Semiconductor Device Protruding Electrode Trench Self Turn-On
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Solution Overview
Problem
In synchronous buck converters, the self turn-on phenomenon occurs due to increased voltage variation rates, leading to unreliable switching states in semiconductor devices, particularly in high-frequency operations, where the off-state of the low-side switching element is inadvertently turned on due to gate-drain capacitance, necessitating reduced gate resistance and capacitance ratios.
Innovation Solution
The semiconductor device incorporates a structure with a first trench and a deeper second trench, featuring a gate electrode and a protruded electrode with varying insulator film thicknesses, which increases gate-source capacitance and forms a depletion layer to reduce on-resistance and enhance breakdown voltage, while the protruded electrode is connected to the source electrode to manage electric fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the overlapped area between gate electrode and n-type epitaxial layer is reduced to minimize gate-drain capacitance, then the gate-drain capacitance ratio is improved, but the depletion effect from gate electrode toward n-type epitaxial layer cannot be exerted sufficiently, resulting in insufficient on-resistance reduction
Solution Approach 1:
The invention introduces a protruded electrode that extends in the depth dimension (z-direction) beyond the gate electrode, creating a three-dimensional structure. This additional dimensional extension allows the electrode to overlap with the n-type epitaxial layer in the depth direction, enabling depletion effect without increasing the planar overlapped area between gate electrode and epitaxial layer, thus resolving the contradiction between minimizing gate-drain capacitance and achieving sufficient depletion effect for low on-resistance
Solution Approach 2:
The conducting electrode is segmented into two functional parts: the gate electrode portion that controls the channel, and the protruded electrode portion that extends deeper into the drift region to enhance depletion effect. This segmentation allows each part to perform its specific function optimally - the gate electrode minimizes gate-drain capacitance while the protruded portion provides additional depletion effect to reduce on-resistance
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 effectively prevents self turn-on phenomena, reduces on-resistance, and enhances breakdown voltage, ensuring reliable high-frequency switching operations by optimizing capacitance ratios and electric field management.
Implementation Method 1
the protruded electrode 9 connected to the source electrode 11 forms a depletion layer widely in the n− type drift layer 2
Implementation Method 2
the insulator film 7b having a larger thickness than that of the insulator film 7a relieves an electric field applied across the n− type drift layer 2
Implementation Method 3
increases gate-source capacitance and forms a depletion layer to reduce on-resistance and enhance breakdown voltage
Data Source
AI summary
A semiconductor device comprises a semiconductor region of the first conduction type. A first main electrode is connected to the semiconductor region. A base region of the second conduction type is formed on the semiconductor region. A diffused region of the first conduction type is formed on the base region. A second main electrode is connected to the diffused region and the base region. A first trench is formed extending from a surface of the diffused region to the semiconductor region. A second trench is formed from the first trench deeper than the first trench. A gate electrode is formed on a side of the first trench via a first insulator film. A protruded electrode is formed in the second trench via a second insulator film as protruded lower than the gate electrode.