As semiconductor processes continue to advance toward extreme miniaturization and high integration, the operational environments that process equipment must endure are becoming increasingly harsh. In particular, during the etching process, high-energy plasma and reactive ions continuously erode the inner walls and components of the equipment. This erosion poses a serious threat to both the equipment's lifespan and the stability of the process itself. Under such extreme conditions, one of the most promising technologies for protecting critical components is APS (Atmospheric Plasma Spray) coating based on YAG material.
■ Why YAG? — Overcoming the Limits of Y₂O₃ and Al₂O₃
APS (Atmospheric Plasma Spray) coating is a technology that melts ceramic powders using a plasma heat source and rapidly sprays them onto equipment surfaces to form a durable protective layer. The performance of the coating varies significantly depending on which ceramic material is used. In this regard, YAG has emerged as a next-generation material that surpasses the limitations of conventional Y₂O₃ and Al₂O₃ coatings.
| Category | Y₂O₃ (Yttria) | Al₂O₃ (Alumina) | YAG (Yttrium Aluminum Garnet) |
| Plasma Corrosion Resistance | Excellent (Stable in F⁻ environment) |
Moderate (Gradually eroded by F⁻) |
Excellent (Stable even under prolonged exposure) |
| Mechanical Strength | Moderate | High | High (Highly resistant to repeated impact) |
| Thermal Expansion Coefficient | Low | Low | Low (Outstanding thermal shock resistance) |
| Melting Point | ~2,425°C | ~2,050°C | ~1,940°C (Lowest, thus easier to melt) |
| Coating Adhesion | Moderate (Some porosity present) |
High | High (Forms dense microstructure) |
| Particle Generation Suppression | Stabilizes after seasoning | Potential for particle generation | Minimizes particle generation |
| Applicable Processes | Primarily for Etching | Basic Etch/Deposition components | High-precision Etch components (e.g., ESC, rings, etc.) |
Traditionally, Al₂O₃ (Alumina) has been widely used for its excellent mechanical strength and insulating properties. However, it exhibits limited corrosion resistance in plasma environments containing fluorine (F⁻) or chlorine (Cl⁻), making it vulnerable to chemical attack. In contrast, Y₂O₃ (Yttria) offers superior plasma corrosion resistance but suffers from relatively low hardness and thermal shock resistance, often leading to issues such as cracking or delamination during repeated processing.
To overcome these limitations and combine the advantages of both materials, YAG (Yttrium Aluminum Garnet, Y₃Al₅O₁₂) has emerged as a high-performance ceramic material. YAG is not just a simple composite; it is a next-generation material engineered with structural strengths that are highly optimized for protecting semiconductor equipment components. This is especially critical in etching processes, where plasma repeatedly interacts with surfaces—meaning that the durability and chemical stability of the coating material are directly linked to yield performance. In this context, YAG stands out as a key solution for achieving process stability.
YAG demonstrates excellent plasma corrosion resistance, significantly slowing down the erosion rate of the coating layer. Its high mechanical strength enables it to withstand prolonged and repeated processing cycles without cracking or delaminating. Furthermore, due to its low thermal expansion coefficient, it resists deformation even under sudden temperature changes, thereby enhancing the thermal stability of the coating.
From a processing standpoint, YAG also offers advantages in the APS (Atmospheric Plasma Spray) coating method. Compared to Y₂O₃, YAG has a lower melting point, allowing for more complete melting during spraying. This results in a denser, more adherent, and uniform coating layer with fewer voids. The practical benefits include reduced particle generation, shorter seasoning times, and increased equipment uptime—ultimately supporting high-yield, high-reliability semiconductor manufacturing.
■ APS-UC2™: Advanced Coating Specialized for Corrosion and Plasma Resistance
Through its own proprietary R&D, KoMiCo has developed a premium APS coating solution known as UC2™ Coating (Ultra Concentrated Coating). UC2™ is a next-generation APS coating technology that applies a YAG-based material with a special crystalline structure and precision particle control techniques. It offers significantly enhanced durability and plasma resistance, surpassing the limitations of traditional Y₂O₃-based coatings.
| Category |
Description |
| Melting Point | Lowered to 1,940°C from Y₂O₃’s 2,425°C → enables more complete melting, reduces porosity, and improves adhesion |
| Increased Mechanical Strength | Enhanced via tetrahedral bonded Al-site structure, delivering superior strength over conventional Y₂O₃ |
| Defects (Pores & Cracks) | Reduced by approximately 50% compared to Y₂O₃ |
| Plasma Erosion Resistance | Improved by 35% over Y₂O₃ |
| Hardness | Increased by over 144% compared to Y₂O₃ |
| Volume Resistance | Enhanced to over 10 times greater than Y₂O₃, improving electrical insulation |
Compared to the conventional Y₂O₃, which has a melting point of approximately 2,425°C, UC2™ melts at a lower temperature of around 1,940°C, making it easier to achieve complete melting during the APS (Atmospheric Plasma Spray) process. This enhanced meltability helps to reduce porosity within the coating layer and improve adhesion to the substrate, significantly contributing to overall coating stability.When compared to traditional Y₂O₃ coatings, UC2™ reduces the defect rate (pores and cracks) by more than 50% and improves plasma erosion resistance by over 35%. Its hardness is increased by more than 144%, and its volume resistivity is enhanced over tenfold, resulting in significantly improved electrical insulation performance.
In addition, UC2™ Coating features a specialized aluminum-based tetrahedral structure, which further enhances its mechanical strength. This unique structure allows the coating to maintain long-term stable performance without cracking or delamination, even under repetitive plasma exposure.
UC2™ Coating is particularly applied to high-precision components such as Electrostatic Chucks (ESCs), Focus Rings, and Liners, where it forms a stable protective layer even under high-temperature and high-plasma environments. More recently, its application has been expanding into display manufacturing, advanced materials industries, and energy equipment, where high durability and reliability are essential.
Based on its excellent plasma resistance and structural stability, the YAG-based UC2™ Coating makes a substantial contribution to improving semiconductor process yield and extending equipment lifespan.
In the next article, we will introduce FineCera™ Coating, a technology based on YF₃ (Yttrium Fluoride). FineCera™ is drawing attention as a core solution for suppressing particle generation and significantly enhancing initial process stability, thereby boosting both process reliability and productivity in semiconductor manufacturing.
Please stay tuned for the next feature.
<About KoMiCo>
KoMiCo, established in 1996, was the first company in Korea to commercialize cleaning and coating services for semiconductor equipment components. With global operations spanning the United States, China, Taiwan, and Singapore, KoMiCo has earned quality certifications from some of the world’s leading semiconductor manufacturers, solidifying its position as a Global No.1 in the industry.
Building on its advanced cleaning and coating technologies, KoMiCo continues to enhance its core business while expanding into the development and supply of key OEM components for semiconductor equipment. Moving forward, the company remains committed to improving customers’ productivity and yield, and aims to become a global leader in the semiconductor component cleaning, coating, and manufacturing industry.