HEMT Field Plate Segmentation for High-dV/dt Switching Response
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Solution Overview
Problem
High-electron-mobility transistors (HEMTs), particularly GaN power HEMTs, face challenges in optimizing gate to drain spacing due to the distributed RC effect caused by field plates, especially under high frequency and high dvdt switching environments, which affects their performance.
Innovation Solution
A semiconductor structure is designed with a field plate electrically isolated from the gate structure and abutting the source and drain contacts, surrounded by a sidewall spacer, and optionally separated from the source and drain regions by a passivation layer, to reduce field crowding and improve switching response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If field plates are used to reduce gate to drain spacing, then device optimization is improved, but distributed RC effect increases under high frequency high dvdt switching environments
Solution Approach 1:
The field plate is segmented into multiple isolated field plates positioned along the drain region, with each field plate electrically isolated from the gate structure. This segmentation reduces the distributed RC effect by breaking up the continuous capacitive coupling while maintaining field control for optimized gate-to-drain spacing.
Solution Approach 2:
An insulating layer is introduced as an intermediary between the field plate and the gate structure, preventing direct electrical connection. This intermediary layer eliminates the parasitic capacitance between the field plate and gate while allowing the field plate to maintain its field control function for reduced gate-to-drain spacing.
2Manufacturing precision
If field plate contacts source and drain contacts directly, then field control is improved, but field crowding increases at the drain region
Solution Approach 1:
The field plate is positioned to provide localized field control specifically at the drain region where field crowding occurs, rather than uniform control across the entire device. This localized approach addresses the field crowding problem at the critical drain area while maintaining overall field control where needed.
Solution Approach 2:
The field plate is biased to create an equipotential region that extends into the drain area, reducing field crowding by distributing the electric field more uniformly. This equipotential structure prevents excessive field concentration at the drain edge while maintaining effective field control for device operation.
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to a high-electron-mobility transistor (HEMT) and methods of manufacture. The structure includes: a gate structure; a source contact and a drain contact adjacent to the gate structure; and a field plate electrically isolated from the gate structure and abutting the source contact and the drain contact.