Guanidinato-based precursors for MOCVD of metal nitrides (M_xN: M = Ta,W)

Refractory metal nitrides such as TaN and W_xN are interesting candidates as novel gate electrodes in CMOS technology. MOCVD and, in particular, ALD are desirable deposition processes and the development of new complexes and the precursor chemistry plays a vital role. We are interested in fine-tuning the properties of key precursors by ligand variation and introducing the chelating all-nitrogen coordinating groups such as guanidinato and β-diketiminato ligands. Guanidinato ligand-based complexes of groups V and VI, especially Ta, and W are interesting precursors for MOCVD and ALD of respective metal nitride thin film growth. As a representative example, evaluation of Ta- and W-based guanidinato complexes as MOCVD precursors and thermal analysis of the new complexes by TG-DTA analysis will be presented. The MOCVD of TaN, W_xN thin film growth using our novel mixed ligand precursors and the film characterization by XRD, SEM, cross-sectional SEM, SNMS and conductivity measurements (four-point probe analysis) is discussed in detail. Ta-guanidinato complexes were also used as a single source precursor for MOCVD of TaN. Nearly stoichiometric cubic TaN films with very less carbon content were obtained with good conductivity values.