Semiconductor Device Buried Doped Region Edge Termination
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Solution Overview
Problem
Current transistor devices for power applications face challenges in achieving higher doping levels in the mesas of the active cell area to reduce RDSON and prevent avalanche generation at the surface edge of the termination structure.
Innovation Solution
The semiconductor device incorporates a buried doped region with specific positioning and depth within the edge termination region, forming part of the sidewalls of columnar termination trenches and extending laterally to surround the active area, which includes a grid-like pattern of gate trenches and a buried doped region to enhance doping and reduce surface breakdown risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If higher doping levels are implemented in the mesas of the active cell area, then the on-resistance (RDSON) is reduced, but the risk of avalanche generation moving to the surface at the outer edge of the termination structure increases
Solution Approach 1:
The patent applies local quality by implementing a buried doped region with specific doping concentration and depth parameters (Xdoped between 0.5-2.0 μm, Ndoped between 1e16-1e18 cm^-3) in the edge termination region. This localized doping modification creates different electrical properties in the termination region compared to the active cell area, allowing high doping in mesas for low RDSON while preventing avalanche generation at the surface edge through the specially designed buried doped region.
2Reliability
If the buried doped region is positioned closer to the surface, then the blocking capability is improved, but the risk of surface breakdown increases
Solution Approach 1:
The patent employs parameter changes by optimizing the depth position (Xdoped) and doping concentration (Ndoped) of the buried doped region. The depth is set between 0.5-2.0 μm from the surface, and the doping concentration between 1e16-1e18 cm^-3. These specific parameter ranges create an optimal balance where the buried doped region provides sufficient blocking capability to handle high voltages while maintaining safe distance from the surface to prevent avalanche generation and surface breakdown.
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 allows for higher doping levels, reducing the on-resistance and preventing early breakdown at the surface edge, thereby enhancing the reliability and robustness of the transistor device.
Implementation Method 1
a buried doped region (31) within the semiconductor body (12) spaced apart from the first surface (13) and from the second surface (32)
Data Source
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AI summary
A semiconductor device is provided that comprises a semiconductor body having a first surface, a second surface opposing the first surface and side faces, an active area, wherein the active area comprises a plurality of active transistor cells and an edge termination region laterally surrounding the active area. Each active transistor cell comprises a columnar trench comprising a field plate and a mesa comprising a drift region of a first conductivity type. The edge termination region comprises a plurality of inactive cells, each inactive cell comprising a columnar termination trench comprising a field plate and a termination mesa comprising a drift region of a first conductivity type. The edge termination region comprises a transition region laterally surrounding the active region and an outer termination region laterally surrounding the transition region. In the transition region, the termination mesa comprises a body region of the second conductivity type that is arranged on the drift region. In the outer termination region, the drift region of the termination mesa extends to the first surface. The edge termination region further comprises a buried doped region that has a lateral extent such that it is positioned in the transition region and in the outer termination region.