Halogen Ion Implantation in Gate Insulating Film for Normally Off HEMT
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Solution Overview
Problem
Nitride semiconductor-based high electron mobility transistors (HEMTs) face challenges in becoming normally off due to leakage currents, with existing methods like ion implantation damaging the semiconductor layers and degrading device characteristics.
Innovation Solution
A semiconductor device structure is developed where halogen ions, such as fluorine or chlorine, are implanted into the gate insulating film rather than the nitride semiconductor layers, creating regions within the insulating films to suppress leakage currents and ensure the device operates normally off without damaging the semiconductor layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If negative ions are implanted into nitride semiconductor layers to make the device normally off, then the device can be made normally off, but the semiconductor layers suffer significant damage and device characteristics are degraded
Solution Approach 1:
The patent introduces a gate insulating film as an intermediary layer between the gate electrode and the nitride semiconductor layer. Negative ions are implanted into this insulating film rather than directly into the semiconductor layer, allowing the insulating film to mediate the harmful effects of ion implantation while still achieving the desired normally off capability through suppression of leakage current.
Solution Approach 2:
The patent converts the potentially harmful effect of negative ion implantation into a beneficial effect by directing the ion implantation into the gate insulating film rather than the semiconductor layer. The negative ions, which would normally damage the semiconductor layer, are instead used to modify the insulating film to suppress leakage current, thereby achieving normally off capability without damaging the semiconductor structures.
2Reliability
If a p-GaN cap layer is formed on the electron supply layer to make the device normally off, then the device can be made normally off, but the crystal growth process becomes difficult
Solution Approach 1:
The patent changes the approach from modifying semiconductor layer composition (p-GaN cap layer requiring complex crystal growth parameters) to modifying the gate insulating film through negative ion implantation. This parameter change shifts the control mechanism from semiconductor material science to insulating film modification, simplifying the manufacturing process while achieving the same normally off effect.
3Reliability
If a gate recess is formed on the electron supply layer to make the device normally off, then the device can be made normally off, but the formation may be insufficient to ensure normally off operation
Solution Approach 1:
The patent uses the gate insulating film as an intermediary to achieve normally off capability, avoiding the need for precise gate recess formation in the semiconductor layer. The insulating film serves as the medium for negative ion implantation, eliminating the manufacturing precision challenges associated with forming accurate gate recesses in the nitride semiconductor 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 allows for a stable HEMT operation that is normally off with a small fluctuation range of the gate threshold voltage, maintaining device characteristics and preventing semiconductor layer damage.
Implementation Method 1
in the first insulating film, a region containing halogen ions is formed under a region provided with the electrode
Data Source
AI summary
A semiconductor device includes: a first semiconductor layer formed over a substrate; a second semiconductor layer formed over the first semiconductor layer; an insulating film including a first insulating film formed over the second semiconductor layer, a second insulating film, and a third insulating film stacked sequentially over the first insulating film, and an electrode formed over the insulating film, wherein, in the first insulating film, a region containing halogen ions is formed under a region provided with the electrode, and the third insulating film contains a halogen.