VFET Cross-Shaped Channel Structural Stability
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Solution Overview
Problem
The challenge in forming vertical field-effect transistor (VFET) devices lies in achieving structural stability, particularly during fabrication processes, where existing structures may be prone to collapse, especially when they are tall or stacked.
Innovation Solution
The proposed solution involves a VFET design with a channel region having a cross-shaped upper surface, which includes a core portion and protruding portions along different horizontal directions, providing structural stability and allowing for wider channel width, and the use of a single etch mask layer to form channel regions of various shapes, including cross and line shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional VFET structures are used, then fabrication processes are simpler, but structural stability deteriorates and channel regions may collapse
Solution Approach 1:
The channel region is segmented into multiple protruding portions (first, second, third, and fourth protruding portions) extending in different directions from a core portion. This segmentation creates a cross-shaped configuration that distributes mechanical stress across multiple discrete structural elements, preventing collapse while maintaining overall structural integrity.
Solution Approach 2:
The channel region structure transitions from a conventional planar or single-directional shape to a three-dimensional cross-shaped configuration with protrusions extending in multiple horizontal directions. This dimensional expansion provides additional structural support in multiple orientations, enhancing stability against collapse during fabrication processes.
2Area of moving object
If channel width is increased, then device performance improves, but structural stability deteriorates
Solution Approach 1:
The wide channel region is divided into multiple protruding portions extending in different directions from a core portion. This segmentation allows the channel to achieve a large overall width and area while maintaining structural stability through the distributed configuration of discrete protrusions rather than a single continuous wide structure.
Solution Approach 2:
The channel region utilizes multi-directional protrusions in horizontal directions to achieve increased effective channel width and area. By extending protrusions in multiple directions from the core portion, the structure gains both width and structural reinforcement simultaneously.
3Productivity
If stacked VFETs are formed, then device density improves, but structural stability deteriorates due to increased height
Solution Approach 1:
The channel region is divided into multiple protruding portions that create a cross-shaped configuration. This segmentation provides internal structural support that prevents collapse in tall stacked structures, enabling higher device density through stacking while maintaining stability.
Solution Approach 2:
The cross-shaped channel region with multi-directional protrusions provides enhanced structural support in horizontal directions, which helps stabilize tall vertical stacked structures. This dimensional configuration prevents collapse during fabrication and operation of stacked VFETs.
Data Source
AI summary
Integrated circuit devices and methods of forming the same are provided. Integrated circuit devices may include a vertical field-effect transistor (VFET) that includes a bottom source/drain region in a substrate, a channel region on the bottom source/drain region, a top source/drain region on the channel region, and a gate structure on a side of the channel region. The channel region may have a cross-shaped upper surface.