AVS 47th International Symposium
    Thin Films Monday Sessions
       Session TF-MoM

Paper TF-MoM4
Thermal Stability of Si and C Atomic Layers Formed on Ge(100) in Silane and Methylsilane Reactions

Monday, October 2, 2000, 9:20 am, Room 203

Session: Atomic Layer Chemical Vapor Deposition I
Presenter: M. Fujiu, Tohoku University, Japan
Authors: M. Fujiu, Tohoku University, Japan
M. Sakuraba, Tohoku University, Japan
T. Matsuura, Tohoku University, Japan
J. Murota, Tohoku University, Japan
Correspondent: Click to Email
In order to realize an atomic layer superlattice of group IV semiconductors, self-limited control of adsorption and reaction of reactant gases and suppression of the mutual diffusion at the hetero interfaces are essential. In this work, thermal stability of Si and C atomic layers formed on Ge(100) in SiH@sub 4@ and CH@sub 3@SiH@sub 3@ reactions was investigated using XPS by an ultraclean low-pressure CVD system. With CH@sub 3@SiH@sub 3@ reaction on Ge(100) at 18Pa, the concentration of Si deposited on Ge(100) was nearly the same as that of C during the reaction at the temperature of 550@super o@C or lower. Especially at 450@super o@C, single atomic layers of Si and C were formed self-limitedly on Ge(100). When the single atomic layers were subsequently annealed for 60 min at 600@super o@C, the C atom concentration decreased from the single atomic layer to about half of the atomic layer, although the Si atom concentration hardly changed. The result suggests that the Si-C bond is gradually broken by annealing at 600@super o@C, and the C atom desorbs. On the other hand, with SiH@sub 4@ exposure on Ge(100) at 120Pa, the deposited Si concentration saturated to that of the single atomic layer at 300@super o@C. After formation of the Si single atomic layer on Ge(100) followed by further annealing for 60 min at 500@super o@C and subsequent SiH@sub 4@ exposure for 30 min at 300@super o@C, the deposited Si concentration increased and reached to 120% of the Si single atomic layer. It is suggested that atomic order mixing occurs even at 500@super o@C at the interface between the Si atomic layer and the Ge substrate, and the segregated Ge atom enhances the further SiH@sub 4@ reaction on the surface. The above results reveal that the atomic order mixing is greatly suppressed by the existence of C atoms on the surface. The dependence of the growth and annealing temperatures on the thermal stability of Si and C atomic layers on Ge(100) will be presented.