Method of forming a high transparent carbon film

A method of forming a transparent hydrocarbon-based polymer film on a substrate by plasma CVD, comprising:

• introducing a main gas consisting of a hydrocarbon gas (CαHβ, wherein α and β are natural numbers) and an inert gas at a flow ratio (R) of CαHβ/inert gas of 0.25 or less into a CVD reaction chamber inside which a substrate is placed, wherein the liquid monomer has a carbon/hydrogen ratio (C/H) of 0.5 or higher and has no benzene ring;
• and
• forming a hydrocarbon-based polymer film on the substrate by plasma polymerization of the gas at a processing temperature (T° C.) wherein T≦(−800R+500) and T<350, at a pressure of less than 1000 Pa, and at an RF power density of about 0.01 W/cm2 to about 20 W/cm2,
• wherein the flow ratio and the processing temperature are controlled, thereby forming the hydrocarbon-based polymer film having an extinction coefficient of 0.05 or less as measured at a lighting optical wavelength of 633 nm, a modulus of 20 GPa or higher, and a hardness of 4 GPa or higher.