Staggered Body Contacts for SOI Floating Body Suppression
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Solution Overview
Problem
Semiconductor-on-insulator (SOI) technologies face challenges with variable body resistance due to finite epi-silicon layer thickness, leading to floating body effects that affect device linearity and breakdown voltage in body-contacted devices.
Innovation Solution
The implementation of staggered body contacts along the width of the gate structure, isolated by shallow trench isolation structures, allows for independent biasing and optimizes device performance by reducing the floating body effect and increasing breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If well doping is reduced to increase diode saturation current, then the device becomes more fully depleted and built-in potential of the surface barrier junction is reduced, but Ioff increases
Solution Approach 1:
The patent applies local quality by creating non-uniform doping profiles in specific regions. The gradient doping in the body region and selective doping near body contacts provide localized electrical properties that differ from the bulk, enabling reduced well doping overall while maintaining adequate carrier control and preventing excessive Ioff through localized field management.
Solution Approach 2:
The patent changes physical parameters including doping concentration gradients, body contact spacing, and contact depth. By varying these parameters spatially and optimizing their combinations, the device achieves improved linearity through better depletion control while managing Ioff through optimized carrier generation and recombination characteristics.
2Reliability
If well doping is increased to make a perfect conductor at high Vd, then body resistance is reduced, but Vth increases very high and the device may not turn on
Solution Approach 1:
The patent uses local quality by implementing non-uniform doping profiles where high doping concentrations are localized near body contacts and in specific regions to reduce resistance where needed, while other regions maintain lower doping to preserve threshold voltage characteristics and ensure proper device turn-on behavior.
Solution Approach 2:
The patent transitions from uniform bulk doping to spatially varying doping profiles that consider three-dimensional positioning. By optimizing doping in the vertical and lateral dimensions separately, the device achieves low resistance paths where required while maintaining adequate Vth through controlled doping in channel-forming regions.
3Reliability
If pre-amorphization implants are introduced into the body region, then generated minority carriers are eliminated and the kink may be reduced, but not for all Vg regimes
Solution Approach 1:
The patent applies local quality by implementing pre-amorphization implants in specific body region locations and at specific depths rather than uniformly throughout. This localized approach eliminates minority carriers in critical regions to reduce kinks while preserving carrier generation in other regions, thereby maintaining effectiveness across broader Vg regimes.
4Reliability
If staggered body contacts are implemented, then floating body effects are reduced and breakdown voltage is increased, but device structure and fabrication complexity increase
Solution Approach 1:
The patent applies segmentation by dividing the body contact structure into multiple staggered contacts rather than a single continuous contact. This segmentation creates isolated contact regions that effectively reduce floating body effects by limiting carrier accumulation zones, while the modular nature of segmented contacts facilitates systematic fabrication processes.
Solution Approach 2:
The patent employs asymmetry through the staggered positioning of body contacts at different locations and depths. This asymmetric configuration optimizes electrical field distribution and carrier collection efficiency, reducing floating body effects while the systematic asymmetric pattern can be integrated into existing fabrication workflows.
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to devices with staggered body contacts and methods of manufacture. The device includes: a gate structure on a semiconductor substrate material, the gate structure comprising a gate body with a width and a length; a plurality of body contacts electrically contacting a channel region under the gate body on at least one side of the gate body along its width; and isolation structures isolating the plurality of body contacts from a source region and a drain region associated with the gate structure.