Ridge Body FET Switch for Low On-Resistance and Leakage Control
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Solution Overview
Problem
Power transistors in automotive and industrial electronics require a balance between low on-state resistance and high voltage blocking capability, which existing technologies struggle to achieve effectively, especially in integrated circuits with lateral power devices.
Innovation Solution
A switch comprising a field effect transistor in a semiconductor substrate with a body region shaped as a ridge, where the gate electrode is disposed in gate trenches to control the conductivity of the channel between the source and drain regions, allowing for improved conductivity and reduced leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a lateral power device structure is used to enable integration with driver circuits, then ease of operation and adaptability are improved, but controlling leakage currents and maintaining high voltage blocking capability becomes more difficult
Solution Approach 1:
The drain region is segmented into multiple fingers (first drain region, second drain region) that are spatially separated and independently controlled by respective gate electrodes. This segmentation allows each finger to be optimized for specific functions, enabling better control of leakage currents while maintaining high voltage blocking capability through distributed current paths.
Solution Approach 2:
Different regions of the device are assigned different doping concentrations and structural characteristics. The first drain region has a first doping concentration while the second drain region has a second doping concentration, creating local variations in electrical properties. This allows optimization of specific areas for either low on-state resistance or high voltage blocking, resolving the contradiction between integration capability and reliability.
2Reliability
If the body region is extended in the first direction to reduce short channel effects, then voltage blocking capability is improved, but the device area increases
Solution Approach 1:
The body region is extended primarily in the second direction (perpendicular to the gate length direction) rather than extending in the first direction. This dimensional change allows the effective channel length to be increased for better voltage blocking without proportionally increasing the device area, as the extension occurs in a direction that utilizes available space more efficiently.
Solution Approach 2:
The body region is positioned within the semiconductor substrate in a nested configuration where it extends in the second direction between the source and drain regions. This nesting allows the body region to achieve sufficient length for voltage blocking while being contained within the overall device footprint, minimizing the required device area.
3Reliability
If multiple drain regions are used to reduce leakage currents, then reliability is improved, but device complexity increases
Solution Approach 1:
Multiple drain regions (first drain region and second drain region) are merged into a single integrated structure that functions as one cohesive component. The merged structure shares common elements such as the body region connection and substrate integration, reducing the overall device complexity compared to implementing separate independent drain structures. This merging maintains leakage current control benefits while simplifying the device architecture.
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 solution enables a switch with low on-state resistance and high voltage blocking capability, reducing leakage currents and short channel effects, thus enhancing the performance of power transistors in integrated circuits.
Implementation Method 1
The gate electrode is configured to control a conductivity of a channel formed in the body region
Data Source
AI summary
A switch comprises a field effect transistor in a semiconductor substrate having a first main surface. The field effect transistor comprises a source region, a drain region, a body region, and a gate electrode at the body region, the gate electrode being configured to control a conductivity of a channel formed in the body region. The gate electrode is disposed in gate trenches. The body region is disposed along a first direction between the source region and the drain region, the first direction being parallel to the first main surface. The body region has a shape of a ridge extending along the first direction. The body region is adjacent to the source region and the drain region. The switch further comprises a source contact and a body contact portion, the source contact being electrically connected to a source terminal. The body contact portion is in contact with the source contact and is electrically connected to the body region.