Alicyclic polymers

Several polymethacrylates, primarily alkyl esters, were compared with a novolac resist in terms of etch rates in CF4 and Ar plasmas. The alkyl groups examined included methyl, terf-butyl, cyclohexyl, norbonyl, adamantyl, and benzyl [226]. The polymerization of alicyclic methacrylates was pioneered by Otsu, who has demonstrated facile polymerization of bulky methacrylates and reported high Tg of this class of polymethacrylates [230]. It has been found that alicyclic polymers exhibit better dry etch resistance than acyclic esters and that the dry etch durability is increased by an increase in the number of rings. Thus, poly(adamantyl methacrylate) is as stable as a novolac resist under dry etch conditions. A 30/70 copolymer of adamantyl methacrylate with ter/-butyl... 

While ring-opening polymerization of camphorsultam was attempted futilely to prepare a new polymer containing a bicyclic structure and a new acidic sulfonamide group in the backbone [115b], radical cyclopolymerization was exploited in the synthesis of 193 nm alicyclic polymers (Fig. 79). Transannular polymerization to form polynortricyclene bearing tert-butyl ester was utilized in radical copolymerization with MA (Fig. 79) [275]. Radical cyclopolymer-... 

Kaimoto, K. Nozaki, S. Takechi, andN. Abe, Alicyclic polymer for ArF and KrF excimer resist based on chemical amplification, Proc. SPIE 1672, 66 (1992). 

S.3.3 Ester-protected alicyclic polymer resist platform... 

The second platform of ester-protected positive resists designed for ArF lithography is the alicyclic polymer platform,which was first developed at the University of Texas at Austin,and involves resists in which the alicyclic units with pendant ester-protecting groups, acidic groups, and adhesion-promoting groups constitute the backbone of the polymer. Resist polymers of this platform... 

For complete detail, please see, U. Okoroanyanwu, Alicyclic polymers chemistry and argon flouride exciplex laser lithography, Ph.D. Thesis, The University of Texas at Austin (1997). 

Scheme 7.38 Free radical copolymerization of various alicyclic monomers initiated by (1) azoisobutyronitrile (AIBN) in THF, and (2) di-tert-butyl peroxide (DTBP) in propylene glycol monomethylether acetate, and used in the synthesis of the alicyclic polymer resist materials for ArF lithography, pioneered at the University of Texas at Austin in 1995. Note that although only 2,3-enchainment of the cyclic olefins is shown above the scheme, 2,7-enchainement is also possible, as reported by Gaylord and co-workers. ...

A number of alicyclic polymers designed for resist applications and following the University of Texas at Austin approach have been reported. The most prominent among them include these listed below and marketed under the brand name... 

Figure 7.16 SEM images of 150-nm line features printed in the first commercial version of the alicyclic polymer resist platform, based on poly(dinorbornene-a/t-maleic anhydride), and marketed under the brand name of ATOl by the JSR Corporation. Exposure wavelength was 193 nm.

The acrylate/alicyclic polymer hybrid polymer platform (XLII) pioneered at Bell Labs in 1996. 

Wallow, F.M. Houlihan, O. Nalamasu, E.A. Chandross, T.X. Neenan, and E. Reichmanis, Evaluation of cycloolefin maleic anhydride alternating copolymers as single layer photoresists for 193 nm photolithography, Proc. SPIE 2724, 355 (1996) F.M. Houlihan, T.I. Wallow, A. Timko, E. Neria, B. Hutton, R. Cirelli, O. Nalamasu, and E. Reichmanis, Recent advances in 193 nm single layer photoresists based on alternating copolymers of cycloolefins, Proc. SPIE 3049, 84 (1997) J. H. Park, S. J. Kim, S. Y. Park, and H. Lee, ArF photoresist system using alicyclic polymer, Proc. SPIE 3049, 485 (1997). 

Infrared spectroscopy provides a convenient method for studying the deprotection kinetics of resist polymers. For example, the deprotection kinetics of some alicyclic polymer resist systems comprising (i) poly(methylpropyl bicyclo[2.2.1]-hept-5-ene-2-carboxylate-co-bicyclo[2.2.1]hept-5-ene-2-carboxylic acid) (trivial name poly(carbo-t-butoxynorbomene-co-norbornene carboxylic acid) [poly(CBN-co-NBCA)] (I) and (ii) poly(methylpropyl bicyclo[2.2.1]hept-5-ene-2-carboxylate-co-maleic anhydride) (trivial name poly(carbo-t-butoxynorbomene-co-maleic anhydride) [poly(CBN-aZr-MAH)] (11) and containing triphenylsulfonium... 

The methodologies reported here follow from U. Okoroanyanwu, J.D. Byers, T. Cao, S.E. Webber, and C.G. Willson, Deprotection kinetics of alicyclic polymer resist systems designed for ArF (193 nm) lithography, in Polymers for Micro and Nano Patterning Science and Technology, H. Itoh, E. Reichmanis, O. Nalamasu, and T. Ueno, Eds., pp. 174 190, American Chemical Society, Washington, DC (1998). 

Figure 11.49 Effect of electron-beam curing of resists based on poly(methacrylate) platform and hybrid methacrylate/alicyclic polymer platform on polygate etch. Electron-beam curing improves etch resistance by up to 50% relative to the control (uncured) sample. Processing was done in a nitrogen environment of the ElectronCure Electron Beam Process Chamber utilizing these electron-beam parameters 3.75 keV, 6 mA, 2000 pC/cm. The wafer temperature of the standard (Std.) process was not controlled, that for the electron-beam standard cure (ESC) process was kept at a medium temperature, that for the low-temperature (LT) process was maintained at a iow temperature, whiie that for the control was at room temperature. [After R. Dammel, Practical resist processing, SPIE Short Course No. SC616 (2005).]...

Okoroanyanwu and R. Subramanian, Interconnect structure with silicon containing alicyclic polymers and low k dielectric materials and method of making same with single and dual damascene techniques, U.S. Patent No. 6,475,904 (2002). 

Deprotection Kinetics of Alicyclic Polymer Resist Systems Designed for ArF (193 nm) Lithography... 

The deprotection kinetics of alicyclic polymer resist systems designed for 193 nm lithography was examined using JR and fluorescence spectroscopic techniques. A kinetic model was developed that simulates the deprotection of the resists fairly well. A new, simple, and reliable method for monitoring photoinduced acid generation in polymer films and in solutions of the kind used in 193 nm and deep-UV lithography was developed. This technique could find application in the study of diffusional processes in thin polymer films. 

Infra-red spectroscopy and fluorescence spectroscopy provide convenient methods for studying these processes. Using FTIR, we investigated the deprotection kinetics of some of our alicyclic polymer resist systems (2,3) (containing triphenylsulfonium hexafluoroantimonate) that were exposed to 248 and 193 nm... 

Materials. Alicyclic polymers such as poly(CBN-a/t-MAH) and poly(CBN-co-NBCA) were synthesized by free radical and Pd(II)-catalyzed addition polymerization techniques, respectively, the details of which are given in References (2,3) and in (Okoroanyanwu, U. Byers, J. Shimokawa, T. Willson, C.G. Chem. Mater., 1998, in press) (Okoroanyanwu, U. Shimokawa, T. Byers, J. Willson, C.G. Chem. Mater., 1998, in press). Triphenylsulfonium hexafluoroantimonate (TPSHFA) was prepared according to the literature procedure (5). CD 11 anti-reflective coating was obtained from Brewer Scientific Company. BARL antireflective coating was obtained from IBM Corporation. PD-523AD developer, 0.2 IN aqueous tetramethylammonium hydroxide solution with surfactant was obtained from Japan Synthetic Rubber Company. LDD-26W developer, 0.26N aqueous tetramethylammonium hydroxide, was obtained from Shipley Company. 

IR Measurements on Radiation-Exposed Alicyclic Polymer Photoresist Films. 

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