Thin tatanium dioxide films as interlayers in trilayer resist schemes.

The use of thin titanium dioxide (TiO sub 2) films as interlayers in trilayer resist schemes was investigated. A thin (30-200angstroms ) TiO sub 2 layer was formed on the surface of a hard-baked (HB) HPR206 film by the reaction of titanium tetrachloride with water adsorbed on the surface of the film. This reaction was accomplished using a process similar to the hexamethyldisilazane (HMDS) treatment that is employed to remove water from-bare silicon wafers to improve photoresist adhesion. Several variables that affect the thickness of the TiO sub 2 films that result from the TiC1 sub 4-film reaction were investigated. We discuss these variables, various etching techniques for transfer of the resist pattern into the TiO sub 2 interlayer and defects in the TiO sub 2 films. Using a trilayer resist process with a thin TiO sub 2 interlayer that acts as the mask in the final reactive-ion etch transfer step, 0.8micron features were transferred from a top MP 1400 photoresist film into a 1.8micron thick HB206 film.