GAA Nanosheet Channel Stack With Thicker Top Sheet
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Solution Overview
Problem
As the minimum feature sizes in semiconductor devices continue to shrink, additional challenges arise in integrating more components into a given area, including issues with reduced channel thickness and increased complexity in manufacturing processes.
Innovation Solution
The development of Gate All-Around (GAA) transistors with a vertical stack configuration, where the topmost channel is thicker than the other channels, allows for improved integration density and manufacturing efficiency by utilizing a multi-layer structure of alternating semiconductor materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If minimum feature sizes are reduced to increase integration density, then more components can be integrated into a given area, but manufacturing complexity and process difficulty increase
Solution Approach 1:
The patent transitions from planar 2D transistor channels to vertical 3D channels extending in the depth direction, allowing integration density improvement without proportionally increasing manufacturing complexity. The vertical channel structure enables more channels to be packed in the same footprint area by utilizing the third dimension.
Solution Approach 2:
The patent divides the vertical channel into multiple discrete channels separated by sacrificial layers, which are selectively removed to create individual vertical channels. This segmentation approach allows precise control over channel formation and simplifies the manufacturing process compared to attempting to create continuous complex structures.
2Quantity of substance
If channel thickness is reduced to increase integration density, then more channels fit in given area, but channel performance and reliability deteriorate
Solution Approach 1:
The patent compensates for reduced channel thickness by extending channels vertically in the depth direction, maintaining adequate channel volume and performance. Multiple thin channels stacked vertically provide sufficient conduction paths while fitting more channels in the planar footprint.
Solution Approach 2:
The patent employs alternating layers of different semiconductor materials (e.g., Si/SiGe) with distinct properties - Si layers form the active channel regions while SiGe layers serve as sacrificial or barrier layers. This composite structure enables precise thickness control and maintains channel performance through material property optimization.
Data Source
AI summary
Semiconductor devices and their manufacturing methods are disclosed herein, and more particularly to semiconductor devices including a transistor having gate all around (GAA) transistor structures and manufacturing methods thereof. Different thickness in an epi-growth scheme is adopted to create different sheet thicknesses within the same device channel regions for use in manufacturing vertically stacked nanostructure (e.g., nanosheet, nanowire, or the like) GAA devices. A GAA device may be formed with a vertical stack of nanostructures in a channel region with a topmost nanostructure of the vertical stack being thicker than the other nanostructures of the vertical stack. Furthermore, an LDD portion of the topmost nanostructure may be formed as the thickest of the nanostructures in the vertical stack.