Search

This paper describes the formulation robustness of an 'ESCAP' type resist based on hydroxystyrene/t-butyl acrylate copolymer. The resist formation matrix consists of the polymer, a photo acid generator (PAG) and a base. The performance of the resist design was tested lithographically over 900 angstrom DUV-30 BARC as a function of variations in the PAG concentration and the base ratio to the PAG. The post exposure bake (PEB) temperature was also investigated as a third process variable in addition to the first two formation variables. The analysis of the results shows high performance tolerance to the formation variables. The resolution, focus latitude and exposure margin exhibited high tolerance to changes in the PEB temperature, PAG or base ratios.

The first report on the preparation, polymerization and copolymerization of two organotungsten vinyl monomers, (η 5 -vinylcyclopentadienyl)tricarbonylmethyltungsten (IV) and (η 5 -cyclopentadienylmethyl acrylate)tricarbonylmethyltungsten (IX) is described. Monomer IV was prepared from a reaction between formylcyclopentadienylsodium and hexacarbonyltungsten in DMF, followed by methylation with methyl iodide to produce (η 5 -formylcyclopentadienyl)tricarbonylmethyltungsten (III), and subsequent conversion of the latter into IV under phase transfer conditions employing triphenylmethylphosphonium iodide, 5 N sodium hydroxide and benzene. Moreover IX was obtained by sodium borohydride reduction of III, followed by treatment of the resulting carbinol with sodium hydride and subsequent reaction with acryloyl chloride. Monomer IV homopolymerized sluggishly, and copolymerized slowly with styrene under radical initiation in benzene solution. Copolymerizations of IV with methyl methacrylate, acrylonitrile, and N -vinyl-2-pyrrolidone were also successful. Monomer IX homopolymerized and copolymerized with styrene and with methyl acrylate. A styrene copolymer of IV when treated with iBuAlCl 2 and oxygen was active as a metathesis catalyst with 3-heptene.

X-ray exposure of selected novolac resins and commercial novolac-based resists show more varied end products and more crosslinking reactions than observed in the UV exposure. E-beam and x-ray induced reactions are somewhat similar. Novolac resin without the photoactive component (PAC) was shown to crosslink suggesting that x-ray and e-beam mechanisms must take this into account. Difference FTIR spectra were indicative of the structural changes. Mass spectrometry was less effective because of the volatility of PAC, although novolac resin without PAC was shown to contribute to the gaseous byproducts of exposure. The role of crosslinking of the novolac resin in process latitude and image reversal is discussed.

Organometallic polymers are useful in a variety of applications such as catalysts, UV absorbers, semiconductors, and antifouling agents.1–3 The construction of organometallic polymers can proceed by derivatizing preformed polymers with organometallic units3 or by preparing monomers with organometallic functions and polymerizing these monomers.2 Monomers 1–3 represent three examples of organometallic monomers which have been polymerized.4–7 In 2 6 and 3,7 the organometallic unit is far removed from the polymerizable vinyl group and does not directly effect the polymerization behavior via electronic effects. However, in vinylferrocene, 1, the organometallic moiety is directly attached to the vinyl group which leads, in turn, to some unusual effects in polymerization. For example, the rate of polymerization of vinylferrocene is first order in both monomer and initiator when initiated by AIBN in benzene (VP = 5.64 × 10−4[1]1.12 [AIBN]1.11).5 This is the result of a monomolecular termination mechanism caused by an electron transfer from iron to the radical center, followed by termination and subsequent decomposition to a paramagnetic Fe(III) center in the polymer. The presence of the transition metal, Fe, in the monomer permits such an unusual redox behavior which is impossible for ‘normal’ organic monomers (equation 1).

Model cresol novolac resins and photoactive compounds (PAC) based on polyhydroxybenzophenones were prepared according to known procedures. The components and resists formulated from them were exposed to X-rays from Aladdin, the electron storage ring at the University of Wisconsin. The loss of azide functionality and the conversion of PAC to acid or ester was monitored by FTIR difference spectrometry. The energy dependence of the sensitivity of conversion of diazonaphthoquinone to ketene was followed by monitoring the loss of diazide when exposed to synchrotron radiation. The effect of PAC functionality on the sensitivity and chemical pathways was studied. The relationship of structure and photon energy to lithographic performance are explored. We discuss the applicability of synchrotron radiation as an exposure source and FTIR as an analytical tool for the study of X-ray resist mechanisms.