Tungsten Thin-Film Precursors for Precise ALD Thickness Control
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Solution Overview
Problem
Existing methods for forming tungsten-containing thin films, such as WO3, WNx, WS2, and WS2, are inefficient and lack control over film thickness and uniformity, particularly in atomic layer deposition (ALD) and chemical vapor deposition (CVD) processes.
Innovation Solution
A process involving alternating and sequential contact of a substrate with vapor phase W precursors, such as W(IV) beta-diketonates, and chalcogen precursors like H2S, H2Se, in controlled ALD or CVD cycles, ensuring self-limiting monolayer deposition and precise film thickness control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional vapor deposition methods are used to form tungsten-containing thin films, then film formation is achieved, but manufacturing precision and control over film thickness are poor
Solution Approach 1:
The deposition process is divided into sequential cycles where a tungsten precursor is exposed, followed by a chalcogen precursor exposure. This segmentation allows precise control over the deposition of tungsten-containing films by forming them layer by layer through alternating precursor exposures, achieving both manufacturing precision and acceptable productivity.
Solution Approach 2:
The patent employs periodic alternating exposure to tungsten precursor and chalcogen precursor in cyclic sequences. This periodic action enables controlled formation of tungsten-containing thin films with precise thickness control, as each cycle deposits a controlled amount of material that can be accumulated to achieve desired film thickness.
2Ease of manufacture
If vapor phase precursors are used for deposition, then deposition process is simplified, but control over reaction byproducts and film uniformity is insufficient
Solution Approach 1:
The patent incorporates purge steps between precursor exposures that remove reaction byproducts from the reaction chamber. This feedback mechanism ensures that byproducts do not interfere with subsequent deposition cycles, maintaining film uniformity and composition control while preserving the simplicity of vapor phase processing.
Solution Approach 2:
Purge gas acts as an intermediary that removes reaction byproducts between deposition steps. This intermediary function allows the main deposition process to remain simple while ensuring precise control over film uniformity by preventing byproduct accumulation that would otherwise degrade film quality.
3Device complexity
If single precursor exposure is used, then process steps are reduced, but inability to form controlled thin films with desired composition
Solution Approach 1:
The deposition process segments tungsten and chalcogen precursor exposures into separate sequential steps. This segmentation enables precise control over film composition by allowing independent control of tungsten deposition and chalcogen addition, forming controlled thin films with desired stoichiometry while keeping each individual step relatively simple.
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
Achieves uniform and controlled deposition of tungsten-containing thin films with precise thickness, enhancing their suitability for applications in microelectronics and other devices.
Implementation Method 1
contacting the substrate with a vapor phase W precursor such that at most a molecular monolayer of W containing species is formed on the substrate surface
Implementation Method 2
contacting the substrate with a vapor phase second precursor, and optionally repeating the two contacting steps until a W containing thin film of the desired thickness is formed
Data Source
AI summary
Methods are provided for synthesizing W(IV) beta-diketonate precursors. Additionally, methods are provided for forming W containing thin films, such as WS2, WNx, WO3, and W via vapor deposition processes, such as atomic layer deposition (ALD) type processes and chemical vapor deposition (CVD) type processes. Methods are also provided for forming 2D materials containing W.