Non-alkali Glass Composition for Low Thermal Shrinkage
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Solution Overview
Problem
Conventional non-alkali glasses for displays and photomasks face challenges in achieving a low thermal shrinkage rate, high productivity, and resistance to buffered hydrofluoric acid (BHF) while maintaining a balance between alkali metal oxide content and B2O3 levels to prevent defects and variations in thermal shrinkage rates.
Innovation Solution
A non-alkali glass composition with a strain point of 680° C. or higher, containing SiO2 (54-66%), Al2O3 (10-27%), B2O3 (0.2-5.5%), and specific ratios of MgO, CaO, SrO, and BaO, with Na2O content limited to 600 mass ppm or less, to optimize thermal expansion coefficients and meltability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If B2O3 content is increased to improve BHF resistance, then BHF resistance is improved, but strain point is reduced
Solution Approach 1:
The patent optimizes the B2O3 content parameter within a specific range (0.2-5.5 mass%) to achieve the desired balance between BHF resistance and strain point. By precisely controlling this compositional parameter, the glass formulation attains sufficient chemical durability against BHF while maintaining an adequate strain point for float processing.
Solution Approach 2:
The patent creates a composite glass system combining multiple oxide components (SiO2, Al2O3, B2O3, and various metal oxides) in specific proportions. This composite formulation synergistically achieves BHF resistance through B2O3 while the overall composition maintains appropriate strain point characteristics, resolving the contradiction between these two properties.
2Manufacturing precision
If alkali metal oxide content is reduced to improve thermal shrinkage rate, then thermal shrinkage rate is improved, but meltability is worsened
Solution Approach 1:
The patent严格控制 alkali metal oxide content to 600 mass ppm or less to achieve low thermal shrinkage rate suitable for high-definition displays. Simultaneously, it optimizes other compositional parameters including B2O3 content (0.2-5.5 mass%) and metal oxide ratios to maintain adequate meltability and float processing characteristics despite the low alkali content.
Solution Approach 2:
The patent applies different compositional strategies to different functional requirements: very low alkali metal oxide content (≤600 ppm) for thermal stability and low shrinkage, while maintaining higher B2O3 content (0.2-5.5 mass%) and optimized metal oxide ratios specifically for improving meltability and float processing, thereby resolving the contradiction between thermal performance and manufacturability.
3Temperature
If B2O3 content is reduced to increase strain point, then strain point is increased, but BHF resistance is worsened
Solution Approach 1:
The patent establishes an optimal B2O3 content range (0.2-5.5 mass%) that simultaneously provides sufficient BHF resistance and maintains adequate strain point for float processing. This precise parameter control resolves the contradiction by finding the compositional sweet spot where both requirements are satisfied.
Solution Approach 2:
The B2O3 component serves multiple functions in the glass formulation: it provides BHF resistance through its chemical structure, contributes to meltability, and when controlled within the specified range, maintains adequate strain point. This multi-functionality of B2O3 allows the patent to resolve the contradiction between BHF resistance and strain point by optimizing its concentration.
4Ease of manufacture
If alkali metal oxide content is increased to improve meltability, then meltability is improved, but thermal shrinkage rate increases
Solution Approach 1:
The patent optimizes alkali metal oxide content to 600 mass ppm or less to achieve low thermal shrinkage rate, while compensating for reduced meltability through optimized B2O3 content (0.2-5.5 mass%) and metal oxide ratios. This parameter optimization resolves the contradiction by finding the balance point where thermal performance and manufacturability are both satisfied.
Solution Approach 2:
The patent uses B2O3 and metal oxides as intermediary components to mediate between the conflicting requirements of low alkali content (for low shrinkage) and adequate meltability. These intermediary substances provide the necessary melting assistance and float processing characteristics without requiring high alkali metal oxide content, thereby resolving the contradiction.
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 glass exhibits a reduced thermal shrinkage rate, improved BHF resistance, and reduced defect rates in panel manufacturing, suitable for high-definition displays and photomasks, while maintaining a balance between alkali metal oxide content and B2O3 levels to prevent excessive thermal shrinkage.
Implementation Method 1
having an average thermal expansion coefficient of from 30×10−7/° C. to 45×10−7/° C. at from 50° C. to 350° C.
Implementation Method 2
Having sufficient chemical durability against various chemicals used in semiconductor formation; in particular, having durability against buffered hydrofluoric acid (BHF: mixed liquid of hydrofluoric acid and ammonium fluoride) for etching SiOx or SiNx
Data Source
AI summary
Provided is a non-alkali glass having a strain point of 680° C. or higher, having an average thermal expansion coefficient of from 30×10−7/° C. to 45×10−7/° C. at from 50° C. to 350° C., containing, indicated by mass % on the basis of oxides: SiO2: 54% to 66%, Al2O3: 10% to 27%, B2O3: 0.2% to 5.5%, MgO: 0% to 10%, CaO: 0% to 15%, SrO: 0% to 15%, BaO: 0% to 15%, and MgO+CaO+SrO+BaO: 8% to 25%, containing 600 mass ppm or less of Na2O, and satisfying a mass ratio (Na2O/B2O3) between Na2O and B2O3 being from 0.001 to 0.3.