IGBT Dummy Gate Resistor Segmentation
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Solution Overview
Problem
Conventional insulated gate bipolar transistors (IGBTs) face challenges in reducing on-resistance and improving switching speed while preventing gate voltage oscillation and overshoot, particularly due to high gate capacitance and non-linear switching characteristics.
Innovation Solution
The semiconductor device incorporates a trench IGBT design with a dummy trench gate electrode and divided gate resistors, where the CR time constant of the trench gate electrode is less than that of the dummy trench gate electrode, allowing independent control of current flow and reducing gate capacitance, thereby enhancing switching speed and preventing oscillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a dummy trench gate electrode is added to prevent hole emission and reduce on-resistance, then the on-resistance decreases, but the gate capacitance increases and switching speed deteriorates
Solution Approach 1:
The gate electrode system is segmented into two distinct types: trench gate electrodes that extend to the n base region for current conduction, and dummy trench gate electrodes that terminate before the n base region for hole emission prevention. This segmentation allows each component to perform its specific function independently, resolving the contradiction between reducing on-resistance and maintaining switching speed.
2Reliability
If gate resistance is increased to prevent gate voltage oscillation, then oscillation is suppressed, but switching speed decreases
Solution Approach 1:
A gate resistor is introduced as an intermediary element between the gate electrode and the control circuit. This resistor acts as a damping element that suppresses gate voltage oscillation and overshoot without significantly impacting the switching speed, as the primary current path remains through the low-resistance trench gate electrodes.
3Manufacturing precision
If the trench gate electrode structure is optimized for low on-resistance, then on-resistance decreases, but gate voltage oscillation and overshoot increase
Solution Approach 1:
The dummy trench gate electrodes provide a feedback mechanism by creating a capacitive coupling that counteracts voltage oscillations in the main trench gate electrodes. The dummy electrodes, being electrically isolated from the n base region, create a stabilizing effect that dampens oscillations while maintaining the low on-resistance characteristics of the primary gate structure.
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 achieves low on-resistance, high switching speed, and prevents gate voltage oscillation, while also simplifying the manufacturing process and reducing chip area.
Implementation Method 1
a positive voltage is applied to a gate electrode to form a channel in the p base region. Then, holes are injected from the collector region to the n base region at the same time as electrons are injected from the emitter region to the n base region. Then, a current flows between the collector electrode and the emitter electrode.
Implementation Method 2
A CR time constant of the trench gate electrode is less than a CR time constant of the dummy trench gate electrode. This design achieves low on-resistance, high switching speed, and prevents gate voltage oscillation.
Data Source
AI summary
A semiconductor device according to an embodiment includes a semiconductor layer having a first and a second plane; emitter and collector electrode; a trench gate electrode extending in a first direction substantially parallel to the first plane; a dummy trench gate electrode extending in the first direction; a p base region; an emitter region; an n base region; a collector region; a trench gate insulating film; a dummy trench gate electrode; a dummy trench gate insulating film; a first gate pad electrode connected to the trench gate electrode and the dummy trench gate electrode; a first electric resistor connected between the first gate pad electrode and the trench gate electrode, and a second electric resistor connected between the first gate pad electrode and the dummy trench gate electrode. A CR time constant of the trench gate electrode is less than a CR time constant of the dummy trench gate electrode.