Shielding Electrode for High-Voltage Semiconductor Field Plates
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Solution Overview
Problem
Conventional high-voltage semiconductor devices experience reduced withstand voltage due to electric field concentration near the semiconductor surface, particularly affecting the first field plates closest to the source side, which limits the depletion layer extension and overall voltage tolerance.
Innovation Solution
Incorporation of a shielding electrode between the first field plate closest to the source side and the high-voltage wiring conductor to reduce electrostatic coupling and electric field concentration, utilizing a structure where the shielding electrode is wider than the first field plate and connected to the source potential, thereby mitigating the influence of the high-voltage wiring conductor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-voltage wiring conductor is provided to extend over the gate electrode and first field plates for electrical connection, then electrical connectivity is improved, but electric field concentration occurs in the vicinity of the upper surface of the semiconductor layer, reducing withstand voltage
Solution Approach 1:
A shielding electrode is introduced as an intermediary element between the high-voltage wiring conductor and the first field plates. This shielding electrode acts as a mediator that blocks the harmful electrostatic coupling and electric field concentration from the wiring conductor, preventing the adverse effect on the semiconductor layer while maintaining the electrical connectivity function of the wiring conductor.
Solution Approach 2:
The high-voltage wiring conductor, which initially causes harmful electric field concentration, is converted into a beneficial configuration by adding the shielding electrode. The shielding electrode utilizes the presence of the wiring conductor to establish a controlled electrostatic shield, transforming the harmful electric field effect into a controlled shielding effect that protects the first field plates and improves overall device reliability.
2Area of stationary object
If the first field plates are positioned close to the source side for compact design, then device area is reduced, but the potential on these field plates is increased due to electrostatic coupling with the high-voltage wiring conductor, limiting depletion layer extension and reducing withstand voltage
Solution Approach 1:
The shielding electrode serves as a protective intermediary positioned between the compact first field plates and the high-voltage wiring conductor. This allows the first field plates to maintain their close positioning for compact device area while the shielding electrode blocks the harmful electrostatic coupling that would otherwise increase their potential and reduce withstand voltage.
Solution Approach 2:
The shielding electrode is positioned in advance to prevent the harmful electrostatic coupling effect before it can affect the first field plates. By establishing this protective barrier beforehand, the potential increase on the first field plates is prevented, allowing the depletion layer to extend properly and maintain high withstand voltage despite the compact layout.
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 introduction of the shielding electrode effectively reduces electric field concentration and enhances the semiconductor device's withstand voltage by minimizing the impact of the high-voltage wiring conductor on the first field plate, thereby improving voltage tolerance without altering the fundamental structural voltage determination.
Implementation Method 1
the potential on the first field plate positioned closest to a source side is increased due to electrostatic coupling with the high-voltage wiring conductor
Implementation Method 2
electric field concentration occurs in the vicinity of the upper surface of the semiconductor layer
Data Source
AI summary
A gate electrode 20 and first field plates 22a to 22d and 23 are provided on a field oxide film 19. The gate electrode 20 and first field plates 22a to 22d and 23 are covered with an insulating film 24. A high-voltage wiring conductor 28 is provided on the insulating film 24. A shielding electrode 29 is provided between the first field plate 22a positioned closest to a source side and the high-voltage wiring conductor 28.