Low-Temperature Deposition of Polycrystalline Titanium Oxide Thin Film on Si Substrate Using Supercritical Carbon Dioxide Fluid

Abstract

A novel technique for the deposition of oxide thin films using supercritical carbon dioxide (CO2) fluid was proposed for the large-scale circuit integration on a silicon (Si) substrate at a low temperature. Thin films of titanium oxide (TiO2) as a model material were fabricated from organometallic Ti(Oi-Pr)2(dpm)2 source on (100)Si substrates in supercritical CO2 fluid. The film deposition was accomplished using a flow-type supercritical fluid deposition apparatus designed on the basis of metal-organic chemical vapor deposition (MOCVD) systems. Flat films were fabricated on (100)Si substrates at a faster source delivery (fluid flow rate: 2.0–10.0 cm3/min), while granular deposits owing to homogeneous nucleation in the bulk supercritical CO2 fluid appeared on the substrates at a slower source delivery (fluid flow rate: 1.0 cm3/min). The amount of TiO2 deposited decreased gradually with increasing the temperature of CO2 fluid, which would be related to the change in the density of CO2 fluid. The crystalline TiO2 film was deposited on the (100)Si substrate at a substrate temperature of 80–120°C and fluid temperature/pressure of 40°C/8.0 MPa, at which the decomposition of organometallic Ti(Oi-Pr)2(dpm)2 source was accomplished. These results indicated that the supercritical CO2 deposition technique is suitable for the large-scale circuit integration on Si substrates.