Vertical GAA FET Body Contact for Floating-Body Suppression
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Solution Overview
Problem
Fully depleted vertical FETs suffer from a floating-body effect, leading to threshold voltage shifts and increased off-current, which is difficult to mitigate without compromising device performance due to the challenges in manufacturing high-quality body contacts.
Innovation Solution
A gate-all-around or multi-gate vertical semiconductor device with a body contact is developed, featuring a first and second gate stack on opposite sides of the active region, with a body contact layer applied to suppress the floating-body effect and enhance gate control by applying a body bias.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a body contact is added to suppress floating-body effects, then threshold voltage stability is improved, but channel thickness increases and short channel control deteriorates
Solution Approach 1:
The device is segmented into multiple functional regions: a first region with a first gate electrode for primary gate control, and a second region with a second gate electrode for body bias control. The body contact is separated from the main channel region, allowing independent optimization of threshold voltage stability and short channel control in different segments of the device.
Solution Approach 2:
An isolation layer is introduced as an intermediary between the body contact region and the channel region. This isolation layer electrically couples the body contact to the channel for bias control while physically separating the body contact structure from the main channel, thereby maintaining short channel control performance while achieving threshold voltage stabilization.
2Length of moving object
If vertical FET structure is adopted for miniaturization, then device scaling is improved, but floating-body effects increase causing threshold voltage shifts and off current increase
Solution Approach 1:
The vertical FET is divided into multiple functional regions along the vertical direction: a first region for primary gate control and a second region for body bias control. This segmentation allows the device to maintain miniaturization benefits while independently addressing floating-body effects through the separate body bias control region.
Solution Approach 2:
The invention changes the electrical parameters by introducing a body bias control mechanism that can independently adjust the potential in the second region. This parameter change allows suppression of floating-body effects through controlled potential distribution, enabling threshold voltage stabilization in the miniaturized vertical structure.
3Reliability
If gate-all-around structure is implemented, then gate control is improved, but manufacturing complexity increases
Solution Approach 1:
The gate structure is segmented into a first gate electrode and a second gate electrode positioned at different vertical regions. This segmentation simplifies the manufacturing process by allowing separate formation and optimization of each gate electrode, while still achieving comprehensive gate control through the combined action of both gates.
Solution Approach 2:
Instead of a single planar gate, the invention extends gate control into the vertical dimension with the second gate electrode positioned in the second region above the body contact. This dimensional extension improves gate control effectiveness without requiring complex three-dimensional gate structures, thereby reducing manufacturing complexity.
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 effectively suppresses the floating-body effect, improves gate control, and enhances device performance by optimizing on-current and threshold voltage adjustment, while maintaining accurate channel region thickness and doping characteristics.
Implementation Method 1
a body contact layer disposed on the second side of the active region to overlap a part of the middle portion of the active region, so as to apply a body bias to the active region
Implementation Method 2
a first gate stack and a second gate stack, wherein the first gate stack and the second gate stack are disposed on a first side of the active region and a second side of the active region
Data Source
AI summary
Provided are a vertical semiconductor device with a body contact, a manufacturing method, and an electronic apparatus. The semiconductor device includes: an active region vertically disposed on a substrate relative to the substrate, including lower and upper source/drain regions, and a middle portion between the lower and upper source/drain regions for defining a channel region; first and second gate stacks which are disposed on first and second sides of the active region which are opposite to each other in a lateral direction relative to the substrate; and a body contact layer disposed on the second side of the active region to overlap a part of the middle portion of the active region, so as to apply a body bias to the active region, wherein the second gate stack includes first and second portions below and above the body contact layer respectively.