Semiconductor Device With Trench Protrusions For Current Density
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Solution Overview
Problem
Semiconductor devices for electric power require low on-resistance and high breakdown voltage, but increasing the epitaxial layer concentration and thickness to achieve these characteristics increases on-resistance and reduces forward current density.
Innovation Solution
The semiconductor device includes a substrate with an n− type layer, trenches with protruded parts, and specific region structures that increase the channel length and density, allowing for improved forward current density without adjusting the epitaxial layer or drift region characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the epitaxial layer concentration and thickness are increased to achieve low on-resistance and high breakdown voltage, then the breakdown voltage characteristic is improved, but the on-resistance increases and forward current density decreases
Solution Approach 1:
The patent divides the channel region into multiple segments by introducing trenches with protruded parts. This segmentation increases the effective channel length and channel density without requiring increased epitaxial layer thickness, thereby maintaining forward current density while achieving high breakdown voltage through the segmented structure that optimizes electric field distribution.
Solution Approach 2:
The patent transitions from a planar channel structure to a three-dimensional structure by adding protruded parts that extend in the vertical dimension. This dimensional change increases the channel density and effective channel length without increasing the epitaxial layer thickness, resolving the contradiction between breakdown voltage and forward current density.
2Reliability
If the epitaxial layer thickness is increased to improve breakdown voltage, then the high breakdown voltage characteristic is achieved, but the device area increases and manufacturing cost increases
Solution Approach 1:
By segmenting the channel region with trenches containing protruded parts, the patent achieves high breakdown voltage through optimized electric field distribution in the vertical direction without requiring increased epitaxial layer thickness. This maintains a compact device footprint while achieving the desired voltage blocking capability.
Solution Approach 2:
The patent changes the structural parameters of the channel region by introducing protruded parts with specific dimensions (width of 0.5-2.0 μm, spacing of 0.5-2.0 μm). These parameter changes increase channel density and effective channel length, enabling high breakdown voltage in a compact area without increasing epitaxial layer thickness.
3Productivity
If the channel length is increased to improve forward current density, then the forward current density increases, but the device area increases
Solution Approach 1:
The patent utilizes the vertical dimension by adding protruded parts that extend upward from the trench bottoms. This three-dimensional structure increases the effective channel length and channel density without expanding the planar device footprint, thereby increasing forward current density while maintaining a compact area.
Solution Approach 2:
The protruded parts are nested within the trench structures, creating a compact configuration where the channel-forming regions are embedded within the trench boundaries. This nesting approach increases channel density without proportionally increasing the overall device area, as the protruded parts utilize the vertical space within the trench structure.
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
This design enhances channel density and forward current density, reducing power loss and production costs while maintaining high breakdown voltage, thereby improving the efficiency and yield of semiconductor devices.
Implementation Method 1
According to Poisson's equation, as the high breakdown voltage of the power semiconductor device is required, the epitaxial layer or the drift region of a low concentration and a thick thickness are needed
Data Source
AI summary
A semiconductor device according to an exemplary embodiment of the present disclosure includes a substrate, an n− type layer, a plurality of trenches, a p type region, a p+ type region, an n+ type region, a gate electrode, a source electrode, and a drain electrode. The semiconductor device may include a plurality of unit cells. A unit cell among the plurality of unit cells may include a contact portion with which the source electrode and the n+ type region are in contact, a first branch part disposed above the contact portion on a plane, and a second branch part disposed below the contact portion on a plane, the plurality of trenches are separated from each other and disposed with a stripe shape on a plane.