Power MOSFET Floating Electrode Layout for Low On-Resistance
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Solution Overview
Problem
Power MOSFETs with low to middle withstand voltages face challenges in improving performance without increasing the doping concentration of the N-type drift region, leading to decreased withstand voltage and increased temperature dependency.
Innovation Solution
A semiconductor device with a floating electrode placed between the field plate electrode and the gate electrode, where the thickness relationship of insulating films between the field plate electrode, floating electrode, and gate electrode satisfies T1>T2>T3, reducing on-resistance and enhancing withstand voltage without increasing doping concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the doping concentration of the N-type drift region is increased to reduce resistance, then the on-resistance decreases, but the withstand voltage decreases and temperature dependency increases
Solution Approach 1:
The patent introduces a floating electrode between the field plate electrode and the gate electrode, segmenting the electric field distribution. This creates multiple electric field regions with different characteristics, allowing the drift region to maintain lower doping concentration while achieving both low on-resistance and high withstand voltage through distributed field management
Solution Approach 2:
The floating electrode creates localized electric field enhancement in specific regions. By positioning the floating electrode at appropriate locations and controlling the insulating film thicknesses (T1>T2>T3), the electric field is concentrated where needed for breakdown voltage control, while other regions maintain low resistance characteristics
2Productivity
If the doping concentration of the N-type drift region is increased to improve current conduction, then the on-current increases, but the temperature dependency increases
Solution Approach 1:
The floating electrode segments the current path into multiple regions with different doping requirements. The drift region can maintain lower doping concentration for reduced temperature dependency, while the floating electrode structure provides alternative current paths that maintain high on-current through field-induced carrier accumulation
3Reliability
If the insulating film thickness between the field plate electrode and the N-type drift region is increased to enhance withstand voltage, then the breakdown voltage increases, but the electric field balance is disrupted
Solution Approach 1:
The patent applies different insulating film thicknesses at different locations: T1 between the field plate electrode and drift region, T2 between the floating electrode and drift region, and T3 between the gate electrode and channel region, with T1>T2>T3. This local differentiation allows each region to optimize its electric field characteristics for its specific function while maintaining overall system balance
Solution Approach 2:
By controlling the insulating film thickness parameters (T1, T2, T3) to satisfy T1>T2>T3, the patent optimizes the electric field distribution. This parameter control allows the field plate electrode region to have sufficient insulation for breakdown voltage while the floating electrode and gate electrode regions maintain appropriate field strengths for their respective functions
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 improves on-current and withstand voltage while minimizing the risk of self-turn-on malfunctions, achieving better performance without increasing doping concentration in the N-type drift region.
Implementation Method 1
When a thickness of an insulating film between the field plate electrode and an N-type drift region is T1, a thickness of the insulating film between the floating electrode and the N-type drift region is T2, and a thickness of the insulating film between the gate electrode and a P-type channel region is T3, a relationship of T1>T2>T3 is satisfied
Data Source
AI summary
Provided is a semiconductor device including a field plate electrode, a floating electrode, and a gate electrode and satisfying a relationship of T1>T2>T3, where T1 is a thickness of an insulating film between the field plate electrode and an N-type drift region, T2 is a thickness of the insulating film between the floating electrode and the N-type drift region, and T3 is a thickness of the insulating film between the gate electrode and a P-type channel region.