SiC-GaN Transistor with Polysilicon Interconnection Layer
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Solution Overview
Problem
Conventional semiconductor materials like silicon and gallium arsenide are not well-suited for high power and high frequency applications due to their small bandgaps and breakdown voltages, necessitating the use of wide bandgap materials such as silicon carbide and Group III nitrides for improved performance in devices like High Electron Mobility Transistors (HEMTs).
Innovation Solution
A transistor structure incorporating a silicon carbide drift layer and a gallium nitride channel layer with a polysilicon interconnection layer, featuring a semiconductor blocking region and a control electrode to modulate the conductivity of a two-dimensional electron gas, enhancing voltage blocking capabilities and channel mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional semiconductor materials like silicon and gallium arsenide are used, then manufacturing ease and compatibility are maintained, but voltage blocking capacity and breakdown strength are insufficient for high power applications
Solution Approach 1:
The patent employs a composite semiconductor structure combining silicon carbide drift layer with gallium nitride channel layer. The silicon carbide provides high breakdown voltage and thermal stability, while the gallium nitride layer enables high electron mobility and low on-resistance. This composite approach allows the device to achieve both high voltage blocking capacity and good manufacturing compatibility by leveraging the complementary strengths of different semiconductor materials.
2Reliability
If wide bandgap materials like silicon carbide and Group III nitrides are used, then breakdown voltage and electron mobility are improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent divides the semiconductor device into functionally distinct segments: a silicon carbide drift layer for voltage blocking, a gallium nitride channel layer for high mobility transport, and a separately formed polysilicon interconnection layer. This segmentation allows each layer to be optimized for its specific function while simplifying the overall manufacturing process, as each material can be deposited and processed independently according to its specific requirements.
Solution Approach 2:
The patent introduces a polysilicon interconnection layer as an intermediary between the silicon carbide drift layer and the gallium nitride channel layer. This intermediate layer facilitates proper electrical connection and stress management between the two wide bandgap semiconductor layers, enabling them to work together effectively while reducing the direct complexity of interfacing dissimilar semiconductor materials.
3Reliability
If a semiconductor interconnection layer of different material is introduced between drift and channel layers, then electrical coupling and conductivity control are improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent utilizes parameter changes in the polysilicon interconnection layer, specifically controlling its crystalline structure and doping concentration, to optimize electrical coupling between the drift and channel layers. By adjusting these material parameters, the polysilicon layer can provide reliable electrical connection while accommodating reasonable manufacturing tolerances for layer alignment and thickness control.
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 configuration provides high voltage blocking capacity, reduced on-resistance, and improved switching speed, making it suitable for high power and high frequency applications while maintaining compatibility with subsequent thermal processes.
Implementation Method 1
a two-dimensional electron gas (2DEG) is formed at the heterojunction of two semiconductor materials with different bandgap energies, and where the smaller bandgap material has a higher electron affinity
Implementation Method 2
A major portion of the electrons in the 2DEG is attributed to polarization in the AlGaN
Implementation Method 3
the control electrode may be configured to modulate a conductivity of the two dimensional electron gas responsive to an electrical signal applied to the control electrode
Data Source
AI summary
A transistor may include a semiconductor drift layer of a first semiconductor material and a semiconductor channel layer on the semiconductor drift layer. The semiconductor channel layer may include a second semiconductor material different than the first semiconductor material. A semiconductor interconnection layer may be electrically coupled between the semiconductor drift layer and the semiconductor channel layer, and the semiconductor interconnection layer may include a third semiconductor material different than the first and second semiconductor materials. In addition, a control electrode may be provided on the semiconductor channel layer.