IBS – Ion beam sputtering (deposition)
Up to Ø300 mm in size | Coatings up to 5500 nm
IBS (IBD) – Ion beam sputtering (deposition) technology is one of the most important physical vapour deposition (PVD) methods for producing advanced precision optical coatings. It works by sputtering target material using a collimated and neutralized ion beam. The main distinction from other sputtering technologies is that the plasma is generated in a separate chamber, and ions are extracted using a sophisticated grid system. Argon (or xenon) is typically used as the working gas for plasma generation. Accelerated and neutralized ions hit the material target, usually at an angle greater than 50° to the normal, as this allows for a higher sputter yield. The atoms and molecules knocked from the target have very high kinetic energies (~1<Ek<~10 eV), resulting in the formation of compact and dense films.
The main process parameters that can be adjusted and optimized include system geometry, ion energy, ion flux, and background oxygen pressure. Because IBS (IBD) delivers much higher energies to the condensing particles and offers more precise control over process parameters compared to electron beam evaporation, ion beam sputtering is considered a highly stable technology.
- Advantages
- Flatness and stress
- Load Management
- Examples
- Compact and dense layers that are environmentally stable and do not experience spectral shifts due to changes in humidity or temperature
- Amorphous layer structure, resulting in smooth interfaces, very low surface roughness, and correspondingly low coating scatter (typically limited by the initial substrate roughness)
- Possible deposition on unheated substrates, allowing coating of temperature sensitive materials
- Reliable and repeatable batch-to-batch deposition of complex multilayer coatings with precisely controlled spectral and dispersion properties, such as chirped mirrors, interference filters, cut-off filters, etc.
- High LIDT
- Low coating defect density
Ion beam sputtering (ion beam deposition) coatings also have disadvantages, such as high tension or stress, which can lead to a deterioration in the flatness of the final optical component. However, there are several techniques that allow 3photon coating engineers to relieve stress:
- Depositing SiO2 or another material coating layer on the rear surface of the substrate (wafer), which can also serve as an anti-reflective coating. The stress caused by the optical coating on the front surface of the substrate (wafer) can be compensated by the stress of similar amplitude induced by a coating applied to the rear side of the substrate (wafer)
- Applying special thermal procedures to suppress tension within the as-deposited coatings. This technique allows the rear substrate (wafer) surface to remain blank (clear) and helps 3photon coating engineers preserve the initial flatness of the uncoated (bare) substrate in many cases
Load-lock chamber allows to coat several batches non-stop, while keeping the same coating parameters, thus greatly improves the lead-time, reduces cost per unit and ensures repeatability.
Up to two large palettes can be fitted inside the chamber:
e.g. ~100 units of Ø1“(25.4 mm) high reflectivity laser-line mirrors that operate at 1064 nm, 45 degrees of incidence.
With custom holding system we are able to coat about 160 pieces of Ø1“(25.4 mm) substrates in single run.
Option to coat substrates with different dimensions together
Output couplers. PR(R=95% ± 0.5%) @ 1064 nm, AOI=0°, or PR(R=25% ± 0.5%) @ 1064 nm, AOI=0°
Broadband mirrors. HR(Ravg>99%) @ 400-750 nm, AOI=0-45°
Laser line mirrors HR(Rs&p>99.95%) @ 1064 nm, AOI=45°
Low GDD mirrors. Ti:Sapphire mirror with low GDD of ±50 fs and HR(Rs > 99.8%) @ 705-895 nm, AOI=45°
Thin film polarizers HR(Rs > 99.9%) + HT(Tp > 99.96%) @ 1064 nm, AOI=Brewster’s. Extinction ratio >1000:1