Power Device Terminal Structure for Moisture Blocking and Field Grading
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Solution Overview
Problem
Existing power semiconductor devices face challenges in maintaining reliability due to moisture ingress, which leads to increased leakage current and breakdown, especially under high humidity, high temperature, and high voltage reverse bias conditions.
Innovation Solution
A terminal structure for power semiconductor devices is designed, comprising a phosphorous-doped silicon oxide layer, a silicon nitride layer, a silicon-rich silicon nitride semi-insulating layer, an undoped silicon dioxide layer, and an organic medium layer, arranged to prevent moisture invasion and evenly distribute the electric field, thereby enhancing breakdown resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional terminal structure with silicon nitride layer is used, then the device provides basic passivation and ion barrier protection, but moisture ingress occurs under high humidity and temperature conditions leading to increased leakage current and breakdown
Solution Approach 1:
The patent employs a composite passivation structure consisting of multiple layers including silicon nitride, silicon oxide, and organic medium layers. This multi-material composite approach provides superior moisture barrier protection compared to single-material structures, preventing moisture ingress that leads to leakage current and breakdown while maintaining device reliability under harsh conditions.
Solution Approach 2:
The terminal structure implements a nested multi-layer configuration where different passivation layers are stacked sequentially. The silicon nitride layer, silicon oxide layer, and organic medium layer are arranged in nested fashion, with each layer providing complementary protection against moisture infiltration, thereby enhancing overall device reliability.
2Object-affected harmful factors
If the silicon nitride layer is used as passivation layer, then it provides good ion barrier protection, but it reacts with infiltrating moisture at high voltage causing oxidation that reduces density and increases leakage current
Solution Approach 1:
The patent introduces an intermediary organic medium layer in contact with the silicon nitride layer. This intermediary layer acts as a protective barrier that prevents direct reaction between the silicon nitride and infiltrating moisture, thereby preventing oxidation of the silicon nitride layer that would otherwise reduce its density and increase leakage current while maintaining ion contamination protection.
3Device complexity
If conventional terminal design is used, then the structure is simple, but electric field concentrates at the device terminal causing breakdown at low voltages
Solution Approach 1:
The patent applies local quality modification by creating a graded semi-insulating layer with varying conductivity across the terminal structure. This non-uniform conductivity distribution is specifically designed at the terminal region to distribute the electric field evenly, preventing concentration at critical points and thereby increasing breakdown voltage without significantly increasing overall device complexity.
4Ease of operation
If moisture infiltration is allowed to proceed, then the device operates initially, but accumulated moisture causes condensation that modifies material characteristics and leads to device failure
Solution Approach 1:
The patent implements preliminary anti-action by providing a multi-layer passivation structure that proactively prevents moisture infiltration before it can cause harmful effects. The composite barrier structure blocks moisture at the terminal interface, preventing the accumulation and condensation that would otherwise modify material characteristics and lead to device failure, thereby extending device lifetime while maintaining operation.
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 proposed terminal structure effectively reduces leakage current, improves device reliability, simplifies manufacturing processes, and achieves cost savings by preventing moisture ingress and optimizing electric field distribution.
Implementation Method 1
diffusion barriers like silicon nitride and phosphorus or boron-doped SiO2 layers are employed to enhance device protection against ion contamination
Implementation Method 2
the silicon nitride layer reacts with the infiltrating moisture at high voltage, and is oxidized. One the one hand, the oxidation process diminishes the density of the silicon nitride
Implementation Method 3
The semi-insulating layer can be adjusted in conductivity to achieve a continuous reduction in the surface potential of the power semiconductor device, thereby lowering the risk of terminal breakdown under high voltages
Data Source
AI summary
A terminal structure with optimized reliability for a power semiconductor device, a preparation method therefor, application thereof, a power device and a preparation method therefor are provided. The terminal structure includes a phosphorus-doped silicon oxide layer, a silicon nitride layer, a silicon-rich silicon nitride semi-insulating layer, an undoped silicon dioxide layer, and an organic medium layer. The silicon-rich silicon nitride semi-insulating layer is of an alternating superposition structure of a silicon-rich silicon nitride layer and an ultra-thin silicon nitride barrier layer. The terminal structure effectively prevents external moisture from invading the power device, which improves the robustness of the power device under a moisture condition. The multi-layer silicon-rich silicon nitride is used as a semi-insulating layer, which makes an electric field on a surface of the power device evenly distributed in gradient, prevents the electric field from being gathered at a device terminal.