Enhanced dielectric properties of Zr−Sn−Ti oxynitride thin films
Zr0.26Sn0.23Ti0.51OxOy (ZSTON) and Zr0.26Sn0.23Ti0.51O2σ (ZSTO) films have been prepared on Pt coated silicon substrates by pulsed laser deposition technique using a Zr−Sn−Ti oxide target at a substrate temperature of 650°C in N2 and O2 ambient, respectively. TEM observation showed that both kinds of films are amorphous. XPS analysis showed that the N/O ratio in ZSTON is 0.08/0.92. With the help of a comparative study of the dielectric properties of ZSTON and ZSTO films, it has been found that incorporation of nitrogen can increase the dielectric coefficient and decrease the dielectric loss of the multicomponent oxide films remarkably. Optical transmittance measurements showed that incorporation of nitrogen can slightly decrease the width of the bandgap and increase the refractive index of the films. It is proposed that amorphous Zr−Sn−Ti oxynitride stable at 650°C is a potential dielectric material for DRAM applications.