Mist CVD Flow Regulation for Uniform Oxide Semiconductor Films
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Solution Overview
Problem
The mist CVD method faces challenges in maintaining in-plane uniformity of film thickness distribution due to thermal convection and gas flow disturbances, leading to poor film quality and increased fabrication steps in semiconductor device production.
Innovation Solution
A film forming apparatus and method that includes an atomizer, carrier gas supplier, and a film forming unit with a substrate holder, nozzle, ceiling plate, and sidewalls to regulate mist flow, ensuring a difference in height position and shortest distance between the substrate holder and sidewalls is within specific limits, promoting uniform gas flow and film formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mist is supplied from above the substrate using conventional mist CVD apparatus, then film formation is achieved, but thermal convection and gas flow disturbances occur causing poor in-plane uniformity of film thickness distribution
Solution Approach 1:
The invention introduces a ceiling plate positioned above the substrate at a specific height (I cm) to create a three-dimensional flow regulation structure. This ceiling plate, combined with sidewalls at distance J cm from the substrate, forms a confined space that guides mist flow in a controlled trajectory, transforming the uncontrolled vertical deposition into a regulated multi-dimensional flow pattern that enhances uniformity across the substrate surface.
Solution Approach 2:
The invention optimizes specific geometric parameters I and J (where IJ ≤ 15) to control the mist flow characteristics. By adjusting the height of the ceiling plate (I) and the distance of sidewalls from the substrate (J), the gas flow velocity, temperature distribution, and mist concentration are regulated to minimize thermal convection effects and achieve uniform film thickness across the substrate.
2Productivity
If substrate size is increased to 6-inch diameter for large-area film formation, then production capacity is improved, but in-plane uniformity of film thickness distribution deteriorates further
Solution Approach 1:
The invention divides the large substrate area into uniformly covered zones by introducing ceiling plates and sidewalls that create segmented flow channels. This segmentation of the gas flow path ensures that mist is distributed evenly across the entire 6-inch substrate surface, preventing center-thick edge-thin profiles and maintaining uniformity even over large areas.
Solution Approach 2:
The ceiling plate and sidewalls act as intermediary structures that mediate between the mist source and the large substrate surface. These intermediaries regulate and redistribute the mist flow, ensuring uniform coverage across the extended 6-inch substrate area by controlling the flow dynamics in the space between the nozzle and substrate.
3Manufacturing precision
If conventional mist CVD apparatus is used without flow regulation structures, then device complexity is reduced, but film quality and yield are compromised due to poor uniformity
Solution Approach 1:
The invention applies flow regulation structures (ceiling plate and sidewalls) locally at critical positions around the substrate perimeter and above it, rather than complicating the entire apparatus. This localized approach regulates mist flow where it is most needed to achieve uniformity, while keeping the rest of the system relatively simple and easy to manufacture.
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 solution achieves excellent in-plane uniformity of film thickness distribution, reducing the number of semiconductor device fabrication steps and increasing yield by stabilizing the mist flow and film formation process.
Implementation Method 1
an atomizer configured to atomize a raw material solution to generate a mist
Implementation Method 2
a carrier gas supplier configured to supply a carrier gas that conveys the mist generated by the atomizer
Implementation Method 3
a film forming unit configured to heat the mist conveyed by the carrier gas to form a film
Implementation Method 4
a ceiling plate located above the substrate holder and configured to regulate a flow of the mist supplied from the nozzle
Data Source
AI summary
A film forming apparatus includes: an atomizer to atomize a raw material solution to generate a mist; a carrier gas supplier to supply a carrier gas that conveys the mist; and a film forming unit to heat the mist conveyed by the carrier gas to form a film. The film forming unit includes a substrate holder to hold the substrate, a nozzle located above the substrate holder to supply the mist onto the substrate, a ceiling plate located above the substrate holder to regulate a flow of the mist supplied from the nozzle, and sidewalls facing each other with the substrate holder interposed. When a height difference position between a substrate holding surface of the substrate holder and a bottom surface of the ceiling plate is I and a shortest distance between a substrate holding region of the substrate holder and each of the sidewalls is J, IJ≤15.