Paper TF-ThP17
Atomic Layer Deposition of Lanthanum Based Oxides for High-K Gate Dielectrics

Thursday, October 23, 2008, 6:00 pm, Room Hall D

Lanthanum oxide (La₂O₃) is gaining importance as one of the promising high-k candidates due to its superior properties such as a high dielectric constant (~27), large band gap and high electrical breakdown field strength. However, the hygroscopic properties of La₂O₃ leads to the formation of lanthanum hydroxide (La(OH)₃) which causes deterioration of electrical properties such as, permittivity. Additionally, several studies have reported that a La based CVD process result in a high C concentration in the deposited films. In order to overcome these issues, we investigate two different processes; one is alternating layers of La₂O₃ and Al₂O₃ to form nano-laminate (La_xAl_yO₃) structures and the other is employing ozone as the oxidant. In this study, we deposited La_xAl_yO₃ films using atomic layer deposition (ALD) on H-terminated p-type Si (100) substrate using tris(N,N’-diisopropylformamidinato) lanthanum, La(iPrfAMD)₃ as the La precursor while water and ozone employing as the oxidant. The physical properties of the deposited La-oxide using various characterization techniques such as HR-TEM, XPS, and XRD as well as electrical characteristics will be presented. Particularly, our in-situ XPS half-cycle study provides an insight on chemical composition modulation based on different process sequence. Acknowledgement: Rohm and Haas Electronic Materials, LLC. for financial support and Toshiba Mitsbushi Electric Industrial Systems Corporation (TEMIC) for providing a ozone generator (OP-H250 LT) for a high concentration ozone.