Lithography apparatus comprising a plurality of individually controllable write heads

The invention relates to a lithography apparatus comprising a plurality of write heads for writing to substrates.

Furthermore, the invention relates to a write head for such a lithography apparatus.

The present patent application claims the priority of the German patent application 10 2014 224 314.9, the disclosure content of which is hereby comprised by reference.

Photolithographic patterning methods are typically used for producing microstructures , in which methods the desired structure is transferred into a photosensitive layer arranged on a substrate and the substrate is patterned in a desired manner by means of the exposed photosensitive layer in subsequent chemical and physical processes. Either imaging or directly writing exposure systems are used for transferring the respective structures into the photosensitive layer. In the first case, a pattern produced in a mask beforehand is projected onto the substrate in a greatly reduced fashion by means of a complex projection system. By using suitable masks, with the aid of a projection system it is possible to transfer a relatively large number of structures to the substrate all at once, which becomes apparent in a high throughput, in particular. On account of the high precision required during the imaging of structures in the micrometres and nanometres range, projection exposure systems are

constructed in a very complex fashion and are therefore also very cost-intensive both in terms of procurement and in operation. By contrast, directly writing lithography exposure systems, in which the desired structures are written directly into the photosensitive layer on the substrate wafer by means of a laser, manage with a significantly less complex

construction. However, the writing speed of such directly writing laser systems does not suffice to obtain a throughput comparable with the projection exposure systems.

Therefore, it is an object of the invention to provide a directly writing lithography exposure apparatus which firstly can be constructed expediently from standard components and at the same time enables a sufficiently high throughput. This object is achieved by means of a lithography exposure

apparatus according to Claim 1. Furthermore, the object is achieved by means of a write head for a lithography apparatus according to Claim 10, and by means of a method according to Claim 17. Further advantageous embodiments are specified in the dependent claims.

The invention provides a lithography apparatus for writing to substrate wafers comprising a light generating device

comprising one or a plurality of light sources for generating light, a light transferring device comprising a number of optical waveguides for transferring the light from the light generating device to a writing device, the writing device comprising a plurality of individually controllable write heads for projecting the light from the one or the plurality of light sources in different regions of a substrate wafer, a transport device for moving the substrate wafer relative to the writing device in a predefined transport direction, and a control device for controlling the writing process on the substrate wafer. By using a plurality of individually

controllable write heads, it is possible to significantly increase the exposure time of the substrate wafer and, in association therewith, also the throughput of the lithography apparatus .

In one embodiment it is provided that the write heads in each case comprise a light input coupling device for coupling the light from a plurality of optical waveguides into the respective write head, an optical device for generating a light spot composed of the light beams from the individual optical waveguides on the substrate wafer, and a scanning device for moving the light spot in a scanning manner on the substrate wafer in a scanning direction transversely with respect to the transport direction. By integrating the components into a single housing, it is possible to produce particularly compact write heads. By using light beams from a plurality of optical waveguides, it is possible to generate a particularly light-intensive light spot on the substrate. The latter in turn enables particularly high scanning speeds, which becomes apparent in a higher throughput. Furthermore, by setting the light intensity of the individual light beams, it is possible to vary the profile of the light spot used for writing. Different distortions of the writing beam can thus be compensated for. Furthermore, the resolution obtained during the writing process can thus also be varied.

In a further embodiment it is provided that the scanning device of at least one write head comprises an oscillating scanning mirror, which generates a sinusoidal movement trajectory of the light spot on the substrate wafer moving in the transport direction. In this case, the control device is designed to vary the light intensity of at least one of the light beams forming the light spot on the substrate wafer in a manner dependent on the current speed of the light spot on the substrate wafer during a scanning period. By varying the light intensity, it is possible to compensate for a different exposure of the substrate strip to be written to in regions of the turning points of the sinusoidal movement trajectory and, consequently, to achieve a homogeneous exposure over the entire width of the strip-shaped region to be written to. In particular, the light intensity is reduced in a suitable manner in the regions of the turning points of the sinusoidal trajectory. This can be carried out jointly both for

individual light beams and for all light beams. With the use of pulsed light beams, a reduction of the light intensity can also be achieved by adapting the duty ratio of switch-on and switch-off times. In this case, in the regions of the turning points, the switch-on times of the light beams or of the respective light sources are reduced and/or the corresponding switch-off times are lengthened.

In a further embodiment, the write heads are designed to scan in each case separate window-shaped regions of the substrate wafer, wherein the window-shaped regions of the individual write heads are arranged in a manner offset relative to one another in the transport direction in such a way that the strip-shaped regions of the substrate wafer which are exposed by the individual write heads on account of the transport movement of the substrate wafer relative to the writing device form a continuous area. By this means, even relatively large areas can be written to particularly rapidly and precisely .

A further embodiment provides for the write heads of the writing device to be arranged one behind another and/or alongside one another in the transport direction of the substrate wafer. The arrangement one behind another allows the use of write heads whose diameter turns out to be

significantly wider in comparison with their scanning region. By arranging the scanning heads alongside one another, it is possible for a plurality of groups comprising in each case a number of scanning heads arranged one behind another to be combined to form larger writing units.

In a further embodiment it is provided that provision is made of a detection device comprising a plurality of measuring devices assigned in each case individually to the individual write heads and serving for monitoring the width and/or the orientation of the strip-shaped regions exposed via the individual write heads. In this case, each measuring device comprises at least two photodiodes arranged one behind another in the scanning direction of the light beam in a scanning region of the respective write head. With the aid of said detection device, the strip-shaped regions exposed by the different write heads can be coordinated with one

another, with the result that a seamless overall area results therefrom. In this case, the light beams can be measured particularly simply with the aid of the photodiodes arranged below the write head.

In an alternative embodiment it is provided that a measuring device assigned to a write head comprises two reflective structures, which are arranged in each case on a substrate wafer in a manner distributed along a scanning direction transversely with respect to the transport direction and in a manner enabling capture by the light spot of the respective write head, and a light detector, which is arranged in the respective write head and detects the light reflected from the reflective structures. A simple and precise measurement of the light beams can be obtained with the aid of this measuring device, too.

In a further embodiment it is provided that the measuring device is designed to individually detect each light beam of the light spot composed of the light beams from the

individual optical waveguides. The profile of the light spot writing on the substrate wafer can be monitored by this means. This in turn makes it possible to produce structures having a higher resolution in the x-direction.

In a further embodiment it is provided that each light source is in each case assigned to a single write head, wherein the respective light source is individually drivable. By this means, the light intensity of the light beams of the

respective write head can be achieved particularly simply by modulation of the light source. A specific electro-optical modulation device can therefore be omitted. In a further embodiment it is provided that a light source is assigned to a plurality of write heads, wherein each of said write heads is assigned an individual electro-optical

modulator for modulating the light intensity of the light provided by the light source. This makes it possible to use individual high-power light sources.

In a further embodiment it is provided that each of the optical waveguides assigned to a write head is respectively assigned a separately drivable electro-optical modulator. The light intensity of the individual beams of the write head can thus be controlled individually. By this means, in turn, the profile of the light spot generated by the respective write head on the substrate surface can be varied particularly simply .

The invention furthermore provides a write head for a

lithography apparatus, wherein the write head comprises a light input coupling device for coupling the light from a plurality of optical waveguides into the write head, an optical device for generating a light spot composed of the light beams from the individual optical waveguides on the substrate wafer, and a scanning device for moving the light spot in a scanning manner on the substrate wafer in a

scanning direction transversely with respect to the transport direction. Such a write head can be constructed particularly compactly. By virtue of its small size, it is possible for a multiplicity of such individually drivable write heads to be combined to form larger writing units. Furthermore, the integration of the respective components into the write head housing permits particularly rapid installation and

demounting of the respective write head.

In a further embodiment it is provided that the light input coupling device comprises a plurality of waveguide structures formed in a transparent substrate, said waveguide structures, on the input side, being arranged at least at a distance from one another that corresponds to the diameter of the

individual optical waveguides and, on the output side, converging to form a spatially narrowly delimited waveguide bundle. With the aid of such waveguide structures, the light beams from the individual optical waveguides that are

required for the composite light spot can be aligned very precisely with respect to one another.

In a further embodiment it is provided that the input

coupling device comprises an arrangement of a plurality of microlenses and a telescope optical unit disposed optically downstream of the microlenses, wherein each of the

microlenses is designed to image in a magnified fashion the output of an optical waveguide assigned to the respective microlens. The telescope optical unit is furthermore designed to reduce the imaging generated in this case, such that the light spot composed of the light beams of the individual optical waveguides arises on the substrate wafer. A precise alignment of the light beams of the individual optical waveguides can be realized relatively simply with the aid of the microlenses, too.

In a further embodiment it is provided that the scanning device comprises at least one scanning mirror which is movable about a scanning axis and which is designed to guide the light spot imaged on the substrate wafer in a periodic scanning movement over the substrate wafer, said periodic scanning movement being carried out transversely with respect to the transport direction of the substrate wafer. With the aid of such a scanning device, it is possible to expose a relatively wide strip-shaped region by means of the light spot of a write head.

In a further embodiment it is provided that the scanning device is furthermore designed to perform a periodic line compensation movement of the light spot on the substrate wafer. With the aid of the periodic line compensation movement, it is possible to realize rectangular movement trajectories of the light spot on the substrate wafer, which enables a particularly effective exposure of the substrate area. Overall, it is thus possible to increase the writing speed of the write head and thus also the throughput of the lithography apparatus.

Finally, in a further embodiment it is provided that the optical device comprises a collimator disposed optically upstream of the scanning device and serving for generating parallel light beams and a telecentric imaging optical unit and/or f-theta lens disposed optically downstream of the scanning device and serving for focussing the parallel light beams on the substrate wafer. With the aid of these devices, it is possible to obtain a particularly high precision during the projection of the light spot on the substrate wafer.

The invention furthermore provides a method for writing to a substrate wafer with the aid of a lithography apparatus, wherein the substrate wafer is moved in a transport direction and wherein a plurality of light beams are projected onto the substrate wafer in order to generate on the substrate wafer a light spot formed from a plurality of individual light spots. The light spot is furthermore moved in an oscillating fashion transversely with respect to the transport direction in order to generate a sinusoidal movement trajectory of the light spot on the substrate wafer. In this case, the light

intensity of at least one of the light beams is varied during a scanning period in a manner dependent on the current speed of the light spot on the substrate wafer. By varying the light intensity, it is possible to compensate for the

different exposure of the substrate strip to be written to and, consequently, to achieve a homogeneous exposure over the entire width of the strip-shaped region to be written to. In particular, the light intensity is reduced in the regions of the turning points of the sinusoidal trajectory. This can be carried out jointly both for individual light beams and for all light beams. With the use of pulsed light beams, a reduction of the light intensity can also be achieved by adapting the duty ratio of switch-on and switch-off times. In this case, in the regions of the turning points, the

switch-on times of the light beams or of the respective light sources are reduced and/or the corresponding switch-off times are lengthened.

The invention is described in greater detail below with reference to figures, in which:

Figure 1 schematically shows a lithography apparatus

according to the invention with a writing device comprising a plurality of write heads;

Figure 2 shows by way of example a write head for a

lithography apparatus with a multiplicity of write heads arranged in matrix form;

Figure 3 shows by way of example the construction of a write head of the writing device from Figure 2;

Figure 4 shows by way of example an input coupling device for coupling a plurality of optical waveguides into a write head from Figure 3;

Figure 5 shows an alternative embodiment of the write head with an input coupling device comprising a microlens

arrangement ;

Figure 6 shows by way of example the distribution of the light intensity of a light spot formed from a plurality of light beams;

Figure 7 shows the distribution of the light intensity in the case of a light spot whose width is reduced by modulation of the outer light beams; Figure 8 schematically shows the exposure process of a substrate strip by means of an oscillating light spot;

Figure 9 schematically shows an alternative form of scanning the substrate by means of a light spot guided in a

rectangular trajectory over the substrate;

Figure 10 schematically shows the scanning process of a continuous substrate area by means of a matrix-type

arrangement of a plurality of write heads;

Figure 11 schematically shows an alternative arrangement of the write heads for realizing a closed scanning area;

Figure 12 schematically shows the construction of a detection device realized by means of photodiodes and serving for monitoring the writing beam of a write head of the

lithography apparatus;

Figure 13 schematically shows a plan view of a detection device from Figure 12 arranged below the substrate wafers;

Figure 14 shows the basic construction of an alternative detection device, which has a test substrate having

reflective structures and serving for monitoring the writing process of a write head of the lithography apparatus;

Figure 15 shows a plan view of a test substrate arranged between two regular substrate wafers;

Figure 16 shows a diagram with temporal profiles of different variables for illustrating the manner of operation of the detection device;

Figure 17 shows a scanning movement of the light spot with a relatively large amplitude and long dark phases; Figure 18 shows a scanning movement of the light spot with a relatively small scanning amplitude and for avoiding dark phases ;

Figure 19 shows a first partial exposure pattern during the falling edges of the scanning movement; and

Figure 20 shows a second partial exposure pattern during the rising edges of the scanning movement.

In order to realize a novel lithography apparatus, the intention is to use a preferably fixed compact write device comprising a plurality of individually drivable scanning write heads. In this case, the write heads are arranged above the substrate in such a way that a seamless exposure or inscription of the entire substrate surface is carried out by means of a transport movement of the substrate below the writing device. Figure 1 schematically shows the basic construction of the lithography apparatus 100 according to the invention. In this case, such a lithography apparatus 100 comprises a light generating device 110 for generating light having a desired wavelength and coherence, a light

transferring device 120 for transferring the light from the light generating device 110 to the writing device 140, the writing device 140 comprising a plurality of individually operating write heads 200i, 200 ₂ , 2ΟΟ3 for writing to a substrate wafer 3ΟΟ ₂ (wafer) by means of a plurality of light beams 401i, 401 ₂ , 4OI3, a transport device 150 arranged below the writing device 140 and serving for precisely moving a substrate wafer 3ΟΟ ₂ during the writing process below the writing device 140, and a control device 170 for coordinating the operation of the individual components during the writing process. For the purpose of monitoring and calibration of the writing device 140, the lithography apparatus 100 can

furthermore comprise a specific detection device 160. The writing device 140 forms a central part of the lithography apparatus 100 according to the invention, said writing device substantially consisting of a specific

arrangement of a plurality of write heads. The writing device 140 comprises means for precisely positioning and aligning the write heads 200i within the writing device 140. The write heads 200i here are in each case designed to write to the semiconductor wafer 300 ₂ by means of an individually

controllable light beam 401±. For this purpose, each write head 200ι, 2ΟΟ2, 2ΟΟ ₃ is connected to one or a plurality of light sources 111±, 112i, 113± of the light generating device 110 by means of a plurality of optical waveguides 122 _j of an optical waveguide group 121i individually assigned to the respective write head 200i. In the present exemplary

embodiment, each write head 200i is assigned in each case three light sources 111±, 112i, 113±, wherein the light from the individual light sources is transferred to the respective write head 200i in each case by means of a single optical waveguide 122i - 122 _N of the associated optical waveguide group 121i. Alternatively, the light from a light source can also be fed to the respective write head 200i by means of a plurality of optical waveguides. In order to obtain a high energy throughput, monomode optical waveguides are preferably used. It is provided that the intensity of the light fed to a write head 200i via an optical waveguide group 121i is individually modulatable for each optical waveguide 122i - 122 _N of the optical waveguide group 121i. In the case where each optical waveguide 122i - 122 _N of the optical waveguide group 121i is assigned in each case one light source 111±, 112i, 113i, this can be carried out by means of an individual control of the respective light source 111±, 112i, 113±. By contrast, if a plurality of optical waveguides 122i - 122 _N are assigned to a common light source 111±, 112i, 113±, the light intensity in the individual optical waveguides 122i - 122 _N can be individually controlled by means of electro- optical modulators 131± arranged in the transfer path between the respective light source 111±, 112i, 113± and the assigned write head 200i. A corresponding modulation device 130 comprising a plurality of electro-optical modulators 131i, 131 ₂ , I3I3 is shown by way of example in Figure 1. For the coordinated driving of the modulation device 130, the latter is connected to the central control device 170 by means of a control line 172. The light generating device 110 is also connected to the central control device 170 by means of a dedicated control line 171 for the purpose of individual driving of individual light sources 111±, 112i, 113± or light source groups comprising a plurality of said light sources llli, 112i, 113i.

In order to generate a suitable writing beam 401± for writing to the substrate wafer 3ΟΟ ₂ , each write head 200i comprises an input coupling device 220 for coupling in the light from the associated optical waveguides 122i - 122 _N of the optical waveguide group 121i assigned to the respective write head 200i, a beam shaping device 230 for shaping a suitable light beam bundle 401 composed of the light beams 400i - 400 _N from the individual optical waveguides 122i - 122 ₂ , a scanning device 240 for producing a scanning movement of the light beam bundle 401, and also an exit optical unit for projecting the generated light beam bundle 401 onto the surface of the substrate wafer 3ΟΟ ₂ to be written to. For controlling the scanning movement of each individual write head 200i, the writing device 140 is connected to the central control device 170 by means of at least one control line 173.

In order that the scanning movement of the light beam bundle 401i, which scanning movement is restricted only to a limited region of the substrate wafer 3ΟΟ ₂ , is converted into a continuous writing movement, the substrate wafer 3ΟΟ ₂ to be written to is moved by means of the transport device 150 in a controlled movement below the writing device 140 in a

predefined transport direction 501. In this case, the

transport device 150 used can be any suitable device with the aid of which a precisely controllable transport movement of one or a plurality of substrate wafers 300 is possible. By way of example, the transport device 150 can be realized in the form of a conveyor belt for continuously transporting a plurality of substrate wafers 300i, 300 ₂ , 3003. For

controlling the transport movement 50, the transport device 150 is connected to the central control device 170 by means of at least one control line 174.

For calibrating individual write heads 200 and monitoring the joint writing process of a plurality of write heads 200i, the lithography apparatus 100 furthermore comprises a specific detection device 160 comprising preferably a plurality of detectors 161±. The detection device 160, which is connected to the central control device 170 via at least one control line 175, captures the position and, if appropriate, also the beam profile of the writing beams 401± of the individual write heads 200i. Such a detection device can be realized in various ways, in principle. In the present exemplary

embodiment, the detection device 160 arranged below the substrate wafer 3ΟΟ ₂ to be written to comprises a plurality of measuring devices 161± having in each case a plurality of specifically arranged photodiodes, said measuring devices being arranged in the writing beams 401± of the individual write heads 200i.

Figure 2 shows by way of example a perspective sectional illustration through the writing device 140 of the

lithography apparatus 100 according to the invention. The writing device 140 comprises a baseplate 141 and a plurality of write heads 200i,j arranged in matrix form and fixed within the baseplate 141. The write heads 200i,j arranged in the form of rows and columns are in this case incorporated vertically in the z-direction in respective opening regions 142

specifically formed in the baseplate 141 and are individually alignable by means of specific holding elements 144 and associated adjusting screws 143. Within the write head arrangement 145 in matrix form, the individual write heads 200i,j are arranged in the form of columns one behind another in the x-direction, which corresponds to the transport direction of the substrate 300, and alongside one another in the y-direction.

Figure 3 shows the internal construction of a write head 200 according to the invention. The write head 200 has a pin- shaped housing 210, in which all the components of the write head 200 are integrated. The substantially cylindrical housing 210 has, shaped at the end, a housing cover 211 having an opening 212 for receiving optical waveguides 122i to 122 _N of an optical waveguide group 121i assigned to the respective write head 200i. In this case, the opening 212 is preferably embodied in a slot-type fashion, such that the optical waveguides enter the write head 200 in a manner arranged alongside one another in the x-direction. In order to efficiently couple in the light from the optical

waveguides 122i to 122 _N , the write head 200 comprises an input coupling device 220, which in the present case

comprises a suitable glass substrate 223 with waveguide structures 224i, 224 _N which are formed therein and are respectively individually assigned to the optical waveguides 122i to 122 _N . For fixing and precisely aligning the optical waveguides 122i to 122 _N , the input coupling device 220 furthermore comprises an optical waveguide receptacle 221, which can comprise for example a glass substrate having

V-shaped grooves 222. The waveguide structures 224 combine the light beams from the individual optical waveguides 122i to 122 _N on the output side to form a narrow light beam bundle. The quality of the focus and the spacing of the beams on the substrate wafer result directly from the arrangement of the waveguides with respect to one another.

The light beams 400 emerging from the input coupling device 220 are subsequently shaped in a desired manner to form a parallel beam bundle in a beam shaping device 230, which comprises a collimator lens 231 in the present exemplary embodiment. The collimator 231 ensures that the exit ends of the light waveguides, which are provided with a certain exit angle, are collimated. The parallel light beams 400i - 400 _N now arranged offset at an angle with respect to one another subsequently pass into a scanning device 240 having at least one scanning mirror 241 for producing a periodic scanning movement of the writing beam 401 on the substrate wafer 300. In this case, the beams meet in a pupil plane, in which the scanning mirror 241 is situated in the case of a one- dimensional scanning device 240. In order to achieve a compact design of the write head 200, the scanning device 240 furthermore comprises further deflection elements 242, 243 in the form of mirrors or prisms, with the aid of which the parallel light beams 400 are aligned again in the z- direction. A particularly compact design of the write head 200 is made possible as a result. Afterward, the parallel light beams 400i - 400 _N fanned out at the scanning mirror 241 leave the write head 200 via a specific exit optical unit 250 (scanning objective lens), which focuses the individual light beams 400i - 400 _N in the form of a converging writing beam bundle 401 onto the substrate wafer. In this case, parallel individual light spots 410i - 410 _N (foci) , arise, which represent a reduced imaging of the exit of the individual waveguides 122i - 122 _N . The parallel individual light spots 410i - 410 _N are guided over the surface 301 of the substrate wafer 300 by the scanning movement.

The exit optical unit 250 preferably comprises a plurality of optical elements 251, 252, 253, 254, which project the collimated light beams 400 deflected by means of the scanning device 240 into a corresponding number of individual light spots 410± - 410 _N , which are focussed on or in the region of the substrate surface 301 and converge to form a total light spot 420, on the surface 301 of the substrate wafer 300 or a light-sensitive layer arranged thereon (not shown here) . In order to generate the most precise possible imaging of the individual light spots 410± - 410 _N on the substrate surface 301, the optical elements 251, 252, 253, 254 can be embodied in the form of a telecentric scanning objective lens and/or in the form of an F-theta lens. From the superimposition of the light spots 410± - 410 _N from the individual optical waveguides 122i to 122 _N , a continuous light spot 420

extending preferably in the x-direction is formed in this way .

With the aid of the input coupling device 220 and the beam shaping device 230, the spatially separate arrangement of the outputs of the individual optical waveguides 122i - 122 _N is converted into a corresponding number of collimated light beams 400i - 400 _N , separated from one another at an angle. In this case the pupil plane of these collimated light beams 400i - 400 _N is formed by the minimum diameter of the

overlapping light beams. In this case, the scanning element 241 is preferably arranged within the pupil plane and

deflects the individual light beams according to their entrance angle. In the case where a plurality of scanning elements are used for a two-dimensional scanning movement, said scanning elements are preferably arranged as near as possible to the pupil plane (not shown here) . In this case, the light beams 400 are deflected preferably in the y- direction, which runs perpendicularly to the plane of the drawing in Figure 3. The scanning movement can be carried out sinusoidally (harmonically) , in this case, wherein the scanning mirror 241 or the respective scanning element oscillates in a resonant fashion. Particularly high scanning amplitudes 433 are possible by this means. Furthermore, a rectangular driving of the scanning mirror 241 or of the scanning element or scanning elements is also possible.

In the present exemplary embodiment, the light from the individual optical waveguides 122i - 122 _N is coupled in by means of a specific input coupling device 220, which is illustrated in greater detail in Figure 4. In the present exemplary embodiment, the input coupling device 220 comprises a flat waveguide substrate 223, in the surface of which a number of waveguides 224i - 224 _N corresponding to the number of connected optical waveguides 122i - 122 _N are formed. Such waveguides can be produced by means of ion diffusion, for example. For coupling the light from the optical waveguides 122i - 122 _N into the waveguides, a receptacle plate 221 is provided, for example a glass plate, in which specifically shaped grooves 222i - 222 _N for receiving the individual optical waveguides 122i - 122 _N are formed. With the aid of the for example V-shaped grooves (V-grooves) the optical waveguides 122i - 122 _N can be precisely aligned and fixed in relation to the waveguides 224i - 224 _N . The receptacle plate 221 can also be embodied integrally with the waveguide plate 223.

The waveguides 224i - 224 _N converge in a bell-shaped fashion on the waveguide plate 223, such that the light beams entering the waveguides over a width 226 on the input side are combined to a significantly smaller output width 227 in the waveguide substrate 223.

As an alternative to the use of waveguides, a bundling of the light beams entering the write head via the optical

waveguides 122i to 122 _n can also be realized with the aid of a microlens arrangement. Figure 5 schematically shows an alternative embodiment of the write head 200 comprising a corresponding microlens arrangement 228. The microlens arrangement 228 comprises a number of microlenses 229i - 229 _N corresponding to the number of entering optical waveguides 122i - 122 _N , by means of which microlenses the outputs of the corresponding optical waveguides 122i - 122 _N are firstly magnified, for example by a factor of 20x. Afterward, the magnified image is reduced to the desired size, for example by the factor l/20x, by means of a telescope 230 comprising the optical elements 231, 232, 233, for example. The

correspondingly shaped light beams 400i - 400 can

subsequently be deflected in a desired manner in a scanning device 240 comprising a scanning mirror 241 or other scanning elements. The deflected light beams 401 are then projected by means of an exit optical unit 250, which is illustrated merely in the form of an exit lens in Figure 5, in a suitable manner onto the surface 301 of the substrate 300 or a light- sensitive layer (not shown here) arranged on the substrate 300, in the form of a light spot 420 composed of a plurality of individual light spots 410i - 410 _N .

Figure 6 shows by way of example the intensity distribution of a light spot 420 composed of a total of ten individual light spots 410i - 410io. The intensity distribution of the individual light spots 410i - 410io is illustrated in each case in the form of a Gaussian curve with an intensity maximum identified by means of a vertical line. The

individual light spots 410i - 410io, preferably arranged at identical distances alongside one another in the x-direction, are superimposed in this case to such an extent that a continuous light spot 420 that is elongate in the x-direction and has a desired width results therefrom. By individual modulation of the light beams 400i - 400 _N coupled into the respective write head 201 by the individual optical

waveguides 122i - 122 _N , the intensity profile of the

composite light spot 420 can be varied arbitrarily. In particular, the width of the composite light spot 420 can be altered by a reduction of the light intensity of the marginal rays. Besides the width variation, by introducing individual light beams on one side and simultaneously masking out individual light beams on the opposite side, it is also possible to realize a lateral displacement of the total light spot 420 generated by superimposition of the individual light spots 410i - 410 _N . These possibilities for variation of the width and the lateral position of the light spot 420 can be used for better control of the writing process on the

substrate. In particular, an improvement of the resolution obtained can be realized by means of the variation of the width of the light spot. Furthermore, distortions which can arise in the image field during operation can also be

compensated for by variation of the line width.

Figure 7 shows by way of example a composite light spot 420 having a total width reduced by the reduction of the light intensity of the outer beams 410i, 4102, 410g, 410io.

As already described in connection with Figure 1, the writing process of a write head 200 is carried out by means of a superimposition of the transport movement of the substrate wafer 300 in the x-direction and a scanning movement 502 of the light spot 420 projected onto the substrate surface 301, said scanning movement being carried out transversely with respect to the transport movement. Figure 8 elucidates the process of writing to a defined strip 430 of the substrate surface 301 by means of the superimposition of the periodic scanning movement 502 and the transport movement 501. The illustration shows a plan view of a region of the substrate surface 301 situated below a write head 200. In this case, the substrate wafer 300 performs the transport movement 501 continuously in the x-direction. In this case, the light spot 420 projected onto the substrate surface 301 simultaneously performs a preferably resonant oscillation movement 502 in a predefined scanning direction 506. In the case of a one- dimensional scanning movement 502, the scanning region 251 that can be captured directly by the light spot 420 is predefined in particular by the width of the light spot 420 and the scanning amplitude 433 in the x-direction. The superimposition of the transport movement 501 and the

oscillation movement 502 results in a substantially harmonic or sinusoidal movement trajectory 504 of the light spot 420 on the substrate wafer 300. In this case, the speeds of the transport movement 501 and of the oscillation movement 502 are coordinated with one another in such a way that the light spot 420 passes at least once every region of the exposed strip 430 of the substrate surface 301, said exposed strip being delimited by means of the dotted lines. Since a substantially sinusoidal exposure pattern is generated in this case, regions exposed to different extents are generally present. If the transport speed 501 of the substrate 300 is too high, adjacent loops of the sinusoidal exposure pattern can be so far apart from one another that specific substrate regions between the loops remain unexposed. In order to prevent this and thus to enable higher transport speeds of the substrate and hence also higher writing speeds, an alternative scanning device having a two-dimensional scanning movement can be used. In the case of this scanning device, besides the periodic oscillation movement carried out

transversely with respect to the transport movement 501, an additional line compensation movement 503 in the x-direction is also carried out. In this respect, Figure 9 shows by way of example an exposure trajectory 505 realized by means of such a 2D scanning device. While the exposure spot 420, on account of the oscillation movement of the scanning mirror 241, still carries out a preferably harmonic oscillation movement 502 in the scanning direction 506, a periodic line compensation movement 503 - carried out in a line

compensation direction 507 transversely with respect to the scanning direction 506 - for compensation of the transport movement 501 of the substrate 300 can be realized with the aid of the same scanning mirror 241 or with the aid of a further scanning element of the write head 200±,j.

Since the amplitude of the compensation movement 503

typically turns out to be significantly smaller than the amplitude 433 of the scanning movement 502, a non- harmonically oscillating scanning element can also be used in this case. Given optimum coordination of the two periodic movements 502, 503 with one another, it is thus possible even to realize a substantially rectangular movement trajectory 505 of the light spot 420 on the substrate 300. As a result of the significantly more uniform exposure of the strip 430 in this case, higher transport speeds and thus higher writing speeds can also be realized by this means in comparison with a scanning device that operates only one-dimensionally .

Both in the case of one-dimensional scanning and in the case of two-dimensional scanning, however, the scanning direction 506 need not necessarily correspond to the y-direction predefined by the lithography apparatus 100, which is the case as in the examples in Figures 8 and 9. Rather, the scanning movement 502 can also be carried out in a direction that deviates from the y-direction. The same also applies to the line compensation direction 507, which corresponds to the x-direction in the present example.

As is shown in detail in Figures 8 and 9, each write head 200i,j of the writing device 140 in each case writes to a dedicated substrate strip 430i,j having a strip width 431 determined by the scanning amplitude 433 of the respective write head 200±,j. For transferring the desired structures into the substrate or in a light-sensitive layer arranged on the substrate, the scanning light spot 420 is switched on and off by modulation of the light sources or of the individual optical waveguides of the respective write head. This can be carried out repeatedly during an up or down movement of the light spot 420 corresponding to half a scanning period 432, depending on the desired resolution. In this regard,

structure widths corresponding to the extent of the light spot 420 in the y-direction can be realized, in principle, in the y-direction. On the other hand, by switching on and off the marginal regions or else the central regions of the light spot 420, it is possible to obtain in the x-direction, too, structure widths corresponding, in principle, to the

dimensions of an individual light spot 410i - 410 _N of which the spot 420 is composed.

The use of a plurality of write heads 200i,j having writing or scanning regions 251 respectively offset relative to one another in the transport direction 501 allows parallel writing to larger continuous substrate areas 450. In this respect, Figure 10 shows a first exemplary embodiment

comprising a matrix-type arrangement of a total of 15 write heads 200±, _j . In this case, the write heads 200i, _j are combined in three columns each having five write heads 200±,ι - 200i,s. In this case, the individual scanning regions 251 of the write heads 200±,ι - 200±,5 are arranged in a manner offset with respect to one another in each case by a maximum of a strip width 431 in the y-direction for example by means of an individual setting of the scanning mirrors 241 of the

respective write heads 200±,ι - 200i,s. This results in strips 430±,i - 430i,5 which touch one another or slightly overlap and which together produce a seamlessly closed area 440±. By means of a corresponding arrangement of the write heads

200i, _j , the strip-shaped areas 440i formed from the write heads 200±,ι - 200±,5 arranged one behind another in each case in the x-direction can be combined seamlessly to form a strip-shaped total area 450.

As an alternative to the offset arrangement of the scanning regions of individual write heads, the write heads 200±,ι - 200i,5 arranged one behind another in the x-direction can also be arranged in a manner offset relative to one another in each case by a strip width 431 in the y-direction, in order to obtain a closed wider strip 440±. A corresponding

embodiment is shown by way of example in Figure 11.

As a result of the total area 450 written to being composed of individual strip regions written to parallel to one another (referred to as stitching) , lithography apparatus for writing to substrate wafers of arbitrary size can be realized in principle. In order to be able to precisely control the distance between the individual strips or their overlap region, the width and position of the individual strip-shaped regions written to must be coordinated with one another. This is particularly important since the components of the

lithography apparatus 100 during operation are subject to various disturbing influences which can influence the writing process of individual write heads differently. In this regard, the scanning regions of adjacent write heads can drift apart for example on account of temperature differences of the corresponding components. Therefore, by way of

example, the detection device 160 already described in connection with Figure 1 is used for calibrating and

monitoring the operation of the writing device 140. Such a detection device 160 can consist for example of one or a plurality of measuring devices 161±,j each having a pair of photodiodes, said measuring devices being installed below the substrate wafer in a positionally fixed manner relative to the respective write head 200±,j. Figure 12 shows by way of example a measuring device 161±,j of such a detection device 160 having two photodiodes 162 and 163 arranged at a

predefined distance from one another. The two photodiodes 162, 163 are fixed on a carrier substrate 164, which

preferably consists of a material having the smallest

possible temperature drift, such as "Zerodur", for example. The measuring device 161±,j can be installed for example in a positionally fixed manner relative to the respectively associated write head 200i,j below the receptacle device 151 of a processed substrate wafer 300. The measuring device 161±,j, initially concealed by the substrate wafer 300 during the writing process, is freed by the further transport of the respective substrate wafer 300 after the end of the writing process. For this purpose, a specific window region 152 between adjacent substrate wafers 300i, 300 ₂ can be provided in the transport direction 150. Each of the two photodiodes 162 and 163 detects in each case the point in time of the passage of the oscillating light spot 420. On the basis of the temporal deviation of the detector signals from a

reference signal, the amplitude 433 and/or lateral position of the scanning region 251 of the respective write head 200i,j can be deduced. For detecting each individual light spot 410i - 410 _N of the composite light spot 420, the measuring device 161±,j can have a corresponding number of pairs of photodiodes arranged closely alongside one another (not shown here) . Such a measuring device 161±,j also enables monitoring or

calibration of the light spot profile of the respective light spot 420, such as e.g. its width and y-position.

Since the detection is carried out in each case for the individual write head, each of the write heads 200i,j used is individually assigned in each case at least one measuring device 161±,j. Figure 13 shows a possible arrangement of a plurality of measuring devices 161±,j of the detector device 160 below a writing device comprising a total of nine write heads 200±,j. The individual measuring devices 161±,j here are arranged in each case exactly below the associated write heads 200i,j, the position of which is indicated here by means of a dashed line. A window region 152 produced between two substrate wafers 300i, 300 ₂ or specifically embodied in the form of an opening in the transport device 150 frees the respective measuring devices 161 after the passage of the substrate wafer 3ΟΟ ₂ that has undergone writing to a finish.

Figure 14 shows an alternative possibility for realizing a corresponding detection device 160. A test substrate 310 having reflective test structures 311, 312 is used in this case. The test structures 311, 312 are arranged here in each case such that when the test substrate 310 passes below the respective write head 200, the incident light beams are reflected back from the test structures 311, 312 into the write head 200. The light 402 reflected back preferably passes via the same optical path to the scanning mirror 241 and is subsequently deflected by a beam splitter 265 to a detecting photodiode 166 or an arrangement comprising a plurality of photodiodes (not shown here) respectively assigned to the individual light beams. Each detector signal is subsequently compared with a corresponding reference signal. On the basis of the comparison result, statements can then be made about the scanning amplitude 433, scanning position and, if appropriate, also about the light spot profile .

Figure 15 shows a corresponding test substrate 310 between two regular substrate wafers 300i, 300 ₂ - In this case, one or a plurality of pairs of such test structures 311, 312 are arranged on the test substrate 310 for each write head 200±,j. In this case, the number and arrangement of the test

structures on the test substrate can be adapted to the respective requirements. As an alternative or in addition thereto, it is also possible for corresponding test

structures also to be arranged on the regular substrate wafers 300i, 300 ₂ (not shown here) . Such test structures can preferably be arranged in regions which are not written to anyway or are specifically provided for calibration.

In order, on the basis of the detector signal of the

photodiodes 161, 162, 166 to be able to make a statement about the amplitude 433 of the scanning movement 502 of the light spot on the substrate wafer and the lateral position of the strip-shaped region respectively written to, the temporal sequence of the respective signals is analysed. In this respect, Figure 16 shows by way of example the relationship between the temporal change in a detector signal and the corresponding variations of the scanning movements. In this case, the upper part of the diagram illustrates the temporal change in the y-position of the light spot 410, 420 carrying out an oscillating movement in various operating situations. In this case, the curve 510 depicted by a solid line

represents the movement of the light spot 420 oscillating with the desired amplitude 433 and in the desired position. The upper horizontal line 513 represents for example the y- position of the first photodiode 162 of the detector device assigned to the respective write head 200, while the lower horizontal line 514 represents the y-position of the second photodiode 163. In the case of the alternative detection device, the horizontal lines 513, 514 in each case represent the y-positions of the two test structures 131, 132 of the respective write head 200. The points of intersection of the individual curves 510, 511, 512 with the two horizontal lines 513, 514 correspond in each case to the passing of the scanning light spot 410, 420 over one of the photodiodes 162, 163 or test structures 131, 132. These events define the points in time of the associated excursions of the respective detector signal. The lower region of the diagram illustrates the profiles of the three detector signals 515, 516, 517, that are respectively assigned to one of the three curves 510, 511, 512. In this case, the second curve 515 shows the profile of the detector signal for the "regular" scanning process represented by means of the solid line. In this case, the detector signal exhibits a specific regular pattern that can be used as a reference signal for the other operating situations. In this regard, an increase in the scanning amplitude 433, as is the case for the curve 511 shown by means of the dashed line, has the effect that the signal excursions of the two photodiodes 162, 163 are shifted symmetrically with respect to one another. This is evident in the second detector signal profile 516 by a comparison with the reference signal.

By contrast, if the position of the exposed strip drifts along the y-direction, as is the case for example for the curve 512 shown by means of the dash-dotted line, then the corresponding detector signal 517 exhibits an asymmetrical shift in the signal excursions of the two photodiodes 162, 163.

As already described in connection with Figures 8 and 9, the scanning movement of the light spot for writing to the respective substrate strip can be carried out both one- dimensionally and two-dimensionally . In the case of the two- dimensional scanning movement, it is necessary for the line compensation movement carried out in the transport direction of the substrate to be precisely coordinated with the scanning movement carried out transversely with respect to the transport direction of the substrate. This is achieved in particular by means of two micromechanical mirrors that are controllable independently of one another. In contrast thereto, in the case of the one-dimensional scanning

movement, only one scanning mirror is required, as a result of which the outlay on apparatus is significantly reduced in comparison with the two-dimensional scanning movement.

However, a harmonically oscillating scanning mirror without a corresponding line compensation movement produces a

sinusoidal trajectory of the light spot on the substrate moving underneath. On account of the sinusoidal form, the trajectory in the regions of the upper and lower turning points deviates very greatly from a straight line.

Furthermore, at the turning points the speed of the light spot decreases in comparison with the central scanning region. Consequently, the residence duration of the light spot increases in the region of a turning point. In the case of an illumination intensity kept constant over the entire period, an increased residence duration and the curved trajectory would lead to significantly more highly exposed outer regions of the strip written to by the respective write head. This can be prevented in various ways. By way of example, the oscillation amplitude of the scanning mirror can be chosen to have a magnitude such that the upper and lower turning regions of the sinusoidal trajectory of the light spot lie distinctly outside the strip to be written to. By means of suitable shading or by means of switching off the light source in the upper turning regions, it can be ensured that the illumination takes place only within the strip- shaped substrate region. Such an arrangement is illustrated schematically by way of example in Figure 17. As is evident here, the upper and lower turning points of the sinusoidal trajectory 504 lie outside the strip 430 to be exposed. The central regions of the movement trajectory 504, which are arranged within the strip 430, run approximately linearly here. One disadvantage of this concept is that on account of the overshoot of the movement trajectory outside the strip 430 to be exposed, the write head has relatively long dark phases in which no exposure of the substrate within the strip 430 takes place. This results in a lower throughput overall. An increase in the throughput can be achieved by a reduction of the dark phases of the movement trajectory 504. For the same light intensity, the same substrate speed and the same scanning frequency, a reduction of the scanning amplitude leads to a longer residence duration of the light spot above the regions of the substrate that are to be written to. The lower writing speed resulting therefrom leads to an increase in the light dose per unit area. A corresponding schematic illustration of a scanning movement with reduced dark phases is illustrated in Figure 18.

On account of the geometry of the sinusoidal trajectory 504 and the reduced speed of the light spot 420 in the regions of the turning points 508, 509, the residence duration of the light spot 420 on the substrate surface 301 is significantly higher in the marginal regions 434, 436 of the strip 430 than in the central region 435. Given constant light power of the write head, the marginal regions 434, 436 of the strip 430 would therefore be exposed to a significantly greater extent than its central region 435. In order to obtain a homogeneous exposure of the entire strip 430, it is thus expedient to vary the light intensity of the light spot 420 or of the light beams 410i - 410io forming the light spot 420 in a manner dependent on the position thereof along the scanning direction y. By way of example, in the case of a pulsed light source, both the switch-on and the switch-off phases of the light source can be varied jointly or independently of one another. Furthermore, the intensity of the light spot 420 can be varied by modulation of the light source or of a light- guiding element disposed downstream of the light source, such that the intensity of the light spot turns out to be lower in the outer regions 434, 436 of the strip 430 than in the central region 435 thereof. In order to obtain a homogeneous illumination, in this case, both the duty ratio and the light intensity of the individual light spots 410 forming the light spot 420 can be varied both jointly and independently of one another. In this regard, by way of example, individual light spots 410 of the total light spot 420 can be switched off separately in order to reduce the light intensity. As an alternative thereto, the light intensity of individual light spots 410 of the total light spot 420 can be modulated in a suitable manner.

By means of a suitable intensity variation of individual light spots 410 or of the entire light spot 420, a

homogeneous illumination over a plurality of scanning periods can thus be achieved even in the case of a sinusoidal

movement trajectory 504.

In order to achieve a homogeneous exposure of the substrate surface, the intensity of the light beams 400 that generate the individual light spots 410 must be varied in a predefined manner. This results in a specific exposure pattern in which the arrangement of the individual light spots on the

substrate turns out to be relatively complex on account of the sinusoidal movement trajectory. In order to be able to write structures on the substrate surfaces, the contours of the respective structures have to be transferred to the exposure pattern. On account of the abovementioned complexity of the exposure pattern, the transfer of the structures to be written is relatively computationally complex.

In order to simplify this method step, the complex exposure pattern can be decomposed into two separate partial exposure patterns. For this purpose, all light spots which lie on the falling edges of the sinusoidal movement trajectories of the respective light spots are combined to form a first partial exposure pattern 520. In a manner corresponding thereto, all light spots which lie on the rising edges of the sinusoidal movement trajectories of the respective light spots are combined to form a second partial exposure pattern 530. The desired structures are subsequently transferred separately into each of the two partial exposure patterns 520, 530.

Since the desired structures are impressed congruently in each of the partial exposure patterns 520, 530 the structures to be written are optimally reproduced in the total exposure pattern arising as a result of the superimposition of the two partial exposure patterns 520, 530 during the writing

process. Figure 19 schematically illustrates the first partial exposure pattern 520, which contains all the switch- on phases of the individual light spots 410i to 410io of a total light spot 420 during the movement from an upper turning point 508 to a lower turning point 509. In this case, the corresponding portions of the movement trajectories 521i - 521io of the light spots 410i - 410io are represented by means of dotted lines. In this case, the individual light spots 410i to 410io are each represented by means of dashed lines, wherein the respective midpoints of the light spots are represented by means of small circles 411. For the sake of clarity, only the topmost and bottommost light spots 410i to 410io are represented by means of the dashed circles.

Furthermore, only the light spots and the associated

trajectories during an individual scanning movement from the upper turning point 508 to the lower turning point 509 have been illustrated, for reasons of clarity. As indicated by means of dots in the drawing, the first partial exposure pattern 520 is typically composed of a sequence of such portions like the portion illustrated in Figure 19. In this case, the individual portions can be superimposed to a greater or lesser extent depending on the application.

Analogously to Figure 19, Figure 20 illustrates the second partial exposure pattern 530, which corresponds to the distribution of the exposure spots on the substrate surface which are generated during in each case half a scanning period in the course of the movement of the light spot from the lower turning point 509 to the upper turning point 508.

Although the invention has been more specifically illustrated and described in detail by means of the preferred exemplary embodiment, nevertheless the invention is not restricted by the examples disclosed, and other variations can be derived therefrom by the person skilled in the art, without departing from the scope of protection of the invention.

List of reference signs

100 Lithography apparatus

110 Light generating device

111-119 Light sources

120 Light transferring device

121 Optical waveguide group

122 Optical waveguide

123 Diameter of an optical waveguide

130 Modulation device

131 Electro-optical modulator

140 Writing device

141 Baseplate

142 Opening in the baseplate

143 Adjusting screw

144 Holding element

145 Write head arrangement in matrix form

150 Transport device

151 Receptacle device

152 Window region between two receptacle devices

160 Detection device

161 Measuring device

162, 163 Photodiodes

164 Carrier substrate

165 Semitransmissive mirror

166 Internal photodiode

170 Control device

171 First control line

172 Second control line

173 Third control line

174 Fourth control line

175 Fifth control line

200 Write head

210 Housing

211 Housing cover

212 Slot-shaped housing opening 220 Input coupling device

221 Receptacle plate

222 Centring device/V-grooves

223 Waveguide substrate

224 Waveguide

225 Waveguide exit facets

226 Input width

227 Output width

228 Microlens arrangement

229 Microlens

230 Optical device/beam shaping device

231- ^■ 233 Lenses of the beam shaping device

240 Scanning device

241 Scanning mirror

242,243 Deflection elements

244 Scanning axis

250 Exit optical unit

251 Scanning region

251- ^■ 254 Lenses of the exit optical unit

300 Substrate wafer

301 Substrate surface

310 Test substrate wafer

311,312 Reflective test structures

400 Light beams

401 Writing beam bundle

402 Reflected light beams

410 Individual light spot of a light beam

411 Centre of an individual light spot

420 Light spot composed of individual light spots

430 Strip exposed by the light spot

431 Width of the strip

432 Scanning period

433 Amplitude of the scanning movement

434 Upper marginal region of the exposed strip

435 Central region of the exposed strip

436 Lower marginal region of the exposed strip

440 Group of strips written to 450 Exposed total area

500 Coordinate system

501 Transport movement

502 Periodic scanning movement

503 Periodic line compensation movement

504 First movement trajectory

505 Second movement trajectory

506 Scanning direction

507 Direction of the line compensation movement

508 Upper turning point

509 Lower turning point

510 First trajectory

511 Second trajectory

512 Third trajectory

513 Position of the first photodiode/test structure

514 Position of the second photodiode/test structure

515 First signal curve

516 Second signal curve

517 Third signal curve

520 First partial exposure pattern

521 Falling edge of the movement trajectory

530 Second partial exposure pattern

531 Rising edge of the movement trajectory

x x-direction/transport direction

y y-direction/scanning direction

z z-direction (vertical direction)

I Light intensity

A Amplitude of the detection signal