Zinc Oxide Coating CVD Process for Glass Substrates
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Solution Overview
Problem
Existing processes for depositing zinc oxide coatings on glass substrates are limited, often damaging pre-existing coatings and restricting the layers over which zinc oxide can be deposited, necessitating a more robust method for forming high-quality zinc oxide coatings.
Innovation Solution
A chemical vapor deposition (CVD) process involving a moving glass substrate, where a fluorine doped tin oxide coating is applied first, followed by a gaseous mixture of an alkyl zinc compound, inert gas, and inorganic oxygen-containing compounds, with separate streams being directed through a coating apparatus to form a zinc oxide coating of specific thickness and quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If known processes are used to deposit zinc oxide coatings, then zinc oxide coating can be formed, but pre-existing coating layers are damaged and the process is not robust
Solution Approach 1:
The patent changes the chemical parameters of the deposition process by using separate gaseous streams that are mixed at or near the substrate surface. This controlled parameter change allows zinc oxide deposition without damaging underlying conductive coatings, resolving the contradiction between forming zinc oxide coating and protecting pre-existing layers
Solution Approach 2:
The patent introduces an intermediary mixing zone where gaseous zinc-containing compounds and oxygen-containing compounds are mixed before reaching the substrate. This intermediary step prevents direct harmful interaction with pre-existing coatings while enabling controlled zinc oxide formation, thus protecting underlying layers
2Quantity of substance
If zinc oxide coating is deposited over conductive tin oxide coating, then zinc oxide layer can be formed, but sheet resistance increases significantly
Solution Approach 1:
The patent uses controlled partial action by limiting the zinc oxide deposition to a thin layer (up to 100 nm) through controlled gaseous stream mixing. This partial deposition provides the desired zinc oxide coating while maintaining the underlying conductive tin oxide layer's electrical properties, preventing significant sheet resistance increase
Solution Approach 2:
The patent applies local quality by creating a thin zinc oxide layer with specific properties through controlled gas mixing. The zinc oxide coating is deposited only to the extent needed (up to 100 nm) to achieve desired optical or functional properties without compromising the electrical conductivity of the underlying tin oxide layer
3Manufacturing precision
If known deposition methods are used, then zinc oxide coating can be deposited, but thickness uniformity is poor
Solution Approach 1:
The patent segments the deposition process into separate gaseous streams that are mixed at or near the substrate surface. This segmentation of the gas delivery system allows precise control over the deposition chemistry, resulting in excellent thickness uniformity across the substrate while maintaining ease of manufacture through a straightforward multi-stream delivery approach
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 CVD process enables the formation of high-quality zinc oxide coatings with excellent thickness uniformity and maintains the low sheet resistance of the coated glass article, even when deposited over conductive tin oxide coatings, preventing significant increases in sheet resistance.
Implementation Method 1
a chemical vapor deposition (CVD) process for depositing a zinc oxide coating
Implementation Method 2
the first and second streams are kept separate prior to mixing the gaseous streams at or near a surface of the moving glass substrate
Implementation Method 3
the zinc oxide coating is preferably a pyrolytic coating
Data Source
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AI summary
A CVD process for depositing a zinc oxide coating is provided. The CVD process includes providing a moving glass substrate. The CVD process also includes forming a gaseous mixture of an alkyl zinc compound and an inert gas as a first stream, providing a first gaseous inorganic oxygen-containing compound in a second stream and providing a second gaseous inorganic oxygen-containing compound in the second stream, a third stream or in both the second and third streams. Additionally, the CVD process includes mixing the streams at or near a surface of the moving glass substrate and a zinc oxide coating is formed thereon. A method for forming a coated glass article is also provided. Additionally, a coated glass article is provided.