Sensors and Actuators A 128 (2006) 376–386 SiC cantilever resonators with electrothermal actuation Liudi Jiang a,∗ , R. Cheung a , J. Hedley b , M. Hassan c , A.J. Harris c , J.S. Burdess b , M. Mehregany d , C.A. Zorman d a School of Engineering and Electronics, Scottish Microelectronics Centre, The University of Edinburgh, King’s Buildings, West Mains Road, Edinburgh EH9 3JF, UK b School of Mechanical and Systems Engineering, University of Newcastle Upon Tyne, Newcastle NE1 7RU, UK c School of Electrical, Electronics and Computer Engineering, University of Newcastle Upon Tyne, Newcastle NE1 7RU, UK d Department of Electrical Engineering and Computer Science, Case Western Reserve University, Cleveland, OH 44106, USA Received 4 October 2005; received in revised form 23 January 2006; accepted 31 January 2006 Available online 10 March 2006 Abstract Cubic SiC cantilever resonators designed for electrothermal actuation are presented. Metal electrodes with both open circuit and short circuit designs have been deposited and patterned on top of the 3C–SiC cantilevers. Pt electrodes on single crystal 3C–SiC cantilevers and NiCr electrodes on poly-crystalline 3C–SiC cantilevers have both been fabricated and tested in order to investigate the material property effect on the performance of the devices. An analytical model has been developed to understand the electrical power distribution in the cantilevers for the different material systems as well as the different metal terminations. Electrothermal actuation of resonance has been successfully achieved in all the fabricated cantilevers. The dynamic performance of the cantilever resonators has been systematically studied including resonance frequencies, amplitude response with voltage and actuation efficiencies. During the discussion of these results, the mechanism of the electrothermal actuation in these devices has been identified which allows actuation frequencies up to 100 MHz to be possible. © 2006 Elsevier B.V. All rights reserved. Keywords: Electrothermal actuation; SiC; Cantilever; Resonators 1. Introduction Many methods for actuation of microelectromechanical system (MEMS) structures have been demonstrated, these include electrostatic, thermal, piezoelectric and electromag- netic. Among these methods, capacitive actuation has most commonly been used because of its low power consumption and short actuation times. However, capacitive actuation requires two electrodes separated by an insulator. One electrode is fixed and the other is attached or formed from the structure to be actu- ated. This requires the formation of a layered structure which in some cases can unnecessarily complicate the design and fab- rication process and demands that the insulator be completely free of electrical shorts. A far simpler alternative is electrother- mal actuation which only requires an electrical conductor to be deposited onto the surface of the structure to be actuated and ∗ Corresponding author. Tel.: +44 023 8059 8748; fax: +44 023 8059 3016. E-mail address: ldjiang@soton.ac.uk (L. Jiang). the electrical power to be used to heat and hence mechanically strain the structure. Furthermore, capacitive actuation is often associated with a large closing gap in order to achieve high isolation and avoid pull-in [1,2] and stiction problems, which results in large actuation voltages [3]. In contrast, electrother- mal actuation can be operated at relatively low voltages and is therefore compatible with standard IC voltage levels and it can also result in larger displacements and higher contact force with more compact structures [4]. These advantages of elec- trothermal actuation are particularly attractive for the actuation of MEMS switches [5], micromirrors [6], microtweezers [7] and AFM tips [8]. In addition, like capacitive actuation, electrother- mal actuation can also function as a frequency mixer/filter due to the induced mechanical force being a function of the applied voltage squared [9]. Silicon Carbide (SiC) is a good candidate for microsensor and microactuator applications in harsh environments including locations of high temperature and abrasive and corrosive media. The progress on 3C–SiC deposition onto various large area sub- strates [10] and the development of surface micromachining 0924-4247/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.sna.2006.01.045