22.2: Invited Paper: Sputtered Molybdenum‐Oxide for Anti‐Reflection Layers in Displays: Optical Properties and Thermal Stability

Abstract

Molybdenum (Mo) is commonly used for thin film transistor (TFT) metallization in displays. Apart from its outstanding electronic and adhesive properties in the metallic form, it also possesses stable oxidation states, including sub‐stoichiometric oxides. Depending on the amount of oxygen, the properties can be widely tuned and oxygen‐deficient MoO3‐y films can be electrical conducting and optically absorbing, making them suitable candidates for integration as low‐reflection coatings for on/in cell touch, black matrix on array, narrow bezel, or TFT metallization. Deposition of these oxides by fully reactive sputtering from metal targets implies several problems such as lateral inhomogeneities on large substrates (>G5) and difficult control of oxygen flow. To avoid these obstacles, DC‐ sputtering from ceramic Molybdenum oxide targets without the addition of oxygen gas is proposed.In our work, we show the non‐reactive DC‐sputtering of MoOx:TaOx in a stable and reliable process with deposition rates of up to 180 nm/min. Further on, the electrical, optical, and structural properties of the resulting films are studied. The reflectance of light from external sources and the resulting color impression of the dark layer coatings is investigated on different substrates. The color coordinates of the film can be tuned by the layer thickness, the type of covered metal layer (e.g. Cu, Al, Mo), as well as composition of the oxide. From a process stability point of view, we discuss changes during additional annealing steps, and show structural changes at elevated temperatures.

54‐3: A Full‐Color Decorative Display Integrated with Anti‐Reflection Film

“…The clear area of this metal layer can be used for display and the dark area be as decorations. Aluminum or molybdenum metal layer is used as the substrate, and by adjusting the thickness of the Anti-reflection Film [2,3], colorful devices with different colors and low reflectivity can be obtained. Colorful devices with a low reflectivity of 14-16% and a high transmittance of 73%-74% can be obtained by adding an ITO film layer between the metal layer and the anti-reflection film layer and adjusting the film thickness.…”

Thermal Stability, Optical and Electrical Properties of Substoichiometric Molybdenum Oxide

“…Among the applications of molybdenum oxide, substoichiometric molybdenum oxide has gradually received more attention because of its excellent optical, electrical and catalytic properties. In the field of optoelectronics, MoO x can be used in the antireflection layer of displays [ 10 , 11 ], to improve solar energy conversion efficiency [ 12 , 13 , 14 , 15 ] and in new-generation sodium magnesium batteries [ 16 , 17 , 18 ]. In addition, it can also be used in catalysis [ 19 , 20 ], biomedicine [ 21 ], electronic devices [ 22 , 23 ] and other fields.…”

“…It can also be stacked with high work function metals, e.g., Ni, and subjected to certain heat treatments for higher stability [ 29 ]. Hennrik Schmidt et al [ 11 ] found that the original amorphous MoO x films prepared by magnetron sputtering began to transform into crystalline MoO 2 films after thermal treatment at 350 °C. It can be observed that this substoichiometric molybdenum oxide exists stably only within a specific temperature range, and the thermal stability, decomposition mechanism and phase generated in the decomposition process have not been studied in detail.…”

Effects of Sintering Temperature on MoOx Target and Film

“…Pachlhofer et al [11] synthesized Mo-O thin films using ceramic MoO x targets with compositions ranging from x = 2.5 to 2.8. To investigate the reflectance of light from external sources and the resulting color impression of the dark layer coatings, Hennrik [25] used ceramic oxide targets to deposit a thin layer of metal oxide.…”