Tris(2,3-dimethyl-2-butoxy)gadolinium(III) Gd(OCMe2iPr)3, (Gd(DMB)3) was synthesized and characterized.
Gd(DMB)3 was applied as precursor for ALD growth of Gd2O3 (with H2O as oxygen source co-precursor) [19]. Gd(DMB)3 precursor was evaporated at 195°C/2-3mbar With Gd(OCMe2iPr)3 as Gd source, Gd2O3 films were grown in a temperature range of 250–400 °C, and the layers started to crystallize at substrate temperatures as low as 250 °C. The growth rates were 0.34-0.49 A˚ per cycle.[i]
[i] S. Dueñas, H. Castán, H. García, A. Gómez, L. Bailón, K. Kukli, T. Hatanpää, J. Lu, M. Ritala, M. Leskelä, J. Electrochem. Soc., Vol.154, Iss.10, pp. G207-G214 (2007)], “Electrical Properties of Atomic-Layer-Deposited Thin Gadolinium Oxide High-k Gate Dielectrics”
Tris(2,3-dimethyl-2-butoxy)gadolinium(III) Gd(OCMe2iPr)3, (Gd(DMB)3) was synthesized and characterized. Gd(DMB)3 is volatile (was vaporised in ALD conditions at 195°C/2-3mbar, see below)
Tris(2,3-dimethyl-2-butoxy)gadolinium(III) Gd(DMB)3 was applied as precursor for ALD growth of Gd2O3 (with H2O as oxygen source co-precursor) . Gd(DMB)3 precursor was evaporated at 195°C/2-3mbar. With Gd(OCMe2iPr)3 as Gd source, Gd2O3 films were grown in a temperature range of 250–400 °C, and the layers started to crystallize at substrate temperatures as low as 250 °C. The growth rates were 0.34-0.49 Å/ cycle. Better leakage current-voltage characteristics as well as lower flatband voltage shift were obtained for the as-deposited Gd2O3 films on etched (H-terminated) Si(100), compared to SiO2/Si substrates; Al/Gd2O3/ HF-etched Si samples also exhibited lower interface trap densities (if annealed at rather high temperatures).[i]
In another report, Gd(DMB)3 and H2O vapor were applied for the ALD growth of thin cubic Gd2O3 films at 300–400 °C temperatures; crystalline films were obtained even in the as-deposited state. The layers had some residual H and C impurities and were probably O-deficient in the as-deposited state, causing flat-band shifts in Gd2O3-based metal-oxide-semiconductor (MOS) capacitor structures. The permittivity of 16 (calculated from the relationship between EOT and physical oxide thicknesses) and breakdown fields as high as 8 MV/cm were obtained for the Gd(DMB)3-grown Gd2O3 dielectric layers.[ii]
[i] S. Dueñas, H. Castán, H. García, A. Gómez, L. Bailón, K. Kukli, T. Hatanpää, J. Lu, M. Ritala, M. Leskelä, J. Electrochem. Soc., Vol.154, Iss.10, pp. G207-G214 (2007)], “Electrical Properties of Atomic-Layer-Deposited Thin Gadolinium Oxide High-k Gate Dielectrics”
[ii] K. Kukli, T. Hatanpää, M. Ritala, M. Leskelä, Chem. Vapor Dep., Vol 13, Iss 10, p.546–552, 2007. DOI: 10.1002/cvde.200706631, “ Atomic Layer Deposition of Gadolinium Oxide Films”
[Gd(mmp)3] (mmp = 1-methoxy-2-methyl-2-propanolate, OCMe2CH2OMe) was synthesized by the alcoholysis of gadolinium (III) bis(trimethylsilylamide) in toluene:
Gd[N(SiMe3)2]3 + 3 mmpH (toluene) -> [Gd(mmp)3] + 3 NH(SiMe3)2
[Gd(mmp)3] is volatile and was applied as precursor for the MOCVD and ALD growth of Gd-containing thin films. [[i]]
[i]H.C. Aspinall, J.M. Gaskell, Y.F. Loo, A.C. Jones *, P.R. Chalker, R.J. Potter, L.M. Smith, G.W. Critchlow, Chem. Vapor Dep., 2004, 10, 301-305.
[(Gd(mmp)3] is volatile and was applied as precursor for the deposition of cubic Gd2O3 thin films by liquid injection MOCVD at 300-600°C temperatures on Si(100) and GaAs(100) substrates, [(Gd(mmp)3] precursor was evaporated at >170°C/2-3 mbar. Carbon-free GdOx films were obtained; over a wide range of substrate temperatures (300–600 °C). GdOx films grown on Si(100) were amorphous at low growth temperatures, and crystalline ( C-type structure) at growth temperatures ≥450 °C, according to XRD. Strong preferred orientation ((222) dominated) was observed for the GdOx films grown on GaAs at 450°C.[i]
[i] Y.F. Loo, R.J. Potter, A.C. Jones, H.C. Aspinall, J.M. Gaskell, P.R. Chalker, L.M. Smith, G.W. Critchlow, Chem. Vapor Dep., 2004, Vol.10, Iss.6, p. 306, “Growth Gadolinium Oxide This Films by Liquid Injection MOCVD Using a New Gadolinium Alkoxide Precursor”
[(Gd(mmp)3] was as well applied as precursor for deposition of C-Gd2O3 layers on Si(100) substrates by liquid injection ALD at 150-450°C, using alternate pulses of Gd(mmp)3 and H2O vapor. For comparison, Gd2O3 layers were grown by thermal MOCVD in the same reactor. As-grown Gd2O3 films were partially crystalline, according to XRD. No any C impurities were detected in the Gd2O3 films by AES. Gd2O3 growth using [(Gd(mmp)3] precursor was not fully self-limiting at 225 °C (the self-limiting behaviour was studied by varying the volume of precursor injected during each ALD cycle). A deposition mechanism involving β-hydride elimination of the mmp group was proposed, as well as general mechanistic principles that may influence the ALD growth of Gd2O3 using other precursors.[i]
[i] R.J. Potter, P.R. Chalker, T.D. Manning, H.C. Aspinall, Y.F. Loo, A.C. Jones, L.M. Smith, G.W. Critchlow, M. Schumacher, Chem. Vapor Dep., Vol.11, Iss.3, p.159–169, 2005; DOI: 10.1002/cvde.200406348, “Deposition of HfO2, Gd2O3 and PrOx by Liquid Injection ALD Techniques”
Gadolinium tris(1-methoxy-2-methyl-2-propanolate) tetraglyme adduct [Gd(mmp)3] /3 •tetraglyme was reported to be a volatile compound (vaporises at >170 °C/2−3 mbar in the
liquid injection MOCVD conditions, and was successfully applied as precursor for the MOCVD of Gd2O3 films.[i].
[i] H.C. Aspinall, J.M. Gaskell, Y.F. Loo, A.C. Jones *, P.R. Chalker, R.J. Potter, L.M. Smith, G.W. Critchlow, Chem. Vapor Dep., 2004, 10, 301-305.
[Gd(mmp)3]x tetraglyme was applied for the deposition of Gd2O3 films by MOCVD at temperatures 300-600°C on Si(1 0 0). The crystallinity of the as-deposited films at different temperatures was studied by XRD.(Fig.)
Analogously, GdOx films were grown on GaAs(100) at 400-450 °C temperatures, their crystallinity was investigated by XRD.(Fig.) [i]
[i] A.C.Jones, H.C.Aspinall, P.R. Chalker, R.J. Potter, K. Kukli, A. Rahtu, M. Ritala, M. Leskelä, Materials Science and Engineering: B, 2005, Vol. 118, Iss. 1–3, p. 97–104, EMRS 2004, “Symposium D: Functional Oxides for Advanced Semiconductor Technologies Recent developments in the MOCVD and ALD of rare earth oxides and silicates”