Low-temperature growth and orientational control in RuO 2 thin films by metal-organic chemical vapor deposition

Abstract

For growth temperatures in the range of 275°C to 425°C, highly conductive RuO 2 thin films with either (110)- or (101)-textured orientations have been grown by metal-organic chemical vapor deposition (MOCVD) on both SiO 2/Si(001) and Pt/Ti/SiO 2/Si(001) substrates. Both the growth temperature and growth rate were used to control the type and degree of orientational texture of the RuO 2 films. In the upper part of this growth temperature range (∼ 350°C) and at a low growth rate (< 3.0 nm/min.), the RuO 2 films favored a (110)-textured orientation. In contrast, at the lower part of this growth temperature range (∼ 300°C) and at a high growth rate (> 3.0 nm/min.), the RuO 2 films favored a (101)-textured orientation. In contrast, higher growth temperatures (> 425°C) always produced randomly-oriented polycrystalline films. For either of these low-temperature growth processes, the films produced were crack-free, well-adhered to the substrates, and had smooth, specular surfaces. Atomic force microscopy showed that the films had a dense microstructure with an average grain size of 50–80 nm and a rms. surface roughness of ∼ 3–10 nm. Four-probe electrical transport measurements showed that the films were highly conductive with resistivities of 34–40 μΩ-cm (at 25°C).