What Is The Purpose Of Employing Ozone (O3) Treatment Following The As-Ald Of Al2O3? Boost Film Purity And Density

Ozone (O3) treatment serves as a vital purification and densification step immediately following the Area-Selective Atomic Layer Deposition (AS-ALD) of Aluminum Oxide (Al2O3). Its primary purpose is to act as a highly reactive oxidant that drives the ALD reaction to completion while simultaneously stripping away specific residual organic inhibitors.

Core Takeaway Ozone acts as a "chemical scrubber" that eliminates persistent organic ligands—specifically cyclopentadienyl (Cp) groups—from the substrate surface. This process converts the deposited precursor material into a dense, high-quality oxide film, ensuring a pristine interface for the subsequent integration of materials like Zirconia (ZrO2).

The Dual Mechanism of Ozone Treatment

Eliminating Residual Inhibitors

Area-Selective ALD relies on inhibitors to prevent growth on specific surfaces, but these organic molecules can linger where they are no longer wanted.

Ozone functions as a powerful cleaning agent in this context. It aggressively oxidizes and removes residual inhibitor ligands, such as cyclopentadienyl (Cp) groups, that remain on the surface after the initial deposition.

Driving Film Densification

Beyond simple cleaning, the chemical nature of the film must be finalized to ensure stability.

The oxidative action of O3 converts the deposited aluminum material into a fully oxidized, dense Al2O3 film. This ensures the material properties are consistent and free from organic defects that could compromise performance.

Importance for Multilayer Stacks

Creating a Clean Interface

The quality of a multi-material stack depends heavily on the boundary between layers.

By thoroughly eliminating organic contaminants, ozone treatment creates a chemically clean surface. This is specifically required to prepare the interface for the deposition of a top Zirconia (ZrO2) layer.

Ensuring Adhesion and Continuity

If residual ligands are left on the surface, they can interfere with the nucleation of the next layer.

Ozone treatment prevents this issue by exposing a reactive oxide surface. This facilitates the uniform and adhesive growth of the subsequent ZrO2 film.

The Risks of Omission

Understanding Organic Contamination

Skipping the ozone step poses a significant risk to the structural integrity of the device.

Without this strong oxidative step, organic ligands (Cp groups) become trapped within or between layers. This leads to a lower density film with poor dielectric properties and a "dirty" interface that degrades the performance of the final film stack.

Making the Right Choice for Your Goal

To optimize your AS-ALD process, align the use of ozone with your specific fabrication requirements:

If your primary focus is Film Purity: Utilize ozone treatment to aggressively oxidize and volatilize residual cyclopentadienyl (Cp) ligands that standard purging cannot remove.
If your primary focus is Multilayer Integration: Employ ozone treatment to densify the Al2O3 surface immediately before depositing Zirconia (ZrO2) to ensure a defect-free interface.

Treating the surface with ozone is not merely an optional cleaning step; it is a fundamental requirement for transforming a precursor deposition into a functional, high-quality oxide interface.

Summary Table:

Feature	Purpose of Ozone (O3) Treatment in AS-ALD
Function	Acts as a powerful chemical scrubber and reactive oxidant
Contaminant Removal	Strips residual organic inhibitors (e.g., cyclopentadienyl groups)
Film Quality	Converts precursor material into a dense, high-quality Al2O3 film
Interface Prep	Creates a pristine surface for subsequent ZrO2 layer integration
Risk Mitigation	Prevents trapped organic defects and poor dielectric properties

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References

Moo‐Yong Rhee, Il‐Kwon Oh. Area‐Selective Atomic Layer Deposition on Homogeneous Substrate for Next‐Generation Electronic Devices. DOI: 10.1002/advs.202414483

This article is also based on technical information from Kintek Furnace Knowledge Base .