Shield Electrode Resistance Distribution for Switching Noise
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Solution Overview
Problem
Conventional semiconductor devices experience ringing and high surge voltages during switch-off due to high or low resistance shield electrodes, leading to erroneous operations and increased switching losses.
Innovation Solution
A semiconductor device with a shield electrode having a high resistance region on the drain side and a low resistance region on the gate side, made of the same or different materials, to attenuate potential changes and suppress ringing and surge voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a high resistance shield electrode is used, then ringing and surge voltage are suppressed, but gate voltage rises causing erroneous operation and switching speed decreases
Solution Approach 1:
The shield electrode is divided into two regions with different resistance characteristics: a high resistance region near the drain electrode to suppress ringing and surge voltage, and a low resistance region near the gate electrode to prevent gate voltage rise and maintain switching speed. This local differentiation of resistance properties resolves the contradiction between suppressing harmful voltage fluctuations and maintaining reliable operation.
2Object-affected harmful factors
If a high resistance shield electrode is used, then ringing and surge voltage are suppressed, but switching speed becomes slow increasing switching loss
Solution Approach 1:
The shield electrode employs spatially varying resistance: high resistance near the drain to attenuate voltage fluctuations and ringing, and low resistance near the gate to maintain fast charge/discharge capability. This local quality differentiation allows simultaneous achievement of ringing suppression and high switching speed.
3Productivity
If a low resistance shield electrode is used, then switching speed is maintained, but ringing and surge voltage cannot be suppressed
Solution Approach 1:
The shield electrode is configured with non-uniform resistance distribution: low resistance region near the gate electrode ensures fast switching by maintaining low impedance for charge/discharge currents, while the high resistance region near the drain electrode suppresses ringing and surge voltage by attenuating voltage fluctuations. This resolves the contradiction between switching speed and ringing suppression.
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 device effectively suppresses ringing and surge voltages during switch-off, preventing erroneous operations and reducing switching losses by optimizing the resistance distribution in the shield electrode.
Implementation Method 1
due to high internal resistance in the shield electrode, a change in potential of the drain electrode can be attenuated at the time of turning off a switch
Implementation Method 2
a gate insulating film interposed therebetween on a portion of the side wall
Data Source
AI summary
Provided is a semiconductor apparatus includes: a gate electrode disposed inside a trench and opposedly facing a p type base region with a gate insulating film interposed therebetween on a portion of a side wall; a shield electrode disposed inside the trench and positioned between the gate electrode and a bottom of the trench; an electric insulating region disposed inside the trench, the electric insulating region expanding between the gate electrode and the shield electrode, and further expanding along the side wall and the bottom of the trench so as to separate the shield electrode from the side wall and the bottom; a source electrode electrically connected to an n+ type source region and the shield electrode, wherein the shield electrode has a high resistance region positioned on an n+ drain region side, and a low resistance region positioned on a gate electrode side.