In situ, real-time observation of Al chemical-vapor deposition on SiO ₂ in an environmental transmission electron microscope

A technique for in situ observation of chemical-vapor deposition (CVD) is demonstrated. An environmental transmission electron microscope with 3.8 Å resolution was used for real-time, in situ observation of Al CVD onto SiO ₂ from trimethylamine alane (TMAA). Nominal TMAA pressures from 50 to 400 mTorr and substrate temperatures from 50 to 200 °C were investigated for deposition onto both TiCl₄ pretreated and untreated surfaces. For deposition onto untreated surfaces, low nucleation densities and polycrystalline, dendritelike growth were observed for all deposition temperatures with deposition commencing at about 150 °C. Deposition on TiCl₄-treated surfaces resulted in polycrystalline films with grain sizes of a few nm and lower-temperature (100 °C) growth.