AL3O3 THIN-FILM GROWTH ON SI(100) USING BINARY REACTION SEQUENCE CHEMISTRY

Al2O3 films with precisely controlled thicknesses and excellent confor mality were grown on Si(100) at low temperatures of 350-650 K using se quential surface chemical reactions. This controlled deposition was ac hieved by separating a binary reaction for Al2O3 chemical vapor deposi tion (2Al(CH3)(3) + 3H(2)O --> Al2O3 + 6CH(4)) into two half-reactions : (A) AlOH + Al(CH3)(3) --> AlOAl(CH3)(2)* + CH4 (B) AlCH3* + H2O --> AlOH + CH4 In the above reactions, the trimethylaluminum [Al(CH3)(3) ] (TMA) and H2O reactants were employed alternately in an ABAB... bina ry reaction sequence where the asterisks designate the surface species . At the optimal reaction conditions, a growth rate of 1.1 Angstrom pe r AB cycle was measured on the Si (100) substrate using ellipsometry. These Al2O3 films had an index of refraction of n = 1.65 and a corresp onding density of rho = 3.50 g cm(-3). Additional ellipsometric measur ements revealed that the Al2O3 deposition rate per AB cycle decreased at substrate temperatures >450 K. The decrease in the growth rate clos ely matched the thermal stability of the AlOH and AlCH3* surface spec ies previously measured with FTIR spectroscopy. This correlation suppo rts a reaction mechanism based on self-limiting surface chemistry. Ato mic force microscope images revealed that the deposited Al2O3 films we re exceptionally flat with a surface roughness of only +/-3 Angstrom ( rms) after 500 AB cycles and the deposition of a film thickness of sim ilar to 560 Angstrom. The power spectra of the surface topography meas ured by AFM also demonstrated that the surface roughness was nearly id entical for the initial Si(100) substrate and the deposited Al2O3 film s after 20-500 AB reaction cycles.