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Designing with varying indices of refraction versus thickness in very thin optical films was delt with in earlier papers by interpolating the magnitude of the indices for new thicknesses of that material between indices which have been measured for given thicknesses. This has generally proved successful for most applications but could prove problematic in the case of resonant peaks which shift in wavelength with layer thickness. This paper reports a solution to this problem by interpolating in not only the magnitude of the indices but also with the shifting wavelength. This should make it practical to deal with resonant plasmonic phenomena and quantum dot behavior. The possibilities and limitations of this interpolation approach are discussed.

https://doi.org/10.14332/svc23.proc.0038

Optical monitoring is used to control thin film optical coating deposition since the middle of XX century. Advances in optical metrology and computing power enabled creating fully automated optical monitoring systems. Different types of optical monitoring systems (OMS) exist today including systems using direct and indirect monitoring, transmission and reflection, single wavelength and broadband etc. This talk will discuss advantages and limitations of different optical monitoring systems to demonstrate how OMS characteristics affect its performance. The role different OMS components play in system performance will be discussed. We will show how characteristics of optical monitoring system can be tailored to a specific application. Algorithms and strategies used in optical monitoring will also be discussed. Recent advances in optical monitoring will be reviewed. Examples of advanced filters produced with different optical monitoring systems will be demonstrated.

https://doi.org/10.14332/svc23.proc.0037

Particle as issues or even knock-out criterium for advanced coatings are a challenge we have to face. Effects of particles can result in:

• Shortcuts in electrical contacts
• Pinoles that support corrosion, aging
• Light scattering in optical coatings
• Reduction of production yield
• And many more

The talk addresses the correlations and origin if particles with focus on the process technology. Particles originating from the machine or components will be not considered. The emphasis is on particles originating in the process. Therefore, the generation of particles by means of the process technology in general and especially on the role of arcing and the reduction or even elimination of this effect.

The experiments compare reactive sputtering of SiO₂ and Al₂O₃ with OES- and impedance-based process control leading to low- or even no-defect coatings. The talk addresses the correlations and origin if particles with focus on the process technology. Particles originating from the machine or components will be not considered. The emphasis is on particles originating in the process. Therefore, the generation of particles by means of the process technology in general and especially on the role of arcing and the reduction or even elimination of this effect.

The experiments compare reactive sputtering of SiO₂ and Al₂O₃ with OES- and impedance-based process control leading to low- or even no-defect coatings.

The results are important for manufacturers of coating systems and users in microelectronics, displays, optics and sensors and demanding large-area coatings.

https://doi.org/10.14332/svc23.proc.0031

Reported are results for a Transparent Conductive Oxide (TCO) thin film Electromagnetic Interference (EMI) shield with transmittance at near infrared (NIR) wavelengths for a dual laser rangefinder window. The vacuum evaporated TCO was oxygen deficient indium oxide (IO), i.e., In₂O_3-x without Sn doping. The performance achieved with the single layer IO film, which exceeded requirements, was a Shielding Effectiveness (SE) - ≥ 21.3 dB, a sheet resistance of 17.7 Ohms per square, with a transmittance (include glass substrate losses) of 83.5% at both 1060 nm (1.06 micrometers, μm) and 1540 nm (1.54 micrometers, μm).

https://doi.org/10.14332/svc23.proc.0036

Southwell recently reported designs for very narrow band filters with narrow reflectance, broad absorptance, but no transmittance (NBR); and other filters with narrow band absorptance, broad reflectance, but no transmittance (NBA). The surprising index versus thickness patterns for these filters is very similar to narrow bandpass (NBP) filters and general reflectors. When single thin layers of noble metals, on the order of 10 nm, are inserted into the otherwise dielectric material designs, they have dramatic effects. The metals with the right properties of index of refraction for this work turn out to be the bulk values of tantalum and probably other metals. However, when these films are deposited in very thin layers, the properties are not at all like the bulk values. It is therefore necessary to deposit test samples of the candidate materials in the approximate thickness anticipated to be used in the designs. Final designs can then be approached using realistic values for the indices of refraction. It appears that a new specialty area has been opened in the field of optical thin film design.

https://doi.org/10.14332/svc23.proc.0035

The Vera C. Rubin Observatory Coating plant consists of a Coating Chamber for highly reflective coating deposition, using sputtering process with planar magnetrons. Forecasting of the magnetron target degradation for this type of coating plant has always been a difficult problem, given every coating plant and process are different, and the diagnosis has usually relied on visual inspections and experience. In this paper, we attempt to generate a predictive model for the targets degradation of our Coating plant, using process sensor data and machine learning models like neural networks and similar. This approach allows to also model other difficult tasks, like virtual thickness sensors for areas where they can´t be installed.

https://doi.org/10.14332/svc23.proc.0032

Many of today’s products rely on surface engineering solutions to achieve the required product performance. These examples cover a broad field of applications ranging from food packaging, automotive, residential all the way to energy conversion and storage as well as micro- and consumer electronics. The key of surface engineering is the combination of superior materials properties, commonly in form of thin films, with the properties of a wide variety of substrate materials and form factors. The fundamental understanding of the relation between synthesis, structure and properties is mandatory for the demonstration of the suitability of a materials system. However, also its scaling capabilities have to be demonstrated on the way of proving its feasibility in a product or for the specification of adequate production equipment. The latter has to be addressed typically between technology readiness level (TRL) 3-7 posing a serious challenge for new ideas.

Fraunhofer FEPs mission is, therefore, the support of product ideas between these TRLs. For this purpose, Fraunhofer FEP provides suitable equipment and competences for the reproduction of results at laboratory scale and their replication and transfer to scalable and adapted process components as well as commercially relevant substrates.

During this talk the most relevant equipment and technology platforms for either sheet-to-sheet as well as role-to-roll vacuum coating of glass, metal, polymer or wafer substrates will be shown and correlated to application examples, such as plasma activated barrier coatings for food packaging, novel anodes and current collectors for Lithium ion batteries, contact and diffusion layers for H2 applications, optical coating solutions for holographic displays as well as processing of ultra-thin flexible glass.

https://doi.org/10.14332/svc23.proc.0030

The drive to ever-greater quality, throughput and yield has an impact on many areas of the coating process related to power delivery, power management and power analysis. Here, we take a look at three of the most important areas, namely cathode conditioning, power delivery configuration and choice of AC/sine wave or bipolar pulse dual-magnetron sputtering techniques. Cathode conditioning topics will include: potential pitting and nodule growth problems that occur when failing to condition a cathode appropriately; how power supply performance, power control and arc management are critical for controlling the conditioning process while preventing damage to the target; and how software can be used to provide a smart analysis of cathode performance and enable the development of highly customized cathode conditioning and burn-in procedures. Power configuration will look at how dynamic reverse power (DRP) techniques can be used to deliver higher deposition rates and lower substrate heating and to create opportunities to add more materials to a coating line. Finally, we will consider the benefits of switching from an AC to a bipolar approach – including flexibility, sensitivity to arc management and the opportunity to improve deposition rates by operating at lower frequencies. Methods for reducing the challenges of crazing in bipolar environments will also be introduced.

https://doi.org/10.14332/svc23.proc.0062

Thin-film nonuniformity is a fundamental, systematic error present in optical coating systems which leads to limitations on substrate sizes, reductions in capacity, poorer production yield, and other associated issues. Fundamental system design principles, based on source distribution and substrate mounting/motion profiles, can provide significant control over thin-film uniformity. Such an approach greatly improves the overall deposition performance, enabling deposition systems to provide both uniform and prescribed non-uniform film thickness profiles very accurately.

https://doi.org/10.14332/svc23.proc.0034

The need to maximize coater yields in optical glass and large format coated glass is of paramount importance. Low-e, smartglass and coated optical glass are very high value-added and must be defect-free.

As 30% - 70% of all coating defects are due to unclean first surfaces, improving first surface cleanliness is the assured means to increase coater yield. However, there have been no simple means to measure first surface cleanliness, on-line, real-time, 100%. Glass washer and cleaner vendors do not provide this first surface cleanliness measurement, and conventional camera and laser systems are incapable of performing this feat. In addition, these conventional systems are plagued by false hits and constant alignment problems.

A new generation of Solid-State Laser Reflection (SSLR) scanners has been developed and proven for both optical glass and large format coated glass inspection; 1μm defects and “invisible” residue are easily detected. These in-line 100% automatic glass cleanliness measurement systems deliver a host of benefits including increased yield, scrap reduction, reduced labor cost and maximum customer satisfaction. In addition, SSLR technology is self-aligning, solving the problems associated with all conventional inspection technologies.

System theory will be explained and application examples will be presented.

https://doi.org/10.14332/svc23.proc.0063