AVS 49th International Symposium
    Plasma Science Wednesday Sessions
       Session PS+TF-WeP

Paper PS+TF-WeP15
Plasma Damage Reduction in PZT Thin Films Etched by Inductively Coupled Plasma

Wednesday, November 6, 2002, 11:00 am, Room Exhibit Hall B2

Session: Plasma Etching & Deposition
Presenter: K.T. Lim, Chung-Ang University, Korea
Authors: K.T. Lim, Chung-Ang University, Korea
D.P. Kim, Chung-Ang University, Korea
K.T. Kim, Chung-Ang University, Korea
C.I. Kim, Chung-Ang University, Korea
Correspondent: Click to Email
Ferroelctric lead zirconate titanate (Pb(Zr,Ti)O@sub 3@) thin films have been known for their applications in memory devices such as nonvolatile ferroelecric random access memory (FRAM) because of their high dielectric constants and bistable polarization. It is expected that PZT will improve the limitations in storage density encountered in conventional Si memory technology. During the dry etching, the defects, such as physical damage and chemical residue contamination and decomposition, will change the near surface region of the material that is exposed to the plasma and degrade ferroelecric and electrical properties. In this study, PZT thin films were prepared on Pt/Ti/SiO@sub 2@/Si substrates by sol-gel processes. Pt top electrodes were deposited on PZT thin films by using rf magnetron sputtering. SiO@sub 2@ was deposited on Pt top electrodes. SiO@sub 2@ layer was etched in CF@sub 4@/Ar inductively coupled plasma with PR mask. We continued etching Pt/PZT/Pt layer without removing PR and SiO@sub 2@ patterns. PZT thin films were etched with Ar/Cl@sub 2@ inductively coupled plasma. The etch rate is observed by various parameters. We also observed the effect of etching damage in PZT thin films during etching in Cl@sub 2@/Ar plasma. The ferroelectric and electrical properties were measured with a precision workstation. We obtained stable value of remanent polarization and good fatigue resistance for PZT with SiO@sub 2@ mask as compared with Pt dot, which was used as physical mask during etching process. The structural damages to the near surface of PZT are evaluated by transmission electron microscope (TEM) and x-ray diffraction (XRD). The chemical deformation of etched surface was surveyed x-ray photoelectron spectroscopy (XPS), electron probe micro analyzer (EPMA), auger electron spectroscopy (AES) and TEM-EDS.