Group III Nitride Passivation for Hydrogen Barrier Activation
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Solution Overview
Problem
Existing passivation schemes for Group III nitride semiconductor devices are inadequate in mitigating surface charge effects, leading to degradation and drift in device performance.
Innovation Solution
A method involving the formation of a first passivation layer as a hydrogen diffusion barrier on a Group III nitride substrate, followed by exposing specific regions of doped Group III nitride regions, activating these regions while the passivation layer is in place, and then forming a second passivation layer to further protect the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passivation layer is formed on Group III nitride semiconductor devices, then the device is protected from environmental conditions, but surface charge effects still occur that hinder proper modulation of the conductive channel
Solution Approach 1:
The passivation structure is divided into multiple segments: a first passivation layer (silicon nitride) deposited before doping to provide hydrogen barrier and reduce surface charge, and a second passivation layer (silicon oxide) deposited after doping to provide additional protection. This segmented approach allows each layer to perform its specific function optimally.
Solution Approach 2:
The first passivation layer is deposited on the substrate before the doped region is formed. This preliminary action ensures that the hydrogen barrier is in place before doping occurs, preventing hydrogen diffusion into the doped region and reducing surface charge effects that would otherwise hinder channel modulation.
2Reliability
If dopant activation is performed after forming a passivation layer, then hydrogen diffusion is prevented, but the dopant activation process becomes more complex
Solution Approach 1:
The first passivation layer is formed before dopant implantation and activation. This preliminary formation of the hydrogen barrier layer prevents hydrogen diffusion during the subsequent high-temperature activation process, eliminating the need for additional hydrogen passivation steps and actually simplifying the overall process while improving reliability.
Solution Approach 2:
The passivation layer composition and deposition parameters are optimized to provide sufficient hydrogen barrier properties at the required thickness, allowing the layer to serve multiple functions (hydrogen barrier, surface charge reduction) without requiring excessive thickness that would complicate subsequent processing.
3Object-generated harmful factors
If the first passivation layer is formed before doped region formation, then surface charge effects are reduced, but the manufacturing process requires additional process steps
Solution Approach 1:
The passivation function is segmented into two distinct layers with different deposition timings: the first layer (silicon nitride) deposited before doping to address surface charge, and the second layer (silicon oxide) deposited after doping to provide final protection. Each layer is optimized for its specific function.
Solution Approach 2:
The first passivation layer performs multiple functions simultaneously: it serves as a hydrogen diffusion barrier during doping and activation, and it reduces surface charge effects on the Group III nitride surface. This multi-functionality justifies the additional process step by eliminating the need for separate hydrogen passivation steps.
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 significantly reduces gate leakage currents by improving the side wall quality of the gate structure and prevents hydrogen diffusion during activation, thereby enhancing the reliability and performance of Group III nitride semiconductor devices.
Implementation Method 1
The first passivation layer may be configured as a hydrogen diffusion barrier
Data Source
Figure 1A~1B
Figure 2A~2E
Figure 2F~2I
AI summary
According to the invention, a method is provided which comprises providing a Group III nitride-based substrate comprising a first major surface and at least one doped Group III nitride region comprising dopants of a first conductivity type, forming a first passivation layer on the first major surface, wherein the first passivation layer is configured as a hydrogen diffusion barrier, forming at least one first opening in the first passivation layer and exposing at least a portion of the at least one doped Group III nitride region from the first passivation layer, activating the first doped Group III nitride region whilst the first passivation layer is located on the first major surface and the at least a portion of the at least one doped Group III nitride region is exposed from the first passivation layer, forming a second passivation layer on the first passivation layer and on the at least one doped Group III nitride region, forming at least one second opening in the first and second passivation layers and exposing a portion of the at least one doped Group III nitride region and forming a contact in the second opening.