Semiconductor Device With Segmented Field Plate
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Solution Overview
Problem
Conventional LD-MOSFETs have high total gate-to-drain capacitance, limiting their switching speed and preventing them from functioning well in high-frequency applications.
Innovation Solution
The semiconductor device incorporates a first field-plate conductor separated from the gate-electrode layer by a gap, with a second field-plate conductor covering the first field-plate conductor and the gap, reducing the overlapping area between the gate and drain regions and minimizing gate-to-drain capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the gate-to-drain overlapping area is reduced to lower parasitic capacitance, then the switching speed improves, but the voltage handling capability and breakdown voltage performance deteriorate
Solution Approach 1:
The field plate structure is segmented into multiple conductive regions (first field plate conductor and second field plate conductor) separated by a gap. This segmentation allows the field plate to extend laterally without directly overlapping the gate electrode, thereby reducing gate-to-drain capacitance while maintaining voltage handling capability through the distributed field control provided by the segmented structure
Solution Approach 2:
A dielectric material is introduced as an intermediary substance filling the gap between the first and second field plate conductors. This dielectric mediator enables the field plate to maintain electrical isolation from the gate electrode while still providing field control, thus reducing parasitic capacitance without sacrificing breakdown voltage performance
2Speed
If the gate-to-drain overlapping area is reduced to lower parasitic capacitance, then the switching speed improves, but the device complexity increases
Solution Approach 1:
The field plate structure serves multiple functions simultaneously: it extends the gate control region laterally to improve voltage handling, reduces gate-to-drain overlapping area to lower parasitic capacitance, and the dielectric-filled gap provides both electrical isolation and mechanical support. This multi-functionality reduces the need for additional separate structures, thereby managing device complexity while achieving performance improvements
Data Source
AI summary
A semiconductor device including a substrate having a drain region therein is provided. A gate-electrode layer is disposed on the drain region. A first field-plate conductor is disposed on the substrate and overlaps the drain region. A gap is located laterally between the first field-plate conductor and the gate-electrode layer. A second field-plate conductor covers the first field-plate conductor and the gap. The second field-plate conductor is separated from the first field-plate conductor. A method for forming the semiconductor device is also provided.