Selective Etch Recess Formation in III-Nitride Power Transistors
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Solution Overview
Problem
Conventional power transistors made of silicon are unsuitable for future applications due to their limited critical electric field and high resistance, leading to large and heavy devices operating at low frequencies, while nitride semiconductor devices offer potential for high-efficiency power electronics but face challenges with plasma-induced damage and precise etch depth control in recess formation.
Innovation Solution
The development of semiconductor structures and processes that utilize selective dry and wet etching techniques to form recesses in III-Nitride semiconductor materials, allowing for precise control of etch depth and reducing defect density, enabling the fabrication of high-performance transistors with reduced plasma damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional silicon-based transistors are used, then manufacturing maturity is high, but critical electric field is limited and resistance is high
Solution Approach 1:
The patent transitions from silicon-based to nitride semiconductor materials, fundamentally changing the material parameter to achieve higher critical electric field and lower resistance. This material parameter change enables high-voltage blocking capability while maintaining compact device dimensions suitable for modern power electronics applications.
Solution Approach 2:
The invention employs composite nitride semiconductor structures with multiple layers including AlGaN barrier layers and GaN channel layers. This composite material approach optimizes both the critical electric field for high-voltage blocking and the manufacturing processability through selective etching characteristics of different nitride material compositions.
2Reliability
If nitride semiconductor devices are used, then critical electric field and resistance performance improve, but plasma-induced damage and etch depth control become problematic
Solution Approach 1:
The patent segments the barrier layer into two distinct layers with different etch selectivity: a first layer that is highly selective to the etching plasma and a second layer that is less selective. This segmentation enables precise etch depth control by using the first layer as a sacrificial layer that can be selectively removed to expose the second layer at a controlled depth, thereby preventing over-etching and plasma-induced damage to the channel layer.
Solution Approach 2:
The dual-layer barrier structure acts as an intermediary between the etching process and the sensitive channel layer. The first barrier layer serves as a protective mediator that can be selectively removed to control etch depth, while the second barrier layer provides additional protection and structural support, thereby mediating the plasma exposure and reducing direct plasma-induced damage to the underlying channel region.
3Manufacturing precision
If selective etching is used to form gate recess, then etch depth precision improves, but process complexity increases
Solution Approach 1:
The patent exploits parameter changes in etch selectivity between different material layers. By designing the barrier layer with two distinct materials having different etch selectivity parameters, the process achieves precise depth control through natural self-limitation when the etch front reaches the second layer, reducing the need for complex real-time monitoring and control mechanisms.
Solution Approach 2:
The dual-layer barrier structure provides self-service etch depth control through its inherent material properties. The highly selective first layer automatically limits the etch depth by stopping the etching process when completely removed, exposing the second layer that has different etch characteristics. This self-limiting mechanism eliminates the need for complex external control systems, simplifying the overall process despite the additional material layer.
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
This approach enables the production of high-performance transistors with low defect density and precise etch control, addressing the limitations of conventional silicon-based transistors and improving the efficiency and reliability of power electronics.
Implementation Method 1
The first semiconductor material is selectively etchable over the second semiconductor material using a dry etching process
Data Source
AI summary
A semiconductor structure has a first layer that includes a first semiconductor material and a second layer that includes a second semiconductor material. The first semiconductor material is selectively etchable over the second semiconductor material using a first etching process. The first layer is disposed over the second layer. A recess is disposed at least in the first layer. Also described is a method of forming a semiconductor structure that includes a recess. The method includes etching a region in a first layer using a first etching process. The first layer includes a first semiconductor material. The first etching process stops at a second layer beneath the first layer. The second layer includes a second semiconductor material.