Anjana Devi

Synthesis, characterization, and thermal properties of homoleptic rare-earth guanidinates: promising precursors for MOCVD and ALD of rare-earth oxide thin films.

Eight novel homoleptic tris-guanidinato complexes M[(N(i)Pr)(2)CNR(2)](3) [M = Y (a), Gd (b), Dy (c) and R = Me (1), Et (2), (i)Pr (3)] have been synthesized and characterized by NMR, CHN-analysis, mass spectrometry and infrared spectroscopy. Single crystal structure analysis revealed that all the compounds are monomers with the rare-earth metal center coordinated to six nitrogen atoms of the three chelating guanidinato ligands in a distorted trigonal prism geometry. With the use of TGA/DTA and isothermal TGA analysis, the thermal characteristics of all the complexes were studied in detail to evaluate their suitability as precursors for thin film deposition by MOCVD and ALD. The (i)Pr-Me(2)N-guanidinates of Y, Gd and Dy (1a-c) showed excellent thermal characteristics in terms of thermal stability and volatility. Additionally, the thermal stability of the (i)Pr-Me(2)N-guanidinates of Y and Dy (1a, c) in solution was investigated by carrying out NMR decomposition experiments and both the compounds were found to be remarkably stable. All these studies indicate that (i)Pr-Me(2)N-guanidinates of Y, Gd and Dy (1a-c) have the prerequisites for MOCVD and ALD applications which were confirmed by the successful deposition of Gd(2)O(3) and Dy(2)O(3) thin films on Si(100) substrates. The MOCVD grown films of Gd(2)O(3) and Dy(2)O(3) were highly oriented in the cubic phase, while the ALD grown films were amorphous.

Hafnium oxide thin film grown by ALD: An XPS study

Hafnium(IV) oxide thin films were synthesized by atomic layer deposition (ALD) on Si(100) substrates, using an innovative guanidinate-stabilized hafnium amide precursor, [Hf(NEtMe)2(EtMeNC(NiPr)2)2]. In the present work, our attention is focused on a detailed XPS characterization of a representative HfO2 coating grown at 350 °C. Beside the wide scan spectrum, detailed spectra for the O 1s, Hf 4f, Hf 4d and C 1s regions and related data are presented and discussed. The obtained results point out to the formation of HfO2 coatings characterized by the presence of -OH groups, whose main origin is attributed to the use of water as oxidizing agent during the preparation process.

A novel Cu(II) chemical vapor deposition precursor: Synthesis, characterization, and chemical vapor deposition

A nonfluorinated beta-diketonate precursor, bis(t- butylacetoacetato)Cu(II) or Cu(tbaoac)2, was synthesized by modifying bis(dipivaloylmethanato)Cu(II) or Cu(dpm)2 for chemical vapor deposition (CVD) of copper. The complex was characterized by a variety of techniques, such as melting point determination, mass spectrometry, infrared spectroscopy, elemental analysis, thermogravimetric and differential thermal analysis, and x-ray diffraction. Cu(tbaoac)(2) has a higher sublimation rate than Cu(dpm)(2) over the temperature range 90- 150 degrees C. Pyrolysis of Cu(tbaoac)2 leads to the formation of copper films at 225 degrees C, compared to 330 degrees C for Cu(dpm)2. As-deposited copper films were highly dense, mirror-bright, adhered strongly to SiO2, and showed a resistivity of less than 2.9 muOmega-cm at a thickness as low as 1300 A. A possible mechanism for the decomposition of the ligand tbaoac has been proposed.

Mixed amide–malonate compound of hafnium as a novel monomeric precursor for MOCVD of HfO2 thin films

The concept of introducing malonates as chelating ligands in combination with metal amides has yielded a new class of compounds which enable growth of HfO2 thin films at low deposition temperatures by liquid injection metalorganic chemical vapour deposition.

Metalorganic chemical vapor deposition of Cu films from bis(t-butyl-3-oxo-butanoato)copper(II): thermodynamic investigation and experimental verification

For the metalorganic chemical vapor deposition (MOCVD) of copper films using the β-diketonate complex copper t-butylacetoacetate or bis(t-butyl-3-oxo-butanoato)copper(II) as the precursor material, the equilibrium concentrations of various condensed and gaseous phases have been thermodynamically calculated, using the criterion of minimization of total Gibbs free energy of the system. The study predicts the deposition of films of metallic copper without the presence of any oxides, even in an inert atmosphere of argon. The Cu films so formed would contain a small amount of carbon, which reduces to zero at higher temperatures. In the reactive ambient of hydrogen, carbon-free copper film is predicted over a wide range of substrate temperatures and total reactor pressures. The thermodynamic yield shows reasonable agreement with experimental observations, though the removal of carbon from the MOCVD-grown copper films in hydrogen is not as complete as the thermodynamic calculations predict.

Nanostructured Dy2O3 films: An XPS Investigation

The present investigation is devoted to the X-ray photoelectron spectroscopy (XPS) analysis of the main core levels (C 1s, O 1s, Dy 4d, Dy 3d) of a representative dysprosium(III) oxide thin film. The specimen was grown on Si(100) at 500 °C by metal organic chemical vapor deposition (MOCVD) starting from Dy((iPrN)2CNMe2)3 in an N2/O2 atmosphere. The above route yielded uniform and homogeneous nanostructured Dy2O3 films characterized by a remarkable reactivity towards atmospheric CO2 and H2O, resulting in the surface co-presence of dysprosium carbonates/bicarbonates and hydroxides. The most relevant spectral features are presented and discussed.

Low-temperature structure of two copper-based precursors for MOCVD: aquabis(tert-butyl acetoacetato)copper(II) and bis(dipivaloylmethanido)copper(II)

The Cu atoms in aquabis(tert-butyl acetoacetato)copper(II),[Cu(C8H13O3)(2)(H2O)], and bis(dipivaloylmethanido)copper(II), [Cu(C11H19O2)(2)], adopt square-pyramidal and planar conformations, respectively, with average Cu--O distances of 1.933 Angstrom in the former (not including the water ligand) and 1.892 Angstrom in the latter. It is interesting to note that the lability of the tert-butyl and methyl groups in both structures, which renders even the location of the terminal C atoms difficult, is reduced at T = 130 K, enabling location of all the protons in the difference Fourier map.

Gd2O3 Nanostructured Thin Films Analyzed by XPS

The present work was devoted to the X-ray photoelectron spectroscopy (XPS) investigation of the principal core levels of a nanostructured Gd2O3 thin film. The sample was synthesized by metal organic chemical vapor deposition (MOCVD) from Gd((iPrN)2CNMe2)3 as precursor at 500 °C in an N2/O2 atmosphere. XPS results evidenced a marked Gd2O3 reactivity towards atmospheric CO2 and H2O, leading to a surface composition characterized by the co-presence of gadolinium carbonates/bicarbonates and hydroxides.

Thermal chemical vapour deposition of copper films from copper ethylacetoacetate : microstructure and electrical resistivity

Thin copper films were deposited through the hydrogen reduction of a non-fluorinated precursor

Thermodynamic investigation of the MOCVD of copper films from bis(2,2,6,6-tetramethyl-3,5-heptadionato)copper(II)

Cu(etaoac)_2