Abstract
The thermal atomic layer deposition (ThALD) of yttrium oxide (Y2O3) was developed using the newly designed, liquid precursor, Y(EtCp)2(iPr2-amd), as the yttrium source in combination with different oxygen sources, such as ozone, water and even molecular oxygen. Saturation was observed for the growth of the Y2O3 films within an ALD window of 300 to 450 °C and a growth per cycle (GPC) up to 1.1 Å. The resulting Y2O3 films possess a smooth and crystalline structure, while avoiding any carbon and nitrogen contamination, as observed by X-ray photoelectron spectroscopy (XPS). The films showed strong resistance to fluorine-containing plasma, outperforming other resistant materials, such as silicon oxide, silicon nitride and alumina. Interestingly, the hydrophilic character exhibited by the film could be switched to hydrophobic after exposure to air, with water contact angles exceeding 90°. After annealing under N2 flow at 600 °C for 4 min, the hydrophobicity was lost, but proved recoverable after prolonged air exposure or intentional hydrocarbon exposure. The origin of these changes in hydrophobicity was examined.
Highlights
Yttria offers properties that are attractive for a variety of industrial applications
Y2 O3 thin films have been employed as optical, anticorrosive coatings and dielectric insulators in electroluminescent devices, such as light-emitting diodes (LEDs), in which metals such as Eu, Er, Tb and Yb have already been applied as dopants [6]
Yttrium cyclopentadienyl compounds are solid at room temperature and have moderate vapor pressures; they do display high growth per cycle (GPC), typically exceeding well beyond 1 Å/cycle
Summary
Yttria offers properties that are attractive for a variety of industrial applications. Thin films of yttrium-based oxides, in combination with zirconium oxide, are useful as high-k gate dielectrics due to the large intrinsic band gap in the range of 5.5 to 5.8 eV, which displays improved electrical properties on current commercial examples (e.g., lower leakage current) [5]. Interesting properties of yttria are its good wear resistance, high mechanical and dielectric strength, as well as strong corrosion and chemical resistance, making it ideal for wear-resistant coatings in plasma equipment [9]. For such applications, silicon oxide and aluminum oxide are commonly used to shield ceramic components in etchers and plasma-enhanced chemical vapor deposition (PECVD), equipment used in semiconductor processing [10,11]
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