Glass Substrate Composition for Silicon-Matched Thermal Expansion
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Solution Overview
Problem
The production of ultrahigh-definition display devices faces challenges due to issues such as warping of alkali-free glass substrates caused by thermal expansion differences with silicon wafers, pattern deviations due to thermal shrinkage, and clouding of the glass substrate during chemical treatments.
Innovation Solution
A glass substrate with a compaction of 0.1 to 100 ppm and a controlled coefficient of thermal expansion, ensuring that the differences between the glass substrate and single-crystal silicon are minimized, thereby reducing residual strains and thermal shrinkage effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alkali-free glass substrate is used for ultrahigh-definition display manufacturing, then chemical resistance and purity are improved, but warping occurs due to thermal expansion difference with silicon wafer
Solution Approach 1:
The patent modifies the thermal expansion characteristics of the glass substrate by controlling its composition (specifically SiO2 content at 60-75 mol%, B2O3 at 5-15 mol%, and other oxides) to achieve an average coefficient of thermal expansion between 2.5-4.5 ppm/°C. This parameter adjustment allows the glass to better match the thermal expansion of single-crystal silicon during the lamination process, reducing warping while maintaining chemical resistance.
2Manufacturing precision
If alkali-free glass substrate is used, then pattern deviation due to thermal shrinkage is reduced, but manufacturing complexity increases due to precise composition control requirements
Solution Approach 1:
The patent establishes specific compositional ranges for the glass substrate (SiO2: 60-75 mol%, B2O3: 5-15 mol%, Al2O3: 3-10 mol%, and other oxides within defined ranges) that inherently provide the desired low thermal shrinkage characteristics. By defining these parameter ranges, the patent simplifies the manufacturing process while ensuring consistent pattern accuracy across production batches.
3Reliability
If alkali-free glass substrate is used, then clouding during chemical treatment is suppressed, but coefficient of thermal expansion mismatch with silicon wafer causes warping
Solution Approach 1:
The patent optimizes the glass composition by eliminating alkali metals and carefully controlling the content of network formers (SiO2, B2O3) and network modifiers (Al2O3, MgO, CaO, SrO, BaO) to achieve both chemical treatment stability and thermal expansion compatibility. The specific compositional ranges ensure resistance to clouding during chemical treatments while matching the thermal expansion of silicon wafers.
4Shape
If glass substrate with low thermal expansion is used, then warping is reduced, but manufacturing precision requirements increase for maintaining pattern accuracy
Solution Approach 1:
The patent achieves a balance between warping control and pattern accuracy by optimizing the glass composition to have a specific thermal expansion range (2.5-4.5 ppm/°C) that closely matches single-crystal silicon. This parameter optimization reduces the differential thermal expansion between layers, thereby minimizing both warping and pattern deviation during the manufacturing process.
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 proposed glass substrate effectively suppresses warping, pattern deviations, and clouding, making it suitable for manufacturing small-size, high-definition display devices with improved reliability and performance.
Implementation Method 1
an absolute value |Δα50/100| of a difference between an average coefficient of thermal expansion α50/100 of the glass substrate and an average coefficient of thermal expansion of single-crystal silicon at 50° C. to 100° C.
Implementation Method 2
a pattern deviates due to thermal shrinkage of the glass substrate during the heat treatment
Data Source
AI summary
A glass substrate has a compaction of 0.1 to 100 ppm. An absolute value |Δα50/100| of a difference between an average coefficient of thermal expansion α50/100 of the glass substrate and an average coefficient of thermal expansion of single-crystal silicon at 50° C. to 100° C., an absolute value |Δα100/200| of a difference between an average coefficient of thermal expansion α100/200 of the glass substrate and an average coefficient of thermal expansion of the single-crystal silicon at 100° C. to 200° C., and an absolute value |Δα200/300| of a difference between an average coefficient of thermal expansion α200/300 of the glass substrate and an average coefficient of thermal expansion of the single-crystal silicon at 200° C. to 300° C. are 0.16 ppm/° C. or less.