GAA Nanostructure Hard Mask Layout for Planarization Control
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Solution Overview
Problem
In the manufacturing of gate-all-around (GAA) field effect transistors, the over-etching of hard mask layers during planarization can damage the silicon-based structure, leading to reduced efficiency and increased resource wastage, while insufficient etching leaves residual material that interferes with subsequent operations, causing semiconductor device failures.
Innovation Solution
A method is employed to form a semiconductor device by depositing a silicon-based structure with alternating layers, using a first and second hard mask layer, followed by a cladding structure, and then performing a planarization operation to remove dielectric material. This method involves removing a top portion of the cladding structure before the second hard mask layer, reducing the height difference and minimizing over-etching, thereby preserving the silicon-based structure and enhancing manufacturing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If planarization operation is performed to remove dielectric material, then manufacturing precision is improved, but the silicon-based structure may be damaged due to over-etching
Solution Approach 1:
The patent divides the cladding structure into multiple segments with different heights (first cladding structure at higher elevation, second cladding structure at lower elevation). This segmentation allows the planarization operation to selectively remove dielectric material down to the first hard mask layer without exposing or damaging the silicon-based structure, as the lower cladding structure provides a protective barrier. The segmented approach enables precise control of etching depth while maintaining manufacturing precision.
Solution Approach 2:
The patent performs preliminary actions by forming the first and second cladding structures with different heights before the planarization operation. The second cladding structure is intentionally formed at a lower elevation to serve as a pre-established protective barrier. This preliminary configuration ensures that when planarization is subsequently performed, the etching process stops at the desired depth (first hard mask layer) without risking damage to the silicon-based structure, as the lower cladding structure is already in place to prevent over-etching.
2Manufacturing precision
If etching is performed to remove hard mask layers, then manufacturing precision is improved, but residual material remains if etching is insufficient
Solution Approach 1:
The patent segments the hard mask configuration into multiple layers (first hard mask layer and second hard mask layer) with different elevations. The second hard mask layer is positioned at a higher elevation than the first. This segmentation allows the planarization process to selectively remove dielectric material and expose the first hard mask layer while leaving the second hard mask layer intact. The segmented structure ensures complete removal of necessary materials without leaving residual hard mask material that would interfere with subsequent operations, thereby maintaining both precision and reliability.
Solution Approach 2:
The patent applies local quality by creating regions with different hard mask layer configurations. The first hard mask layer is exposed in certain regions after planarization, while the second hard mask layer remains in other regions. This local differentiation allows precise control over where etching occurs and where protection is maintained, ensuring that residual material does not remain in critical areas while preserving necessary hard mask structures in other areas for subsequent processing steps.
3Manufacturing precision
If multiple hard mask layers are used, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent uses segmentation of the cladding structure into first and second cladding structures with different heights, which corresponds to the segmentation of hard mask layers. The first cladding structure protects the first hard mask layer, while the second cladding structure protects the second hard mask layer. This segmented approach provides precise process control during planarization and etching operations, allowing selective exposure and removal of materials. Although the structure is more complex than a single-layer configuration, the segmentation enables the precise multi-step manufacturing process required for GAA FET fabrication, where different regions require different processing conditions.
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 increases the process window for forming semiconductor devices, reduces defects, and conserves resources by minimizing damage to the silicon-based structure and residual material interference, resulting in improved efficiency and reduced failure likelihood.
Implementation Method 1
depositing a silicon-based structure with alternating layers
Implementation Method 2
performing a planarization operation to remove dielectric material
Data Source
AI summary
Implementations described herein provide a method of forming a semiconductor device. The method includes forming a nanostructure having a first set of layers of a first material and a second set of layers, alternating with the first set of layers, having a second material. The method further includes depositing a hard mask on a top layer of the first set of layers, the hard mask including a first hard mask layer on the top layer of the first set of layers and a second hard mask layer on the first hard mask layer. The method also includes depositing elements of a cladding structure on sidewalls of the nanostructure and the hard mask. The method further includes removing a top portion of the cladding structure. The method further includes removing the second hard mask layer after removing the top portion of the cladding structure.