Fabrication and dielectric properties of SCT thin film by RF sputtering method

Abstract

The (Sro 9C~.l)Ti03(SCT) thin films were deposited on Pt-coated electrode(Pt/TiN/Si02/Si) using RF magnetron sputtering method. The composition of SCT thin film were closed to stoichiometry(l.081 in N B ratio). The optimum annealing temperature of SCT thin f i l m was 600['c]. The dielectric constant depending on the annealing temperature was shown to be the great 146 at 6OO['C]. The temperature coefficients of capacitance exhibit very stable values below *4[%] in the temperature range of -SO-9O["c]. The temperature properties of the dielectric loss have a stable value within 0.02. The drastic decrease of dielectric constant and increase of dielectric loss in SCT thin films is observed above 2OO[kHz]. LNTRODUCTIONFor a long time, studies on dielectrics have been steadily conducted by number of researcher: nevertheless, the studies have been focused on a thin film rather than the bulk form due to miniaturization and integration of electronic apparatus. This dielectric thin film, which was made by using various process technologies, can be possibly integrated on a semiconductor element, and prospects of developing a new electronic element, Particulariy, these studies have been actively conducted on application of memory element using the dielectric thin film. Due to a rapid development of semiconductor technologies and electronic ceramics, the smaller and the lighter devices are able to be manufactured. In view of the low dielectric constant and the physical thickness limit of conventional S i 0 2 dielectric thin films, high dielectric constant materials are being evaluated for applications in DRAMS. Ferroelectrics and related dielectrics have also been suggested for DRAM applications. For DRAM applications, ferroelectric properties such as polarization hysteresis are not essential, only a high dielectric constant with good insulating properties is required. Strontium titanate is an attractive material for very large scale intergrated(VLS1) DRAMS because of its high charge storage capacity, good insulating behavior, small temperature coefficient of capacitance, and paraelectricity in the operating temperature range of these devices.[l,2] Additionally, due to miniaturization and integration of electronic apparatus, studies have focused on the thin film form rather than the bulk form. As a method for as-deposition of the thin film, various methods, such as Sol-Gel, MOCVD, and sputtering, have been continuously used on trial. Among these methods, the sputtering method is mostly used for deposition of oxide thin film, like the vacuum deposition method. Pennebaker reported on RF sputtered strontium titanate, where the films were deposited on sapphire discs coated with various metal films.[3] However, studies of dielectric properties of (Sr,.,Ca,)TiO, thin films on a Si substrate are scarcely any. Sputtering techniques have recently received considerable attention, because of the inherent advantages of sputtering as a deposition method.Condensation energy is high in the formation of thin film. And it is able to manufactu...