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22.2: Invited Paper: Sputtered Molybdenum‐Oxide for Anti‐Reflection Layers in Displays: Optical Properties and Thermal Stability
Author(s) -
Schmidt Hennrik,
Koestenbauer Harald,
Koestenbauer Judith,
Linke Christian,
Franzke Enrico,
Winkler Joerg
Publication year - 2018
Publication title -
sid symposium digest of technical papers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.351
H-Index - 44
eISSN - 2168-0159
pISSN - 0097-966X
DOI - 10.1002/sdtp.12688
Subject(s) - sputtering , materials science , molybdenum , oxide , thin film transistor , annealing (glass) , optoelectronics , layer (electronics) , oxide thin film transistor , thin film , reflection (computer programming) , ceramic , thermal stability , composite material , chemical engineering , nanotechnology , metallurgy , programming language , engineering , computer science
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 MoO 3‐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.