An essential stage in the creation of micro/nanodevices is thin-film deposition. A thin film typically has a thickness of less than 1000 nanometers. Emitting particles from a source (such as heat, high voltage, etc.) initiates the deposition process. The particles are then moved across to the substrate. The particles eventually condense on the substrate’s surface. Chemical and physical vapour deposition are the two main deposition techniques employed today.
E-beam evaporation, also known as electron beam evaporation, is a physical vapour deposition (PVD) procedure that coats a substrate with a thin, dense covering. The coating material (the source material) is evaporated during the process using a high-power electron beam under extreme vacuum conditions. You can refer to this article by Korvus Technology for a more detailed explanation.
Electron beam evaporation has many different commercial uses. It offers customers a practical method for altering the characteristics and functionality of polymers and other materials. Sterilisation of medical equipment, medications, and cosmetics is another common use for the technology.
Electron Beam Evaporation
Physical vapour deposition (PVD) processes that use thermal evaporation include e-beam (electron beam) evaporation and sputtering. E-beam evaporation enables the direct transfer of more energy into the source material, allowing metals and dielectrics with extremely high melting points, such as silicon dioxide and gold, to be evaporated. As a result, materials that cannot be evaporated using conventional resistive thermal evaporation can be deposited. E-beam evaporation provides higher deposition rates than either resistive evaporation or sputtering can offer.
In e-beam evaporation, manufacturers can place the evaporation material into a crucible or a water-cooled copper hearth, which is then heated by a focused electron beam. The electron beam heats the substance, vaporising it before it deposits on the substrate to form the required thin coating.
Compared to other PVD processes, E-Beam Evaporation also has a very high material use efficiency, lowering costs. There is less crucible contamination since the E-Beam technology only warms the intended source material and not the entire crucible. It helps lessen the likelihood of heat damage to the substrate by focusing the energy on the target rather than the whole vacuum chamber.
E-beam vs Sputtering Evaporation
Another physical deposition procedure is sputtering, also known as sputter deposition. Sputtering does not use evaporation, in contrast to thermal and e-beam evaporation. Instead, it fires energised plasma atoms at a negatively charged source material (usually argon because it is inert). A thin film is created when negatively charged source material atoms break off and stick to the substrate due to the impact of positively energised particles. In a vacuum, sputtering is also carried out.
Sputtering, especially for dielectrics, has a lower deposition rate and is carried out at a lower temperature than e-beam evaporation. However, sputtering can produce high-quality thin films and superior coating coverage for more complicated substrates.
How Does E-beam Evaporation Work?
In its most basic form, the e-beam evaporation procedure begins with exposing a source material to an electron beam. The source material is melted and evaporated by the electron beam’s extreme heat. A thin, high-purity coating is produced when the evaporated particles move upward toward the substrate above the source material in the vacuum chamber. When we talk about being thin, we mean being anything from 5 to 250 nanometers thick. Therefore, the coating can alter the substrate’s characteristics without affecting its dimensional accuracy.
More specifically, e-beam evaporation consists of the following essential elements:
● A Vacuum Chamber
● An Electron Beam Source
● A Crucible to hold the material
The electron beam source is a filament consisting of a metal like tungsten heated to temperatures above 2,000 degrees Celsius. The intense heat drives the tungsten filament’s electrons away from the wire, creating kinetic energy. These electrons are focused into a beam and directed at the crucible by a magnetic field created by magnets close to the e-beam source.
The crucible can be built of technical ceramics for coating materials that require higher temperatures or metals like copper or tungsten for coating compounds that don’t need extremely high temperatures. We should be aware that although the e-beam is pointed at the crucible, it primarily interacts with the high-purity source material. The crucible is also continually cooled with water during the operation to avoid melting and mixing with the source material, which would compromise the purity of the product.
The source material’s evaporated particles climb to the top of the vacuum chamber and adhere to the substrate. The device starts a cool down and then a venting sequence to release the vacuum pressure as soon as the necessary thickness has been achieved, which is tracked in real-time by a quartz crystal monitor.
Multiple crucible designs are common in e-beam evaporation systems, enabling the sequential coating of various materials on surfaces. As manufacturers rotate the crucibles, the e-beam evaporates various source materials. They can create multiple coating layers without emptying the machine between each film application. Moreover, they can adjust the e-beam source’s strength to accommodate different coating materials, which melt and evaporate at distinct heat intensities.
E-beam Evaporation Applications
Aerospace, automotive, energy, construction, maritime, manufacturing, electronics, and consumer products are just a few industries that use e-beam evaporation. E-beam evaporation is a very flexible method that allows manufacturers to alter component qualities and customise products to match specific specifications thanks to the wide range of materials that it is compatible with. It’s used specifically when strong temperature resistance, wear, chemical resistance, or optical characteristics are necessary.
The physical vapour deposition approach can be employed for various purposes when using multiple source materials to impart distinct properties. For instance, aerospace businesses can utilise e-beam evaporation to coat specific parts with a dense, temperature-resistant coating, improving the original part’s longevity and capacity to tolerate high temperatures. Optical films for semiconductors and solar cells can also undergo application through e-beam evaporation. Tools and objects used in harsh conditions or demanding applications can receive durable, corrosion-resistant coatings in other sectors.
Takeaways
Physical vapour deposition (PVD) processes like e-beam evaporation use an electron beam to evaporate a source material and deposit thin coatings on a substrate. Moreover, E-beam evaporation is the best method for depositing thin films of high-temperature metals and metal oxides, including silicon dioxide, gold, chromium, and platinum. Thus, e-beam evaporation is employed in many industries to create chemically and temperature-resistant parts and optical components.
