IGBT Buffer Region Doping Profile for Latch-Up Suppression
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Solution Overview
Problem
Existing semiconductor devices face challenges in effectively managing the expansion of the depletion layer and suppressing latch-up events, particularly at room temperature, due to limitations in the doping concentration distribution in the buffer region.
Innovation Solution
The semiconductor device incorporates a buffer region with a specific doping concentration distribution, featuring multiple concentration peaks and valleys, which are strategically positioned to prevent the depletion layer from reaching the collector region and to reduce the slope of the collector-emitter voltage during turn-off, thereby enhancing latch-up withstand capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a field stopper layer is provided in the IGBT device, then the depletion layer expansion is suppressed, but the latch-up withstand capability is insufficient at room temperature
Solution Approach 1:
The patent applies local quality by creating specific doping concentration peaks at defined depth positions within the buffer region. The first concentration peak is positioned at 0.05μm to 0.20μm from the lower surface, and the second concentration peak at 0.30μm to 0.50μm, with each peak having specific concentration ranges (1×10^16 to 1×10^18 atoms/cm³ for the first peak, 1×10^15 to 1×10^17 atoms/cm³ for the second peak). This localized doping strategy creates electric field distribution that simultaneously suppresses depletion layer expansion and enhances latch-up withstand capability at room temperature.
Solution Approach 2:
The patent implements parameter changes by precisely controlling the doping concentration distribution through multiple peaks at different depths and concentrations. The first concentration peak (1×10^16 to 1×10^18 atoms/cm³) and second concentration peak (1×10^15 to 1×10^17 atoms/cm³) are positioned at specific depths to modify the electric field characteristics. This parameter optimization enables the device to achieve both depletion layer suppression and improved latch-up performance without the harmful effects of uniform high doping throughout the buffer region.
2Object-affected harmful factors
If the doping concentration in the buffer region is increased to suppress depletion layer expansion, then the depletion layer is contained, but switching losses increase
Solution Approach 1:
The patent applies local quality by concentrating doping atoms at specific depth positions rather than uniformly distributing them throughout the buffer region. The first concentration peak at 0.05μm to 0.20μm and the second concentration peak at 0.30μm to 0.50μm create localized electric field control zones. This approach suppresses depletion layer expansion only where needed while maintaining lower doping concentrations in other regions, thereby reducing carrier scattering and minimizing switching losses.
Solution Approach 2:
The patent implements partial action by applying doping only at specific critical depths rather than throughout the entire buffer region. The first concentration peak (1×10^16 to 1×10^18 atoms/cm³) and second concentration peak (1×10^15 to 1×10^17 atoms/cm³) provide sufficient electric field control to contain the depletion layer while avoiding excessive doping that would increase switching losses. This selective doping strategy achieves the minimum necessary action for depletion layer suppression without the harmful effects of over-doping.
3Reliability
If the slope of collector-emitter voltage during turn-off is reduced to prevent latch-up, then latch-up withstand capability is improved, but the depletion layer control is insufficient
Solution Approach 1:
The patent applies local quality by creating two distinct doping concentration peaks at different depths to simultaneously address multiple functions. The first concentration peak (1×10^16 to 1×10^18 atoms/cm³ at 0.05μm to 0.20μm) controls the electric field near the collector region to prevent depletion layer penetration, while the second concentration peak (1×10^15 to 1×10^17 atoms/cm³ at 0.30μm to 0.50μm) modulates the voltage slope during turn-off. This localized functional differentiation resolves the contradiction between depletion layer control and latch-up suppression.
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 effectively suppresses the expansion of the depletion layer and reduces the likelihood of latch-up events, particularly at room temperature, while maintaining efficient carrier injection and reducing switching losses, thus improving the overall performance of the semiconductor device.
Implementation Method 1
a buffer region 20 with a specific doping concentration distribution, featuring multiple concentration peaks and valleys, which are strategically positioned to prevent the depletion layer from reaching the collector region
Implementation Method 2
strategically positioned to prevent the depletion layer from reaching the collector region and to reduce the slope of the collector-emitter voltage during turn-off, thereby enhancing latch-up withstand capability
Implementation Method 3
while maintaining efficient carrier injection and reducing switching losses, thus improving the overall performance of the semiconductor device
Data Source
AI summary
Provided is a semiconductor device comprising: a semiconductor substrate provided with a drift region; a buffer region arranged between the drift region and the lower surface, wherein a doping concentration distribution has three or more concentration peaks; and a collector region arranged between the buffer region and the lower surface, wherein the three or more concentration peaks in the buffer region include: a first concentration peak closest to the lower surface; a second concentration peak closest, next to the first concentration peak, to the lower surface, arranged 5 μm or more distant from the lower surface in the depth direction, and having a doping concentration lower than the first concentration peak, the doping concentration being less than 1.0×1015/cm3; and a high concentration peak arranged farther from the lower surface than the second concentration peak, and having a higher doping concentration than the second concentration peak.