Selective Silicon Nitride Deposition on Stepped Structures
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Solution Overview
Problem
Existing methods for forming thin films on stepped structures in semiconductor devices, such as 3D semiconductor devices, face challenges in selectively depositing films on upper and lower surfaces without etching the side surfaces, which can lead to signal interference and require complex photolithography processes.
Innovation Solution
A method involving the sequential deposition of silicon nitride layers using plasma-enhanced atomic layer deposition (PEALD), followed by asymmetric plasma treatment and wet etching, allows for selective film formation on upper and lower surfaces while minimizing etching on side surfaces, thereby preventing signal interference and eliminating the need for photolithography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional thin film deposition is performed on stepped structures, then complete coverage is achieved, but side surfaces are etched leading to signal interference
Solution Approach 1:
The patent applies local quality by creating different surface properties in different regions of the stepped structure. The upper and lower surfaces are made hydrophilic through oxygen plasma treatment, while side surfaces remain hydrophobic. This allows selective deposition of water-based slurry only on upper and lower surfaces, preventing side surface etching and the associated signal interference problems.
Solution Approach 2:
The patent uses preliminary action by performing surface treatment (oxygen plasma exposure) before the deposition process. This pre-treatment modifies the surface energy characteristics of specific regions, ensuring that subsequent water-based slurry deposition occurs only on predetermined areas (upper and lower surfaces) while excluding side surfaces, thereby avoiding signal interference.
2Manufacturing precision
If photolithography is used to achieve selective deposition, then precision is improved, but process complexity increases
Solution Approach 1:
The patent replaces the mechanical/chemical photolithography system with a surface energy-based selective deposition system. Instead of using photoresist materials, masks, and complex alignment processes, the invention uses oxygen plasma treatment to create hydrophilic regions that selectively attract water-based slurry through capillary action and surface energy differences, eliminating the need for photolithography entirely.
Solution Approach 2:
The patent changes the fundamental parameter controlling deposition from optical absorption (in photolithography) to surface energy/hydrophilicity. By exposing surfaces to oxygen plasma, the surface energy is modified to create hydrophilic regions, and by controlling slurry composition and deposition conditions, selective filling is achieved based on surface energy differences rather than optical patterning, simplifying the overall process.
3Productivity
If uniform etching is applied to sacrificial structures, then removal is complete, but landing pad integrity is compromised
Solution Approach 1:
The patent applies local quality by creating different etch resistance characteristics in different regions of the sacrificial structure. The landing pad region is treated to have enhanced etch resistance (through additional silicon nitride layers or modified composition), while other sacrificial regions maintain standard etchability. This allows the etching process to proceed at high speed in non-critical areas while protecting the landing pad region from over-etching, maintaining both productivity and precision.
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 efficient formation of conductive word lines with controlled etch rates and sidewall profiles, enhancing the isolation between word lines and reducing the complexity of the manufacturing process.
Implementation Method 1
forming a first silicon nitride layer, a second silicon nitride layer, and a third silicon nitride layer on the substrate through plasma enhanced atomic layer deposition
Implementation Method 2
densifying the third silicon nitride layer through asymmetric plasma treatment
Implementation Method 3
wet-etching at least a portion of the sacrificial word line structure including the first silicon nitride layer, the second silicon nitride layer, and the third silicon nitride layer
Data Source
AI summary
A method of processing a substrate by omitting a photolithographic process is disclosed. The method includes forming at least one layer on a stepped structure having an upper surface, a lower surface, and a side surface that connects the upper surface to the lower surface, selectively densifying portions of the at least one layer respectively on the upper surface and the lower surface via asymmetric plasma application, and performing an isotropic etching process on the at least one layer. During the isotropic etching process, the portion of the at least one layer formed on the upper surface is separated from the portion of the at least one layer formed on the lower surface.