Resistless patterning of aluminum

A technique for patterning and depositing aluminum using laser-assisted selective chemical vapor deposition (CVD) is presented. This is accomplished using a light-assisted process that activates an adsorbed metallorganic precursor for aluminum, dimethyl-aluminum hydride (DMAlH), onto the substrate surface, thus forming a seed layer for subsequent selective CVD. In the same processing chamber, once the patterning is delineated via this seed layer, the substrate temperature is raised to 110-180°C, and selective CVD of aluminum takes place. A report is presented on the issues of selectivity, growth rates, morphology, electrical properties, and elemental composition of aluminum grown in this manner. Electrical resistivity, for example, can be as low as twice that of bulk aluminum. Furthermore, in order to make such a process compatible with multilevel metallization schemes, contact resistivity of such a film to preexisting aluminum metallization (with a native aluminum oxide) was measured and found to be ~0.2 μΩ-cm ² without any special pre- or post-treatment. Previous attempts at such a deposition and patterning scheme were less than successful at obtaining reliably low contact resistivities