Split-Gate MOSFET Super Junction Structure for Lower On-Resistance
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Solution Overview
Problem
Traditional silicon-based MOSFETs have high on-resistance, limiting their applications, and existing super junction structures are complex and costly to manufacture.
Innovation Solution
A split gate MOSFET is developed with an epitaxy layer of a first conductivity type on a substrate, where trenches are formed, and impurities of a second conductivity type are implanted into the trenches to create alternately arranged doping areas, simplifying the manufacturing process and reducing on-resistance through a super junction structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional silicon-based MOSFETs are used, then the manufacturing process is simple, but the on-resistance is high
Solution Approach 1:
The patent divides the gate structure into multiple segments (first gate electrode and second gate electrode) separated by a first insulating layer. This segmentation allows independent control of different regions, enabling the formation of super junction structures that reduce on-resistance while maintaining manufacturing feasibility through modular fabrication processes
Solution Approach 2:
The patent employs composite material structures including the combination of semiconductor layers with different doping types (first conductivity type and second conductivity type), insulating materials, and conductive gate electrodes. This composite approach creates super junction regions that simultaneously achieve low on-resistance and manageable manufacturing complexity
2Object-affected harmful factors
If super junction structures are formed using multi-epitaxial growth and implant, then the on-resistance is reduced, but the manufacturing process becomes complicated and costly
Solution Approach 1:
The patent performs preliminary doping actions during the epitaxial growth process itself, forming doped and undoped regions in alternating layers before final device fabrication. This preliminary action eliminates the need for subsequent complex ion implantation steps to create super junction structures, simplifying the overall manufacturing process while achieving the desired low on-resistance
Solution Approach 2:
The patent extracts the super junction structure formation from the complex multi-step processes (multi-epitaxial growth with separate implant steps) and integrates it into a simplified epitaxial growth process with preliminary doping. This extraction removes unnecessary manufacturing complexity while retaining the essential super junction functionality for reducing 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
The solution simplifies the manufacturing process, reduces costs, and significantly decreases on-resistance by forming a super junction structure with alternately arranged doping areas, enhancing the performance of the MOSFET.
Implementation Method 1
implanting first impurities with a second conductivity type in a bottom and a sidewall of each of the trenches by an ion implanting process
Implementation Method 2
driving the first impurities to form a plurality of first doping areas in the epitaxy layer, wherein each of the first doping areas is diffused from the bottom and the sidewall of each of the trenches
Data Source
AI summary
The present disclosure provides a split gate MOSFET and a manufacturing method thereof. An epitaxy layer with a first conductivity type is formed on a substrate. A plurality of trenches are formed in the epitaxy layer. Impurities with a second conductive type is implanted and driven to the trenches to form a plurality of first doping areas. Since the first doping areas and none-doping areas of the epitaxy layer are alternately arranged with each other, and the first conductive type and the second conductive type are different conductivity types selected from P type or N type, the split gate MOSFET including the super junction structure is manufactured, and the advantages of simplifying manufacturing process, reducing cost and greatly reducing the on-resistance are achieved.