Semiconductor Device Field Plate Gate-Source Capacitance
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Solution Overview
Problem
High electron mobility transistors (HEMTs) face challenges in achieving high breakdown voltage and efficient high-frequency operation due to limitations in gate-source capacitance and electric field distribution, which affect the Miller ratio and shoot-through current.
Innovation Solution
A semiconductor device design featuring a substrate, active layer, source and drain electrodes, a gate electrode, field plate, passivation layers, and a metal layer, where the field plate is positioned between the gate and drain electrodes, and the metal layer is electrically connected to the source electrode, optimizing the distances and connections to enhance gate-source capacitance and electric field distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the gate electrode is positioned close to the active layer to reduce device size, then the device area is reduced, but the breakdown voltage decreases due to increased electric field intensity
Solution Approach 1:
A field plate is introduced as an intermediary conductive structure positioned between the gate electrode and the drain electrode. The field plate serves as a mediator that redistributes the electric field in the drain region, reducing peak electric field intensity near the gate while maintaining compact device dimensions. This intermediary structure enables the device to achieve both small area and high breakdown voltage.
2Productivity
If the gate-source capacitance is increased to improve high-frequency operation, then the Miller ratio is reduced, but the device complexity increases
Solution Approach 1:
The field plate is electrically connected to either the gate electrode or the source electrode, merging its function with existing device components. This integration allows the field plate to contribute to gate-source capacitance enhancement without requiring completely separate control circuitry, thereby improving high-frequency operation while limiting the increase in device complexity.
3Reliability
If the field plate is positioned close to the active layer to enhance electric field control, then the electric field distribution is improved, but the risk of electric field concentration and breakdown increases
Solution Approach 1:
The field plate is positioned specifically in the drain region where electric field control is most critical for breakdown voltage enhancement. By concentrating the field plate structure locally in the drain area rather than uniformly across the device, the invention achieves improved electric field control where needed while avoiding excessive electric field concentration in other regions, thus preventing breakdown.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design increases the breakdown voltage and reduces the Miller ratio, facilitating high-frequency operations while minimizing shoot-through current by effectively managing the electric field and capacitance, as demonstrated by improved gate-source charge and Miller ratio values.
Implementation Method 1
optimizing the distances and connections to enhance gate-source capacitance and electric field distribution
Implementation Method 2
enhance gate-source capacitance and electric field distribution
Data Source
AI summary
A semiconductor device includes a substrate, an active layer, a source electrode, a drain electrode, a gate electrode, a field plate, a first passivation layer, and a metal layer. The active layer is disposed on the substrate. The source electrode and the drain electrode are respectively electrically connected to the active layer. The gate electrode is disposed between the source electrode and the drain electrode and above the active layer. The field plate is disposed above the active layer and between the gate electrode and the drain electrode. The first passivation layer covers the gate electrode and the field plate. The metal layer is disposed on the first passivation layer, is disposed above the gate electrode and the field plate, and is electrically connected to the source electrode.