What is Electron Beam (E-beam) Evaporation?

A Complete Guide to High-Purity Refractory Metal Deposition 

Electron beam (e-beam) evaporation is a physical vapour deposition (PVD) technique that uses a focused beam of high-energy electrons to vaporise a source material. It is particularly valued for its ability to deposit high melting point materials with excellent purity and precise control, making it a popular choice for demanding research and device fabrication applications. 

How Does Electron Beam Evaporation Work?

In an e-beam evaporation source, a heated filament emits electrons, which are accelerated through a high voltage and steered using magnetic fields onto the surface of the source material. The source material sits in a water-cooled crucible, often called a hearth. The intense, localised energy delivered by the electron beam rapidly heats and vaporises the material, while the water-cooled crucible itself remains cool. The resulting vapour travels in a line-of-sight path to the substrate, where it condenses to form a thin film.

Why Use an Electron Beam Instead of Resistive Heating?

• Much higher achievable temperatures, enabling deposition of refractory metals such as tungsten, tantalum, molybdenum and titanium, as well as many dielectric materials.
• The water-cooled crucible reduces the risk of contamination from the container itself, supporting very high film purity.
• Precise control of beam power allows fine, repeatable control of deposition rate, down to sub-monolayer levels.
• Multi-pocket sources allow several materials to be loaded at once, enabling co-deposition and multilayer stacks without breaking vacuum.

Advantages & Limitations

Advantages

• The widest material range of the common PVD techniques, including high melting point metals and dielectrics.
• High film purity due to the water-cooled, contamination-resistant crucible.
• Precise, repeatable deposition rate control, suitable for ultra-thin and sub-monolayer films.
• Multi-pocket designs enable complex multilayer structures to be built up in a single process run.

Limitations

• Higher capital cost and system complexity than thermal evaporation.
• Generation of x-rays during operation, which requires appropriate shielding.
• The electron beam and associated radiant heat can cause some substrate heating, which may need to be managed for temperature-sensitive samples.
• Like other evaporation methods, it is a line-of-sight process.

Common Applications

• Metallisation of samples for electron microscopy (FIB/SEM) sample preparation.
• Semiconductor device fabrication, including contacts and high melting point metal layers.
• Optical coatings requiring high refractive index or refractory materials.
• MEMS and nanofabrication.
• Multilayer thin film stacks for materials research.

E-Beam vs Thermal Evaporation vs Sputtering

Many research groups combine e-beam evaporation with sputtering in the same system to access the full range of materials and film properties they need.

E-Beam Evaporation Sources from Korvus Technology

Korvus offers its propiertary TAU mini evaporator source that uses an electron beam to heat the crucible. This offers high-accuracy, sub-monolayer deposition of high melting point metals, with material evaporated from rods or crucibles. Its four-pocket design allows multiple materials to be co-deposited without breaking vacuum, making it ideal for multilayer research. For ultra-high vacuum applications, the TAU UHV variant extends this capability to UHV-compatible systems.

Additionally we integrate third party high power e-beam sources for more demanding applications – See HEX customisations.