Homogeneous Decomposition of Aryl- and Alkylimido Precursors for the Chemical Vapor Deposition of Tungsten Nitride:  A Combined Density Functional Theory and Experimental Study

Abstract

MOCVD growth of tungsten nitride (WN(x)()) and tungsten carbonitride (WN(x)()C(y)()) thin films has been reported from the complexes Cl(4)(CH(3)CN)W(NR) (1: R = Ph; 2: R = (i)Pr; 3: R = C(3)H(5)). To evaluate the role of the imido substituent in film growth, gas-phase homogeneous decomposition of precursor molecules was investigated using density functional theory (DFT) calculations. Computational results and NMR kinetics of acetonitrile exchange by 2 in solution verified that dissociation of the acetonitrile ligand should be facile for 1-3 in the temperature range used for film growth (>450 degrees C). A computational search for transition states for cleavage of W-Cl bonds in the presence of H(2) carrier gas was consistent with a sigma-bond metathesis pathway. Natural bonding orbital (NBO) analysis and bond energy calculations indicated that 1 has a stronger N-C(imido) bond and a slightly weaker W-N bond than 2 and 3, suggesting a greater role for W-N bond cleavage in depositions from 1. These results are consistent with mass spectrometric fragmentation patterns from 1-3 and low nitrogen content in films deposited from 1 as compared to those from 2 and 3.

Computational study on transamination of alkylamides with NH3 during metalorganic chemical vapor deposition of tantalum nitride

“…To minimize computational time, the simpler TBTDMT was chosen as a model for Ta alkylamides. Computational time was also a factor in the choice of the 6-31G(d) basis set for non-tantalum atoms, although it should be noted that results from this basis set may overestimate the calculated DH1 and DH1 ,z by several kcal/mol, compared to calculations using more elaborate basis functions (e.g., 6-311G(d) or 6-31G(d,p)) [15,18]. Regarding the spin multiplicity, the singlet state is a lot more stable than the triplet state for all the cases.…”

Novel pseudo-morphotactic synthesis and characterization of tungsten nitride nanoplates

“…The similar examples can be found in references [34,35,37], where gaseous NH 3 or N 2 are used as the nitridizing agents. However the cases of ammonium dicyanamide [36], and ALD or CVD methods [22][23][24][25][26][27][28][29], other WN x phases are obtained. This may give us a clue that the state of the nitridizing agents and synthetic processes may account for the difference in the product phases, but further work is needed for deep understanding of the related mechanism.…”

“…Atomic layer deposition (ALD) method is one of the most efficient routes to fabricate WN x C y films [22,23] and WN x films [20,24,25] on various surfaces, due to its ability of precise control of film thicknesses [13]. Chemical vapor deposition (CVD) [11], metalorganic CVD (MOCVD) method [26,27], and plasma-enhanced chemical vapor deposition [28] are frequently used to synthesize WN x C y , WN 1.5 O 0.1 and WN x thin films. DC reactive magnetron sputtering [29], reactive r.f.…”

Manganese Precursor Selection and the Thermal Atomic Layer Deposition of Copper/Manganese Alloy Films

“…In addition, barrier layers must be  2 nm thick to reduce the electrical resistivity of the interconnect structure and to fit inside sub-22 nm device features (1)(2)(3)(4)(5)(6). TaN and WNx (x = 0.5-1) films are currently used as Cu barrier layers (7)(8)(9). However, these materials may not serve as effective Cu diffusion barriers at thicknesses of  5 nm (2)(3)(4)(5).…”