Lead-Free Glass Composition for Semiconductor Junction Protection

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Solution Overview

Problem

Conventional glass materials used for semiconductor junction protection, such as lead silicate, pose environmental concerns and are likely to be prohibited, requiring a lead-free alternative that maintains high reliability and chemical resistance while matching silicon's linear expansion coefficient to prevent warping.

Innovation Solution

A glass composition made from fine glass particles containing SiO2, B2O3, Al2O3, and alkaline earth metal oxides, excluding Pb, As, Sb, Li, Na, K, and Zn, with specific mole percentage ranges and optionally including nickel oxide, to ensure proper baking temperature, chemical resistance, and linear expansion coefficient matching silicon.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lead silicate glass material is used for protecting semiconductor junction, then chemical resistance and reliability are improved, but environmental harm increases and the material is likely to be prohibited

Engineering Contradiction:

Improvechemical resistanceVSAvoidenvironmental harm

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters of the glass material by completely eliminating lead oxide and other harmful elements (As, Sb, Li, Na, K, Zn) while adjusting the proportions of SiO2, B2O3, Al2O3, and alkaline earth metal oxides to achieve the desired chemical resistance and physical properties without harmful substances

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite glass material system combining multiple oxide components (SiO2, B2O3, Al2O3, alkaline earth metal oxides) in specific proportions to achieve the required performance characteristics - chemical resistance, appropriate melting point, and linear expansion coefficient matching - while maintaining environmental compatibility

Inventive Principle:

Principle #40Composite materials

2Reliability

If glass material is used to protect semiconductor junction, then reliability is improved, but warping occurs due to mismatched linear expansion coefficient

Engineering Contradiction:

Improveprotection reliabilityVSAvoidwarping

Core Design Contradiction:

ReliabilityVSShape

Solution Approach 1:

The patent adjusts the chemical composition parameters of the glass to control its physical properties, specifically tuning the linear expansion coefficient to match that of silicon by optimizing the ratios of B2O3, Al2O3, and alkaline earth metal oxides in the glass composition

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If lead-free glass composition is used, then environmental compatibility is improved, but chemical resistance may deteriorate

Engineering Contradiction:

Improveenvironmental compatibilityVSAvoidchemical resistance

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent develops a composite glass system where multiple oxide components work synergistically - SiO2 provides the glass network structure and chemical inertness, B2O3 contributes to chemical resistance and lowers melting point, Al2O3 enhances durability, and alkaline earth metal oxides adjust physical properties while maintaining chemical stability, achieving both environmental compatibility and chemical resistance

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent optimizes the concentration parameters of each oxide component within specific ranges to achieve the desired balance between environmental compatibility and chemical resistance, adjusting the molecular ratio of network formers, modifiers, and stabilizers in the glass composition

Inventive Principle:

Principle #35Parameter changes

4Reliability

If glass layer is formed to cover pn junction, then device reliability is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvedevice reliabilityVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent adjusts the melting point and viscosity parameters of the glass composition to enable formation at appropriate temperatures and to ensure proper flow characteristics during the coating process, making the manufacturing process feasible while maintaining device reliability

Inventive Principle:

Principle #35Parameter changes

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 enables the manufacture of highly reliable semiconductor devices with improved chemical resistance and reduced warping, allowing for uniform layer formation and suppression of crystallization, even without lead, thus addressing environmental concerns and maintaining device performance.

Implementation Method 1

fine glass particles prepared from a material in a molten state obtained by melting a raw material which contains at least SiO2, B2O3, Al2O3 and oxide of alkaline earth metal

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

suppression of crystallization

Methodology Applied

Scientific EffectCrystallization suppression: Vitrification

Data Source

PatentUS9190365B2Glass composition for protecting semiconductor junction, method of manufacturing semiconductor device and semiconductor device

Publication Date: 2015.11.17 SHINDENGEN ELECTRIC MANUFACTURING CO LTD

AI summary

A glass composition for protecting a semiconductor junction is made of fine glass particles prepared from a material in a molten state obtained by melting a raw material which contains at least SiO2, B2O3, Al2O3 and oxide of alkaline earth metal and substantially contains none of Pb, As, Sb, Li, Na, K and Zn, and contains no filler.