Plasma ALD Residence-Time Control for Low-Impurity Silicon Nitride
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Solution Overview
Problem
Conventional plasma atomic layer deposition (ALD) techniques face challenges in achieving high-quality films, particularly dielectric films like silicon nitrides, due to poor film density and high impurity levels, which are often exacerbated by prolonged exposure to reactants and plasma phases.
Innovation Solution
Modulating the residence time of excited species in the reaction space during the plasma phase of the ALD process, ensuring it is less than 1.0 s, to enhance film quality by reducing impurities and increasing density, while maintaining conformal deposition characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If prolonged exposure to plasma phase is used in conventional plasma ALD, then reaction completeness is improved, but film density decreases and impurity levels increase
Solution Approach 1:
The patent changes the residence time parameter of excited species in the reaction space from conventional prolonged exposure to less than 1.0 second. This parameter modification resolves the contradiction by achieving complete surface reactions without the harmful effects of prolonged plasma exposure, thereby maintaining high film density while ensuring reaction completeness.
Solution Approach 2:
The patent introduces dynamic control of plasma phase timing, adjusting the residence time of excited species based on process requirements. By making the plasma exposure duration a controllable variable rather than a fixed prolonged period, the system can optimize both reaction completeness and film quality simultaneously.
2Reliability
If prolonged exposure to plasma phase is used in conventional plasma ALD, then reaction completeness is improved, but impurity levels increase
Solution Approach 1:
The patent modifies the residence time parameter to less than 1.0 second, which eliminates the generation of impurities during plasma exposure while maintaining complete surface reactions. This parameter change directly addresses the contradiction by preventing harmful side reactions that occur during prolonged plasma exposure.
Solution Approach 2:
The patent rushes through the plasma phase with a residence time of less than 1.0 second, completing the necessary surface reactions quickly before impurities can form. This approach skips the harmful prolonged exposure period while still achieving the desired reaction completeness.
3Ease of manufacture
If conventional plasma ALD techniques are used, then deposition process is simplified, but film quality (density and purity) deteriorates
Solution Approach 1:
The patent maintains the simplicity of the plasma ALD process while improving film quality by changing only the residence time parameter to less than 1.0 second. This minimal parameter modification preserves process ease of manufacture while dramatically improving film density and purity.
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 results in higher-quality films with reduced impurity levels and improved density, achieving conformal layers over complex topographies with enhanced step coverage and reduced wet etch rates, outperforming traditional deposition methods.
Implementation Method 1
the substrate is contacted with a silicon precursor to adsorb an adsorbed species of the silicon precursor on the substrate
Implementation Method 2
the substrate is contacted with excited nitrogen species to react with the adsorbed species
Implementation Method 3
the substrate is contacted with excited nitrogen species supplied to or formed in the reaction space
Data Source
AI summary
Plasma atomic layer deposition (ALD) is optimized through modulation of the gas residence time during an excited species phase, wherein activated reactant is supplied such as from a plasma. Reduced residence time increases the quality of the deposited layer, such as reducing wet etch rates, increasing index of refraction and/or reducing impurities in the layer. For example, dielectric layers, particularly silicon nitride films, formed from such optimized plasma ALD processes have low levels of impurities remaining from the silicon precursor.