Thermal ALD Sub-Stoichiometric Metal-Oxide Films
Solution Overview
Problem
Current atomic layer deposition (ALD) techniques for suboxides are limited by the use of plasma, leading to incomplete, non-conformal, and non-uniform film deposition, and lack methods for forming conformal, uniform single metal ALD suboxides applicable to 3D technologies like flash and RRAMs without scavenging gates.
Innovation Solution
A fully thermal ALD process is developed, using mixed precursor reactions with the same metal but different ligands, where pulses of the first and second precursors are followed by an oxidant pulse, allowing for the formation of conformal and uniform sub-stoichiometric metal-oxide films without plasma, enabling their use in 3D technologies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If plasma-based ALD techniques are used for suboxide deposition, then deposition can proceed without scavenging gates, but the film deposition is incomplete, non-conformal, and non-uniform
Solution Approach 1:
The invention extracts and eliminates the plasma step from the ALD process, using only thermal cycles with mixed metalorganic precursors. This removes the harmful plasma-related issues while maintaining the ability to deposit suboxides without scavenging gates, achieving both ease of manufacture and manufacturing precision
Solution Approach 2:
The invention changes the deposition parameters by using mixed metalorganic precursors with different ligands in thermal cycles, adjusting temperature and pulse sequences to achieve complete, conformal, and uniform film deposition without plasma, thereby resolving the contradiction between ease of manufacture and manufacturing precision
2Manufacturing precision
If conventional ALD processes are used, then stoichiometric control is limited, but the process is simpler
Solution Approach 1:
The invention segments the deposition process into distinct thermal cycles with specific precursor sequences (first metalorganic precursor, then second metalorganic precursor with different ligands, followed by oxidant exposure). This segmentation enables precise stoichiometry control by independently managing each deposition step, achieving high manufacturing precision while maintaining reasonable process complexity through systematic organization
Solution Approach 2:
The invention employs periodic thermal cycles with alternating precursor pulses and oxidant exposure. This periodic action allows precise control over stoichiometry by repeating standardized cycle sequences, balancing manufacturing precision with process complexity through rhythmic, predictable process patterns
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 enables the deposition of conformal and uniform sub-stoichiometric metal-oxide films, suitable for 3D technologies, with the ability to tune stoichiometry and eliminate the need for plasma processes, enhancing the compatibility with current and future 3D technologies.
Implementation Method 1
the metal of the first precursor chemisorbs onto a surface of the substrate during the first pulse
Implementation Method 2
the metal of the second precursor chemisorbs onto a coated surface terminated by the first precursor ligands
Implementation Method 3
the first ligand and the second ligand react during the second pulse to form one or more by-products. In some embodiments of the invention, at least a portion of the one or more by-products are removing using off-gassing
Implementation Method 4
The substrate can be exposed to an oxidant during a third pulse of the ALD cycle
Data Source
AI summary
Embodiments of the present invention are directed to forming a sub-stoichiometric metal-oxide film using a modified atomic layer deposition (ALD) process. In a non-limiting embodiment of the invention, a first precursor and a second precursor are selected. The first precursor can include a metal and a first ligand. The second precursor can include the same metal and a second ligand. A substrate can be exposed to the first precursor during a first pulse of an ALD cycle. The substrate can be exposed to the second precursor during a second pulse of the ALD cycle. The second pulse can occur directly after the first pulse without an intervening thermal oxidant. The substrate can be exposed to the thermal oxidant during a third pulse of the ALD cycle.