May 12, 2005  14  US 2005/0100814 Al  [0158]  Dissolution Inhibitor  [0159]  Various dissolution inhibitors can be utilized in this  invention. Ideally, dissolution inhibitors (Dis) for the far and  extreme UV resists (e.g., 193 nm resists) are designed/  chosen to satisfy multiple materials needs including disso› lution inhibition, plasma etch resistance, and adhesion  behavior of resist compositions comprising a given DI  additive. Some dissolution inhibiting compounds also serve  as plasticizers in resist compositions.  [0160]  A variety of bile-salt esters (i.e., cholate esters) are  particularly useful as Dis in the compositions of this inven› tion. Bile-salt esters are known to be effective dissolution  inhibitors for deep UV resists, beginning with work by  Reichmanis et al. in 1983. (E. Reichmanis et al., "The Effect  of Substituents on the Photosensitivity of 2-Nitrobenzyl  Ester Deep UV Resists",  J.  Electrochem. Soc.  1983, 130,  1433-1437.) Bile-salt esters are  particularly attractive  choices as Dis for several reasons, including their availabil› ity from natural sources, their possessing a high alicyclic  carbon content, and particularly for their being transparent in  the Deep and vacuum UV region of the electromagnetic  spectrum (e.g., typically they are highly transparent at 193  nm). Furthermore, the bile-salt esters are also attractive DI  choices since they may be designed to have widely ranging  hydrophobic to hydrophilic compatibilities depending upon  hydroxyl substitution and functionalization.  [0161]  Representative bile-acids and bile-acid derivatives  that are suitable as additives and/or dissolution inhibitors for  this invention include, but are not limited to, those illustrated  below, which are as follows: cholic acid  (IV),  deoxycholic  acid  (V),  lithocholic acid  (VI),  t-butyl deoxycholate  (VII),  t-butyl lithocholate  (VIII),  and t-butyl-3-a-acetyl lithocho› late  (IX).  Bile-acid esters, including compounds  VII-IX,  are  preferred dissolution inhibitors in this invention.  [0162]  The amount of dissolution inhibitor can vary  depending upon the choice of polymer. When the polymer  lacks sufficient protected acid group for suitable image  forming a dissolution inhibitor can be used to enhance the  image forming properties of the photoresist composition.  [0163]  Other Components  [0164]  The compositions of this invention can contain  optional additional components. Examples of additional  components which can be added include, but are not limited  -continued  IV  V  IX  VIII  VI  COOH  cholic acid  COOH  H  deoxycholic acid  VII  COOH  H  lithocholic acid  Ot-Bu  H  t-butyl deoxycholate  0  Ot-Bu  H  t-butyl lithocholate  0  Ot_Bu  H  t-butyl-3a-acetyl lithocholate 