Semiconductor Device Trench Doping for Breakdown Voltage
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Solution Overview
Problem
Conventional semiconductor devices, such as IGBTs, face challenges in achieving optimal breakdown voltage and carrier accumulation effects due to limitations in trench section design and doping concentration distribution, which affect switching speed and turn-off loss.
Innovation Solution
The semiconductor device incorporates a unique trench section and doping region configuration, including first and second accumulation regions, an intermediate region, and a pillar region with specific doping concentration distributions and geometries to enhance carrier accumulation and reduce turn-off loss, while also optimizing the position and number of opening sections to manage carrier extraction and injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional trench section design is used, then the device structure is simple, but the breakdown voltage is insufficient
Solution Approach 1:
The drift region is divided into multiple sections with different doping concentrations (first drift region with lower concentration and second drift region with higher concentration). This segmentation allows the device to achieve high breakdown voltage in the lower-concentration region while maintaining good carrier accumulation in the higher-concentration region, resolving the contradiction between breakdown voltage and device performance without excessive complexity
Solution Approach 2:
Different regions of the drift region are assigned different doping concentrations to optimize local functions. The first drift region has lower doping concentration for high breakdown voltage, while the second drift region has higher doping concentration for carrier accumulation. This local quality differentiation resolves the contradiction by allowing each region to perform its optimal function
2Reliability
If the doping concentration in the drift region is increased, then the carrier accumulation effect is improved, but the breakdown voltage decreases
Solution Approach 1:
The drift region is segmented into first and second drift regions with different doping concentrations. The first drift region maintains lower concentration for high breakdown voltage, while the second drift region has higher concentration for carrier accumulation. This segmentation resolves the contradiction by separating the conflicting requirements into different spatial zones
Solution Approach 2:
Different doping concentrations are applied to different regions of the drift region to satisfy different functional requirements. The lower-concentration region provides high breakdown voltage characteristics, while the higher-concentration region provides strong carrier accumulation, resolving the contradiction through localized property optimization
3Productivity
If the trench section extends deep into the substrate, then the carrier extraction is improved, but the turn-off loss increases
Solution Approach 1:
The doping concentration is varied locally within the drift region to optimize carrier extraction while controlling turn-off loss. The higher doping concentration in the second drift region enhances carrier extraction efficiency, while the overall structure design maintains acceptable turn-off loss characteristics by balancing the doping profile
4Power
If the opening section is positioned to overlap the gap, then the carrier injection is enhanced, but the breakdown voltage is reduced
Solution Approach 1:
The opening section is positioned to overlap with the gap between trench sections to enhance carrier injection through the accumulation region. Simultaneously, the drift region doping concentration is optimized to maintain high breakdown voltage, resolving the contradiction by coordinating the positioning of the opening with the doping profile design
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 configuration improves breakdown voltage, reduces turn-off loss, and maintains injection enhancement effects, leading to enhanced switching performance and reduced ON voltage.
Implementation Method 1
a first accumulation region of a first conductivity type that is provided between the base region and the drift region and that has a higher doping concentration than the drift region. The semiconductor device may include a second accumulation region of a first conductivity type that is provided at a position deeper than the first accumulation region and that has a higher doping concentration than the drift region
Implementation Method 2
an intermediate region of a second conductivity type that is provided between the first accumulation region and the second accumulation region
Implementation Method 3
A first gap may be present between the first accumulation region and the first trench section. The second accumulation region may overlap the first gap in a depth direction of the semiconductor substrate
Data Source
AI summary
A semiconductor device includes a first trench section provided from an upper surface of a semiconductor substrate to inside the semiconductor substrate; a base region of a second conductivity type in direct contact with the first trench section between the upper surface of the semiconductor substrate and a drift region; a first accumulation region of a first conductivity type that is provided between the base region and the drift region and that has a higher doping concentration than the drift region; a second accumulation region of a first conductivity type that is provided at a position deeper than the first accumulation region and that has a higher doping concentration than the drift region; and an intermediate region of a second conductivity type that is provided between the first accumulation region and the second accumulation region, where the second accumulation region has a first opening section.