What Is a PVD Crucible for Vacuum Evaporation?

Vacuum evaporation is one of the earliest methods used in physical vapor deposition (PVD). Common techniques include thermal evaporation, electron beam evaporation, sputtering, and arc evaporation. Among these, thermal evaporation involves heating a source material under high vacuum until it vaporizes. The heating device, known as the evaporation source, holds the coating material inside a crucible. As the crucible is heated, the material either evaporates from its liquid phase or sublimates directly from the solid state, and the resulting vapor condenses on the substrate surface to form a thin film. Heating methods typically include resistive heating and high-frequency induction heating.

Role and Design of Evaporation Crucibles

An evaporation crucible is a key component in thermal evaporation processes. It is used to hold the material during heating and vaporization. These crucibles are typically shaped like bowls or cylinders, though custom shapes are also available. Alumina (Al₂O₃) is commonly used due to its high melting point, thermal stability, and resistance to chemical corrosion, making it suitable for many high-temperature deposition applications.

Evaporation crucibles are essential in processes such as thin film deposition, vacuum deposition, and PVD coating, serving as high-temperature containers that hold the source material and help maintain the purity of the deposited layer.

Crucible Liners: When and Why to Use Them

Evaporation crucibles can be either with or without Crucible liners, depending on the application. A liner is a small container placed inside the crucible to isolate the source material from the crucible wall. It helps prevent reactions, corrosion, or mechanical damage caused by molten material or thermal stress during cooling.

Common liner materials include molybdenum (Mo), tantalum (Ta), tungsten (W), nickel (Ni), and pyrolytic boron nitride (PBN).

For example, an Al₂O₃ crucible with a PBN liner is suitable for aluminum evaporation at temperatures up to 1300°C.

Materials That Can Be Evaporated Directly in Alumina Crucibles

Some materials do not require liners when used with high alumina ceramic crucibles, as they do not become molten or react with the crucible at working temperatures. Examples include:

• Chromium (Cr): Sublimates at around 1650°C, bypassing the liquid phase, which minimizes risk of crucible damage.

• Gold (Au): Can be evaporated directly in a pure alumina crucible at 1550–1600°C.

• Boron (B): Works at high temperatures, but may corrode the crucible above 1600°C, so care is needed.

• Cobalt (Co): Vaporizes at approximately 1640°C and can be used without a liner.

• Iron (Fe): May react with metal liners, making alumina a better option. Recommended temperature: 1550–1600°C.

Germanium (Ge): Sensitive to rapid temperature changes. A controlled heating/cooling rate and stable temperature around 1500°C is advised.

WEIERT CERAMICS – A Leading Manufacturer of High Purity Alumina Ceramic Crucibles in China.

As a company specializing in high alumina ceramic materials, WEIERT CERAMICS has built extensive experience in manufacturing and processing high-performance ceramic crucibles. With advanced production processes and continuously optimized workflows, we are able to efficiently control manufacturing costs while maintaining consistent supply of high purity Al2O3 crucibles. Our products not only meet high-quality standards, but they also significantly improve profitability for our clients.

Our crucibles are widely used in vacuum coating, PVD processes, thin film deposition, and other advanced applications, with several specialized types, including PVD crucibles, evaporation crucibles, vacuum deposition crucibles, and thin film deposition crucibles. All of our products feature excellent high-temperature resistance, making them ideal solutions for high temperature crucible applications.

In addition, we offer customized crucibles tailored to your specific requirements, with precise adjustments in terms of size, structure, and compatibility. Choosing WEIERT CERAMICS means partnering with a reliable, cost-effective solution provider.