Shiow-Huey Chuang

Comparison of the diffusion barrier properties of chemical‐vapor‐deposited TaN and sputtered TaN between Cu and Si

This work investigated the barrier properties of metalorganic chemical‐vapor‐deposited (CVD) tantalum nitride (TaN) and physical‐vapor‐deposited (PVD) TaN between Cu and Si. The CVD TaN film had a preferred orientation (200) with a grain size of around 60 nm, while the PVD TaN had a (111) preferred orientation with a grain size of around 20 nm, as determined by transmission electron microscopy (TEM) and x‐ray diffraction (XRD) analyses. Degradation study of the Cu/TaN/Si contact system was also performed by sheet resistance measurement, scanning electron microscopy (SEM), XRD, secondary ion mass spectroscopy (SIMS), and shallow junction diodes. These results indicated that the PVD TaN film can act as a better diffusion barrier than the CVD TaN film. The higher thermal stability of PVD TaN than CVD TaN can be accounted by their difference in microstructures. The failure mechanisms of both CVD TaN and PVD TaN films as diffusion barriers between Cu and Si were also discussed.

Metalorganic chemical vapor deposition of tantalum nitride by tertbutylimidotris(diethylamido)tantalum for advanced metallization

We deposited tantalum nitride (TaN) films by low‐pressure metalorganic chemical vapor deposition (LP‐MOCVD) using a new precursor tertbutylimidotris(diethylamido)tantalum (TBTDET). Strong Ta–N double bond in the precursor preserved the ‘‘TaN’’ portion during the pyrolysis process. This method has yielded low‐resistivity films. It changed from 10 mΩ cm (deposited at 500 °C) to 920 μΩ cm (obtained at 650 °C). The carbon and oxygen concentrations were low in the films deposited at 600 °C, as determined by x‐ray photoelectron spectroscopy. Transmission electron microscopy and x‐ray diffraction analysis indicated that the as‐deposited films exhibited polycrystalline structures with the lattice constants close to the bulk TaN value. The TaN barrier layer was successfully applied as a glue layer for CVD tungsten (W) metallization schemes.

Metalorganic chemical vapor deposition of tungsten nitride for advanced metallization

In this study, the physical and electrical properties of tungsten nitride thin films deposited by thermal decomposition of bis(tertbutylimido)bis(tertbutylamido)tungsten have been investigated. The films have an excellent step coverage over high aspect‐ratio contact holes as well as a low carbon concentration. Strong W–N double bonds in the precursor preserved the nitrogen atoms during the pyrolysis process. This method subsequently yielded low‐resistivity films. A decrease in film resistivity from 4300 to 620 μΩ cm corresponded to an increase in the deposition temperature from 500 to 650 °C. X‐ray diffraction (XRD) and wavelength dispersive spectroscopy (WDS) results indicated that the as‐deposited films have face centered cubic (fcc) phase polycrystalline structures with excessive nitrogen atoms.

Syntheses and characterization of organoimido complexes of tantalum; potential single-source precursors to tantalum nitride

Abstract New single-source precursor to tantalum nitride thin films, (But N)Ta(NEt2)3, and relate complexes, (RN)Ta(NEt2)3 (R = Pri and Prn), were prepared by reacting corresponding (RN)TaCl3py2 complexes (R = But, Pri and Prn) with LiNEt2 in hydrocarbon solvents. The structure of (ButN)TaCl3py2 was determined by X-ray crystallography.

Fluorinated aminoalkoxide CuII complexes: new CVD precursors for deposition of copper metal

Volatile low-melting CuII metal complexes of formula Cu[OC(CF3)R1CH2NHR2]2 (R1 = CF3 or CH3; R2 = CH2CH2OMe, Bui, or But) and Cu[OC(CF3)R1CH2NMe2]2 (R1 = CF3 or CH3) have been synthesized and characterized by spectroscopic methods. A single-crystal X-ray diffraction study on Cu[OC(CF3)2CH2NHCH2CH2OMe]2 shows that one methoxyethyl group of the aminoalkoxide ligand forms an intramolecular dative bond to the Cu atom to produce a square-pyramidal geometry at the metal center, while the second is linked to the Cu atom of the adjacent molecule, giving an N2O4 octahedral coordination arrangement. For the second Bui-substituted complex, Cu[OC(CF3)2CH2NHBui]2, the X-ray structural analysis demonstrated an N2O2 square-planar geometry, with one alkoxide oxygen atom forming strong H-bonding to an adjacent water molecule. Metal CVD experiments were carried out, showing that the source reagents Cu[OC(CF3)2CH2NHBui]2, Cu[OC(CF3)2CH2NHBut]2, and Cu[OCMe(CF3)CH2NHBui]2, which possess a secondary amino group, are capable of depositing copper metal at temperatures of 250–300 °C under inert Ar carrier gas, while Cu[OCMe(CF3)CH2NMe2]2, with a tertiary amine group, requires the use of reductive H2 carrier gas to induce metal deposition at lower temperatures.

Formation of mononuclear nitrido complexes of chromium(VI) and molybdenum(VI); syntheses and X-ray crystal structures of NCr(OBut)3 and NMo(OSiMe3)3(py)

Mononuclear nitrido complexes of Cr and Mo, NCr(OBut)3 and NMo(OSiMe3)3(py), are synthesized; the chromium complex has an idealized C3ν symmetry while the molybdenum complex has a distorted square-pyramidal geometry with the nitrido ligand at apical position; the N–Cr distance is 1.538(5)A while the average N–Mo distance is 1.627 A.

DEPOSITION OF MOLYBDENUM CARBONITRIDE THIN-FILMS FROM MO(NBUT)2(NHBUT)2

Mo(NBu t ) 2 (NHBu 1 ) 2 is used as a single-source precursor to deposit thin films of cubic phase molybdenum carbonitride, MoC x N y ( x : 0.2-0.55, y : 0.1-0.47), by chemical vapor deposition on silicon substrates. In general, the C/Mo ratios increased from 0.2 to 0.55 and the N/Mo ratios decreased from 0.47 to 0.1 with increasing the temperature of deposition from 773 to 923 K. Based on the elemental composition and the composition of the gas phase products, it is proposed that the carbon atoms were incorporated through β-methyl activation of the ligands.

A novel synthesis of organoimido complex by transamination action. X-ray cyystal structure of a bis-(isopropylimido) complex of tungsten(VI), [W(μNPri)(NPri)(NHPri)2]2

Abstract The bis(isopropylimido) complex [W(μ-NPri)(NPri)(NHPri)2]2 was synthesized by reacting W2(NBut)2(NHBut)2 with excess PriNH2. The complex, characterized by X-ray crystallography, is a dimer of distorted trigonal bipyramids sharing an edge defined by the unsymmetrical bridging imido ligands. Exchange between the bridging and the terminal imido ligands were observed on the NMR timescale, ΔG‡ = 14.5 ± 1.0 kcal mol−1. An equilibration process is proposed to account for the fluxional behaviour.