James B. O'Dwyer

Novel main chain scission positive-tone photoresists for 248-nm lithography with wide post-exposure processing latitude as an alternative to chemically amplified systems

While 248 nm chemically amplified resists systems offer excellent photospeed, they have introduced a number of processing difficulties including: environmental sensitivity, post exposure bake delay, acid diffusion, and critical dimension (CD) control. A novel positive acting resist which does not require diffusive dark reactions could eliminate some of these problems. One such class of resist would be those which utilize main chain scission to produce the latent image. If a main chain scission resist could be produced with good etch resistance and with E0 less than or equal to 50 mJ/cm2, it may be able to compete with the chemically amplified systems because of the ease of processing. We report the use of the novel photocleaving monomer 2,6-dinitro-1,4-benzenedimethanol which has been incorporated into positive tone 248 nm resist polymers. These resists operate both by molecular weight reduction and soluble functionality increase. The polymers also contain aromatic moieties which enhance their etch resistance profiles. Exposed films are developed in standard aqueous base (TMAH) developers and are stable for several days after exposure. Photospeeds are near or below the target E0 of 50 mJ/cm2. The use of these novel resists in the production of 0.25 to 0.35 micron 1/s is presented.