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The looming industry transition towards EUV for high-volume manufacture of semiconductors has demonstrated the need for high sensitivity resists capable of delivering the resolution enhancements offered by the 13.5 nm platform. Inorganic and organometallic based resists have demonstrated themselves viable alternatives to traditional chemically amplified (CA) photoresists, as the EUV absorptivity enhancement of metal nuclei can enable efficient reactivity at minimal photon doses. Despite the demand for EUV photoreactive materials, relatively little has been reported on the fundamental reactivity of inorganic and organometallic compounds towards EUV that may enable the rational design of metal-based resists. To facilitate the design of next-generation metal-based resists, we have evaluated the reactivity of well-known metal-based model photosystems that undergo ligand-to-metal charge-transfer (LMCT), metal-to-ligand charge-transfer (MLCT), outer-sphere charge-transfer (OSCT), and ligand field (LF) based photochemistry in the UV and visible towards EUV and 100 KeV e-beam, with product characterization carried out by infrared, Raman, and UV-Vis spectroscopies. We will report the findings of these studies, emphasizing the relationships between quantum yields in the UV-Vis and EUV, role of the EUV absorption cross-section of the central metal, and trends in reaction classes and their relative sensitivity towards EUV.

As EUV approaches its insertion point into high volume manufacturing the semiconductor industry is increasingly focusing on photoresist performance. Recently metal containing resists have been proposed as alternatives to standard Chemically Amplified (CA) systems. Both approaches suffer from an incomplete knowledge of the EUV imaging mechanism. In particular the origin, number and fate of the secondary electrons believed to be active in the resist reactions is poorly understood. In this contribution we describe a study designed to try and characterize these processes and quantify the reactions that determine resist performances. We will describe experiments on a series of model CA systems doped with inorganic salts. Photoacid yields and relative rates of deprotection will be reported for metal salts that can be incorporated into polymer films at concentrations as high as 10 molal. In addition to comparing the relative performance at EUV we will also be characterizing the response at 248 nm and 100 KeV e beam. The results of these studies will be discussed in terms of the metal ion crossection, ionization potential and redox potential. In addition we will describe some unanticipated EUV reactivity of standard acid indicators that may impact the accepted electron yield/photospeed measurements that have been reported for EUV CA resists.

We report novel strategies to integrate block copolymer self-assembly with 193 nm water immersion lithography. These strategies employ commercially available positive tone chemically amplified photoresists to spatially encode directing information into precise topographical or chemical prepatterns for the directed self-assembly of block copolymers. Each of these methods exploits the advantageous solubility and thermal properties of polarity-switched positive tone photoresist materials. Precisely registered, sublithographic self-assembled structures are fabricated using these versatile integration schemes which are fully compatible with current optical lithography patterning materials, processes, and tooling.

A study of polymerization and some of the resulting properties of PAG-bound resist polymers based on a new triphenyl sulfonium fluoroalkyl sulfonate-containing methacrylate monomer is reported here. A low activation ester terpolymer containing this onium salt monomer was prepared and characterized. Our findings include the profound impact of residual monomer in the behavior of this material and the critical importance of polymer purification to remove unreacted ionic monomers in the preparation of polymer-bound PAGs. We have developed a polymer isolation process specifically tailored to remove unbound PAG so that the properties could be unambiguously investigated. And we report here the influence on properties of bound vs unbound PAG in this chemically amplified resist.

A photochemical path for formation of volatile S and acidolytic paths for formation of volatile Si and/or C during exposure to ultraviolet light have been identified for two silicon-containing bilayer photoresists using atmospheric pressure ionization mass spectrometry (API MS) and secondary ion mass spectrometry (SIMS). Si and S are of particular concern because of their potential for irreversible adsorption onto nearby optical coatings inside a lithographic tool, causing permanent detuning. We describe the analytical techniques used and report estimates for absolute numbers of Si and S atoms lost from the resists. The data show that Si bound through oxygen is easily cleaved from the polymer by photogenerated acid while Si bound through carbon is not. Photodissociation of perfluorosulfonic acid from the photoacid generators results in significant loss of S. The data are compared to previous studies, and the advantages and limitations of these techniques for photoresist chemistry characterization are disc...

Positive 193 nm bilayer resists based on polysilsesquioxanes (SSQ) and polyhedral oligomeric silsesquioxanes (POSS) are described. Fluoroalcohol is employed as an acid group. Our POSS materials are prepared by condensation of functional trialkoxysilane rather than by the commonly employed hydrosilylation on POSS and consist of T3 while the hydrosilylation method produces Q4 POSS. The condensation method is more suitable for scale-up, producing POSS materials with higher glass transition temperatures. The materials were analyzed by 19F, 13C, and 29Si NMR to determine composition and to quantify Q/T. The SSQ and POSS materials with the same compositions were compared in terms of the degree of hydrogen bonding by IR and the dissolution behavior by quartz crystal microbalance (QCM). Densities of the SSQ polymers were determined by X-ray reflectivity measurements and Rutherford back-scattering. Positive resists formulated with ternary SSQ and POSS were evaluated for contact hole and line/space applications, respectively. Characterization and lithographic performance of SSQ and POSS resists are described in detail.

Positive 193 nm bilayer resists based on polysilsesquioxane are described. Fluoroalcohol is employed as an acid group instead of carboxylic acid because of its more attractive dissolution properties. Polymers were carefully analyzed by 19F, 13C, and 29Si NMR to determine composition and to quantify residual acetyl, silanol, and Q/T. In an attempt to better understand the dissolution behavior of exposed resist films, the silsesquioxane resist polymers were partially and fully deprotected in solution with acid and their dissolution kinetics investigated by using a quartz crystal microbalance (QCM). The exposed areas of the silsesquioxane resists can have a very fast dissolution rate (Rmax) of >20,000 A/sec (or even >100,000 A/sec). Heating the fully deprotected model polymers to 150 °C did not reduce the dissolution rate much, suggesting thermal condensation of silanol end groups is insignificant. Model deprotected polymers containing triphenylsulfonium nonaflate were exposed to 254 nm radiation, baked, and subjected to QCM measurements in order to probe whether or not acid-catalyzed silanol condensation would reduce the dissolution rate. A combination of high dose and high temperature bake resulted in significant reduction of the dissolution rate in the silsesquioxane polymer containing a small trifluoroalcohol. However, the dissolution behavior of the polymer bearing a bulky norbornene hexafluoroalcohol was unaffected by exposure and bake. Chemical and development contrast curves were generated by using a thermal gradient hotplate and bake temperature effects investigated. A postexposure bake temperature effect was quite small. The process window of the silsesquioxane bilayer resists was comparable to that of a high performance commercial 193 nm single layer resist for both isolated and nested contact hole imaging, Superior performance of our silsesquioxane resist was demonstrated in patterned etch in comparison with a cycloolefin-maleic anhydride bilayer resist.

The use of organic solvents in the development of chemically amplified (CA) resists has been known since the introduction of DUV lithography into manufacturing over twenty years ago [1,2]. In this approach a negative tone image is produced using an aqueous base developable positive tone resist developed in an organic solvent. Recently there has been an increased interest in negative tone imaging due to superior performance for specific masking levels such as narrow trenches and contact holes [3]. Negative tone imaging of this type is based on differences in the polarity between the exposed and unexposed regions of the resist film. The dissolution contrast can be optimized by selecting a solvent with the proper match of solubility parameters (polarity, hydrogen bonding and dispersion) to attain good solubility of the relatively nonpolar unexposed resist and poor solubility of the deprotected acidic exposed film. Another approach is to tune the properties of the resist polymer for a given solvent, creating a new optimized resist. We have explored a third methodology to achieve a high contrast solvent developable system without a need to modify resist or solvent. In this report we describe a process that exploits the differences in solubility between ionic and organic materials. In this method an ionic species is introduced into the resist film following post-exposure bake to alter the polarity in such way that the resist contrast can be improved in organic solvent development. We describe processes using pre-rinses and developers containing salts. Lithographic response, characterized using contrast curves and imaging, is presented for a variety of resist platforms. We show evidence for ionic incorporation into the resist film using SIMS, XPS, QCM and FTIR characterization. We demonstrate the practical applicability of this method to 248nm, 193nm, e-beam and EUV exposures.

The impact of develop time and developer concentration was investigated for 193nm resists based on "alternating" polymers of malefic anhydride and norbomene monomers (COMA), prepared by free radical copolymerization. The COMA materials show significant and unique performance dependence on the development process. The development process for COMA materials was found to be a powerful process variable. This paper suggests an explanation for these findings.

Line Edge Roughness (LER) continues to be a serious problem for high resolution 193 nm (ArF), E-beam and EUV resists despite years of research. Changes to the resist formulations, the use of low molecular weight (MW) materials, such as molecular glass resists, and special developers have all been used in attempts to minimize LER. In addition, much recent work has focused on post development processes such as rinses, special coatings and thermal treatments to reduce roughness. However there remains a lack of understanding of the origins of LER. Recently researchers have described interesting results based on the use of in situ high speed AFM to characterize LER during development. 1 In this report we describe a complementary technique wherein the evolution of the roughness of the resist line is measured at different times during the development process. This is accomplished by using a specially designed flow cell 2-5 to control the developer contact time for a series of identically patterned fields and measuring the partially developed patterns with scanning electron microscopy (SEM). We will describe the results for different resist chemistries at 248 nm (KrF). In one aspect of this study, we examine resists that have been patterned at different aerial image contrast (AIC) to systematically probe its effect on LER 6 for a given resist. We intend to extend this work to different exposure systems including 193 nm, EUV and electron-beam.

One of the most promising resist design strategies for the development of high resolution materials for EUV lithography is the PAG anion-bound polymer approach. We have published several reports in the past few years on the structure/property relationships of anion bound PAG resist polymers. This paper will focus on relative performance of novel bound PAG polymers in EUV and electron beam lithographies. We will analyze the performance characteristics of a series of well characterized bound PAG resist polymers using several polymerizable PAG monomers. Due to the limited access to EUV exposure tools, we analyzed the initial lithographic performance with electron beam lithography for improved cycles of learning. We have found several examples of poor correlation between EUV and e-beam (EB) lithography results. We will offer rational for the difference in performance, with the goal of improved insight into both EB and EUV resist design.

Directed self-assembly is an emerging technology that to-date has been primarily driven by research efforts in university and corporate laboratory environments. Through these environments, we have seen many promising demonstrations of forming self-assembled structures with small half pitch (

In this paper, we employ the self-segregating materials approach used in topcoat-free resists for water immersion lithography to extend the performance of topcoat materials for water immersion and to increase the contact angles of organic fluids on topcoat-free resists for high index immersion lithography. By tailoring polymers that segregate to the air and resist interfaces of the topcoat, high contact angle topcoats with relatively low fluorine content are achieved. While graded topcoats may extend the performance and/or reduce the cost of topcoat materials, the large amount of unprotected acidic groups necessary for TMAH development prevent them from achieving the high contact angles and low hysteresis exhibited by topcoat-free resists. Another application of this self-segregating approach is tailoring resist surfaces for high index immersion. Due to the low surface tension and higher viscosities of organic fluids relative to water and their lower contact angles on most surfaces, film pulling cannot be prevented without dramatically reducing wafer scan rates; however, tuning the surface energy of the resist may be important to control stain morphology and facilitate fluid removal from the wafer. By tailoring fluoropolymer additives for high contact angles with second generation organic high index immersion fluids, we show herein that topcoat-free resists can be developed specifically for high index immersion lithography with good contact angles and lithographic imaging performance.

Lactones are almost ubiquitously employed in 193 nm resists to increase the polarity of hydrophobic alicyclic polymers. What else do lactones do in 193 nm resists? We studied the behavior of methacrylate (MA) resists consisting of different protecting groups, hexafluoroalcohols, and norbornane lactone methacrylate (NLM, 2-oxo-3-oxatricyclo[4.2.1.04,8]nonan-5-yl methacrylate). When the protecting group is large [ethylcyclooctyl (ECO) and methyladamantyl (MAd)], thinning of the resist film that occurs in highly exposed areas upon postexposure bake (PEB) is significantly smaller than what is expected from the polymer composition. When the concentration of isopropylhexafluoroalcohol methacrylate (iPrHFAMA) is increased in the ECOMA-NLM polymer, the thinning increases and reaches 100% of theory and the ECOMA-norbornenehexafluoroalcohol methacrylate (NBHFAMA) resist loses quantitative thickness in highly-exposed areas upon PEB at 90 °C. This indicates that small lactones which are more basic than esters can trap deprotection fragments especially when the protecting group is large. Such entrapment was detected by IR spectroscopy and also observed at temperatures as high as 200 °C in thermogravimetric analysis (TGA). Incorporation of lactone appears to decrease the bake temperature sensitivity and the sensitivity of the resist perhaps due to trapping of photochemically generated acids by basic lactone. The lactone ring can be hydrolyzed during aqueous base development but does not seem to affect the dissolution rate, indicating that hydrolysis occurs in aqueous base solution after dissolution. Poly(methacrylic acid-NLM) dissolves as fast as poly(methacrylic acid) in 0.26 N tetramethylammonium hydroxide (TMAH) aqueous solution. While exposed P(ECOMA47-NLM53) resist dissolves in 0.26 N developer at about the same rate as authentically prepared poly(methacrylic acid47-NLM53), the dissolution rate of highly-exposed P(MAdMA44-NLM56) resist is much slower, indicating that the deprotection fragment from the former does not interfere with the development but that from the latter does. When the NLM concentration is increased to 75 %, highly exposed P(ECOMA-NLM) resist dissolves slowly at ca. 600 A/sec and swells significantly, indicating that NLM can be a dissolution inhibitor and swelling enhancer when its concentration is high. Low activation energy protecting groups such as ethylcyclooctyl allows imaging at temperatures as low as 60 °C. However, the temperature dependence of the dose to clear is very large and the chemical contrast is quite small in the low temperature range. Thus, for PEB temperature stability and contrast enhancement, baking 20-30 °C above the lowest practical temperature is recommended.

Immersion lithography has placed a number of additional performance criteria on already stressed resist materials. Much work over the past few years has shown that controlling the water-resist interface is critical to enabling high scan rates (i.e. throughput) while minimizing film pulling and PAG extraction (i.e. defectivity). Protective topcoat polymers were developed to control the aforementioned interfacial properties and emerged as key enablers of 193 nm immersion lithography. Achieving the delicate balance between the low surface energies required for high water contact angles (generally achieved via the incorporation of fluorinated groups) and the base solubility required for topcoat removal is challenging. More recently, additional strategies using fluoropolymer materials to control the water-resist interface have been developed to afford topcoat-free resist systems. In our explorations of fluoroalcohol-based topcoat materials, we have discovered a number of structure-property relationships of which advantage can be taken to tailor the interfacial properties of these fluorinated materials. This paper will address the effect of structure on immersion specific properties such as water contact angle, aqueous base contact angle, and dissolution rate.

The introduction of an immersion fluid in contact with the resist-coated substrate is, from the perspective of the resist material, a significant departure from the conventional lithographic process. The impact of this modification on the lithographic imaging materials is as yet only poorly characterized. We report the results of studies aimed at an improved understanding of how immersion in water during exposure influences the functional properties of films of lithographic materials. We have evaluated the water permeability of candidate immersion topcoat materials; the role of immersion topcoat materials in reducing airborne contamination and water-resist interactions; the impact of water immersion on image blur in chemically amplified resists; and high-resolution imaging of candidate immersion resist materials under conditions of poor aerial image contrast. Analytical techniques such as QCM and reflectance analysis of thin films, DUV interferometric immersion lithography, and trace organic analysis are applied in this work.

Polysilsesquioxane-based 193 nm positive bilayer resists are described. In this design Si for etch resistance is placed in every repeat unit and acid-labile protected and acidic groups (and polar units) are in the side chain, allowing to incorporate each lithographically critical functionality in sufficient quantity. Fluoroalcohol is employed as an acid group instead of carboxylic acid because of its more attractive dissolution properties. Polymers were carefully analyzed by 19F, 13C, and 29Si NMR to determine composition and to quantify residual acetyl, silanol, and Q/T. Hydrogen-bonding between tertiary ester and fluoroalcohol in the polysilsesquioxanes was investigated by FT-IR and the effect of lactone incorporation on the thermal deprotection temperature elucidated. In order to better understand the dissolution behavior of exposed resist films, the silsesquioxane resist polymers were partially (ca. 30%) and fully deprotected in solution with acid and their dissolution kinetics investigated by using a quartz crystal microbalance (QCM). It has been found that the exposed areas of the silsesquioxane resists can have a very fast dissolution rate (Rmax) of >20,000 A/sec (or even >100,000 A/sec). Heating the fully deprotected model polymers to 150°C did not reduce the dissolution rate much, suggesting thermal condensation of silanol end groups is insignificant. Model deprotected polymers containing triphenylsulfonium nonaflate were exposed to 254 nm radiation, baked, and subjected to QCM measurements in order to determine whether or not acid-catalyzed silanol condensation would reduce the dissolution rate. A combination of high dose and high temperature bake resulted in significant reduction of the dissolution rate in the silsesquioxane polymer containing a small trifluoroalcohol. However, the dissolution behavior of the polymer bearing a bulky norbornene hexafluoroalcohol was unaffected by exposure and bake. Chemical and development contrast curves were generated by using a temperature gradient plate and bake temperature effects investigated. While a postapply bake temperature variation from 95 to 130°C did not affect the contrast (chemical and development) and sensitivity, a postexposure bake temperature effect was quite small. The process window of the silsesquioxane bilayer resists was comparable to that of a high performance commercial 193 nm single layer resist for both isolated and nested contact hole imaging, Superior performance of our silsesquioxane resist was demonstrated in patterned etch in comparison with a COMA-based bilayer resist.

In an effort to design our next generation resist materials for sub-100nm lithography, we have introduced the hexafluoroisopropanol (HFA) functionality into the cyclic olefin (CO) polymer structure. It is found that the fluorine-containing HFA group not only helps reduce the 157nm optical density (O.D.) of the polymer and makes it suitable for 157nm application, but also dramatically improves the dissolution properties of the resulting CO polymer. Copolymers with a wide range (20-80%) of norbornene HFA (NBHFA) concentrations show little swelling behavior in aqueous base developer. The dissolution properties of the CO polymer could be further improved by combining the HFA and lactone structures in the CO polymers. This new version of CO polymers maintain a good etch resistance and excellent surface roughness after etch despite the fluorine content. Lithographic evaluation of resists based on these polymers (Cobra 5K) using a 193nm exposure tool (0.75 NA) reveals that Cobra 5K has a low post exposure bake (PEB) sensitivity (

Our primary platform for 157 nm positive resists is built on a copolymer of t-butyl 2-trifluoromethylacrylate (TBTFMA) andnorbornene bearing hexafluoroisopropanol (NBHFA) as an acid group, which is prepared by radical copolymerization. Theradical copolymerization of 2-trifluoromethylacrylic monomers with norbornene derivatives has been found throughreactivity ratio determination and in situ 1 H NMR analysis of kinetics to deviate from the terminal model but to follow thepenultimate model. These copolymers typically contain >50 mol% TBTFMA, are lipophilic, and fail to provide goodimaging due to poor wettability. Blending a homopolymer of NBHFA (optical density (OD)=1.7/ m at 157 nm) into thecopolymers (OD=2.5-2.7/ m) increases the hydrophilicity and reduces OD to 2.2-2.0/ m, providing high resolution images.Another platform we have identified is a copolymer of TBTFMA with vinyl ethers, which can be prepared by using acommon radical initiator. Some of the vinyl ether copolymers are also homogeneously miscible with the NBHFAhomopolymer and thus their OD and aqueous base development can be improved by blending.Keywords: 2-trifluoromethylacrylate, hexafluoroisopropanol, radical copolymerization, reactivity ratios, copolymerizationkinetics, terminal model, penultimate model, dissolution kinetics, quartz crystal microbalance, chemical amplification, 157nm lithography

As 193 nm resist moves into production with minimum feature sizes approaching 100nm, bilayer resist is being evaluated more closely for certain applications. Our polymer design has been evolving to meet tighter outgassing requirements. Optical density, etch resistance and dissolution behavior are other considerations. The protecting group used in our 248 nm bilayer is not useful for 193 nm lithography because of the high optical density contribution from Si-Si linkage. Silicon was incorporated into a COMA platform for the first generation polymer. Maleic anhydride is used to modulate dissolution characteristics. The first generation 193 nm bilayer was optimized to print 120 nm L/S patterns with an attenuated PSM on a 0.6 NA Nikon S302. We will describe next generation platforms that address silicon outgassing concern. The lithographic performance of these resists was evaluated on a 0.6 NA Nikon S302 with a dark field mask. Results for 280nm pitch (1:1 L/S) and 245 nm pitch (105 nm L, 140 nm S) lithography are presented. Also shown is result for a 245 nm pitch (1:1 L/S) and 210 nm pitch (1:1 L/S) on a 0.75 NA ASML PAS 5500/1100. Outgassing data generated at MIT Lincoln Laboratory will be discussed.

The objective of this report will be to clarify the maturity of the current 193 SLR materials. We are going to report on all major platform chemistries, i.e.,(meth) acrylate system, ROMP system, cyclic olefin addition system, cyclic olefin/maleic anhydride system, vinyl ether/maleic anhydride system, and cyclyzed system at the same time. We are going to discuss maturity of each platform from several viewpoints such as polymerization process, physical properties of the resins, lithographic performances of the resists, and process latitude of the resists including etch performances. We are also referring to several critical issues such as etch resistance, surface roughness after etch, line slimming, etc. Three major platform chemistries, (meth)acrylate, COMA, and addition, are selected in order to cover the whole spectra of layer requirements. Those three systems respectively show characteristics lithographic performances.

193nm lithography will be the future technology for sub- 150nm resolution. As the dimensions get smaller, resist thickness is also needed to be reduced for better resolution and wider process window. Single layer 193nm resist, with thickness of less than 500nm, may not be able to satisfy some of the substrate etch requirement. With bilayer resist scheme, the thin resist offers the advantages of high resolution and good process window. The thick underlayer provides the etch resistance required for substrate etching. IBM has developed a silane substituted alternating copolymer based 193nm bilayer resist system and demonstrates sub-120nm resolution using Nikon 0.6NA stepper with Chrome on Glass (COG) mask. Lithographic performance and formulation optimizations of this 193nm bilayer resist as well as underlayer evaluation and some etch study will be discussed.

There is currently tremendous interest in developing 157nm photoresists for imaging applications at 100nm and below. Due to the high VUV absorbance of the polymers used in 248 and 193 photoresists new materials are being investigated for applications at 157nm. In this report the characterization of a number of partially fluorinated polymers based on aromatic backbones will be described. Data on the absorbance, dissolution properties, solvent retention and acid diffusion characteristics of these systems will be presented.

Based on UV measurements at 157nm of in-house fluoropolymers we have selected (alpha) -trifluoromethylacrylate and norbornene bearing a pendant hexafluoroisopropanol group as our building blocks for 157nm resist polymers. Polymers consisting of these repeat units have an optical density/micrometers of 3 or below at 157nm. We have found that the (alpha) -trifluoromethylacrylate derivatives conveniently undergo radical copolymerization with norornenes, which has provided a breakthrough in preparation of our 157nm resist polymers. This approach offers flexibility and versatility because an acidic moiety or acid-labile group can be placed in either acrylate or norbornene repeat unit. Other platforms of interest include all acrylic, all-norbornene, and acrylic-styrenic polymers.

Polycycloolefins prepared by addition polymerization of norbornene derivatives are quite different from hydroxystyrene-based polymers in terms of their interaction with aqueous base. Their dissolution kinetics monitored on a quartz crystal microbalance is not a smooth function of the ratio of the polar to nonpolar functionalities in polymer but abruptly changes from very fast dissolution to massive swelling within a narrow range of composition. The maximum swelling is a function of thickness and the entire film thickness can swell in a few seconds at > 3,000 angstroms/sec or at immeasurably fast rates. The initial concentration of a pendant carboxylic acid in polymer has to be selected to minimize swelling and the concentration of an acid-labile group to induce fast dissolution in the exposed area. Furthermore, swelling which occurs in the partially- exposed regions must be minimized by incorporating a third monomer unit or by adding a dissolution modifying agent (DMA) such as t-butyl cholate. However, the function of DMA which is also acid-labile is quite complex; depending on the matrix polymer composition and its dissolution/swelling behavior, DMA could function as a swelling suppressor or promoter and a carboxylic acid generated by acidolysis of DMA as a dissolution or swelling promoter. Photochemically generated sulfonic acid could also affect the dissolution/swelling behavior. Base hydrolysis of anhydride during development is controlled by the polarity (carboxylic acid concentration) in polymer film, which has been demonstrated in an unequivocal fashion by IR spectroscopy under the condition strongly mimicking the development process and thus could boost development contrast but could hurt performance as well. Thus, incorporation of carboxylic acid in the form of methacrylic acid, for example, in radical copolymerization of norbornene with maleic anhydride must be handled carefully as it would increase the susceptibility of the anhydride hydrolysis and could introduce heterogeneity in the polymer as methacrylic acid is rapidly consumed, producing a terpolymer containing a different molar concentration of norbornene and maleic anhydride (a proof against the commonly believed charge transfer polymerization mechanism).

Understanding and control of molecular weight-dependent properties of 193 nm photoresist polymers has received only limited attention to date. Many physical and thermal properties of polymers in general and novolak- and poly(hydroxystyrene)-based systems in particular are molecular weight dependent. Since these properties markedly influence photoresist behavior, a more detailed understanding of molecular weight effects in 193 nm polymers would be valuable. In this communication, we present a survey of some of the interplays between molecular weight, thermal properties, dissolution behavior, and lithographic performance of methacrylate-based 193 nm polymers. More specifically, this presentation comprises a discussion of discontinuities in thermal properties surrounding the polymer critical entanglement molecular weight in methacrylate 193 nm polymers including the IBM Version 2 and Version 3 platforms. Tg vs. molecular weight curves for both platforms are in good agreement with predictions of the Gibbs-DiMarzio model and reveal that Mcrit is ca. 8,000 for these systems. Lithographic characterization at, below, and above this molecular weight reveals failure due to fraying and line collapse at low molecular weight, failure due to excessive bottom scumming at high molecular weight, and best performance at or near Mcrit.

Mitigation of line edge roughness (LER) remains a significant practical issue for extreme ultraviolet (EUV) resist performance at 22 nm dimensions and below. The authors have applied a suite of experimental characterization techniques and simulation methods to a set of model EUV resists with the aim of strengthening fundamental understanding of the nature and origins of LER. The influence of resist film composition on LER has been evaluated for positive-tone chemically amplified polymer and NORIA molecular glass resists, and has been correlated the effects with surface roughness on resist films exposed at doses comparable to those at the image line edge. The effect of developer type on LER has been characterized using two distinct developer compositions that provide aqueous base positive-tone and organic solvent negative-tone processes. The time evolution of image roughness during pattern development has been visualized using interrupted development in a flow cell configuration that halts the dissolution ...

Because volatile species containing Si and S desorbed from photoresists during exposure to light can irreversibly damage optical elements inside a photolithography tool, accurate quantification of vapor fluxes is essential to evaluate risk. The authors compare measurements using two vapor-collection methods (gas and ion chromatographies) and one solid state analysis method (secondary ion mass spectrometry) to characterize outgassing from two silicon-containing and two all-organic 193nm photoresists during exposure at atmospheric pressure. Results from all three techniques are in good general agreement with the notable exception of Si-containing products. Investigation of the influence of the gas atmosphere above the resist during exposure reveals that gas-surface interactions involving oxygen and perhaps water are a previously unrecognized mechanism for release of Si during exposure of otherwise inert polymers. This result shows that it is essential to take the gas environment inside the photolithographic...

In previous work, we have discussed the issue of real-time control, which is important for the effective application of massively parallel architectures in real-time, or near real-time, signal processing. We first briefly review our work on how to incorporate adaptive programming decisions in systems accommodating massive data parallelism without losing machine efficiency. This involves re-examination of functions to be performed by the software versus those performed by the hardware. Our discussion is based on a Multiple Instruction Multiple Data (MIMD) controller that we have constructed for a Geometric Single Instruction Single Data (GSIMD) array. We then address two more issues facing a GSIMD architecture for its efficient use, especially in vision applications. These are: how to treat the overlap in small neighborhood operations when a large image array is segmented for processing on a smaller GSIMD array, and how to transmit small amounts of information between the array processor and external machines for adaptive signal processing. We describe the architecture of our hardware solutions.

For adequate transparency we have selected hexafluoroisopropanol as an acid group and an α-trifluoromethylacrylic moiety as a repeat unit of our 157 nm resist polymers. The hexafluoroalcohol group is bound to norbornene or styrene. Four platforms are currently available to us: (1) all-acrylic, (2) all-alicyclic, (3) acrylic-alicyclic, and (4) acrylic-aromatic systems. While the all-alicyclic (all-norbornene) polymers are synthesized by transition-metal-initiated addition polymerization, all other polymers involving α-trifluoromethylacrylic monomers are prepared by conventional radical copolymerization. Characterization of the polymers and preliminary lithographic evaluation are reported.