Schottky Diode Guard Ring Voltage Distribution
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Solution Overview
Problem
Conventional trench Schottky diodes face limitations in reverse bias and leakage current, leading to early breakdown due to accumulation of surface charges at the termination area, which the existing guard ring structures fail to adequately address.
Innovation Solution
A Schottky diode with multiple guard ring structures, including first, second, and third ion implantation guard rings with varying widths and spacings, and a separation portion in the metal layer to distribute voltage levels stepwise, preventing surface charge accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single guard ring structure is used in the termination area, then the voltage level can be partially buffered, but surface charges still accumulate at the termination area rim leading to early breakdown
Solution Approach 1:
The single guard ring structure is divided into multiple guard rings (first, second, and third guard rings) with different widths and spacing. This segmentation allows for progressive voltage buffering across multiple zones, effectively distributing the electric field and preventing charge accumulation at any single location, thereby resolving the contradiction between reliability improvement and structural complexity.
Solution Approach 2:
Each guard ring is designed with different local properties (widths of 5μm, 3μm, and 1μm respectively) to create localized voltage buffering zones. The varying widths and spacing create a gradient effect that progressively manages the electric field distribution, allowing each region to address specific local charge accumulation issues while collectively improving overall reverse bias performance.
2Strength
If metal layers are extended into the termination area to increase reverse bias, then reverse breakdown voltage increases, but surface charges accumulate on the epitaxial layer causing early breakdown
Solution Approach 1:
Multiple guard rings are introduced as intermediary structures between the metal layers and the epitaxial layer termination area. These guard rings act as intermediate zones that progressively buffer the voltage stress, preventing direct charge accumulation on the epitaxial layer while still allowing the metal layers to extend into the termination area for increased reverse breakdown voltage.
3Ease of manufacture
If the guard ring structure is simplified to reduce device complexity, then manufacturing becomes easier, but the ability to buffer voltage levels is insufficient leading to charge accumulation
Solution Approach 1:
The guard ring structure is segmented into three distinct rings with progressively decreasing widths (5μm, 3μm, 1μm) and specific spacing (3μm between first and second, 1μm between second and third). This segmentation provides enhanced voltage buffering capability while maintaining a relatively simple fabrication process that can be integrated into existing manufacturing workflows.
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 multiple guard ring structure effectively distributes voltage levels, preventing early breakdown and maintaining stable reverse bias performance comparable to conventional trench Schottky diodes.
Implementation Method 1
The epitaxial layer includes a termination trench structure, a first ion implantation guard ring, a second ion implantation guard ring and a third ion implantation guard ring
Data Source
AI summary
A Schottky diode with multiple guard ring structures includes a semiconductor base layer, a back metal layer, an epitaxial layer, a dielectric layer, a first metal layer, a passivation layer and a second metal layer. The epitaxial layer on the semiconductor base layer includes a terminal trench structure, a first ion implantation guard ring, a second ion implantation guard ring and a third ion implantation guard ring. The dielectric layer is on the epitaxial layer in a termination area. The first metal layer is on the terminal trench structure and the dielectric layer. The passivation layer is on the first metal layer and the dielectric layer. The second metal layer is on the first metal layer and the passivation layer. Widths of the first, second and third ion implantation guard rings decrease in order, so that the voltage can be distributed step by step.