Power MOSFET Gate-Source ESD Diode with Body Ring Structure
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Solution Overview
Problem
Power MOSFETs, particularly vertical power MOSFETs, are vulnerable to electrostatic discharge (ESD) damage due to excessive gate voltage, leading to breakdown and potential damage, and existing ESD protection structures do not adequately enhance breakdown voltage or prevent leakage.
Innovation Solution
A power MOSFET design incorporating a gate-source ESD diode structure with a breakdown voltage enhancement and leakage prevention structure, featuring a body ring structure underneath the ESD diode to disperse electric fields and improve breakdown voltage while reducing leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a back-to-back ESD diode structure is connected between gate and source to protect from ESD, then gate protection reliability is improved, but breakdown voltage is reduced and leakage increases
Solution Approach 1:
A body ring structure is introduced as an intermediary element between the ESD diode and the substrate. This body ring structure acts as a mediator that disperses the electric field, preventing direct high-stress interaction between the ESD diode and the substrate, thereby maintaining both protection reliability and breakdown voltage
Solution Approach 2:
The body ring structure is positioned specifically underneath the ESD diode where the electric field concentration is most severe. This localized structural enhancement provides targeted electric field dispersion exactly where needed, protecting the gate while maintaining overall device breakdown characteristics
2Reliability
If a back-to-back ESD diode structure is connected between gate and source to protect from ESD, then gate protection reliability is improved, but leakage current increases
Solution Approach 1:
The body ring structure serves as an intermediary that modifies the electric field distribution between the ESD diode and substrate. By introducing this intermediate structure, the direct path for leakage current is interrupted and the electric field is redistributed, reducing leakage while maintaining ESD protection functionality
Solution Approach 2:
The body ring structure changes the electrical parameters (electric field distribution, potential gradient) in the region underneath the ESD diode. This parameter modification creates a more favorable electric field profile that reduces leakage current while preserving the ESD clamping action
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 design effectively protects the MOSFET from ESD by enhancing breakdown voltage and minimizing leakage, ensuring reliable operation under high voltage and current conditions.
Implementation Method 1
a breakdown voltage enhancement and leakage prevention structure formed underneath the gate-source ESD diode structure
Implementation Method 2
the gate of a vertical power MOSFET is a crucial element. Excessive voltage at the gate relative to the source can lead to breakdown and damage. To protect the gate of the vertical power MOSFET from ESD, a back-to-back ESD diode structure may be connected between the gate and source terminals
Data Source
AI summary
An apparatus includes a drain and a source on opposing sides of an epitaxial layer, a plurality of gates formed in the epitaxial layer, a source contact connected to the source, a gate contact connected to the plurality of gates, a gate-source electrostatic discharge (ESD) diode connected between the gate contact and the source contact, and a breakdown voltage enhancement and leakage prevention structure formed underneath the gate-source ESD diode structure, wherein the breakdown voltage enhancement and leakage prevention structure comprises a body ring structure.