Mist-CVD Oxide Film Deposition with Partitioned Gas Flow
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Solution Overview
Problem
The mist-CVD method faces challenges with particle flocculation and contamination due to mist adherence to chamber walls, leading to poor film quality and productivity, and external air contamination from negative chamber pressure.
Innovation Solution
A film-forming method and apparatus that supply a mist with a carrier gas into a partitioned chamber, using a gas other than the carrier gas to reduce particle density, and incorporate a gas-discharging member to maintain chamber cleanliness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the mist-CVD method is used to form a film, then the film-forming rate can be increased, but particle density on the film surface increases due to mist flocculation and adhesion
Solution Approach 1:
The invention divides the film-forming chamber into multiple regions using partition walls, creating distinct zones for mist supply, film formation, and particle removal. This segmentation allows the mist to be supplied in a controlled manner while preventing flocculation and facilitating particle removal, thus maintaining both high film-forming rate and low particle density
Solution Approach 2:
The invention extracts harmful particles from the film-forming environment by introducing a gas flow that selectively removes particles from the chamber. This extraction mechanism prevents particles from adhering to the film surface while maintaining the mist supply for continuous film formation
2Productivity
If the film-forming time is extended to thicken the film, then productivity is improved, but mist flocculation and product release from wall surfaces increase particle generation
Solution Approach 1:
The invention applies preliminary action by introducing a gas flow before mist flocculation occurs. This preventive gas flow keeps particles suspended and prevents them from adhering to wall surfaces, thereby eliminating the source of particle generation during extended film-forming operations
Solution Approach 2:
The invention converts the potentially harmful effect of extended film-forming time (which causes flocculation) into a benefit by using the extended time to allow continuous gas flow to remove particles. The longer operation time enables thorough particle removal while maintaining film quality
3Stability of the object's composition
If negative pressure is applied in the film-forming chamber to disperse mist, then mist dispersion is improved, but external air contamination increases particle density
Solution Approach 1:
The invention inverts the pressure approach by applying positive pressure instead of negative pressure. This positive pressure prevents external air infiltration while still achieving effective mist dispersion through the introduced gas flow, thereby eliminating the contamination problem associated with negative pressure
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 method and apparatus produce a high-quality crystalline oxide film with significantly reduced particle density and improved safety, suitable for large-area substrates.
Implementation Method 1
supplying a mist together with a carrier gas onto a heated substrate
Implementation Method 2
in a film-forming member covered with a partition wall
Implementation Method 3
in at least heating the substrate, a gas other than the carrier gas is fed into the film-forming member
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The present invention is a film-forming method for forming a crystalline oxide film by a mist-CVD method, the method including: supplying a mist together with a carrier gas onto a heated substrate in a film-forming member covered with a partition wall, wherein, in at least heating the substrate, a gas other than the carrier gas is fed into the film-forming member. This provides a film-forming method to form a high-quality crystalline oxide film having a remarkably reduced particle density on a film surface.