Bootstrap Schottky Diode Structure for High-Voltage Leakage Control
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Solution Overview
Problem
Bootstrap Schottky diodes in high voltage semiconductor devices experience significant leakage current and require protection from high voltages to operate reliably.
Innovation Solution
The semiconductor device incorporates a junction isolation region with a deep n-type well region, a Schottky diode with an extended n-type buried layer, and a guard ring structure to reduce leakage current and protect the diode from high voltage, featuring a p-type buried layer and multiple deep p-type well regions to enhance breakdown voltage and electric field distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a Schottky diode is used as a bootstrap diode, then the diode can operate at high voltage, but a large amount of leakage current is generated in the substrate direction
Solution Approach 1:
An n-type buried layer (NBL) is introduced as an intermediary between the Schottky diode and the substrate. This NBL acts as a mediator that blocks the leakage current path from the diode to the substrate while maintaining the high breakdown voltage capability of the Schottky diode structure.
Solution Approach 2:
The leakage current path is extracted and separated from the main diode structure by creating a dedicated NBL region. This extracted layer specifically addresses the leakage issue without interfering with the primary rectification function of the Schottky diode.
2Power
If a Schottky diode is used in a bootstrap circuit, then the circuit can provide high positive voltage to the gate, but the diode requires protection from high voltage to operate reliably
Solution Approach 1:
The n-type buried layer is positioned beforehand between the diode and substrate to cushion or absorb the harmful effects of high voltage stress. This pre-positioned protective layer prevents direct exposure of the diode to damaging high voltage conditions, ensuring reliable operation.
3Strength
If deep n-type well regions and multiple deep p-type well regions are added to protect the Schottky diode, then breakdown voltage performance is improved, but device complexity increases
Solution Approach 1:
The protective structure merges multiple functions into a single integrated design. The deep n-type well and deep p-type wells are combined with the Schottky diode to form a unified device structure that provides both protection and high breakdown voltage performance without requiring separate protective components.
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 reduces leakage current and protects the Schottky diode from high voltage, ensuring reliable operation and improved breakdown voltage performance.
Implementation Method 1
an anode Schottky barrier layer formed in contact with the DNW and disposed between the two deep p-type well regions
Implementation Method 2
a first deep p-type well region (DPW) and an n-type well region (NW) formed on the NBL, a p-type buried layer (PBL) formed in contact with the NBL, and a second DPW formed on the PBL
Data Source
AI summary
A semiconductor device includes a junction isolation region, a Schottky diode including an n-type buried layer (NBL), an anode electrode, and a cathode electrode formed on the NBL, and a guard ring surrounding the Schottky diode. A source electrode of the junction isolation region is electrically connected to the cathode electrode of the Schottky diode.