Vacuum Coating Technologies

Vacuum coating technologies are a group of technologies, in which the environment for small particles - atoms, molecules, ions and electrons are provided for them to follow thermal motion and electric and magnetic force fields. Whereas in contrast as a group of particles within solid material, liquid or gas they would rather collectively obey the inter-molecular forces, fluid dynamics and laws of gravity. 

A physical vacuum find its mirror in solid matter. Though firm to the touch, a solid—much like a vacuum—is 99.999...% 'void,' an inter-atomic expanse where particles navigate invisible electromagnetic fields. In a solid, vast energy is locked into its atomic structure, amount of nuclear bomb in a single gram. In plasma and vapor particles dance somewhat more freely, allowing to deposit the energy. Vacuum coating technology simply clears the stage and removes ambient molecules so these atoms can travel unhindered to their destination.

The level of vacuum can be defined by considering the distance that particles travel before colliding with the neighboring ones. In the air we breathe, molecules try to move rapidly but collide after travelling only ~65 nm and thus behave collectively, diffusing towards lower concentration described by Brownian motion. In the deep vacuum of outer space, however, particles can travel planetary distances before a single encounter. Vacuum coating operates in the "intermediate" zone between these extremes, managing the dynamics of particle flows into, through, and out of a vacuum chamber.

PVD & CVD: The Art of Energy Conversion

Physical vapor deposition (PVD) of a solid source material onto a substrate surface can be established by evaporating source material thermally from a liquefied surface, or by sputtering it by a heavy particle bombardment, extracted from a plasma. Sputtering ejects atoms with roughly ten times the kinetic energy of thermal evaporation, whereas evaporation allows for high deposition rates.

In a vapor phase atoms move with a speed of hundreds or thousands of m/s, ready to condense onto a cooler surface they arrive at. Many variations of these two main PVD technologies, named thermal evaporation and sputtering are developed. At NextGen Surfaces Finland, we harness these high-energy dynamics through (reactive)magnetron sputtering. This allows also to transform electrically conductive alloys into fully ceramic or dielectric films at near room temperature.

In Chemical Vapor Deposition (CVD), molecules are thermally activated to a state where they exhibit a specific chemical affinity for the substrate and each other (In ALD only for substrate). When we add plasma assistance (PA-CVD), we can trigger these reactions through collisions between vapor molecules and particles. This allows the substrate to remain near room temperature during film growth.

While these processes carry many exotic names, they are all essentially methods of converting energy into a desired form and depositing it to provide a specific service on a specific product. While one might not often need a diamond layer on rubber, the reality is that most of material interaction with the surrounding world happens at the surface. Whether the challenge is wear, corrosion, or conductivity success or failure is decided at the surface.