Lead-Free Glass Passivation for Semiconductor Junctions
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Solution Overview
Problem
Conventional methods for manufacturing semiconductor devices using lead-free glass materials face challenges in achieving high breakdown strength, preventing warping, withstanding chemicals, maintaining low reverse direction leak current, and avoiding bubble generation during the glass layer formation process without adding defoaming agents.
Innovation Solution
A method involving the formation of a semiconductor device with a glass layer composed of fine glass particles made from a molten mixture containing SiO2, Al2O3, B2O3, ZnO, and alkaline earth metals, baked at a temperature of 900°C or below, with an insulation layer interposed between the semiconductor base body and the glass layer to enhance wettability and insulation properties, and to suppress bubble generation and reverse direction leak current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lead-free glass material is used for forming glass layer, then environmental compatibility is improved, but breakdown strength and insulation properties deteriorate
Solution Approach 1:
The patent uses a composite glass composition containing multiple metal oxides (SiO2, B2O3, Al2O3, ZnO, MgO, CaO, BaO) in specific proportions to achieve both environmental compatibility and high breakdown strength. This composite approach allows optimization of electrical properties while maintaining lead-free composition.
Solution Approach 2:
The patent optimizes the chemical composition parameters of the glass layer by controlling the ratios of various metal oxides and adjusting the baking temperature (900°C or below) to achieve the desired breakdown strength and insulation properties without using lead.
2Reliability
If glass layer is formed by baking glass composition, then passivation is achieved, but bubble generation occurs at boundary surface
Solution Approach 1:
The patent introduces an insulation layer as an intermediary between the semiconductor base body and the glass layer. This intermediate layer improves wettability during the glass layer formation process, preventing bubble generation at the boundary surface while maintaining effective passivation.
Solution Approach 2:
The insulation layer is formed in advance before applying the glass composition. This preliminary action prepares the surface with appropriate wettability characteristics, ensuring that when the glass layer is subsequently formed and baked, bubbles do not generate at the interface.
3Reliability
If glass layer is formed to cover pn junction exposure portion, then breakdown strength is improved, but reverse direction leak current increases
Solution Approach 1:
The patent optimizes the glass composition parameters, specifically controlling the content of metal oxides and excluding certain elements (Pb, As, Sb, Li, Na, K) to achieve low reverse direction leak current while maintaining high breakdown strength. The baking temperature is also controlled at 900°C or below to prevent excessive current.
4Ease of manufacture
If conventional glass composition is used, then manufacturing process is simple, but warping occurs during baking
Solution Approach 1:
The patent adjusts the chemical composition parameters of the glass layer, specifically incorporating certain metal oxides in controlled proportions and excluding others, to match the thermal expansion characteristics with the semiconductor substrate. This prevents warping during baking while maintaining process simplicity.
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 method enables the production of semiconductor devices with high breakdown strength, stable low reverse direction leak current, and reduced bubble formation, while maintaining excellent insulation properties and resistance to high-temperature reverse bias, without the need for lead or excessive defoaming agents.
Implementation Method 1
the layer made of glass composition for protecting a semiconductor junction is baked, wherein the glass composition for protecting a semiconductor junction is a glass composition for protecting a semiconductor junction which is made of fine glass particles prepared from a material in a molten state which is obtained by melting a raw material
Implementation Method 2
a layer made of glass composition for protecting a semiconductor junction is formed on the insulation layer
Data Source
AI summary
Provided is a method of manufacturing a semiconductor device which includes, in the following order: a first step of preparing a semiconductor element which includes a pn junction exposure portion; a second step of forming an insulation layer such that the insulation layer covers the pn junction exposure portion; and a third step of forming a glass layer on the insulation layer where a layer made of glass composition for protecting a semiconductor junction is formed on the insulation layer and, thereafter, the layer made of glass composition for protecting a semiconductor junction is baked.