Abstract: The present invention relates to methods of predicting proximity heating in real-time as the writing proceeds enabling beam compensation to be performed in real-time. Particular attention is given to vector scanning in which the pattern of writing does not follow prescribed kinematics, but the writing tends to cluster into cells. A library of standard cells is constructed. As writing of the pattern proceeds, the individual flashes are agglomerated into cells that are compared with standard cells to determine proximity heating in the resist as a function of the distance of the previously written cells from the point of present writing, and the elapsed time since writing a previously written cell. Present writing snaps to a sufficiently coarse space-time grid to limit the computational burden but fine enough the represent variations in temperature over space and time. Further agglomeration of cells into super-cells, super-super-cells, etc. are also described.

Abstract: A charged beam exposing method comprises a step of applying a voltage to a sample to thereby form an acceleration electric field on the sample, a step of accelerating an electron beam emitted from an electron gun and scanning an alignment mark formed on the sample with the electron beam, a step of detecting back-scattered electrons and secondary electrons, generated from the alignment mark, by means of a detector, a step of acquiring the position of the alignment mark based on a signal waveform detected, a step of eliminating or reducing the acceleration electric field by changing the applied voltage to the sample, and a step of exposing a pattern with the electron beam emitted from the electron gun based on information of the position of the alignment mark.

Abstract: Charged-particle-beam microlithography apparatus and methods are disclosed that achieve correction of positioning errors of one or both the reticle stage and wafer stage using a deflector. The deflector is situated in one or both lenses of the projection-optical system of the apparatus. The deflector preferably is electrostatic for rapid responsiveness, and desirably is configured also to correct distortions corresponding to the positioning errors.

Abstract: For lithographic patterning a plurality of identical structures (24) onto a target substrate (14), a template mask (13) is produced which bears a template structure pattern comprising a plurality of identical template structures each consisting of a set of at least one structure element (C) of circular shape. Starting from a primary mask (11) bearing a primary structure pattern consisting of at least one structure element having a circular shape, the production of the template mask is done in at least one lithographic mask structuring step (b, c) wherein in each mask structuring step by means of a broad beam (31) of energetic radiation the mask is illuminated and a structure pattern on the mask (11,12) is imaged onto an intermediate substrate (12a,13a); in these mask structuring steps the pattern image imaged from the structure pattern is moved over the intermediate substrate to a number of different locations.

Abstract: Charged-particle-beam (CPB) microlithography methods and apparatus are disclosed with which large single-shot image-transfer regions (subfields) can be exposed using maximal beam current. Beam current is changed over a selected range to determine a suitable range of beam-spread angles that include the maximum permissible values for average blur, &Dgr;blur, and distortion. Assuming that that range of beam-spread half-angles is between &agr;1 and &agr;2, then the beam current for which &agr;1=&agr;2 is designated as a cutoff beam current. The beam-spread half-angle at that beam current is the optimal beam-spread half-angle. The ratio between the distribution half-angle and the cutoff half-angle is varied, and a determination is made of the distribution half-angle and cutoff half-angle that will accommodate the greatest beam current. Thus, a maximum beam current can be used while maintaining blur and distortion of the projected subfield image within specified values set for them.

Abstract: Aberrations of an imaging system (PL) can be detected in an accurate and reliable way by imaging, by means of the imaging system, a circular phase structure (22) on a photoresist (PR), developing the resist and scanning it with a scanning detection device (SEM) which is coupled to an image processor (IP). The circular phase structure is imaged in a ring structure (25) and each type of aberration, like coma, astigmatism, three-point aberration, etc. causes a specific change in the shape of the inner contour (CI) and the outer contour (CE) of the ring and/or a change in the distance between these contours, so that the aberrations can be detected independently of each other. Each type of aberration is represented by a specific Fourier harmonic (Z-), which is composed of Zernike coefficients (Z-), each representing a specific lower or higher order sub-aberration.

Abstract: On-the-Fly leveling in a lithographic apparatus is conducted using a setpoint derived by filtering the output of the combination of the output of a level sensor and another position sensor (LVDT or IFM). The level sensor may include look-ahead. The filter may be a low pass filter to cut-off level variations of wavelength shorter than the width of the slit during a scanning exposure. The filter may also be selected to reduce cross-talk between tilt movements and horizontal displacements.

Abstract: A lithographic projection apparatus includes a radiation system for providing a projection beam of radiation having a wavelength &lgr;1 smaller than 50 nm; a support structure for supporting patterning structure, the patterning structure serving to pattern the projection beam according to a desired pattern; a substrate table for holding a substrate; and a projection system for projecting the patterned beam onto a target portion of the substrate. The apparatus further includes a radiation sensor which is located so as to be able to receive radiation out of the projection beam, said sensor comprising a radiation-sensitive material which converts incident radiation of wavelength &lgr;1 into secondary radiation; and sensing means capable of detecting said secondary radiation emerging from said layer.

Abstract: A new method is provided for E-beam exposure. A new method is provided for variable shaped E-beam (VSB) and Gaussian laser and E-beam exposure systems. The conventional main pattern is, under the method of the invention involving VSB, surrounded on all sides by a dummy frame whereby the dummy frame limits the beam size of the exposure shots that are adjacent to the main pattern. All patterns that are created in this manner are therefore composites using the same exposure shot. This improves the CD uniformity of the pattern by reducing the shot linearity error for VSB exposure systems. For Gaussian beam exposure systems, the exposure shots are at times located exactly over the exposed figure. Typically, gray level is used to simulate the small figure, this however induces proximity effects. The method of the invention therefore also improves the proximity effect of the Gaussian beam exposure systems.

Abstract: A process for increasing the etch resistance of the upper surface of photoresists by a surface-intensive dose of electron beam radiation. Such imparts increased surface etch resistance to the photoresist without causing as much shrinkage in the bulk of the film. A photographic image is produced by imagewise exposing a photographic composition layer on a substrate to activating energy to produce a latent pattern on the layer. This is followed by developing the photographic layer to thereby remove the nonimage areas thereof and leaving the image areas thereof in the form of a pattern on the substrate. The imaged layer is then overall irradiated to electron beam radiation for the full depth of the layer and then overall irradiated to electron beam radiation one or more additional times at a depth which is less than the full depth of the layer.

Abstract: This invention provides a scattering-angle limiting type of electron-beam exposure system having a mask comprising a scattering region and a limiting aperture which limits the amount of scattered electrons passing through the mask, comprising a first limiting aperture fixed at or near a crossover plane and having a central opening and a closed elongated opening surrounding the central opening; and a second limiting aperture shiftable along an optical axis and having a central opening and a closed elongated opening surrounding the central opening, as well as an electron-beam exposure process using the system. This invention also provides a stencil type of mask suitable for the exposure system and the exposure process. According to this invention, proximity effect correction can be adjusted without significantly reducing a throughput and with excellent linewidth accuracy, especially in a patterning step in manufacturing a semiconductor device.

Abstract: The invention is a charged particle beam exposure method, wherein exposure data having exposure pattern data is generated from pattern data, and a material is exposed accoring with the exposure data; comprising the steps of: (a) generating plural correction areas with respect to the patterns; (b) dividing a long and narrow pattern of the pattern data into a plurality of patterns; (c) determining a pattern area density within the correction areas, and revising the pattern density of the correction area according with surrounding patterns.; (d) determining a main quantity of exposure for each divided pattern according with the highest corrected pattern density; (e) generating supplementary exposure patterns in the correction areas within the divided patterns with a shortage of exposure energy in the case of the main quantity of exposure. An optimum main quantity of exposure is determined for each divided pattern to reduce the number of supplementary exposure patterns.

Abstract: Charged-particle-beam microlithography methods and apparatus are disclosed that employ a segmented reticle and provide high-accuracy pattern transfer even under conditions of drift of the charged particle beam. Beam-drift test patterns are defined on a reticle at the termini of deflection fields at one or both lengthwise ends of certain reticle stripes. Corresponding beam-test marks are situated on or at the wafer. A charged particle beam passing through a beam-test pattern on the reticle is a “detection beam” that is directed to and scanned over the corresponding beam-test mark on the wafer. Before performing actual pattern transfer, the beam-test marks on the wafer are scanned by the detection beam passing through the corresponding beam-drift test patterns on the reticle, and electrons emitted by impingement of the detection beam on the wafer beam-test marks are detected. The positions of the beam-test marks are detected multiple times and the corresponding data is used to measure beam drift.

Abstract: A pattern writing method acquires the area of a pattern segment located in each of a plurality of small regions obtained by dividing a region on which a pattern is to be written, small region by small region, and writes a pattern based on an optimum dose calculated based on this area. This method employs a scheme of shifting pattern segments and averaging the accumulated area, so that even when the pitch of repetitive patterns slightly differs from the side length of each small region in the pitch direction, a peculiar error does not occur, thereby ensuring highly-precise proximity effect correction and contributing to improving the precision of writing an LSI pattern.

Abstract: Apparatus and methods are disclosed for inscribing a pattern on a reticle blank to produce a lithography reticle. As a reticle blank is inscribed using a charged particle beam (e.g., electron beam), some of the incident charged particles pass through the reticle blank and are backscattered from underlying structure (e.g., from a stage used to hold the reticle blank during inscription). These backscattered particles reduce the pattern resolution on the reticle. The present apparatus and methods reduce the number of backscattered particles re-entering the reticle blank, thereby improving pattern resolution.

Abstract: A method and apparatus for emission lithography using a patterned emitter wherein, in the apparatus for emission lithography, a pyroelectric emitter or a ferroelectric emitter is patterned using a mask and it is then heated. Upon heating, electrons are not emitted from that part of the emitter covered by the mask, but are emitted from the exposed part of the emitter not covered by the mask so that the shape of the emitter pattern is projected onto the substrate. To prevent dispersion of emitted electron beams, which are desired to be parallel, the electron beams are controlled using a magnet, a direct current magnetic field generator or a deflection system, thereby achieving an exact one-to-one projection or an exact x-to-one projection of the desired pattern etched on the substrate.

Abstract: A process for decreasing the linewidth of photoresist images which are suitable for use in the production of microelectronic devices such as integrated circuits. A photosensitive composition is coated onto a substrate, exposed to activating energy to decompose the polymer in the imagewise exposed areas; and developed to remove the exposed nonimage areas thus producing a pattern of lines having a linewidth of from about 100 nm to about 200 nm. Then the image areas are controllably irradiated to sufficient electron beam radiation to thereby reduce the linewidth by an amount of from about 5% to about 50%.

Abstract: Methods are disclosed for calculating exposure energy on a sensitive substrate as realized whenever the substrate is exposed with a reticle pattern. The reticle pattern is divided into regions each defining one or more respective pattern elements. The respective pattern element(s) in the various regions are represented by a respective representative figure having an aspect ratio that reflects the aspect ratio of the pattern elements in the region. The representative figure also has an area equal to the collective area(s) of the respective pattern element(s) in the region, and a centroid located at the centroid of the pattern element(s) in the region.

Abstract: Apparatus and methods are disclosed for achieving improved pattern linewidth of a pattern microlithographically transferred to a sensitive substrate using a charged particle beam such as an electron beam. Improved linewidth is achieved even if beam-edge resolution is not optimal. The poorest value of beam-edge resolution of the projection-optical system used to project the reticle pattern onto the substrate is 0.8 to 1.0 times the minimum linewidth of the pattern. A variation in threshold value is maintained at approximately ±1%, allowing linewidth precision to be maintained at a value that is well within a target value of ±10%, even if the beam is 0.9 to 1.0 times the minimum linewidth.

Abstract: This invention provides a charged beam projection mask, a charged beam exposure apparatus, and the like which prevent variations in exposure dose and a positional error of a pattern projected on a wafer, thereby improving a pattern precision. In the charged beam mask, strut portions separating mask pattern regions constituting a stripe in one direction have a width larger than the width of a beam on the mask.

Abstract: An exposure method of sequential beam, contributing to the improvement of alignment accuracy at connecting portion at the end part of an exposure region, as well as pattern dimension accuracy is provided.

Abstract: Charged-particle-beam (CPB) optical systems are disclosed that exhibit reduced eddy currents forming in the beam tube of the system. The eddy currents otherwise would degrade beam-control response time of the system. In an embodiment, the beam tube defines at least one slit in an “eddy-current zone” of the beam tube adjacent an energizable coil of the system, such as a deflector coil. The slit(s) is situated so as to divide the eddy-current zone. The slit(s) extends at least part way through the thickness dimension of the beam tube and can be formed using conventional machine tools, wire cutting, or electrical-discharge machining, or other suitable technique. Compared to an eddy-current zone lacking a slit, the divided eddy-current zones produced by the slit(s) have substantially reduced overall area, thereby reducing eddy current in the beam tube and allowing a corresponding increase in beam-control speed.

Abstract: Reticles and apparatus for performing charged-particle-beam microlithography, and associated methods, are disclosed, in which the pattern to be transferred to a sensitive substrate is divided according to any of various schemes serving to improve throughput and pattern-transfer accuracy. The methods and apparatus are especially useful whenever a divided stencil reticle is used that includes complementary pattern portions.

Abstract: An electron beam drawing mask comprises a substrate for damping an electron beam to a predetermined quantity of electrons while the electron beam passes through the substrate, a metallic film formed on at least one surface of the substrate for interrupting the electron beam, a main pattern constituted by openings bored through the substrate and the metallic film, and an auxiliary pattern formed near the main pattern and constituted by window portions where the metallic film has been removed to expose the substrate.

Abstract: A process for increasing the etch resistance of photoresists, especially positive working 193 nm sensitive photoresists which are suitable for use in the production of microelectronic devices such as integrated circuits. A 193 nm photosensitive composition is coated onto a substrate, exposed to activating energy at a wavelength of 193 nm to decompose the polymer in the imagewise exposed areas; and developed to remove the exposed nonimage areas. Then the image areas are exposed to sufficient electron beam radiation to increase the resistance of the image areas to an etchant.

Abstract: One aspect of the present invention relates to a method of calibrating a measurement instrument that uses an electron beam, involving the steps of providing a conductive photoresist on a semiconductor structure having a conductivity of at least about 0.1 S/cm; exposing and developing the conductive photoresist to provide a patterned conductive photoresist; using the semiconductor structure having the patterned conductive photoresist thereon as a standard for calibration; and calibrating the measurement instrument.

Abstract: A proximity effect correction method for electron beam lithography suitable for use in a raster scan system. The exposure pattern consists of shapes; these shapes are subdivided into edge pixels and interior pixels; the pattern is then modified by uniformly removing a fraction of the interior pixels. The method reduces the backscattered electron background dose, improving the contrast for shapes with fine features, particularly when they are in close proximity to large or densely packed shapes.

Abstract: Polymers comprising recurring units of fluorinated maleic anhydride and/or fluorinated maleimide are novel. Using the polymers, resist compositions featuring low absorption of F2 excimer laser light are obtained.

Abstract: Methods are disclosed for reducing effects of thermal expansion of a sensitive substrate arising during microlithographic exposure of the substrate using a charged particle beam. Thermal expansion ordinarily causes lateral shift of exposure position of dies (chips) on the substrate which tends to reduce the positional accuracy with which images of the dies are formed on the substrate. Generally, regions of the substrate where entire dies are formed are exposed first, followed by regions (especially peripheral regions) exposed with only portions of dies. In addition, the substrate can be mounted on a wafer chuck configured to circulate a heat-transfer gas in contact with the substrate to remove heat from the substrate. In addition, the wafer chuck can be maintained at a constant temperature by circulating a liquid coolant through a conduit in the body of the wafer chuck.

Abstract: A polymer comprising recurring units of formula (1) and having a Mw of 1,000-500,000 is provided.

Abstract: A resist resin comprising a copolymer in which a (meth)acrylic structure having a side chain group decomposable with an acid and a polyorganosilsesquioxane structure represented by formula (1) are present in one molecule or a mixture of polymers in which these structures are each present in different molecules as well as a method of forming a pattern using the resist resin: wherein a reference character or numeral represents the same meaning as recited in the specification. The resist resin of the present invention has high sensitivity to a radiation having a short wavelength of 220 nm or less and is capable of forming a fine pattern of 0.15 &mgr;m or less.

Abstract: First, a mask pattern is defined to a plurality of lattice shaped regions of a uniform dimension. Then, the lattice shaped regions which are adjacent to each other are assigned to different complementary masks. In this manner, the shape of an opening through which electron beams pass is determined so that a displacement caused by a stress acting to each location in the complementary masks is less then a predetermined value.

Abstract: Logic synthesis is conducted for CP apertures 44 using standard cells corresponding to shaping holes 4 used in logic design of a system and placed at first placement positions on the respective CP apertures 44. A CP aperture 44 used for exposure is selected from among the CP apertures for which logic synthesis has been conducted. Second placement positions of the standard cells on a substrate which standard cells correspond to the shaping holes 4 provided on the selected CP aperture 44 and wiring routes the standard cells are calculated.

Abstract: Microlithographic pattern transfer-exposure methods are disclosed by which a pattern for a semiconductor device or the like on the scale of a 16-gigabit DRAM on a 12-inch-diameter substrate can be formed, including such patterns comprising complementary features. The reticle is mounted on a moveable reticle stage and the substrate is mounted on a moveable substrate stage. The reticle pattern is segmented into pattern portions that are transferred onto individual corresponding regions on the substrate. The reticle stage and/or substrate stage can be moved in a step-and-repeat manner and in a continuous-scanning manner during pattern transfer.

Abstract: A process for crosslinking polyacrylate compositions, wherein, by selective irradiation of the pressure-sensitive adhesive composition with electron beams, the polymer is cured only in certain structures and, as a result, structured pressure-sensitive adhesive compositions can be prepared.

Abstract: A polymer comprising recurring units of formula (1) and having a Mw of 1,000-500,000 is provided.

Abstract: A method for improving image fidelity on a resist. The method adjusts the intensity distribution of the electron beam such that the feature size at the edges and the center of a subfield have a same width “w”. This is accomplished by intentionally increasing the incident intensity where the images are small (more pronounced blurring), and intentionally decreasing the incident intensity where the images are large (less pronounced blurring). This can be achieved, for example, by maintaining a cathode temperature profile which increases or decreases radially by an appropriate amount.

Abstract: The specification describes a method and apparatus for electron beam lithography wherein a Wehnelt electron gun is modified to improve the uniformity of the electron beam. A mesh grid is applied to the Wehnelt aperture and the mesh grid functions as a multiple secondary emitter to produce a uniform beam flux over a wide area. The grid voltage of the modified gun is substantially lower than in a conventional Wehnelt gun, i.e. less than 100 volts, which can be switched conveniently and economically using semiconductor drive circuits.

Abstract: The present invention relates to electron beam lithography, and is directed to a method of compensating for pattern dimension variation caused by a re-scattered electron beam when an electron beam resist is exposed to the electron beam. The method of compensating for pattern dimension variation caused by a re-scattered electron beam comprises the steps of: dividing original exposure pattens into square sections; obtaining a dose of supplemental exposure to the re-scattered electron beam; and compensation-exposing the electron beam resist so that the supplemental exposure dose may be the same for all sections. According to the present invention, the pattern dimension variation can be compensated for a re-scattering effect of the electron beam, thereby uniformly forming a fine pattern width of a more highly-integrated circuit.

Abstract: Charged-particle-beam (CPB) microlithography apparatus and methods are disclosed that employ a segmented reticle in which the pattern defined by the reticle is divided into multiple subfields, and each subfield is subdivided into multiple subregions each constituting a respective “group” of subregions. During exposure of the pattern from the reticle to a sensitive substrate using a charged particle beam, a charged-particle illumination beam is directed in sequence to each of the groups. At each group, the illumination beam is directed to expose the respective subregions in the group in a predetermined order before directing the illumination beam to a subsequent group. Direction of the illumination from one group to the next can be performed using a first deflector, and direction of the illumination beam from one subregion to the next in a group can be performed using a second deflector.

Abstract: Charged-particle-beam pattern-transfer methods, apparatus, and masks are disclosed that reduce the effects of resist-heating, avoid the so-called stencil problem, and exhibit high throughput. A circuit pattern is divided into low-resolution and high-resolution features that are defined by respective mask patterns in different areas of a mask or on different masks. The respective mask patterns are projected overlappingly onto the substrate. In another embodiment, a mask pattern defines low-resolution circuit features and a portion of high-resolution features. A second mask pattern defines a substantial portion of the high-resolution circuit features. The first and second mask patterns are projected onto the substrate with the charged-particle beam at first and second doses. The first dose, corresponding to the low-resolution circuit features, is larger than the second dose, and the first and second doses are independently selectable.

Abstract: Polymers comprising recurring units of an acrylic derivative of fluorinated backbone represented by formula (1) are novel.

Abstract: An EUV radiation source unit (10) for use in a lithographic projection apparatus to illuminate a mask pattern (22) which is to be projected on a substrate (W) comprises an electron source (12) and a medium in which the electrons of the source generate EUV Cherenkov radiation (PB). The wavelengths of the Cherenkov radiation and the multilayer structure of the mirrors (31-34) of the projection system (30) are adapted to each other, so that these mirrors show a maximum reflectivity. The medium forms part of the mask (MA) so that a mirror condenser system is no longer needed. In this way, an efficient transmission of radiation (PB) from the source to the substrate is obtained.

Abstract: Charged-particle-beam (CPB) optical systems, and CPB microlithography apparatus including CPB optical systems, are disclosed that include a “shaping aperture” that absorbs a very low percentage of incident charged particles and hence does not experience excessive temperature increases due to bombardment by and absorption of incident charged particles. Nevertheless, the shaping apertures are effective for trimming and shaping a charged particle beam to produce a downstream-propagating beam having a desired transverse profile. The aperture opening in the shaping aperture is defined in a conductive thin-film membrane. The membrane thickness is configured to cause charged particles incident on the membrane to experience scattering (e.g., forward-scattering). CPB optical systems including the shaping aperture also include a “screening aperture” downstream of the shaping aperture to block (absorb) scattered charged particles.

Abstract: Methods and devices are provided for performing adjustments of illumination uniformity obtained from a charged-particle illumination-optical system as used, e.g., in a charged-particle-beam (CPB) microlithography apparatus. The adjustments are based on measurements of illumination-beam current density. The device includes an aperture plate (desirably a silicon membrane), defining a tiny measurement aperture (desirably about 1 &mgr;m diameter), mounted on the reticle stage at the reticle plane. The illumination beam is scanned over the aperture. Charged particles of the beam passing through the aperture are directed to a beam-current detector on or at the substrate stage. The membrane desirably has a thickness of about 1 to 3 &mgr;m. The measurement aperture allows the distribution of current density of the illumination beam to be measured highly accurately.

Abstract: The present invention relates to electron beam lithography, and is directed to a method of compensating for pattern dimension variation caused by a re-scattered electron beam when an electron beam resist is exposed to the electron beam. The method of compensating for pattern dimension variation caused by a re-scattered electron beam comprises the steps of: dividing original exposure pattens into square sections; obtaining a dose of supplemental exposure to the re-scattered electron beam; and compensation-exposing the electron beam resist so that the supplemental exposure dose may be the same for all sections. According to the present invention, the pattern dimension variation can be compensated for a re-scattering effect of the electron beam, thereby uniformly forming a fine pattern width of a more highly-integrated circuit.

Abstract: Methods are disclosed for reducing distortions, differences in focal point-positions, and astigmatic blurring of a pattern defined on a reticle and projected onto a sensitive substrate using a charged particle beam. The methods reduce variations in the distribution of beam current as projected onto the substrate. To such end, a charged particle beam passing through pattern features as defined on the reticle is projected onto a region on the substrate. The reticle is provided with multiple “micro features” each having a size less than the resolution limit of the projection-optical system. The micro features can be provided on a portion of the reticle having a low feature density.

Abstract: A hybrid exposure strategy for pattern generation uses wide field raster scan deflection and a uniformly moving stage to expose long stripes. Periodic analog wide field magnetic scan is augmented by a high speed electrostatic retrograde scan to keep the beam essentially stationary during exposure of rectangular flash fields and/or Gaussian beams. In this manner a staircase deflection trajectory is created for the beam. The position and dose data for each flash is derived from a rasterized data format using a decoder device.

Abstract: A non-lithographic process for producing nanoscale features on a substrate is presented. The process involves applying to and reacting a first difunctional molecule with the surface of a substrate. A second difunctional molecule is applied and reacted with unreacted functional groups from the first difunctional molecule to form a patterned layer on the surface of a substrate. Selective application of the difunctional molecules is accomplished by using a nanoscale delivery device.

Abstract: A positive-working electron beam or X-ray resist composition comprising: (a) a compound capable of generating an acid by irradiation of an electron beam or X-ray; (b) a resin containing a group which is decomposable by action of an acid to increase solubility in an alkali developing solution or (e) a resin insoluble in water and soluble in the alkali developing solution; and (c) a fluorine and/or silicon surfactant, the compound capable of generating an acid by irradiation of an electron beam or X-ray being a compound which generates benzenesulfonic acid, naphthalenesulfonic acid or anthracenesulfonic acid which is substituted by at least one fluorine atom and/or at least one group containing a fluorine atom.