Molecular Layer Deposition of Zircone and ZrO₂/Zircone Alloy Films: Growth and Properties

Abstract

Hybrid organic/inorganic polymer films based on zirconium are grown using molecular layer deposition (MLD) techniques. The zirconium alkoxide films, known as ''zircones'', are grown using sequential exposures of zirconium tert-butoxide (ZTB) and ethylene glycol (EG) as the reactants at temperatures from 105 to 1958C. In-situ quartz crystal microbalance (QCM) and ex-situ X-ray reflectivity (XRR) experiments confirm linear growth versus the number of reaction cycles. The growth rates decrease versus temperature from 1.6 Å per cycle at 1058C to 0.3 Å per cycle at 1958C. The measured density is $2.17 g cm À3 for all the growth temperatures. Transmission electron microscopy (TEM) images reveal very uniform and conformal zircone films. ZrO 2 / zircone alloys are also fabricated by combining ZrO 2 atomic layer deposition (ALD) and zircone MLD at 1458C. The composition of the ZrO 2 /zircone alloy is varied by adjusting the relative number of ZrO 2 ALD and zircone MLD cycles in the reaction sequence. The ZrO 2 /zircone alloys display varying density, refractive index, elastic modulus, and hardness. The refractive index and elastic modulus change progressively from n ¼ 1.63 and E¼ 27 AE 0.6 GPa for pure zircone MLD films, to n ¼ 1.86 and E¼ 97 AE 5 GPa for pure ZrO 2 ALD films, respectively. In capacitor structures, the zircone films display low leakage currents and a dielectric constant of $6.7. The zircone films are also utilized as the dielectric layer in pentacene-based thin film transistors (TFTs), which display a high field effect mobility of 2.11 cm 2 V À1 s À1 operating at À3 V with an on/off current ratio of $10 3 . The zircone and ZrO 2 /zircone alloy films provide a new class of hybrid organic/inorganic polymer films for many functional film applications.

Organic–Inorganic Thin Films from TiCl4 and 4‐Aminophenol Precursors: A Model Case of ALD/MLD Hybrid‐Material Growth?

“…[2] Many of the applications of hybrid materials, both the current applications and the potential new ones, require the material to be in thin-film form. [5][6][7][8][9][10][11][12][13][14] Although the history of ALD goes back to the 1960s [15] and 1970s, [16] and even though MLD was introduced already in the 1990s, [17][18][19][20][21] the two techniques were only re- cently combined to synthesize organic-inorganic hybrids. [3,4] The sequential manner of deposition sition of (Ti-O-C 6 H 4 -N=) n thin films from precursors TiCl 4 and 4-aminophenol (AP) with the essentially ideal growth rate of 10-11 Å per ALD/MLD cycle.…”

Hybrid nanomaterials through molecular and atomic layer deposition: Top down, bottom up, and in-between approaches to new materials

“…Again, a strong dependence on the process temperature and the type of the Related to titanicone is zirconium alkoxide or zircone, which was deposited using zirconium tert-butoxide (ZTB) and EG 54 . Also here, the GPC was temperature …”

“…After this initial publication followed zincone 51,52 , titanicone 53 , zircone 54 , as-well-as several variant precursors and processes for the materials listed here. Some of the properties of these hybrid materials were shown to be tunable and seem promising for a large variety of applications that will be described in greater detail below.…”

Highly Stable Lithium Metal Anode Interface via Molecular Layer Deposition Zircone Coatings for Long Life Next‐Generation Battery Systems

“…This work will provide new insight into the development of nanoscale interfacial coatings for Li metal and demonstrates new techniques for the analysis of protection coatings on aL imetal surface. [8,9] Air stability and processability are also important factors to consider for the design of practical Li metal batteries. [8] In this study,t he thickness of the nanoscale interfacial coatings were tuned by the number of MLD subcycles (10, 25, 50 cycles) and denoted as Li@10ZrEG,L i@25ZrEG,a nd Li@50ZrEG,respectively.The deposition of MLD zircone on Li metal was initially confirmed by time-of-flight mass spectrometry depth profiling (ToF-SIMs), as seen in Figure 1B.I nt he near surface region there is ah igh concentration of organic CH À species from the ethylene glycol organic bridging ligands attached to the zirconium metal center.…”

“…In addition, the concentration of Li À species increases with sputtering time,w hich indicates the presence of an artificial thin film coating on the outer surface.F urthermore,t he chemical ion species images are displayed in Figure 1D and confirms that the bulk Li had been reached by the end of the tested sputtering time.T he sputtering rate of % 0.25 nm s À1 corresponds to azircone coating of approximately 5nmthick, which is in line with the previously reported literature on MLD zircone growth rates in this temperature regime. [8,11] To understand the effects of the number of MLD zircone cycles on the electrochemical performance,s ymmetrical Li k Li and Cu k Li cells were fabricated. [10] Ther eactive nature of Li metal under ambient conditions causes serious safety concerns and can lead to the formation of undesirable interfacial reaction products that can degrade electrochemical performance.Therefore,the fabrication of Li metal anodes with improved air-stability are greatly desired for the scale-up and mass production of Li metal batteries.…”