Nitride Semiconductor Layer With Graded Silicon Concentration
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Solution Overview
Problem
Current nitride semiconductor wafers face challenges in achieving high-quality crystal with few dislocations, which is essential for optimal performance in optical and electronic devices.
Innovation Solution
A nitride semiconductor layer with a stacked multilayer structure is formed on a substrate, comprising a lower layer, an intermediate layer, and an upper layer, each with specific silicon concentrations and thicknesses, grown using varying V/III ratios and temperatures to reduce dislocation density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single-layer nitride semiconductor structure is used, then the manufacturing process is simple, but the dislocation density is high which degrades device performance
Solution Approach 1:
The nitride semiconductor layer is divided into multiple stacked sub-layers (first nitride semiconductor layer, second nitride semiconductor layer, third nitride semiconductor layer) with different Si concentrations. This segmentation allows each layer to be optimized independently for dislocation management, transforming a single complex problem into manageable sequential layers that collectively reduce overall dislocation density while maintaining manufacturing feasibility.
Solution Approach 2:
Each nitride semiconductor layer is assigned a specific local quality characteristic - different Si concentrations (first concentration in first layer, second concentration in second layer, third concentration in third layer) - to address dislocation issues at specific depth positions. This local quality approach allows targeted control of dislocation generation and propagation in different regions of the semiconductor structure.
2Productivity
If high Si concentration is used to improve crystal quality, then growth speed increases, but dislocation density increases which harms crystal quality
Solution Approach 1:
The Si concentration is segmented across different layers rather than uniformly applied. The first nitride semiconductor layer uses a first Si concentration optimized for initial growth, the second layer uses a second Si concentration for intermediate growth, and the third layer uses a third Si concentration for final growth. This segmentation enables each layer to achieve optimal growth speed while controlling dislocation density locally.
Solution Approach 2:
The Si concentration parameter is changed systematically across the stacked layers. By varying the Si concentration (first concentration, second concentration, third concentration) in each successive layer, the growth conditions are dynamically adjusted to balance growth speed and dislocation density control at different stages of layer formation.
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 results in a nitride semiconductor wafer with significantly reduced dislocation density, enhancing the performance and efficiency of semiconductor devices such as light emitting and high-frequency electronic devices.
Implementation Method 1
a nitride semiconductor layer with a stacked multilayer structure is formed on a substrate, comprising a lower layer, an intermediate layer, and an upper layer, each with specific silicon concentrations and thicknesses, grown using varying V/III ratios and temperatures
Data Source
AI summary
According to one embodiment, a semiconductor device includes a functional layer of a nitride semiconductor. The functional layer is provided on a nitride semiconductor layer including a first stacked multilayer structure provided on a substrate. The first stacked multilayer structure includes a first lower layer, a first intermediate layer, and a first upper layer. The first lower layer contains Si with a first concentration and has a first thickness. The first intermediate layer is provided on the first lower layer to be in contact with the first lower layer, contains Si with a second concentration lower than the first concentration, and has a second thickness thicker than the first thickness. The first upper layer is provided on the first intermediate layer to be in contact with the first intermediate layer, contains Si with a third concentration lower than the second concentration, and has a third thickness.