AVS 49th International Symposium
    Plasma Science Monday Sessions
       Session PS1-MoA

Paper PS1-MoA7
Ion-enhanced Chemical Etching of ZrO@sub 2@ in a Chlorine Discharge

Monday, November 4, 2002, 4:00 pm, Room C-103

Session: Dielectric Etch I
Presenter: L. Sha, University of California, Los Angeles
Authors: L. Sha, University of California, Los Angeles
J.P. Chang, University of California, Los Angeles
Correspondent: Click to Email
Novel plasma etching chemistries are needed to pattern high dielectric constant materials, such as ZrO@sub 2@, to enable their integration in sub-0.13 µm complementary metal oxide semiconductor (CMOS) devices. In the work, we aim to study the reaction kinetics of etching ZrO@sub 2@ in chlorine chemistry in an Electron Cyclotron Resonance (ECR) high-density plasma reactor. The gas phase species, including the reactants (Cl@sub 2@, Cl@sub 2@@super +@, Cl, Cl@super +@, Cl@super -@, …) and the etching products (zirconium chlorides and chlorine oxides), were identified with optical emission spectroscopy (OES) and quadrupole mass spectroscopy (QMS). The etch rate was determined to scale linearly with the square root of ion energy in the higher ion energy regime (E@sub ion@ > 60 eV), indicating that it is limited by the momentum transfer to the etched film. At low ion energies, the etch rate was quite constant, likely due to reactive sputtering of the metal oxides. The etching products were found to be predominantly ZrCl@sub 3@ (>70%) at low ion energies. However, ZrCl@sub 4@ became dominant at much higher ion energies. This is likely due to the enhanced surface chlorination under higher ion energy impact. This is in good agreement with X-ray photoelectron spectroscopy (XPS) measurements, which revealed increased surface chlorine content in the film etched at higher ion energy. The concentrations of the gas phase species will be quantified with actinometry and QMS, as a function of the chlorine pressure, ion energy, and the microwave power. The etching mechanism will be proposed and the reaction rate coefficients will be calculated based on a CSTR model. CHEMKIN will be used to simulate the etching process and the results will be compared with the experimental measurement. Finally, BCl@sub 3@ will be introduced to assess its effects on the etching selectivity of ZrO@sub 2@ to Si.