COPPER CONTAMINATION EFFECTS IN 0.5 MU-M BICMOS TECHNOLOGY

Copper is attracting increasing interest as a material for interconnec tions in future high speed ULSI circuits because of its low electrical resistivity and high electromigration performance [1]. Obviously, cop per metallization has entered the stage of application in future ULSI fabrication [2]. However, the possibility of using for as long as poss ible the same processing equipments for the fabrication of circuits wi th either the standard Al-based or new copper metallization could be a major issue for circuit manufacturers. CMOS and bipolar test-circuits were used to detect the effects of Cu cross-contamination that could occur in equipment used for the fabrication of both Al-based and Cu in terconnections. This paper describes the effects of such a contaminati on for typical thermal annealings used during backend processing. The diffusion barrier ability of a thin TiN film deposited at the backside of the Si substrate is also demonstrated.