Tilted Trench Gate Structures for Power Semiconductor Devices
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Power semiconductor devices with tilted main crystal directions face challenges in forming effective trench gate structures that compensate for angular misalignment, leading to reduced charge carrier mobility and device reliability.
Innovation Solution
The semiconductor device features trench gate structures with longitudinal axes tilted between 2 to 30 degrees to a horizontal plane, with mesa portions and sidewall sections that compensate for angular misalignment through thermal treatment and redeposition regions, forming high-mobility inversion channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If trench gate structures are formed with vertical sidewalls in off-axis semiconductor substrates, then manufacturing is simplified, but charge carrier mobility decreases due to angular misalignment between trench axes and main crystal planes
Solution Approach 1:
The patent introduces a tilt angle dimension to the trench gate structures, transitioning from purely vertical sidewalls to tilted sidewalls that align with main crystal planes. This dimensional change in the trench orientation compensates for the off-axis angle of the semiconductor substrate, enabling high charge carrier mobility while maintaining manufacturability through controlled thermal treatment processes
2Reliability
If trench gate structures are tilted to align with main crystal planes, then charge carrier mobility improves, but manufacturing complexity increases due to required thermal treatment and redeposition region formation
Solution Approach 1:
The patent utilizes parameter changes in the thermal treatment process, specifically controlling temperature and atmosphere conditions to induce controlled atomic rearrangement along main crystal planes. This transforms the substrate surface to form redeposition regions that enable trench gate structures with sidewalls aligned to high-mobility crystal planes, achieving improved charge carrier mobility through controlled physical-chemical parameter modifications
3Manufacturing precision
If thermal treatment is applied to form redeposition regions, then sidewall alignment to crystal planes improves, but thermal load on the device increases
Solution Approach 1:
The patent applies partial thermal treatment selectively to specific regions where trench gate structures are formed, rather than uniformly treating the entire semiconductor substrate. This localized approach achieves the necessary sidewall alignment and redeposition region formation only where needed, minimizing overall thermal load on the device while maintaining manufacturing precision for critical structures
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 enhances device reliability and charge carrier mobility by forming effective inversion channels along main crystal planes, reducing thermal load and leakage current, and improving device characteristics.
Implementation Method 1
the semiconductor substrate is heated up to a temperature at which atoms of the semiconductor material rearrange along main crystal planes
Implementation Method 2
atoms of the semiconductor material rearrange along main crystal planes, wherein redeposition regions form sidewalls steps
Data Source
AI summary
A semiconductor device includes a semiconductor body with a first main crystal direction parallel to a horizontal plane. Longitudinal axes of trench gate structures are tilted to the first main crystal direction by a tilt angle of at least 2 degree and at most 30 degree in the horizontal plane. Mesa portions are between neighboring trench gate structures. First sidewall sections of first mesa sidewalls are main crystal planes parallel to the first main crystal direction. Second sidewall sections tilted to the first sidewall sections connect the first sidewall sections.