Assistant Gate Capacitive Coupling for Schottky Diode Breakdown Voltage
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Solution Overview
Problem
Schottky diodes have low breakdown voltage, which limits their application in high voltage electronic circuits, and existing solutions fail to improve breakdown voltage without affecting forward current and device pitch.
Innovation Solution
A high voltage device with an assistant gate electrically connected to a Schottky diode, where the assistant gate is capacitively coupled with an ion well to generate an extended depletion region, increasing breakdown voltage without affecting forward current or device pitch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a Schottky diode is used for fast switching applications, then switching speed and current density are improved, but breakdown voltage is reduced
Solution Approach 1:
An assistant gate is introduced as an intermediary element between the control gate and the ion well. This assistant gate, positioned on the isolation structure, capacitively couples with the ion well to generate an extended depletion region that enhances breakdown voltage without interfering with the fast switching characteristics of the Schottky diode
Solution Approach 2:
The assistant gate is specifically positioned only on the isolation structure surrounding the Schottky diode, creating a localized electric field enhancement in the reverse bias region. This local modification extends the depletion region precisely where needed for breakdown voltage enhancement without affecting the forward conduction path
2Reliability
If the breakdown voltage of a Schottky diode is improved, then high voltage application capability is enhanced, but forward current characteristics may be affected
Solution Approach 1:
The assistant gate modifies the electric field distribution locally in the reverse bias region through capacitive coupling with the ion well. This localized field enhancement increases breakdown voltage without altering the forward conduction characteristics, as the modification is confined to the isolation structure region and does not affect the Schottky junction's forward current flow
3Reliability
If the breakdown voltage is increased by modifying the device structure, then high voltage performance is improved, but device pitch may be increased
Solution Approach 1:
The isolation structure serves dual functions: it provides electrical isolation for the Schottky diode and supports the assistant gate for breakdown voltage enhancement. By utilizing the existing isolation structure as the substrate for the assistant gate, the invention achieves breakdown voltage improvement without requiring additional space that would increase device pitch
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 enhances the breakdown voltage of the high voltage device by generating an extended depletion region when operated in reverse mode, improving its performance without compromising forward current or device pitch.
Implementation Method 1
The assistant gate provided on the isolation structure capacitively couples with the first ion well directly below the isolation structure and an extended depletion region is generated
Implementation Method 2
an extended depletion region is generated, thereby achieving the purpose of increasing the breakdown voltage of the high voltage device
Data Source
AI summary
A high voltage device includes a semiconductor substrate, an ion well, a Schottky diode in the ion well, an isolation structure in the ion well surrounding the Schottky diode, and an assistant gate surrounding the Schottky diode. The assistant gate is disposed only on the isolation structure and is not in direct contact with the ion well.