Dual Isolation Structure for HEMT Gate Leakage and Signal Control
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Solution Overview
Problem
Conventional HEMT devices face challenges with electrical isolation between devices, leading to signal distortions and limited gate length due to mesa etch regions, which restricts performance in high-frequency applications.
Innovation Solution
A dual isolation structure is implemented around the HEMT device, using doped semiconductor material on opposing sides of the channel material, with the gate metal not extending beyond the isolation structure edges, ensuring coplanarity and preventing signal overlap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mesa etch is used to isolate devices, then electrical isolation between devices is achieved, but gate length is limited to approximately 0.2 μm due to overlap with mesa etch region
Solution Approach 1:
The isolation structure is divided into two distinct segments: a first isolation structure formed in the first semiconductor layer and a second isolation structure formed in the second semiconductor layer. This segmentation allows each isolation structure to perform its isolation function independently at different depths, enabling complete electrical isolation without requiring the gate to be shortened to avoid mesa etch overlap.
Solution Approach 2:
The solution transitions from a single-plane isolation approach to a multi-layer isolation approach by forming isolation structures in both the first and second semiconductor layers. This vertical dimensionality change allows the gate to extend fully in the horizontal direction without overlapping with isolation regions, thereby achieving both complete electrical isolation and maximum gate length.
2Reliability
If a mesa etch is used for device isolation, then devices are isolated, but signal distortions occur due to gate overlap with mesa etch region
Solution Approach 1:
By segmenting the isolation into two separate structures at different vertical levels, the gate can be positioned between them without overlapping either isolation region. This eliminates the source of signal distortions while maintaining effective device isolation through the combined action of both isolation structures.
Solution Approach 2:
The second isolation structure acts as an intermediary element that bridges the gap between the first isolation structure and the gate. This intermediate isolation layer prevents direct interaction between the gate and the first isolation structure, eliminating signal distortions while maintaining electrical isolation.
3Reliability
If a dual isolation structure is implemented, then gate-drain leakage is reduced and yield is improved, but device complexity increases
Solution Approach 1:
The dual isolation structure segments the isolation function into two distinct layers, with each layer contributing to gate-drain leakage reduction. This segmentation provides superior electrical isolation and yield improvement compared to single-layer isolation, while the modular nature of the segmented structure facilitates integration into existing semiconductor manufacturing processes.
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 dual isolation structure reduces gate-drain leakage and allows for increased yield and improved performance without short gate lengths, minimizing signal distortions and enhancing high-frequency operation.
Implementation Method 1
forming a first isolation structure of doped semiconductor material on a first side of the channel material of the active device region; and forming a second isolation structure of the doped semiconductor material on a second, opposing side of the channel material
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to a semiconductor device with a dual isolation structure and methods of manufacture. The structure includes: a dual isolation structure including semiconductor material; and an active device region including a channel material and a gate metal material over the channel material. The channel material is between the dual isolation structure and the gate metal material includes a bottom surface not extending beyond a sidewall of the dual isolation structure.