Thick Positive Photoresist Research Articles

Thin titanium dioxide films as interlayers in trilayer-resist structures

The use of thin titanium dioxide (TiO2 ) films as interlayers in trilayer-resist structures was investigated in this paper. TiO2 layers, 30–200 Å thick, were formed on the surface of thick positive photoresist films by the reaction of titanium tetrachloride (TiCl4 ) with water adsorbed on the surface of the films. The TiCl4 -treated films served as the bottom two layers in trilayer-resist structures. Using a thin TiO2 interlayer that acted as the mask in the final reactive ion etching pattern transfer step, 0.5-μm features were transferred from a top imaging layer to a 1.2-μm-thick bottom layer with ∼0.05-μm linewidth loss. Processing variables that affect the thickness of the TiO2 films were investigated. We discuss these variables, etching techniques for transfer of the resist pattern from the top imaging layer to the TiO2 interlayer and pinhole defects in the TiO2 films.