Surface morphology improvement of metalorganic chemical vapor deposition Al films by layered deposition of Al and ultrathin TiN

The surface morphology of aluminum (AI) films grown by metalorganic chemica l vapor deposition (MOCVD) has been improved by inserting a 1.0-nm-thick ti tanium nitride (TiN) layer between 90-nm-thick Al layers. For multilayered Al/TiN film depositions, dimethylaluminum-hydride (DMAH) and tetrakis(dimet hylamido)titanium (TDMAT) are used as metalorganic precursors. For uniform and conformal. TiN layers 1.0-nm-thick atomic layer deposition (ALD) was ca rried out in the same reaction chamber as the Al MOCVD. The surface morphol ogy of the films was evaluated by measuring-the optical reflectance. In the early stage of Al MOCVD, the reflectance versus film thickness curve shows a rapid decrease because of the scattering of incident light from the Al n uclei, and then it increases sharply to a maximum reflectance until the com pletion of island coalescence. However, it monotonically decays again with Al thickness due to the nonuniform grain growth. By inserting a 1.0 nm TiN layer on the Al layer at the maximum reflectance, the reflectance is restor ed again to the peak reflectance in the manner of a sinusoid waveform. More over, the multilayered Al/TiN films have a strong (111) preferred crystal o rientation, and small and uniformly sized Al grains, which are expected to result in higher electromigration resistance. Therefore, the combined depos ition technique with Al MOCVD and TiN ALD is considered a promising candida te to make Al MOCVD suitable for future microelectronic applications.