Titanium-dioxide film formation using gas cluster ion beam assisted deposition technique O. Nakatsu a,b, * ,J.Matsuo b ,K.Omoto b ,T.Seki b ,G.Takaoka b ,I.Yamada c a Semiconductor Equipment Division, Shimadzu Corporation, 380-1, Horiyamashita, Hadano-city, Kanagawa 259-1304, Japan b Ion Beam Engineering Experimental Laboratory, Kyoto University, Yoshidahonmachi, Sakyo-ku, Kyoto 606-8317, Japan c Laboratory of Advanced Science and Technology, Himeji Institute of Technology, 1-2, 3 chome, Kouto, Kamigori-cho, Ako-gun, Hyogo 678-1205, Japan Abstract Gas cluster ion beam (GCIB) assisted deposition technique has been applied to form titanium-dioxide films. When oxygen cluster ions collide on solid surfaces, oxygen molecules in the clusters enhance oxidation due to high density energy deposition. Metal titanium pellets were used as source material for EB evaporation, because evaporation with metalpelletsismuchstablethanthatofoxidepellets.Filmsweredepositedonsapphire(0001)substrateswithvarious conditions.CharacteristicsofthefilmswereexaminedbyuseofXRD,RBSandAFM.Whenfilmwasdepositedwith theaccelerationvoltageof7kVat473K,thewellc-orientedrutileTiO 2 filmwasformedwithaverageroughnessof0.4 nm.WithoutassistanceofGCIBroughamorphousfilmwasformedinanatmosphereofoxygen.Verysmoothsurface films with good crystallinity were formed by GCIB assisted deposition technique. Ó 2003 Elsevier Science B.V. All rights reserved. PACS: 81.15.Jj; 68.55.Jk; 77.84.Bw Keywords: Cluster; Ion; Assist; Deposition; Titanium dioxide; Titania 1.Introduction Gas cluster ion beam process has been devel- oped at Kyoto University [1]. Subsequently this technique was applied to deposition processes, namely gas cluster ion beam assisted deposition. Formation of diamond like carbon (DLC) film and tin-doped indium-oxide (ITO) film using GCIB cluster beam was reported previously [2,3]. In this paper titanium dioxide (TiO 2 ) film deposi- tion is reported. Titanium dioxide (TiO 2 ) has nu- merous crystalline structures, such as, rutile, anatase and brookite and so on. It is known that anatase and brookite structures transforms to ru- tile structure at a temperatures exceeding 1073 K. Because of large refractive index of TiO 2 , it has being applied to optical interference films. TiO 2 film deposition was reported using various depo- sition techniques [4–8]. During gas cluster ion beam assisted deposition, gas cluster ion collides with the film deposited at the substrate, where * Corresponding author. Address: Ion Beam Engineering Experimental Laboratory, Kyoto University, Yoshidahon- machi, Sakyo-ku, Kyoto 606-8317, Japan. Tel.: +81-75-753- 4994; fax: +81-75-751-6774. E-mail address: nakatsu@nishiki.kuee.kyoto-u.ac.jp (O. Nakatsu). 0168-583X/03/$ - see front matter Ó 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0168-583X(03)00880-2 Nuclear Instruments and Methods in Physics Research B 206 (2003) 866–869 www.elsevier.com/locate/nimb