Nitride Semiconductor Device Recessed Gate Structure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for manufacturing nitride semiconductor devices with a group III nitride semiconductor face challenges in achieving normally-off operation due to issues with current flow, gate leakage current, and control over threshold voltage and forward voltage, leading to poor in-plane distribution and controllability.
Innovation Solution
A nitride semiconductor device structure featuring a substrate with a first nitride semiconductor layer, a second layer with a larger band gap covering a recess in the first layer, and a third layer continuously covering the second layer and the recess, along with a gate electrode and ohmic electrodes, allows for improved control over threshold voltage and forward voltage through precise in-plane distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the carrier supply layer is made thin to achieve normally-off operation, then the threshold voltage control is improved, but the gate leakage current increases and manufacturing precision deteriorates
Solution Approach 1:
The carrier supply layer is divided into two distinct layers: a first carrier supply layer (AlGaN) and a second carrier supply layer (GaN). This segmentation allows the first layer to provide carriers while the second layer acts as a barrier to gate leakage current, resolving the contradiction between achieving normally-off operation and reducing gate leakage.
Solution Approach 2:
The second carrier supply layer (GaN layer) serves as an intermediary between the first carrier supply layer and the gate electrode. It mediates the conflict by blocking gate leakage current while still allowing the structure to maintain normally-off operation through the combined effect of both layers.
2Manufacturing precision
If the carrier supply layer thickness is reduced to control threshold voltage, then normally-off operation is achieved, but in-plane distribution uniformity deteriorates
Solution Approach 1:
By segmenting the carrier supply layer into two layers with different materials and thicknesses, the invention achieves uniform in-plane distribution. The first layer (AlGaN) provides consistent carrier supply across the plane, while the second layer (GaN) ensures uniform threshold voltage control, together improving both controllability and uniformity.
Solution Approach 2:
Different regions of the semiconductor structure have different layer configurations optimized for their specific functions. The first carrier supply layer has uniform thickness for consistent carrier supply, while the second carrier supply layer provides localized threshold voltage control, achieving both uniformity and controllability.
3Manufacturing precision
If a recessed structure is formed to shift threshold voltage positively, then normally-off operation is achieved, but manufacturing complexity increases
Solution Approach 1:
Instead of forming a recessed structure to achieve normally-off operation, the invention inverts the approach by stacking two carrier supply layers in a planar configuration. This inversion simplifies the manufacturing process while achieving the same electrical effect of positive threshold voltage shift and normally-off operation.
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 proposed structure significantly enhances the controllability and in-plane distribution of the threshold voltage, reducing gate leakage current and enabling reliable normally-off operation.
Implementation Method 1
a second nitride semiconductor layer located over a portion of the first nitride semiconductor layer other than the recess, and having a larger band gap than the first nitride semiconductor layer
Data Source
AI summary
A nitride semiconductor device includes: a substrate; a first nitride semiconductor layer (1) located over the substrate; a second nitride semiconductor layer (2) located over the first nitride semiconductor layer (1), having a larger band gap than the first nitride semiconductor layer (1), and having a recess (11) penetrating into the first nitride semiconductor layer (1); and a third nitride semiconductor layer (12) continuously covering the second nitride semiconductor layer (2) and the recess (11), and having a larger band gap than the first nitride semiconductor layer (1); a gate electrode (5) located above a portion of the third nitride semiconductor layer (12) over the recess (11); and a first ohmic electrode (4a) and a second ohmic electrode (4b) located on opposite sides of the gate electrode (5).