Super-junction Semiconductor Device Trench Segmentation
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Solution Overview
Problem
Conventional semiconductor devices with vertical diffused metal-oxide semiconductor field-effect transistors (VDSNOFETs) face limitations in increasing operating voltage without increasing on-resistance, as the doping concentration and thickness of the n-type epitaxial drift region are inversely related, and the use of column-shaped doping regions for charge balance restricts current passage area.
Innovation Solution
A semiconductor device with a super-junction structure is fabricated by forming alternately arranged first and second trenches in an epitaxial layer, where first and second doping regions of different conductivity types create a super-junction interface, allowing for deeper trench depths and increased current passage area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the doping concentration of the n-type epitaxial drift region is decreased to increase withstand voltage, then the break-down voltage increases, but the on-resistance increases
Solution Approach 1:
The drift region is segmented into alternating n-type and p-type columnar doping regions, creating a super-junction structure. This segmentation allows the n-type regions to carry current while the p-type regions provide charge balance, enabling higher breakdown voltage without proportionally increasing on-resistance compared to conventional uniform doping structures.
Solution Approach 2:
Different regions of the drift region are given different doping types and concentrations. The n-type regions have higher doping concentration for current conduction, while the p-type regions have lower doping concentration for charge balance, creating local quality variations that optimize both breakdown voltage and on-resistance characteristics.
2Strength
If the thickness of the n-type epitaxial drift region is increased to increase withstand voltage, then the break-down voltage increases, but the on-resistance increases
Solution Approach 1:
The drift region is divided into alternating n-type and p-type columnar structures. This segmentation enables the device to achieve higher breakdown voltage through the extended thickness of the super-junction structure while the alternating doping pattern maintains lower effective on-resistance by providing multiple current conduction paths through the n-type regions.
Solution Approach 2:
The drift region uses a composite structure combining n-type and p-type doped regions in an alternating pattern. This composite super-junction structure leverages the complementary properties of both doping types to achieve superior breakdown voltage and on-resistance characteristics compared to single-material doping approaches.
3Reliability
If the device size is increased to increase the total surface area of the n-type doping region for higher current capacity, then the current passage area increases, but the device footprint increases
Solution Approach 1:
The patent transitions from a planar doping structure to a vertical columnar super-junction structure. By utilizing the vertical dimension with deep trenches and alternating doping layers extending through the drift region thickness, the device achieves increased current capacity without proportionally increasing the horizontal device footprint, effectively using three-dimensional space optimization.
Solution Approach 2:
The drift region is segmented into multiple vertical columns of alternating n-type and p-type doping. This segmentation creates numerous parallel current conduction paths through the n-type columns, increasing total current capacity within a compact footprint by utilizing vertical space efficiency rather than horizontal expansion.
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 super-junction structure enhances the device's ability to withstand high voltages while reducing on-resistance by increasing the current passage area, allowing for improved performance without the need for larger device sizes.
Implementation Method 1
An interface between the first doping region and the second doping region forms a super-junction structure
Data Source
AI summary
A semiconductor device is disclosed. The device includes an epitaxial layer on a substrate, wherein the epitaxial layer includes first trenches and second trenches alternately arranged along a first direction. The epitaxial layer between the adjacent first and second trenches includes a first doping region and a second doping region, and the first doping region and the second doping region have different conductivity types. An interface is between the first doping region and the second doping region to form a super-junction structure. A gate structure is on the epitaxial layer. The epitaxial layer under the gate structure includes a channel extending along a second direction, and the first direction is perpendicular to the second direction.