Vertical Trench Transistor Structure for High Voltage and Low Resistance
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Solution Overview
Problem
There is a need to improve the tradeoff between the resistance in the conductive state, dimensions, and the voltage held in the non-conductive state of transistors, particularly in field-effect transistors used in electronic devices that handle high voltages.
Innovation Solution
A transistor design featuring a semiconductor drain region with a first trench and a conductive element closer to the drain potential, a gate in a collinear second trench, and insulating regions with a thickness greater than the gate insulator, allowing for reduced resistance in the conductive state and increased voltage handling without increasing the transistor's surface area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the transistor dimensions are reduced to decrease occupied surface area, then the surface area is decreased, but the resistance in the conductive state increases
Solution Approach 1:
The patent transitions from a planar transistor structure to a vertical structure with trenches extending into the substrate. The drain region, gate, and conductive elements are arranged vertically along the trench depth rather than horizontally on the surface, allowing high voltage handling and low resistance to be achieved without increasing surface footprint.
Solution Approach 2:
The patent embeds multiple functional elements within the trench structure. The gate is positioned in a second trench, conductive elements are placed in a first trench, and insulating regions are nested between them. This nested arrangement packs multiple components into a compact vertical space, reducing surface area while maintaining electrical performance.
2Area of stationary object
If the transistor dimensions are reduced to decrease occupied surface area, then the surface area is decreased, but the voltage held in the non-conductive state decreases
Solution Approach 1:
By moving critical voltage-holding structures into the vertical dimension (trenches extending into the substrate), the patent achieves high voltage capability without increasing surface area. The depth of the trenches provides the necessary voltage standoff distance while keeping the surface footprint compact.
Solution Approach 2:
The patent changes the geometric parameters of the transistor structure by introducing deep trenches and vertical arrangements. This dimensional parameter change allows the voltage holding capability to be decoupled from the surface area, enabling high voltage operation in a compact form factor.
3Reliability
If the resistance in the conductive state is decreased to improve performance, then the resistance is decreased, but the occupied surface area increases
Solution Approach 1:
The conductive path is extended into the vertical dimension through the trench structure rather than expanding horizontally. Multiple conductive elements are arranged vertically to provide parallel conduction paths, reducing resistance without increasing the surface area occupied by the transistor.
Data Source
AI summary
An embodiment transistor comprises a semiconductor drain region delimited by a first trench, and, in the first trench, a first electrically conductive element electrically coupled to a node of application of a potential closer to a drain potential of the transistor than to a source potential of the transistor.