Vertical FET Pad Layout for Low On-Resistance and Heat Control
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Solution Overview
Problem
Existing chip-size-package type vertical field-effect transistors face challenges in efficiently passing heavy currents without increasing on-resistance and minimizing local heat generation due to limited chip area utilization.
Innovation Solution
A semiconductor device with a facedown mountable, chip-size-package configuration, featuring a vertical field-effect transistor and drain lead-out region in a semiconductor layer, where the placement of source and drain pads is optimized to reduce on-resistance and heat generation by utilizing the entire chip area effectively, with source pads in rectangular or obround shapes and drain pads in matching shapes, disposed in stripes with uniform spacing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the chip area is increased to reduce on-resistance and pass heavy current, then the current handling capability is improved, but the device size increases which is not acceptable for chip-size-package applications
Solution Approach 1:
The patent transitions from planar pad arrangements to a three-dimensional vertical structure by stacking source pads, drain pads, and gate pads in multiple layers. This vertical stacking enables heavy current handling equivalent to larger chip areas while maintaining a compact footprint, effectively resolving the contradiction between current capacity and chip size.
Solution Approach 2:
The patent divides the pad structure into multiple discrete layers (first source pad layer, first drain pad layer, second source pad layer, second drain pad layer) with intermediate regions in between. This segmentation allows optimized current distribution across layers, reducing on-resistance without requiring a larger overall chip area.
2Reliability
If current density is increased to pass heavy current through limited area, then the current handling is improved, but local heat generation increases
Solution Approach 1:
By segmenting the current path into multiple parallel layers with intermediate regions, the patent distributes current density across a larger effective volume. This reduces peak current density in any single location, thereby minimizing localized heat generation while maintaining overall heavy current handling capability.
Solution Approach 2:
The intermediate regions between the first and second source/drain pad layers act as mediators that facilitate heat dissipation and current distribution. These regions provide thermal pathways and electrical connections that balance current flow, preventing excessive heat concentration in critical areas.
3Reliability
If the pad placement is optimized to reduce on-resistance, then the electrical performance is improved, but the manufacturing complexity increases
Solution Approach 1:
The multi-layer pad structure is divided into discrete, standardized layers (first source pad layer, first drain pad layer, second source pad layer, second drain pad layer) with clear spatial relationships. This segmentation transforms a complex optimization problem into a systematic layer-by-layer fabrication process, improving electrical performance while managing manufacturing complexity through modular construction.
Data Source
AI summary
A semiconductor device includes: a semiconductor layer in a rectangular shape in a plan view; a transistor provided in a first region; and a drain lead-out region provided in a second region. A border line is a straight line parallel to longer sides of the semiconductor layer. The first region includes a plurality of source pads and gate pads. The second region includes a plurality of drain pads. One gate pad among the gate pads is disposed to dispose none of the plurality of source pads between (i) the one gate pad and (ii) one longer side and one shorter side. One drain pad among the plurality of drain pads is in the same shape as the one gate pad and is disposed close to a second vertex. The plurality of source pads include a source pad that is in a rectangular shape or an obround shape having a longitudinal direction parallel to the longer sides of the semiconductor layer.