We report integration of metal organic chemical vapor deposition (MOCVD) TiSiN barrier metal into 65 nm low-k dielectric (k=2.9) interconnects. Selective TiSiN barrier was formed along via trench wall using direct contact via (DCV) process and subsequent Ta incorporation into Cu was found to significantly improve electromigration (EM) reliability. Also, a large reduction of 0.1 µm via/line resistances is achieved. The proposed integration method allows MOCVD TiSiN usable as a barrier metal for the nano scale interconnects, taking advantages of high throughput and excellent step coverage of MOCVD process compared to other barrier processes.

The barrier metal properties of Plasma Enhanced ALD (PEALD) TaN deposited on low-k dielectric film (SiCOH) with a k value of 3.0 at a deposition temperature of 300°C by using pentakis (ethylmethylamino) tantalum (PEMAT) and various plasma gases was investigated. The film resistivity of TaN is about 1000 μΩ.cm under the plasma power of 200 W and the frequency of 400 KHz, respectively. The resistivity was significantly reduced by approximately 360 μΩ.cm for the optimized condition of 300 W and 13.56 MHz. In addition, good uniformity was obtained by applying two-step plasma treatment process. The film thickness per cycl of the TaN using two-step plasma was decreased from 1.0 Å to 0.65 Å by reducing a base pressure, indicating the increase of the film density. The PEALD TaN with almost 100% coverage in this paper's dual damascene structure has a contact resistance of about 1.6 Ω /chain at via size of 0.19um.

Integration of MOCVD TiSiN barrier metal with low-k dielectric layer (k=2.9) has been successfully demonstrated for 65 nm technology. By eliminating TiSiN barrier at via bottom prior to Cu via formation using Direct Contact Via (DCV) process, electromigration (EM) reliability of the TiSiN barrier was found to be substantially improved. Also, a significant reduction of 0.1 um via/line resistances is achieved. The proposed integration method allows MOCVD TiSiN barrier usable for nano interconnect, being able to take advantage of high throughput and excellent step coverage of MOCVD process.