METHOD FOR DEPOSITION OF FERROELECTRIC THIN FILMS

摘要

A method is described for the nucleation controlled deposition of ferroelectric thin films by chemical vapor deposition in a novel processing sequence wherein a higher density of bismuth nucleation sites is achieved either by the use of a substrate member which has been treated in a manner to yield a controllably and reproducible rough surface on which SBT films with excellent properties may be produced or by using a chemically modified substrate surface upon which surface chemical properties are modified. Typical techniques for achieving surface roughening include reactive ion etching, inert ion milling and chemical mechanical polishing, each of which may be used to delineate patterned bottom electrodes. The chemical properties of the substrate may be modified by alloy deposition, deposition of seed layers which are then partially or completely in-diffused ion implantation with or without heat treatment and changing the chemistry of the surface by a pre-exposure to chemical agents prior to deposition. The resultant oxide ferroelectric thin films are suitable for use in capacitors, memory devices and the like.