Nitride Semiconductor Gate Structure for Lower Gate-Source Capacitance
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Solution Overview
Problem
Nitride semiconductor devices face challenges in reducing gate-source capacitance while preventing self-turn-on phenomena and shoot-through current, which can lead to inefficiencies in high-speed switching and increased switching loss.
Innovation Solution
The nitride semiconductor device incorporates an insulation layer with a specific thickness ratio and a spacer layer to decrease gate-source capacitance, comprising a passivation layer and a spacer layer, which increases the distance between the gate and source electrodes, thereby controlling the input capacitance and total gate charge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the distance between gate and source electrodes is reduced to decrease gate-source capacitance, then switching speed is improved, but self-turn-on phenomena and shoot-through current occur
Solution Approach 1:
An insulation layer is introduced as an intermediary between the gate electrode and source electrode. This insulation layer physically separates the two electrodes, preventing direct electrical contact that causes self-turn-on and shoot-through current, while still allowing the device to achieve fast switching performance through optimized electrode geometry and material properties.
Solution Approach 2:
The patent optimizes the thickness and material properties of the insulation layer, as well as the geometric parameters of the gate and source electrodes, to achieve the right balance between minimizing capacitance (for fast switching) and preventing harmful electrical phenomena. By carefully controlling these parameters, the device achieves high-speed switching without self-turn-on or shoot-through current.
2Speed
If the gate-source capacitance is reduced for high-speed switching, then switching performance is improved, but switching loss increases
Solution Approach 1:
The patent optimizes multiple parameters simultaneously: the insulation layer thickness, electrode dimensions, and material properties. By carefully balancing these parameters, the device achieves low gate-source capacitance for fast switching while minimizing the energy loss associated with charging and discharging the capacitance during switching operations.
Solution Approach 2:
The patent employs composite structures combining different materials with complementary properties - the insulation layer material is selected for its dielectric properties that minimize capacitance while the electrode materials are chosen for their conductivity and compatibility with the insulation layer, achieving both fast switching and low loss.
Data Source
AI summary
A nitride semiconductor device includes an electron transit layer, an electron supply layer, a gate layer, a gate electrode, an insulation layer covering the electron supply layer, the gate layer, and the gate electrode and including a first opening and a second opening, a source electrode, and a drain electrode. The source electrode includes a source field plate covering the insulation layer and including an end located between the second opening and the gate layer in plan view. The insulation layer includes a first insulation layer part and a second insulation layer part. The first insulation layer part is disposed on the electron supply layer in contact with the drain electrode and has a first thickness. The second insulation layer part is disposed on the gate electrode in contact with the source field plate and has a second thickness. The second thickness is greater than the first thickness.