Radiation Physics and Chemistry 62 (2001) 69–76 Fundamental studies of dissolution inhibition in poly(norbornene-alt-maleic anhydride) based resins F.M. Houlihan a, *, G. Dabbagh a , I. Rushkin a,1 , R. Hutton a , K. Bolan a , E. Reichmanis a , O. Nalamasu a , Z. Yan b,2 , A. Reiser b a Bell Laboratories, Lucent Technologies, 600 Mountain Avenue, Murray Hill, NJ 07946, USA b Institute of Imaging Science Polytechnic University, Brooklyn NY 11201, USA Abstract The dissolution inhibition mechanism for tert-butylcarboxylate (e.g. tert-butyl cholate) dissolution inhibitors and onium salt photoacid generators (PAG’s) were examined in terpolymers of poly(norbornene-maleic anhydride-acrylic acid) (P(NB/MA/AA)). For tert-butyl carboxylates, increasing hydrophobicity increased the dissolution inhibition ability. Dissolution promotion tracked with the number of carboxylic acid moieties and the hydrophobicity of carboxylic acids moieties released upon acidolytic cleavage of the tert-butyl carboxylate. For onium salt PAG’s, increasing the hydrophobicity and size of fluorinated anions decreased dissolution inhibition. r 2001 Elsevier Science Ltd. All rights reserved. Keywords: Dissolution inhibition; Photoacid generators; 193 nm resist 1. Introduction A class of single layer 193 nm chemically amplified resist (Reichmanis et al., 1991), based upon an alternat- ing copolymer of norbornene (NB) and maleic anhy- dride (MA) which also contains a small proportion (8% to 20%) of a third component such as tert-butyl esters of acrylic acid (TBA) containing an acid cleaveable moiety has recently been developed (Wallow et al., 1996; Houlihan et al., 1997c; Houlihan et al., 1998a, b). This paper will review the mechanism by which two different additives to this resist system, tert-butyl carboxylate dissolution inhibitors (DI’s) and photoacid generators (PAG’s), affect dissolution inhibition. This paper will summarize our work (Yan et al., 2000; Dabbagh et al., 2000; Houlihan et al., 2000a, b) on understanding the relationship between chemical structure of tert-butyl carboxylate DI’s and PAG’s and the dissolution behavior these impart to poly(norbornene-alt-maleic anhydride-co-acrylic acid) [P(NB/MA/AA)] and discuss how well these properties can be used to predict R max and contrast and overall lithographic performance. 2. tert-butyl carboxylates Our early work on tert-butyl carboxylate dissolution inhibitors dealt with the sub group, the tert-butyl cholates monomers, dimers and oligomers. (Wallow et al., 1996; Houlihan et al. 1997a–c; Houlihan et al., 1998a, b). The cholates are part of a wider group of compounds known as steroids. Steroids are known to undergo very specific interactions with substrates (Walli- man et al., 1997) due to either polar or van der Waals interactions. Consequently, we have looked for evidence of both mechanisms in the complexation of cholate DI’s with the P(NB/MA/AA) resin and determined which type of interaction correlates the best with observed dissolution inhibition trends as measured by dissolution inhibition factors (f(wt)). Values of f(wt) were obtained from Meyerhofer plots (Dammel, 1993) (i.e. log(R) *Corresponding author. Tel.: +1-908-582-4868. E-mail address: fmh@lucent.com (F.M. Houlihan). 1 Presently at Arch Chemicals Inc., East Providence, RI 02914. 2 Presently at Pall Inc Long Island NY. 0969-806X/01/$ - see front matter r 2001 Elsevier Science Ltd. All rights reserved. PII:S0969-806X(01)00414-5