MOSFET Trench Gate Segmentation for Low Parasitic Capacitance
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Solution Overview
Problem
MOSFETs face trade-offs in optimizing device parameters such as on-resistance (RDSON) and breakdown voltage (BVDSS), where improvements in one parameter often degrade others, like increasing parasitic capacitance.
Innovation Solution
The formation of a trench and conductive structure within a semiconductor device, including a vertically-oriented conductive region and a horizontally-oriented doped region, allows for improved charge carrier flow directionality, reducing parasitic capacitance and maintaining low RDSON while enhancing breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional MOSFET structures are used to improve on-resistance (RDSON), then RDSON decreases, but parasitic capacitance increases and breakdown voltage (BVDSS) decreases
Solution Approach 1:
The patent segments the drain region into multiple discrete drain contacts separated by isolation trenches, rather than using a single large drain contact. This segmentation reduces the overlap area between the drain and gate, thereby reducing parasitic capacitance while maintaining low on-resistance through multiple parallel current paths
Solution Approach 2:
The patent introduces vertical isolation trenches that extend into the substrate, adding a vertical dimension to the isolation strategy. This vertical segmentation effectively reduces the lateral overlap between conductive regions, reducing parasitic capacitance without increasing the planar footprint
Data Source
AI summary
A process of forming an electronic device can include providing a workpiece comprising a substrate, including an underlying doped region, and a semiconductor layer overlying the underlying doped region, wherein the semiconductor layer has a primary surface spaced apart from the underlying doped region. The process can also include forming a vertically-oriented conductive region extending from the primary surface to the underlying doped region, and forming a horizontally-oriented doped region adjacent to the primary surface. In a finished form of the electronic device, the horizontally-oriented doped region extends further in a lateral direction toward a region where a source region has been or will be formed, as compared to the vertically-oriented conductive region. The electronic device includes a transistor that includes the underlying doped region, the vertically-oriented conductive region, and the horizontally-oriented doped region.