Numerical Investigation for Scale-Up of an Electron Cyclotron Resonance Plasma for Fluorine-Doped Tin Oxide Thin Film Production

A low-temperature process is required to deposit fluorine doped tin oxide (FTO) as a transparent conductive oxide on polyethylene terephthalate (PET) substrate, as the latter is polymeric and has a low melting point. An electron cyclotron resonance (ECR) plasma system is the best way to deposit metal oxide with high transparency and electrical conductivity at temperatures below 100 degrees C. Characteristics of an ECR plasma include its high ionization energy and electron density; however, its use is limited in large-scale deposition. In order to overcome this limitation, a large-scale ECR plasma system with a dual microwave generator was designed by numerical investigation of a laboratory-scale ECR plasma system. FTO films prepared in the laboratory-scale and large-scale systems were compared. The change in electrical resistivity and optical transmittance with deposition pressure in the large-scale ECR plasma system with dual linear microwave generator is similar to that observed in the laboratory-scale ECR plasma system. The velocity distribution of active species near the substrate in the large-scale ECR plasma system showed a very similar pattern to that in the laboratory-scale ECR plasma system over a range of 1.5 x 10(-2) to 0.8 x 10(-2) m/s. The electrical resistivity and optical transmittance of FTO films deposited by a large-scale ECR plasma system using a dual microwave generator had respective values of 4.3 x 10(-3) similar to 9.18 x 10(-3) Omega . cm and 86.5 similar to 88.2%.