AVS 52nd International Symposium
    Plasma Science and Technology Wednesday Sessions
       Session PS+TF-WeM

Paper PS+TF-WeM11
Plasma-Enhanced Atomic Layer Deposition for Compositionally Controlled Metal Oxide Thin Films

Wednesday, November 2, 2005, 11:40 am, Room 302

Session: Plasma Enhanced CVD and ALD
Presenter: K.M. Cross, University of California, Los Angeles
Authors: R.M. Martin, University of California, Los Angeles
K.M. Cross, University of California, Los Angeles
J.P. Chang, University of California, Los Angeles
Correspondent: Click to Email
The need to replace SiO@sub 2@ by a higher dielectric constant material in fabricating smaller and faster metal-oxide-semiconductor (MOS) transistors is well recognized by the National Technology Roadmap for Semiconductors. Atomic layer deposition emerges as a viable chemical processing technique to enable the deposition of ultra-thin and highly conformal thin films, and the use of plasma allows greater flexibility in designing doped or alloyed thin films with controlled compostition. In this work, we discuss the atomic layer deposition of HfO@sub 2@ and Hf@sub 1-x@Si@sub x@O@sub y@ using an alternating, cyclical sequence of hafnium terta-tert butoxide and tetra ethyl ortho silicate as the chemical precursors and oxygen radicals generated from an oxygen plasma as the oxidant. Optical emission spectroscopy (OES) was used to identify and quantify the gas phase atomic species. The thicknesses of the films scaled linearly with the number of deposition cycles as determined by both ellipsometry and x-ray photoelectron spectroscopy (XPS) measurements. Thin film composition of Hf@sub 1-x@Si@sub x@O@sub y@ can be varied and controlled by the chemical sequences, as verified by XPS compositional analysis. Atomic force microscopy (AFM) was used to determine surface roughness of the deposited films as a function of the deposition chemistry sequence and film thickness. MOS transistors were fabricated with the PEALD deposited films and capacitance-voltage (C-V) and current voltage (I-V) measurements showed that the PEALD HfO@sub 2@ films had a dielectric constant of 25 and an equivalent oxide thickness of 12.5-15 Å. Device results of Hf@sub 1-x@Si@sub x@O@sub y@ will be discussed as a function of the Si concentration and the resulting interfacial composition.