Power MOSFET Gate-Source ESD Diode Layout for Breakdown Control
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Solution Overview
Problem
Existing power MOSFETs face challenges in protecting the gate from electrostatic discharge (ESD) while maintaining high breakdown voltage and preventing leakage.
Innovation Solution
The implementation of a power MOSFET with a gate-source ESD diode structure and a breakdown voltage enhancement and leakage prevention structure, which includes an epitaxial layer, multiple gates, a body region, and a body ring structure underneath the gate-source ESD diode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a back-to-back ESD diode structure is connected between gate and source to protect the gate from ESD, then gate protection is improved, but breakdown voltage decreases and leakage increases
Solution Approach 1:
A body ring structure is introduced as an intermediary element between the ESD diode and the drain region. This body ring acts as a mediator that redistributes the electric field, preventing direct high-field stress on the drain while still allowing the ESD diode to protect the gate. The body ring structure thus enables both gate protection and maintained breakdown voltage.
Solution Approach 2:
The patent applies different doping concentrations and structural configurations to different regions: the ESD diode region has specific p-n+ junctions for protection, while the body ring has optimized doping to locally enhance breakdown voltage. This localized optimization allows the device to achieve both protection and high breakdown voltage in different areas simultaneously.
2Reliability
If a back-to-back ESD diode structure is connected between gate and source to protect the gate from ESD, then gate protection is improved, but leakage current increases
Solution Approach 1:
The body ring structure serves as an intermediary that provides a controlled path for leakage current, directing it through a larger area with optimized doping. This reduces the current density and minimizes the harmful leakage effect while still maintaining the ESD protection function of the diode structure.
Solution Approach 2:
The body ring structure extends the leakage current path from a one-dimensional junction path to a two-dimensional distributed path around the drain. This dimensional expansion distributes the leakage current over a larger area, reducing the peak leakage current and its harmful effects.
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
This configuration effectively protects the gate from ESD, enhances breakdown voltage, and reduces leakage, thereby improving the overall performance and reliability of the power MOSFET.
Implementation Method 1
a breakdown voltage enhancement and leakage prevention structure formed underneath the gate-source ESD diode structure
Data Source
AI summary
A method includes growing an epitaxial layer over a substrate, forming a plurality of gates in the epitaxial layer, forming a source in the epitaxial layer, forming a breakdown voltage enhancement and leakage prevention structure comprising a body ring structure in the epitaxial layer, forming a gate-source Electrostatic Discharge (ESD) diode structure over the epitaxial layer, forming a source contact connected to the source and a first terminal of the gate-source ESD diode structure, forming a gate contact connected to the plurality of gates and a second terminal of the gate-source ESD diode structure.