Power MOSFET Gate-Source ESD Diode for Leakage and Breakdown Control
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Solution Overview
Problem
Power MOSFETs face challenges in protecting against electrostatic discharge (ESD) and maintaining breakdown voltage, as existing ESD diode structures can lead to leakage and reduced reliability in high-voltage applications.
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 reduce peak electric field strengths, thereby enhancing breakdown voltage and preventing 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 against ESD, then gate protection is improved, but leakage increases and breakdown voltage decreases
Solution Approach 1:
A body ring structure is introduced as an intermediary element between the ESD diode and the substrate. This body ring acts as a mediator that redistributes the electric field, preventing direct high-field stress on the ESD diode while maintaining ESD protection functionality. The body ring structure with its specific doping profile serves as a buffer zone that reduces peak electric field strength and prevents leakage paths.
Solution Approach 2:
The patent modifies the doping concentration and distribution in the body ring structure to optimize the electric field profile. By carefully controlling the doping parameters (concentration, depth, width), the structure achieves a balance between ESD protection, leakage reduction, and breakdown voltage enhancement. The doping parameters are specifically tuned to create a gradual field distribution rather than sharp transitions.
2Reliability
If a back-to-back ESD diode structure is connected between gate and source to protect against ESD, then gate protection is improved, but breakdown voltage is reduced
Solution Approach 1:
The body ring structure employs specific doping parameter adjustments to enhance breakdown voltage. The doping concentration in the body ring is optimized to create a wider depletion region that can sustain higher voltages. By controlling the doping depth and concentration gradient, the structure extends the breakdown voltage beyond what the ESD diode alone could provide, achieving both protection and high-voltage capability.
Solution Approach 2:
The patent transitions from a two-dimensional ESD diode structure to a three-dimensional body ring structure that extends vertically and horizontally. This dimensional expansion creates additional field distribution pathways, allowing the electric field to be managed in multiple spatial dimensions. The body ring's vertical extension into the substrate provides an additional dimension for voltage sustainment.
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 proposed design effectively protects against ESD, improves breakdown voltage, and reduces leakage, ensuring reliable operation in high-voltage applications by dispersing electric fields and maintaining even field distribution.
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
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.