Lead-Free Glass Composition for Semiconductor Junction Passivation
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Solution Overview
Problem
Conventional glass materials used for semiconductor junction passivation containing lead silicate face environmental concerns and generate bubbles during processing, leading to deteriorated reverse breakdown voltage characteristics when lead-free alternatives are used.
Innovation Solution
A glass composition comprising SiO2, Al2O3, and at least one metal oxide from nickel oxide, copper oxide, or manganese oxide, with specific mole percentage ranges, is used to form a glass layer that covers the semiconductor junction, preventing bubble formation and maintaining high breakdown voltage performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lead-free glass material is used for passivation, then environmental friendliness is improved, but bubbles are generated during processing leading to deteriorated reverse breakdown voltage characteristics
Solution Approach 1:
The patent changes the chemical composition parameters of the glass material by specifying precise mole percentage ranges of SiO2 (65-75%), Al2O3 (15-25%), and metal oxides (NiO, CuO, or MnO) (0.1-5%), while eliminating lead content. This parameter optimization prevents bubble formation during processing while maintaining passivation effectiveness and high breakdown voltage characteristics.
Solution Approach 2:
The patent creates a composite glass material system combining multiple metal oxides (nickel oxide, copper oxide, or manganese oxide) with silica and alumina. This composite composition achieves both environmental friendliness by eliminating lead and functional performance by preventing bubble generation during electrophoresis processing while maintaining reliable reverse breakdown voltage characteristics.
2Ease of manufacture
If conventional glass composition is used, then manufacturing process is simple, but toxic components (lead, phosphorus, arsenic, antimony, lithium, sodium, potassium) are present
Solution Approach 1:
The patent extracts and eliminates all toxic components (Pb, P, As, Sb, Li, Na, K) from the glass composition while retaining the essential structural components (SiO2, Al2O3) and adding functional metal oxides (NiO, CuO, MnO). This extraction maintains manufacturing simplicity by using a comparable number of components without lead while achieving environmental friendliness.
3Area of stationary object
If glass layer is formed by electrophoresis, then coverage of pn junction is achieved, but bubbles are generated at the boundary surface during baking
Solution Approach 1:
The patent changes the chemical composition parameters of the glass material to include specific ratios of SiO2 (65-75%), Al2O3 (15-25%), and metal oxides (0.1-5%), which modifies the material's surface tension and wetting properties during electrophoresis and baking. This parameter optimization ensures complete pn junction coverage while preventing bubble formation at the glass-substrate boundary interface.
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 composition effectively suppresses bubble generation and maintains high breakdown voltage characteristics in semiconductor devices, similar to those using lead-containing glass materials, while being environmentally friendly by eliminating lead and other toxic components.
Implementation Method 1
A glass composition for protecting a semiconductor junction contains at least SiO2, Al2O3, MO, and 'at least one metal oxide selected from a group consisting of nickel oxide, copper oxide and manganese oxide', and substantially contains none of Pb, P, As, Sb, Li, Na and K
Implementation Method 2
oxide films 916, 918 are formed by thermal oxidation on a surface of the p+ type diffusion layer 912 and a surface of the n+ type diffusion layer 914 respectively
Implementation Method 3
a layer made of glass composition for protecting a semiconductor junction is formed on an inner surface of the trench 920 and a surface of the semiconductor substrate in the vicinity of the trench 920 by electrophoresis
Data Source
AI summary
A glass composition for protecting a semiconductor junction contains at least SiO2, Al2O3, MO, and nickel oxide, and substantially contains none of Pb, P, As, Sb, Li, Na and K (M in MO indicates one of alkali earth metals).