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We have designed and developed a variety of hexafluoroalcohol (HFA) pendant methacrylate monomers and the corresponding imaging polymers for ArF lithography. It was found that HFA side chains are critical for "swelling free" dissolution properties for the polymers and resists. Through the incorporation of HFA functionalities, ArF resists can obtain linear dissolution properties commonly seen in 248nm ESCAP resists. These improved dissolution properties in turn significantly reduce PEB sensitivity of higher activation protecting group (e.g., methyladamantanyl) based ArF resists. We have also showed that the fluorine impact on etch rates can be modulated through the insertion of cyclic and aliphatic spacers between the main chain and the HFA functionalities. The key application space for HFA-methacrylate resists appears to be trench level lithography. It was also demonstrated that these HFA materials are compatible with immersion lithography and result in dramatically improved process windows for iso trench features, in addition to other lines/space features.

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.

The progress of developer base into films of terpolymers of norbornene−maleic anhydride and acrylic acid was shown to be a percolation process with a critical site concentration of x(c) = 0.084, implying that every acrylic acid site in the terpolymer makes 12 monomer units of the polymer water compatible. Using these terpolymers, the dissolution inhibition mechanism for two types of common additives, tert-butyl carboxylate (e.g., cholates, cyclohexanecarboxylates, and malonates) dissolution inhibititors and onium salt photoacid generators (PAG's), were examined. Additionally, the dissolution promotion mechanism of carboxylic acids released from acidolysis of tert-butyl esters was investigated. For a wide range of cholates and other tert-butyl carboxylate derivatives, increasing hydrophobicity is a good predictor of increased dissolution inhibition. The molar dissolution promotion ability of a carboxylic acid increases with increasing number of both carboxyl and hydroxyl ester functional groups. For onium ...

Using terpolymers of Poly(norbornene-alt-malefic anhydride-co-acrylic acid) [P(NB/MA/AA)], the dissolution inhibition mechanism for two types of common additives in 193nm resist formulations, tert-butylcarboxylate (e.g. tert-butyl cholate) dissolution inhibitors (DI) and onium salt photoacid generators (PAC's) were examined. For simple cholate ester derivatives, increasing interactions with maleic anhydride repeating units paralleled the dissolution inhibition (tert-butyllithocholate>tert-butyldeoxycholate>tert-butylcholate). For a wider range of cholate derivatives, increasing hydrophobicity as measured by logPoct or the cloud point formation in water/acetone mixtures, is a good predictor of increased dissolution inhibition. Increases in dissolution promotion appeared to track with the number of carboxylic acid moieties and the hydrophobicity of carboxylic acid moieties released upon acidolytic cleavage of carboxylate esters. Finally, for onium salt PAC's, increasing the size of fluorinated anions decreased dissolution inhibition. This may be because these anions offer more steric hindrance, which disfavors interactions with the terpolymer matrix. The nature of this interaction may be that of a PAG with carboxylic acid as judged from modeling studies with acetic acid in which increasing strength of the interaction correlated with increased dissolution inhibition (triflate>nonaflate> perflurooctanesulfonate)

The performance of a 193nm single layer resist based on a norbornene-malefic anhydride matrix resin has been optimized through a series of statistical design experiments. The SDE demonstrated the importance of setting the PEB temperature above the SB temperature with optimum performance being observed at a SB of 150°C and a PEB of 160°C. The lithographic performance of the resist was also strongly influenced by polymer composition, specifically acrylate loading and blocking level. Optimizing the composition of the polymer, gave resists with high etch resistance, square profiles and 0.130 micron dense line ultimate resolution in 0.5 micron thick films. The resist formulations are compatible with industry standard 0.262N TMAH. During exposure the resist does not suffer from the outgassing of volatile species (less than 1e12 molecules/cm2 x sec). A new thermally curable undercoat for bi-layer application has also been developed whose optical properties have been optimized to reduce reflectivity at the desired wavelength. The reflectivity has been reduced by a factor of eight over an earlier UV-cured version.

In this paper we report the results of a feasibility study of manufacturability of processes using plasma polymerized methylsilane (PPMS) as both a single-layer and a bilayer resist in both negative and positive tone development modes. PPMS has shown great promise as the basis for an all dry lithographic process. The photosensitive polymer is deposited in a low power plasma of methylsilane gas and is comprised of a Si-Si bonded network. PPMS undergoes efficient photo-oxidative crosslinking upon exposure to 248 or 193nm light in air to form an oxide-like material (PPMSO). We have identified several structural differences of films deposited at different temperatures and have correlated those differences to the air stability and the photosensitivity of PPMS films. We have also examined the effect of laser pulse power and repetition rate on the efficiency of exposure and conclude that the rate of oxygen diffusion into the film limits the effectiveness of high laser power for increasing the throughput of an exposure tool. We have concluded that positive tone PPMS processing is not practical because of the slow diffusion of oxygen through the film, required for effective photo-oxidation of PPMS to occur.

The intense absorption of aromatic molecules at 193 nm severely limits the use of conventional matrix aromatic resins such as novolac, poly vinyl phenol for 193 nm lithography. This paradigm shift in resist design provides opportunities for new chemistries and process schemes to provide the required aqueous base solubility, etch resistance, resolution, photospeed and process latitude. In addition, regulatory constraints on the volatile organic emissions (VOC) also provide opportunities to design revolutionary resist schemes that not only address the lithographic performance requirements but also alleviate the environmental safety and health (ES&H) aspects of resist technology. In this paper, we will analyze the several resist options available for 193 nm lithography and provide results for evolutionary single layer, bilayer and revolutionary “all-dry” plasma polymerized methyl silane (PPMS) resist schemes. For single layer schemes, we have synthesized several co- and terpolymers with cycloolefins, maleic anhydride and acrylates (acrylic, methacrylic acids and esters) and have used the protected polymers as matrix resins in three component systems with a photoacid generator (PAG) and dissolution inhibitor(s) (DI). Alternately, we have used the unprotected terpolymer with DI's and PAG in three component systems. The lithographic results for single layer and bilayer resist materials were obtained at 193 nm using a 0.55 NA Nikon or 0.56 NA ISI (Integrated Solutions Inc.) small field exposure systems. Single layer resist materials showed at least 0.16 μm l/s pair resolution and modulation down to 0.14 μm l/s pairs using a formulation and process optimized at 248 nm. We have also evaluated the performance of P(SI-CMS) (poly(trimethyl silyl methyl methacrylate-co-chloromethyl styrene), a negative e-beam resist, at 193 nm and have obtained 0.25 μm l/s pair resolution without much optimization. Structure-activity relationships between the polymer properties and lithographic performance for this system have been identified. The results obtained for PPMS, a plasma deposited all-dry resist technology, on the 193 nm Micrascan (0.50 NA) were also very encouraging. Again using a non-optimized process, we have obtained at least 0.15 μm l/s pair resolution in a bilayer scheme.

We review our recent measurements of the Knight shift and spin-lattice relaxation time of the nuclei located in n-doped GaAs quantum wells using optically pumped NMR, for Landau level filling and temperature . ( the electron spin polarization ) drops precipitously on either side of , which is evidence that the charged excitations of the ground state are finite-size skyrmions. For , the data are consistent with a many-body ground state which is not fully spin polarized, with a very small spin excitation gap that increases as .

An optical pumping technique was used to enhance and localize nuclear magnetic resonance (NMR) signals from an n-doped GaAs/Al0.1Ga0.9As multiple quantum well structure, permitting direct radio-frequency measurements of gallium-71 NMR spectra and nuclear spin-lattice relaxation rates (1/T1) as functions of temperature (1.6 K < T < 4.2 K) and the Landau level filling factor (0.66 < v < 1.76). The measurements reveal effects of electron-electron interactions on the energy levels and spin states of the two-dimensional electron system confined in the GaAs wells. Minima in 1/T1 at v approximately 1 and v approximately 2/3 indicate energy gaps for electronic excitations in both integer and fractional quantum Hall states. Rapid, temperature-independent relaxation at intermediate v values indicates a manifold of low-lying electronic states with mixed spin polarizations.

We propose and demonstrate a new approach to the determination of the conformations of molecules or monomers in noncrystalline solids. The method makes use of two-dimensional NMR exchange spectroscopy in combination with specific isotopic labeling. We present experimental results on specifically labeled poly(methyl methacrylate), poly(methyl acrylate), and poly(ethyl methacrylate). Through comparisons between the experimental and simulated two-dimensional spectra, we determine that the ester side groups of poly(methyl methacrylate) and poly(methyl acrylate) have planar, trans conformations and that the side groups of poly(ethyl methacrylate) are also predominantly in the planar, trans conformation in the noncrystalline solid state

Traditional implant layers are becoming increasingly complex in design and continuously pushing resolution limits lower. In response, developer-soluble bottom anti-reflective coatings (DBARCs) were introduced to meet these more challenging requirements. These DBARCs excelled over the traditional combination of single-layer resist and dyed resist/top anti-reflective coating (TARC). DBARCs offered the resolution and critical dimension (CD) control needed for the increasingly critical implant layers. Lithographic performance, focusing on CD control over topography and through-pitch behavior, demonstrated the inherent benefit of the DBARCs over the alternative solutions. Small-space residue testing showed the benefit of photosensitive (PS) DBARCs for cleanout of sub-100 nm trenches. A study of improved post-develop residue in various ion-implantation processes validated the use of new DBARC materials in implant layers.

We report the results of $^{133}\mathrm{Cs}$, $^{87}\mathrm{Rb}$, and $^{13}\mathrm{C}$ NMR measurements on the alkali-metal fullerides ${\mathrm{CsC}}_{60}$ and ${\mathrm{RbC}}_{60}$. Measurements of NMR spectra and spin-lattice relaxation rates provide clear evidence for phase transitions near 300 K in both compounds, with substantial changes in their electronic properties at the phase transitions. The high-temperature phases are paramagnets, with an exchange coupling of roughly 2 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ between electron spins that are localized primarily on ${\mathrm{C}}_{60}^{\mathrm{\ensuremath{-}}}$ ions. The $^{133}\mathrm{Cs}$ and $^{87}\mathrm{Rb}$ NMR frequency shifts and relaxation rates are determined by Fermi contact hyperfine couplings to the electron spins. The $^{13}\mathrm{C}$ relaxation rates are determined by dipolar hyperfine couplings. The electron-spin susceptibility is greatly reduced in the low-temperature phases

We describe a new two-dimensional NMR technique for structural studies of polycrystalline and noncrystalline solids. The technique is a variant of 2D exchange spectroscopy applicable to organic molecules, macromolecules, or molecular complexes that are doubly 13 C-labeled at a specific carboncarbon bond and singly 13 C labeled at a specific functional group. A Carr-Purcell sequence is used to obtain dipolar spectra in the t 1 dimension. Spectra in the t 2 dimension are determined primarily by the chemical-shift anisotropy. With spin diffusion among the labeled sites between the t 1 and t 2 periods, the resulting 2D spectra reveal correlations between the direction of the labeled bond and the orientation of the labeled functional group. Experimental spectra of two polycrystalline model compounds, dimethyl succinate and diammonium succinate, are presented and compared with simulations to illustrate the structural information contained in the 2D spectra.

Alkali metal fullerides (A x C 60 ) are a subject of considerable current interest because of the occurrence of superconductivity for A x C 60 at temperatures surpassed only by the high T c copper oxides. The preparation and characterization of A x C 60 (A = alkali metal, x = 2,3,4,6) by powder X-ray diffraction, NMR ( 13 C, 23 Na and 87 Rb), and d.c. magnetization are reported. The structures are described as intercalation compounds of the FCC structure of pristine c 60 or of hypothetical BCC or BCT structures. The structures and phase diagrams can be rationalized on the basis of ion size and electrostatic considerations. Only the A 3 C 60 compounds are metallic (and superconducting). The superconducting T c increases nearly linearly with unit cell size. EHT (Extended Huckel Theory) calculations and 13 C NMR relaxation measurements indicate higher densities of states for the higher T c compositions.

Lithographic scaling beyond the 22 nm node requires double patterning techniques to achieve pitch values below 80nm. The semiconductor industry is focusing on the development of several process techniques including track-only lithographic processing methods in order to reduce cost, cycle time and defects. Initial efforts for track-only double expose processes have relied on the use of chemical freeze materials to prevent inter-mixing of resists, and also by means of thermal curable materials. These two techniques may be complementary, in the sense that a chemical freeze may be very robust for protection of exposed regions, while thermal cure systems may provide strong protection of large unexposed areas. We will describe our results with mainly the thermal-cure double patterning resist materials, and the application of these materials to the fabrication of sub-80 nm pitch semiconductor structures. We will summarize the process window and defect capability of these materials, for both line/space and via applications.

Alkali metal fullerides (A x C 60 ) are a subject of considerable current interest because of the occurrence of superconductivity for A x C 60 at temperatures surpassed only by the high T c copper oxides. The preparation and characterization of A x C 60 (A = alkali metal, x = 2,3,4,6) by powder X-ray diffraction, NMR ( 13 C, 23 Na and 87 Rb), and d.c. magnetization are reported. The structures are described as intercalation compounds of the FCC structure of pristine c 60 or of hypothetical BCC or BCT structures. The structures and phase diagrams can be rationalized on the basis of ion size and electrostatic considerations. Only the A 3 C 60 compounds are metallic (and superconducting). The superconducting T c increases nearly linearly with unit cell size. EHT (Extended Huckel Theory) calculations and 13 C NMR relaxation measurements indicate higher densities of states for the higher T c compositions.

The reductions of and fullerenes in o‐dichlorobenzene (ODCB) electrolytes under controlled potential and convection at rotating disk and ring‐disk electrodes (RDE and RRDE) illuminate several aspects of the electron transfer processes. The stability of the successive one‐electron transfer products (up to and ions) is demonstrated through the RRDE. The diffusion coefficients of both fullerenes in ODCB/0.5M tetra n‐butyl ammonium bromide were measured by two RDE techniques, Levich limiting current behavior and the frequency response of sinusoidal hydrodynamic modulation (SHM). The former gave values of at 25°C for and , respectively, and the latter results were theoretically consistent with the Schmidt number of 17,400 so calculated, confirming the number of electrons transferred without the aid of Faraday's law. Voltammograms of the SHM current at the RDE show kinetic effects at the foot of each successive wave.

We use $^{31}\mathrm{P}$ nuclear-magnetic-resonance (NMR) spectra to measure the degree of cation ordering in thin films of the semiconductor alloy ${\mathrm{Ga}}_{0.5}$${\mathrm{In}}_{0.5}$P grown by organometallic vapor-phase epitaxy. We show that the five possible ${\mathrm{Ga}}_{\mathit{n}}$${\mathrm{In}}_{4\mathrm{\ensuremath{-}}\mathit{n}}$P clusters in ${\mathrm{Ga}}_{\mathit{x}}$${\mathrm{In}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$P give rise to resolved NMR lines under magic-angle spinning, allowing a determination of the degree of cation ordering from the relative areas of the five lines. The ordering is shown to be weak (order parameter \ensuremath{\le}0.6) even in films that appear highly ordered in transmission electron microscopy.

We report the results of $^{13}\mathrm{C}$ NMR measurements on ${\mathrm{K}}_{3}$${\mathrm{C}}_{60}$ and ${\mathrm{Rb}}_{3}$${\mathrm{C}}_{60}$ in the normal and superconducting states. Electronic densities of states at the Fermi energy in the normal-state and energy gaps in the superconducting state are estimated from spin-lattice-relaxation data. Implications of the relaxation and spectral data for the electronic properties of these materials are discussed.

We derive an expression for the rate of spin diffusion between 13C nuclei based on a simple model appropriate for organic solids. In this model, couplings between carbons and protons and among protons are included only as a source of fluctuating local magnetic fields at the carbon nuclei. Our results are essentially equivalent to the results of previous calculations in which the surrounding protons are treated quantum mechanically using memory function formalisms.

The recent synthesis of macroscopic quantities of spherical molecular carbon compounds, commonly called fullerenes, has stimulated a wide variety of studies of the chemical and physical properties of this novel class of compounds. We discovered that the smallest of the known fullerenes, C60, could be made conducting and superconducting by reaction with alkali metals. In this paper, an overview of the motivation for these discoveries and some recent results are presented.

We characterize the molecular reorientational dynamics in two phases of solid ${\mathrm{C}}_{60}$ with $^{13}\mathrm{C}$ NMR measurements. A change in the nature of the dynamics, indicated by a change in kinetic parameters extracted from spin-lattice relaxation data, occurs at the phase transition at 260 K. Above the transition, the molecules appear to execute continuous rotational diffusion; below the transition, they appear to jump between symmetry-equivalent orientations. This interpretation is consistent with the x-ray-diffraction results of Heiney et al. as well as our NMR relaxation and spectral data.

Crystals of C60 or C70 cocrystallized with n-pentane grow as elongated, ten-sided columns. X-ray diffraction shows ordering of C60 or C70 molecules along the column and a remarkable tenfold symmetry normal to the column. The ratio of the x-ray-diffraction vectors of the two lowest-order diffraction spots is nearly equal to the “golden ratio,” τ. Despite these similarities with decagonal, quasicrystalline order, the diffraction indicates crystalline order with a twinned unit cell.

Treatment of iodocyclohexane with Bu 2 CuLi.LiI yields substantial amounts of butylcyclohexane, cyclohexane, cyclohexene, bicyclohexyl, and octane. Trapping experiments demonstrate that the bulk of these products derive from cyclohexyl radicals, indicating that an electron-transfer mechanism is operative. Some of the cyclohexane and bicyclohexyl is traced to transmetalation. Likewise, 1-methyl-1-cyclohexyl iodide and 2-heptyl iodide react via electron transfer, whereas cyclohexyl bromide, 1-heptyl iodide, and 1-heptyl bromide do not. These results are in harmony with House's hypothesis that electron transfer from organocuprates occurs when the reduction potentials of the substrates are more positive than −2.35 V

We describe a method for measuring nuclear magnetic dipole—dipole couplings in NMR spectra of solids undergoing rapid magic angle spinning (MAS). We show in theory, simulations, and experiments that the couplings, which are averaged out by MAS alone, can be recovered by applying simple resonant radiofrequency pulse sequences in synchrony with the sample rotation. Experimental 13 C dipolar powder pattern spectra of polycrystalline ( 13 CH 3 ) 2 C(OH)SO 3 Na obtained in a two-dimensional experiment based on this method are presented. The method provides a means of determining internuclear distances in polycrystalline and noncrystalline solids while retaining the high resolution and sensitivity afforded by MAS.

The intramolecularly H-bonded cis enolic form of malondialdehyde in chloroform is converted to an intermolecularly H-bonded trans enol by methoxy compounds such as methanol and 3,3-dimethoxypropanal. «Polar impurities» such as acetone and dioxane do not induce this effect

The combination of immersion lithography and reticle enhancement techniques (RETs) has extended 193nm lithography into the 45nm node and possibly beyond. In order to fulfill the tight pitch and small critical dimension requirements of these future technology nodes, the performance of 193nm resist materials needs to further improve. In this paper, a high performance 193nm photoresist system based on fluorosulfonamide (FSM) is designed and developed. The FSM group has good transparency at 193nm. Compared to the commonly used hexafluoroalcohol (HFA) group, the trifluoromethyl sulfonamide (TFSM) functionality has a lower pKa value and contains less fluorine atoms. Polymers containing the TFSM functionality have exhibited improved dissolution properties and better etch resistance than their HFA counterparts. Resists based on the FSM-containing polymers have shown superior lithographic performance for line, trench and contact hole levels under the 45nm node exposure conditions. In addition, FSM resists have also demonstrated excellent bright field and dark field compatibility and thereby make it possible to use one resist for both bright field and dark field level applications. The structure, property and lithographic performance of the FSM resist system are reported.

Over a period of last several years 193 nm immersion lithography from a remote and unlikely possibility gradually became a reality in many fabrication facilities across the globe and solid candidate for high volume manufacturing for the next generation technology node. It is being widely understood in the industry that top-coatless resist approach is a desirable final stage of the immersion process development. However creating low-defect high performance top-coatless resist materials requires understanding of the fundamental material properties of the top layer, responsible for leaching suppression, immersion fluid meniscus stability, and in this way enabling high speed low-defect scanning. While a lot of progress has been made in implementing specific top coat materials into the process flow, clear understanding effects of the top coat properties on the lithographic conditions and printing capability is still lacking. This paper will discuss top coat materials design, properties and functional characteristics in application to novel fluoroalcohol polymer-based immersion top coat. We have used our fluoroalcohol based-series designs (titled MVP top coat materials further on in the paper) as a test vehicle for establishing correlations between top coat performance and its physical and chemical properties including hydrophobicity, molecular weight/dispersity etc. Effects of polymer-solvent interactions on the contact angle and characteristics of the top coat material are explored, providing valuable understanding transferable to design of new generation top coats and top-coatless materials. Our resultant new designs demonstrated excellent lithographic performance, profiles and low leaching levels with commercially available resist and high receding contact angles, comparable to the commercial top coat materials.

The focus of this paper is to utilize the acidity of hexafluoroalcohol (HFA) in addressing performance deficiencies associated with current 193nm methacrylate resist materials. In this study, we have designed and developed a variety of HFA pendant methacrylate monomers and the corresponding imaging polymers for ArF lithography. It was shown that typical swelling behavior observed in methacrylate resists can be substantially reduced or eliminated by replacing commonly used multicylcic lactone polar functionalities with acidic HFA side chains. The incorporation of aliphatic spacers between HFA and polymer backbone were found to be more effective than cyclic hindered moieties, in achieving linear dissolution characteristics. The typical poor etch stability associated with fluorine atoms in HFA can be substantially minimized by designing side chains with a combination of appropriate cyclic and aliphatic moieties and fine-tuning the corresponding polymer compositions. PEB sensitivity of high activation energy protecting group (e.g., methyladamentyl group) based methacrylate resists can be substantially improved through the incorporation of acidic HFA side chains (6nm/C to

To make immersion lithography a reality in manufacturing, several challenges related to materials and defects must be addressed. Two such challenges include the development of water immersion compatible materials, and the vigorous pursuit of defect reduction with respect to both the films and the processes. Suitable resists and topcoats must be developed to be compatible with the water-soaked environment during exposure. Going beyond the requisite studies of component leaching from films into the water, and absorption of water into the films, application-specific optimization of photoresists and top coats will be required. This would involve an understanding of how a wide array of resist chemistry and formulations behave under immersion conditions. The intent of this paper is to compare lithographic performance under immersion and dry conditions of resists containing different polymer platforms, protecting groups, and formulations. The compatibility of several developer-soluble top-coat materials with a variety of resists is also studied with emphasis on profile control issues. With respect to defects, the sources are numerous. Bubbles and particles created during the imaging process, material remnants from incomplete removal of topcoats, and image collapse as related to resist swelling from water infusion are all sources of yield-limiting defects. Parallel efforts are required in the material development cycle focusing both on meeting the lithographic requirements, and on understanding and eliminating sources of defects. In this paper, efforts in the characterization and reduction of defects as related to materials chemistry and processing effects will be presented.

The fullerene C(60) can be converted into two different structures by high pressure and temperature. They are metastable and revert to pristine C(60) on reheating to 300 degrees C at ambient pressure. For synthesis temperatures between 300 degrees and 400 degrees C and pressures of 5 gigapascals, a nominal face-centered-cubic structure is produced with a lattice parameter a(o) = 13.6 angstroms. When treated at 500 degrees to 800 degrees C at the same pressure, C(60) transforms into a rhombohedral structure with hexagonal lattice parameters of a(o) = 9.22 angstroms and c(o) = 24.6 angstroms. The intermolecular distance is small enough that a chemical bond can form, in accord with the reduced solubility of the pressure-induced phases. Infrared, Raman, and nuclear magnetic resonance studies show a drastic reduction of icosahedral symmetry, as might occur if the C(60) molecules are linked.

Fluorinated dissolution inhibitors (DIs) for 157 nm lithography were designed and synthesized as part of an ongoing study on the structure/property relationships of photoresist additives. The problem of volatilization of small DI candidates was observed from matrices such as poly(methyl methacrylate) (PMMA) and poly(hexafluorohydroxy-isopropyl styrene) (PHFHIPS) during post-apply bake cycles using Fourier Transform Infrared Spectroscopy (FT-IR). To avoid this problem, low volatility fluorinated inhibitors were designed and synthesized. Three fluorinated DIs, perfluorosuberic acid bis-(2,2,2,-trifluoro-1-phenyl-1-trifluoromethyl-ethyl) ester (PFSE1), perfluorosuberic acid bis-[1-(4-trifluoromethyl-phenyl)-ethyl] ester (PFSE2) and a fluorinated phenylmethanediol diester (FPMD1), largely remained in a PHFHIPS film during the post-apply bake. The dissolution behavior of the two fluorinated diesters was studied and found to slow down the dissolution rate of PHFHIPS with inhibition factors of 1.9 and 1.6, respectively. The absorbance of PHFHIPS films containing 10 wt% of the diester inhibitors is 3.6 AU/micron compared with an absorbance of 3.3 AU/micron for the polymer itself. The absorbance of 10% FPMD1 in PHFHIPS was measured as 3.5 AU/micron compared with an absorbance of 3.4 AU/micron for the polymer itself. Thus, the non-volatility and transparency of the fluorinated inhibitors at 157 nm as well as their ability to reduce the development rate of fluorinated polymers make them suitable for use in a 157 nm resist system.

formulated in a poly(norbornene/maleic anhydride/acrylic acid/tert-butyl acrylate) 193 nm single layer resin. A comparisonis made between formulations containing non-cholate Dl's, cholate based Dl's and formulations containing blends ofthe twodifferent types ofDI's. It was found that formulations containing the non-cholate materials tended to give T-topped profileswhile the formulations containing cholate based materials and blends containing as little as 1% cholate based DI did not.Keywords:Dissolution Inhibitors, 193 nm, blending.

ALKALI metal fuller ides exhibit superconductivity1–4 at temperatures surpassed only by the copper-oxide-based ceramics. Three types of stoichiometry and structure have been identified: A3C60 (ref. 5) (where A is K or Rb) with A+ cations intercalated in the face-centred cubic (f.c.c.) C60 structure, and A6C60 (ref. 6) or A4C60 (ref. 7) (where A is K, Rb or Cs) with body-centred arrays of C60 molecules. All A3C60 compounds reported so far are superconductors with transition temperatures that increase with unit cell size8,9. No successful preparation of bulk NaxC60 has been reported, although measurements of electrical conductivity10 and Raman11, ESR11 and photoemission12 spectra of thin films have given clear indications of NaxC60 formation. Here we report the synthesis and initial characterization of bulk NaxC60 (2≤x≤6) and mixed alkali phases Na2AC60 (where A is K, Rb, or Cs). All of these phases have intercalated f.c.c. structures. The Na6C60 structure has a Na4 cluster centred on the octahedral site. The Na2AC60 compounds superconduct for the larger A cations, but a crossover to nonsuperconducting behaviour occurs with decreasing cation size and correlates with a minimum in the unit cell volume.

The fundamental nature of the interactions between poly (norbornene-alt-maleic anhydride) based resins and cholate based dissolution inhibitors (DIs) were studied by FT-IR and NMR spectroscopy. We also studied the role that photo-acid generators (PAGs) play in the dissolution of these polymer resins. We attempted to disentangle the hydrophobic effects of the DIs and PAGs from the specific interactions (Van der Waal's, hydrogen bonding or ionic) that these materials have within the polymer system. We employed solubility studies of DIs and PAGs using cloud point determinations and dissolution inhibition experiments on spun films to determine the extent that hydrophobicity and polymer interactions play in development. We found that for simple cholate derivatives the interactions with maleic anhydride repeating units parallel the dissolution inhibition sequence (t-butyllithocholate > t-butyldeoxycholate > t-butylcholate). For a wider range of cholate derivatives, the cloud point in water is a useful predictive tool, in that it takes into account both the hydrophobicity and the propensity to interact with other moieties. Thus for these materials, dissolution inhibition is governed by both interactions between the DI and the polymer, and the hydrophobic nature of the DIs. In contrast, for the PAGs, the cloud point is not a good predictive tool for dissolution inhibition. We found for onium salt materials, that the extent of dissolution inhibition is predicated by the size of the anion. For example, large sterically hindered anions which give rise to PAGs that exhibit poor solubility in water, paradoxically also show poor dissolution inhibition. This may be because the steric hinderance disfavors interactions with the polymer matrix.

We have found that the progress of developer base into films of terpolymers of norbornene (NB)-maleic anhydride (MA) and acrylic acid (AA) is a percolation process with a critical site concentration of x(c) equals 0.084 which suggests that every acrylic acid site in the terpolymer of norbornene-maleic anhydride-acrylic acid can make 12 monomer units of the polymer water compatible. In practice these systems are being used with various tert-butyl esters of cholic acid as dissolution inhibitors. The cholates differ very much in their dissolution inhibition factors (lowest t-butyl cholate (1.3) to highest t-butyl lithocholate glutarate dimer (7.4). The change in these factors corrected for molarity follow the hydrophobic character of the dissolution as measured by log(p). A quick screening method has also been established to evaluate dissolution inhibitors based on our observation that the cloud point (the volume % acetone in a water/acetone which gives persistent cloudiness) parallels the dissolution inhibiting power as measured by the dissolution inhibition factor. For dissolution promotion, optimal results are obtained with t-butyl 1,3,5-cyclohexanetricarboxylate (f equals -6.3) and poorest results with t-butyl lithocholate (f equals -2.8); this appears to track with the number of carboxyl groups and the hydrophobicity of the carboxylic acids. The Rmax found for resist formulations tracks well with these findings. Another factor in determining the ultimate achievable contrast is the degree of acidolytic deprotection achieved by the material. It appears that acidolyticaly cleaveable carboxylate esters with a higher concentration of electron withdrawing groups such as t-butyl 1,3,5-cyclohexanetricarboxylate are more effective.

Polymeric materials have found widespread use in the electronics industry in both the manufacturing processes used to generate today’s integrated circuits and as component structures in the completed devices. The broad applicability of polymers arises from the ability to design and synthesise such materials with the precise functionalities and properties required for a given application. Notably, polymeric materials have been used as lithographic imaging materials and as dielectric, passivation and insulating materials. To a large degree, the progress enjoyed by the device industry has relied on advances in the associated polymer materials technologies.

SUPERCONDUCTING K3C60 (ref. 1) has been shown2 to have an intercalated face-centred cubic (f.c.c.) structure, and other A3C60 compounds (where A is K, Rb or mixtures of K, Rb and/or Cs) form an isostructural series with superconducting transition temperatures up to 31.3 K (ref. 3). Recently we reported413C NMR studies of KxC60 for x

THE recent syntheses1,2 of macroscopic quantities of C60 have suggested possible applications in host–guest and organic chemistry, tribology, electrochemistry and semiconductor tech-nology. Here we report the preparation of alkali-metal-doped films of C60 and C70 which have electrical conductivities at room temperature that are comparable to those attained by n-type doped polyacetylene. The highest conductivities observed in the doped films are: 4Scm−1 (Cs/C60), 100 (Rb/C60), 500 (K/C60), 20 (Na/C60), 10 (Li/C60), 2 (K/C70). The doping process is reversed on exposure of the films to the atmosphere. At high doping levels, the films become more resistive. We attribute the conductivity induced in these films to the formation of energy bands from the π orbitals of C60 or C70, which become partially filled with carriers on doping. The smaller alkali metal ions should be able to fit into the interstices in the lattice without disrupting the network of contacts between the carbon spheroids. In the case of C60, this would allow the development of an isotropic band structure, and we therefore propose that these materials may constitute the first three-dimensional 'organic' conductors.

The authors report solid-state {sup 13}C NMR measurements on powder samples of C{sub 60} and of a mixture of C{sub 60} and C{sub 70}. The NMR results show that, at 296 K, C{sub 60} molecules rotate rapidly and isotropically in the solid state, while C{sub 70} molecules rotate somewhat more anisotropically. These results are consistent with the proposed spherical geometry of C{sub 60} and prolate spheroidal geometry of C{sub 70}. The rotational correlation time of C{sub 60} molecules in the solid state becomes greater than 50 {mu}s at about 100 K.

The fundamental nature of the interaction between the polymer matrix and the cholate based dissolution inhibitors are being studied by Fourier Transform-IR (FTIR) spectroscopy. It was found that the simple cholate derivatives undergo, in a blend with poly(norbornene-alt- maleic anhydride) and in a blend with the terpolymers poly(norbornene-alt-maleic anhydride-co-t-butylacrylate) and poly(norbornene-alt-maleic anhydride-co-acrylic acid), stronger interaction as seen by shifts in the OH region of the spectra than do blends with dimeric or oligomeric cholates.