A new gas phase pretreatment method was developed for blanket Al chemical vapor deposition (CVD) used in ultralarge-scale integration metallization. This method uses a halogen-free Ti compound. The pretreatment process involves exposing substrates to a tetrakisdimethylamino-titanium atmosphere before the Al CVD. This significantly lowers the deposition temperature of CVD using dimethylaluminum-hydride, and thus Al films can be deposited on SiO2 even at 160 degrees C, where deposition would otherwise not occur. The deposited AZ films have superior surface morphology due to higher Al island density in the early growth stage. Using this technique, V-shaped trenches with an opening width of 0.4 mu m and a depth of 1.2 mu m are successfully filled with Al.