Cap Layered GAA Gate Structure for Short-Channel Control
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Solution Overview
Problem
Integration of gate-all-around (GAA) transistor structures in semiconductor devices is challenging due to difficulties in fabricating the nanowire gate structure, which affects gate control and increases short-channel effects.
Innovation Solution
A method involving the formation of a semiconductor device structure with a cap layer and multiple metal layers, including a work function layer and spacers, to pattern the GAA transistor structure, reducing parasitic capacitance and enhancing device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fabrication methods are used for GAA transistor structures, then manufacturing simplicity is maintained, but gate control is insufficient and short-channel effects increase
Solution Approach 1:
The gate structure is segmented into multiple components including a first gate structure, a second gate structure, and a third gate structure that are formed at different stages. This segmentation allows each gate component to be independently optimized and formed using appropriate fabrication techniques, improving overall gate control while managing fabrication complexity through staged processing.
Solution Approach 2:
The patent transitions from planar 2D gate structures to three-dimensional gate-all-around structures that wrap around the channel in multiple dimensions. This dimensional change provides superior gate control by enclosing the channel on all sides, though it requires more complex fabrication steps including sacrificial layer formation, spacer deposition, and selective etching.
2Reliability
If GAA transistor structures are integrated, then device performance is enhanced, but fabrication difficulty increases
Solution Approach 1:
Sacrificial layers are formed in advance before the actual gate structures are created. These preliminary sacrificial structures guide the subsequent formation of the gate-all-around features through spacer deposition and selective removal, making the complex GAA fabrication more manageable by establishing a template framework beforehand.
Solution Approach 2:
Spacer layers serve as intermediary elements that bridge the formation of different gate structures. The spacers are deposited conformally on sacrificial layers and then used to define the positions of subsequent gate materials, acting as a mediating structure that simplifies the integration of multiple gate components.
3Reliability
If gate-all-around structure is formed, then short-channel effects are reduced, but manufacturing complexity increases
Solution Approach 1:
The gate structures are nested within each other in a hierarchical arrangement where the first gate structure is formed, then the second gate structure is formed around it, and finally the third gate structure is integrated. This nesting approach allows complex GAA structures to be built systematically from simpler components, reducing short-channel effects through complete channel enclosure while managing structural complexity through ordered assembly.
Data Source
AI summary
A method for forming a semiconductor device structure includes forming nanostructures over a substrate. The method also includes forming a work function layer surrounding the nanostructures. The method also includes forming spacers over opposite sides of the work function layer. The method also includes forming a first metal layer over the work function layer and sidewalls of the spacers. The method also includes forming a second metal layer surrounded by the first metal layer. The method also includes etching the first metal layer over opposite sides of the second metal layer. The method also includes forming a cap layer over a top surface and a sidewall of the second metal layer.