A new fabrication technology for producing hypertextured aluminum-copper (Al-Cu) films has been developed. The key feature of this technology is the argon (Ar) plasma treatment of the titanium (Ti) underlayer. The full width at half-maximum values of the Al (111) rocking curve decrease with increasing Ti etched thickness. That is, the texture of the Al-Cu film improves with increasing Ti etched thickness. The Ti surface treated with Ar plasma has a high surface energy because the Al island wetting angle is small. We think this means the Ar-plasma-treated Ti surface structure is amorphouslike and rough. Consequently, highly preferred (111) texture Al-Cu films were obtained with argon plasma treatment of the Ti underlayer. The electromigration (EM) lifetime of these films is one order of magnitude higher than that of films obtained without the plasma treatment. The longer EM lifetime of the hypertextured Al lines is considered to be due to the small grain-boundary diffusivities for the bamboo microstructure. The argon plasma treatment of the titanium underlayer, combined with Al-Cu deposition, makes it possible to form highly EM-resistant multilevel interconnections without any of the drawbacks of the conventional method.