by automatically sequencing multiple half-cycles without manual intervention between cycles. The reactor continuously alternates between exposing the substrate to first and second vapor phase reactants, eliminating idle time and maintaining productive action throughout the entire multi-cycle deposition process.
Solution Approach 2:
The method uses optimized periodic cycles where the duration and frequency of reactant exposure are precisely controlled. By adjusting the number and timing of periodic half-cycles, the process achieves desired thickness precision while minimizing total processing time through efficient cycle optimization.
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 enables the deposition of high-quality, thin TMDC films with controlled thickness and uniformity, suitable for applications in 2D materials, logic devices, and lithium-ion batteries, with reduced impurities and improved step coverage.
Implementation Method 1
Atomic layer deposition (ALD) and chemical vapor deposition (CVD) processes are utilized, involving alternating contact of a substrate with transition metal precursors, reducing agents, and chalcogenide precursors
Implementation Method 2
Excess reactants and byproducts are purged from the substrate surface
Implementation Method 3
chemical vapor etching methods for etching such films
Data Source
AI summary
Vapor deposition methods for depositing transition metal dichalcogenide (TMDC) films, such as rhenium sulfide thin films, are provided. In some embodiments TMDC thin films are deposited using a deposition cycle in which a substrate in a reaction space is alternately and sequentially contacted with a vapor phase transition metal precursor, such as a transition metal halide, a reactant comprising a reducing agent, such as NH3 and a chalcogenide precursor. In some embodiments rhenium sulfide thin films are deposited using a vapor phase rhenium halide precursor, a reducing agent and a sulfur precursor. The deposited TMDC films can be etched by chemical vapor etching using an oxidant such as O2 as the etching reactant and an inert gas such as N2 to remove excess etching reactant. The TMDC thin films may find use, for example, as 2D materials.