Shielded Gate Trench MOSFET Bottom-Shielding Electrode
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Solution Overview
Problem
Conventional power semiconductor devices face challenges in reducing gate-to-drain capacitance, which limits high-frequency power switching performance, and existing solutions increase source electrode resistance and manufacturing costs due to complex connections.
Innovation Solution
A semiconductor power device with a shielded gate trench (SGT) structure featuring a bottom-shielding electrode directly connected to the source voltage through a conductive polysilicon trench, reducing gate-to-drain capacitance by maintaining a direct electrical connection to the source metal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a source electrode is placed underneath the trenched gate to reduce gate-to-drain capacitance, then gate-to-drain capacitance is reduced, but source electrode resistance increases due to connection through edge area
Solution Approach 1:
The device is divided into discrete macro-cells, each with its own bottom-shielding electrode directly connected to source metal through source-connecting trenches. This segmentation eliminates the need for peripheral edge connections, reducing source electrode resistance while maintaining capacitance reduction benefits.
Solution Approach 2:
The connection path is moved from a two-dimensional peripheral edge connection to a three-dimensional vertical connection through source-connecting trenches. This dimensional change allows direct connection to source metal, reducing resistance while maintaining the shielding function.
2Object-generated harmful factors
If complex electrode connection structures are used to reduce gate-to-drain capacitance, then capacitance is reduced, but manufacturing cost increases due to extra masks and complex processes
Solution Approach 1:
The bottom-shielding electrode and source connection function are merged into a single integrated structure. The source-connecting trenches serve dual purposes: providing the shielding function and establishing the source voltage connection, eliminating the need for separate connection structures and masks.
Solution Approach 2:
The bottom-shielding electrode structure is designed to perform multiple functions simultaneously: reducing gate-to-drain capacitance through shielding and providing direct source voltage connection through the conductive polysilicon in source-connecting trenches. This multi-functionality reduces manufacturing complexity.
Data Source
AI summary
This invention discloses a semiconductor power device that includes a plurality of power transistor cells surrounded by a trench opened in a semiconductor substrate. At least one of the cells constituting an active cell has a source region disposed next to a trenched gate electrically connecting to a gate pad and surrounding the cell. The trenched gate further has a bottom-shielding electrode filled with a gate material disposed below and insulated from the trenched gate. At least one of the cells constituting a source-contacting cell surrounded by the trench with a portion functioning as a source connecting trench is filled with the gate material for electrically connecting between the bottom-shielding electrode and a source metal disposed directly on top of the source connecting trench. The semiconductor power device further includes an insulation protective layer disposed on top of the semiconductor power device having a plurality of source openings on top of the source region and the source connecting trench provided for electrically connecting to the source metal and at least a gate opening provided for electrically connecting the gate pad to the trenched gate.