Indium Nitride Thin Film Deposition via Atomic Layer Deposition
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Solution Overview
Problem
Current methods for manufacturing InN and GaN-based LEDs face challenges such as poor yield due to limited indium concentration and non-uniformity, leading to cumbersome device sorting and high costs, as existing deposition techniques like MOCVD are limited by high temperatures and diffusion issues.
Innovation Solution
The development of atomic layer deposition (ALD) methods for forming InN thin films, which involve alternating pulses of indium and nitrogen reactants in a reaction chamber, allowing for controlled deposition of epitaxial or single-crystal films at lower temperatures, thereby overcoming the limitations of MOCVD.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If MOCVD deposition is used with high temperature thermal cycling, then deposition speed is improved, but indium concentration uniformity deteriorates due to diffusion
Solution Approach 1:
The patent changes the deposition method from MOCVD to ALD, fundamentally altering the process parameters including temperature regime (avoiding high temperature thermal cycling), reaction mechanism (sequential surface reactions vs. simultaneous vapor deposition), and enabling precise control of indium concentration uniformity while maintaining acceptable deposition rates
Solution Approach 2:
The patent employs periodic pulsing of reactants in ALD process, where indium precursor and nitrogen-containing precursor are alternately introduced in controlled pulses, allowing sequential surface reactions that prevent diffusion-related non-uniformity while maintaining deposition efficiency
2Productivity
If high temperature deposition is used, then deposition rate is improved, but indium diffusion increases limiting maximum indium concentration
Solution Approach 1:
The patent changes the temperature parameter from high temperature (MOCVD) to lower temperature (ALD), preventing indium diffusion while enabling higher indium concentrations in the deposited film without thermal degradation or excessive diffusion
Solution Approach 2:
The patent replaces the thermal field-dominated MOCVD process with a chemically-controlled ALD process, where surface chemistry reactions dominate over thermal diffusion, enabling precise compositional control at lower temperatures
3Loss of time
If temperature variations inside substrate area occur, then deposition completes faster, but emission wavelength uniformity deteriorates
Solution Approach 1:
The patent changes from rapid high-temperature MOCVD to slower low-temperature ALD, where the sequential surface reaction mechanism makes deposition rate less sensitive to temperature variations, thereby improving wavelength uniformity across the substrate
Solution Approach 2:
The periodic pulsing of reactants in ALD creates self-limited surface reactions that are less sensitive to temperature gradients, ensuring uniform indium concentration and emission wavelength across the substrate area
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 reliable and controlled formation of InN thin films with precise composition and uniformity, improving the yield and reducing costs by minimizing temperature-related issues and achieving high-quality films for LED applications.
Implementation Method 1
providing a pulse of a first vapor phase In reactant into the reaction chamber to form no more than about a single molecular layer of the In reactant on the substrate
Implementation Method 2
providing a pulse of a second vapor phase reactant comprising N to the reaction chamber such that the second vapor phase reactant reacts with the In reactant on the substrate to form an InN containing thin film
Data Source
AI summary
Atomic layer deposition (ALD) processes for forming thin films comprising InN are provided. The thin films may find use, for example, in light-emitting diodes.