Semiconductor Device With Non-Uniform Gate Insulating Film Thickness
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Solution Overview
Problem
Semiconductor devices, such as IGBTs, face issues with displacement current flowing in the gate electrode during turn-on and turn-off periods, leading to potential malfunctions and increased short-circuit currents, which can damage the device and reduce its withstand voltage.
Innovation Solution
The semiconductor device design includes a gate insulating film with varying thicknesses, where at least one part is thicker than others, specifically in contact with the carrier store layer, to reduce displacement current and enhance carrier accumulation, thereby lowering ON-voltage and reducing stationary losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the depth of the trench type gate electrode is reduced from the surface of the substrate, then displacement current flowing in the gate electrode is suppressed, but the main withstand voltage between emitter and collector is lowered
Solution Approach 1:
The gate insulating film is designed with non-uniform thickness, where the third part (in contact with substrate) is thicker than the first part (in contact with emitter layer). This local variation in thickness allows the gate electrode to extend deeper into the substrate without compromising the overall withstand voltage, as the thicker third part provides enhanced insulation at the critical substrate interface where displacement current occurs.
Solution Approach 2:
The invention changes the dimensional characteristics of the gate insulating film by creating thickness variation in the vertical dimension. The gate insulating film transitions from a uniform thickness structure to a graded thickness structure, with the third part having greater thickness to compensate for the extended gate electrode depth, thereby maintaining voltage blocking capability while suppressing displacement current.
2Reliability
If the gate insulating film thickness is increased to suppress displacement current, then device reliability improves, but manufacturing complexity increases
Solution Approach 1:
The gate insulating film is designed with non-uniform thickness, where the third part (in contact with substrate) is thicker than the first part (in contact with emitter layer). This local variation in thickness allows the gate electrode to extend deeper into the substrate without compromising the overall withstand voltage, as the thicker third part provides enhanced insulation at the critical substrate interface where displacement current occurs.
Solution Approach 2:
The invention applies parameter changes by varying the thickness of the gate insulating film across different regions. The thickness parameter transitions from a constant value to a spatially varying value, with the third part having greater thickness to suppress displacement current while the first part maintains appropriate thickness for emitter gate contact.
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 design effectively suppresses displacement current, preventing malfunctions and reducing ON-voltage, which enhances the reliability and efficiency of the semiconductor device by minimizing stationary losses and preventing short-circuit currents.
Implementation Method 1
when the potential of the drift layer or the carrier store layer varies, a displacement current flows in a gate electrode to change the gate potential
Data Source
AI summary
A semiconductor device including a first conductivity type substrate, a first conductivity type carrier store layer formed on an upper surface side of the substrate, a second conductivity type channel dope layer formed on the carrier store layer, a first conductivity type emitter layer formed on the channel dope layer, a gate electrode in contact with the emitter layer, the channel dope layer and the carrier store layer via a gate insulating film, and a second conductivity type collector layer formed on a lower surface side of the substrate, wherein the gate insulating film has a first part in contact with the emitter layer and the channel dope layer, a second part in contact with the carrier store layer, and a third part in contact with the substrate, and at least a part of the second part is thicker than the first part and the third part.