<title>Novel MOCVD processes for nanoscale dielectric and ferroelectric thin films</title>

Abstract

Nanoscale oxide thin films such as Ba1-xSrxTiO3 (BST), PbZr1-xTixO3 (PZT) and SrBi2(Ta1-xNbx)2O9 (SBTN) that have high dielectric constant and excellent ferroelectric properties have been receiving greatly increased attention, specially for high density memories in next generation integrated circuits. However, most MOCVD precursors for dielectric and ferroelectric film growth have a very low vaporization pressure and poor thermal stability at elevated temperatures. Moreover, when the film thickness is decreased, the apparent bulk-like properties of thin films tend to worsen due to the increased influence of the interface. In order to solve the problems, novel MOCVD techniques including the development of a new liquid delivery, plasma (ECR or RF) enhanced deposition, TurboDisc technology and two step process were developed. The thickness uniformity, composition uniformity and dielectric and ferroelectric property uniformity of BST, PZT and SBT thin films on 6' Si and Pt wafers are also investigated. Experimental results showed that the new liquid delivery system can improve process reproducibility and increase deposition rates, and the growth reactor with high speed rotation system can deposit homogeneous ultra-thin films on large size substrates, and plasma enhanced MOCVD can reduce the deposition temperature and increase the deposition rate to decrease growth temperature without compromising the quality of the material, and the two step processes can be used to improve interface mismatch between film and substrate. Therefore, high quality dielectric and ferroelectric thin films with nanoscale thickness can be obtained.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.