HEMT Electrode Structure With Vertical Extension for Higher Breakdown Voltage
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Solution Overview
Problem
Conventional high electron mobility transistors (HEMTs) face a limitation in breakdown voltage, which hinders their ability to meet industry requirements for high power and frequency applications.
Innovation Solution
A semiconductor device structure is developed, featuring a substrate, semiconductor channel layer, semiconductor barrier layer, gate electrode, and dielectric layer, with a first electrode having a body portion and a vertical extension portion, where the bottom surface of the vertical extension portion is lower than the top surface of the semiconductor channel layer, and a dielectric layer is disposed between the vertical extension portion and the semiconductor channel layer, enhancing breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional HEMT structure is used, then device simplicity is maintained, but breakdown voltage is insufficient
Solution Approach 1:
The first electrode is segmented into a body portion and a vertical extension portion. The vertical extension portion extends downward from the body portion into the dielectric layer, creating a segmented structure that reduces peak electric field intensity at the electrode-channel layer interface while maintaining electrical connection to the semiconductor barrier layer through the body portion.
Solution Approach 2:
A dielectric layer is introduced as an intermediary between the vertical extension portion of the first electrode and the semiconductor channel layer. This dielectric layer acts as a mediator that reduces direct electric field interaction between the electrode and the channel layer, thereby reducing impact ionization rates and improving breakdown voltage.
2Ease of manufacture
If electrode structure is simplified, then manufacturing is easier, but peak electric field intensity increases
Solution Approach 1:
The electrode structure transitions from a conventional planar configuration to a three-dimensional structure with a vertical extension portion. This dimensional change allows the electrode to extend into the dielectric layer without significantly complicating the fabrication process, effectively reducing peak electric field intensity at the interface while maintaining ease of manufacture through standard deposition and etching techniques.
3Reliability
If conventional structure is used, then device complexity is low, but impact ionization rate is high
Solution Approach 1:
The dielectric layer serves as an intermediary substance between the vertical extension portion of the first electrode and the semiconductor channel layer. This intermediary layer reduces direct interaction between high electric fields and the channel layer, thereby reducing impact ionization rates while the integration process remains compatible with standard semiconductor manufacturing techniques.
Solution Approach 2:
The dielectric layer is a relatively simple material layer that can be deposited using standard techniques and serves its protective and field-reducing function effectively. While it adds a processing step, the material itself is inexpensive and the added complexity is minimal compared to the significant improvement in impact ionization resistance.
Data Source
AI summary
A semiconductor device includes a substrate, a semiconductor channel layer, a semiconductor barrier layer, a gate electrode, a first electrode, and a dielectric layer. The semiconductor channel layer is disposed on the substrate, and the semiconductor barrier layer is disposed on the semiconductor channel layer. The gate electrode is disposed on the semiconductor barrier layer. The first electrode is disposed at one side of the gate electrode. The first electrode includes a body portion and a vertical extension portion. The body portion is electrically connected to the semiconductor barrier layer, and the bottom surface of the vertical extension portion is lower than the top surface of the semiconductor channel layer. The dielectric layer is disposed between the vertical extension portion and the semiconductor channel layer. The first electrode is a conformal layer covers the semiconductor barrier layer and the dielectric layer.