Low Voltage Trench MOSFET ESD Protection Diode
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Solution Overview
Problem
Semiconductor devices face challenges in implementing effective electrostatic discharge (ESD) protection without increasing device size, as limited space restricts the allocation of sufficient ESD protection circuitry, which can lead to increased on-state resistance (RON).
Innovation Solution
The semiconductor device incorporates a diode formed between the gate metal and source metal, with a trench structure and gate electrode, allowing for increased ESD protection area without enlarging the device, and omits the resistor between the gate pad and gate metal to reduce RON.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ESD protection circuitry is added to protect against electrostatic discharge, then ESD resistance is improved, but device size increases
Solution Approach 1:
The patent combines the ESD protection function with the existing gate structure by forming a diode between the gate metal and source metal. This merges the protection circuitry into the existing device footprint, providing ESD protection without increasing overall device size.
Solution Approach 2:
The gate metal serves dual purposes: it functions as the gate electrode for transistor operation and simultaneously serves as one terminal of the ESD protection diode. This multi-functionality allows the same structure to provide both switching control and electrostatic discharge protection.
2Reliability
If ESD protection circuitry is added to protect against electrostatic discharge, then ESD resistance is improved, but on-state resistance increases
Solution Approach 1:
The patent removes the traditional resistor component from the gate structure that would increase on-state resistance. By eliminating this separate resistive element and using only the diode for protection, the on-state resistance is kept low while ESD protection remains effective.
Solution Approach 2:
The patent changes the protection mechanism from a resistive approach to a diode-based approach. The diode's nonlinear I-V characteristics provide ESD protection only when reverse-biased during ESD events, while presenting minimal resistance during normal forward conduction, thus maintaining low on-state resistance.
3Reliability
If diode area is increased to improve ESD protection, then ESD resistance is improved, but device size increases
Solution Approach 1:
The diode structure is nested within the existing gate and source metal regions. The diode's p-n junction is formed by doping regions that are integrated into the existing transistor structure, allowing the protection function to be embedded without requiring additional external space.
Solution Approach 2:
The patent extends the diode structure in the vertical dimension by forming the p-n junction through doping regions that extend into the substrate. This allows increased diode area for better ESD protection while maintaining a compact planar footprint.
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 enhances ESD resistance by increasing the diode area, allowing it to clamp high voltages effectively, while reducing the on-state resistance and device size by eliminating the need for additional space-consuming components.
Implementation Method 1
Electrostatic discharge (ESD) is a sudden flow of electricity between two electrically charged objects caused by contact, an electrical short, or dielectric breakdown.
Implementation Method 2
A diode is formed between the gate metal and the source metal
Implementation Method 3
a pair of first regions doped with a first conductivity type impurity, and a second region doped with a second conductivity type impurity
Data Source
AI summary
A semiconductor device includes a substrate and a source metal formed on the substrate. A gate pad is formed on the substrate adjacent to the source metal. A gate metal is formed on the substrate and surrounds the gate pad and the source metal. A first diode is formed between the gate metal and the source metal.