Published in IET Microwaves, Antennas & Propagation Received on 29th January 2008 Revised on 29th April 2008 doi: 10.1049/iet-map:20070344 In Special Issue on Asia Pacific Microwave Conference 2007 ISSN 1751-8725 In situ microwave characterisation of medium-k HfO 2 and high- k SrTiO 3 dielectrics for metal – insulator– metal capacitors integrated in back-end of line of integrated circuits T.T. Vo 1 T. Lacrevaz 1 C. Bermond 1 T. Bertaud 1 B. Fle ´ chet 1 A. Farcy 2 Y. Morand 2 S. Blonkowski 2 J. Torres 2 B. Guigues 2 E. Defay ¨ 3 1 IMEP-LAHC, UMR CNRS 5130, Universite ´ de Savoie, 73376 Le Bourget du Lac Cedex, France 2 STMicroelectronics, 850 rue J. Monnet, 38926 Crolles Cedex, France 3 CEA-LETI, 17 rue des Martyrs, 38054 Grenoble, France E-mail: thierry.lacrevaz@univ-savoie.fr Abstract: Integration of high permittivity dielectrics or commonly named high-k dielectrics is widely investigated as a way to reduce passive component size in the chip. The complex permittivity microwave characterisation of medium-k materials such as HfO 2 and high-k materials such as SrTiO 3 is presented. The characterisation method, using coplanar, microstrip waveguides or metal–insulator–metal (MIM) capacitor, allows a large band characterisation, from 40 MHz to 40 GHz. It also allows investigating these materials with a large-scale thickness, from 10 up to 500 nm, in different technological configurations, appropriate for insulators from immature to mature, that is, those which are ready for the integration in an advanced damascene architecture of MIM capacitor. It is shown that the permittivity of such materials can be process- and frequency-dependent. 1 Introduction Medium-k and high-k materials are largely investigated as promising candidates for the insulating layer in metal– insulator–metal (MIM) capacitors in advanced integrated circuits as these materials lead to the increase in capacitance density. This density is expected to be 5 fF/mm 2 in 2010 as reported in the ITRS [1]. MIM capacitors are used for many applications: Radio frequency (RF), analogue mixed signal, decoupling capacitors or dynamic random access memory. MIM capacitors integration in the interconnect network of integrated circuits is a key point for the development of the system on chip. Medium-k such as hafnium oxide (HfO 2 ) or zirconium oxide (ZrO 2 ) presents many good performance: k-value from 15 to 35 at DC [2–6], high thermal stability in direct contact with silicon and good process compatibility [7]. Thanks to these qualities, HfO 2 and ZrO 2 are promising alternatives for both MIM and metal oxide semiconductor (MOS) structures [8, 9]. Other materials focusing many attentions are high-k such as strontium titanate (SrTiO 3 , STO) or the lead zirconate titanate (PbZrTiO 3 , PZT). These insulators have many remarkable electrical characteristics such as a very high k-value or piezoelectric, ferroelectric properties. k-value can reach the range from 100 to thousands at low frequencies thanks to ‘perovskite’ crystalline structure [10–13], which becomes very interesting to achieve high-density MIM capacitors [14]. Numerous investigations were reported on these materials, but few of them develop their high frequency (HF) electrical IET Microw. Antennas Propag., 2008, Vol. 2, No. 8, pp. 781–788 781 doi: 10.1049/iet-map:20070344 & The Institution of Engineering and Technology 2008 www.ietdl.org