ALD of YF3 Thin Films from TiF4 and Y(thd)(3) Precursors

作者：Pilvi Tero^*; Puukilainen Eso; Munnik Frans; Leskela Markku; Ritala Mikko

来源：Chemical Vapor Deposition, 2009, 15(1-3): 27-32.

DOI：10.1002/cvde.200806721

• ALD
• Optical materials
• Thin films
• YF3

Yttrium fluoride (YF3) is a dielectric material with good light transmittance between the ultraviolet (UV) and infrared (IR) range of wavelengths. In this paper we introduce the first use of the atomic layer deposition (ALD) of YF3 thin films. The films are grown at 175-325 degrees C. Y(thd)(3) (thd = 2,2,6,6-tetramethyl-3,5-heptanedionato) is used as a cation source and TiF4 as a fluorine precursor. YF3 film growth characteristics, together with structural, optical, and electrical properties, are studied. Various methods, such as spectrophotornetry, X-ray diffractometry (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and elastic recoil detection analysis (ERDA) are applied to characterize the films. Electrical properties are analyzed from Al/YF3/indium-tin-oxide capacitor structures at room temperature. The growth rates of the films are between 1.1 and 1.7 angstrom per cycle. The films grown below 225 degrees C are amorphous, otherwise they are polycrystalline. The impurities detected in the YF3 film are H, C, O, and Ti. The amount of all of these tends to decrease with increasing deposition temperature, and is only 3.0 at.-% at 325 degrees C. Permittivities of the films are around 6. The refractive indices are 1.51-1.59 (at lambda = 580 nm), and high light transmittance is achieved from the UV to IR regions with the sample grown at 300 degrees C.

• 出版日期2009-3