SOI MOSFET Body Contact Layout for Uniform Body Biasing
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Solution Overview
Problem
Semiconductor devices on silicon-on-insulator (SOI) substrates or deep high resistance layers face performance degradation due to neutral body depletion before source-drain junction punch through, especially in radio frequency (RF) MOSFETs, leading to suboptimal device performance.
Innovation Solution
A semiconductor device design featuring a body contact region spaced apart from a terminal region, with a dielectric layer and an electrically conductive layer in between, and a continuous metallic layer extending to the body contact region for improved body biasing, along with additional spacer elements and interconnects to enhance conductivity and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional transistor structure is used on SOI substrates, then the device can be manufactured with standard processes, but the neutral body depletes easily before source-drain junction punch through occurs, degrading device performance
Solution Approach 1:
The body contact structure is segmented into multiple components: a body contact region, a dielectric layer, an electrically conductive layer, and a continuous metallic layer. This segmentation allows each layer to perform its specific function - the dielectric provides isolation, the conductive layer provides local connectivity, and the metallic layer provides extended body biasing - thereby improving device performance without creating a monolithic complex structure
Solution Approach 2:
The body contact structure extends into the vertical dimension with multiple stacked layers (dielectric layer, electrically conductive layer, continuous metallic layer) rather than relying solely on planar contacts. This vertical stacking enables improved body biasing control and prevents neutral body depletion while maintaining compatibility with standard manufacturing processes
2Reliability
If the body contact region is placed close to the terminal region, then the manufacturing process is simpler, but the body biasing uniformity is poor leading to degraded RF performance
Solution Approach 1:
A dielectric layer is introduced as an intermediary between the body contact region and the terminal region. This dielectric layer enables the body contact region to be spaced apart from the terminal region while still providing proper electrical isolation and body biasing control, thereby improving body biasing uniformity without significantly complicating the fabrication process
Solution Approach 2:
The electrically conductive layer is selectively positioned to provide local connectivity where needed, while the continuous metallic layer provides extended body biasing. This localized quality approach allows the structure to achieve good body biasing uniformity through precise spatial arrangement of conductive elements
Data Source
AI summary
The present disclosure relates to a semiconductor device including a substrate, a first region disposed in the substrate, a terminal region disposed in the first region, a body contact region disposed in the first region and spaced apart from the terminal region, a dielectric layer disposed on the substrate over the first region between the terminal region and the body contact region, an electrically conductive layer disposed on the dielectric layer, and a continuous metallic layer disposed on the electrically conductive layer and extending to the body contact region, the continuous metallic layer disposed on the body contact region and in physical contact with a top and side portions of the electrically conductive layer. The semiconductor device may additionally include a body contact interconnect disposed on a portion of the continuous metallic layer over the electrically conductive layer.