Power MOSFET Gate-Source ESD Diode Structure for Low Leakage
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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:
The ESD protection structure is segmented into multiple p-n+ diode pairs arranged in series between gate and source. Each diode pair consists of a p-type region and an n+ region, creating multiple breakdown stages that distribute the ESD energy dissipation, thereby maintaining protection reliability while managing breakdown voltage characteristics
Solution Approach 2:
The patent implements localized doped regions (p-type and n+ regions) specifically positioned to create ESD protection paths only where needed. The p-n+ structures are strategically placed in the semiconductor layer to provide ESD clamping at the gate-source junction without affecting the overall device breakdown voltage characteristics in other regions
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 ESD diode structure is pre-configured with specific doping concentrations and geometric dimensions during manufacturing to ensure that under normal operating conditions, the diodes remain reverse-biased and conduct minimal leakage current. The p-n+ structures are designed with doping profiles that minimize reverse leakage while maintaining ESD protection capability
Solution Approach 2:
The patent optimizes the doping concentrations, region dimensions, and geometric configuration of the p-n+ structures to achieve a balance between ESD protection effectiveness and leakage current minimization. By adjusting these parameters, the ESD diodes maintain high reliability for voltage clamping while keeping leakage current at acceptable levels
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 p-n+ structure is a common configuration for ESD protection diodes. The p-n+ structure helps create a structure having a low breakdown voltage, making the ESD diode structure suitable for clamping and diverting the excess voltage during an ESD event, thereby protecting the gate of the vertical power MOSFET from being damaged.
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.