GaN Transistor Blocking Film Layout for Leakage Suppression
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Solution Overview
Problem
Existing semiconductor devices using Group 13 element nitrides face challenges in achieving high breakdown voltage and low on-resistance due to current leakage paths caused by crystal defects and pinholes formed during the deposition of terminals and gate electrodes, particularly when using amorphous glass substrates.
Innovation Solution
Incorporation of a plurality of blocking films made of insulating materials over an orientation-controlling film to prevent current leakage by covering the terminals and gate electrodes, promoting crystallization in the c-axis direction without the need for high-temperature epitaxial growth, and using a sputtering method to form the active layer and electron-supplying layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If terminals and gate electrodes are deposited over the active layer, then electrical connection is established, but current leakage paths are created due to crystal defects and pinholes
Solution Approach 1:
An insulating film is introduced as an intermediary layer between the active layer and the terminals/gate electrodes. This insulating film acts as a mediator that prevents direct contact and potential current leakage paths while still allowing electrical connection to be established through controlled interfaces, thereby resolving the contradiction between establishing electrical connection and preventing current leakage.
Solution Approach 2:
The device structure is segmented into distinct functional layers: the active layer containing Group 13 element nitride, an insulating film layer, and then the terminals/gate electrodes. This segmentation separates the electrical connection function from the current blocking function, allowing each layer to optimize its specific role and prevent current leakage through the terminals and gate electrodes.
2Stability of the object's composition
If high-temperature epitaxial growth is used to grow nitrides of Group 13 elements, then high crystallinity is achieved, but amorphous glass substrates cannot be used
Solution Approach 1:
The deposition parameters are changed from high-temperature epitaxial growth to low-temperature sputtering deposition. This parameter change allows the active layer to be formed on amorphous glass substrates without requiring high temperatures, thereby expanding substrate selection while maintaining the necessary crystalline structure through the sputtering process and subsequent crystallization.
Solution Approach 2:
The thermal field-based epitaxial growth process is replaced with a mechanical field-based sputtering deposition process. This substitution eliminates the need for high temperatures that would damage amorphous glass substrates, while still achieving the desired crystalline structure through controlled sputtering and low-temperature crystallization.
3Temperature
If sputtering method is used to form active layer and electron-supplying layer, then low-temperature deposition is achieved, but manufacturing complexity increases
Solution Approach 1:
The sputtering deposition method is used to form multiple layers (active layer and electron-supplying layer) in a single manufacturing process step. This multi-functional approach allows low-temperature deposition of different material layers without requiring separate deposition processes, thereby reducing overall manufacturing complexity despite the sophisticated nature of sputtering.
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 solution results in a highly reliable transistor with high breakdown voltage and low on-resistance, suitable for applications requiring high current and voltage, such as power devices and display devices, by effectively blocking current leakage paths and maintaining crystallinity.
Implementation Method 1
a plurality of blocking films located over the first orientation-controlling film and including an insulating material
Implementation Method 2
promoting crystallization in the c-axis direction without the need for high-temperature epitaxial growth
Implementation Method 3
using a sputtering method to form the active layer and electron-supplying layer
Data Source
AI summary
A transistor includes a first orientation-controlling film, a plurality of blocking films located over the first orientation-controlling film and including an insulating material, an active layer located over the plurality of blocking films and containing a gallium nitride-based compound, and a first terminal and a second terminal over the active layer. An entire bottom surface of the first terminal overlaps one of the plurality of blocking films and an entire bottom surface of the second terminal overlaps another one of the plurality of blocking films.