Vertical MOSFET Mesa Structure for Low Leakage and High Breakdown
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Solution Overview
Problem
Existing vertical MOSFETs face challenges in reducing leakage current and ensuring high breakdown voltage due to the absence of a p-type base layer, particularly at the trench contact parts, which affects their performance in applications requiring high switching efficiency and reverse current handling.
Innovation Solution
Incorporating a p-type second semiconductor layer in the termination region to form a Schottky junction with the second electrode, and utilizing trench structure parts with insulating films to enhance depletion layers for reducing leakage current and increasing breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a p-type base layer is not included in the vertical MOSFET structure, then the device complexity is reduced and manufacturing is simplified, but the leakage current increases and breakdown voltage decreases
Solution Approach 1:
The patent extracts and removes the p-type base layer from the vertical MOSFET structure, creating a p-type-free configuration. This extraction simplifies the device structure and manufacturing process while the patent compensates for the resulting performance degradation through alternative design features such as optimized drift layers and termination structures
Solution Approach 2:
The patent changes the electrical parameters of the remaining layers to compensate for the absence of the p-type base layer. This includes adjusting the doping concentrations, thicknesses, and material compositions of the drift layer and other components to achieve the desired breakdown voltage and leakage current characteristics without the traditional p-type base structure
2Manufacturing precision
If the trench contact part uses a simplified structure without p-type base, then the manufacturing precision requirements are reduced, but the leakage current control becomes insufficient
Solution Approach 1:
The patent converts the potentially harmful effect of the simplified trench contact structure (which would normally increase leakage) into a benefit by designing the drift layer and termination structures to actively suppress leakage currents. The simplified structure becomes advantageous by reducing manufacturing complexity while the alternative designs compensate for leakage control
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 proposed configuration effectively reduces leakage current and enhances breakdown voltage, ensuring high switching efficiency and reverse current handling capabilities in semiconductor devices.
Implementation Method 1
an off-state is realized by a depletion layer extending from a Schottky junction between a source electrode and a semiconductor layer
Implementation Method 2
Incorporating a p-type second semiconductor layer in the termination region to form a Schottky junction with the second electrode, and utilizing trench structure parts with insulating films to enhance depletion layers
Data Source
AI summary
A semiconductor device includes a first electrode; a first semiconductor layer including a plurality of mesa parts; a second electrode positioned in a recess provided in an upper portion of the mesa part; a gate electrode adjacent to the mesa part; an insulating film located between the gate electrode and the mesa part; and a second semiconductor layer contacting an end portion of the second electrode. The mesa part includes a first side surface facing the gate electrode via the insulating film in the first direction, and a second side surface positioned at a side opposite to the first side surface. The second electrode contacts the second side surface.