AVS 49th International Symposium
    Dielectrics Wednesday Sessions
       Session DI+EL-WeP

Paper DI+EL-WeP13
Etching Characteristics of Bi@sub 4-x@Eu@sub x@Ti@sub 3@O@sub 12@ Thin Films Using Inductively Coupled Plasma

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

Session: Poster Session
Presenter: C.I. Kim, 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
In recent years, some Bi-layered perovskite oxide such as SrBi@sub 2@Ta@sub 2@O@sub 9@ (SBT) and Bi@sub 4-x@La@sub x@Ti@sub 3@O@sub 12@ (BLT) have been intensively studied for use in FRAMs because of its low leakage current, low coercive field, and fatigue-free with simple Pt electrode. The fatigue-free behavior of SBT and BLT thin film was due to the charge compensating effect of Bi@sub 2@O@sub 2@ layers resulting in the reduction of space charge and from domain wall unpinning that happens at least as rapidly as domain pinning. However, SBT and BLT thin films have a disadvantage of low remanent polarization for the high-density integration of FRAMs. From the viewpoint of the general formula of Aurivillius compounds, radii of Europium ion (0.95 Å), similar to Bi ion (0.93 Å) in the Bi@sub 4@Ti@sub 3@O@sub 12@(BIT), occupies the A site in the perovskite unit BIT. The europium-substituted BIT(BET) thin films resulted in a large 2Pr, whose value (60.99µmC/cm@super 2@) is much larger than that of Sm-modified BIT thin film (2Pr = BSmT: 49µmC/cm@super 2@) and BLT thin film (2Pr = 27µmC/cm@super 2@) at an applied voltage of 10V. For this advantage, BET thin films have emerged as new ferroelectric materials. However, there is no report on etching BET thin films. Inductively coupled plasma source was used for etching BET because of its high plasma density, low process pressure and easy control bias power. BET thin films were etched with using CF@sub 4@/Ar plasma. The experiments were carried out with measuring etch rates and selectivities as a function of gas mixing ratio, rf power, dc bias voltage. The chemical states on the etched surface were investigated with x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to investigate the surface morphology of BET thin films exposed in plasma and etching profile.