Exposure control in photolithography direct exposure processes for circuit board or circuit manufacturing

Abstract

The present invention relates to an apparatus for exposure control in a photolithography direct exposure method for two-dimensional structures in a photosensitive coating, as well as a method for converting recorded data into direct exposure data. The objective of finding improved exposure control in a direct exposure method for two-dimensional structures in a photosensitive layer, which allows alignment of target marks regardless of their defined positions, is achieved in accordance with the present invention by arranging a plurality of non-eccentric cameras in an alignment unit (1) to form a gap-free linear scanning area (23) aligned linearly transversely to the one-dimensional movement of the substrate (2) across a predetermined width of the substrate (2). The image angles of adjacent entocentric cameras along the linear scanning area (23) have overlapping areas where redundant image recordings of the substrate (2) from adjacent cameras are detectable, and the computer unit (5) has means for calculating the positions of the target marks from the redundant image recordings of the adjacent entocentric cameras, further using the height positions of the target marks determined by triangulation of the spacing of the substrate surface (21).

Description

[Technical Field]

[0001] The present invention relates to an exposure control device for photolithography direct exposure methods for photosensitive coatings, preferably two-dimensional structures on circuit boards, display substrates or wafers, and a method for converting recording data into direct exposure data, in particular for recording on a textured substrate and adapting its implementation as a result of the recording "on the fly." "On the fly" recording means that the position data of the target marks, and thus the position of the substrate to be processed and its texture, are detected directly and continuously during the substrate's continuous movement and are used to align the exposure pattern to the substrate by adapting the exposure data for the subsequent direct exposure. The application fields of the invention are in the electronics and semiconductor industries, particularly in printed circuit board manufacturing, display manufacturing and chip manufacturing. [Background technology]

[0002] The prior art is known for exposure systems for disk- or plate-shaped workpieces, which can expose the exposure object with a predetermined pattern using electromagnetic radiation, primarily in the visible or ultraviolet spectral range, using a laser beam or an electron or particle beam. In this case, exposure can only proceed after the correct positional relationship between the exposure object, on which a mark (target mark or target) is located, and the predetermined pattern stored in the exposure device has been established. For this purpose, the target mark present on the exposure object is detected by one or more cameras, and the exposure object and the exposure pattern are aligned relative to each other before or during the exposure area.

[0003] For the production of conductor tracks or smallest electronic structures on plate-like substrates such as printed wiring boards, display substrates, or wafers, the exposure process, which must be performed with high spatial precision, and the handling and alignment times of the plate-like workpieces required for this, are limiting factors for increasing throughput. Therefore, it is desirable to perform the handling and exposure steps overlappingly or simultaneously, thereby reducing the exposure process sub-time within the same apparatus for the desired exposure of the front and back sides. Such solutions are disclosed, for example, in documents EP 0951054, EP 072223, U.S. Pat. No. 6,806,945, and JP 2010-181519 A1.

[0004] Another challenge in the direct exposure method is to enable alignment regardless of the type, number, and position of target marks (targets) on the exposure object and height variations on the object surface.

[0005] A solution for detecting surface topography is known from WO 2016 / 115536 ​​A2, in which a known two-dimensional pattern projected or otherwise applied to a surface is recorded two-dimensionally with the surface, and the three-dimensional shape of the surface is determined based on distortion of the pattern due to surface irregularities. However, due to limited resolution, this method is not suitable for detecting irregularities with little difference.

[0006] EP 0954768 describes an apparatus for focusing on the surface of a semiconductor wafer, in which the actual surface topography of the semiconductor wafer is recorded before exposure in an exposure device. For this purpose, the surface is detected as height information in a planar manner by a distance sensor, and periodic height variations are then determined and stored. Based on the determined periodic height variations, an optimized focus position for the exposure optics is determined for the partial region of the wafer surface to be exposed, and the wafer is aligned accordingly. Disadvantages include the time-consuming acquisition of height information by the distance sensor and the subsequent alignment of the wafer.

[0007] Another alignment control technique for direct laser exposure of substrates, particularly multilayer PCBs (printed circuit boards), is disclosed in WO 03 / 094582 A2, in which a digital control image is generated by non-uniformly correcting a representation of an electrical circuit so that the electrical circuit pattern applied to the substrate by using the digital control image precisely matches the already existing circuit portion. To this end, selected reference marks are recorded on the existing actual structure, and the target structure to be exposed is corrected based on the deviation between the actual position and the target position in the spatial direction, so that exposure is carried out with a corrected scanning grating. Because a camera present in the exposure head is used for recording, each reference mark must be approached by a relative movement between the substrate and the scanning head.

[0008] German Patent Application Publication No. 10 2018 13 001 A1 discloses an apparatus for processing plate-shaped workpieces with a high workpiece throughput for use in direct exposure of printed circuit boards. In this apparatus, a recording unit is provided with two or three surface cameras movable transversely to the movement of the printed circuit board to detect target marks when the positions of the target mark locations on the printed circuit board are known in advance. The cameras, positioned parallel to the processing path, are alternately arranged to align the circuit board with two tables moving on the same rail system, also positioned parallel to the processing path, thereby minimizing the cycle time for processing the circuit board by shortening processing and auxiliary times. In this case, the cameras are typically positioned in the edge area of ​​the printed circuit board or above the circuitry of the printed circuit board, where the target marks are expected, as is known. Detection of arbitrarily positioned target marks, which is increasingly required on circuit boards and wafers, is only possible at a reduced throughput due to the necessary camera shifts, and height variations on the substrate surface cannot be detected.

[0009] EP 2 775 349 A1 describes a method for determining the correct focus position in an inspection optical system, in which the difference between the focus position of the inspection system and the position of the object to be inspected is determined, and an image of the object is captured regardless of the correct focus position. Based on the characteristics of the captured image, an algorithm of the inspection system can estimate the magnitude and direction of the deviation between the focus position and the object position by adapting the object position to the focus position of the inspection system according to the difference and direction. In the described method for microscopically inspected samples in which different characteristic objects are found that may have different spatial extents and therefore significant height differences in the observed surface, a specific adaptation of the focus position is necessary to enable the different objects to be clearly detected. In this case, height profiles are not detected over the entire surface.

[0010] U.S. Patent Nos. 6,245,585 B1 and 6,449,029 B1 describe a method and apparatus for adjusting the focus position during photolithography of semiconductor wafers. Prior to exposure, the surface height in the z-direction of each subsection of the wafer to be exposed is measured. The subsections are rectangular and arranged in a grid pattern, which are sequentially exposed. Reflections of five obliquely incident laser beams are detected on the surface of each subsection, one directed toward the center of the subsection and four directed toward one of the corners of the subsection. From the reflection positions, an offset value, by which the height position of each subsection deviates from the reference height, can be determined, and the surface angle can be calculated for each subsection. Prior to exposure of each subsection, the wafer is aligned according to stored values. This alignment is performed using individually controllable actuators that adjust the height and angle. However, for each subsection, only an average correction can be set across the entire subsection.

[0011] Unpublished German patent application No. 102019128198.9 describes an apparatus for introducing a pattern into a wound-up endless substrate using radiation, in which the alignment of target marks and the pattern exposure take place on the endless substrate, which is tightly guided by a processing drum. If the recording unit and the processing unit are diametrically opposed on the drum, the change in height of the substrate due to the drum curvature can be used to adapt both the focusing of the camera of the recording unit and the focusing of the processing beam by moving the drum longitudinally relative to the substrate movement direction. However, measuring the amount of defocusing requires additional auxiliary means by which the absolute position of the substrate surface can be determined.

[0012] U.S. Patent Application Publication No. 2004 / 0223129A1 discloses an exposure apparatus for planarly exposing a photosensitive material, in which the photosensitive material is moved in a plane relative to the exposure apparatus, which has multiple identical exposure heads arranged in a matrix. Each exposure head modulates light from a light source into a two-dimensional pattern, which is then projected onto the material surface using a telecentric optical system for exposure. To compensate for irregularities at various positions on the material surface, each exposure head has a pair of wedge prisms in its beam path. The wedge prisms adjust the optical length between the objective lens and the material surface when a distance sensor based on a reflected laser beam detects irregularities based on the changed position of the material surface. A drawback of this method is the individual tracking of each exposure head and its image field as an individual image segment, which can lead to abrupt changes in the imaging scale between adjacent image segments. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] European Patent Application Publication No. 0951054 [Patent Document 2] European Patent No. 072223 [Patent Document 3] U.S. Patent No. 6,806,945 [Patent Document 4] Japanese Patent Application Laid-Open No. 2010-181519 Summary of the Invention [Problem to be solved by the invention]

[0014] The aim of the present invention is to find new possibilities for improved exposure control in direct exposure methods for two-dimensional structures in the photosensitive layer of printed circuit boards or wafers, which allows on-the-fly recording of target marks independent of their defined position and avoids the use of expensive telecentric objectives. An extended aim is to achieve flexible adjustment of the exposure pattern also to determined irregularities of the substrate. [Means for solving the problem]

[0015] An apparatus for controlling exposure in photolithographic direct exposure of two-dimensional structures in a photosensitive coating on a substrate comprises an alignment unit for aligning target marks located on the substrate surface and a movable table system for supporting and defining one-dimensional movement of the substrate below the alignment unit. The apparatus also comprises a processing unit having a controllable linear processing path for photolithographic processing of the substrate with a processing beam to introduce the two-dimensional structures, and a computer unit for controlling the alignment between the processing path and the substrate by local adjustment of the photolithographic processing in accordance with the position of the substrate determined by the aligned target marks. According to the present invention, the above object is achieved by arranging multiple entocentric cameras in a linear array across the one-dimensional movement of the substrate, forming a gapless linear scanning area across a predetermined width of the substrate and having a field of view extending in the direction of the linear scanning area, in order to detect redundant image capture of the substrate by adjacent cameras within the overlapping area. The computer unit has means for calculating the position of the target mark from redundant imaging in the overlap region (13) of adjacent entocentric cameras, additionally using the height position of the target mark determined by triangulation of the distance on the substrate surface.

[0016] The alignment unit advantageously comprises a plurality of entocentric cameras for generating linearly successive gapless sensor areas having overlapping areas as large as at least half the angular fields of view of adjacent cameras, and the computer unit is adapted to determine, by triangulation of distances at any position on the substrate surface, target marks located anywhere across the width of the substrate, independently of the positions of the target marks inside the gapless successive overlapping areas of the angular fields of view of adjacent entocentric cameras.

[0017] The camera is preferably a line camera so that the linear scan area is narrow and tightly packed, with an overlap area across the full width of the substrate via a camera with a long scan length.

[0018] The cameras are preferably aimed at the substrate surface with their optical axes parallel to one another, and the overlapping areas of the angular fields of all the cameras are of equal size.

[0019] In another advantageous configuration, two adjacent cameras are directed at the substrate surface with optical axes tilted relative to each other, and the overlap region of the angle of view of the cameras tilted relative to each other is adjusted so that the angle of view of the two cameras completely overlap on the substrate surface.

[0020] The overlapping region formed by the cameras tilted relative to each other in a pair is adjacent to at least one further overlapping region without a gap until the overlapping region has an extension corresponding to at least the width of the substrate. An overlap can be provided between the pair of cameras tilted relative to each other to ensure a gap-free scanning region of the recording unit for all allowable height variations Δz of the substrate surface. The cameras tilted relative to each other in a pair are preferably arranged so as to be subjected to a Scheimpflug condition.

[0021] In an advantageous configuration of the invention, the computer unit further comprises a control for fast focus tracking of the processing unit along the processing path in response to height variations Δz of the substrate surface, which includes triangulation of a target mark or any imaging structure on the substrate surface based on redundant image capture in overlapping areas of adjacent entocentric cameras.

[0022] In a further preferred variation, the alignment unit has only two entocentric cameras for detecting the target marks, and these cameras are arranged on a scan line transverse to the direction of movement of the substrate, with an overlap area of ​​1 / 100 to 1 / 3 of the camera's angle of view when the substrate, such as a flexible continuous substrate, is guided taut on the rotary table system without height fluctuation Δz. The overlap area of ​​the two cameras' angles of view is configured so that triangulation can be applied to accurately determine the thickness of the substrate in the overlap area of ​​the angle of view on the rotary table system and can be assumed to be constant across the entire width of the rotary table system.

[0023] Preferably, the alignment unit further comprises a light source for illuminating the linear gapless scanning area, the light source being configured for continuous illumination and having a configuration for controlling at least one characteristic including brightness, angle of incidence, or spectral range, and arranged to be uniformly distributed within the housing to achieve a scan line that is uniformly illuminated by dark field illumination or bright field illumination.

[0024] Furthermore, the light source can be adapted for continuous illumination to enable image capture by controlling the integration time of the sensor lines by means of an electronic shutter principle.

[0025] In a further preferred configuration of the present invention, focus tracking for height variations Δz of the substrate is incorporated into the processing unit, in which the height variations Δz determined by the computer unit by triangulation from images redundantly captured by two adjacent cameras of the recording unit can be adjusted in real time by high-speed focus correction for each image point of the recording unit, and the focus tracking can be controlled based on changes in lens position, mirror position or mirror curvature.

[0026] Focus tracking is advantageously controllable based on changes in the mirror curvature at least in a lateral direction x relative to the substrate movement direction y. Focus tracking may preferably be separately controllable based on changes in the mirror curvature in the substrate movement direction y and in the lateral direction x. In a preferred embodiment, focus tracking is controllable by changes in the mirror curvature by a piezoelectric element.

[0027] Focus tracking can advantageously be applied based on changes in lens position or mirror position or mirror curvature to correct image-dependent focus deviations of upstream focusing optics or other upstream optical elements resulting from optical design or optical fabrication.

[0028] The above problem is solved by a method for controlling exposure in direct photolithographic exposure of a two-dimensional structure in a photosensitive coating on a substrate, the method comprising the steps of:

[0029] In an alignment unit for detecting a target mark disposed on a substrate, a step of arranging a plurality of entcentric cameras to form a gapless linear scan area transverse to a movement direction of the substrate, the entcentric cameras having a field of view extending along an overlap area and the linear scan area formed by adjacent entcentric cameras to obtain redundant image captures of the substrate in the overlap area from the adjacent cameras; moving the substrate on a movable table system in a defined one-dimensional movement below the recording unit; providing a processing unit for photolithographic fabrication of two-dimensional structures using a controllable processing beam along a linear processing path; detecting the spatial positions relative to length, width and height of target marks randomly distributed across a given width of the substrate during a single pass of the substrate through a linear scanning area of ​​the recording unit; determining the positions of target marks randomly distributed across the width of the substrate from redundant imaging of the overlapping regions of adjacent entcentric cameras, additionally using height positions of the target marks determined from the redundant imaging of the adjacent entcentric cameras by triangulation of distances on the substrate surface; a processing unit calculating data for alignment and local adjustment of processing of a substrate having a two-dimensional structure to control a processing beam along a linear processing path directed transverse to a direction of movement of the substrate; Controlling the alignment between the processing path and the substrate and local adjustments of the photolithography process according to the position of the substrate determined by the aligned target marks.

[0030] In a variant of the preferred method, the calculation of the spatial positions of the target marks, arbitrarily distributed over the width of the substrate, is extended based on their height positions for triangulation of further detectable structures of the substrate in redundant images captured in overlapping areas during the passage of the substrate, and fast focus adjustment of the focus of the processing beam is performed by focus tracking along the processing path based on control of lens position or mirror position or mirror curvature.

[0031] The fast focusing of the focal point of the processing beam is advantageously carried out at a frequency that is at least 2 to 3 times higher than the conventional scanning frequency of the processing beam.

[0032] The present invention is based on the fundamental consideration that one or more cameras (e.g., CCD cameras, CMOS cameras) equipped with a telecentric objective lens and having a two-dimensional sensor positioned precisely vertically above a defined portion of the substrate are used in the recording system. Therefore, even if the focal position of the objective lens shifts relative to the substrate due to changes in thickness or topography, the detected position remains constant within the available focal depth of the telecentric camera. For structural reasons, telecentric objective lenses are relatively expensive and very bulky, so the mechanical dimensions of the objective lens must always be larger than the image field to be captured. Therefore, telecentric objective lenses do not enable gapless image capture by multiple cameras positioned along a straight line; rather, they must be positioned offset along multiple parallel lines for this purpose. Furthermore, specific determination of substrate height deviations, which is of considerable importance for high-precision determination of target mark positions and accurate alignment and adjustment of exposure patterns, is not possible.

[0033] The present invention solves these problems by combining a type of line image scanning (hereafter referred to as FPSS [Full Panel Scan System]) across the entire substrate width during gradual relative movement between the substrate and the linear scan area using cameras with entocentric objective lenses. The field angles overlap to the extent that triangulation of height differences is possible from multiple camera images from different cameras for each substrate position in the linear scan area. Alternatively, a defined arrangement of multiple cameras positioned obliquely relative to the substrate allows complete overlap of the field angles of two adjacent cameras while complying with the Scheimpflug condition, thus enabling triangulation for each substrate position in the linear scan area from only two camera images.

[0034] The definition of "field angle" in the present invention is taken from the field of photography. Therefore, the field angle is understood as the angle in the object space limited by the edges of the camera format (in this case, the camera of the recording unit). Therefore, in this case, the field angle is determined by the height and width of the camera format (as opposed to the diagonal, which is also often used and specifies the maximum field angle independent of the actual used aspect ratio of the camera format). The camera format is predetermined by the sensor format, and therefore the object field of view (FOV) is defined as the object space defined by the horizontal and vertical field angles via the objective lens imaging.

[0035] Apart from the image format - the height H and width B of the camera format - the angle of view is essentially determined only by the actual focal length f of the objective. However, the focal length f can only be used to directly define the angle of view when the objective is adjusted to "infinity" (object-side telecentric objective). When imaging an object at a finite object distance (short object distance), the image distance b is greater than the focal length f, resulting in a horizontal angle of view of the camera format width B as follows: α=2·arctan[B / (2·b)] (1)

[0036] When using a line camera, the horizontal field of view according to equation (1) is the deterministic field of view of the camera due to the substantially linear sensor format, and can therefore be used by itself to define a linear object field of view.

[0037] The height deviation of the substrate, determined by the entocentric camera along the scan line by local triangulation, can be used not only for precise two-dimensional alignment of the target marks, but also for point-accurate tracking of the focal position of the processing beam, which moves linearly along the processing path. Tracking of the processing beam along the processing path for normal alignment of the exposure pattern with the recorded target mark positions can be additionally supplemented by an adjustment mechanism for fast focus changes of the processing beam based on the detected height variations. Focus changes must be performed at a frequency at least 2-10 times higher than the normal scanning frequency of the processing beam (0.5-1 kHz for polygon scanners) and therefore must be controllable by simple linear position changes or by changing the radius of curvature of lenses or mirrors.

[0038] The present invention realizes new possibilities for improved exposure control in direct exposure processes for two-dimensional structures in photosensitive layers on printed circuit boards or wafers, which allows "on-the-fly" alignment of target marks by linear scanning fields independent of fixed spatial specifications of the target marks relative to a defined exposure field, avoiding the use of expensive telecentric objective lenses, and allowing flexible alignment and adjustment of the exposure pattern to determine the unevenness of the substrate. [Brief explanation of the drawings]

[0039] The present invention will now be described in detail with reference to the following examples and drawings, in which: [Figure 1] Schematic diagram of a recording unit for target mark detection, the recording unit for target mark detection being formed as a multi-camera arrangement, which includes a linear arrangement of non-eccentric cameras with overlapping image areas to obtain a linear scanning range across the complete object width transverse to the object motion. [Figure 2]1 is a schematic diagram of a recording unit configured as a multi-camera configuration, in which a linear arrangement of cameras is formed with pairs of tilted entcentric cameras that satisfy the Scheimpflug condition and have pairwise completely overlapping image fields. [Figure 3] FIG. 1 is a schematic diagram for achieving the orientation of an off-center camera under Scheimpflug conditions. [Figure 4] 1 is a schematic perspective view of two selected time-sequentially executed line scans of a recording unit and a resulting diagram of the height variation of an object along the two selected line scans. [Figure 5] Schematic of the triangulation method used for height measurement in the overlapping area of ​​two adjacent non-eccentric cameras. [Figure 6] Schematic illustration of the invention in a side view transverse to the object movement direction showing an enlarged view of the height variations of the substrate surface, in which a recording unit is connected to the processing unit via a computer unit in order to convert the height measurements made by triangulation into a point-precise control of the focus in the processing beam scanned perpendicular to the drawing plane. [Figure 7] 1 is a schematic perspective view of the invention with recording and processing units transverse to the substrate movement direction on an endless substrate tautly guided on a rotary table system; FIG. [Figure 8] FIG. 10 is a schematic diagram for realizing focus control of a focus tracking unit using a movable objective lens. [Figure 9] FIG. 1 is a schematic diagram for implementing focus control for the current focus tracker with a fixed angle mirror and a movable retroreflector. [Figure 10] FIG. 1 is a perspective view of an elastically bendable mirror element that changes mirror curvature with a linear actuator. [Figure 11] FIG. 11 is a schematic diagram of the bendable mirror element of FIG. [Figure 12] 11 is a schematic diagram of a focus tracking unit having one elastic mirror element of FIG. 10 for mirror control separately in the direction of substrate movement and in the lateral direction. DETAILED DESCRIPTION OF THE INVENTION

[0040] In an advantageous basic variant according to Fig. 1, the alignment unit 1 according to the invention comprises a number of cameras 11 forming a linear arrangement in which their optical axes 111 in the plane of the substrate 2 are oriented along a line transverse to the direction of movement of the substrate 2 being guided past them (scanning line 23 is only shown in Figs. 1, 4 and 6). The width of the substrate being guided past is then completely covered by the field of view 112 or linear field of view of the cameras 11, which at least partly overlap one another. This is possible because the objective lenses 15 are entocentric rather than telecentric. Furthermore, the camera 11 as a line camera has one or several sensor lines 114 arranged in parallel.

[0041] The arrangement of the cameras 11 with individual sensor lines 114 (so-called line cameras, not shown in FIG. 1 ) is scalable, i.e., any required scanning width can be achieved by combining multiple cameras 11. The exact position of the target mark 22 can only be determined in the overlap region 13 of the field of view 112 of the two cameras 11. The non-overlapping region is not subject to accurate measurement, and only half of the field of view 112 of the camera 11 can be used in the edge region of the substrate 2, as long as the overlap region 13 is limited to half the field of view 112. Therefore, only half the field of view 112 of the camera 11 is shown in FIG. 1 for the camera 11 in the edge region of the substrate 2.

[0042] The recording unit 1 is oriented with an elongated housing 12 transverse to the direction of movement of the substrate 2 to be scanned relative to a target mark 22 (shown only in FIGS. 2 and 7 ), which is guided underneath and through the recording unit 1 on a table system 3 (shown only as a support surface). As can be seen from the side view in FIG. 1 , the recording unit 1 has concentrated illumination means at a short distance from the substrate surface 21. The illumination means is configured as a light source 17 whose illumination light illuminates only the substrate 2 without directing light in the direction of the camera 11; the illumination can be under different oblique angles of incidence (dark-field illumination) and possibly in different spectral colors. Alternatively, the light of the light source 17 can be directly coupled into the recording beam path of the camera 11 as bright-field illumination (not shown).

[0043] The camera configuration selected in FIG. 1 includes five cameras 11 with optical axes 111 aligned parallel to one another and a relatively large overlapping region 13 of the cameras 11 corresponding to half the angle of view 112 of each camera 11. In this way, a gap-free, substantially linear scan across the entire width of the substrate 2 is achieved, making it possible to detect all target marks 22 located along the substrate width in a single scan without mechanical camera movement when the substrate 2 is moved laterally as indicated by the arrow in the side view of FIG. 1 shown on the right. The substantially linear scan is realized by the alignment unit 1 in that it includes cameras 11 in the form of line cameras. To generate a linear scan region transverse to the direction of movement of the substrate 2, the entocentric cameras 11 must be aimed at the substrate surface 21 with their optical axes 111 in a plane (not shown) above the scan line 23 (shown only in FIG. 2 ) so that their angles of view 112 overlap thereon, forming an overlapping region 13 along the scan line 23.

[0044] For typical substrate widths of 500-635 mm, an entocentric camera 11 (in the form of a line camera) with a scanning length of 330 mm in the focal region can be used for the currently required resolution (8-12 μm / pixel on the substrate 2), so that a recording unit 1 with five cameras 11 can completely cover the entire width of the substrate at a distance of 165 mm in the direction of the optical axis 111 of the cameras 11. Each position on the scanning line 23 of the substrate width (lateral dimension of the substrate 2) is acquired simultaneously and overlappingly in two different camera images of adjacent cameras 11. In this example, the five cameras 11 directed on the scanning line 23 have a total scanning length of 660 mm, which exceeds the currently maximum substrate width (635 mm) by 25 mm. Due to the additional slight overlap 14, they can be positioned close to each other to ensure a gap-free double scanning even in the case of positioning or mounting tolerances of the cameras 11 and / or height variations Δz of the substrate 2. Therefore, within the overlap region 13, reliable scanning beyond the edge region of the substrate 2 is possible.

[0045] 1, a scanning area that is actually linear and has a length / width aspect ratio of more than 2000 can be scanned along the scanning line 23. The recording unit 1 can generally have a scanning line 23 with a length / width aspect ratio of more than 1000 to 100,000. The scanning width in the movement direction y of the substrate 2 can be adjusted by electronic control (synchronization) of the readout mode and speed of the camera 11 by the computer unit 5.

[0046] The cameras 11 arranged according to Figure 1 with their optical axes 111 parallel to one another should be positioned close to one another along the scan line 23 (shown only in Figures 2, 4 and 6) so that adjacent cameras 11 form an overlap area 13 of at least half the angle of view 112 with each other, and furthermore there is only a slight overlap 14 with the angle of view 112, and the next nearest camera 11 if more than two cameras 11. In this case, gap-free coverage of the substrate surface 21 by the overlap area 13 should be guaranteed even in the case of height variations Δz of the substrate 2 and imprecise mechanical alignment.

[0047] Due to the fact that the optical axis 111 of the camera 11 is aligned perpendicular to the substrate 2, only half of the angle of view 112 is available at the edge of the substrate 2 or at the edge of the scan line 23 formed by the camera 11, and there is always an overlap area 13 also in the edge region of the substrate 2. This is because, in an entocentric camera 11, the localization of the target marks 22 present on the substrate 2 (the greater the distance of the target marks 22 from the optical axis 111) is determined by the focal plane F of the respective camera 11 in the camera imaging. n 5. Therefore, to determine the distance of a target mark 22 arbitrarily positioned on the surface 21 of the substrate 2, triangulation is performed from two camera images of adjacent cameras 11 along a scan line 23, and can be continued at every other point of the scan line 23, as long as there is an analyzable structure on the substrate 2 that is distant from the target mark 22.

[0048] In the z-direction, accurate determination of the height variation Δz of the substrate surface 21 is limited to areas with detectable points (analyzable structures), and the height profile of the substrate 2 must, in some cases, be supplemented by interpolated values.

[0049] Triangulation of the distance of the substrate surface 21 is important for determining the scanning position of the target mark 22, as any height variation Δz of the surface 21 of the substrate 2 can lead to substantial measurement errors when determining the x and y coordinates of the target mark 22, the closer this target mark 22 is to the edge of the angle of view 112 of the camera 11.

[0050] For selective illumination of the scan line 23 defined by the point of incidence of the optical axis 111 of the camera 11, light sources 17 are provided which are positioned a short distance from the substrate 2 within the housing 12 of the alignment unit 1 and arranged at various oblique angles of incidence.

[0051] As already mentioned above, half of the image capture area (field of view 112) may not be used by the outer camera 11 in the camera configuration according to Fig. 1. The above-mentioned drawbacks can be avoided and an alternative system configuration shown in Fig. 2, based on the Scheimpflug principle, allows optimal use of the scanning area inside the full field of view 112 of each of adjacent cameras 11 that are tilted relative to one another. However, this places increased demands on the objective lenses 15 as well as on the orientation and adjustment of the cameras 11.

[0052] While the first gapless alignment principle according to FIG. 1 uses five cameras 11 for a total detection width of >635 mm (>25″), the same detection width of the alignment unit 1 can be scanned with only four cameras 11 in the arrangement principle according to FIG. 2.

[0053] The detection width across all cameras 11 is dimensioned by the processing beam 45 (shown only in Figures 6 and 7) scanned by the polygon scanner to be larger than the maximum processing area of ​​the processing unit 4 (shown only in Figures 6 and 7), i.e., for example, larger than the maximum length of the processing path 41 on the substrate 2 to be produced.

[0054] The second condition regarding the number and arrangement of cameras 11 is the required object-side optical resolution, which is often fixed at about 10 μm / pixel depending on the size of the target mark to be detected and is realized at about 11 μm / pixel in the proposed example. The third boundary condition concerns the scanning speed, which should be adapted to the desired throughput of printed circuit boards at board speeds of 1000 mm / s to 1800 mm / s.

[0055] For the camera 11, a line camera with a sensor line 114 having an edge length of 11 μm×11 μm and more than 3000 pixels is mainly used as a compromise between a high readout speed, a maximization of the scanning width due to a long line length, and an acceptable price for the sensor line 114. The adjustment of the required width of the substrate 2 to the resolution of the line camera is performed by the imaging scale of the objective lens 15 of the camera 11.

[0056] In contrast to Figure 1, Figure 2 shows a configuration of four cameras 11 with optical axes 111 tilted relative to each other in a uniform camera plane along a scan line 23 to enable gap-free alignment of a target mark 22 for the same scan area (635 mm) as in Figure 1. Two cameras 11 are positioned according to the Scheimpflug condition to form a pair of cameras 11 that together have a larger overlap area 13 of their angles of view 112, corresponding to a complete overlap of the angles of view 112 of the two cameras 11.

[0057] If the substrate 2 is no wider than this scan line 23 from the field of view 112 of two adjacent cameras 11, triangulation for each substrate point along the scan line 23 can be calculated from two camera scans of only two adjacent cameras 11 that are tilted relative to each other. Alternatively, if the substrate width is wide, pairs of tilted cameras 11 can be aligned along the desired scan line 23 until the overlap region 13 of the two cameras 11 covers the entire width of the substrate 2. In this regard, the overlap regions 13 should at least intersect each other, but should also have a smaller overlap 14 due to possible height variations Δz of the substrate 2 and mechanical mounting and alignment tolerances of the cameras 11. This always ensures gapless scanning of the scan line 23 on the substrate 2 for maximum height variations Δz and mounting tolerances of the cameras 11, due to the additional overlap 14 of the overlap regions 13 of each pair of cameras 11 formed by the complete overlap of the field of view 112. The advantage of this camera configuration according to Figure 2 is that in the simplest case, exactly two cameras 11 "see" the same area of ​​the scan line 23 while complying with the Scheimpflug condition, and a sub-area of ​​the field of view 112 of the camera 11 remains unused. Thus, compared to Figure 1, one fewer camera 11 is used and the length of the scan line 23 remains the same, i.e., with the same substrate width.

[0058] At the same time, if there are a sufficient number of target marks 22 or other scannable structures in the overlap region 13, additional height triangulation is possible to determine the height deviation Δz of the substrate surface 21 for each pair of cameras 11 positioned according to the Scheimpflug condition.

[0059] Figure 3 shows one of the two cameras 11 tilted relative to each other, with different tilt angles of the objective lens 15 and sensor chip 113 (or the tilt of the objective lens relative to the camera, if the latter is considered separately from the objective lens 15) adjusted to correct the imaging of the object plane and image plane so as to satisfy the Scheimpflug condition.

[0060] In FIG. 4, a sensor line 114 is shown schematically as representing the camera 11 of the alignment unit 1 to illustrate a set of problems related to variations in the height of the substrate surface 21 using the example of substrate waviness. The top right portion of FIG. 4 shows a schematic representation of a table system 3 that moves in the y direction and on which the substrate 2 is placed. The alignment unit 1, which is reduced to the sensor line 114 and performs alignment of a target mark 22 (shown only in FIGS. 2 and 7 ) along a scan line 23, is located above the substrate 2. The substrate 2 to be scanned relative to the target mark 22 is assumed or known to be either unstable or in an undulating manner, resulting in height variations Δz of the substrate surface 21. During the forward relative movement of the sensor line 114 in the y direction, different heights are recorded along the scan line 23 (in the x direction). Depending on the position of the target mark 22 in the field of view 112 of the entocentric camera 11, these different heights result in an accurate determination of the x,y position of the target mark 22.

[0061] As a result of the forward feed of the table system 3, the sensor line 114 first scans the dotted scan line 23', resulting in the dashed profile line shown below. After several readout steps, the sensor line 114 detects the solid scan line 23 and records a solid profile line that is significantly different from the dashed profile line. These height variations Δz, which differ sharply in location, can lead to significant deviations of the exposed structure during processing by the processing unit 4 (only shown in FIG. 6 ), caused by defocusing of the processing beam 45. The defocus can only be eliminated by refocusing, when the position of the height variations Δz is accurately measured and the focus of the processing beam 45 is tracked along the processing line 41 adapted to the position of the target mark 22 and the height variations Δz.

[0062] FIG. 5 shows two adjacent cameras 11 with parallel optical axes 111 and two focal planes F of the sensor chip 113 lying in the same plane. n and F n+1 (n=0) and (n=0) in Fig. 1. An overlap region 13 of the field angles 112 (i.e., linear scanning areas) of the two cameras 11 is created. This is necessary because the target mark position detected in the xy plane on the substrate surface 21 during imaging by the entocentric objective lens 15 is sensitively dependent on the object position in the z direction. Therefore, by triangulation, which maps the height variation to two reference planes in the z direction, the registration target mark 22 is detected using the camera images of a pair of adjacent cameras 11, and the target position x, z is calculated. The lower plane is designated as the substrate surface 21, and the upper plane for identifying surface variations is designated as the substrate surface 21'.

[0063] Finally, the obtained x position and the obtained height z are determined from the positions of the different calibration values ​​z1, z0 detected at the two cameras 11 relative to the calibration planes of the substrate surfaces 21 and 21′ as follows:

number

[0064] This means that in addition to the accurate determination of the target mark position in x-position, the z-position can also be determined relative to the calibration plane z1, z0. In this way, (absolute) height measurements are possible.

[0065] Figure 6 shows a side view of the alignment unit 1 similar to the cross-sectional view on the right of Figure 1, and illustrates schematically the association of the determined position data of the target mark 22 (only shown in Figures 2 and 7) with the processing unit 4 via the computer unit 5. A set of problems related to the uneven substrate 2 is illustrated diagrammatically and enlarged for a corrugated substrate surface 21. The table system 3 is assumed to be a precision table.

[0066] As the table system 3 moves in the y direction, the recording unit 1 detects the x- and y-positions of target marks 22 arbitrarily arranged on the substrate 2 in linear scanning areas on the substrate 2 (scanning lines 23 formed by multiple line cameras perpendicular to the drawing plane) by successive line scans. The overlapping area 13 of the field of view 112 formed by the cameras 11 (visible only in FIGS. 1 and 2 ) ensures that, as a result of double scanning of each substrate point by two adjacent cameras 11, not only the exact target mark position can be determined by triangulation, but also the height variation Δz of the substrate surface 21 can be calculated. In addition to the usual alignment of the two-dimensional structure of the processing pattern with respect to the actual position of the target marks 22, the processing focus FP of the processing beam 45 along the processing path 41 (shown only in FIGS. 8 and 9 ) is then additionally adapted point-by-point by focus tracking 43 to the height variation Δz of the substrate surface 21 in the computer unit 5 from the measurement of the actual substrate height z at each point of the scan lines 23 detectable by the imaging structure.

[0067] In the exemplary embodiment of the invention shown in Figure 7, the substrate 2 is a continuous substrate that is tautly guided from roll to roll (not shown) via a rotary table system 31. The rotary table system 31 can have a drum diameter of 200 to 500 mm.

[0068] Due to the taught guidance of the continuous substrate 2 , the scanning line 23 (not visible in FIG. 7) of the camera 11 of the recording unit 1 can be positioned in front of the line of contact of the rotary table system 31 with the substrate 2 .

[0069] The recording unit 1 is formed with two entocentric cameras 11, the scanning areas of which form a scan line 23 (not visible) that extends beyond the edge of the substrate 2 and can also detect calibration marks 32 on the rotary table system 31. With regard to the need and handling of the calibration marks 32, reference is made to DE 102019128198.9, which has not been published until now.

[0070] Otherwise, the recording unit 1 detects all of the target marks 22 located on the substrate 2 being guided past by the rotary table system 31 in the same way as described for the flat substrate 2 with reference to Figures 1 and 2, regardless of the position on the substrate 2 at which the target marks 22 are located.

[0071] Due to the fact that the substrate 2, as a continuous substrate, is stretched taut on the rotary table system 31 and therefore does not have height variations Δz caused by waviness of the substrate 2, local point-by-point height measurements can be omitted in this embodiment of the present invention. Furthermore, height measurements of the substrate surface 21 may be limited to a small overlap region 13 of the field of view 112 of the two cameras 11. In this case, the overlap region 13 is much smaller than half the field of view 112 of the two cameras 11, but is at least 1 / 50 (>5 mm), preferably 1 / 40 to 1 / 10, of the detection area of ​​the recording unit 1 (i.e., the substrate width including the edge areas of the rotary table system 31). A particularly preferred overlap region is 1 / 35 to 1 / 25 (approximately 10 to 15 mm). Triangulation calculations are performed similarly to the description with reference to FIG. 5, from which the thickness of the substrate 2 and, in some cases, thickness variations over the entire length of the continuous substrate can be determined in this example. However, rapid focus changes along the processing path 41 by focus tracking 43, as described with reference to FIG. 6, are generally not required. However, thickness information, i.e., the z measurement, which is the height of the substrate surface 21, is absolutely necessary to calculate the x and y positions of the target marks 22. However, after a single initial determination (and possibly occasional repeated individual measurements), this can be retained for calculation of the positions of all target marks 22 across the entire successive substrate.

[0072] The processing units 4 aligned with the substrate surface 21 in different radial planes of the rotary table system 31 emit scanning processing beams 45 for introducing two-dimensional structures onto the processing path 41 of the substrate surface 21. However, they can also be arranged in a common plane diametrically opposite the recording unit 1 in the rotary table system 31 (e.g. in the axial plane of the rotary table system 31) (not shown).

[0073] According to the present invention, as explained with reference to Figures 4 and 6, high speed point-by-point focus tracking 43 of the processing beam 45 along a straight processing path 41 is required for height variations Δz caused by unevenness of the substrate 1 or substrate surface 21, so that this straight processing path 41 degenerates into processing lines of various heights.

[0074] Conventional autofocus systems are not suitable for these rapid focus changes in the z direction of the processing beam 45, which is scanned in the x direction and is a laser beam in a photolithography direct exposure process. The basis for the present invention's rapid implementation of local focus changes via the processing path 41 is the detection of height variations Δz of the substrate 2 simultaneously with the alignment of the target mark 22 by redundant double image capture by a concentric camera 11 with a gapless overlapping area 13 of a field of view 112 along a linear scanning area (scan line 23). This height measurement, performed for each image point of the scan line 23 by triangulation calculation and preceding the processing unit 4 in time and space, results in the processing unit 4. The point-by-point changes of the processing focus FP of the processing beam 45 along the processing path 41 can be calculated by the computer unit 5 according to the height variations Δz detected along the scan line 23 of the alignment unit 1 and calculated in the computer unit 5. This is in addition to the usual adaptation of the data of the two-dimensional structure pattern analyzed in the processing path 41 to the position of the substrate 2 acquired by the detected target mark 22.

[0075] Additional means to supplement the conventional focusing optics 44 are required for fast focus changes along the processing path 41. These means must be of such quality that they are at least twice the scanning frequency of the processing beam 45 in the transverse direction x relative to the movement direction y of the substrate 2. The focus change frequency is preferably 2 to 3 times, particularly preferably 5 to 20 times, the scanning frequency of the processing beam 45, which is in the range of 0.5 to 1 kHz when using a polygon scanner.

[0076] FIG. 8 shows a first possibility for realizing focus tracking 43 by means of a movable lens 431 .

[0077] 9 provides a fixed angle mirror 432 and a movable retroreflector 433. The angle mirror 432, placed on an already focused bundle, couples the focused bundle to the retroreflector 433, and then combines it again after reflection, and the retroreflector 433 moves towards or away from the angle mirror 432 in order to displace the focal point FP in the z direction.

[0078] A further mirror-based implementation of focus tracking 43 will now be described with reference to Figures 10 to 12. Figures 10 and 11 show a mirror assembly having a mirror with variable curvature, hereafter designated as an elastically bendable mirror 434. Figure 11 shows as a mechanical equivalent the operating principle in which the bendable mirror 434 is movably articulated in its edge regions to a mirror holder 436 of a base body and is in contact with a linear actuator in its central region in the form of a piezoelectric stack 435 supported in the same base body as the mirror holder 436.

[0079] 10 shows the physical implementation of the mirror assembly as a substantially monolithic component, with the mirror holder 436 as a rectangular parallelepiped carrying the elastically bendable mirror 434 as a monolithic tapered convex metal plate elastically mounted on two parallel linear flexure bearings. The bendable mirror 434 is therefore a convex or concave cylindrical mirror that can have curvature in only one spatial direction.

[0080] According to the configuration of FIG. 12, two elastically bendable mirrors 434, e.g., oriented laterally in the x and y directions, are arranged in the folded beam path of a multi-element focusing optics 44 for the processing beam 45 (shown only in FIGS. 7 and 8). In this case, a high-speed focus tracking 43 is incorporated into the conventional focusing optics 44. An intermediate focal plane 441 is provided for processing, locally adapted to the position of the target mark 22, and predetermines the point-by-point generation of a two-dimensional structure (not shown) that is transmitted in an image plane 442 to a polygon scanner (not shown), which is advantageously used to guide the processing beam 45 along a height-controlled processing line 41 on the substrate 2. The advantage of this embodiment of the high-speed focus control with two one-dimensionally operating focus tracking 43 is that different focusing can be used in the x direction (scanning direction of the processing beam 45) and the y direction (direction of substrate movement). Therefore, different focus changes can be manipulated (if necessary) using astigmatic or other aspherical optics in the scanning and cross-scanning directions of the processing beam 45.

[0081] By using the entocentric camera 11 for target mark alignment, the present invention makes it possible to realize a gap-free, nearly one-dimensional scan line 23 on a substrate 2 having height variations or curvature, which not only enables detection of the target mark 22 but also enables measurement of the height and height variation Δz of the substrate 2. Based on double scanning by the cameras 11 at two different positions along the scan line 23 of the alignment unit 1, triangulation measurements and triangulation calculations can be performed in the overlap region 13 by the entocentric line cameras with overlapping viewing angles 112. By point-by-point measurement, the height variation Δz of the substrate surface 21 can be taken into account by high-speed focus control in the processing unit 4, which also operates on a linear processing path 41. This is then corrected by focus tracking 43 or during control of the processing beam 45 point-by-point along the processing path 41 to form a height-adjusted processing line.

[0082] In addition, dynamic focus adjustment along the processing path 41 also simultaneously allows for correction of known imaging-dependent focus deviations (due to optical design or optical processing) of the processing beam 45 scanned along the processing path 41. [Explanation of symbols]

[0083] 1 Recording Unit 11 Camera 111 Optical axis 112 angle of view 113 Sensor Chip 114 Sensor Line 12 (recording unit) housing 13. Overlap area (of viewing angle) 14 Slight overlap (of the angle of view) 15 (camera 11) objective lens 151 Objective adapter 16 Image plane (of recording unit 1) 161 Camera Adapter 162 (of the sensor chip 113) surface normal 17 Light source (for illuminating the linear scanning area) 2 boards 21, 21' Substrate surface 22 Target Mark 23, 23' scanning lines 3 Table System 31 Roller Cable System (for continuous substrates) 32 Calibration Mark 4 Processing Unit 41 Processing Pathway 43 Focus Tracking 431 Movable Lens 432 (steady) angle mirror 433 (movable) retroreflector 434 (Elastic) Bendable Mirror 435 Piezoelectric Stack (Linear Actuator) 436 mirror holder 437 Flexure Bearing 44 Focusing optical system 441 intermediate images 442 Image plane 5 Computer Unit F n , F n+1 focal plane FP (Tracking) Focus x (along the width of substrate 2) y direction of movement (along the length of substrate 2) z focusing direction (along the height of substrate 2) Δz (of the substrate surface 21) height variation

Claims

1. 1. An apparatus for exposure control in photolithographic direct exposure of two-dimensional structures in a photosensitive coating on a substrate, comprising: an alignment unit for aligning a target mark disposed on a surface of the substrate; a movable table system for supporting and defining one-dimensional movement of the substrate below the alignment unit; a processing unit having a controllable linear processing path for photolithographic processing of a substrate with a processing beam to introduce a two-dimensional structure; a computer unit for controlling the alignment between the processing path and the substrate by local adjustment of the photolithography process in response to the position of the substrate determined by the aligned target marks; Equipped with The apparatus includes a recording unit (1) having a plurality of entcentric cameras (11) arranged in a linear array transverse to the one-dimensional motion of the substrate (2), forming a gap-free linear scanning region (23) across a predetermined width of the substrate (2), and having a field of view (112) extending in the direction of the linear scanning region (23), the field of view (112) of adjacent entcentric cameras (11) having an overlap region (13) along the linear scanning region (23) for detecting redundant image capture of the substrate (2) by adjacent cameras (11) within the overlap region (13), and the computer unit (5) having means for calculating the position of the target mark (22) from the redundant imaging in the overlap region (13) of the adjacent entcentric cameras (11) additionally using the height position of the target mark (22) determined by triangulation of the distance on the substrate surface (21).

2. 2. The apparatus of claim 1, wherein the alignment unit (1) is equipped with a plurality of entocentric cameras (11) for generating linearly continuous, gap-free sensor areas, with the field of view (112) of adjacent cameras (11) having an overlapping area (13) that is at least half the size of the field of view (112), and the computer unit (5) is adapted to determine a target mark (22) located anywhere across the width of the substrate (2) by triangulation of distances at any position on the substrate surface (21).

3. The apparatus according to claim 1 or 2, wherein the camera (11) is a line camera (11) for forming a narrow, tightly spaced linear scanning area (23), and has an overlap area (13) across the entire width of the substrate (2) via a camera (11) with a long scanning length.

4. 4. The apparatus according to claim 1, wherein the cameras (11) have optical axes (111) parallel to one another and are directed towards the substrate surface (21), and the overlapping areas (13) of the angles of view (112) of all the cameras (11) are of equal size.

5. The apparatus according to any one of claims 1 to 3, wherein two adjacent cameras (11) are directed toward the substrate surface (21) with optical axes (111) inclined relative to each other, and an overlapping region (13) of the angles of view (112) of the cameras (11) inclined relative to each other is adjusted so that the angles of view (112) of the two cameras (11) completely overlap on the substrate surface (21).

6. 6. The apparatus according to claim 5, wherein the overlapping area (13) formed by the cameras (11) in a pair tilted relative to one another is adjacent to at least one further overlapping area (13) without a gap so that the overlapping area (13) extends over at least the entire width of the substrate (2), and an overlap (14) can be provided between the pair of cameras (11) inclined relative to one another to ensure a gap-free scanning area (23) of the recording unit (1) for all allowable height variations (Δz) of the substrate surface (21).

7. 7. Apparatus according to claim 5 or 6, wherein the cameras (11) in pairs inclined relative to each other are arranged so as to be subjected to a Scheimpflug condition.

8. 8. The apparatus of claim 1, wherein the computer unit (5) further performs control for fast focus tracking (43) of the processing unit (4) along the processing path (41) in response to height variations (Δz) of the substrate surface (21), said control including triangulation of the target mark (22) or any imaged structures of the substrate surface (21) based on redundant image capture in overlapping regions (13) of adjacent entocentric cameras (11).

9. 2. The apparatus according to claim 1, wherein the alignment unit (1) has only two entocentric cameras (11) arranged on a scanning line (23) transverse to the direction of movement of the substrate (2) for detecting the target marks (22) with an overlapping area (13) of 1 / 100 to 1 / 3 of the angle of view (112) of the cameras (11), the substrate (2) being a flexible continuous substrate guided tautly without height fluctuations (Δz) on a rotary table system (31), the overlapping area (13) of the angle of view (112) of the two cameras (11) being configured so that triangulation can be applied for the purpose of accurate determination of the thickness of the substrate (2) in the overlapping area (13) of the angle of view (112) on the rotary table system (31) and can be assumed to be constant over its entire width.

10. 10. The apparatus according to claim 1, wherein the alignment unit (1) comprises light sources (17) for illuminating a linear gapless scanning area arranged so as to be uniformly distributed within the housing (12) to achieve a scanning line (23) that is homogeneously illuminated by dark field illumination or bright field illumination.

11. 11. The apparatus of claim 10, wherein the light source (17) is configured for continuous illumination and has an arrangement for controlling at least one characteristic including brightness, angle of incidence or spectral range.

12. 11. The device according to claim 10, wherein the light source (17) is adapted for continuous illumination, allowing image capture by controlling the integration time of the sensor lines (114) by means of an electronic shutter principle.

13. 13. The apparatus according to claim 1, wherein focus tracking (43) for height variations (Δz) of the substrate (2) is integrated into the processing unit (4), by means of which the height variations (Δz) determined by the computer unit (5) by triangulation from images redundantly captured by two adjacent cameras (11) of the alignment unit (1) can be adjusted in real time by fast focus correction of each image point of the recording unit (1), and the focus tracking (43) can be controlled based on changes in lens position, mirror position or mirror curvature.

14. 14. Apparatus according to claim 13, wherein the focus tracking (43) is controllable based on a change in the mirror curvature in at least a direction x transverse to the direction y of movement of the substrate (2).

15. 15. Apparatus according to claim 14, wherein the focus tracking (43) is separately controllable based on changes in the mirror curvature in the direction y of movement of the substrate (2) and in the lateral direction x.

16. Apparatus according to any of claims 13 to 15, wherein the focus tracking (43) is controllable by changing the mirror curvature by means of a piezoelectric element (435).

17. The apparatus of claims 13 to 16, wherein the focus tracking (43) is also applicable to correct image-dependent focus deviations of the upstream focus optics (44) or other upstream optical elements resulting from optical design or optical manufacturing, based on changes in lens position or mirror position or mirror curvature.

18. 1. A method for exposure control in photolithographic direct exposure of two-dimensional structures in a photosensitive coating on a substrate, comprising: In an alignment unit (1) for detecting a target mark (22) located on a substrate (2), a step of arranging a plurality of entcentric cameras (11) to form a gapless linear scanning area (23) transverse to a moving direction of the substrate (2), the entcentric cameras (11) having a field of view (112) extending along the linear scanning area (23) together with an overlapping area (13) formed by adjacent entcentric cameras (11) to obtain redundant image captures of the substrate (2) within the overlapping area (13) from the adjacent cameras (11); moving the substrate (2) on a movable table system (3) in a defined one-dimensional movement below the recording unit (1); providing a processing unit (4) for photolithographic fabrication of two-dimensional structures having a processing beam (45) controllable along a linear processing path (41); detecting the spatial positions of the target marks (22) in terms of length, width and height, randomly distributed over a given width of the substrate (2) during a single pass of the substrate (2) through a linear scanning area (23) of the recording unit (1); determining positions of target marks (22) randomly distributed across the width of the substrate (2) from redundant imaging in the overlapping region (13) of adjacent entocentric cameras (11) additionally using height positions of the target marks (22) determined from the redundant imaging of the adjacent entocentric cameras (11) by triangulation of the distance of the substrate surface; a processing unit (4) calculating data for alignment and local adjustment of processing of a substrate (2) having a two-dimensional structure, for controlling a processing beam (45) along a linear processing path (41) oriented transverse to the direction of movement of the substrate (2); controlling the alignment between the processing path (41) and the substrate (2) and local adjustments of the photolithography process in response to the position of the substrate (2) determined by the aligned target mark (22); A method for providing the above.

19. 19. The method according to claim 18, wherein the calculation of the spatial positions of the target marks (22) randomly distributed over the width of the substrate (2) is extended to triangulation of further detectable structures of the substrate (2) in redundant images captured in the overlap region (13) during the passage of the substrate (2) based on their height positions, and wherein fast focus adjustment of the focal point (FP) of the processing beam (45) is performed by focus tracking (43) along the processing path (41) based on control of a lens position or a mirror position or a mirror curvature.

20. 20. The method according to claim 19, wherein the fast focusing of the focal point (FP) of the processing beam (45) is performed at a frequency at least 2-3 times higher than the scanning frequency of the processing beam (45).

Images