MOSFET Body Structure for UIS Robustness and Electric Field Control
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Solution Overview
Problem
MOSFET transistors face destruction due to high reverse current during unclamped inductive switching (UIS) tests, which activates the parasitic bipolar transistor.
Innovation Solution
The MOSFET transistor features a body structure with a body region and a strengthening region, along with an enriched region, which reduces the risk of parasitic bipolar transistor activation by managing the current flow effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the MOSFET transistor operates with inductive-type load, then the MOSFET transistor can handle high voltage, but the parasitic bipolar transistor may be turned on due to high reverse current, causing destruction
Solution Approach 1:
The body region is segmented into multiple body structures, each comprising a body region and an enriched region. This segmentation allows the electric field to be distributed and controlled within each segment, preventing the formation of high electric field regions that would activate the parasitic bipolar transistor while maintaining overall voltage blocking capability.
Solution Approach 2:
The enriched region is introduced with specific doping characteristics (different doping type and/or concentration) to create localized electric field control. This local quality modification enables precise control of the electric field distribution at critical interfaces, particularly at the drain-side interface, to prevent parasitic bipolar transistor activation.
2Ease of manufacture
If the body region structure is simplified, then the manufacturing process is easier, but the electric field control and charge injection management are insufficient
Solution Approach 1:
The enriched region is formed during the manufacturing process at a predetermined location and with predetermined doping characteristics. This preliminary action establishes the desired electric field distribution profile before device operation, ensuring proper electric field control and charge injection management without requiring complex post-fabrication adjustments.
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 design enhances the robustness of the MOSFET transistor by reducing the electric field below the gate dielectric regions, minimizing charge injection, and decreasing energy dissipation, thereby improving switching efficiency.
Implementation Method 1
The body structure (20) includes an enriched region (23), which has a doping level greater than the doping level of the body region (22)
Data Source
AI summary
A MOSFET transistor with a semiconductor body including a drain region of a first conductivity type, delimited by a front surface, and at least one cell including: a pair of gate structures laterally offset parallel to a first axis and each including a respective gate dielectric region, arranged on the front surface, and a respective gate conductive region, arranged on the corresponding gate dielectric region; a body structure of a second conductivity type, which includes a body region, which extends inside the drain region starting from the front surface and contacts portions of the gate dielectric regions, and a strengthening region, which extends below the body region; and a pair of source regions of the first conductivity type, which extend inside the body region starting from the front surface. The body structure includes an enriched region, which extends inside the body region, below the source regions, and protrudes laterally, parallel to the first axis, in both directions with respect to the pair of source regions.