Effect of barium contamination on gate oxide integrity in high-k dram

• Published in: Journal of non-crystalline solids Vol. 303; no. 1; pp. 12 - 16
• Main Authors: Boubekeur, H., Mikolajick, T., Bauer, A., Frey, L., Ryssel, H.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.05.2002; Elsevier
• Subjects: Applied sciences; Electronics; Exact sciences and technology; Integrated circuits; Integrated circuits by function (including memories and processors); Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; D180; D110; Degradation; Diffusion profile; Barium addition; Time of flight method; Gate oxide; Electric stress; Random access memory; Dynamical storage; Secondary ion mass spectrometry; Leakage current; Reliability; Contamination
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/S0022-3093(02)00957-2

Barium impact on the gate oxide breakdown was studied using E-ramp and constant current stress (CCS) charge to breakdown. Wafers were contaminated with Ba after a 7.5 nm gate oxide growth and 300 nm poly-silicon deposition. The measurements were done on capacitors having areas of 0.1, 1, 4, and 16 mm2. Up to a contamination level of 4×1014 atoms/cm2 no degradation in oxide integrity was observed either by E-ramp or CCS. Time of flight (ToF)-SIMS measurement of Ba diffusion profile at 800 °C shows a diffusion of Ba over distances of some tens of nanometers, thus Ba does not reach the gate oxide region. The effect on the gate oxide breakdown can be correlated with the slow diffusion of Ba in poly-Si. Therefore, no major concern of yield and reliability due to Ba contamination is seen for the integration of Ba containing dielectrics into memories.