Semiconductor Transistor Field Plate Drift Zone Configuration
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Solution Overview
Problem
Power transistors in automotive, industrial, and consumer electronics require low on-state resistance while maintaining high voltage blocking capability, and existing designs aim to further reduce on-state resistance.
Innovation Solution
The semiconductor device incorporates a transistor with a drift zone of a first conductivity type, adjacent to a drain region, and multiple field plates arranged at different distances and connected to contact portions within the drift zone, allowing for increased doping concentration and reduced on-state resistance by managing the electrical field and potential differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the doping concentration in the drift zone is increased to reduce on-state resistance, then the on-state resistance decreases, but the voltage blocking capability deteriorates
Solution Approach 1:
The drift zone is divided into multiple regions with different doping concentrations: a first drift zone region with higher doping concentration (adjacent to source/drain) to reduce on-state resistance, and a second drift zone region with lower doping concentration (in the middle) to maintain voltage blocking capability. This local differentiation allows each region to optimize for its specific function.
Solution Approach 2:
The drift zone is segmented into multiple regions along the current flow direction, with each region having distinct doping characteristics. The segmentation allows the device to simultaneously achieve low on-state resistance in high-current regions and high breakdown voltage in low-stress regions.
2Reliability
If the drift zone width is increased to maintain voltage blocking capability, then the voltage blocking capability improves, but the on-state resistance increases
Solution Approach 1:
Different regions of the drift zone have different doping concentrations optimized for their specific locations: higher doping near source/drain for low resistance, lower doping in the middle for high breakdown voltage, allowing the entire drift zone to achieve both low on-state resistance and high voltage blocking capability without increasing overall width.
Solution Approach 2:
The doping concentration parameter is varied along the length of the drift zone, creating a gradient or stepped profile. This parameter change allows the drift zone to simultaneously exhibit properties suitable for both low resistance (high doping) and high breakdown voltage (low doping) without compromising either performance metric.
3Reliability
If multiple field plates are added to manage electrical field distribution, then the electrical field management improves, but the device complexity increases
Solution Approach 1:
The field plate structure is segmented into multiple sections positioned over different regions of the drift zone, with each segment controlled by separate contacts. This segmentation allows independent optimization of the electrical field in different regions, improving overall field distribution while maintaining manageable complexity through modular design.
Solution Approach 2:
The field plates serve multiple functions: they shape the electrical field distribution, protect the drift zone from high electric fields, and can be used to control the breakdown characteristics. This multi-functionality reduces the need for additional separate structures, managing complexity while achieving reliable electrical field management.
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 configuration reduces on-state resistance and increases the effective width of the drift zone, enhancing the transistor's performance in conducting high currents while maintaining voltage blocking capabilities.
Implementation Method 1
multiple field plates arranged at different distances and connected to contact portions within the drift zone, allowing for increased doping concentration and reduced on-state resistance by managing the electrical field and potential differences
Implementation Method 2
a drift zone of a first conductivity type, adjacent to a drain region... increasing the doping concentration in the drift zone and/or in a portion of the drift zone adjacent to the source region and to the drain region
Data Source
AI summary
A semiconductor device includes a transistor in a semiconductor substrate. The transistor includes a drift zone of a first conductivity type adjacent to a drain region, and a first field plate and a second field plate adjacent to the drift zone. The second field plate is arranged between the first field plate and the drain region. The second field plate is electrically connected to a contact portion arranged in the drift zone. The transistor further includes an intermediate portion of the first conductivity type at a lower doping concentration than the drift zone. A distance between the intermediate portion and the drain region is smaller than the distance between the contact portion and the drain region.