Doped Hafnium Oxide Thin Films With Precise ALD Dopant Tuning
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Solution Overview
Problem
Conventional methods for depositing doped hafnium oxide films struggle to achieve finely controlled dopant concentrations, limiting the ferroelectric properties of these films, which are crucial for advanced electronic devices.
Innovation Solution
A method involving sequential exposure of a substrate to hafnium and dopant precursors, followed by oxidation, is used to form doped hafnium oxide films. This process allows for precise control of dopant concentration in each monolayer, enabling tunability down to 1.5 mol%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional ALD method inserting nearly complete monolayers of dopant film is used, then deposition process is simple, but dopant concentration control is coarse (integer multiples of 3-5 mol%)
Solution Approach 1:
The dopant deposition process is segmented into multiple sequential ALD cycles, where the dopant precursor is introduced for only a portion of the cycle (e.g., 1-2 cycles out of a 5-cycle sequence). This segmentation allows precise control of dopant concentration by adjusting the frequency and duration of dopant precursor exposure, achieving fine-tuned doping levels (e.g., 1.5-9 mol%) rather than coarse integer multiples.
2Reliability
If dopant concentration is increased to achieve ferroelectricity, then ferroelectric properties are enhanced, but film thickness must be maintained at 2 nm or less
Solution Approach 1:
The invention changes the dopant concentration parameter precisely through controlled ALD cycling to achieve the minimum required doping level for ferroelectricity in ultra-thin films. By optimizing the dopant introduction frequency and duration within the ALD sequence, the patent achieves ferroelectric properties at the lowest possible thickness (2 nm or less), thereby maximizing the electric field effect while maintaining functional performance.
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 achieves superior control over the ferroelectricity of doped hafnium oxide films, allowing for multiple achievable doping levels in the range of 1.5 to 9 mol%, which is essential for optimizing the performance of thin films in electronic devices.
Implementation Method 1
exposing the substrate to a first oxidant to react with the hafnium-containing monolayer to form a hafnium oxide monolayer
Implementation Method 2
exposing the substrate to a dopant precursor to deposit a dopant-containing layer on the substrate with the second hafnium-containing monolayer
Data Source
AI summary
Methods of depositing thin films of hafnium oxide possessing strong ferroelectric properties are described. A hafnium oxide monolayer is formed in a first process cycle comprising sequential exposure of a substrate to a hafnium precursor, purge gas, first oxidant and purge gas. A doped hafnium oxide monolayer is formed in a second process cycle comprising sequential exposure of the substrate to a hafnium precursor, purge gas, dopant precursor, purge gas, second oxidant and purge gas. Thin films of hafnium oxide are also described.