Nitride Semiconductor Recess Design for High Carrier Mobility
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Solution Overview
Problem
Current semiconductor devices using nitride semiconductors face challenges in achieving high mobility due to shallow recesses, which lead to low crystal quality and impurity introduction, resulting in inadequate carrier mobility.
Innovation Solution
A semiconductor device design with a deep recess depth and high ratio of recess depth to nitride region thickness, combined with a specific nitride region structure and insulating film composition, including AlxGa1-xN layers and SiO2/SiN films, to enhance crystallinity and reduce sodium impurity concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a shallow recess is formed in the nitride semiconductor layer, then the manufacturing process is simpler, but the crystal quality deteriorates and carrier mobility decreases
Solution Approach 1:
The patent changes the key parameter of recess depth from shallow to deep (ratio of recess depth to nitride region thickness of 0.5 or more), which fundamentally alters the crystal quality and carrier mobility characteristics. This parameter change resolves the contradiction by demonstrating that deeper recesses, while more complex to manufacture, produce superior crystal quality and higher carrier mobility that outweighs the manufacturing complexity.
Solution Approach 2:
The patent introduces a dimensional relationship (ratio of recess depth to nitride region thickness) as a new design dimension. By optimizing this ratio to be 0.5 or more, the patent transforms the simple depth control into a proportional design approach, allowing the recess depth to scale with the nitride region thickness while maintaining optimal crystal quality and carrier mobility.
2Manufacturing precision
If a deep recess is formed to improve crystal quality, then carrier mobility increases, but the manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by optimizing the recess depth to achieve a specific ratio (0.5 or more relative to nitride region thickness). This quantitative parameter optimization balances the manufacturing complexity against the achieved crystal quality improvement, showing that a deep recess with this specific ratio provides the optimal compromise between manufacturability and performance.
Solution Approach 2:
The patent employs partial action by forming a recess that extends into but does not completely penetrate the nitride semiconductor layer. The recess depth is controlled to be a specific proportion (ratio of 0.5 or more) of the nitride region thickness, achieving sufficient crystal quality improvement and carrier mobility enhancement without the excessive complexity of complete penetration or overly deep recesses.
3Manufacturing precision
If sodium impurity concentration is reduced to improve device performance, then carrier mobility increases, but additional process steps are required
Solution Approach 1:
The patent applies preliminary action by forming the deep recess structure before final device fabrication, which creates a configuration that inherently reduces sodium impurity concentration. The deep recess geometry, with its specific depth-to-thickness ratio, establishes a structure that limits impurity incorporation during subsequent processing steps, achieving impurity reduction as a built-in feature rather than requiring separate purification processes.
Data Source
AI summary
According to one embodiment, a semiconductor device includes a first electrode, a second electrode, a third electrode, a first nitride region, a second nitride region, and a first insulating film. The first nitride region includes Alx1Ga1-x1N. The first nitride region includes first and second partial regions, a third partial region between the first and second partial regions, a fourth partial region between the first and third partial regions, and a fifth partial region between the third and second partial regions. The second nitride region includes Alx2Ga1-x2N. The second nitride region includes sixth and seventh partial regions. The first insulating film includes a first insulating region and is between the third partial region and the third electrode. The third partial region has a first surface opposing the first insulating region. The fourth partial region has a second surface opposing the sixth partial region.