Switching Device Trench Conductor Layer On-Resistance
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Solution Overview
Problem
The existing switching devices experience high resistance and loss when turned on due to the delayed contraction of the depletion layer around the specific part of the bottom semiconductor region, caused by the distance between the connection semiconductor region and the bottom semiconductor region.
Innovation Solution
A switching device with a semiconductor substrate featuring a conductor layer extending longitudinally within the trench, a bottom insulating layer, and a gate insulating layer, where the conductor layer is formed by alloying a metal layer with the trench bottom, allowing charges to reach the bottom semiconductor region quickly, reducing the resistance of the drift region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the connection semiconductor region is formed only at a part of the side surface of the trench, then the device complexity is reduced and manufacturing is simplified, but the resistance of the drift region is not easily lowered due to delayed depletion layer contraction, resulting in high loss
Solution Approach 1:
The patent introduces a conductor layer at the bottom of the trench, extending in the longitudinal direction, to provide a new charge supply path from the bottom upward. This three-dimensional charge supply architecture complements the side surface connection, enabling rapid charge distribution to distant bottom semiconductor region portions without increasing side surface complexity.
Solution Approach 2:
The conductor layer acts as an intermediary between the connection semiconductor region and the bottom semiconductor region. It receives charges from the connection semiconductor region and rapidly distributes them along the trench bottom to distant portions, mediating the charge transfer and eliminating the resistance issue without requiring extended connection semiconductor regions.
2Speed
If charges are supplied from the connection semiconductor region to the bottom semiconductor region over a long distance, then the depletion layer contraction is delayed, but increasing the connection semiconductor region coverage increases device complexity
Solution Approach 1:
The patent transitions from a side-surface-only charge supply path to a bottom-up charge supply path via the conductor layer. This longitudinal extension at the trench bottom provides rapid charge distribution to distant portions without requiring expanded side surface coverage, maintaining structural simplicity while improving charge supply speed.
Solution Approach 2:
The charge supply function is segmented between the connection semiconductor region (at the side surface) and the conductor layer (at the bottom). The connection semiconductor region provides localized charge injection, while the conductor layer distributes charges rapidly along the trench bottom, dividing the long-distance charge transfer into shorter, faster segments.
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 enables rapid contraction of the depletion layer around the entire bottom semiconductor region, significantly reducing on-resistance and loss when the switching device is turned on.
Implementation Method 1
the conductor layer is formed by alloying a metal layer with the trench bottom
Implementation Method 2
When the charges are supplied to the bottom semiconductor region, the depletion layer extending from the bottom semiconductor region into the drift region contracts toward the bottom semiconductor region. Therefore, the resistance of the drift region is reduced
Data Source
AI summary
A switching device includes a semiconductor substrate; a trench; a conductor layer extending in a longitudinal direction of the trench so as to be in contact with a bottom surface of the trench; a bottom insulating layer covering an upper surface of the conductor layer; a gate insulating layer covering a side surface of the trench; and a gate electrode disposed in the trench. The semiconductor substrate includes a first semiconductor region of a first conductivity type, a body region of a second conductivity type, a second semiconductor region of the first conductivity type, a bottom semiconductor region of the second conductivity type extending in the longitudinal direction so as to be in contact with the conductor layer, and a connection semiconductor region of the second conductivity type connected to the body region and to the bottom semiconductor region.