MOS Power Device Trench Source Field Electrode
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Solution Overview
Problem
Existing power semiconductor devices face challenges in balancing breakdown voltage and on-resistance, with current solutions either limiting switching speed or increasing production costs and reducing cell density.
Innovation Solution
A MOSgated power semiconductor device design featuring an insulated gate electrode and a source field electrode within the same trench, with local connection to the source contact to reduce contact resistance, allowing for faster switching speeds and improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If additional trenches are created to support field electrodes electrically connected to the source contact, then the switching speed is improved, but the production cost increases and cell density decreases
Solution Approach 1:
The patent combines the gate electrode and source field electrode into a single common trench structure. The source field electrode is positioned at the bottom of the trench while the gate electrode is positioned above it, both within the same trench. This merging eliminates the need for separate trenches for each electrode type, reducing the number of masking steps required and maintaining high cell density while still providing electrical connection from the source contact to the field electrode for improved switching speed.
Solution Approach 2:
The patent utilizes vertical positioning within the trench to differentiate electrode functions. The source field electrode is placed at the bottom of the trench and the gate electrode is placed above it, creating a vertical arrangement. This dimensional organization allows both electrodes to coexist in the same trench space without interfering with each other, enabling fast switching through proper electrical connection while maintaining compact cell structure.
2Productivity
If the cell pitch is reduced to increase current carrying capability, then the device density is improved, but the contact resistance between source contact and source field electrode increases
Solution Approach 1:
The patent transitions from a horizontal contact arrangement to a vertical contact arrangement within the trench. The source field electrode extends vertically within the trench structure, allowing the source contact to connect to it through the trench opening. This vertical configuration maintains effective contact area even when cell pitch is reduced horizontally, thereby maintaining low contact resistance while increasing current carrying capability through higher cell density.
3Strength
If buried electrodes are disposed within the same trench as gate electrodes to improve breakdown voltage, then the breakdown voltage is improved, but the switching speed is limited due to remote electrical connection
Solution Approach 1:
The patent extracts the source field electrode from the conventional remote connection configuration and repositions it within the same trench as the gate electrode, but at the bottom of the trench. This extraction from the remote connection arrangement allows the source field electrode to be locally connected to the source contact through the trench opening, enabling fast switching while maintaining the breakdown voltage improvement achieved by having both electrodes in the same trench structure.
Data Source
AI summary
A power semiconductor device which includes a source field electrode, and at least one insulated gate electrode adjacent a respective side of the source field electrode, the source field electrode and the gate electrode being disposed in a common trench.