Silicon Nitride ALD Step Coverage Using PCDS Precursors
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Solution Overview
Problem
Existing methods for forming silicon nitride layers on substrates with high aspect ratios using atomic layer deposition (ALD) face challenges in achieving excellent step coverage and quality, particularly due to the use of organic silicon precursors that include carbon and nitrogen components, which can degrade the layer's quality.
Innovation Solution
The method employs pentachlorodisilane (PCDS) or diisopropylamine pentachlorodisilane (DPDC) as silicon precursors in an ALD process, purging unreacted gases with appropriate purge gases to form a silicon nitride layer with enhanced growth per cycle rate and superior step coverage, even at lower temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If organic silicon precursors containing carbon and nitrogen components are used in ALD process, then the formation of silicon nitride layer is achieved, but the layer quality deteriorates and step coverage is poor
Solution Approach 1:
The patent changes the chemical composition parameters of the silicon precursor from organic compounds (containing C and N) to inorganic compounds (PCDS or DPDC). This parameter change eliminates carbon contamination while maintaining effective silicon nitride layer formation, thereby resolving the contradiction between layer quality and step coverage
Solution Approach 2:
The patent adopts a proven ALD process framework using PCDS/DPDC precursors that has been demonstrated to achieve excellent step coverage, and applies it to silicon nitride layer formation. This copying of a successful process pattern from other semiconductor applications directly addresses the step coverage issue while maintaining layer quality
2Productivity
If traditional silicon precursors are used, then the formation process is simple, but the growth per cycle rate is low and step coverage is poor
Solution Approach 1:
The patent changes the precursor chemistry from traditional organic silicon compounds to PCDS/DPDC, which have fundamentally different reactivity characteristics. This parameter change enables both higher growth per cycle rates and superior step coverage, as the inorganic precursors provide better surface reaction efficiency and conformal deposition
Solution Approach 2:
The patent uses DPDC (diisopropylamine pentachlorodisilane) which combines organic and inorganic characteristics - the diisopropylamine group provides volatility and handling advantages while the pentachlorodisilane core provides the reactive silicon source. This composite approach achieves both high productivity and precision
3Reliability
If high temperature processing is used, then layer quality may improve, but the process complexity and energy consumption increase
Solution Approach 1:
The patent changes the precursor reactivity parameters to enable low-temperature deposition. PCDS and DPDC precursors are designed to be highly reactive at lower temperatures, eliminating the need for high thermal energy input while still achieving high-quality silicon nitride layers with excellent step coverage
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 a silicon nitride layer with excellent step coverage and quality, conformally formed on structures with high aspect ratios without voids, and improves the growth per cycle rate compared to traditional precursors, especially at temperatures below 350°C.
Implementation Method 1
forming a dielectric layer structure on the structure using an atomic layer deposition (ALD) method. Forming the first dielectric layer includes feeding a first gas including pentachlorodisilane (PCDS) or diisopropylamine pentachlorodisilane (DPDC) as a silicon precursor, and a second gas including nitrogen components into a chamber including the substrate such that the first dielectric layer is formed in situ on the structure having the height difference
Implementation Method 2
purging an unreacted portion of the first gas by feeding a first purge gas into the chamber
Implementation Method 3
purging an unreacted portion of the second gas by feeding a second purge gas into the chamber
Data Source
AI summary
A method for fabricating a semiconductor device includes forming a structure with a height difference on a substrate and forming a dielectric layer structure on the structure using an atomic layer deposition (ALD) method. Forming the dielectric layer structure includes forming a first dielectric layer including silicon nitride on the structure with the height difference. Forming the first dielectric layer includes feeding a first gas including pentachlorodisilane (PCDS) or diisopropylamine pentachlorodisilane (DPDC) as a silicon precursor, and a second gas including nitrogen components into a chamber including the substrate such that the first dielectric layer is formed in situ on the structure having the height difference.