ELSEVIER Thin Solid Films 300 (1997) 272-277 HHI$ The effect of rapid thermal annealing on structural and electrical properties of TiB 2 thin films B. Todorovid *, T. Jokid, Z. Rako~evid, Z. Markovid, B. Gakovid, T. Nenadovid Atomic Physics Laboratory, Institute of Nuclear Sciences "Vin~a", P.O.B. 522, i100I Belgrade, Yugoslavia Received7 June 1996; accepted9 October 1996 Abstract This work reports on the effect of post-deposition rapid thermal annealing on the structural and electrical properties of deposited "riB 2 thin films. Tlie TiB 2 thin films, thicknesses from 9 to 450 nm, were deposited by e-beam evaporation on high resistivity and thermally oxidized silicon wafers. The resistivity of as-deposited films varied from 1820 ~fl cm for the thinnest film to 267 pi~ cm for thicknesses greater than 100 nm. In the thickness range from 100 to 450 nm, the resistivity of TiB a films has a constant value of 267 bf~ cm. A rapid thermal annealing (RTA) technique has been used to reduce the resistivity of deposited films. During vacuum annealing at 7 X t0 .3 Pa, the film resistivity decreases from 267 ~f~ cm at 200 °C to 16 ~f~ cm at 1200 °C. Heating cycles during RTA were a sequence of 10 s. According to scanning tunneling microscopy analysis, the decrease in resistivity may be attributed to a grain growth through polycrystalline recrystallization, as well as to an increase in film density. The grain size and mean surface roughness of annealed films increase with annealing temperature. At the same time, the conductivity of the annealed samples increases linearly with grain size. The obtained results show that RTA technique has a great potential for low resistivity TiB 2 formation. © 1997 Published by Elsevier Science S.A. Keywords: Annealing; Electrical propertiesand measurements;Evaporation;Scanning tunnelling microscopy 1. Introduction Transition metal silicides are widely used as conductors in silicon integrated circuits (IC), because they fulfil the main requirements for application in them [1]. The increas- ing demands of the IC performance have imposed the necessity of development of new materials and processes for metaltization and interconnects. The transition metal borides belong to the group of such new materials because of their high electrical conductivity, higher than that of pure metals, high thermal and chemical stability and possi- ble microelectronics applications [2,3]. Furthermore, transi- tion metal borides are inert with respect to copper, silver and gold. So, they are useful as diffusion barriers [4,5]. It is an aim of this paper to show how deposition parameters and a subsequent rapid thermal annealing (RTA) process determine the resulting TiB 2 film properties -- electrical and structural. A rapid thermal annealing tech- nique offers a number of advantages over the more con- Corresponding author. ventional furnace heating, such as the ability to perform isothermal and short heating cycles without creating tem- perature gradients within the heated sample and to provide an accurate control of the time-temperature heating cycles [61. Resistivity measurements have received wide attention from experimental and theoretical side in order to gain insight into the electrical and structural properties of thin films. The resistivity of boride thin films is much greater than that of bulk specimens. Orain boundaries, defects and trapped impurities are responsible for high resistivity val- ues in thin films [7]. The thinner the film, the more marked is the effect. The resistivity of single crystal TiB 2 sample is 6.6 + 0.2 txg~ cm and independent of the orientation of the crystal. The same parameter for polycrystalline bulk TiB 2 having a density greater than 90% lies between 9 and 15 ~f~ cm [8]. These values are lower than that of other potential barrier materials such as silicides or nitrides. Thus, TiB 2 appears to be an interesting potential candidate for ULSI metallization applications [9]. The deposition and annealing parameters can influence the volume and surface microstructure of a deposited thin 0040-6090/97/$17,00 © 1997 Published by ElsevierScience S.A. All rights reserved. PII 80040-6090(96)09458-8