Atomic Hydrogen Induced Chemical Vapor Deposition of Silicon Oxycarbide Thin Films Derived from Diethoxymethylsilane Precursor

Amorphous silicon oxycarbide (a-SiOC:H) films produced by remote plasma RPCVD from diethoxymethylsilane (DEMS) were characterized in terms of their basic properties related to the coatings deposited using conventional plasma enhanced PECVD method. The effect of substrate temperature (T_S) on the growth rate, chemical composition, structure, and properties of resulting a-SiOC:H films is reported. Film growth is an adsorption-controlled process, wherein two mechanisms can be distinguished with a transition at about T_S=70°C. Depending on the temperature, films of different nature can be obtained, from polymer-like to highly crosslinked material with C-Si-O network. The chemical structure of a-SiOC:H films was characterized by FTIR, ¹³C and ²⁹Si solid-state NMR, and X-ray photoelectron spectroscopes. The a-SiOC:H films were also characterized in terms of their density, refractive index, surface morphology, conformality of coverage, hardness, adhesion to a substrate, and friction coefficient. The films were found to be morphologically homogeneous materials exhibiting good conformality of coverage and small surface roughness. Their refractive index exhibits anomalous effect revealing a minimum value at T_S=125°C. Due to their exceptional physical properties a-SiOC:H films produced by RPCVD from DEMS precursor seems to be useful as potential dielectric materials or coatings for various encapsulation applications.     

Mononuclear Imido Amido Complexes via Exhaustive Ammonolysis of Niobium and Tantalum Pentachloride with tert‐Butyl Amine

Reaction of MCl₅ (M = Nb, Ta) with excess of ^tBuNH₂ in the presence of pyridine leads to formation of mononuclear complexes [M(N^tBu)(NH^tBu)Cl₂Py₂],M = Nb ( 1 ), Ta ( 2 ). These new key compounds are characterized by ¹H, ¹³C NMR spectroscopy, mass spectrometry and elemental analyses. A single crystal structure analysis of [Ta(N^tBu)(NH^tBu)Cl₂Py₂] ( 2 ) reveals, that surprisingly chloro and not pyridine ligands are trans to the strongest π donor ligands [N^tBu]^2? and [NH^tBu]^?.     

Metal Chemical Vapor Deposition: Design and Synthesis of New Source Reagents for Osmium Thin Films

Treatment of β-diketone ligands, such as hfacH (hexafluoroacetylacetone) or tmhdH (2,2-dimethyl-3,5-heptanedione), with binary metal carbonyls Ru3(CO)12 or Os3(CO)12 in a stainless steel autoclave at elevated temperature afforded the corresponding mononuclear Ru or Os complexes 1, 2 and 3 in good yields. A second type of mononuclear Os CVD source reagent 4 has also been obtained from a reaction of Os3(CO)12 with 3 eq. of iodine under CO atmosphere. These four Ru and Os CVD source complexes are all relatively stable and highly volatile; thus, they can be utilized for depositing the respective metal thin-films with overall quality comparable or better than those deposited using the commercially available source reagents. The surface morphology, the purity and the crystallinity were identified by SEM micrograph, X-ray photoelectron spectroscopy, conductivity measurement and powder XRD, respectively. Possible reaction mechanisms leading to the formation of the metal deposit are presented.     

Low-Pressure Chemical Vapor Deposition of Silicon Carbide Thin Films from Organopolysilanes

(Me₃Si)₂SiMe₂, (Me₃Si)₃SiMe and (Me₃Si)₄Si were used as precursors for the deposition of polycrystalline β-SiC thin films on silicon substrates at 1000–1200°C in a low-pressure hot-wall chemical vapor deposition reactor. The thin films were analyzed by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy.     

化学气相沉积法合成二维过渡金属硫族化合物研究进展

二维晶体材料所独有的二维平面结构赋予了这类材料诸多独特的性质. 近年来围绕二维过渡金属硫族化合物的相关研究发展迅速. 本文以二维MoS₂、WS₂为代表概述了利用化学气相沉积法合成过渡金属硫族化合物二维晶体的研究进展, 阐述了基本合成策略, 讨论了主要影响因素, 归纳了以MoS₂、WS₂为结构基元的二维合金及异质结构的合成方法, 最后阐明了利用化学气相沉积法合成二维晶体存在的主要问题并展望了这一领域的发展前景.     

Volatile Heteroligand Complexes of Copper(II): New Precursors for Chemical Vapor Deposition of Copper Films

Two heteroligand ketoiminate–diketonate complexes of copper(II), CuL(hfa) (1), L = pentane-2-imino-4-onato, CH₃COCHCNHCH ₃ ^– , and CuL′(hfa) (2), L′ = 2,2,6,6-tetramethyl-3-iminoheptane-5-onato, C(CH₃)₃COCHCNHC(CH)^–, were studied as precursors for chemical vapor deposition of copper films. The flow method was employed to measure the temperature dependences of a saturated vapor pressure of these compounds, the thermodynamic parameters of evaporation–sublimation were calculated, and the volatilities of these compounds and thermal behaviors in the condensed and gaseous phases were compared. The copper films were compared, and it was shown that comparatively high growth rates are reached when (2) is used to obtain copper films in hydrogen.     

Chemical Composition and Structure of Thin Films Produced by Chemical Vapor Deposition

This paper reports results from studies of the chemical composition and structure of semiconducting, dielectric, and metallic films produced from molecular precursors by the chemical vapor deposition method. A study was made of films of zinc sulfides, mixed copper, cadmium, and zinc sulfides, boron nitride, carbonitride, silicon carbonitride, and iridium films. It is shown that the use of metal compounds with different ligands (zinc and manganese) enables production of zinc sulfide films in which manganese ions are uniformly incorporated into the zinc sulfide crystal lattice to substitute zinc at the lattice sites. For the films of simple and mixed cadmium, copper, and zinc sulfides, the film structure depends on the type of substrate. The thin layers of mixed cadmium and zinc sulfides are asubstitution solution with a hexagonal structure. The thin layers of boron nitride produced from borazine exhibit a nanocrystalline structure and are a mixture of cubic and hexagonal phases. Composite layers were produced from alkylamine boranes and their mixtures with ammonia. Depending on synthesis conditions, the layers are mixtures of hexagonal boron nitride, carbide, and carbonitride or pure boron nitride. Using silyl derivatives of asymmetric dimethylhydrazine containing Si—N and C—N bonds in the starting molecule, we produced silicon carbonitride films whose crystal habit belongs to a tetragonal structure with lattice parameters a = 9.6 and c = 6.4 . The iridium films obtained by thermal decomposition of iridium trisacetylacetonate(III) on quartz substrates in the presence of hydrogen have a polycrystalline structure with crystallite sizes of 50 to 500 . A method for determining grainsize composition was proposed, and grain shapes for the iridium films were analyzed. The influence of substrate temperature on the internal microstructure and growth of the iridium films is demonstrated. At the iridium–substrate interface, a transition layer forms, whose composition depends on the substrate material and deposition conditions.     

Plasma Enhanced Chemical Vapor Deposition of Fluorinated Amorphous Carbon Thin Films from Tetrafluoroethylene and Tetraisocyanatesilane

Fluorinated amorphous carbon films were prepared from tetrafluoroethylene (TFE; C₂F₄) and tetraisocyanatesilane (TICS; Si(NCO)₄) using an RF plasma enhanced chemical vapor deposition method for the purpose of application to inter layer low permittivity films used in large scale integrated circuits. Structure of the deposited films was investigated by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Adhesion characteristics were examined by a tape-peel method. Permittivity of the films was investigated from capacitance measurement on metal-insulator-semiconductor structure. The structural analysis revealed that the deposited films contained imide-like group in spite of the fact that TICS molecules contained isocyanate group . The films deposited under the flow ratio TICS/(TFE + TICS) = 70% showed permittivity of 2.3, good adhesion on silicon substrates, and higher thermal stability than the films deposited without TICS.     

Plasma-Enhanced Chemical Vapor Deposition of Silicon Carbonitride Films from Volatile Silyl Derivatives of 1,1-Dimethylhydrazine

Silicon carbonitride films were synthesized from new volatile precursors by plasma-enhanced chemical vapor deposition. Based on a detailed study of the morphology of film surfaces, it was found that the layer material was an amorphous matrix with inclusions of nanosized crystals. Calculation of the structure of the crystalline phase from synchrotron X-ray diffraction patterns demonstrated that the entire set of the diffraction peaks detected is indexed by a tetragonal structure with the lattice parameters a = 9.6 Å and c = 6.4 Å. This is consistent with the fact that the carbon 1s and nitrogen 1s core level X-ray photoelectron spectra exhibited only sp ³ bonding, which was expected for superhard carbon nitride phases.     

Color Reactions of Niobium and Tantalum with Bromine-Substituted Reagents of the PAR–PAN Group

Color reactions of niobium and tantalum with some heterocyclic azo reagents of the PAR–PAN group (2-(2-pyridylazo)-5-aminophenol, 2-(3,5-dibromo-2-pyridylazo)-5-aminophenol, and 2-(3,5-dibromo-2-pyridylazo)-5-diethylaminophenol) were studied. Quantitative characteristics of the reactions were determined, and conditions were found for the determination of small and large amounts of niobium and tantalum in the presence of each other using the 3,5-dibromo-PADAP reagent.     

Chemical Vapor Deposition of SnO2 Thin Films from Bis(β‐diketonato)tin Complexes

A series of bis(β‐diketonato)tin compounds have been systematically synthesized and examined as precursors for chemical vapor deposition of SnO₂ thin films. These complexes were characterized by elemental analyses and NMR, IR and mass spectroscopic methods. X‐ray single‐crystal determination of Sn(tfac)₂ reveals that the complex possesses a distorted trigonal bipyramidal structure. The SnO₂ films can be deposited on the substrates such as silicon, titanium nitride, and glass by using Sn(hfac)₂, Sn(tfac)₂ and Sn(acac)₂ as CVD precursors at deposition temperatures of 300‐600°C with a carrier gas of O₂. The deposition rates range from 20 to 600 Å/min. Deposited films have been characterized by XRD, SEM, AFM, AES and AAS analyses.     

以光辅助MOCVD法在有取向Ni衬底及LAO单晶衬底上制备YBCO外延膜的比较研究

采用光辅助金属有机物化学气相沉积(MOCVD)法,在生长有CeO2/YSZ/Y2O3(YSZ为Y稳定的ZrO2)缓冲层的双轴取向Ni衬底上进行了YBa2Cu3O7-x(YBCO)外延膜生长,并与LaAlO3(100)[LAO(100)]单晶衬底上的YBCO外延膜生长进行了对比.发现在Ni衬底上c轴取向YBCO外延膜的生长温度比LAO衬底上的生长温度低约30℃,但生长速度更快.经分析认为,这种差别主要是由于Ni衬底的热导率比LAO衬底高造成的.Ni衬底及LAO衬底上生长的c轴取向YBCO外延膜的超导极限电流密度(Jc)分别约为0.5 MA/cm2及1.8 MA/cm2.     

Polybromoaromatic Compounds: X. Reactions of Polybromobenzenes with Primary and Secondary Amines

Polybromobenzenes C₆Br₅X (X = Br, F, CN, NO₂) react with primary amines (methylamine and cyclohexylamine) to give nucleophilic substitution products; reactions of the same substrates with secondary amines (dimethylamine, diethylamine, piperidine, and morpholine) are accompanied by hydrodebromination processes.     

Electroluminescence and Photoluminescence of Conjugated Polymer Films Prepared by Plasma Enhanced Chemical Vapor Deposition of Naphthalene

Polymer light-emitting devices were fabricated utilizing plasma polymerized thin films as emissive layers. These conjugated polymer films were prepared by RF plasma enhanced chemical vapor deposition using naphthalene as monomer. The effect of different applied powers on the chemical structure and optical properties of the conjugated polymers was investigated. Fourier transform infrared (FTIR) and Raman spectroscopies confirmed that a conjugated polymer film with a 3-D cross-linked network was developed. By increasing the power, products tended to form as highly cross-linked polymer films. The fabricated devices showed broadband Electroluminescence (EL) emission peaks with center at 535–550 nm. Photoluminescence (PL) spectra of plasma polymers showed different excimeric emissions, resulted from crosslinked architecture. As the plasma power increased, the optical properties showed two different domains; up to 200 W, EL, PL and UV–Vis spectra red-shifted and broadened significantly. At higher powers, a reverse behavior was observed. Also, the relation between the film structure and plasma species was investigated using optical emission spectroscopy.     

ChemInform Abstract: Deposition of Aluminum Nitride Thin Films by MOCVD from the Trimethylaluminum-Ammonia Adduct.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Chemical Vapor Deposition of Phase‐Pure Uranium Dioxide Thin Films from Uranium(IV) Amidate Precursors

Homoleptic uranium(IV) amidate complexes have been synthesized and applied as single‐source molecular precursors for the chemical vapor deposition of UO₂ thin films. These precursors decompose by alkene elimination to give highly crystalline phase‐pure UO₂ films with an unusual branched heterostructure.     

Binary and Ternary Metal Complexes Derived from Cu Acetate with Some Sulfur-Containing Chemotherapeutic Agents

Two ternary complexes, [Cu₂(Pir)(Pen)(OH)(Ac)H₂O] and [Cu(Pir)(Cap)(Ac)] ½H₂O (where, Pen = D-penicillamine, Cap = captopril, and Pir = piroxicam) have been synthesized and characterized using elemental analyses, spectroscopic analyses (IR, UV-vis, MS), thermal analyses (TGA), conductance measurements, and magnetic measurements. The binary complexes, [Cu₂(Pen)(OH)₂(H₂O)₂] 4H₂O and [Cu(Cap)Ac] 3/2H₂O, have also been prepared and characterized by these techniques to facilitate the interpretation of the mixed ligand complexes. The results show that D-penicillamine can coordinate two copper atoms through amino nitrogen, and thiol sulfur after displacement of a hydrogen atom. At the same time, the ligand coordinates to the second copper atom through a carboxyl group after displacement of a hydrogen from the latter group. Captopril coordinates through thiol sulfur and carbonyl oxygen. Piroxicam coordinates as a neutral bidentate ligand in the keto form through carbonyl oxygen and pyridyl nitrogen. The magnetic moment measurements of complexes containing captopril indicate the reduction of Cu(II) to Cu(I) by the thiol group.     

Chemical Mechanism of the Solid-Phase Extraction of Metal Complexes: Barium Complexes with Crown Ethers

The adsorption of barium complexes of dibenzo-18-crown-6 (DB18C6) and dicyclohexano-18-crown-6 (DCH18C6) ethers on alkylated silica gel in the presence of sodium dodecylsulfonate was studied. The adsorbent capacity for the barium complex of DCH18C6 was higher than that for the complex of DB18C6 by a factor of about 4. Depending on the proton-acceptor ability of the adsorbate, the surface layer of alkyl radicals and residual silanol groups behaves as a solid surface or a liquid phase. In the latter case, a supramolecular cavity complementary to the adsorbate is formed in the surface phase. Thus, alkylated silica gel undergoes self-organization with regard to the properties of the adsorbate. This hypothesis explains the unusual adsorption of barium complexes.     

Growth Modes of SiO x Films Deposited by Evaporation and Plasma-Enhanced Chemical Vapor Deposition on Polymeric Substrates

In order to study the very first stages of plasma-enhanced chemical vapor deposition (PECVD) of SiO₂ on polymer substrates, we used a distributed electron cyclotron resonance (DECR) reactor, with the substrate placed (I) in the active glow zone, (II) downstream therefrom, and (III) downstream, but shielded from photon emission (e.g., VUV) from the plasma. For comparison, we also study films deposited by physical vapor ddposition (PVD, thermal evaporation). To characterize the ultra-thin deposits, we used oxygen plasma etching combined with scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Rutherford backscattering spectroscopy (RBS). We elucidate the roles of various energetic species (VUV photons, ions, atomic oxygen, and other radicals) in the plasma during the earliest growth phase, and the origin of the interphase which is present between the deposited SiO₂ and the polymer substrate.