HEMT Field Plate Layout for High Drain Bias Stability
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Solution Overview
Problem
Conventional high-electron mobility transistors (HEMTs) face premature collapse under high drain biases and surface defects on the gate electrode, affecting dynamic on-resistance.
Innovation Solution
The design includes a substrate with an active region, a gate electrode, drain and source electrodes, and a first field plate electrically connected to the source electrode, extending towards the drain electrode. The overlapping area of the first field plate and the gate electrode is smaller than the overlapping area of the gate electrode and the active region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional HEMT structure is used, then high electron mobility is achieved, but premature collapse occurs under high drain biases
Solution Approach 1:
A field plate structure is introduced as an intermediary component between the gate electrode and the drain region. The field plate extends from the gate electrode toward the drain electrode, creating a gradual electric field transition zone that mediates the high drain bias stress, preventing direct stress concentration on the gate electrode and active region interface.
Solution Approach 2:
The field plate extends in the lateral dimension from the gate electrode toward the drain electrode, creating an additional spatial dimension for electric field management. This lateral extension allows the electric field to be distributed over a larger area, reducing field concentration at critical interfaces and preventing premature collapse.
2Speed
If conventional HEMT structure is used, then high frequency transmission capability is achieved, but surface defects form on the gate electrode during switching
Solution Approach 1:
The field plate is positioned beforehand to provide protective coverage over the gate electrode surface during switching operations. This pre-positioned structure acts as a cushioning element that prevents direct exposure of the gate electrode surface to high electric field stress and plasma damage during the switching process, thereby preventing surface defect formation.
3Reliability
If field plate overlapping area with gate electrode is increased, then electric field control is improved, but parasitic capacitance increases affecting switching speed
Solution Approach 1:
The field plate is designed with non-uniform overlapping characteristics - it extends laterally from the gate electrode toward the drain electrode but with controlled overlap. The overlapping area is intentionally kept smaller than the gate electrode-active region overlap, creating local quality variation that provides sufficient electric field control in critical regions while minimizing parasitic capacitance in other areas.
Data Source
AI summary
A high-electron mobility transistor includes a substrate, a gate electrode, a drain electrode, a source electrode and a first field plate. The substrate includes an active region. The gate electrode is disposed on the substrate. The drain electrode is disposed at one side of the gate electrode. The source electrode is disposed at another side of the gate electrode. The first field plate is electrically connected with the source electrode and extends from the source electrode toward the drain electrode. An overlapping area of the first field plate and the gate electrode is smaller than an overlapping area of the gate electrode and the active region.