Segmented Schottky Diode Structure for SOI Bias Isolation
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Solution Overview
Problem
Schottky diodes on silicon-on-insulator (SOI) substrates that operate above 60 volts face challenges due to bias effects from the handle wafer of the SOI substrate.
Innovation Solution
A semiconductor device with a Schottky diode on an SOI substrate, 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, which helps mitigate bias effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the lateral dimensions are increased to extend breakdown voltage, then the breakdown voltage is improved, but the bias effects from the handle wafer worsen
Solution Approach 1:
A field plate structure is introduced as an intermediary element between the Schottky diode and the handle wafer. The field plate includes a conductive layer extending over a dielectric layer, creating a controlled electric field distribution that mediates the interaction between the diode and substrate, thereby reducing bias effects while maintaining high breakdown voltage
Solution Approach 2:
The solution transitions from a purely lateral dimension approach to a three-dimensional structure by adding vertical field plate elements. The field plate extends in the vertical dimension above the semiconductor layer, allowing electric field management in multiple dimensions simultaneously - maintaining lateral breakdown voltage while controlling vertical bias effects
2Object-affected harmful factors
If a guard ring structure is added to reduce bias effects, then the bias effects are improved, but the device complexity worsens
Solution Approach 1:
The field plate structure performs multiple functions simultaneously: it acts as a guard ring to reduce bias effects, serves as an electric field distribution element to enhance breakdown voltage, and provides a simplified continuous structure that integrates with existing diode geometry. This multi-functionality reduces overall device complexity while achieving bias effect mitigation
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 extends the breakdown voltage and improves the operational efficiency of Schottky diodes on SOI substrates by reducing bias effects and enhancing current handling capabilities.
Implementation Method 1
A barrier of the Schottky diode is formed at an interface between the Schottky barrier region and the metal-containing layer
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.