AVS 49th International Symposium
    Plasma Science Thursday Sessions
       Session PS+TF-ThM

Paper PS+TF-ThM1
The Correlations between Gas Phase Chemistry, Material Properties, and Device Characteristics of PECVD ZrO@sub 2@ Thin Films

Thursday, November 7, 2002, 8:20 am, Room C-103

Session: Plasma Enhanced Deposition
Presenter: B. Cho, University of California, Los Angeles
Authors: B. Cho, University of California, Los Angeles
J.P. Chang, University of California, Los Angeles
Correspondent: Click to Email
We investigated ZrO@sub 2@ as a replacement dielectric film of SiO2 for dynamic random access memory (DRAM) capacitor. We used ECR-PECVD process to deposit ZrO@sub 2@ films on p-Si (100) wafers with zirconium tetra-tert-butoxide (ZTB; Zr(OC@sub 4@H@sub 9@)@sub 4@) as an organometallic precursor, Ar as a carrier of the precursor vapor, and O@sub 2@ as an oxidant. Optical emission spectroscopy (OES), Langmuir probe, and quadrupole mass spectrometry (QMS) were used to characterize the plasma. Using QMS, we identified all oxidation states of Zr and found the compositional abundance shifted from Zr metal and monoxide to Zr dioxide and trioxide with the increase in O@sub 2@ /Ar flow rate ratio (O@sub 2@ /Ar). Based on the results, we proposed the oxidation and the decomposition reaction mechanisms of ZTB precursors. The as-deposited films obtained without any heating had monoclinic and tetragonal polycrystalline phases based on the grazing incidence x-ray diffraction analysis. High resolution transmission electron microscopy showed that the polycrystalline phase of ZrO@sub 2@ was interspersed with amorphous phase and that interfacial layer was formed between the ZrO@sub 2@ and the substrate Si. Static secondary ion mass spectrometry showed that Zr concentration was uniform across the bulk ZrO@sub 2@ film from both oxygen-rich and oxygen-deficient conditions but Si/Zr ratio was much higher in the interfacial layer obtained in the oxygen-rich condition. This suggested that the oxygen-rich condition resulted in more SiO@sub 2@-like interfacial layer. X-ray photoelectron spectroscopy (XPS) showed that stoichiometric ZrO2 film was obtained while an interfacial layer containing Si-O bond was formed even without any O@sub 2@ addition to the plasma.