TiO2 Coating Film on Glass Substrate via Low Temperature Plasma CVD
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Solution Overview
Problem
Existing methods for producing glass substrates with high refractive index titania layers face challenges such as cracking during heat treatment and insufficient optical performance, particularly when using titanium oxide layers formed by sputtering or other methods.
Innovation Solution
A method involving the low temperature plasma CVD technique to form TiO2-containing layers with a refractive index of at least 2.20, using alkoxide or amide type titanium materials, and subjecting the layers to heat treatment between 600°C to 700°C to achieve high heat resistance and desired optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a titanium oxide layer is formed by sputtering method, then the refractive index is high, but cracking occurs during heat treatment
Solution Approach 1:
The patent changes the formation method parameter from sputtering to plasma CVD, and controls the plasma power density within a specific range (40-80 kW/m) to form a titanium oxide layer with high refractive index that does not crack during heat treatment. This parameter change resolves the contradiction between achieving high refractive index and preventing heat treatment cracking.
Solution Approach 2:
The patent replaces the mechanical sputtering process with a plasma-based chemical vapor deposition process. This substitution allows for better control of film formation, resulting in a titanium oxide layer with superior heat resistance while maintaining the required optical properties.
2Illumination intensity
If the number of layers to be laminated is large, then the optical performance is improved, but the production cost increases
Solution Approach 1:
The patent segments the coating into multiple layers with different functions: a titanium oxide layer for high refractive index and optical performance, and a silicon oxide layer for adhesion and flexibility. This segmentation allows achieving excellent optical performance with only two layers instead of many layers, thereby reducing production cost.
Solution Approach 2:
The patent uses a composite structure combining titanium oxide and silicon oxide layers. The titanium oxide provides the required optical properties (high refractive index), while the silicon oxide provides adhesion to the glass substrate and flexibility during heat treatment. This composite approach achieves excellent optical performance with reduced complexity and lower production cost.
3Ease of manufacture
If a single layer film is used, then the production cost is reduced, but the optical performance is insufficient
Solution Approach 1:
The patent employs a composite material structure with two layers: titanium oxide for high refractive index and optical performance, and silicon oxide for adhesion and flexibility. This composite approach enables achieving excellent optical performance with only two layers, maintaining cost-effectiveness while significantly improving optical properties compared to single layer films.
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 produces glass substrates with TiO2 layers that exhibit excellent heat resistance and optical properties, preventing cracking during heat treatment and providing desired optical functions like antireflection or infrared reflection.
Implementation Method 1
forming a TiO2-containing layer on a glass substrate by low temperature plasma CVD method
Implementation Method 2
applying an electric power to a plasma source by a power source to cause a plasma power density of at least 55 kW/m
Data Source
Figure 1~2
Figure 3
AI summary
To provide a glass substrate provided with a coating film having a high refractive index titania layer which is excellent in the heat resistance with cracking or the like by heat treatment suppressed, and a method for producing such a glass substrate provided with a coating film. A glass substrate provide with a coating film, comprising a glass substrate and a coating film containing at least one TiO2 layer having a refractive index of at least 2.20 at a wavelength of 632 nm, formed by low temperature plasma CVD method on the glass substrate, and a method for producing a glass substrate provided with a coating film, which comprises a step of forming a TiO2 layer on a glass substrate by low temperature plasma CVD method using a film-forming material containing at least one member selected from an alkoxide type titanium material, an amide type titanium material and a halide type titanium material, at a plasma power density of at least 55 kW/m at a film-forming rate of from 15 to 200 nm·m/min.