Nitride Gate Structure With Source Insulator for Low-Leakage Operation
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Solution Overview
Problem
Current nitride semiconductor devices face challenges in achieving normal disconnection and stable operation due to the formation of two-dimensional electron gas (2DEG) under the gate layer, leading to issues with gate leakage current and on-resistance.
Innovation Solution
The nitride semiconductor device incorporates a gate layer with acceptor-type impurities, forming a stepped structure with ridge and extension portions, and a passivation layer with different materials for the first and second passivation layers, along with a source and drain insulator film to block leakage paths and reduce on-resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gate layer is provided directly below the gate electrode on the electron travelling layer to achieve normal disconnection by increasing band energy, then gate disconnection is achieved, but gate leakage current increases and on-resistance increases
Solution Approach 1:
The gate layer is designed with non-uniform thickness, having a first thickness in the first region and a second thickness (different from the first) in the second region. This local variation in thickness creates different electrical characteristics in different regions, allowing the gate to achieve normal disconnection in one region while minimizing leakage current in another region.
Solution Approach 2:
The solution moves from a uniform two-dimensional gate structure to a three-dimensional structure with variable thickness. By introducing the thickness dimension variation, the gate layer can simultaneously provide high band energy for disconnection in the first region and lower resistance path in the second region, resolving the contradiction between disconnection reliability and leakage current.
2Reliability
If the gate layer increases band energy of the conduction band near the heterojunction interface to make the channel disappear, then normal disconnection is achieved, but on-resistance increases
Solution Approach 1:
The gate layer has different thicknesses in different regions, creating local variations in electrical properties. The first region with one thickness provides the band energy increase for normal disconnection, while the second region with different thickness maintains lower on-resistance, thus resolving the contradiction between disconnection reliability and energy loss.
3Loss of energy
If source and drain electrodes are placed closer to reduce on-resistance, then on-resistance decreases, but electrical leakage paths increase
Solution Approach 1:
The gate layer's variable thickness creates different electrical characteristics in different spatial regions. This allows source and drain electrodes to be positioned closer together (reducing on-resistance) while the gate layer's structural variations prevent electrical leakage paths from forming between the closely spaced electrodes.
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
This configuration effectively suppresses gate leakage current, improves gate withstand voltage, and reduces on-resistance by blocking electrical leakage paths and allowing for closer placement of source and drain electrodes, enhancing the device's operational stability and efficiency.
Implementation Method 1
the gate layer will increase the band energy of the conduction band near the heterojunction interface between the electron travelling layer and the electron supply layer, so that the channel directly below the gate layer will disappear
Implementation Method 2
forming a source insulator film insulating the gate layer from the source electrode... the source insulator film blocks leakage paths and reduce on-resistance
Data Source
AI summary
The present disclosure provides a nitride semiconductor device. The nitride semiconductor device includes an electron travelling layer, an electron supply layer, a gate layer, a gate electrode, a source electrode, a drain electrode and a passivation layer. The gate layer includes a gate layer side surface located at an end portion of a side of the source electrode along a first direction, which is a direction in which the gate layer, the source electrode and the drain electrode are arranged. The passivation layer includes a passivation first side surface facing the source electrode along the first direction. The nitride semiconductor device further includes a source insulator film that covers the gate layer side surface and the passivation first side surface. The source insulator film insulates the gate layer from the source electrode.