Semiconductor Circuit Reduces On-Resistance via Series Transistors
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Solution Overview
Problem
Existing semiconductor devices face challenges in achieving a balance between low on-resistance and high voltage blocking capability, with conventional power transistors requiring trade-offs between these parameters, and there is a need for a cost-efficient method to generate a supply voltage for control circuits.
Innovation Solution
A circuit arrangement featuring a first transistor with a drift region and multiple second transistors connected in series, where the source and gate electrodes of the second transistors are coupled to the drift region, allowing them to be controlled by the voltage drop across the drift region, thereby reducing on-resistance without compromising voltage blocking capability, and incorporating a simple and cost-effective means to generate the supply voltage for the control circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the length of the drift region is reduced or the doping concentration in the drift region is increased, then the on-resistance decreases, but the voltage blocking capability is reduced
Solution Approach 1:
The invention divides the drift region into multiple sections with different doping concentrations. The drift region comprises a first drift region section with a first doping concentration and a second drift region section with a second doping concentration, where the doping concentrations differ by at least one order of magnitude. This segmentation allows each section to be optimized for specific functions: the first section (with higher doping) reduces on-resistance while the second section (with lower doping) maintains voltage blocking capability.
Solution Approach 2:
The invention applies different doping concentrations to different parts of the drift region to achieve local optimization. The first drift region section has a higher doping concentration to reduce resistance in areas where current flows heavily, while the second drift region section has a lower doping concentration to maintain high voltage blocking capability in areas where voltage stress is concentrated. This local quality differentiation resolves the contradiction between low on-resistance and high voltage blocking capability.
2Loss of energy
If compensation regions or field plates are provided in the drift region, then the doping concentration can be increased to reduce on-resistance, but the device complexity increases
Solution Approach 1:
The invention extracts the compensation function from separate compensation regions or field plates and integrates it directly into the drift region structure itself. By incorporating doping concentration variations directly within the drift region, the patent eliminates the need for additional compensation regions or field plate structures, thereby reducing device complexity while still achieving the desired reduction in on-resistance.
Solution Approach 2:
The invention merges the functions of the drift region and compensation regions into a single integrated structure. The drift region itself is designed with multiple doping concentration zones that perform both the primary drift function and the compensation function simultaneously. This merging eliminates separate compensation structures and simplifies the overall device architecture while maintaining low on-resistance characteristics.
3Reliability
If the base region length is increased to increase voltage blocking capability, then the charge carrier plasma storage increases, but the switching speed decreases
Solution Approach 1:
The invention segments the base region into multiple sections with different doping concentrations, similar to the drift region segmentation. This allows the base region to maintain adequate length for voltage blocking while the differentiated doping concentrations facilitate faster charge carrier removal during switching transitions, thereby improving switching speed without sacrificing voltage blocking capability.
Solution Approach 2:
The invention applies different doping concentrations to different parts of the base region to optimize local properties. Areas of the base region can be designed with specific doping levels to facilitate rapid charge carrier extraction during switching while other areas maintain the structural integrity needed for high voltage blocking, thus resolving the contradiction between switching speed and voltage blocking capability.
Data Source
Figure 1~2B
Figure 3~6B
Figure 7A~9
AI summary
Disclosed is a semiconductor device arrangement including a first semiconductor device having a load path, and a plurality of second transistors, each having a load path between a first and a second load terminal and a control terminal. The second transistors have their load paths connected in series and connected in series to the load path of the first transistor, each of the second transistors has its control terminal connected to the load terminal of one of the other second transistors, and one of the second transistors has its control terminal connected to one of the load terminals of the first semiconductor device.