Semiconductor Buffer Region Peak Doping for Electric Field Smoothing
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Solution Overview
Problem
Conventional semiconductor devices face challenges in relaxing electric field concentration on the buffer region, leading to issues such as electric field peaks and oscillations in gate voltage during switching operations.
Innovation Solution
A semiconductor device with a buffer region having multiple doping concentration peaks, including a shallowest peak closest to the substrate surface, a high concentration peak above it, and one or more low concentration peaks, which are arranged to distribute the electric field uniformly and prevent depletion layer spreading, thereby reducing electric field concentration and oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional buffer region with uniform doping concentration is used, then the device structure is simple, but electric field concentration occurs leading to oscillations in gate voltage
Solution Approach 1:
The buffer region is segmented into multiple doping concentration regions with different peak values arranged in the depth direction. This segmentation creates a stepped doping profile that distributes the electric field more uniformly, preventing concentration at a single point and thereby suppressing gate voltage oscillations during switching operations.
Solution Approach 2:
Different regions within the buffer region are assigned different doping concentrations locally. The doping concentration peaks are strategically positioned at specific depths, with each peak serving a local function in electric field management. This local variation in doping quality optimizes the electric field distribution without requiring complete restructuring of the entire device.
2Reliability
If the doping concentration in the buffer region is increased to prevent depletion layer spreading, then the field stop function is improved, but electric field concentration worsens
Solution Approach 1:
The buffer region is divided into multiple doping concentration peaks at different depths, each contributing to the field stop function. This segmentation allows the depletion layer to be distributed across multiple regions rather than concentrated at one interface, maintaining effective field stopping while reducing peak electric field stress through the stepped concentration profile.
Data Source
AI summary
Provided is a semiconductor device, including: a drift region of a first conductivity type which is provided in a semiconductor substrate, and a buffer region of the first conductivity type which is provided between the drift region and a lower surface of the semiconductor substrate, and has three or more concentration peaks higher than a doping concentration of the drift region of the semiconductor substrate in a depth direction. Three or more of the concentration peaks includes a shallowest peak closest to the lower surface of the semiconductor substrate, a high concentration peak arranged at an upper side than the lower surface of the semiconductor substrate than the shallowest peak, and one or more low concentration peaks arranged at an upper side than the lower surface of the semiconductor substrate than the high concentration peak and of which the doping concentration is ⅕ or less of the high concentration peak.