Integrated MOSFET Schottky Diode Leakage Reduction
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Solution Overview
Problem
Current trench technologies for Schottky diodes in power MOSFETs with higher breakdown voltages (40-300V) suffer from higher leakage and higher forward voltage (Vf) issues, making them unsuitable for integrated Trench MOS Barrier Schottky (TMBS) devices.
Innovation Solution
Integration of a high-performance Schottky diode with a MOSFET having deep source field electrodes, utilizing two additional masks and a barrier metal process to form low reverse leakage and low Vf Schottky diodes, with appropriately chosen mesa width, allowing for higher current operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional trench process flow is used to form Schottky diode in power MOSFET with higher breakdown voltages (40-300V), then the device structure is simple and manufacturable, but the Schottky diode exhibits higher reverse leakage and higher forward voltage (Vf)
Solution Approach 1:
The patent applies local quality by creating different mesa width regions: narrower mesas in the Schottky diode region to reduce reverse leakage and forward voltage, while maintaining wider mesas in MOSFET regions for proper device operation. This spatial variation in geometric parameters optimizes performance for each device type within the same integrated structure.
Solution Approach 2:
The invention changes the mesa width parameter specifically in the Schottky diode region compared to traditional processes. By reducing the mesa width in the Schottky region, the patent achieves lower reverse leakage and lower forward voltage without compromising the overall device manufacturability through standard trench isolation processes.
2Reliability
If Schottky diode is integrated with MOSFET having deep source field electrodes with appropriately chosen mesa width, then reverse leakage and Vf are reduced, but the device complexity increases due to additional masks and barrier metal process
Solution Approach 1:
The patent segments the device into distinct MOSFET regions and Schottky diode regions with different mesa widths. This segmentation allows independent optimization of each device type while using a unified process flow, adding minimal complexity through strategic use of additional photomasks to define the different regional geometries.
Solution Approach 2:
The deep source field electrode structure serves multiple functions: it provides field control for MOSFET operation and simultaneously enables the formation of low-leakage Schottky diodes when combined with appropriate mesa width. This multi-functionality reduces the need for separate specialized structures for each device type.
3Productivity
If mesa width is appropriately chosen for Schottky region, then Schottky diode can operate at higher current levels with lower Vf, but manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes the mesa width parameter in the Schottky region to enable higher current operation with reduced forward voltage. By carefully selecting this geometric parameter, the invention achieves improved current handling capability while relying on standard semiconductor fabrication precision to maintain control over the mesa dimensions.
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 achieves significantly lower leakage and Vf compared to traditional trench processes, enabling the Schottky diode to operate at higher current levels and outperform MOSFETs with pn junction diodes.
Implementation Method 1
a Schottky barrier metal body making Schottky contact with the source contact
Data Source
AI summary
A power semiconductor device that includes a trench power MOSFET with deep source field electrodes and an integrated Schottky diode.