Silicon Gettering Layer for GaN HEMT Current Collapse
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Solution Overview
Problem
Current semiconductor devices using nitride semiconductors like GaN suffer from current collapse due to impurities such as oxygen on the surface, which capture electrons and reduce output.
Innovation Solution
A method involving the formation of a silicon layer on the nitride semiconductor device, followed by thermal treatment to getter oxygen, and the subsequent deposition of an insulating silicon nitride layer to suppress current collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a nitride semiconductor layer is used for high frequency output amplifier, then the device can operate at high frequency, but current collapse occurs due to oxygen impurities on the surface capturing electrons
Solution Approach 1:
A silicon layer is formed on the nitride semiconductor layer before final device completion. This preliminary silicon layer acts as a gettering layer that captures oxygen impurities on the surface, preventing them from capturing electrons and causing current collapse during high frequency operation.
Solution Approach 2:
The silicon layer serves as an intermediary between the nitride semiconductor layer and the external environment. It mediates the interaction by capturing oxygen impurities that would otherwise reach the nitride semiconductor surface and cause harmful electron capture, thus protecting the device while maintaining high frequency performance.
2Reliability
If thermal treatment is applied to remove oxygen impurities, then current collapse is suppressed, but the process complexity increases
Solution Approach 1:
The silicon layer performs self-service by automatically gettering oxygen impurities through thermal treatment. The silicon material inherently has a strong affinity for oxygen, and when subjected to thermal treatment, it spontaneously captures and holds oxygen impurities on its own, eliminating the need for additional complex impurity removal processes.
3Reliability
If a silicon layer is formed on the nitride semiconductor layer, then oxygen impurities are captured, but the manufacturing process becomes more complex
Solution Approach 1:
The formation of the silicon layer is merged with existing manufacturing processes. The silicon layer can be deposited using standard semiconductor fabrication techniques such as chemical vapor deposition or physical vapor deposition, which are already part of the nitride semiconductor manufacturing process flow, thereby minimizing additional process complexity.
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 method effectively reduces current collapse by capturing oxygen impurities, thereby enhancing the output and performance of semiconductor devices like HEMTs.
Implementation Method 1
thermally treating the nitride semiconductor layer in the process of forming the silicon layer or after the process of forming the silicon layer
Data Source
AI summary
A method for fabricating a semiconductor device including: forming a silicon layer on an upper face of a nitride semiconductor layer including a channel layer of a FET; thermally treating the nitride semiconductor layer in the process of forming the silicon layer or after the process of forming the silicon layer; and forming an insulating layer on an upper face of the silicon layer after the process of forming the silicon layer.