Double-Tube Plasma Nozzle Layout for Uniform Film Deposition
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Solution Overview
Problem
Existing film forming devices with double tube structures face issues such as premature deposition of raw material gas within the tubes, trapping of active species, and non-uniform plasma distribution, leading to decreased decomposition efficiency and film quality.
Innovation Solution
A film forming device with a coaxial double tube structure, where the second electrode is positioned downstream of the first electrode, and a third electrode is applied on the substrate to enhance plasma distribution and decomposition, ensuring a longer path for plasma energy and improved radial and circumferential spread, thereby maintaining active species propagation and film quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the ground electrode is disposed on the downstream side with respect to the high voltage application electrode in a double tube structure, then the device configuration is simplified, but active species (mainly positive ions) are trapped in the ground electrode before reaching the discharge port, decreasing the amount of decomposition of raw material gas and lowering film purity
Solution Approach 1:
The patent inverts the conventional electrode arrangement by placing the high voltage application electrode on the downstream side and the ground electrode on the upstream side. This inversion prevents positive ions from being trapped in the ground electrode before reaching the discharge port, ensuring they can decompose the raw material gas effectively and maintain film purity.
2Power
If plasma is generated between the high voltage electrode and ground electrode, then decomposition of raw material gas is promoted, but the ignition is local discharge in a form of lightning, causing non-uniform plasma distribution at the discharge port and decreasing decomposition efficiency
Solution Approach 1:
The patent introduces a circumferential direction dimension by arranging multiple high voltage application electrodes around the outer tube at different circumferential positions. This transforms the plasma generation from a single-point local discharge to a distributed three-dimensional plasma field, achieving uniform plasma distribution throughout the tube while maintaining high decomposition efficiency.
3Device complexity
If a single tube structure is used for the nozzle, then the device configuration is simplified, but deposition occurs due to decomposition of raw material gas in the tube, and discharge cannot be performed for a long time
Solution Approach 1:
The patent segments the nozzle into a double tube structure with an inner tube and an outer tube. The inner tube transports raw material gas while the outer tube generates plasma. This segmentation prevents direct contact between raw material gas and the tube wall, avoiding deposition and extending discharge duration while maintaining structural simplicity.
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 configuration enhances the decomposition efficiency of raw material gas, improves film purity, and maintains film quality by ensuring uniform plasma distribution and prolonged exposure to active species, resulting in a higher-quality film.
Implementation Method 1
plasma-generating gas flows through an outer tube. The plasma-generating gas is guided to a downstream discharge port as a plasma by discharge generated by a pair of electrodes (ground electrode and high voltage application electrode) disposed around the outer tube
Implementation Method 2
The plasma is gas containing active species such as charged particles (ions, electrons, and the like) and radicals. At the discharge port, the plasma merges with the raw material gas to decompose the raw material gas
Implementation Method 3
The product discharged toward a surface of the substrate is deposited to form a film
Data Source
AI summary
Provided is a film forming device that deposits, on a substrate, a product generated by decomposing raw material gas by a plasma discharged from a discharge port of a double tube, the device including: an inner tube through which raw material gas containing a film-forming raw material flows and is guided to the discharge port on a downstream side; an outer tube that has the inner tube inserted thereinto and through which plasma-generating gas flows and a plasma generated by discharge is guided to the discharge port on the downstream side; a first electrode that is formed in an annular shape around the outer tube and grounded; and a second electrode that is formed in an annular shape around the outer tube and to which a voltage is applied. The second electrode is disposed on the downstream side with respect to the first electrode, and assuming that a length of the second electrode in an axial direction is L1 and a diameter of the outer tube is D1, a relationship of L1≥D1 is satisfied.