4:00 PM - 4:15 PM
▼ [12p-D419-9] The role of water in the synthesis of AlOx thin films by a mist chemical vapor deposition
Keywords:mist-CVD, Alumina, Water addition
The role of water as an additive during the synthesis of aluminum oxide (AlOx) thin films by mist chemical vapor deposition (mist CVD) was investigated. This study was based on deposition using aluminum acetylacetonate (Al(acac)3) and methanol (MeOH), while also exposing some films to water or methanol mists after fabrication. Analysis by AFM and FTIR spectroscopy established that the AlOx films fabricated from Al(acac)3 using methanol as the sole exhibited a distorted Al(OH) network, including a high concentration of OH groups. The addition of water to the Al(acac)3/MeOH precursor decreased the film deposition rate and also lead to marked reductions in both the surface roughness and -OH concentration. Exposing the Al(OH) films to water mist after synthesis resulted in etching together with the removal of -OH groups and decreases in surface roughness. Exposure to water induced no significant changes in the surface chemistry or morphology of AlOx thin films deposited at a MeOH:water volume ratio of 7:3. However, FTIR spectra demonstrated that exposing these AlOx films to a MeOH mist promoted the formation of Al(OH) bonds. Figure 1 shows the schematic of the growth surface for the MeOH:water ratios of 10:0 and 7:3. The results of this work indicate that the incorporation of -OH groups into the AlOx network generates both network distortion and inhomogeneity. It is also evident that water present during film growth removes -OH groups during the growth, resulting in the formation of a dense, uniform AlOx network. The effect of the substrate bias on the AlOx film properties will be also presented.