FET With Separate Source Body Contacts
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Solution Overview
Problem
Existing field effect transistor designs face challenges in achieving small cell sizes while allowing for the application of different electric potentials to the source and body regions, which is necessary in some integrated circuit designs.
Innovation Solution
A field effect transistor device with a semiconductor substrate featuring a body well of one type of conductivity, a source region of opposite conductivity, and a body contact region of the same conductivity, where a portion of the gate electrode layer is between the source and body contacts, and spacers are used to prevent silicide formation under these regions, allowing for separate contacts and reduced cell size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If source and body are provided with a common contact, then cell size is reduced, but different voltages cannot be applied to source and body
Solution Approach 1:
The contact structure is segmented into separate source contact and body contact regions, allowing independent voltage application to source and body while maintaining compact cell size through optimized spatial arrangement of these segmented contact regions
Solution Approach 2:
The gate electrode layer is positioned in a third dimension (vertically) between the source contact and body contact regions, enabling separate contacts without increasing planar cell footprint by utilizing vertical gating structure to achieve contact separation
2Adaptability or versatility
If separate source and body contacts are used, then different voltages can be applied to source and body, but cell size increases
Solution Approach 1:
The source contact and body contact regions are merged into a unified contact structure design that shares common fabrication steps and spatial organization, reducing overall cell size while maintaining separate electrical connections to source and body regions
3Reliability
If spacers are used to prevent silicide formation, then device reliability is improved, but manufacturing complexity increases
Solution Approach 1:
Silicide prevention spacers are formed preliminarily before silicide deposition, pre-positioning protective structures in critical areas to prevent unwanted silicide formation, thereby improving device reliability while managing manufacturing complexity through strategic timing of spacer formation in the fabrication sequence
Data Source
Figure 1
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Figure 4
AI summary
The field effect transistor device comprises a substrate (1) of semiconductor material, a body well of a first type of electric conductivity in the substrate, a source region in the body well, the source region having an opposite second type of electric conductivity, a source contact (3) on the source region, a body contact region of the first type of electric conductivity in the body well, a body contact (5) on the body contact region, and a gate electrode layer (2) partially overlapping the body well. A portion (2*) of the gate electrode layer (2) is present between the source contact (3) and the body contact (5).