AVS 45th International Symposium
    Surface Science Division Wednesday Sessions
       Session SS2-WeA

Paper SS2-WeA1
Photochemical Routes to Group IV Deposition

Wednesday, November 4, 1998, 2:00 pm, Room 309

Session: Photochemistry and Deposition
Presenter: G.J. Batinica, University of California, San Diego
Authors: G.J. Batinica, University of California, San Diego
J.L. Stepnowski, University of California, San Diego
J.E. Crowell, University of California, San Diego
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The fabrication of high-speed electronic devices requires the controlled epitaxial deposition of Si and SiGe thin films. We have explored both thermal and photochemical routes to Si and Ge deposition using disilane (Si@sub 2@H@sub 6@) and digermane (Ge@sub 2@H@sub 6@) as model hydride deposition sources. We have also compared the thermal and photochemical reactivity of Si(100) versus that of Si(111). The deposition reactions have been studied using multiple internal reflection infrared spectroscopy (MIRIRS), temperature programmed desorption (TPD), and Auger electron spectroscopy (AES). Hydrogen and silane (SiH@sub 4@) desorption yields were used to determine the reactivity of disilane on the Si surfaces with and without UV irradiation. Hydrogen and germane desorption yields and relative Ge/Si AES signals were used to determine the reactivity of digermane. UV irradiation during or after dosing of the Si crystal surfaces at 110K greatly enhanced the reactivity of disilane and digermane compared to similar exposures without UV irradiation. Comparison of the reactivity of disilane with Si(100) versus Si(111) show that Si(111) is thermally less reactive than the Si(100) surface. However, both surfaces show similar photo-reactivity to disilane. The photo-induced mechanism of disilane and digermane reactions has been studied using clean, partially deuterated and fully deuterated Si(111) and Si(100) surfaces. Thermally, the reactivity is controlled by the surface dangling bonds; whereas the photo-induced deposition chemistry appears to primarily involve insertion by the photo-generated diradicals, silylene and germylene. The implication of our results on deposition methodologies will be discussed.