Alkali-Free Glass Substrate Composition for Display Etching
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Solution Overview
Problem
Conventional glass substrates for displays have a low etching rate in HF-based chemicals, leading to impaired etching uniformity and increased insoluble fine particles, making it difficult to achieve high etching efficiency, strain point, and devitrification resistance simultaneously.
Innovation Solution
A glass substrate composition of 65-75% SiO2, 11-15% Al2O3, 0-5% B2O3, 0-5% MgO, 0-10% CaO, 0-6% BaO, and 0.01-5% P2O5, with a molar ratio (MgO+CaO+SrO+BaO)/Al2O3 from 0.7 to 1.5, optimized to enhance etching rate and strain point while maintaining devitrification resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the concentration of HF in the chemical is increased to increase the etching rate, then the etching rate is improved, but insoluble fine particles are increased and etching uniformity is impaired
Solution Approach 1:
The patent changes the chemical composition parameters of the glass substrate by controlling the content of B2O3 (0.1-5.0 mol%), Al2O3 (10.0-20.0 mol%), and other oxides to achieve optimal etching performance. This parameter optimization allows the glass to have high etching rate while maintaining etching uniformity and reducing fine particle generation in HF-based chemicals.
2Reliability
If the glass substrate contains alkaline component at high content, then the glass has good chemical resistance, but alkali ion diffuses into semiconductor film during heat treatment causing degradation
Solution Approach 1:
The patent optimizes the glass composition by controlling the content of alkaline components (Li2O, Na2O, K2O) within specific ranges (0.01-2.0 mol% each) and establishes a relationship between alkaline component content and SiO2 content (0.5≤[SiO2]-2×([Li2O]+[Na2O]+[K2O])) to prevent alkali ion diffusion into semiconductor films during heat treatment while maintaining chemical resistance.
3Stability of the object's composition
If the glass substrate undergoes thermal shrinkage during heat treatment, then the glass has low thermal stability, but pattern shift occurs on large-size glass substrate
Solution Approach 1:
The patent optimizes the glass composition by controlling B2O3 (0.1-5.0 mol%), Al2O3 (10.0-20.0 mol%), and other oxides to achieve optimal thermal stability. This parameter optimization allows the glass to have low thermal shrinkage during heat treatment while maintaining dimensional stability and preventing pattern shift on large-size substrates.
4Reliability
If conventional glass composition is used, then the glass has good devitrification resistance, but etching rate is low making thinning process inefficient
Solution Approach 1:
The patent optimizes the glass composition by controlling B2O3 (0.1-5.0 mol%), Al2O3 (10.0-20.0 mol%), SiO2 (60.0-75.0 mol%), and other oxides to achieve both high etching rate and excellent devitrification resistance. This parameter optimization allows the glass to be efficiently thinned during manufacturing while maintaining structural stability.
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 optimized glass substrate achieves a high etching rate, high strain point, and excellent devitrification resistance, reducing production costs and thermal shrinkage, and improving the efficiency of display panel thinning.
Implementation Method 1
chemical etching for a glass substrate is employed in order to reduce the thickness of the display. This method involves immersing a display panel obtained by bonding two glass substrates in a hydrofluoric acid (HF)-based chemical to reduce the thicknesses of the glass substrates.
Implementation Method 2
the glass substrate is subjected to heat treatment at several hundred degrees C. in steps of film formation, annealing, and the like
Implementation Method 3
the glass substrate is subjected to heat treatment at several hundred degrees C. in steps of film formation, annealing, and the like, and hence a pattern shift or the like is liable to occur when the glass substrate undergoes thermal shrinkage during the heat treatment.
Implementation Method 4
an alkali ion is diffused during heat treatment into a semiconductor substance having been formed into a film and causes degradation in the characteristics of the film when the glass substrate contains the alkaline component at a high content.
Implementation Method 5
To have a thermal expansion coefficient close to that of a film member to be formed on the glass substrate (for example, of a-Si or p-Si), for example, have a thermal expansion coefficient of from 30×10−7/° C. to 45×10−7/° C.
Data Source
AI summary
A technical object of the present invention is to devise an alkali-free glass that has a high etching rate in a HF-based chemical and a high strain point while having excellent productivity (particularly, devitrification resistance), to thereby reduce the production cost of a glass substrate, and then increase thinning efficiency and reduce the thermal shrinkage of the glass substrate in a production process of a display panel. In order to achieve the above-mentioned object, a glass substrate of the present invention includes as a glass composition, in terms of mol %, 65% to 75% of SiO2, 11% to 15% of Al2O3, 0% to 5% of B2O3, 0% to 5% of MgO, 0% to 10% of CaO, 0% to 5% of SrO, 0% to 6% of BaO, and 0.01% to 5% of P2O5, and has a molar ratio (MgO+CaO+SrO+BaO)/Al2O3 of from 0.7 to 1.5.