Electrical and structural properties of ultrathin polycrystalline and epitaxial TiN films grown by reactive dc magnetron
- PDF / 1,695,467 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 30 Downloads / 229 Views
1156-D03-05
Electrical and structural properties of ultrathin polycrystalline and epitaxial TiN films grown by reactive dc magnetron sputtering
F. Magnus1, A. S. Ingason1, S. Olafsson1, and J. T. Gudmundsson1,2 1
Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik, Iceland.
2
Department of Electrical and Computer Engineering, University of Iceland, Hjardarhaga 2-6, IS-107 Reykjavik, Iceland.
ABSTRACT Ultrathin TiN films were grown by reactive dc magnetron sputtering on amorphous SiO2 substrates and single-crystalline MgO substrates at 600°C. The resistance of the films was monitored in-situ during growth to determine the coalescence and continuity thicknesses. TiN films grown on SiO2 are polycrystalline and have coalescence and continuity thicknesses of 8 Å and 19 Å, respectively. TiN films grow epitaxially on the MgO substrates and the coalescence thickness is 2 Å and the thickness where the film becomes continuous cannot be resolved from the coalescence thickness. X-ray reflection measurements indicate a significantly higher density and lower roughness of the epitaxial TiN films. INTRODUCTION TiN thin films are widely used as adhesion layers and diffusion barriers in Cu interconnects in modern microelectronics [1]. This is in part due to the excellent thermal stability and low bulk electrical resistivity of TiN. Recently, TiN has been proposed as a direct-metal-gate material for metal-oxide-semiconductor devices [2]. For the above applications it is desirable to reduce the thickness of the TiN film as much as possible but the film must remain continuous. In addition, it is important to maintain the low resistivity even in the ultrathin limit. Furthermore, highly textured or epitaxial thin MgO films have received much interest lately due to their applications in magnetic tunnel junctions [3]. Epitaxial MgO films could also be a possible candidate for an intermediate-to-high-κ gate dielectric [4]. It is therefore important to find a suitable gate-metal for the MgO gate dielectric. Here we compare the electrical and structural properties of ultrathin TiN films grown on SiO2 substrates and single-crystalline MgO[200] substrates by reactive dc magnetron sputtering. The electrical resistance of the films was monitored during growth in-situ to determine the coalescence thickness and the thickness at which the films become continuous. In addition, we examine crystallinity, density and roughness of the films ex-situ with X-ray diffraction (XRD) and reflection (XRR) measurements.
EXPERIMENT The TiN thin films were grown in a custom built magnetron sputtering chamber [5] with a base pressure of 4 × 10-6 Pa for 30 minutes. The sputtering gas was argon of 99.999% purity mixed with nitrogen gas of 99.999% purity. The argon flow rate was 40 sccm and the nitrogen flow rate 2 sccm to give a pressure of 0.4 Pa. The Ti target was 50 mm in diameter and of 99.99% purity. The applied power was set to 100 W. The substrates used were thermally oxidized Si[001] with an oxide thickness of 500 nm and single-crystal
Data Loading...
