Proton Buffer Layer Profile for IGBT Turn-Off Oscillation Suppression
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Solution Overview
Problem
Existing semiconductor devices, such as IGBTs, face challenges in fully suppressing oscillations during turn-off operations due to the impurity concentration profile of proton layers, which do not effectively relax electric field concentration and breakdown voltage.
Innovation Solution
A semiconductor device structure featuring a first buffer layer with a specific impurity concentration profile, including a maximum value in the second region, a kink at the boundary point between the first and second regions, and a third region with a distribution longer than 5 μm, where the impurity concentration is lower than the boundary point, effectively suppressing oscillations by relaxing the decrease in impurity concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional impurity concentration profile is used in the field stop layer, then the manufacturing process is simple, but oscillations during turn-off operations cannot be fully suppressed
Solution Approach 1:
The field stop layer is segmented into multiple regions (first region, second region, third region) with different impurity concentration characteristics. This segmentation allows each region to perform specific functions: the first region provides high impurity concentration for carrier retention, the second region provides a kink in the profile for electric field control, and the third region provides a gradual transition to suppress oscillations.
Solution Approach 2:
Different regions within the field stop layer are assigned different local impurity concentration qualities. The first region has high impurity concentration for carrier retention, the second region has a specific kink structure for electric field management, and the third region has lower concentration for oscillation suppression. This local differentiation resolves the contradiction by allowing each zone to optimize for its specific function.
2Productivity
If the impurity concentration of the proton layer peaks inside the phosphorus/arsenic layer, then productivity can be improved and product cost reduced, but oscillations are not fully suppressed
Solution Approach 1:
The field stop layer is divided into distinct regions with the proton layer peak positioned in the first region rather than inside the phosphorus/arsenic layer. This segmentation creates a three-region structure where the first region (with proton peak) provides carrier retention, the second region provides electric field control through a kink, and the third region provides oscillation suppression through gradual concentration decrease.
Solution Approach 2:
The impurity concentration profile parameters are changed by positioning the proton layer peak in the first region and creating specific kink characteristics in the second region. The profile is designed to have a maximum value in the first region, a kink at the boundary between first and second regions, and a gradual decrease in the third region, optimizing both productivity and oscillation suppression.
3Strength
If the impurity concentration decreases gradually from the phosphorus/arsenic layer toward the drift layer, then electric field concentration is relaxed and breakdown voltage is ensured, but oscillations during turn-off are not fully suppressed
Solution Approach 1:
The field stop layer is segmented into three regions with different concentration profiles. The first region maintains high impurity concentration for carrier retention, the second region introduces a kink for electric field control, and the third region provides a gradual decrease for oscillation suppression. This segmentation allows simultaneous achievement of breakdown voltage and oscillation suppression.
Solution Approach 2:
Different local concentration qualities are assigned to different regions: the first region has high concentration for carrier retention, the second region has a kink structure for electric field management, and the third region has a gradual decrease for oscillation suppression. This local differentiation resolves the contradiction between breakdown voltage and oscillation 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
The proposed structure effectively suppresses oscillations at turn-off by maintaining a stable impurity concentration profile, ensuring a wider carrier region and improved breakdown voltage, thus enhancing the semiconductor device's performance.
Implementation Method 1
It is widely known that proton implantation into silicon and a subsequent heat treatment generate donors contributing to n-type conductivity.
Implementation Method 2
proton implantation into silicon and a subsequent heat treatment generate donors contributing to n-type conductivity
Data Source
AI summary
A first buffer layer includes: a first region containing protons and in contact with a drift layer; a second region between the first region and a first principal surface containing protons, and in contact with the first region; and a third region between the second region of the first buffer layer and the first principal surface. An impurity concentration profile of the first buffer layer includes: a maximum value in the second region; a kink at a boundary point between the first region and the second region, relaxing or stopping a decrease from the maximum value; a value at the boundary point higher than or equal to 80% of the maximum value; and a distribution of the third region longer than or equal to 5 μm and having an impurity concentration lower than the value at the boundary point and lower than or equal to 5.0×1014/cm3.