Mist-CVD Oxide Film Deposition With Partitioned Gas Flow
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Solution Overview
Problem
The mist-CVD method faces challenges with particle generation and contamination due to mist flocculation and external air ingress, leading to poor film quality and productivity, particularly in forming high-quality crystalline oxide films.
Innovation Solution
A film-forming method and apparatus that utilize a partitioned film-forming chamber with a carrier gas and additional gas feed, along with a gas-discharging mechanism, to reduce particle density and improve film quality, using a mist-CVD process to form crystalline oxide films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the mist-CVD method is used to form oxide semiconductor films, then film formation capability is achieved, but particle generation occurs due to mist flocculation and product release
Solution Approach 1:
The film-forming chamber is divided into multiple regions by partition walls, creating a first film-forming region for mist supply and a second film-forming region for separate gas supply. This segmentation prevents mist flocculation throughout the entire chamber while maintaining film formation capability in the first region.
Solution Approach 2:
A carrier gas is introduced as an intermediary substance to transport the mist from the mist-generating member to the substrate. The carrier gas prevents direct contact and flocculation of mist particles while enabling controlled deposition on the substrate surface.
2Productivity
If a large amount of mist is supplied to increase film-forming rate, then productivity improves, but particle adhesion to the film increases
Solution Approach 1:
Different regions of the film-forming chamber are assigned different gas flow characteristics. The first film-forming region receives controlled mist-laden carrier gas for film deposition, while the second film-forming region receives additional carrier gas to maintain low particle density and prevent flocculation, enabling high film-forming rates without compromising film quality.
Solution Approach 2:
The system controls particle density parameters by adjusting gas flow rates and mist supply conditions. By maintaining particle density at 100000/m3 or less through parameter optimization, the system achieves both high film-forming rates and low particle adhesion.
3Stability of the object's composition
If negative pressure is applied to disperse mist in the film-forming chamber, then mist dispersion improves, but external air flows in causing film contamination
Solution Approach 1:
Instead of applying negative pressure to achieve mist dispersion, the system uses positive pressure by supplying carrier gas from the second film-forming region. This inverted approach disperses mist through gas flow while preventing external air ingress that would cause contamination.
4Length of moving object
If film-forming time is lengthened to thicken the film, then film thickness increases, but mist flocculation and product release become new particle generation sources
Solution Approach 1:
The system establishes proper mist dispersion and carrier gas flow conditions before film formation begins. By pre-configuring the gas flow fields in both film-forming regions, the system prevents mist flocculation and product release throughout the extended film-forming process, enabling thick film formation without particle generation.
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 high-quality crystalline oxide films with significantly reduced particle density and improved safety, suitable for large-area substrates, enhancing film uniformity and reducing defects.
Implementation Method 1
a mist-generating member configured to atomize a raw material into a mist
Implementation Method 2
a substrate heating means for heating the substrate
Implementation Method 3
supplying a mist together with a carrier gas onto a heated substrate
Implementation Method 4
in a film-forming member covered with a partition wall
Data Source
AI summary
A film-forming method for forming a crystalline oxide film by a mist-CVD method includes: 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.