Galvanic Isolation Dielectric Sidewall Sealing Against Moisture
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Solution Overview
Problem
Dielectric materials in galvanic isolation devices are prone to degradation due to moisture ingress, leading to potential cracking and electrical isolation degradation, especially in high voltage applications.
Innovation Solution
Incorporating a nitrogen-containing plasma treatment to form a silicon oxynitride (SiOxNy) layer on the dielectric sidewalls, creating a moisture barrier and hermetic seal to prevent moisture ingress and enhance the resistance to cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dielectric material is used to isolate elements in isolators, then electrical isolation is achieved, but the dielectric material is subject to degradation due to moisture ingress
Solution Approach 1:
A silicon oxynitride (SiOxNy) layer is introduced as an intermediary moisture barrier between the dielectric material and the external environment. This intermediate layer prevents moisture from reaching and degrading the dielectric material, thereby protecting the electrical isolation function while allowing the dielectric to maintain its isolation properties.
Solution Approach 2:
The patent employs a composite structure consisting of multiple dielectric layers including silicon dioxide and silicon oxynitride. This composite material approach combines the electrical isolation properties of silicon dioxide with the moisture barrier properties of silicon oxynitride, achieving both electrical isolation and moisture protection simultaneously.
2Reliability
If dielectric material is used in high voltage applications, then galvanic isolation is achieved, but dielectric breakdown is a key concern
Solution Approach 1:
The silicon oxynitride layer is applied beforehand to protect the dielectric material from moisture-induced degradation. This preventive measure cushiones the dielectric against environmental factors that would otherwise weaken it over time, maintaining its dielectric strength and preventing breakdown in high voltage applications.
Solution Approach 2:
The composite dielectric structure combines multiple materials with complementary properties. The silicon oxynitride layer provides both moisture barrier functionality and additional dielectric strength, while the silicon dioxide layers provide electrical isolation. This composite approach enhances overall dielectric strength to withstand high voltage conditions.
3Strength
If alternating layers of high stress and low stress silicon dioxide are used, then resistance to cracking is improved, but device complexity increases
Solution Approach 1:
The dielectric layer is segmented into alternating layers of high stress and low stress silicon dioxide. This segmentation allows each sub-layer to have optimized stress characteristics, with high stress layers providing crack resistance and low stress layers accommodating thermal expansion differences. The segmented structure prevents through-cracks while managing mechanical stress distribution.
Solution Approach 2:
The patent varies the stress parameter of the silicon dioxide layers by creating alternating high stress and low stress regions. This parameter change approach allows optimization of crack resistance through stress distribution while maintaining compatibility with underlying substrates. The stress parameter is controlled during deposition to achieve the desired mechanical properties.
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 SiOxNy layer effectively prevents moisture ingress, thereby stabilizing dielectric stress and improving the integrity of galvanic isolation devices, particularly in high voltage environments.
Implementation Method 1
The plateau contains a sidewall moisture barrier of silicon SiOxNy which is formed by an ammonia plasma treatment or pretreatment with another nitrogen containing precursor
Implementation Method 2
The plateau contains a moisture barrier over the plateau of silicon nitride, silicon oxynitride herein referred to as SiOxNy
Implementation Method 3
creating a moisture barrier and hermetic seal to prevent moisture ingress and enhance the resistance to cracking
Implementation Method 4
Alternating layers of high stress silicon dioxide and low stress silicon dioxide may provide a means of reinforcement of the plateau which improves resistance to cracking of the plateau
Data Source
AI summary
A microelectronic device including an isolation device with a stabilized dielectric. The isolation device includes a lower isolation element, an upper isolation element, and an inorganic dielectric plateau between the lower isolation element and the upper isolation element. The dielectric sidewall of the inorganic dielectric plateau is stabilized in a nitrogen containing plasma which forms a SiOxNy surface on the dielectric sidewall of the inorganic dielectric plateau. The SiOxNy surface on the dielectric sidewall of the inorganic dielectric plateau reduces ingress of moisture into the dielectric stack of the inorganic dielectric plateau.