| The semiconductor industry is transitioning from aluminum to copper as the interconnect material for integrated circuits. Diffusion barriers are essential for preventing copper migration into silicon in the resulting integrated circuits. Metalorganic chemical vapor deposition (MOCVD) is a useful technique for conformal deposition of thin barrier films. By manipulating the molecular structure of the MOCVD precursor(s), it is possible to control the structure and properties of the deposited film.; The focus of this work has been to examine novel precursors for use in MOCVD of thin film diffusion barriers. To date, the suitability of a variety of novel precursors for deposition of tungsten nitride (WNx) for diffusion barrier applications has been tested. The WNx precursors were of the form Cl4(CH3CN)WNR, where R represents the isopropyl, phenyl, and allyl group, among others. Mass spectrometry fragmentation patterns for each precursor were studied to pre-screen candidate precursors. Film properties were examined by several different characterization techniques, including XRD, AES, XPS, SEM, and 4-Point Probe. Data from these techniques were then correlated to pre-screen fragmentation patterns to determine the impact of the imido (R) group on film deposition. Apparent activation energies for film growth from the allyl, isopropyl and phenyl precursors, for example, were 0.15, 0.84 and 1.41 eV, respectively, and were directly related to the strength of the N-R bond in the precursors.; In addition to experimental testing of new precursors for WNx deposition, thermodynamic phase equilibria for the W-N-H-C-Cl deposition system was assessed. Modifications were made to the previously reported W-N binary model to include new experimental data from the literature on the desired FCC WNx phase as well as the SHP WN phase. Once the binary W-N diagram was reassessed, this model was merged with the existing W-H-C-Cl database to create an initial model for solid-gas equilibrium in our system at our experimental conditions. Using a combination of XRD, AES, and XPS data from our films, the W-N-H-C-Cl model was modified to include carbon-nitrogen-vacancy interactions in the face-centered cubic (FCC) WNxCy solid phase, so that the new model reflected our experimental results. Finally, the low-temperature ternary W-C-N phase diagram was predicted. |
