Source-Surrounding Gate Structure for HEMT Leakage Suppression
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Solution Overview
Problem
High-voltage transistor devices, particularly HEMT devices, experience unwanted leakage currents due to incomplete isolation, leading to sub-threshold humps in drain current vs. gate voltage characteristics, increased power consumption, and modeling difficulties.
Innovation Solution
The integration of a gate structure that wraps around the source contact to disrupt the underlying 2DEG, thereby reducing leakage currents. This gate structure extends along one side of the source contact and wraps around its opposing ends, creating a continuous path to enclose the source contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional gate structure is used in high-voltage transistor devices, then the device can handle high breakdown voltages and high frequencies, but unwanted leakage currents occur due to incomplete isolation
Solution Approach 1:
The gate structure is extended from a conventional planar configuration into the third dimension by wrapping around the source contact. This three-dimensional configuration creates a continuous isolation barrier that completely surrounds the source contact, eliminating leakage paths that exist in conventional two-dimensional gate structures.
Solution Approach 2:
The gate structure is divided into multiple segments: a first gate portion extending along one side of the source contact, and second gate portions wrapping around opposing ends of the source contact. These segmented portions work together to form a complete isolation barrier, allowing the gate to effectively block leakage currents from multiple directions.
2Loss of energy
If the gate structure wraps around the source contact to improve isolation, then leakage currents are reduced, but the device structure becomes more complex
Solution Approach 1:
The wrapped gate structure serves multiple functions simultaneously: it provides electrical isolation between source and drain, controls the channel current, and eliminates sub-threshold humps in the current-voltage characteristics. This multi-functionality reduces the need for additional separate structures, thereby managing complexity while achieving multiple goals.
3Reliability
If isolation is improved by wrapping the gate around the source contact, then sub-threshold humps are eliminated, but manufacturing precision requirements increase
Solution Approach 1:
The gate structure is designed and formed with predetermined dimensions and positions that ensure proper wrapping around the source contact before subsequent manufacturing steps. The gate portions are configured to extend along and wrap around the source contact in a controlled manner, establishing the isolation geometry early in the manufacturing process and reducing alignment challenges in later steps.
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 solution effectively reduces leakage currents between the source and drain contacts, minimizing power consumption and simplifying device modeling by eliminating sub-threshold humps in current-voltage characteristics.
Implementation Method 1
disrupt the underlying 2DEG, thereby reducing leakage currents
Data Source
AI summary
In some embodiments, the present disclosure relates to a method of forming a transistor device. The method includes forming a source contact over a substrate, forming a drain contact over the substrate, and forming a gate contact material over the substrate. The gate contact material is patterned to define a gate structure that wraps around the source contact along a continuous and unbroken path.