Effect of Comonomer Structure on Dissolution Characteristics: ArF Negative Resist System Using Androsterone Derivative with .DELTA.-Hydroxy Acid.

Development of high-performance negative-tone resists for 193-nm lithography

“…16 The ketone structure of 3-β-acryloyloxy-androsterone was converted to δ-lactone by Baeyer-Villiger oxidation. 22,23 Norbornane lactone acrylate 11 (NLA) (Figure 1) was synthesized according to the literature.…”

“…The authors next developed a negative-tone resist system based on acid-catalyzed intramolecular esterification of δ-hydroxy acid. 15,16 To improve the transparency and shelf life of the resist, an acrylate polymer with a pendant structure consisting of an androsterone derivative with δ-hydroxy acid (Scheme 2) was developed. It is well known that a steroid structure such as androsterone shows high transparency and high dry-etching durability.…”

IBM-JSR 193-nm negative tone resist: polymer design, material properties, and lithographic performance

“…The resulting increase in molecular weight of the polymer would render it insoluble in aqueous developer thus enabling negative-tone imaging. The use of acrylic acid or carboxylic acid derivatives to impart base solubility in 193nm negative resists due to their high dissolution rate in 0.263N TMAH developer has been reported in literature 7,10,11,14 . However, being highly acidic (pKa ~ 3-6) the presence of these units may also cause swelling of the crosslinked matrix in the developer leading to microbridging which is the principal cause limiting resolution in negative tone resists 7,10,14 .…”

“…Others have suggested that penetration of developer into the exposed, insoluble polymer matrix resulting in swelling may be to blame 7 . Even though several 193nm negative resist development efforts have been reported, a negative resist capable of outperforming a positive process has yet to be achieved [7][8][9][10][11][12][13][14][15] .…”