Selective MOCVD of titanium oxide and zirconium oxide thin films ...

ARTICLE IN PRESSB.-C. Kang et al. / Journal of Physics and Chemistry of Solids 69 (2008) 128–132 131OTS SAMs area and ZrO 2 deposited area is clear.However, as the deposition time was increased up to 4 h,the boundary became very unclear. It means the ZrO 2 wasable to deposit both hydrophilic area and hydrophobicarea. We can suggest that the terminal group of OTS wasoxidized and changed its character from hydrophobic tohydrophilic or removed from the substrate surface becausethe high deposition temperature and long deposition time[25]. The morphology of ZrO 2 thin film grown on Si(1 0 0)substrate was denser and smoother than that of ZrO 2 thinfilm grown on OTS SAMs surface.XPS survey spectrum analysis was carried out of the asdepositedZrO 2 film grown on Si(1 0 0) substrate at 450 1C(not shown here). The strong Zr 3d and O 1s peaks wereclearly indicated. However, C 1s peak clearly appearedaround 300 eV binding energy, we can guess that thecarbon comes from the precursor during depositions and/or surface contamination from the air. Also, the O 1s andZr 3d high-resolution XPS spectra were performed(not shown here). In the case of O 1s , there are twooxidation states attributed to O 2 and OH species at thebinding energy of about 532 and 530 eV. We can ensurethat the OH peak is just a surface contamination peakprobably originated from H 2 O in the air. The Zr 3d5/2 peakobserved as a single peak at binding energy of 182.2 eV,which is a good agreement to Zr 4+ .Fig. 7 shows the 3D AFM image of selectively grownZrO 2 thin film on OTS SAMs patterned Si(1 0 0) substrateat 450 1C for 2 h. The selectivity of thin film and the sharpboundary between ZrO 2 thin film area and OTS SAMs areclearly distinguished. The thickness of deposited ZrO 2 thinfilm was approximately 30–40 nm. The growth rate of ZrO 2thin films using Zr(O i Pr) 2 (tbaoac) 2 was much slower thanthat of TiO 2 thin films.OTS SAMs have been demonstrated as a promisingcandidate for a MOCVD resist layer which can block thesurface functional groups that are necessary for nucleationFig. 5. OM images of a ZrO 2 thin film deposited on the OTS patternedSi(1 0 0) substrate.Fig. 7. 3D and 2D AFM images of selective growth of a ZrO 2 thin film onSi(1 0 0) substrate.Fig. 6. SEM image of a ZrO 2 thin film deposited on the OTS patterned Si(1 0 0) substrate at (a) 450 1C for 2 h and (b) 450 1C for 4 h.