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High quality compound coatings can be deposited by reactive magnetron sputtering. Optimal stoichiometry and properties of the produced coatings can be achieved by operating in a transition state of the reactive sputtering process. This state is, however, history-dependent and varies with the previous conditions used in the coating equipment. Moreover, the process conditions during the deposition can also drift due to long term effects. A discussed example is the drift of the discharge voltage as a consequence of the deposition of an insulating coating onto the vacuum chamber walls. This example was chosen because it hindered the validation of our computational model for reactive magnetron sputtering. The development of a new probe that compensates for the observed voltage drift not only advances our understanding of the reactive process, but also fixes the chosen transition state for thin film deposition.

https://doi.org/10.14332/svc24.proc.0067

A new three-layer, with three materials, antireflection (AR) coating design has been discovered. The designs for the classic three- and four-layer AR coatings in common use, when optimized with respect to the photopic response of the eye, can reduce the luminous (Y) value of reflectance to between 0.05 and 0.08 or 0.05% to 0.08%, as compared to 4.3% for uncoated crown glass. This invention can further reduce this to 0.02%. The classical three-layer AR design employs successive layers on the glass substrate of: medium, high, and low indices of refraction which are approximately one quarter, one half, and one quarter wavelength of optical thickness at a wavelength near the center of the visible spectrum. This discovery uses a notably different material for the second layer, and thereby reduces the photopic reflectance by a factor of 2 to 4 times. The performance depends a great deal on the detail index of refraction properties of this material.

https://doi.org/10.14332/svc24.proc.0031

The advent of the extensive use of Zoom and similar meeting venues has made the reflection from eyeglasses more apparent and distracting. Eyeglass lenses which have not been antireflection (AR) coated typically reflect more than 4% of light from each lens surface or more than 8% per lens. Lenses with the common 4-layer AR coating still reflect more than 0.5% of greenish or bluish light per surface. When we observe the reflection of a bright computer screen or other illumination sources in someone’s glasses while they are communicating with a video image, it is particularly distracting if they have uncoated lenses, but it still can be distracting even with the common 4-layer AR coatings. The currently available technology will allow the reduction of these reflections by an order of magnitude so that we can “look someone in the eye” when we talk with them via video conferencing. The new coatings would probably use 6-10 layers, which is not many layers as compared to more sophisticated applications where over 100 layers are now used. The common production issues limiting performance now are inadequate reproducibility of factors like pressure, rate, uniformity, temperature, etc. Tighter process control would tend to make these coatings somewhat more expensive than the present 4-layer coatings, but discerning users would probably be willing to pay a premium for their improved appearance when being viewed by video.

https://doi.org/10.14332/svc24.proc.0030

A collection of interesting vacuum-coating challenges will be presented, from uniformly coating small glass spheres to roll-to-roll coating paper, along with the solutions implemented.

https://doi.org/10.14332/svc24.proc.0026

We explored leveraging a Plasma Emission Monitor (PEM) to effectively develop a reactive titanium nitride sputtering process in a production batch-coating PVD system. It is essential for the system to have optical sensors precisely placed to view the plasma, optimally designed gas rings to inject reactive gas into the sputter plasma, and properly located MFCs to adjust reactive gas flow rates promptly. The PEM was set to track the relative intensity of the Ti/Ar emission spectra from the plasma, which decreases as the nitrogen gas ratio increases. The reactive gas flow was controlled by the PEM to maintain an emission intensity setpoint, which was found to correlate to the deposition rate and nitrogen concentration in the TiN films. This allowed us to rapidly develop a process to deposit TiN films with a resistivity < 150 μohm-cm on unheated substrates. Once the process was developed, the PEM allowed for repeatable film deposition of similar quality. Overall, the PEM is a great solution for controlling and developing reactive sputtering processes.

https://doi.org/10.14332/svc24.proc.0036

Masking of glass substrates by printable media is already used in the architectural and automotive glass industries. Within this process, the desired area on the substrate that should be kept without the coating is covered with the masking material by a screen or digital printer, the applied mask is dried or cured by UV light, a PVD coating is applied, and the coated mask is removed either by water or a chemical solvent.
For the implementation of the mentioned steps within the in-line processing of large area glass substrates, several challenges have to be solved. First, printing technology should be suitable for the process cycle time, which in some cases can be below 30 seconds. At the same time, requirements on a high print resolution, a long uptime of equipment, and low operational costs should be fulfilled. Second, the selected masking material should be compatible with magnetron sputtering processes: on one hand, exposed plasma should not damage the mask pattern, and on the hand, the outgassing rate of applied mask should be low to minimize the impact on the sputtering process. Additionally, cost of the applied mask per square meter is a crucial factor driving the choice of the print technology, especially for large area applications. Third, washing off the mask after the sputtering process should not damage the applied film, whereas coated masking material should be completely removed from the glass surface. Residuals of coating and mask material remaining in tanks with used water or solvent must be filtered out to prevent their redeposition on the next substrates entering the washing area.
Successful solution of the mentioned challenges will allow to expand the range of applications for printable masking in a sputtering process. Masking technology can potentially replace the process of edge deletion on the glass, which is nowadays required for production of individual glass units for residential and commercial buildings. It can be effectively used for production of a bird protection glass which requires specific patterns nearly invisible for humans but well recognized by birds. Another field of application is the automotive industry: sunroofs and windshields of modern cars coated with low emission films always require uncoated areas, sometimes with specific pattern, to transmit various signals e.g. rain sensors, traffic sign recognition, etc. The application of printable masks enables an extremely accurate, high yield and cost-efficient high throughput production in the field of automotive products.
In this contribution different process optimization approaches of the large area masking technology are discussed, and first essential validation results of this in-line masking and coating technology are presented.

https://doi.org/10.14332/svc24.proc.0019

Gravitational-wave detectors (GWD) are ultra-sensitive, large-scale facilities whose successful operation depends critically -among various factors- on the performance of high-reflective mirrors. These consist of doublets of high- and low-refractive-index amorphous oxide coatings deposited by ion beam sputtering (IBS). Their performance, defined in terms of high reflectivity, low optical absorption and low thermal noise, can be enhanced by optimizing the constituent materials, the deposition and post-deposition processes such as the thermal annealing. In this contribution, an implementation of real-time spectroscopic ellipsometry is proposed as a convenient tool to understand the evolution of coatings properties during the post-deposition thermal annealing. The amorphous titania-tantala coating and the annealing protocol considered here match those currently used in mirrors for GWD. In-situ analysis shows the evolution of the coating refractive index and thickness throughout the annealing, including the heating and cooling ramps. Results indicate that the current annealing protocol leaves room for further possible modifications in the coatings properties and suggest ways to optimize it. The in-situ analysis discussed here can be beneficial to screen and validate other coating materials as well as to test new annealing protocols to enhance the properties of mirror coatings for GWD applications.

https://doi.org/10.14332/svc24.proc.0029

A proprietary approach to reflection and transmission measurements using the Carl Zeiss ThinProcess UV/Vis/NIR platforms will be discussed. The following topics will be included: conventional design; Zeiss design; instrument to instrument reproducibility; supplier to supplier reproducibility; measuring on-line reflection and transmission with “lab-like” uncertainty.

https://doi.org/10.14332/svc24.proc.0038

Electrochemical capacitors (ECs) are an important component of modern energy storage due to their fast charge-discharge kinetics, high power density, and long operating life. This work investigates the electrochemical behaviour and morphological characteristics of mercury sulfide (HgS) electrodes, using cyclic voltammetry and scanning electron microscopy for a thorough analysis. HgS was produced using a single-step hydrothermal method. X-ray diffraction revealed the presence of single-phase HgS. The W-H and S-S plots determine the crystallite size. UV-Vis spectroscopy investigation indicates absorption in both UV and visible regions, with an optical energy band gap of 0.79 eV. FESEM detected nano-polyhedral particles. EDS analysis using FESEM revealed the presence of mercury and sulfur. The Nyquist plot and cyclic voltammetry showed capacitive behavior, indicating compatibility with batteries and supercapacitors. The study thoroughly investigates HgS electrodes to identify crucial elements influencing capacitance performance, such as electrode shape, surface area, and material composition. The findings highlight HgS's potential as an effective electrode material and provide insights into its use in developing EC technology. This study contributes to the ongoing development of energy storage systems by linking fundamental electrochemical principles with comprehensive morphological characterization, paving the way for long-lasting and efficient capacitive devices.

https://doi.org/10.14332/svc24.proc.0051

Over the past years, increased understanding of arc behaviour during thin film deposition processes has led to improvements in plasma power supply design. This has helped significantly minimize negative effects related to arcing. In this contribution, we demonstrate the effect of different arc handling parameters available at the power supplies that can be used to tailor arcing characteristics during sputtering of insulating films. We show the effect of arc management parameters on arc energies, backed by experimental studies on silicon oxide and aluminium oxide processes performed in an industrial drum coater.
To deposit these insulating materials, different power delivery modes are available to a user such as dual magnetron bipolar mode (BP) and dynamic reverse pulsing mode (DRP). We discuss the differences between these two modes, provide an in-depth statistical study to showcase the effect of pulsing frequency on these modes, and compare them in terms of arc rates and energies.

https://doi.org/10.14332/svc24.proc.0020