DE102011081247A1 - Exposure system and method for the structured exposure of a photosensitive layer - Google Patents

Abstract

The invention relates to an exposure system (5) for the structured exposure of a photosensitive layer (1), comprising: generating means (7) for producing a plurality of in particular parallel exposure beams (3), each exposure beam (3) forming a portion of the photosensitive layer (1 ), a movement device (13) for scanning, in particular, the exposure beams (3) over or relative to the respectively assigned subarea, and a near-field optical system (15) arranged in front of the photosensitive layer (1) for converting a respective exposure beam ( 3) in an evanescent wave (17) for generating a light spot on the photosensitive layer (1) whose extent is smaller than the extent of a respective exposure beam (3) in front of the near-field optical system (15). The invention also relates to an associated exposure method.

Description

Background of the invention

The invention relates to an exposure system for the structured exposure of a photosensitive layer and to an associated exposure method.

Exposure systems for microlithography can imprint structures with high precision in a photosensitive layer formed on a substrate. Such exposure systems generally consist of a light source, a light emitted by the light source to illuminating light processing illumination system, an object to be projected, generally called reticle or mask, and a projection lens, which images an object field on an image field. The mask or at least a part of the mask is located in the object field and the substrate (also referred to below as wafer) or at least part of the substrate is located in the image field of the projection objective.

If the mask is located completely in the region of the object field and the wafer is exposed without a relative movement of the wafer and the image field, the lithography system is generally referred to as a wafer stepper. If only a part of the mask is located in the region of the object field and the wafer is exposed during a relative movement of the wafer and the image field, the lithography system is generally referred to as a wafer scanner. The spatial dimension defined by the relative movement of reticle and wafer is generally referred to as scan direction. An exposure apparatus for near-field lithography, which is based on the principle of step-and-repeat exposure, is in the article "Near-Field Lithography as Prototype Nano-Fabrication Tool", Microelectronic Engineering 84 (2007) 705-710 by Yasuhisa Inao et al. described.

In addition to exposure systems in which a fixed structure is mapped on a mask on a photosensitive layer, there are also exposure systems based on the principle of raster scanning and in which a plurality of typically parallel, spaced-apart exposure beams are generated in Dependence on a structure to be generated on the photosensitive layer to be modulated. In this case, the photosensitive layer can be displaced transversely to the exposure beams, so that the entire surface to be exposed can be patterned. As exposure radiation in this case type safe way electron beam is used, as z. B. in the in the US 7425713 B2 described system is shown.

Object of the invention

The object of the invention is to specify exposure systems and associated exposure methods which enable a structured exposure of a photosensitive substrate with high resolution.

Subject of the invention

According to a first aspect, the invention relates to an exposure system for structured exposure of a photosensitive layer, comprising: generating means for generating a plurality of in particular parallel exposure beams, each exposure beam being associated with a portion of the photosensitive layer, moving means for scanning the exposure beams in particular over the camera or relative to the respective associated subarea, and a near field optics arranged in front of the photosensitive layer for converting a respective exposure beam into an evanescent wave for generating a light spot on the photosensitive layer whose extent is smaller than the extent of a respective exposure beam in front of the near field optics.

In such an exposure apparatus, the area of the photosensitive layer or the wafer to be exposed is subdivided into a plurality of subregions in which the exposure takes place simultaneously with a respective exposure beam, ie. H. Each subarea is assigned an exposure beam. The exposure beams typically start from a two-dimensional grid and are parallel, so that a pattern generated by activating or deactivating the individual exposure beams is transferred to the photosensitive layer, i. H. a structure to be formed on the photosensitive layer is determined by the pattern of exposure beams.

The operation of transferring the pattern of the exposure beams to the photosensitive layer is performed a plurality of times, and between successive transfer steps, the exposure beams as a whole are shifted with respect to the photosensitive layer, so that a respective exposure beam successively reaches each location in the respective area and onto them Way the entire surface to be exposed is microstructured. It is understood that for this purpose the exposure beams are manipulated independently of each other, i. H. in particular independently switched on or off.

The extent of the subregions on the photosensitive layer is more typical here On the order of magnitude (ie about 1 to 10 times) of a diffraction disk (Airy disk) which the respective exposure beam produces on the photosensitive layer. The size or the diameter of the diffraction disk is determined by the smallest aperture diameter of the exposure system (or a projection objective used there), since this limits the resolution of the exposure system. In the context of this invention, techniques are described which make it possible to carry out the structuring of the photosensitive layer with an increased resolution compared with this so-called diffraction limit, ie techniques are described in which only part of the extent of a respective diffraction disk contributes to the exposure.

According to a first aspect of the invention, this is achieved in that a near-field optical system is arranged immediately in front of the photosensitive layer, which makes it possible to reduce the expansion of the exposure beams, so that a light spot is generated on the photosensitive substrate whose extent or Diameter is significantly less than the extension of the diffraction disk, which has an entering into the near field optical exposure beam.

In one embodiment, a side of the near field optics facing the photosensitive layer is spaced apart from the photosensitive layer by less than the wavelength of the exposure beams. This is favorable because the intensity of the evanescent wave formed at the near-field optics decreases exponentially with the distance from the place of generation of the evanescent wave. The wavelength of the exposure radiation used can be in the near UV range, z. At 193 nm. But it is also possible to use exposure radiation whose wavelength is in the visible wavelength range. The use of an immersion fluid is possible.

If the photosensitive layer (resist) is sufficiently robust, the near field optics may possibly at least partially touch the photosensitive layer. A dose and / or focus control (see below) may also be provided in order to take into account the strong distance dependence of the intensity of the exposure beams coupled into the near field, since this may possibly lead to an inhomogeneous illumination of the photosensitive layer.

In a further embodiment, the exposure system additionally comprises a detector device for detecting the intensity of the exposure beams reflected at the near-field optical system. The intensity of the reflected light can be measured channel by channel, i.e. by a suitable spatially resolving detector device (CCD camera or the like). H. individually for each exposure beam. In this way, typically the energy input of a respective exposure beam or the evanescent wave generated thereby in the photosensitive layer can be measured indirectly. The less energy is introduced into the photosensitive layer, the more energy is reflected and vice versa. By coupling the detector device to the light-generating device (or a filter device, see below), the intensity of the individual exposure beams can be adjusted independently of each other so that the photosensitive layer is exposed (nearly) uniformly.

In a further development, the exposure system comprises a distance determination device for determining a distance and preferably a tilt between the near-field optical system and the photosensitive layer, in particular based on the detected intensity. On the basis of the channel-detected intensity can be concluded that the energy introduced into the photosensitive layer and thus locally to the distance between the near field optics and the photosensitive layer. By determining the distance between the near-field optical system and the photosensitive layer at a plurality of locations, it is additionally possible to determine the orientation or the tilting of the near-field optical system relative to the photosensitive layer. If necessary, the tilt can be corrected by manipulators provided at the near field optics (eg in the form of piezo actuators). Manipulators may also be used to adjust the distance between the near-field optic and the photosensitive layer to a desired target value (focus control). If appropriate, the distance determination device can also be designed to carry out a capacitive or ellipsometric determination of the distance between the near-field optical system and the photosensitive substrate.

In a further embodiment, the exposure system comprises a filter device arranged in front of the near-field optical system for influencing the intensity and / or the polarization of a respective exposure beam. The filter device can, for. B. be designed as a gray filter or as a polarizing filter, which has a z. B. effected by applying a voltage location-dependent variable transmission or influencing the polarization. If the distance between the near-field optical system and the photosensitive layer varies in a location-dependent manner, the resulting inhomogeneity of the light distribution on the photosensitive layer can be compensated by a suitable influencing of the intensity distribution in front of the near-field optical system. The individual exposure beams can here z. B. be suitably modulated by gray or polarizing filter in intensity.

In a further development, the lighting system additionally comprises a control device for controlling the filter device as a function of the intensity detected by means of the detector device. The control device can be used to adjust the intensity and the phase (and optionally also the exposure time) of the individual exposure beams as a function of the measured or detected variables, so that they are applied to the photosensitive layer or when hitting the near field optics have a desired property. In particular, the control device can also be used to minimize the intensity differences between the individual exposure beams incident on the photosensitive layer, ie to produce an intensity distribution on the photosensitive layer which is as uniform as possible.

In one embodiment, the near-field optical system has a shadow mask with a plurality of passage openings whose diameter is preferably smaller than the wavelength of the exposure beams. One possibility for increasing the resolution is the use of a shadow mask, which is transparent only within the passage openings for the exposure beams. The diameter of the passage openings is in this case usually smaller than the diameter of the diffraction disks of the exposure beams, d. H. the extent of the passage openings transversely to the light propagation direction of the exposure beams is smaller than the wavelength of the exposure radiation. The distance between the shadow mask and the photosensitive layer is usually smaller than the wavelength of the exposure radiation (see above), so that the exposure radiation as a so-called evanescent wave (corresponding to the quantum mechanical tunnel effect) in the photosensitive layer at the location of the passage opening enter and the photosensitive layer can expose ("contactless nanoimprint").

In a development, the shadow mask has a substrate that is transparent to the exposure beams and a barrier layer facing the photosensitive substrate, on which the plurality of passage openings is formed. The barrier layer with the passage openings is applied in this case on the carrier serving as a transparent substrate. As a barrier layer, for example, in the use of radiation in the near UV range, for. B. at about 193 nm, serve a chromium layer, which is no longer permeable at a wavelength of about 50-80 nm for exposure beams at this wavelength.

In a development, the transparent substrate is structured on its side facing the photosensitive layer and in particular has tapered structures. The structuring of the transparent substrate serves as a micro-optic, with pointed, cone-shaped structures in particular having proven to be particularly favorable. The passage openings in the barrier layer are in this case at the cone tips, which are typically arranged at a distance from the photosensitive layer, which is smaller than the wavelength of the exposure radiation.

In another embodiment, the light propagation direction of the exposure beams is at an angle to the near-field optic (and hence the photosensitive layer), the near field optic having a dielectric substrate having a plurality of tapered metallic structures embedded in the dielectric substrate. In this case, the incident exposure radiation serves to excite surface plasmons in the pointed metallic structures. These induce an alternating electric field within the structures, which emerges at the tips as a maximum compression as an evanescent wave and is attenuated exponentially as a function of the distance to the photosensitive layer. With a small distance between each tip and the photosensitive layer (typically smaller than the wavelength of the exposure beams used), the intensity of the evanescent wave will suffice to expose the photosensitive layer in a very small area around the tip.

In order to excite the surface plasmons in the metallic tips, it is necessary to use p-polarized illumination radiation, ie, the direction of light propagation must be at an angle to the near-field optics so that one plane of incidence (and hence p-polarization) is even defined. In order to excite the surface plasmons, in addition, the wave number of the exposure radiation used must be adapted to the plasma frequency of the metal, which is possible via the dielectric, cf. especially " http://en.wikipedia.org/wiki/Surface_Plasmon "For more details on the generation of surface plasmons. When using exposure beams having a wavelength of about 193 nm, in particular aluminum can serve as plasmon source here. In this case, if the mechanical resistance of the photosensitive layer permits, the metallic tips may also be in direct contact with the photosensitive layer.

In a further embodiment, the exposure system comprises a super-lens for imaging evanescent waves emerging from the near field optics onto the photosensitive substrate. As a so-called super-lens, an arrangement is called, which makes it possible to transport evanescent waves (almost) unattenuated and possibly even to reinforce. This is possible because the super lens has a negative refractive index for the wavelength of the exposure radiation.

Even with the super lens surface plasmons are excited. In the simplest case, the superliner here has a layer stack comprising a first dielectric, a metallic layer and a second dielectric. The thicknesses of the (planar) layers are typically on the order of the wavelength of the exposure radiation. Such a super lens, in which silver serves as a metallic layer, is in the article "Super-resolution near-field lithography using planar silver lenses" by David OS Melville et al. (Invited Poster, MNE-2005 ID 00709, "http://www.mne05.org/3-c_01.pdf") shown. At wavelengths in the near UV range, eg. B. by about 193 nm, the use of an aluminum layer has been found to be favorable. As a dielectric quartz glass can be used at such wavelengths. The super lens may be integrally formed with the near field optic.

A further aspect of the invention relates to an exposure apparatus, comprising: a substrate having a photosensitive layer, generating means for producing a plurality of in particular parallel exposure beams having (at least) one illumination wavelength, each exposure beam being associated with a portion of the photosensitive layer and the generator being formed To generate exposure beams having a maximum intensity which is above an intensity threshold value for transferring the photosensitive layer from a second state to a first state, a movement device for scanning the exposure beams in particular via the relative to the respectively associated partial region, and a Excitation light source for generating excitation radiation having (at least one) excitation wavelength for transferring the photosensitive layer from the first state to the second state.

In this aspect of the invention, it is utilized to increase the resolution that the photosensitive layer changes at an intensity threshold between the second and the first state, which is below the maximum intensity of the exposure beam, which is typically achieved in the center of a respective exposure beam. In the case of a reversible state transition, it can thereby be achieved that the photosensitive layer is converted from the second state into the first state, except in a partial area provided for structuring, which represents a subregion of the (diffraction-limited) region which covers an exposure beam incident on the photosensitive layer is, so that the structuring can be done only in the space provided for this purpose.

By means of the excitation light source, the photosensitive layer can be converted from the first state to the second state. The exposure beams, on the other hand, have the opposite effect, i. H. they serve to transfer the photosensitive layer from the second to the first state. The excitation can take place before or during the exposure. It is understood that both the excitation radiation and the exposure radiation need not only have a single wavelength, but may possibly cover a respective wavelength range. Since both the excitation light source and the light-generating device usually have a laser light source, but the radiation generated by these to a good approximation only a single wavelength.

In one embodiment, the transition from the first state to the second state is reversible and the photosensitive layer can only be converted into a permanently changed chemical state in the second state. Since the transition between the two states is reversible, the excitation of the photosensitive layer can take place before the exposure, wherein the photosensitive layer can in particular be homogeneously charged with the excitation radiation. In this case, for example, an exposure method may be performed as described in US Pat US 2006/0044985 A1 which is incorporated herein by reference in its entirety. In the method described there, the photosensitive layer is converted after the excitation by means of exposure radiation from the second state to the first state, wherein a narrow range is recessed, that is not hit by the exposure radiation or the intensity of the exposure radiation is minimal there so that the photosensitive layer remains there in the second state, since the intensity of the exposure rays remains there below the intensity threshold.

In a further embodiment, the subareas to which the respective exposure beams are assigned at least partially overlap. In order to obtain an intensity which is safely above the intensity threshold outside the narrow range of minimum intensity described above, it is favorable if adjacent subregions, to which an exposure beam is assigned in each case, partially overlap, so that the intensity distributions also overlap overlap adjacent exposure beams in their outer areas and superimpose there to a total intensity, which is above the intensity threshold.

In a development, the exposure system has a fixing light source for transferring the photosensitive layer from the second state to the permanently modified chemical State on. In this case, the photosensitive layer can be converted into the permanently changed chemical state by the fixing light source in the region in which it is in the second state, and structured in this way. Once a region of the photosensitive layer has been converted into the permanently altered chemical state, it no longer reacts to the excitation radiation or the exposure beams of subsequent exposures.

In a further embodiment, the excitation light source is designed to generate excitation radiation having a location-dependent varying intensity profile on the photosensitive layer, the excitation radiation preferably having a maximum intensity between two exposure beams impinging on the photosensitive substrate. By generating a location-dependent intensity profile of the excitation radiation, the exposure beams can be superimposed on the excitation radiation such that a maximum of the intensity forms in a narrowly limited area corresponding to an STED ("Stimulated Emission Depletion") microscope, which forms the photosensitive layer in the first condition transferred.

In a further embodiment, the transition from the second state to the first state is irreversible, i. H. the second state already represents a state with permanently changed chemical properties. A photosensitive layer having such properties can be used in particular in the case of the above-described simultaneous use of excitation radiation and exposure radiation. In this case, if the combined intensity of excitation and exposure radiation is above the intensity threshold, the photosensitive layer in the associated region becomes the first, permanently altered, chemical state.

Alternatively, it may be possible to completely dispense with the use of excitation radiation, i. E. H. a photosensitive layer (resist) in which the intensity threshold is so high (e.g., at 80% or 90% of the maximum intensity of the exposure rays) that the photosensitive layer is only in a small subrange of the intensity distribution can be used irreversibly transferred from the second to the first state, the z. B. at 30% or less of the area covered by a respective exposure beam. In this case, the resist in the area in which the intensity threshold was not exceeded should "forget" the exposure as quickly as possible, ie. H. A so-called Alzheimer's Resist should be used. Such resists are z. B. used for rewritable DVDs and z. B. be formed as a chalcogenide, in which the transition between the two states in particular takes place thermally between an amorphous and a crystalline phase.

In other words, the surface area to be patterned may either be in the center of a respective exposure beam when the intensity threshold is exceeded, or alternatively at the center of a region where (almost) no exposure radiation strikes the photosensitive layer, i , H. in the range of a minimum of the intensity distribution on the photosensitive layer. In order to make the respective surface area as small as possible and thus the resolution as large as possible, a considerable maximum intensity of the exposure radiation may be necessary.

In another embodiment, the photosensitive layer comprises a switchable organic dye or a switchable chalcogenide. Switchable organic dyes have dye molecules which are switchable by means of light from a second state to a first state (and vice versa). As discussed above, in chalcogenides, the transition between the two states typically occurs by thermal excitation between an amorphous and a crystalline phase.

In a development, the second state of the switchable organic dye can be converted by stimulated emission into the first state of the switchable organic dye. As in STED microscopy, the dye can be converted from a first energetically lower state into a second, energetically higher state by means of excitation radiation and returned to the first state by stimulated emission with the aid of exposure beams in a suitable wavelength range , Typically, the wavelengths needed to excite the dye into the second state and to stimulate stimulated emission to the ground state differ.

The first and second states may also be different structural isomeric states of the switchable organic dye, for example, two isomeric states representing a cis-trans transition of the respective dye molecules, as in, for example, the above US 2006/0044985 A1 is described. While the dye molecules in the first state (eg trans state) can be converted into a permanently changed chemical state by irradiation with fixation light, this is not possible in the second state (eg cis state).

In addition to the use of fluorescent dyes in which stimulated emission Of course, light-sensitive layers with other types of (reversible) state transitions in the exposure system can be used, for example, a transition from an energetically excited state to the ground state. For example, the above-mentioned chalcogenides in which the transition between amorphous and crystalline phase is thermal (eg, excited by an exposure pulse).

In a further embodiment, the generating device has a raster arrangement with a plurality of switchable raster elements for switching on or off a respective exposure beam as a function of a structure to be produced on the photosensitive layer. With the aid of the grid arrangement, an activated, d. H. switched grid elements corresponding pattern of light spots are generated.

In a development, the raster elements of the raster arrangement are designed as switchable diaphragms for a respective exposure beam. The raster arrangement transmits in this case exposure radiation only in those areas in which the raster elements are activated, d. H. in which these do not act as screens. The illumination radiation, however, is blocked in the areas where the grid elements are turned off.

In one development, the grid arrangement is designed as an LCD array, as a laser diode array or as an OLED array. In the first case, a lighting device is needed, which illuminates the LCD array on its side facing away from the photosensitive substrate. When using a laser diode array or an OLED array, each raster element has its own light source, which can be activated individually to produce a respective exposure beam. There are both LCD arrays and laser diode or OLED arrays available in the market, in which the Raserelemente are sufficiently small to achieve a very high resolution. In particular, the switching times of commercially available OLED arrays are sufficiently small to ensure a high throughput in the exposure.

In an alternative embodiment, the raster elements are designed as switchable reflectors for a respective exposure beam. The raster elements can in this case deflect the exposure radiation onto the photosensitive layer in a first, active switching position, whereas in a second, deactivated switching position they do not deflect the exposure radiation onto the photosensitive layer but into another spatial area.

In a further development, the grid arrangement is designed as a micro-mirror array (MMA). The raster elements of MMAs are very small and have sufficiently short switching times of the switchable reflectors to allow a high throughput in the exposure.

In a further embodiment, the movement device has at least one displacement unit for displacing the grid arrangement relative to the photosensitive layer, preferably in synchronism with the near-field optical system. In order to shift the exposure beams in the respective partial areas, it is favorable to displace the grid arrangement in a plane parallel to the photosensitive layer. For this purpose, the movement device can have two linear displacement units which displace the grid arrangement in two directions which are preferably perpendicular to one another in this plane. In this way, scanning of the partial area of the photosensitive layer can take place in order to structure it over the entire area. It is understood that alternatively, if necessary, the grid arrangement remain stationary and the photosensitive layer or the substrate can be moved. Of course, a simultaneous, possibly opposite movement of substrate and grid arrangement is possible.

In a further embodiment, the generating device has a lighting device for, in particular, homogeneous illumination of the grid arrangement. In this case, the grid arrangement is struck completely by the illumination radiation and the individual exposure beams are generated on the grid elements of the grid arrangement, which are switched to an active state, while they are not transmitted to the photosensitive layer by the other (deactivated) grid elements.

In a further embodiment, the exposure system has an objective for reducing the size of the raster arrangement to the photosensitive layer or to the near-field optical system. The shrinking image, z. By a factor of 10, increases the resolution in the exposure of the photosensitive layer. If the exposure system has near-field optics, the image typically takes place on this or on the side facing away from the photosensitive layer, ie. H. this forms the image plane of the lens.

The invention also relates to a method for the structured exposure of a photosensitive layer which is associated with the first aspect, comprising: generating a plurality of in particular parallel exposure beams, each exposure beam being associated with a partial area of the photosensitive layer; Exposing beams above and relative to the respective associated portion, and arranging near field optics in front of the photosensitive layer for converting a respective exposure beam into an evanescent wave for generating a light spot on the photosensitive layer whose extent is smaller than the extent of the exposure beam before Near-field optics.

As described above, the exposure of the photosensitive layer is parallelized as much as possible by simultaneously emitting a plurality of exposing beams to the layer to be exposed, each of which has a partial area incident on the photosensitive layer which is on the order of a diffraction disk. The near field optics serve to increase the resolution beyond the diffraction limit, ie. H. the exposure beam is reduced to a light spot whose extent z. B. may be an order of magnitude below the diffraction limit, so that the structuring of the entire photosensitive layer, the exposure beams are in particular scanned over the photosensitive layer or the corresponding portion.

A method for the structured exposure of a photosensitive layer assigned to the second aspect comprises: generating a plurality of in particular parallel exposure beams, each exposure beam being associated with a partial area of the photosensitive layer, and moving the exposure beams over the respective associated partial area, the exposure beams be generated with a maximum intensity which is greater than the intensity threshold for transferring the photosensitive layer from a second state to a first state, exciting the photosensitive layer with excitation radiation to transfer the photosensitive layer from the first state to the second state, and recycling Photosensitive layer from the second state to the first state in a non-structuring intended area.

As described above, in the second aspect, a photosensitive layer having a defined intensity switching threshold is used, so that, with a suitable choice of the intensity of the exposure beams, the resolution can be increased beyond the diffraction limit. In this case, the photosensitive layer can be converted reversibly from the first state into the second state by the excitation radiation and returned to the first state by means of the exposure beams in an area not intended for structuring. Only in the region to be structured, in which the exposure radiation has a minimum (or a maximum, see above), the photosensitive layer is not converted to the first state and can therefore z. B. be converted using fixed radiation in a permanently chemically altered state.

Further features and advantages of the invention will become apparent from the following description of embodiments of the invention, with reference to the figures of the drawing, which show details essential to the invention, and from the claims. The individual features can be realized individually for themselves or for several in any combination in a variant of the invention.

drawing

Embodiments are illustrated in the schematic drawing and will be explained in the following description. It shows

1 a detail of a photosensitive layer having a plurality of partial areas, to each of which an exposure beam is assigned,

2 a schematic representation of an exposure system for the simultaneous generation of a plurality of exposure beams and with a near field optics.

3a D schematic representations of different embodiments of a near-field optics,

4 a schematic representation of an exposure system with a grid arrangement in the form of an LCD array,

5 a schematic representation of an exposure system with a grid arrangement in the form of a light-emitting diode array,

6 a schematic representation of a location-dependent intensity distribution of the exposure radiation and an intensity threshold of the photosensitive layer,

7 a representation analog 6 with an intensity minimum below the intensity threshold,

8th a schematic representation of a generated by superimposition of the exposure radiation with excitation radiation intensity distribution,

9 a schematic representation of an exposure system with an excitation light source and a Fixierlichtquelle and a LED array, and

10 a schematic representation analog 9 with an OLED array and a lighting system.

In 1 is schematically a detail of a photosensitive layer 1 shown having a plurality of quadratic subareas 2a Each having an exposure beam 3 assigned. As in 1 can be seen, lies the extent of a particular subarea 2a -H in the order of the extent represented by a dashed circle 4 of a respective exposure beam 3 , ie in the present case about ten times as large as the extent 4 an exposure beam 3 , The photosensitive layer 1 comes with several exposure beams 3 simultaneously exposed, depending on one on the photosensitive substrate 1 to be generated structure individually on or off, as described below with reference to 2 is explained.

2 shows an exposure system 5 for exposure of the photosensitive layer 1 on a substrate 6 (Wafer) is attached. The exposure system 5 has a light-generating device 7 on. This includes a light source 7a in the form of a laser for generating exposure radiation having a wavelength of e.g. B. 193 nm or 157 nm. The light source 7a serves the full-surface illumination of a grid arrangement 8th , which is designed as a micro-mirror array (MMA). The micro-mirror array has a plurality of individually controllable raster elements 9 in the form of mirror elements. The micro-mirror array 8th can hereby z. B. a matrix arrangement of about 4000 × 2000 raster elements 9 having a raster element 9 ('individual mirror'), eg B. may have an area of about 16 microns × 16 microns. MMAs available on the market have switching frequencies in the range of about 5 kHz to a single mirror 9 from an (active) basic position, in which the individual mirror 9 in a plane 10 parallel to the plane of the photosensitive layer 1 is arranged to move into a tilted position in 2 to simplify only a single mirror 9 is shown. The throughput of the wafers to be exposed 6 is at a switching frequency of about 5 kHz at about 100 wafers per hour.

Because the individual mirror 9 of the MMA 8th are separated from each other by non-reflective areas, arises at the MMA 8th a variety of exposure beams 3 , which depending on the position of each individual mirror 9 to the photosensitive layer 1 or be redirected to a room area next to it. The respective switching position of the individual mirrors 9 and that from the MMA 8th generated patterns depend on that on the photosensitive layer 1 structure to be generated. A control device 11 is used to control the MMA 8th depending on the given, on the photosensitive layer 1 structure to be generated.

The exposure beams 3 , which at the MMA 8th to the photosensitive layer 1 are deflected parallel to each other and their propagation direction is perpendicular to the photosensitive layer 1 , A lens 12 is used to reduce the size of the exposure rays (eg by a factor of 10) 3 or the level 10 with the MMA 8th on the photosensitive layer 1 ,

As in 1 can be seen, covers a respective exposure beam 3 only a part of the surface of a subarea assigned to it 2a - 2h , For full-surface structuring of the photosensitive layer 1 in an area to be structured has the exposure system 5 therefore a movement device 13 on which a linear motion unit 14 to move the MMA 8th along the X direction of an in 2 having shown XYZ coordinate system. A corresponding (not shown) linear motion unit is used for the displacement of the MMA in the Y direction. With the help of the movement device 13 can the MMA 8th in the X direction and in the Y direction over a distance which is approximately the edge length of a respective subarea 2a - 2h corresponds to the entire photosensitive layer 1 to structure in a desired area. The control device 11 is here with the linear motion unit 14 coupled to control their deflection in the X direction (as well as the other linear motion unit in the Y direction). It is understood that on the wafer 6 a plurality of adjacent areas are formed, which can be structured in the manner described above by the moving means 13 the movement of the MMA 8th (and possibly the wafer 6 ) controls suitably.

The exposure system 5 also has near field optics 15 which is in close proximity to the photosensitive layer 1 is arranged. Another linear motion unit 14a is with the control device 11 coupled to these in sync with the MMA 8th to move in the X direction. A corresponding coupling also exists with a further linear displacement unit (not shown) for shifting the near-field optical system 15 in the Y direction.

The near field optics 15 serves to convert a respective exposure beam 3 into an evanescent wave. In this way, the expansion of the exposure beams 3 to the size of a light spot 16 (see. 1 ), which is significantly smaller than the (diffraction-limited) extent 4 of the exposure beam 3 in front of the near field optics 15 , Through the near field optics 15 can thus the Resolution of the exposure system 5 be increased beyond the diffraction limit.

Several embodiments for the near field optics 15 will be described below on the basis of 3a -D described in more detail. The embodiments shown there are common, that is a distance a between the side of the near field optics 15 at which the evanescent wave emerges is on the order of the wavelength λ _{B of} the exposure radiation and in 3a -C is smaller than this wavelength λ _B.

This is favorable, since the intensity of each one from the near-field optics 15 escaping evanescent wave 17 exponentially with the distance "a" from the exit, ie: I (a) = I ₀ × Exp (-k · a), where I ₀ denotes the intensity at the exit and k a proportionality constant. Is the near field optics 15 therefore too far from the photosensitive layer 1 removed, the intensity of the evanescent wave is too low to the photosensitive layer 1 to expose.

At the in 3a example shown is the near field optics 15 formed as a shadow mask and has a for the exposure beams 3 transparent substrate 18 as a support and a photosensitive substrate 1 facing, plane barrier layer 19 made of chrome with a plurality of openings 20 whose diameter D is less than the used wavelength λ _{B of} the exposure beams 3 , The barrier layer 19 has a thickness of about 80 nm and is at the used wavelength λ _B of 193 nm for the exposure beams 3 no longer permeable. The through the lens 12 conditional, diffraction-limited extent (Airy slices) 4 the exposure beams 3 when entering the near field optics 15 is by means of the barrier layer 19 or the passage openings 20 on the in 1 illustrated extent of the light spot 16 reduced.

3b shows an embodiment of the near field optics 15 in which the transparent substrate 19 a surface structure in the form of conical tips 21 which serve as a micro-optic. The passages 20 in the barrier layer 19 are here at the extreme end of the conical tips 21 which is at a distance a from the photosensitive layer 1 is arranged, which is smaller than the wavelength λ _{B of} the exposure radiation.

At two in 3c In the examples shown, the light propagation direction of the exposure rays is 3 at an angle α to the near field optics 15 or to the photosensitive substrate 1 , This can be z. B. in the exposure system 5 from 2 be achieved by the parallel orientation of the MMA 8th to the photosensitive layer 1 is deviated. The exposure beams 3 are polarized parallel to the plane of incidence, which corresponds to the plane of the drawing. The polarization of the exposure beams 3 can be done by suitable polarizing filters (not shown). Because the laser light source 7 (see. 2 ) typically generates linearly polarized exposure radiation anyway, can, with appropriate alignment of the laser light source 7 relative to the photosensitive layer 1 if necessary, to dispense with a polarizing filter.

At the in 3c As shown, the near-field optic has a dielectric substrate 22 with a plurality of in the dielectric substrate 22 embedded metal tips 23 on, which are electrically isolated from each other. Here are the incident exposure beams 3 for excitation of surface plasmons in a respective metal tip 23 and induce there an alternating electric field, which at the tapered end of the metal tips 23 is maximally compressed and as an evanescent wave 17 emerges from these. At a small distance a between a respective tip 23 and the photosensitive layer 1 is the intensity of the evanescent wave 17 sufficient to the photosensitive layer 1 in a very small area around the metal tip 23 to illuminate around. If the mechanical resistance of the photosensitive layer 1 This allows the metallic tips 23 also be in direct contact with this.

In addition, to excite the surface plasmons, the wavenumber of the exposure beams used must be 3 be adapted to the plasma frequency of the metal used, which is via the dielectric substrate 22 can be done. In the present example, where the exposure beams 3 have a wavelength λ _B of about 193 nm, z. As aluminum as a material for the metallic tips 23 ,

At the in 3d shown embodiment, the near field optics 15 from 3c around a so-called super lens 24 extended. The super lens 24 is at the photosensitive layer 1 facing side of the near field optics 15 attached and consists of a first dielectric layer 24a and a second dielectric layer 24c , between which a metallic layer 24b is arranged. Also with the super lens 24 surface plasmons are excited. These allow a mapping of the near-field optics 15 escaping evanescent waves 17 on the photosensitive substrate 1 , where the evanescent waves 17 be transported almost undamped. This is possible because the super lens 24 one for the wavelength λ _{B of} the exposure 3 has negative refractive index. The thicknesses of the (plan) layers 24a -C are typically on the order of the wavelength λ _{B of} the exposure beams 3 , In the present example, a wavelength λ _B of about 193 nm, the use of a metallic layer 24b Made of aluminum proved favorable. As dielectric layers 24a , c can hereby z. B. quartz glass layers are used. As in 3d can also be seen, the distance a between the exit of the evanescent waves 17 and the photosensitive substrate 1 be chosen larger than the in 3a -C described examples. It is understood that a super lens 24 also at the in 3a -C shown near-field optics can be used.

As in 3c Shown is the exposure system 5 additionally a detector device 25 for spatially resolved detection of the intensity of the at the dielectric substrate 22 the near field optics 15 reflected exposure rays 3 exhibit. The intensity of the reflected light can be determined by such a spatially resolving detector device 25 , z. B. in the form of a CCD camera or the like, channel by channel, ie for each exposure beam 3 individually, be measured. In this way can indirectly the energy input of a respective exposure beam 3 or the evanescent wave generated by this 17 in the photosensitive layer 1 be measured, because the less energy in the photosensitive layer 1 is introduced, the more energy is reflected and vice versa.

Unlike the in 3a , b shown near-field optics 15 in the form of shadow masks, the energy transfer is more efficient in the excitation of surface plasons, because the plasmon absorbs the light energy "large area" and this essentially on the metallic tips 23 can give away again. At the in 3a , B described embodiments, the geometric relationship between the diameter D of the passage openings 20 and the total area of the shadow mask crucial.

Since the near field in the photosensitive layer 1 coupled intensity is highly distance dependent, can, as in 3c shown a distance determination device 26 for determining the distance between the near field optics 15 and the photosensitive substrate 1 in the exposure system 5 be arranged. The distance determination device 26 can the local distance a and in particular a possibly occurring tilting of the near field optics 15 with respect to the photosensitive substrate 1 on the basis of the detector device 25 determine recorded intensity. By determining the distance a at a plurality of locations, tilting of the near-field optics can take place 15 closed, which if necessary by means of manipulators (not shown), for. B. in the form of piezo actuators can be compensated. The with the aid of the distance determination device 26 certain distance a can be adjusted or regulated to a desired distance to allow a focus control or a focus position control.

If the distance a between the cone tips 21 and the photosensitive layer 1 varies locally varies, the exponential dependence of the tunneling efficiency of the distance a can be exploited to the resulting inhomogeneity of the light distribution on the photosensitive layer 1 by a suitable influencing of the intensity distribution in front of the near field optics 15 to compensate.

For this purpose, the detector device 25 and optionally also the distance determination device 26 with the control device 11 (see. 2 ), which evaluates the detected or measured data and in dependence on these one in front of the lens 12 arranged gray filter 27 which controls a channel-wise, ie individual modulation of the intensity of each individual exposure beam 3 allowed. The control device 11 modulates the intensity of the exposure beams 3 such that the most uniform possible intensity of the exposure beams 3 on the photosensitive layer 1 is obtained. It is understood that additionally or alternatively to the adjustment of the intensity, further measures for the modulation of the exposure beams 3 can be provided, for. B. an influence on the polarization of the exposure beams 3 with the help of channel-wise, ie individually modulating polarizer devices.

4 and 5 show two more examples of exposure equipment 5 in which the light-generating device 7 each of the in 2 shown differs. The light-generating device 7 from 4 has a lighting system 7b on which the from the laser beam source 7a outgoing laser radiation expands and a matrix arrangement in the form of an LCD array 8a illuminated homogeneously. The individual grid elements 9a (Pixels) of the LCD array 8a depending on the photosensitive layer 1 be turned on or off to be generated structure, so that a desired pattern of exposure beams 3 is obtained. The raster elements 9a can hereby z. B. have an extension of 2.9 microns × 2.9 microns at a size of 100 mm × 100 mm, as z. B. in the under " http://www.lgblog.de/2009/06/15/kleinstes-lcd-display-der-welt-mit-vga-auflosung/ "Described VGA resolution LCD array is the case.

The from the LCD array 8a generated light distribution of the exposure beams 3 gets from the lens 12 which is like in 2 has a numerical aperture NA = 1 on the image plane with the photosensitive layer 1 at least reduced by a factor of 10, so that on this one Image of the pattern of the active grid elements 9a of the LCD array 8a z. B. with a size of 10 mm × 10 mm is formed. The extent of each exposure beam 3 on the photosensitive layer 1 This corresponds to the resolution (after Abbe) of the lens used 12 ,

When looking for the lens 12 a numerical aperture NA = 1, a k-factor of 0.5 (for example, generated by an annulus aperture in the pupil plane of the objective 12 ), and a wavelength λ _{B of} the exposure beams 3 of 193 nm, the formula for the still possible resolvable distance between two light points (d = k × λ _B / NA) gives d = 0.5 × 193 nm / 1, ie approximately 100 nm. If this is done by appropriate measures (see above or below) actually achieved resolution to 10 nm, so on the photosensitive layer 1 from an incident exposure beam 3 The recorded area of 100 nm × 100 nm should be scanned in at least 20 × 20 = 400 sub-steps.

For this purpose, the LCD array 8a with the help of the movement device 13 or a linear motion unit 14 in steps of 5 nm or continuously (at constant speed) in the Z-direction, the movement being synchronized with the exposure, ie the switchable raster elements 9a are switched on or off depending on the structure to be generated. It is understood that a second (not shown) linear displacement unit of the displacement of the LCD array 8a in the Y direction. It is further understood that additionally or alternatively, the wafer 6 by means of suitable displacement devices in the plane in which the photosensitive layer 1 is arranged, can be moved.

Assuming that the LCD array 8a operating at a switching frequency of 500 Hz, the 10 mm × 10 mm field on the wafer can 6 be exposed in about 0.8 seconds. A commercial wafer 6 has about 700 such 10 mm × 10 mm cells and could therefore be exposed after about 560 seconds, resulting in a throughput of about 8 wafers per hour. The limiting factor for the exposure speed is mainly the switching frequency of the raster elements 9a (Pixels) of the LCD array 8a (Switching time approx. 2 ns). It is understood that with LCD arrays, which are developed in the future, possibly an increase in the switching frequencies takes place or by adapting LCD arrays to the present application (only on / off), the switching times can be increased, so that the with the in 4 shown exposure system 5 achievable throughput can be increased.

A significant reduction in the switching times is in the case of 5 shown exposure system 5 possible, in which the light-generating unit 7 a raster arrangement in the form of a laser diode array 8b with a plurality of switchable laser diodes 9b as light sources, the number of which substantially coincides with that of in 4 shown LCD arrays 8a matches. In such a laser diode array 8b The switching times can be smaller by about a factor of 2000, so that a theoretical throughput of about 16000 wafers is possible, ie the switching times do not have a limiting effect, provided that sufficient exposure radiation is present. In place of the laser diodes 9b It is also possible to use OLEDs, but they only produce a power of about 10 mW / cm ² on the photosensitive substrate 1 while the power that can be generated with a conventional 193 nm laser is about 100 W / cm ² , ie about 10,000 times greater. Due to the low available light intensity, only about 5 wafers per hour may possibly be exposed with an OLED array. Also, OLEDs work with visible light, allowing the extension of each onto the photosensitive layer 1 incident exposure beams 3 is relatively large.

In the 4 and 5 shown exposure systems 5 can with the in 2 or in 3a -D shown near field optics 15 combined to achieve the desired increase in resolution. Instead of the use of near-field optics described above 15 it is also possible to increase the resolution of the photosensitive layer 1 to use to increase the resolution.

To explain this procedure shows 6 on the photosensitive layer 1 depending on the position P (in the X direction) incident intensity I of three adjacent exposure beams 3 , which each have a central intensity maximum I _MAX . The photosensitive layer 1 has an intensity threshold I _S , which in the present case is approximately 10% of the maximum intensity I _MAX . The intensity threshold I _S defines the intensity at which the photosensitive layer 1 from a second state B to a first state A. The second state B is assumed here if the intensity I is below the threshold value I _S , the first state A is assumed, provided that the intensity I is above the threshold value I _S. The maximum intensity I _{MAX of} the exposure beams 3 was chosen to be above the intensity threshold I _S.

Regarding the two states A, B of the photosensitive layer 1 For example, the transition from the second state B to the first state A can be irreversible. In this case, the photosensitive layer 1 after exceeding the intensity threshold I _S no longer return to the second state B and remains in the permanently chemically altered state A or is transferred during subsequent fixation in a further, permanently chemically altered state (so-called Alzheimer's Resist). Optionally, in such a resist, it is necessary to perform a thermal treatment between two consecutive exposures, which causes a kind of "debeltering" of the previously poorly exposed areas. In particular, as the photosensitive layers in this case, highly non-linear exposure-responsive resists can be used.

When using a photosensitive layer (resist) having such an irreversible transition, the intensity of the exposure rays typically becomes 3 different from the one in 6 illustrated case selected so that the intensity threshold I _{S is} relatively close to the intensity maximum I _MAX , z. For example, I _S = 0.9 × I _MAX can be selected. In this way, the photosensitive layer becomes only in a relatively small surface area 16 (see. 1 ) from Z. Less than 20% or less than 10% of the surface area 4 a respective incident exposure beam 3 from the second state B to the first state A, whereby the desired increase in the resolution can be realized.

Alternatively to the use of a photosensitive layer 1 , which by means of the exposure beams 3 It is also possible to switch a photosensitive layer irreversibly from a second state B to a first state A. 1 in which the transition from the second state B to the first state A (and vice versa) is reversible. The photosensitive layer 1 In this case, it can be designed so that it can be converted into a permanently changed chemical state only in the second state B, but not in the first state A.

A photosensitive layer 1 with such properties can be realized by certain switchable molecules, in particular in the form of switchable organic dyes. The switching of the molecules between the two states A, B can in this case be caused by light, wherein the wavelength of the light which is used for switching from the second state B to the first state A, differs from the wavelength of the light which is used for switching from first state A in the second state B is used. In fluorescent organic dyes, the transition from the second, excited state B in the first state A z. B. done by stimulated emission.

First, the entire photosensitive layer is transferred from the first state A to the second state B, and subsequently the photosensitive layer 1 on the in 6 shown inhomogeneously illuminated, it remains only in a relatively narrow intensity range in the second state B and can be converted by this in a permanently chemically altered state C. In this way, the resolution during exposure can also be increased.

An exposure system 5 which is designed for this purpose is in 9 shown. The exposure system 5 corresponds to that of 4 and is an additional light-generating device 30 complements which an excitation light source 31 for generating excitation radiation 32 and a fixation light source 34 for generating fixation radiation 33 to transfer the photosensitive layer 1 from the second state B to the permanently altered chemical state C.

During exposure with the exposure system 5 First, the photosensitive layer 1 large area and homogeneous with the excitation radiation 32 irradiated, including a partially transparent mirror 36 is used, which the excitation radiation 32 on the photosensitive layer 1 deflects. The excitation radiation 32 in this case has an excitation wavelength λ _A , in the present example, in which the photosensitive layer 1 is formed from an organic dye (eg RH414), can be in the range between 400 nm and 650 nm and z. B. at a wavelength of λ _A = about 500 nm. The photosensitive layer 1 is due to the excitation radiation 32 transferred from the first state A in the second state B. In a subsequent step, the light-generating unit 7 used the exposure beams 3 on the photosensitive layer 1 to be irradiated whose wavelength in the present case at λ _B = 745 nm.

The exposure beams 3 generate at the photosensitive layer 1 an intensity profile, the z. B. as in 7 can be shown shown. The individual exposure beams 3 overlap and overlap to a substantially homogeneous intensity I _HOM , which only in a small area 37 is interrupted and drops almost to zero. The recessed area 37 associated exposure beam 3 or an associated grid element 9a is turned off. The intensity I _HOM outside the recessed area 37 is greater than the intensity threshold I _S and thus sufficient to the photosensitive layer 1 from the second state B to the first state A.

Only in the recessed area 37 the intensity I remains along a distance d _min below the intensity switching threshold I _S , so that the photosensitive layer 1 remains in the second state B along this route. Will in a subsequent step using the fixation light source 34 fixing radiation 33 large area on the photosensitive layer 1 Applied, this is only in the recessed area 37 converted into the permanently altered chemical state C. As in 7 can also be seen, the distance d _{min is} smaller than the distance d, which is the extension of an exposure beam 3 corresponds so that by the measures described above, the resolution of the exposure system 5 can also be increased beyond the diffraction limit or the maximum resolvable distance d addition.

When using a wavelength λ _B of about 500 nm, a k-factor of 0.5 and a numerical aperture NA = 1, the maximum resolvable distance d = 0.5 × 500 nm / 1 = 250 nm. Substituting the contrast Resolution d _min than 10 nm, the corresponding subregion of about 250 nm × 250 nm must be scanned at least in 25 × 25 = 625 steps, in which case, instead of a plurality of discrete steps, if necessary, a continuous movement with constant Speed can be made. The three consecutive steps of stimulating, exposing and fixing must be done by the control device 11 be coordinated with the respective shift.

At the in 9 shown embodiment of the exposure system 5 is like in 4 the throughput through the switching speed of the LCD array 8a limited by about 500 Hz, so that a throughput of about four wafers per hour is possible. Alternatively, an exposure system 5 analogous to 5 used as they are in 10 is shown. The exposure system 5 from 10 is different from that of 5 initially by the fact that instead of a laser diode array an OLED array 8c with a plurality of OLEDs 9c is used. The excitation light source 31 as well as the fixing light source 34 are here as in 9 trained and the excitation, exposure and fixation that must be made in each step of the scanning is also by means of the control device 11 coordinated or synchronized.

When using the OLED array 8c can be related as above 5 described the switching speed increased by about a factor of 2000. Accordingly, a throughput of about 8000 wafers per hour would be possible. The excitation light source 31 and the fixing light source 34 should work in the MHz range, but this is easily possible when using laser light sources with wavelengths λ _A , λ _F in the visible range. The OLED array 8c can in this case by means of the movement device 13 with a constant synchronized speed of z. B. be moved about 0.1 m / sec.

The procedure described above, in which the minimum of the respective exposure beams is used as a "write signal", enables a particularly high resolution, since no image-relevant secondary radiation by fluorescence photons takes place here.

As an alternative to the procedure described above, it is also possible with the help of the in 9 and 10 shown exposure systems 5 to perform an exposure at which the excitation radiation 32 not homogeneous on the photosensitive layer 1 meets, z. B. by the excitation light source 31 is provided with a suitable illumination system and, if appropriate, a further grid arrangement (not shown) or a (gray) filter. Hits the excitation radiation 32 with a location-dependent intensity I _A simultaneously with the exposure beams 3 with a location-dependent intensity I _B on the photosensitive layer 1 , as is known from STED microscopy, an intensity distribution I _AB = I _A × Exp (-I _B ) results in the superimposition of the two intensity distributions (cf. 8th ), which in contrast to in 7 shown intensity distribution instead of a limited to a very small space area minimum has a limited to a very small space area maximum (peak with extension in the nm range).

To the intensity profile I _AB of 8th with the pronounced peak, shows is the intensity of the excitation radiation 32 chosen so that this between two adjacent exposure beams 3 has a maximum I _MAX , at which the total intensity I _AB becomes maximum. As with the related 6 and 7 Exposure processes described causes the excitation radiation 32 a transition from a first state A to a second state B, whereas the exposure beams 3 cause the reverse effect, ie a transition from the second state B in the first state A by stimulated emission. Only in the region of the peak remains the photosensitive layer 1 in the second state B and can by means of Fixierlichtquelle 34 be converted into a permanently altered chemical state C. It is understood that the use of fixation light can be dispensed with if the transition between the first state A and the second state B is irreversible.

That related to 8th The procedure described here represents the transfer of the principle of STED microscopy to lithography. When using organic Dyes as photosensitive layer 1 These remain excited only in the region of the peak and can, for. B. via the Förster resonance energy transfer (dipole-dipole interaction) or via the Dexter energy transfer (exchange of electrons) the neighboring molecules of the photosensitive layer 1 chemically transform and fix it. A "secondary radiation" by fluorescence photons, which would lead to expansion, also does not take place in this case.

STED microscopy typically becomes a photosensitive layer 1 used, which consists of a switchable organic dye, wherein the second fluorescent state B can be returned by stimulated emission in the first state A of the switchable organic dye. Dyes which can be used for this purpose are available in large numbers, cf. z. B. " http://www.mpibpc.mpg.de/groups/hell/STED_Dyes.html ". If necessary, it is also possible to prepare new organic dyes which are optimized with regard to the respective required chemical properties.

It will be understood that the exposure described above is not limited to the use of fluorescent dyes in which the feedback from the second state B to the first state A is based on stimulated emission. It can rather be in the two states z. Also, for example, they may be different structural isomerism states (eg, cis-trans isomers) of a switchable organic dye, a first state of which is a fluorescent state, while the second state is not. This principle is used, for example, in the so-called RESOLFT (Reversible Saturable Optical Fluorescence Transitions) microscopy, where in addition to organic dyes z. B. also switchable proteins can be used. The use of such materials for the photosensitive layer has the advantage that the intensity required to overcome the intensity threshold is less than is typically the case for stimulated emission transitions.

Other types of photosensitive layers may also be used for the exposure processes described herein. It is essential here only that the photosensitive layer has molecules with at least two states, between which reversible can be switched.

In summary, in the manner described above, a parallel exposure of a wafer can take place in a plurality of partial regions whose extent is in each case of the order of magnitude of the diffraction limit. As a result of the measures described above, the resolution can be increased beyond the diffraction limit so that structuring within the respective subareas is possible by scanning exposure. In this way, an effective and inexpensive exposure of photosensitive layers with high resolution can be achieved.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 7425713 B2 [0004]
• US 2006/0044985 A1 [0027, 0036]

Cited non-patent literature

• "Near-Field Lithography as Prototype Nano-Fabrication Tool", Microelectronic Engineering 84 (2007) 705-710 by Yasuhisa Inao et al. [0003]
• http://en.wikipedia.org/wiki/Surface_Plasmon [0021]
• "Super-resolution near-field lithography using planar silver lenses" by David OS Melville et al. (Invited Poster, MNE-2005 ID 00709, "http://www.mne05.org/3-c_01.pdf") [0023]
• http://www.lgblog.de/2009/06/15/kleinstes-lcd-display-der-welt-mit-vga-auflosung/ [0082]
• http://www.mpibpc.mpg.de/groups/hell/STED_Dyes.html [0106]

Claims (30)

Exposure system ( 5 ) for structured exposure of a photosensitive layer ( 1 ), comprising: a generating device ( 7 ) for generating a plurality of exposure beams ( 3 ), each exposure beam ( 3 ) a subarea ( 2a - 2h ) of the photosensitive layer ( 1 ), a movement device ( 13 ) for moving the exposure beams ( 3 ) relative to the respectively assigned subregion ( 2a - 2h ), and one in front of the photosensitive layer ( 1 ) arranged near field optics ( 15 ) for generating a light spot ( 16 ) on the photosensitive layer ( 1 ) whose extent is smaller than the extent ( 4 ) of a respective exposure beam ( 3 ) in front of the near field optics ( 15 ). Exposure plant according to Claim 1, in which one of the photosensitive layers ( 1 ) facing side of the near field optics ( 15 ) at a distance (a) from the photosensitive layer ( 1 ) which is smaller than the wavelength (λ _B ) of the exposure beams (FIG. 3 ). Exposure system according to one of the preceding claims, further comprising: a detector device ( 25 ) for detecting the intensity of the near field optics ( 15 ) reflected exposure beams ( 3 ). An exposure apparatus according to claim 3, further comprising: distance determining means (10); 26 ) for determining the distance (a) between the near field optics ( 15 ) and the photosensitive layer ( 1 ) based on the detected intensity. Exposure system according to one of the preceding claims, further comprising: one in front of the near field optics ( 15 ) arranged filter device ( 27 ) for influencing the intensity and / or the polarization of a respective exposure beam ( 3 ). Exposure system according to claim 5, further comprising: a control device ( 11 ) for controlling the filter device ( 27 ) in dependence on the by means of the detector device ( 25 ) detected intensity. Exposure system according to one of the preceding claims, in which the near-field optical system ( 15 ) a shadow mask ( 18 . 19 ) with a plurality of passage openings ( 20 ) whose diameter (D) is preferably smaller than the wavelength (λ _B ) of the exposure beams ( 3 ). Exposure plant according to Claim 7, in which the shadow mask is exposed for the exposure beams ( 3 ) transparent substrate ( 18 ) and one of the photosensitive layers ( 1 ) facing barrier layer ( 19 ), at which the plurality of passage openings ( 20 ) is formed. Exposure plant according to Claim 8, in which the transparent substrate ( 18 ) at its photosensitive layer ( 1 ) facing side is structured. Exposure plant according to one of Claims 1 to 6, in which the light propagation direction of the exposure beams ( 3 ) at an angle (α) to the near-field optic ( 15 ) and in which the near field optics ( 15 ) a dielectric substrate ( 22 ) with a plurality of in the dielectric substrate ( 22 ) embedded, tapered metallic structures ( 23 ) having. Exposure system according to one of the preceding claims, further comprising: a super-lens ( 24 ) for mapping from near-field optics ( 15 ) evanescent waves ( 17 ) on the photosensitive layer ( 1 ). Exposure system ( 5 ) comprising: a substrate ( 6 ) with a photosensitive layer ( 1 ), a generation facility ( 7 ) for generating a plurality of exposure beams ( 3 ) with an exposure wavelength (λ _B ), each exposure beam ( 3 ) a subarea ( 2a - 2h ) of the photosensitive layer ( 1 ) and the generating device ( 7 ), exposure beams ( 3 ) with a maximum intensity (I _MAX ) which exceeds an intensity threshold value (I _S ) for transferring the photosensitive layer ( 1 ) from a second state (B) to a first state (A), a movement device ( 13 ) for moving the exposure beams ( 3 ) relative to the respectively assigned subregion ( 2a - 2f ), as well as an excitation light source ( 31 ) for generating excitation radiation ( 32 ) with an excitation wavelength (λ _A ) for transferring the photosensitive layer ( 1 ) from the first state (A) to the second state (B). Exposure system according to claim 12, in which the transition from the first state (A) to the second state (B) is reversible and the photosensitive layer ( 1 ) can only be converted into a permanently changed chemical state (C) in the second state (B). An exposure apparatus according to claim 13, further comprising: a fixation light source ( 34 ) for transferring the photosensitive layer ( 1 ) from the second state (B) to the permanently altered chemical state (C). Exposure plant according to one of Claims 12 to 14, in which the subareas ( 2a - 2h ) to which the respective exposure beams ( 3 ), at least partially overlap. Exposure system according to one of Claims 12 to 15, in which the excitation light source ( 30 ), excitation radiation ( 32 ) with a location-dependent varying intensity profile (I _A ) on the light-sensitive layer ( 1 ), the excitation radiation ( 32 ) preferably between two adjacent exposure to the photosensitive substrate exposure beams ( 3 ) has a maximum intensity (I _MAX ). An exposure apparatus according to any one of claims 12 to 16, wherein the transition from the second state (B) to the first state (A) is irreversible. Exposure plant according to one of Claims 12 to 17, in which the photosensitive layer ( 1 ) has a switchable organic dye or a switchable chalcogenide. An exposure apparatus according to claim 18, wherein the second state (B) of the switchable organic dye is stimulated by emission to the first state (A) of the switchable organic dye. An exposure apparatus according to claim 18 or 19, wherein the first and second states (A, B) are different structural isomerism states of the switchable organic dye. Exposure plant according to one of the preceding claims, in which the generating device ( 7 ) a grid arrangement ( 8th . 8a - 8c ) with a plurality of switchable raster elements ( 9 . 9a - 9c ) for switching on or off a respective exposure beam ( 3 ) depending on one on the photosensitive layer ( 1 ) is formed to be generated structure. Exposure plant according to Claim 21, in which the raster elements ( 8a - 8c ) of the grid arrangement ( 9a - 9c ) as switchable diaphragms for a respective exposure beam ( 3 ) are formed. Exposure system according to one of Claims 21 or 22, in which the raster arrangement is in the form of a LCD array ( 9a ), as a laser diode array ( 9b ) or as an OLED array ( 9c ) is trained. Exposure system according to Claim 21, in which the raster elements are in the form of switchable reflectors ( 9 ) for a respective exposure beam ( 3 ) are formed. Exposure system according to Claim 24, in which the raster arrangement is in the form of a micro-mirror array ( 8th ) is trained. Exposure plant according to one of Claims 21 to 25, in which the movement device ( 13 ) at least one displacement unit ( 14 ) for shifting the grid arrangement ( 8th . 8a - 8c ) relative to the photosensitive layer ( 1 ), preferably in synchronism with the near field optics ( 15 ), having. Exposure plant according to one of Claims 21 to 26, in which the generating device ( 7 ) a lighting device ( 7b ) for illuminating the grid arrangement ( 8a ) having. An exposure apparatus according to any of claims 21 to 27, further comprising: an objective ( 12 ) for reducing the size of the grid arrangement ( 8th . 8a C) on the photosensitive layer ( 1 ) or on the near field optics ( 15 ). Process for the structured exposure of a photosensitive layer ( 1 ), comprising: generating a plurality of in particular parallel exposure beams ( 3 ), each exposure beam ( 3 ) a subarea ( 2a - 2h ) of the photosensitive layer ( 1 ), moving the exposure beams ( 3 ) relative to the respectively assigned subregion ( 2a - 2h ), and arranging a near-field optical system ( 15 ) in front of the photosensitive layer ( 1 ) for converting a respective exposure beam ( 3 ) into an evanescent wave ( 17 ) for generating a light spot ( 16 ) on the photosensitive layer ( 1 ) whose extent is smaller than the extent of a respective exposure beam ( 3 ) in front of the near field optics ( 15 ). Process for the structured exposure of a photosensitive layer ( 1 ) comprising: generating a plurality of exposure beams ( 3 ), each exposure beam ( 3 ) a subarea ( 2a - 2h ) of the photosensitive layer ( 1 ) and moving the exposure beams ( 3 ) relative to the respectively assigned subregion ( 2a - 2h ), the exposure beams ( 3 ) with a maximum intensity (I _MAX ) which is greater than an intensity threshold value (I _S ) for transferring the photosensitive layer ( 1 ) from a second state (B) to a first state (A), exciting the photosensitive layer with excitation radiation ( 32 ) for transferring the photosensitive layer ( 1 ) from the first state (A) to the second state (B), and recycling the photosensitive layer (FIG. 1 ) from the second state (B) to the first state (A) in a non-patterned area.

Images