Low-Alkali Glass Substrate Composition for Wafer Lamination
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Solution Overview
Problem
Current glass substrates for semiconductor devices face challenges in chemical resistance to acidic solutions, diffusion of alkali ions into silicon substrates during heat treatment, and residual strain issues due to thermal expansion differences, which affect the reliability and durability of laminated substrates in fan-out type wafer-level packaging.
Innovation Solution
A glass substrate composition with specific mole percentages of SiO2, Al2O3, B2O3, MgO, CaO, SrO, and BaO, having an alkali metal oxide content of 0-0.1%, and an average coefficient of thermal expansion of 56-90 × 10^-7/°C, is developed to enhance chemical resistance, reduce alkali ion diffusion, and minimize residual strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a glass substrate containing alkali metal oxide (5% or more) is used to achieve satisfactory chemical resistance to acidic solutions, then chemical resistance is improved, but alkali ion diffusion into silicon substrate occurs during heat treatment
Solution Approach 1:
The patent changes the chemical composition parameters of the glass substrate by strictly limiting alkali metal oxide content to 0-0.1% (down from conventional 5% or more) while adjusting other oxide ratios to achieve both low alkali ion diffusion and satisfactory chemical resistance through optimized composition rather than high alkali content
Solution Approach 2:
The patent creates a composite glass composition combining multiple oxides (SiO2, Al2O3, B2O3, MgO, CaO, SrO, BaO) in specific ratios to achieve a material that simultaneously provides chemical resistance, low alkali ion diffusion, and appropriate thermal expansion properties that conventional single-composition glasses cannot achieve
2Reliability
If a glass substrate with high alkali metal oxide content is used to improve chemical resistance, then chemical resistance is improved, but the glass substrate becomes prone to deformation or damage during heat treatment
Solution Approach 1:
The patent changes the alkali metal oxide content parameter from conventional high levels (5% or more) to extremely low levels (0-0.1%), and adjusts other compositional parameters to maintain chemical resistance through alternative mechanisms, thereby eliminating the trade-off between chemical resistance and structural integrity
Solution Approach 2:
The patent employs a composite glass composition with controlled ratios of multiple oxides that provides structural strength and chemical resistance through the synergistic effect of network formers and modifiers, replacing the conventional reliance on high alkali content for chemical resistance with a more balanced compositional approach that also enhances structural integrity
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 substrate exhibits satisfactory chemical resistance to acidic solutions, prevents alkali ion diffusion into silicon substrates, and reduces residual strain in laminated substrates, ensuring improved reliability and durability for fan-out type wafer-level packaging.
Implementation Method 1
A glass substrate according to one embodiment of the present invention has satisfactory chemical resistance to an acidic solution
Implementation Method 2
alkali ions is less apt to diffuse into a silicon substrate in a heat treatment step for sticking the glass substrate with the silicon substrate
Implementation Method 3
a residual strain that occurs to a laminated substrate in a heat treatment step is small
Data Source
AI summary
A glass substrate contains, as a glass matrix composition as represented by mole percentage based on oxides, SiO2: 58-75%, Al2O3: 4.5-16%, B2O3: 0-6%, MgO: 0-6%, CaO: 0-6%, SrO: 5-20%, BaO: 5-20%, and MgO+CaO+SrO+BaO:15-40%. The glass substrate has an alkali metal oxide content of 0-0.1% as represented by mole percentage based on oxides. The glass substrate has an average coefficient of thermal expansion α of 56-90 (×10−7/° C.) at 50° C.-350° C.