IGBT Anode Doping Layout for Low Voltage Drop and Fast Turn-Off
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional insulated gate bipolar transistors (IGBTs) face a trade-off between low on-state voltage drop and large safe operating area, where enhanced carrier implantation efficiency for lower voltage drop reduces the switching speed and increases turn-off loss.
Innovation Solution
The IGBT design includes specific regions with varying dopant concentrations and structures, such as a drift region, body region, cathode and anode regions, and a buffer layer, which enhance hole implantation efficiency in the on-state while reducing it during turn-off, allowing for a lower on-state voltage drop and larger safe operating area without the need for complex dual-gate control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If carrier implantation efficiency is enhanced to obtain lower on-state voltage drop, then on-state voltage drop is reduced, but safe operating area is reduced and turn-off loss increases
Solution Approach 1:
The anode second conductivity-type region is segmented into multiple regions (first through fourth regions) with different dopant concentrations arranged in alternating pattern. This segmentation allows different portions to serve different functions: some regions enhance carrier implantation for low on-state voltage drop, while others limit excessive carrier concentration to maintain safe operating area and reduce turn-off loss.
Solution Approach 2:
Different regions within the anode second conductivity-type region are assigned different dopant concentrations tailored to local requirements. Regions closer to the body region have higher dopant concentrations to enhance carrier implantation efficiency, while regions farther away have lower concentrations to prevent excessive carrier accumulation and reduce tail current effects during turn-off.
2Loss of energy
If carrier implantation efficiency is enhanced to obtain lower on-state voltage drop, then on-state voltage drop is reduced, but switching speed decreases and turn-off loss increases
Solution Approach 1:
The segmented anode region structure enables different portions to contribute differently during switching operations. The higher doped regions provide strong carrier implantation capability for fast turn-on, while the lower doped regions prevent excessive carrier storage that would slow down turn-off, thereby maintaining high switching speed with low turn-off loss.
Solution Approach 2:
By varying the dopant concentration parameter across different regions of the anode second conductivity-type region, the patent optimizes the balance between turn-on speed and turn-off speed. The alternating pattern of high and low dopant concentrations creates optimal conditions for rapid switching while minimizing tail current effects.
3Loss of energy
If increased carrier concentration is used to reduce on-state voltage drop, then on-state voltage drop is reduced, but safe operating area is reduced
Solution Approach 1:
The alternating pattern of high and low dopant concentration regions creates a balanced carrier distribution. The high doped regions provide sufficient carriers for low on-state voltage drop, while the low doped regions prevent excessive carrier concentration that would limit the safe operating area, especially under short-circuit conditions.
Solution Approach 2:
Different local regions have optimized dopant concentrations according to their specific functional requirements. Regions requiring high carrier density for low voltage drop are provided with higher dopant concentrations, while regions where excessive carriers would be harmful are provided with lower concentrations, achieving both low on-state voltage drop and large safe operating area simultaneously.
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 design achieves a lower on-state voltage drop and reduced turn-off loss, improving the switching speed and safe operating area by optimizing carrier implantation efficiency through the use of distinct dopant concentration regions and a buffer layer.
Implementation Method 1
the carrier implantation efficiency thereof needs to be enhanced
Implementation Method 2
enhance hole implantation efficiency in the on-state while reducing it during turn-off
Data Source
AI summary
An insulated gate bipolar transistor, comprising an anode second conductivity-type region and an anode first conductivity-type region provided on a drift region; the anode first conductivity-type region comprises a first region and a second region, and the anode second conductivity-type region comprises a third region and a fourth region, the dopant concentration of the first region being less than that of the second region, the dopant concentration of the third region being less than that of the fourth region, the third region being provided between the fourth region and a body region, the first region being provided below the fourth region, and the second region being provided below the third region and located between the first region and the body region.