Effect of post-deposition annealing temperature on RF-sputtered HfO 2 thin ﬁlm for advanced CMOS technology A.G. Khairnar, A.M. Mahajan * Department of Electronics, North Maharashtra University, PB No-80, Umavinagar, Jalgaon 425001 (M.S.), India article info Article history: Received 1 February 2012 Received in revised form 15 August 2012 Accepted 22 September 2012 Available online 29 September 2012 Keywords: High-k HfO 2 RF-sputtering FTIR AFM D it IV/CV abstract Structural and electrical properties of HfO 2 gate-dielectric metal-oxide-semiconductor (MOS) capacitors deposited by sputtering are investigated. The HfO 2 high-k thin ﬁlms have been deposited on p-type <100> silicon wafer using RF-Magnetron sputtering technique. The Ellipsometric, FTIR and AFM char- acterizations have been done. The thickness of the as deposited ﬁlm is measured to be 35.38 nm. Post deposition annealing in N 2 ambient is carried out at 350, 550, 750  C. The chemical bonding and surface morphology of the ﬁlm is veriﬁed using FTIR and AFM respectively. The structural characterization conﬁrmed that the thin ﬁlm was free of physical defects and root mean square surface roughness decreased as the annealing temperature increased. The smooth surface HfO 2 thin ﬁlms were used for Al/HfO 2 /p-Si MOS structures fabrication. The fabricated Al/HfO 2 /p-Si structure had been used for extracting electrical properties such as dielectric constant, EOT, interface trap density and leakage current density through capacitance voltage and current voltage measurements. The interface state density extracted from the GeV measurement using Hill Coleman method. Sample annealed at 750  C showed the lowest interface trap density (3.48  10 11 eV 1 cm 2 ), effective oxide charge (1.33  10 12 cm 2 ) and low leakage current density (3.39  10 9 A cm 2 ) at 1.5 V. Ó 2012 Elsevier Masson SAS. All rights reserved. 1. Introduction In advanced semiconductor technology, the transistor gate length will continue to shrink and reaches sub-20 nm by 2015 in order to achieve faster switching speed and higher device density. The corresponding impact would be the reduction of gate length and gate oxide thickness to 1.5 nm. However, with the advent of gate length technology to 45e22 nm node, ultimate oxide scaling down to EOT of approximately 0.5 nm is required [1,2]. As the size of gate oxide thickness continues to scale down, the use of conventional SiO 2 as a gate dielectric material is approaching physical and electrical limits such as problems of gate leakage current due to direct tunneling of electrons and gate dielectric reliability. To overcome these issues, much interest in high-k materials as the potential gate dielectrics beyond 45 nm tech- nology nodes has been developed [3e5]. A variety of high- dielectric metal oxides have been intensely studied during the last decade such as Al 2 O 3 [6,7], HfO 2 [8], TiO 2 [9], CeO 2 [10], LaAlO 3 [11], HfSiO [12], ZrO 2 [13] etc. High dielectric materials are also drawing increasing interest as MIM capacitor for analog/mixed signal and RF integrated circuit application due to their downward scaling of the capacitor area with the higher capacitance density. Among a range of high-k materials HfO 2 has emerged as the most potential high-k dielectric, as it has high dielectric constant (20e25), high band gap (5.8 eV), high heat of formation (271 K cal/mol), compatibility with poly-silicon gate process, good thermal stability with silicon, low density of interface states and good electrical reliability [14e16]. HfO 2 is also potential candidate for several other applications such as gas sensing devices, tunnel junctions, laser damage-resistance optical coatings and thin ﬁlm capacitors [17]. As gate oxide is the most vital constituent of a MOS structures, extremely reliable high quality high-k gate dielectric thin ﬁlms are essential. For this reason gate oxide ﬁlm growth is a very important issue and as such received considerable interest. Variety of thin ﬁlm deposition techniques such as atomic layer deposition (ALD), molecular beam-epitaxy (MBE), pulsed-laser deposition (PLD), chemical vapor deposition (CVD), reactive thermal evaporation [18] have been used to achieve good quality of high-k thin ﬁlms. RF sputtering [19] is PVD based technique combined with plasma offers a low temperature processing and blocks the oxygen from the ambience, which prevent the * Corresponding author. Tel.: þ91 257 2257476; fax: þ91 257 2258406. E-mail address: ammahajan@nmu.ac.in (A.M. Mahajan). Contents lists available at SciVerse ScienceDirect Solid State Sciences journal homepage: www.elsevier.com/locate/ssscie 1293-2558/$ e see front matter Ó 2012 Elsevier Masson SAS. All rights reserved. http://dx.doi.org/10.1016/j.solidstatesciences.2012.09.010 Solid State Sciences 15 (2013) 24e28