Vacuum-UV influenced design of polymers and dissolution inhibitors for next generation photolithography
摘要:
An overview of our 157 nm photoresist development activities is presented. Examination of the vacuum ultraviolet (VUV) absorbances of fluorinated monomers and polymers has provided knowledge that influenced copolymer design so that resist transparency in the vacuum-UV can be maximized. Partially fluorinated norbornenes and tricyclononenes (TCNs) have been incorporated into copolymers using metal-catalyzed addition and radical initiators. These materials have orders of magnitude higher transparency at 157 nm compared to their hydrocarbon analogues as measured by variable angle spectroscopic ellipsometry (VASE). We have also synthesized fluorinated dissolution inhibitors for use in a three-component resist system. The results of preliminary lithographic evaluations of resists formulated from these polymers are presented. (C) 2003 Elsevier Science B.V. All rights reserved.
Construction of trifluoromethylated quaternary carbons via Diels-Alder reactions of 2-(trifluoromethyl)propenoic acid derivatives: application to the synthesis of 16,16,16-trifluororetinal
摘要:
Diels-Alder reactions of 2-(trifluoromethyl)propenoic acid (1) and its 2,2,2-trifluoroethyl ester 2 with various dienes gave adducts in good yields. In Lewis acid catalyzed Diels-Alder reactions of 2, the combination of the Lewis acid and solvent proved to be crucial. For example, polymerization occurred in the case of TiCl4-CH2Cl2 and adduct formation was observed with TiCl4-toluene and TiCl2(O-i-Pr)2-CH2Cl2. In the TiCl4-catalyzed Diels-Alder reaction of the 2-(trifluoromethyl)propenoate ester 3 of D-pantolactone with butadiene, the formation of the R configurational quaternary carbon bearing the trifluoromethyl group was confirmed by X-ray crystallographic analysis of the adduct 20. No polymerization of ester 3 could be detected in the presence of TiCl4 in CH2Cl2. The reactivity difference between 2 and 3 in TiCl4-catalyzed Diels-Alder reactions may possibly be attributable to the stabilization of the 3-TiCl4 complex or weakening of Lewis acidity by coordination of the bidentate ester group of 3. The synthesis of all-trans-16,16,16-trifluororetinal (4), which is considered to be an important analogue for the study of retinal-binding protein, was conducted on the basis of these results. Comparison of the absorption maximum (362 nm) of 4 with other trifluororetinal 34 (362 nm) and 35 (382 nm) reported previously suggests the possibility of a large torsion of the conjugated system between the ring and the polyenal side chain in 4.