Traditional methods such as sputtering or evaporation (PVD) are not suitable for deposition and film formation on the surface of 3D complex substrates due to lack of surface control or the existence of sputtered shadow areas. The CVD method requires strict control of the precursor diffusion and the temperature uniformity of the reaction chamber, and it is difficult to meet the requirements of thin film uniformity and precise control of thickness. In contrast, ALD technology is based on surface self-limiting and self-saturating adsorption reactions and has surface control. The bottom surface is deposited to form films, while still ensuring precise sub-monolayer film thickness control.

ALD (Atomic Layer Deposition) and PEALD (Plasma-Enhanced Atomic Layer Deposition) are both surface treatment technologies used for thin film deposition and material processing, and they have some important technical differences and product correlations, as outlined below:

Working Principles:

• ALD: ALD is a method that involves alternating reactions of gas-phase precursors, typically conducted in a vacuum or nitrogen atmosphere. Each layer of precursor undergoes independent adsorption and reaction to form an atomic-thin film on the surface.

• PEALD: PEALD is a variation of ALD that introduces a plasma source. By introducing precursors into the plasma, reaction rates can be increased, making it suitable for higher deposition rates and certain special applications.

Applications:

• ALD: ALD is commonly used for fabricating high-quality, highly uniform thin films, such as metal oxides, nitrides, and sulfides, used in fields such as transistors, solar cells, integrated circuits, and more.

• PEALD: The higher deposition rates and special chemical reactivity of PEALD make it suitable for growing films that are challenging to achieve in traditional ALD, such as silicon nitride, silicon carbide, and other non-oxide films.

Technical Differences:

• Plasma Source: PEALD incorporates a plasma source, typically RF (Radio Frequency) or microwave plasma, to activate precursors and enhance reaction rates.

• Deposition Rate: PEALD typically has higher deposition rates compared to traditional ALD, which is important for large-scale production and certain rapid growth applications.

• Material Range: PEALD is more amenable to growing certain non-oxide films because the plasma provides more activation energy and reactivity.

In summary, ALD and PEALD are related but distinct surface treatment technologies with different advantages in terms of thin film deposition applications and technical characteristics. The choice of which technology to use depends on specific application requirements, including the desired thin film material, deposition rate, and film quality.