Gate Stack-Wrapped Fin Structures for Precise GAA Fabrication
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Solution Overview
Problem
The challenge of forming reliable semiconductor devices at smaller sizes is exacerbated by the complexity of fabrication processes as feature sizes continue to decrease, particularly in the development of FinFETs and gate all around (GAA) transistor structures.
Innovation Solution
A method involving double-patterning or multi-patterning processes is used to create gate all around (GAA) transistor structures, utilizing sacrificial layers and self-aligned processes to form precise patterns, followed by the formation of gate stacks and spacers, and the use of epitaxial growth to form semiconductor layers with controlled crystal orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature sizes continue to decrease to increase functional density, then production efficiency improves and costs lower, but fabrication process complexity increases and manufacturing reliability becomes more difficult to maintain
Solution Approach 1:
The fabrication process is divided into multiple self-aligned patterning steps, where each step creates a portion of the final pattern using sacrificial layers and spacer formation. This segmentation allows complex patterns to be built systematically, reducing the difficulty of single-step fabrication while maintaining high functional density
Solution Approach 2:
Sacrificial layers are deposited and patterned in advance to define the positions of subsequent features. These preliminary structures guide the formation of spacers and final patterns, simplifying the overall fabrication process by breaking down complex patterning into manageable preliminary steps
2Productivity
If feature sizes continue to decrease, then functional density increases, but manufacturing precision becomes more difficult to achieve
Solution Approach 1:
The process uses self-aligned spacer formation where the spacer material automatically defines the position of subsequent features based on the sacrificial layer geometry. This self-alignment mechanism eliminates the need for additional lithography alignment steps, maintaining manufacturing precision even as feature sizes decrease
Solution Approach 2:
Sacrificial layers serve as intermediary structures that are deposited, patterned, and then removed to create spaces for spacer formation. These intermediary structures enable precise pattern definition without requiring direct lithography of the final pattern, thereby maintaining precision at smaller feature sizes
3Productivity
If gate all around (GAA) transistor structures are used to improve gate control efficiency, then operational efficiency increases, but fabrication process complexity increases
Solution Approach 1:
The GAA transistor structure embeds multiple fin structures within a hierarchical arrangement, with gate stacks wrapped around each fin. This nested configuration achieves three-dimensional gate control that improves operational efficiency while the systematic formation process using self-aligned patterning keeps fabrication complexity manageable
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
This approach enables the fabrication of reliable semiconductor devices with improved gate control over the transistor channel, enhancing operational efficiency and reducing fabrication complexities at smaller scales.
Implementation Method 1
The undoped semiconductor layer separates the doped layer from the isolation structure, which prevents the dopants in the doped layer from diffusing into the isolation structure
Data Source
AI summary
A semiconductor device structure is provided. The semiconductor device structure includes a substrate having a base and a fin structure over the base. The fin structure includes a lower portion, a first nanostructure, and a second nanostructure, and the first nanostructure is between the lower portion and the second nanostructure. The semiconductor device structure includes an isolation structure over the base and surrounding the lower portion. The semiconductor device structure includes a gate stack wrapped around an upper portion of the fin structure. The semiconductor device structure includes a source/drain structure partially embedded in the isolation structure and the lower portion of the fin structure.