Non-floating Vertical Transistor Segregating Pillar
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Solution Overview
Problem
The floating body effect in semiconductor devices causes threshold voltage shift, leading to abnormal device operation, which existing technologies have not effectively addressed.
Innovation Solution
A non-floating vertical transistor structure is introduced, featuring segregated bit-lines separated by a segregating pillar of a different dopant type, which mitigates the threshold voltage shift by electrically isolating word-lines and stabilizing the channel region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional vertical transistor structure is used, then the device can be manufactured with standard processes, but the floating body effect causes threshold voltage shift and abnormal operation
Solution Approach 1:
The bit-line is divided into two separate segments (first bit-line and second bit-line) that are physically separated by the isolating pillar. This segmentation prevents the floating body effect by creating distinct electrical paths for electrons and holes, eliminating the charge accumulation that causes threshold voltage shift while maintaining manageable structural complexity
Solution Approach 2:
An isolating pillar is introduced as an intermediary structure between the first and second bit-lines. This pillar, extending from the substrate to the gate electrode, acts as a physical and electrical barrier that separates the n-type and p-type doped regions, preventing harmful charge accumulation while allowing the gate to control both channels independently
2Manufacturing precision
If the bit-line is electrically connected without separation, then the manufacturing process is simpler, but the threshold voltage shifts due to charge accumulation in the body
Solution Approach 1:
The isolating pillar is strategically positioned only in the critical region where the bit-line contacts the substrate and channel region. This localized separation provides precise threshold voltage control by preventing charge accumulation at the source, while the rest of the transistor structure maintains standard fabrication compatibility
Solution Approach 2:
The isolating pillar is formed with a composite structure comprising an insulating material core surrounded by a doped semiconductor shell. This composite design provides both electrical isolation and mechanical integration with the surrounding transistor structures, enabling precise manufacturing control through standard semiconductor processing techniques
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 reduces threshold voltage shift, enhancing the operational stability and reliability of semiconductor devices by electrically segregating the channel region and maintaining consistent device performance.
Implementation Method 1
a segregating pillar which is constructed by a different dopant type in the non-floating vertical transistor structure. The pair is adjacent to the bottom of the segregating pillar, segregated by the segregating pillar
Data Source
AI summary
A non-floating vertical transistor includes a substrate and a protuberant structure extending from the substrate. A segregating pillar is inside the protuberant structure. A pair of segregated bit-lines which are segregated by the segregating pillar is disposed in the substrate and in the protuberant structure and adjacent to the bottom of the segregating pillar. A gate oxide layer is attached to the sidewall of the protuberant structure. A word-line is adjacent to the gate oxide layer so that the gate oxide layer is sandwiched between the word-line and a doped deposition layer.