Barrier properties of Ta–RuO 2 diffusion barrier for dynamic random access memory capacitor bottom electrodes

• Published in: Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures 1999-07, Vol.17 (4), p.1470-1476
• Main Authors: Yoon, Dong-Soo, Baik, Hong Koo, Lee, Sung-Man, Lee, Sang-In
• Format: Article
• Language: English
• ISSN: 0734-211X; 1520-8567
• DOI: 10.1116/1.590776

We proposed the Ta–RuO 2 diffusion barrier for oxygen in the dynamic random access memory capacitor bottom electrode, and investigated the barrier and electrical properties of the developed diffusion barrier. The Ta–RuO 2 /TiSi 2 /poly-Si/SiO 2 /Si contact system deposited with and without the SiO 2 capping layer showed the lower total resistance and ohmic characteristics up to 800 °C. For the Ta–RuO 2 /TiSi 2 /poly-Si/SiO 2 /Si contact system, no other phases observed except for the formation of conductive RuO 2 phase in the barrier film by reaction with the indiffused oxygen after annealing in air, but the thin oxidized layer at the Ta–RuO 2 /TiSi 2 interface was formed by external oxygen. However, a large number of the crystallites in the annealed samples compared to that of as-deposited film were observed even after depth profile. The crystallites consisted of Ru and O containing a small amount of Ta. In addition, the embedded RuO 2 crystalline phase was observed in the thin oxidized TiSi 2 surface layer. Correspondingly, we suggest that the ohmic mechanism of the Ta–RuO 2 /TiSi 2 /poly-Si/SiO 2 /Si contact system is an embedded RuO 2 crystalline phase involving a small amount of Ta in a Ta amorphous structure.