Introduction to Vacuum Deposition
Vacuum deposition[1] — sometimes known as vacuum evaporation — is an overarching term for the specialised processes used to deposit minuscule layers of a material onto a solid surface. Vacuum deposition processes take place in chambers with very low atmospheric pressures, known as vacuums.
Vacuum deposition can include physical vapour deposition (PVD) and chemical vapour deposition (CVD), depending on the vapour source. PVD involves a physical liquid or solid source; CVD utilises a chemical vapour source.
This process has numerous applications, most commonly forming coatings. Scientists use vacuum deposition in the development of optical, mirror, decorative, interference, and wear-resistant coatings.
The Science Behind Vacuum Deposition
The exact process behind vacuum deposition depends on the vapour source — physical or chemical. Physical vapour deposition is the more common process and utilises the following technique, in basic terms[2]:
- A solid or liquid source material becomes vaporised within a vacuum.
- The condensation of the vapuor phase deposits onto the surface material as atoms or molecules, creating a thin PVD coating that is only a few atoms thick.
During this process, the atoms reach the substrate without colliding with residual gas molecules in the chamber. The condensing particles may come from a range of processes, such as sputtering, thermal evaporation, e-beam evaporation, laser ablation, and more.
This physical vapour deposition process takes place within a vacuum chamber or other vacuum environment for a few reasons. First, the vacuum decreases the density of the atoms within the enclosure, lengthening the mean free path of the atoms.
The vacuum also allows for a high thermal evaporation rate compared to other vaporization techniques. This vacuumed chamber keeps the gaseous contamination to a minimum by reducing the density of undesirable atoms.
Vacuum techniques enhance control over the gas and vapour phase composition, allowing for the creation of very specialised thin films suitable for optical coatings. Technicians can create thin films and layers with precise chemical compositions.
Vacuum Deposition in Nanotechnology
Recent developments in the vacuum deposition process have created exciting potential within the field of nanotechnology. Namely, vacuum deposition is uniquely able to produce uniform thin layers on an atomic scale. Physical vapour deposition (PVD) has shown success in the growth of nanowires and nanobelts.
The basic method of producing nanostructures with PVD involves sublimating the source materials in powder form at incredibly hot temperatures. These techniques often use high-purity oxide in powder form, running cooling water over the enclosure in stages to achieve a temperature gradient.
The relationship between nanotechnology and vacuum deposition goes both ways, as researchers have begun using nanotechnology to aid the vacuum deposition process. For example, developments within physical vapour deposition technology have allowed technicians to use nanoscale effects to create optimised, enhanced coatings on materials like glass [3].
One notable application of vacuum deposition within nanostructures is the use of this thin-layer deposition method to fabricate large-scale nanosponges of Zn and CD metals on Si substrates [4].
Additionally, the combination of nanoparticles within vacuum deposition has allowed for an even more uniform coating that was not previously achievable with traditional physical or chemical vapour deposition methods. Applications of vacuum-deposited nanoparticles span a range of industries, including life sciences, nanomedicine, photonics, sensors, glass coatings, and more.
The Significance of Thin Film Deposition
Vacuum deposition is a method of thin film deposition, which boasts numerous applications in nanotechnology and beyond. In broad terms, thin film deposition is the process of depositing a thin film coating onto substrate materials. These thin films often have different properties than the source material; for example, they are often transparent, scratch-resistant, and durable.
Vacuum deposition is simply thin film deposition that occurs within a vacuum pump enclosure to limit environmental contaminants and increase the mean free path. All types of vacuum deposition, including PVD, CVD, and plasma etching, use thin film processing to control the output of the substrate. However, vacuum deposition does not only produce thin films; it can also generate a thicker coating for certain applications.
Because thin film deposition can procure the adhesion of a source material in an atoms-thick layer, this method is ideal for the development of coatings consisting of nanoparticles. Thin film deposition offers optimal layer thickness control, conformality, and subnanometer-level accuracy for nanoparticles [5].
Specific applications for thin films in nanotechnology include:
- Integrated circuit chips
- Micro-electromechanical systems
- Micro-fabricated mechanisms
- Light-emitting diodes
More mainstream applications, such as optical coatings, thin film batteries, and photovoltaic solar cells, are also notable.
HEX Deposition System: The Future of Vacuum Deposition
The HEX PVD system from Korvus Technology is a modular thin film deposition system that offers a range of functionality and versatile configurations.
This device uses a six-sided aluminium-framed vacuum chamber that supports several modular panels, including:
- Blank panel
- Deposition source panel
- QCM panel
- Viewport panel
- PLD instrument processing control panel
It allows for all major PVD and CVD techniques, including sputtering, thermal evaporation, organic physical vapor deposition, and sample preparation for surface analysis.
The combined benefits of the HEX deposition series make vacuum deposition accessible for physics researchers and developers, offering more control and customisation than comparable systems.
Conclusion
Korvus Technology is a leading developer of thin film deposition systems that use vacuum deposition to produce highly optimised, controlled thin-film coatings. Want to learn more about types of vacuum deposition in nanotechnology, such as CVD or plasma etching? Speak with us today to learn how our HEX device can aid your project.
References
[1] Mattox, Donald M. (2010). Vacuum Deposition (Vacuum Evaporation), Handbook of Physical Vapor Deposition (PVD) Processing (Second Edition), Accessed 29 June 2023.
[2] Mattox, Donald M. (2018). Vacuum Deposition–Vacuum Coating–Physical Vapor Deposition–Chemical Vapor Deposition, The Foundations of Vacuum Coating Technology (Second Edition), Accessed 29 June 2023.
[3] Baer, Donald, Burrows, Paul, & Anter A El-Azab. (2003). Enhancing coating functionality using nanoscience and nanotechnology. Progress in Organic Coatings, 47:3-4, 312-356.
[4] Wang, Qun, Chen, Gang, & Nan Zhou. (2009). The large-scale synthesis and growth mechanism of II-B metal nanosponges through a vacuum vapor deposition route. Nanotechnology, 20:8, DOI: 10.1088/0957-4484/20/8/085602.
[5] Ritala, Mikko & Markku Leskela. (1999). Atomic layer epitaxy – a valuable tool for nanotechnology? Nanotechnology, 10:8, DOI: 10.1088/0957-4484/10/1/005.
