GaN Guard Ring Formation by Ion Implantation Without Etching
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Solution Overview
Problem
The formation of p-type regions in gallium nitride (GaN) semiconductor devices using ion implantation is challenging due to the need for high-temperature activation annealing, which can lead to decomposition, and existing methods struggle to control etching depth and prevent junction damage during guard ring formation.
Innovation Solution
A method involving selective ion-implantation of nitrogen atoms and p-type impurities into a gallium nitride layer, followed by thermal treatment to diffuse the p-type impurities, creating a p-type region with controlled depth and concentration, thereby forming a guard ring structure without etching and minimizing junction damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ion implantation is used to form p-type regions in GaN, then field relaxation can be achieved, but high-temperature activation annealing is required which causes decomposition
Solution Approach 1:
The patent changes the temperature parameter by introducing a low-temperature annealing process (700-900°C) instead of the conventional high-temperature annealing, making the process compatible with GaN's thermal stability limits while still achieving p-type region formation
Solution Approach 2:
The patent replaces the conventional high-temperature thermal activation process with a low-temperature annealing process combined with a specific atmosphere control, substituting the mechanical/thermal system with a chemically-controlled system that prevents decomposition
2Ease of manufacture
If etching is used to remove p-GaN for guard ring formation, then guard rings can be formed, but etching depth control is difficult and junction damage occurs
Solution Approach 1:
The patent extracts the etching step from the guard ring formation process entirely, replacing it with selective ion implantation that directly creates the p-type regions without requiring material removal, thereby eliminating depth control issues and junction damage
Solution Approach 2:
The patent performs preliminary ion implantation of p-type impurities at specific depths before final annealing, pre-establishing the p-type region boundaries without etching, which prevents junction damage and ensures precise depth 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 approach allows for the easy formation of p-type regions in GaN semiconductor devices, enhancing field relaxation and withstand voltage by creating a stable p-type region with precise control over impurity distribution, avoiding the limitations of etching-based methods.
Implementation Method 1
selectively ion-implanting an element that is other than p-type impurities and n-type impurities into a first region in a first primary surface of a gallium nitride layer so as to generate crystal defects in the first region
Implementation Method 2
selectively ion-implanting a p-type impurity into a second region in the gallium nitride layer
Implementation Method 3
thermally treating said gallium nitride layer that has been ion-implanted with said element and said p-type impurity so as to thermally diffuse said p-type impurity in the second region into a third region that is within the first region and that surrounds a bottom and sides of the second region
Data Source
AI summary
A method for manufacturing a nitride semiconductor device includes: selectively ion-implanting an element that is other than p-type impurities and n-type impurities into a first region in a first primary surface of a gallium nitride layer so as to generate crystal defects in the first region; selectively ion-implanting a p-type impurity into a second region in the gallium nitride layer, the second region being shallower than the first region in a depth direction and being within the first region in a plan view; and thermally treating said gallium nitride layer that has been ion-implanted with said element and said p-type impurity so as to thermally diffuse said p-type impurity in the second region into a third region that is within the first region and that surrounds a bottom and sides of the second region.