Ion-beam sputtering (IBS) for precision coatings

COATING TECHNOLOGY

Ion-beam sputtering (IBS) is used to achieve extremely steep filter edges, excellent blocking properties, or for multiple filters. This coating technology is outstandingly suitable for producing efficient beam splitters or short-pass, long-pass and band-pass filters, for example. Highly reflective coatings produced using the IBS process are able to achieve a blocking level of up to OD 6 and also boast the advantage of high laser-damage thresholds. Furthermore, highly efficient beam splitters can be realized – including variants with a
50 % / 50 % split +/- 1 %.

Coating of optical components by means of ion-beam sputtering

For ion-beam sputtered (IBS) coatings, the substrate is brought into the vicinity of the coating material, the so-called target. A separate ion source activates the target by bombarding it so that atoms are beaten out and become deposited on the substrate in the form of a layer. Ion generation from the target and the substrate are kept completely separate, with the result that the thermal load on the substrates during coating is less than that during conventional vapour deposition.

In order to achieve very dense, even and virtually defect-free layers, coating is performed under cleanroom conditions:

  • cleanroom class DIN EN ISO 14644 class 6
  • independently operated with a separate climate-control and filter system


Whether the products are band-pass filters, notch filters or beam splitters produced by ion-beam sputtering – the quality of the substrate is likewise of great relevance to the quality of the outcome.

State-of-the-art IBS units are used for high-end applications in the optical sphere. There are many benefits from the highly reflective coatings realized by these means:

 

  • scattered light means low losses
  • optical parameters have a high level of thermal and climatic stability
  • high laser-damage thresholds
  • high level of mechanical stability
  • The following examples of coatings can be produced as a result:
  • anti-reflective coatings with residual reflection less than 0.2 % in broad band to less than 0.05 % for individual wavelengths
  • Short-pass, long-pass, band-pass, multi-band or notch filters with extremely steep edges and very good blocking up to OD5
  • Highly efficient beam splitters with split ratio 50/50 ± 1

Benefits of ion-beam sputtering

In ion-beam sputtering coating technology, the coating material (used in the form of targets in the unit) is abraded through bombardment by ion sources. During sputtering, the material contacts the substrate with high energy and becomes deposited at dense intervals. Virtually perfect layers are achieved on level substrates.

In addition to ion-beam sputtering, there are other types of sputtering coating processes. A summary of the most important sputtered coatings follows below:

  • DC sputtering: in DC sputtering, direct current is used to transmit a pulse between the substrate and the coating material. Only electrically conductive substrates can be used.
  • HF sputtering: acceleration of ions and electrons in an alternating field releases the coating material from the target in pulses. The substrate heats up less, but coating rates are also comparatively low.
  • Magnetron sputtering: in magnetron sputtering, an additional magnetic field is arranged behind the cathode plate. The sputtering rate increases due to the higher ionization capacity of the electrons/the increased numbers of noble gas ions.

Ion-beam sputtering is particularly suitable for making very dense, even and defect-free layers.

Special features and spheres of application

The ion-beam sputtering system produces the highest-quality optical thin films with improved productivity and throughput. An ion beam system provides outstanding control of layer thickness and improved process stability. It was developed for the latest optical interference coating applications from band-pass filters to beam splitters. 

 

Beam splitters for automatic quality assurance in production in the spheres of

  • sensor technology
  • metrology

Band-pass filters for different laser wavelengths for

  • biomedicine
  • metrology
  • medical technology
  • video projectors
  • events technology
  • and many more

More about applications