Segmented Schottky Diode Guard Rings for High-Voltage SOI
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Solution Overview
Problem
Schottky diodes on silicon-on-insulator (SOI) substrates operating above 60 volts face challenges due to bias effects from the handle wafer, which affect breakdown voltage and device performance.
Innovation Solution
A semiconductor device with a Schottky diode on an SOI substrate is designed, featuring a guard ring and a drift region of opposite conductivity types, along with a metal-containing layer forming a barrier at the Schottky barrier region interface, to mitigate bias effects and enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the lateral dimensions are increased to extend breakdown voltage on SOI substrates, then the breakdown voltage is improved, but the device area increases
Solution Approach 1:
The guard ring is divided into multiple discrete segments rather than a continuous structure. These segmented guard rings are distributed around the Schottky barrier region, providing voltage control and breakdown extension functionality while reducing the total area occupied compared to a continuous guard ring of equivalent effectiveness.
2Adaptability or versatility
If Schottky diodes operate above 60 volts on SOI substrates, then the operating voltage range is improved, but bias effects from the handle wafer worsen performance
Solution Approach 1:
The segmented guard rings act as intermediary structures between the Schottky barrier region and the handle wafer. These guard rings control the electric field distribution and potential gradients in the drift region, mediating the interaction between the high-voltage operation and the handle wafer bias effects, thereby enabling stable operation above 60 volts.
Solution Approach 2:
The patent modifies the electrical parameters in the drift region by introducing segmented guard rings with specific doping types and concentrations. This changes the potential distribution and electric field characteristics, allowing the device to operate at higher voltages while compensating for handle wafer bias effects through controlled parameter variations.
3Strength
If a continuous guard ring structure is used, then the breakdown voltage control is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The guard ring is divided into multiple discrete segments rather than a continuous structure. These segmented guard rings are distributed around the Schottky barrier region, providing voltage control and breakdown extension functionality while reducing the total area occupied compared to a continuous guard ring of equivalent effectiveness.
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 solution effectively extends breakdown voltage and improves on-state current and leakage current characteristics of Schottky diodes on SOI substrates, enabling operation at higher voltages with reduced bias effects.
Implementation Method 1
A Schottky barrier region having the second conductivity type in the semiconductor layer, contacting the drift region, and a metal-containing layer contacting the Schottky barrier region. A barrier of the Schottky diode is formed at an interface between the Schottky barrier region and the metal-containing layer.
Implementation Method 2
The guard ring includes a first guard ring segment contacting the Schottky barrier region on a first lateral side of the barrier region, and a second guard ring segment contacting the Schottky barrier region on a second, opposite, lateral side of the Schottky barrier region.
Data Source
AI summary
A semiconductor device includes a Schottky diode on a silicon-on-insulator (SOI) substrate. The Schottky diode includes a guard ring with a first guard ring segment contacting a barrier region on a first lateral side of the barrier region, and a second guard ring segment contacting the barrier region on a second, opposite, lateral side of the barrier region. The first and second guard ring segments extend deeper in the semiconductor layer than the barrier region. The Schottky diode further includes a drift region contacting the barrier region, and may include a buried layer having the same conductivity type as the barrier region, extending at least partway under the drift region. The barrier region is isolated from the substrate dielectric layer of the SOI substrate by an isolation region having the same conductivity type as the guard ring. A metal containing layer is formed on the barrier region.