Nitride Semiconductor Groove P-Type Impurity Confinement
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Solution Overview
Problem
Existing methods for forming a p-type impurity region in Group III nitride semiconductor devices result in unintended impurity regions due to lateral diffusion during ion implantation, leading to device performance issues.
Innovation Solution
A method involving the formation of a groove in the p-type layer before heat treatment to confine the ion-implanted region, ensuring the p-type impurity region is formed only in the intended area by diffusing p-type impurities through the heat treatment process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ion implantation is performed to form a p-type impurity region, then p-type doping is achieved, but lateral diffusion causes impurities to spread to unintended regions
Solution Approach 1:
The p-type layer is divided into multiple regions by grooves, isolating the ion-implanted region from adjacent areas. This segmentation prevents lateral diffusion of impurities to unintended regions while maintaining effective doping in the target area.
Solution Approach 2:
Grooves are formed in the p-type layer before ion implantation to establish physical boundaries. This preliminary action creates containment structures that will restrict subsequent impurity diffusion during the doping process.
2Manufacturing precision
If heat treatment is applied to diffuse p-type impurity into the n-type layer, then p-type impurity region is formed, but impurities diffuse horizontally as well as vertically
Solution Approach 1:
The p-type layer is segmented by grooves into isolated regions. During heat treatment, p-type impurities diffuse vertically into the n-type layer within each segmented region but are contained horizontally by the groove boundaries, achieving precise spatial control.
Solution Approach 2:
The groove structure creates different diffusion characteristics in different directions: vertical diffusion is permitted and controlled into the n-type layer, while horizontal diffusion is blocked by the groove walls. This anisotropic diffusion control achieves the desired impurity distribution.
3Ease of manufacture
If a p-type layer is formed on the n-type layer before ion implantation, then the intended structure is created, but the p-type layer allows lateral spread of implanted ions
Solution Approach 1:
The continuous p-type layer is segmented into isolated regions by grooves. This segmentation maintains the ease of forming a p-type layer while adding the functionality of confining ion implantation to specific areas, preventing lateral spread.
Solution Approach 2:
The grooves act as intermediary structures between the ion source and the n-type layer. They allow vertical ion transmission for doping while blocking lateral ion migration, serving as a selective barrier that reconciles the conflicting requirements.
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 effectively restricts the diffusion of p-type impurities to the intended region, enhancing device structure design and performance by preventing lateral spread, thus improving breakdown voltage and reliability.
Implementation Method 1
forming a groove having a depth reaching the first n-type layer in a predetermined region of the surface of the first p-type layer and dividing the first p-type layer so that the ion implanted region is included in the divided first p-type layer
Implementation Method 2
forming a p-type impurity region in a region with a predetermined depth from the surface of the first n-type layer and a width of the first p-type layer below the ion implanted region by diffusing p-type impurity in the first p-type layer through heat treatment
Implementation Method 3
forming an ion implanted region by ion implantation into the surface of the first p-type layer after the first step
Data Source
AI summary
An ion implanted region is formed by implanting Mg ions into a predetermined region of the surface of the first p-type layer. Subsequently, a second n-type layer is formed on the first p-type layer and the ion implanted region. A trench is formed by dry etching a predetermined region of the surface of the second n-type layer until reaching the first n-type layer. Next, heat treatment is performed to diffuse Mg. Thus, a p-type impurity region is formed in a region with a predetermined depth from the surface of the first n-type layer below the ion implanted region. Since the trench is formed before the heat treatment, Mg is not diffused laterally beyond the trench. Therefore, the width of the p-type impurity region is almost the same as the width of the first p-type layer divided by the trench.