Vertical Power Component Passivation for Leakage Reduction
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Solution Overview
Problem
Existing peripheral structures of vertical semiconductor power components face issues with high breakdown voltage and leakage currents, particularly due to the instability of the interface between silicon oxide and silicon, leading to degradation in switching performance.
Innovation Solution
A passivation structure comprising alternating regions of different materials, such as silicon oxide and phosphosilicate glass or semi-insulating polysilicon, is applied to the peripheral region of the substrate, generating a local increase in majority carrier concentration to prevent parasitic channel formation and enhance breakdown voltage and reduce leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silicon oxide passivation layer is used on the peripheral region, then the interface stability is improved, but the breakdown voltage decreases and leakage currents increase due to parasitic channel formation
Solution Approach 1:
The patent applies different passivation materials with different properties to different regions of the peripheral substrate. Specifically, a first passivation material (such as silicon oxide) is applied to a first region, while a second passivation material (such as phosphosilicate glass or semi-insulating polysilicon) is applied to a second region. This local differentiation allows the first region to provide interface stability while the second region provides high breakdown voltage and low leakage currents by generating fixed charges that prevent parasitic channel formation.
Solution Approach 2:
The patent uses a composite passivation structure consisting of multiple passivation materials applied in different regions. The combination of silicon oxide (for interface stability) with phosphosilicate glass or semi-insulating polysilicon (for electrical isolation and fixed charge generation) creates a composite system that simultaneously achieves both interface stability and high breakdown voltage with minimal leakage currents.
2Ease of manufacture
If a uniform passivation material is applied to the entire peripheral region, then the manufacturing process is simplified, but the switching performance degrades due to parasitic channel formation
Solution Approach 1:
The patent divides the peripheral region into multiple zones with different passivation materials. The first region receives a passivation material optimized for interface stability, while the second region receives a passivation material optimized for electrical isolation. This local quality differentiation maintains switching performance by preventing parasitic channel formation in the second region, while the overall process remains manufacturable using standard semiconductor fabrication techniques.
3Object-affected harmful factors
If the passivation structure uses only insulating materials, then the electrical isolation is improved, but the majority carrier concentration at the surface remains low leading to parasitic channel formation
Solution Approach 1:
The second passivation material acts as an intermediary that provides both electrical isolation and fixed charge generation. Materials such as phosphosilicate glass and semi-insulating polysilicon contain fixed charges that are transferred to the silicon substrate interface, creating a depletion layer that prevents parasitic channel formation while maintaining electrical isolation. This intermediary layer resolves the contradiction between isolation and carrier concentration.
Solution Approach 2:
The patent changes the electrical parameters of the passivation structure by introducing materials with fixed charge characteristics. The fixed charge density in the second passivation material is specifically engineered to create sufficient depletion width at the silicon interface to prevent parasitic channel formation, while the overall passivation structure maintains its electrical isolation 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 proposed solution effectively improves the breakdown voltage and limits leakage currents while maintaining or improving switching performance by creating a localized accumulation of carriers that inhibits parasitic channel formation, thereby enhancing the reliability and efficiency of the vertical power component.
Implementation Method 1
the second region being capable of generating, in a surface region of the substrate in contact with said second region, a local increase of the concentration of majority carriers in the substrate
Data Source
AI summary
A vertical power component includes a doped silicon substrate of a first conductivity type. A local well of a second conductivity type extends from an upper surface of the substrate. A passivation structure coats a peripheral region of the upper surface side of the substrate surrounding the well. This passivation structure includes, on top of and in contact with the peripheral substrate region, a first region made of a first passivation material and a second region made of a second passivation material. The second region generates, in a surface region of the substrate in contact with said second region, a local increase of the concentration of majority carriers in the substrate.