Low Resistive TiO₂ Deposition by LPCVD Using TTIP and NbF₅ in Hydrogen-Ambient

Abstract

Low resistive TiO 2 layer was deposited by low pressure chemical vapor deposition (LPCVD) at pressure around 0.25 Pa using titanium-tetra-iso-propoxide (TTIP) and NbF5 in H₂-ambient. Acti-vation energy for the deposition rate on the temperature was significantly decreased to 120 kJ/mol as compared with 228 kJ/mol for the deposition in H₂ without NbF 5 . The deposition rate linearly increased with NbF 5 supply rate but gradually decreased with H 2 supply rate indicated that F on the deposition surface acts as catalyst for TTIP-dissociation but is non-activated by hydrogen. Resistivity of the layer was decreased by NbF 5 supply depending on the deposition temperature with the activation energy of 319 kJ/mol, whereas the energy was 244 kJ/mol for the layer deposited in H 2 without NbF 5 . The dependence of resistivity on NbF 5 . and H 2 supply rates suggested that the doping should be performed by sufficient NbF 5 and H 2 supply rate to improve the crystallinity. As a result of the optimization, the resistivity was successfully reduced to 5 × 10 -2 Ω · cm. Optical transmission spectra in UV-Vis region indicated that significant absorption observed for the layer deposited in H 2 was notably decreased by using NbF 5 . The improved optical property was better than that for the layer deposited in O 2 -ambient.