Tungsten nitrido complexes of the form WN(NR2)3 [R = combinations of Me, Et, (i)Pr, (n)Pr] have been synthesized as precursors for the chemical vapor deposition of WN(x)C(y), a material of interest for diffusion barriers in Cu-metallized integrated circuits. These precursors bear a fully nitrogen coordinated ligand environment and a nitrido moiety (W≡N) designed to minimize the temperature required for film deposition. Mass spectrometry and solid state thermolysis of the precursors generated common fragments by loss of free dialkylamines from monomeric and dimeric tungsten species. DFT calculations on WN(NMe2)3 indicated the lowest gas phase energy pathway for loss of HNMe2 to be β-H transfer following formation of a nitrido bridged dimer. Amorphous films of WN(x)C(y) were grown from WN(NMe2)3 as a single source precursor at temperatures ranging from 125 to 650 °C using aerosol-assisted chemical vapor deposition (AACVD) with pyridine as the solvent. Films with stoichiometry approaching W2NC were grown between 150 and 450 °C, and films grown at 150 °C were highly smooth, with a RMS roughness of 0.5 nm. In diffusion barrier tests, 30 nm of film withstood Cu penetration when annealed at 500 °C for 30 min.

The effect of proximal Zn halides on Ni-catalyzed ethylene polymerization is reported in this work. A series of (NON)NiLX (NON = 2,6-bis-((2,6-diisopropylphenyl)imino)methyl phenoxide; LX = methallyl or L = py, X = tolyl, 2-4) ethylene polymerization precatalysts have been synthesized, as well as a heterobimetallic Ni/Zn complex, (NON)Ni(CH)ZnBr (5). Each precatalyst could be activated (or promoted) by ZnX (X = Cl, Br, Et) to polymerize ethylene. In situ recruitment of ZnX by the free imine binding pocket of the NON complexes results in the generation of heterobimetallic active species that produce lower M polyethylene than monometallic controls. Room temperature ZnX-promoted polymerizations with these catalysts resulted in bimodal M distributions that result from different catalyst speciation: "dangling" imine-ligated ZnX species yield higher M polymer while N,O-chelated ZnX species yield lower M polymer. Running polymerizations at higher temperature yields in only lower M polymer resulting from exclusive formation of the thermodynamically favored N,O chelated Ni/Zn heterobimetallic. DFT calculations indicate that this bridging bimetallic complex undergoes β-H elimination more facilely than monometallic Ni analogues, resulting in lower molecular weight polymers.

Deposition of high quality WN x C y barrier films at very low temperature using aerosol-assisted chemical vapor deposition (AACVD) is reported. The single-source tungsten nitrido complex, WN(NEt 2 ) 3 , was designed to reduce the temperature required for WN x C y film deposition in an effort to minimize thermal stresses on neighboring layers in device structures. Using either pyridine or heptane as a solvent, WN x C y films were successfully deposited at temperatures from 100 to 650 • C. Film growth in pyridine and heptane at low temperature (100-350 • C and 125-550 • C, respectively) showed weak temperature dependence consistent with mass-transfer limited growth. At higher temperature the growth rate decreased rapidly with apparent activation energy of 0.375 ± 0.057 eV. The effects of solvent choice on film properties including composition, crystallinity, density, and surface roughness are discussed. Films deposited at low temperature (<350 • C) were highly smooth, amorphous and with a stoichiometry approaching W 2 NC; characteristics desirable for diffusion barrier applications. In Cu diffusion barrier tests, Cu (∼ 100 nm)/WN x C y (∼ 5.5 nm)/Si stacks subjected to a 500 Thin interlayer materials are increasingly being used in electronic devices to modify interfacial characteristics, including the film work function, chemical, thermal and charge transport rates, surface tension, and adhesion. Due to their low resistivity, appropriate work function, and thermal stability, refractory metal nitrides have been proposed for a number of applications, ranging from wafer level hermetic sealing 1 to field effect transistor (FET) gate electrodes. 2 In particular, the tungsten-based materials WN x and WN x C y have been considered as an alternative for both diffusion barriers 3,4 and gate electrodes 5 due to their low resistivity, appropriate and tunable work function (4.39-5.01 eV 6 ), thermal and mechanical stability, good barrier performance, and processing simplicity. 7,8 Depositions of WN x and WN x C y typically use ammonia and WCl 6 , WF 6 or W(CO) 6 as co-reactants. 4,[9][10][11][12] Despite being volatile, simple, and cost-effective, these chemistries generally require high deposition temperature, can introduce impurities, and can yield corrosive byproducts. To overcome these drawbacks, organometallic precursors have drawn considerable interest for metal-organic CVD (MOCVD). Typically, these complexes include nitrogen-bound moieties such as amido, imido, hydrazido, amidinate or guanidinate ligands, 13,14 and have been used in single-source or NH 3 /H 2 co-reacting conditions to deposit WN x . Unfortunately, many of these precursors still require relatively high deposition temperature (>350• C) 15-22 that can compromise contact level structures 2,23 and neighboring dielectrics. 24In addition, the development of ultra-low temperature CVD WN x C y has potential application to flexible and organic devices. Therefore, there is interest in developing organometallic precursors for ultra-low deposition temperature. We h...

Tungsten nitrido complexes of the type WN­(NR2)3 [NR2 = combinations of NMe2, NEt2, N i Pr2, N n Pr2, N i Bu2, piperidine, and azepane] were synthesized as precursors for aerosol-assisted chemical vapor deposition of WN x C y thin films. The effects of the amido substituents on precursor volatility and decomposition were evaluated experimentally and computationally. Films deposited using WN­(NMe2)­(N i Pr2)2 as a single-source precursor were assessed as diffusion barrier materials for Cu metallized integrated circuits in terms of growth rate, surface roughness, composition, and density. In diffusion barrier tests, Cu (∼100 nm)/WN x C y (∼5 nm)/Si samples prepared from WN­(NMe2)­(N i Pr2)2 were annealed for 30 min at 500 °C and successfully blocked Cu penetration according to four-point probe, X-ray diffraction, scanning electron microscopy etch-pit test, and high-resolution transmission electron microscopy measurements.

Design of precursors for thin film growth by chemical vapor deposition (CVD) can be informed by knowledge of the precursor decomposition mechanism. However, the vast majority of decomposition characterization is done by techniques that do not capture CVD conditions. This work used a custom CVD reactor with in situ Raman spectroscopy capabilities to investigate the gas phase thermal decomposition of the tungsten imido complex Cl4(CH3CN)WNiPr, a known precursor for the aerosol‐assisted (AA)CVD of tungsten carbonitride thin films. In combination with previous computational and ex situ data, we propose a decomposition mechanism for this precursor under CVD conditions, based on observation of gas phase products of N(imido)‐C bond homolysis and σ‐bond metathesis between the precursor W–Cl bond and H2.