Synthesis of Calcium(II) Amidinate Precursors for Atomic Layer Deposition through a Redox Reaction between Calcium and Amidines

Kim, Sang Bok; Yang, Chuanxi; Powers, Tamara M.; Davis, Luke M.; Lou, Xiabing; Gordon, Roy G.

doi:10.1002/anie.201602406

Cited by 28 publications

(19 citation statements)

References 44 publications

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“…Every atom of the molecule is disordered over four positions. Nonetheless, the structure is generally unremarkable, with an average InÀNdistance, 2.252 (13) ,which is not significantly different from the 2.254(3)-2.271(3) found in two In III guanidinates or the 2.233(5)-2.238(6) found in 2. [8h, 14b] To compare the thermal stabilitya nd volatility of 1 with those of 2 and commercially availableI n(acac) 3 ,t hermogravimetric analysis( TGA) experiments were performed for all three compounds.…”

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confidence: 81%

“…Herein,w er eport an ew In III precursor,t ris(N,N'-diisopropylformamidinato)indium(III) (1,S cheme 1), and as tudy of its reactivity for ALD of In 2 O 3 .W eh ave selected this particulara midinate ligand in light of the excellent volatility and reactivity of its Ca II complex. [13] Compound 1 enables ALD of In 2 O 3 films in the temperature range 150-275 8C, using water as the oxygen source,a taconstant growth rate of 0.55 /cycle. All films depositedi nt he ALD window show resistivity (1-4 10 À3 W·cm) and visible-light transmittance( !…”

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confidence: 99%

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Obtaining a Low and Wide Atomic Layer Deposition Window (150–275 °C) for In₂O₃ Films Using an In^III Amidinate and H₂O

Kim

Jayaraman

Chua

et al. 2018

Chemistry A European J

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Indium oxide is a major component of many technologically important thin films, most notably the transparent conductor indium tin oxide (ITO). Despite being pyrophoric, homoleptic indium(III) alkyls do not allow atomic layer deposition (ALD) of In O using water as a co-precursor at substrate temperatures below 200 °C. Several alternative indium sources have been developed, but none allows ALD at lower temperatures except in the presence of oxidants such as O or O , which are not compatible with some substrates or alloying processes. We have synthesized a new indium precursor, tris(N,N'-diisopropylformamidinato)indium(III), compound 1, which allows ALD of pure, carbon-free In O films using H O as the only co-reactant, on substrates in the temperature range 150-275 °C. In contrast, replacing just the H of the anionic iPrNC(H)NiPr ligand with a methyl group (affording the known tris(N,N'-diisopropylacetamidinato)indium(III), compound 2) results in a considerably higher and narrower ALD window in the analogous reaction with H O (225-300 °C). Kinetic studies demonstrate that a higher rate of surface reactions in both parts of the ALD cycle gives rise to this difference in the ALD windows.

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confidence: 99%

Obtaining a Low and Wide Atomic Layer Deposition Window (150–275 °C) for In₂O₃ Films Using an In^III Amidinate and H₂O

Kim

Jayaraman

Chua

et al. 2018

Chemistry A European J

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“…But meanwhile, the growth rate of NiS was found fairly low (∼0.015 nm/cycle), which implies that the surface reactions perhaps deviated from the conventional ligand-exchange scheme (Scheme a) and therefore deserve particular investigation. On the other hand, the amidinate-type metal precursors recently became increasingly popular in the ALD process development for sulfides, ,− ,,,− and H 2 S has long been the most common accompanying sulfur source; therefore, investigating the surface chemistry for the precursor combination of Ni(amd) 2 and H 2 S is of good representativeness and should be of valuable reference to many other sulfide ALD processes.…”

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Surface Chemistry during Atomic-Layer Deposition of Nickel Sulfide from Nickel Amidinate and H₂S

2018

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Atomic-layer deposition (ALD) of metal-sulfide thin films has recently been developing very fast, and many new metalsulfide ALD processes have emerged during the past several years. Surface chemistry plays a key role in ALD, but it remains yet to be investigated for many recently developed sulfide ALD processes. We herein report our study on the surface chemistry of the ALD of nickel sulfide from bis(N,N′-di-tert-butylacetamidinato)nickel(II) and H 2 S, using the in situ characterization techniques of X-ray photoelectron spectroscopy, low-energy ion scattering, quartz crystal microbalance, and quadrupole mass spectrometry. The surface chemistry is found to deviate from the conventional ligandexchange ALD scheme, and a formation of a nonvolatile acid−base complex from acidic surface sulfhydryl and basic amidine is suggested during the H 2 S half-cycle. Since the precursors used herein are fairly representative, the findings should be of valuable reference for many other metal-sulfide ALD processes.

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“…Crosssectional transmission electron microscopy (TEM) determined the relationship of this heteroepitaxy to be (111) × ALD of Mg x Ca 1−x O was carried out in a home-built tubular reactor. 12 Bis(N,N′-diisopropylacetamidinato)calcium(II) dimer, 13 bis(N,N′-di-sec-butylacetamidinato)magnesium, 14 and H 2 O were used as calcium, magnesium, and oxygen sources, respectively. Structural formulas for the Mg and Ca precursors are shown in Figure 1.…”

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Epitaxial Growth of Mg_xCa_1–xO on GaN by Atomic Layer Deposition

et al. 2016

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Abstract:We demonstrate for the first time that a single-crystalline epitaxial Si-based power devices could not meet these demands due to the small band gap (1.1 eV) and low breakdown field of Si. 2 GaN could replace Si for future power applications because of its higher band gap (3.4eV) and higher breakdown field. One powerful method to examine the epitaxial film quality is cross-sectional TEM imaging. GaN. The well-defined film spots in the diffraction pattern (Fig. S2) peaks are seen in all three samples (Fig. 3 a). The absence of MgO and CaO peaks indicates that phase separation into the two binaries has not occurred. The A "top-to-top" capacitor structure was used to measure the capacitance due to the insulating sapphire substrate under the GaN (Fig. S3). In this measurement, the positive probe is placed in contact with the gate electrode while the negative probe is in contact with the large area of GaN covered by aluminum metal. Since the gate has a serial connection with the large area, the measured capacitance is given by, where m C is the capacitance measured by the LCR meter, g C is the capacitance of the gate and l C is the capacitance of the larger area. Since C l >> C g , the measured capacitance is dominated by the gate: m g C C .The measured room temperature and high temperature CV curves from three Mg x Ca 1-x O /GaN samples as well as an Al 2 O 3 /GaN sample are summarized in Fig. 4.In room temperature studies (Fig. 4 a, b and c there is a 20% dispersion in the same region in the Al 2 O 3 /GaN sample (Fig. 4 d) 20 The detailed measurement procedure and conductance data are summarized in the supporting information (Fig. S5). 18 The measured values of D it are summarized in Fig. 4 i. Two of the samples with epitaxial films show the lowest D it

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Synthesis of Calcium(II) Amidinate Precursors for Atomic Layer Deposition through a Redox Reaction between Calcium and Amidines

Cited by 28 publications

References 44 publications

Obtaining a Low and Wide Atomic Layer Deposition Window (150–275 °C) for In₂O₃ Films Using an In^III Amidinate and H₂O

Obtaining a Low and Wide Atomic Layer Deposition Window (150–275 °C) for In₂O₃ Films Using an In^III Amidinate and H₂O

Surface Chemistry during Atomic-Layer Deposition of Nickel Sulfide from Nickel Amidinate and H₂S

Epitaxial Growth of Mg_xCa_1–xO on GaN by Atomic Layer Deposition

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Synthesis of Calcium(II) Amidinate Precursors for Atomic Layer Deposition through a Redox Reaction between Calcium and Amidines

Cited by 28 publications

References 44 publications

Obtaining a Low and Wide Atomic Layer Deposition Window (150–275 °C) for In2O3 Films Using an InIII Amidinate and H2O

Obtaining a Low and Wide Atomic Layer Deposition Window (150–275 °C) for In2O3 Films Using an InIII Amidinate and H2O

Surface Chemistry during Atomic-Layer Deposition of Nickel Sulfide from Nickel Amidinate and H2S

Epitaxial Growth of MgxCa1–xO on GaN by Atomic Layer Deposition

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Obtaining a Low and Wide Atomic Layer Deposition Window (150–275 °C) for In₂O₃ Films Using an In^III Amidinate and H₂O

Obtaining a Low and Wide Atomic Layer Deposition Window (150–275 °C) for In₂O₃ Films Using an In^III Amidinate and H₂O

Surface Chemistry during Atomic-Layer Deposition of Nickel Sulfide from Nickel Amidinate and H₂S

Epitaxial Growth of Mg_xCa_1–xO on GaN by Atomic Layer Deposition