Magnetron Sputtering - Technology and Processes

SPUTTERING

SPUTTERING

Working principle of magnetron sputtering

Magnetron sputtering –
Technology, process & systems

Magnetron sputtering is a physical vapour deposition (PVD) technique in which high-energy ions from a plasma bombard a solid target material, ejecting atoms that travel through a vacuum and condense as a thin film on a substrate.

What sets it apart from basic sputtering is the arrangement of magnets behind the target: these create a magnetic field that traps electrons near the target surface, sustaining a dense, stable plasma at lower operating pressures and voltages. The result is faster deposition rates, better film quality, and reduced substrate heating compared to conventional sputtering, making magnetron sputtering the standard method for depositing metals, alloys, oxides, and nitrides across microelectronics, optical coatings, hard surface treatments, and research applications.

What is sputtering?

Sputtering, also referred to as cathodic sputtering or sputter deposition, is one of the two principal methods for depositing thin metal films, the other being thermal evaporation.

In sputtering, a target of the source material is placed in a vacuum chamber alongside the substrate to be coated. An inert gas (typically argon) is introduced and ionised into a plasma. The positively charged ions are accelerated toward the negatively biased target, striking it with enough energy to eject, or “sputter”, atoms from the surface. These atoms travel across the chamber and deposit on the substrate, forming a thin, adherent film. The number of atoms ejected per incident ion, the sputtering yield, depends on the target material, ion energy, and angle of incidence, and is a key parameter when optimising deposition rate and film uniformity.

Compared to evaporation, sputter deposition offers better step coverage on complex geometries, greater flexibility with compound and alloy targets, and superior adhesion. It is the standard thin film coating technology in microelectronics, optical coatings, hard surface treatments, and decorative applications.

How does magnetron sputtering work?

The defining feature of magnetron sputtering – compared to basic diode sputtering – is the arrangement of magnets behind the target. These magnets create a closed magnetic field above the target surface that traps secondary electrons in a tight orbit. The trapped electrons dramatically increase the rate of ionising collisions with argon gas, sustaining a dense plasma at much lower pressures (typically 0.1–1 Pa) and lower voltages than is possible without the magnetic field.

This high plasma density translates directly into a higher flux of ions striking the target, giving faster deposition rates, better film quality, and reduced substrate heating – key advantages for temperature-sensitive substrates.

Reactive sputtering introduces a reactive gas such as oxygen or nitrogen alongside argon. The reactive gas reacts with the ejected target atoms, forming compound films (e.g. TiO₂, Si₃N₄, AlN) without needing a compound target.

Magnetron sputtering deposition processes

The choice of sputtering process depends on the target material, the required film properties, and production throughput. Polyteknik AS has deep experience across all major magnetron sputtering configurations.

DC sputtering

The simplest and most widely used configuration for conductive sputtering targets. A direct current is applied between target and substrate, making it best suited to elemental metals such as aluminium, titanium, copper, and molybdenum, where the target remains conductive throughout the process.

Bipolar sputtering

Alternates polarity between two adjacent targets, suppressing arcing during reactive deposition. Delivers stable, high-rate deposition of compound films with minimal defects and is well suited to production environments.

RF sputtering

Radio-frequency alternating current prevents charge build-up on non-conductive sputtering targets such as ceramics, glasses, and polymers. RF sputtering enables direct deposition of insulating materials without the need for a metallic target and reactive gas, making it the standard approach for oxide and nitride films in optical and semiconductor applications.

HiPIMS

High-Power Impulse Magnetron Sputtering (HiPIMS) delivers very high peak power in short pulses, generating an exceptionally dense, highly ionised plasma.

The resulting films have superior density, adhesion, and smoothness — critical for hard coatings, diffusion barriers, wide-bandgap semiconductor layers, and precision optical applications. HiPIMS is increasingly specified wherever conventional DC or RF sputtering cannot meet the film quality requirements..

Pulsed DC sputtering

A pulsed power supply periodically reverses the target bias, discharging accumulated charge before arcing can occur. Preferred for reactive sputtering of oxide and nitride films from metallic targets, where conventional DC would lead to unstable arcing.

Polyteknik PVD platforms – magnetron sputtering

The PVD platforms provided by Polyteknik AS, like Flextura and Infinity VB, utilises magnetron sputtering in varying configurations. However, if deposition of several thin film materials is required, co-deposition can be realised in a single Flextura Module, which can be attached to our Flextura Cluster platform for high volume and reliable production.

Polyteknik delivers advanced magnetron sputtering solutions for research & development as well as an integrated part of the industrial production line. From DC and RF sputtering to HiPIMS, our modular platforms are built around the processes that matter to customer applications.

Are you interested in a sputtering module?
Contact our highly experienced team for an attentive and technical discussion regarding your needs or read more about our PVD systems!

Contact us

PVD systems