Graded TiW Barrier Layer for Tailored Al-Cu Electromigration Resistance and TiW to Si Barrier Height Control
Original Publication Date: 1980-Dec-01
Included in the Prior Art Database: 2005-Feb-12
In semiconductor fabrication the Cr/Al-Cu first level metal interconnect scheme and the Ta/Cr/Al-Cu scheme have enhanced electromigration resistance due to Cr-Al interdiffusion and the formation of CrAl intermetallic within the Al-Cu current carrying metallization. One process [f] (e.g., referred to as a "hybrid process") uses sputtered TiW (10 wt.% Ti) as both the low barrier Schottky barrier diode (LBSBD) and the diffusion barrier. Since TiW is more resistant to interdiffusion with Al-Cu then Cr, little or no enhancement of the electromigration resistance of Al-Cu results; Al-Cu on TiW behaves similarly to Al-Cu on Si(3)N(4) or SiO(2). There is thus a need to develop an enhanced Al-Cu metallurgy. Various schemes have been successfully used previously to accomplish this.