Pattern Generation Method and Apparatus

Abstract

A method for rasterizing a pattern having a periodic component for an SLM is presented, comprising obtaining an original pattern having periodicity (S10). A first pattern main period is determined (S21). An image area and a first pitch of imaged elements are obtained (S31). The original pattern is scaled by a first raster scaling factor (S41). The scaled pattern is cropped to include a first integer number of repetitions of pattern items that exhibit periodicity in a first direction covered by the image area (S51), providing a rasterized pattern compatible with an intended pattern generator. The rasterized pattern is associated with data representing the first scaling factor. The method includes obtaining the rasterized pattern. Elements of the SLM of the pattern generator that are outside the rasterized pattern are set to disabled. The rasterized pattern is then optically scaled and imaged onto a target surface.

Description

Technical Field

[0001] The present invention generally relates to rasterization and drawing of patterns by a spatial light modulator pattern generator, and more particularly to a method and apparatus for rasterization and drawing of patterns having periodic components.

Background Art

[0002] Pattern generators are currently used in a variety of applications. Pattern generators used in lithography systems and photomask lithography systems are required to exhibit very accurate printing characteristics. One approach to obtaining high-quality pattern printing is to use a spatial light modulator (SLM), such as a digital micromirror device (DMD), a liquid crystal display (LCD), a grating light valve (GLV), a planar light valve (PLV), a microshutter array (MSA), an analog spatial light modulator (ASLM), and / or liquid crystal on silicon (LCS). The SLM has an array of individually controllable elements arranged to generate an array of imaged elements within an image area on a target surface. The illumination of the individual imaged elements is controlled by each such element.

[0003] The SLM has an inherent periodicity, and in applications where the printed pattern also has periodicity, different types of interference effects may occur. Such effects may remain in the final product and result in, for example, different types of screens that can be recognized by human vision. Also, even very small changes, if regular, can be easily observed and are sometimes referred to as mottling. The SLM used in pattern generators often has a fixed physical size and field aperture, and in some cases the edges may be tapered. Therefore, it is difficult to cope with subtle changes and trends in the pattern shape. Therefore, it is difficult to mitigate the interference phenomenon that occurs for periodic patterns.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Accordingly, a general object of the present invention is to provide an SLM-based method and apparatus adaptable to avoid interference effects when printing repetitive patterns.

Means for Solving the Problems

[0005] The above object is achieved by a method and apparatus according to the independent claims. Preferred embodiments are defined in the dependent claims.

[0006] Generally speaking, in a first aspect, a rasterization method of a pattern having a periodic component is presented. This method is targeted at a pattern generator based on an SLM. The SLM has an array of individually controllable elements arranged to generate an array of elements imaged within an image area on a target surface. The irradiation of each imaged element is controlled by each such element. The rasterization method includes obtaining an original pattern having a pattern item exhibiting periodicity. A first pattern main period in a first direction of the original pattern is determined. Information regarding the image area of the pattern generator to be used and a first pitch of the imaged elements in the first direction is obtained. The original pattern is scaled in the first direction by a first raster scaling factor, giving a scaled pattern. The first raster scaling factor is equal to a value obtained by dividing the first integer multiple of the first pitch of the pattern generator in the first direction by the first pattern main period. The scaled pattern is cropped to include a first integer number of repetitions of the pattern item exhibiting periodicity in the first direction, and includes an overlap taper merging margin, if any, covered by the intended image area of the pattern generator in the first direction, giving a rasterized pattern adapted to the intended pattern generator. The rasterized pattern is associated with data representing the first scaling factor.

[0007] In a second aspect, a method of drawing a pattern having a periodic component for a pattern generator based on an SLM is presented. The SLM has an array of individually controllable elements arranged to generate an array of imaged elements within an image region on a target surface. The irradiation of the individual imaged elements is controlled by the respective elements. The drawing method includes obtaining a rasterized pattern having associated data representing a first raster scaling factor that defines a scaling in a first direction of the rasterized pattern. The elements of the SLM within the pattern generator located outside the pattern rasterized in the first direction are set to be inactive. The rasterized pattern is drawn on the image region on the target surface. The drawing includes scaling by a first optical scaling factor in the first direction. The first optical scaling factor is non-unity.

[0008] In a third aspect, a rasterization module for a pattern generator based on an SLM is presented. The SLM has an array of individually controllable elements arranged to generate an array of elements imaged within an image region on a target surface. The irradiation of the individual imaged elements is controlled by the respective elements. The rasterization module has a processor and a memory. The memory includes instructions executable by the processor, whereby the rasterization module is configured to obtain an original pattern having pattern items presenting periodicity. The rasterization module is further configured to determine a first pattern main period in a first direction of the original pattern. The rasterization module is further configured to obtain information regarding the image region and a first pitch D1 of the imaged elements in the first direction of the intended pattern generator used. The rasterization module is further configured to scale the original pattern in the first direction by a first raster scaling factor to give a scaled pattern. The first raster scaling factor is equal to a value obtained by dividing a first integer multiple of the first pitch of the pattern generator in the first direction by the first pattern main period. The rasterization module is further configured to crop the scaled pattern to include a first integer number of repetitions of the pattern items presenting periodicity in the first direction and, if there is an overlap tapering margin covered by the image region in the first direction of the intended pattern generator, to include it, giving a rasterized pattern adapted to the intended pattern generator. The rasterized pattern is associated with data representing the first raster scaling factor.

[0009] In a fourth aspect, the pattern generator has a control module and an imaging module. The imaging module is arranged to draw a pattern in the image area by means of the SLM. The SLM has an array of individually controllable elements arranged to generate an array of elements imaged within the image area on the target surface. The irradiation of the individual imaged elements is controlled by each element. The control module is configured to obtain a rasterized pattern having associated data representing a first raster scaling factor that defines the scaling in a first direction of the rasterized pattern. The control module is further configured to set the SLM in the pattern generator arranged outside the pattern rasterized in the first direction to be inactive. The imaging module comprises optical means for scaling a pattern rasterized in the first direction by a first optical scaling factor before being drawn in the image area, controlled by the control module. The first optical scaling factor is not 1.

[0010] One advantage of the proposed technique is that the performance of the SLM can be adapted to any periodic pattern. Other advantages will be understood upon reading the detailed description.

Brief Description of the Drawings

[0011] The present invention can be best understood by reference to the following description taken in conjunction with the accompanying drawings, with its further objects and advantages.

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DETAILED DESCRIPTION OF THE INVENTION

[0012] Throughout the drawings, like or corresponding elements are designated by the same reference numerals.

[0013] To enhance the understanding of the proposed technology, it would be useful to first start with an overview of the geometric considerations in a pattern generator based on SLM.

[0014] FIG. 1 schematically shows a pattern generator 1 based on an SLM 2. The SLM 2 is here shown as an array 3 of individually controllable elements 4 (in this embodiment, radiation reflecting elements). Light 5 incident on the array 3 is reflected as a set of exposure beams 6 towards a target surface 10. The target surface 10 is typically supported by a target support 12. The individual elements 4 of the SLM 2 are controllable to enable or suppress reflection. The elements 4 of the SLM 2 can also be set to be inactive, thereby reducing the active portion of the array 3.

[0015] The light exiting the active portion of the SLM 2 is directed towards the target surface 10, and an array 20 of imaged elements 22 is formed thereon. The imaged elements 22 as a whole form an imaged region 14. As a result, the irradiation of the individual imaged elements 22 is controlled by the respective elements 4 of the SLM 2. Typically, there is a nominal optical scaling of the imaged region 14 with respect to the SLM array 20. This nominal scaling is a uniform scaling determined by different design parameters such as different distances and a normal optical system. Arrangements for achieving such nominal scaling are well known to those skilled in the art and will not be further described.

[0016] As described in the background, SLM2 can be configured in many different ways. The details of the operation of SLM2 are not so important for the present invention as long as individual control of the elements 4 is provided and SLM2 causes an array 20 of imaging elements 22 in the imaging region 14 on the target surface 10.

[0017] After exposure of the imaging region 14 according to the individual settings of the elements 4 of SLM2, the imaging region 14 can be moved. This can typically be performed by mechanically moving SLM2 relative to the target support 12 or by moving the target support 12, SLM2, or both. The movement of the imaging region 14 may also be performed at least in part by optical means.

[0018] FIG. 2 is a diagram schematically showing a part of the target surface 10. The imaging region 14 at the current position of the SLM is depicted as an array 20 of imaged elements 22. The imaged elements 22 are provided to have a first pitch D1 in the first direction 101 and a second pitch D2 in the second direction 102. In this figure, for the sake of explanation, the number of imaged elements is small. At present, some of the elements of the SLM can direct radiation towards the imaging region 14 and are shown in black. The selection of elements in the SLM is performed according to print data representing the pattern 30 intended for printing. The intended pattern 30 is only shown by a dotted line for reference and does not physically exist in the imaging region 14. However, it can be easily understood that the imaged elements 22 corresponding to the items in the pattern 30 emit light, and the imaged elements 22 corresponding to the regions between the items in the pattern 30 do not emit light. The region of the intended pattern 30 located outside the current imaged region 14 is shown by hatching and will be processed by a previous or subsequent printing step.

[0019] Note that in certain applications, the irradiation can be in an inverse relationship to pattern 30, i.e., only the imaged elements 22 outside the intended pattern are irradiated. However, this would correspond to a "negative" pattern 30.

[0020] Returning to FIG. 2, when the imaging region 14 is irradiated, the imaging region 14 may be moved before the next exposure is performed. In the figure, an example of the next position is indicated by the dashed line 14". Thereafter, another portion of the pattern 30 can be exposed on the target surface 10. In this way, the entire surface of the target surface 10 can be covered.

[0021] Note here that the displacement of the imaged region 14 may also be performed with a small overlap. And each pattern intended to correspond to the imaging region 14 may include a tapering margin to avoid edge effects between different imaging regions. This will be described further below. Another option is to use multiple exposures, which leads to the fact that the imaging region 14 moves only a small part of the width of the imaging region 14 and each point on the target surface 10 can be exposed multiple times. Such embodiments will be described in more detail below. It is also possible to perform multiple exposures of the same imaging region 14, i.e., without movement between the exposures.

[0022] Figure 3 shows a part of another target surface 10. Also shown is the pattern 30 exposed on the target surface 10, but only for reference. This pattern 30 is a periodic pattern having items 32 that exhibit periodicity. The pattern 30 has a first pattern main period PM1 in a first direction 101 and a second pattern main period PM2 in a second direction 102. Here, it can be seen that the items 32 of the pattern 30 are arranged to be somewhat different with respect to the imaged elements 22 they cover. The reason is that the first pattern main period PM1 is not a multiple of the first pitch D1 of the imaged element 22, and the second pattern main period PM2 is not a multiple of the second pitch D2 of the imaged element 22. Therefore, the lower left corner of the item 32 has a different position with respect to the lower left corner of the imaged element 22. Thus, the items 32 are typically displaced by a small distance both horizontally and vertically between each repetition. Such small repetitive displacements can cause different interference effects that give rise to the problem of non-uniformity, as described in the background.

[0023] To mitigate such effects, the present idea is presented. The basic idea is to adopt a two-step approach. In the first step, the print data of the pattern to be printed is modified to a period that matches the period of the SLM. This is to recalculate the data that will be the basis for the next print. In the second step, the actual printing is performed according to the recalculated print data. However, to achieve the required absolute size and relative size, this rendering is performed by scaling using an optical scaling factor in each direction.

[0024] Figure 4 is a flowchart showing this relationship. The partial method M1 is a rasterization method of a pattern having a periodic component for a pattern generator based on SLM. The partial method M2 is a drawing method of a pattern having a periodic component for a pattern generator based on SLM. These methods can be executed in relation to each other and can also utilize the same processing device. However, these methods are connected only by transferring information related to the rasterized pattern of the partial method M1 for use in the partial method M2 and can also be executed separately from each other.

[0025] Next, the effects of the first-stage method will be described in association with a series of figures. These figures are the imaginary states of the pattern in the imaging region on the target surface corresponding to the operations performed on the print data of the pattern. However, in this first-stage method, actual drawing is not performed, and all operations are performed only on the display of the print data of the pattern.

[0026] In FIG. 3, it was confirmed that there is a deviation in the array of repeating items and imaged elements. In FIG. 5, the same pattern is scaled to the scaling pattern 31. In the first direction 101, the pattern is scaled by the first raster scaling factor F1. In this specific example, F1 is slightly less than 1 (unity), and the scaled pattern 31 is narrower than the original pattern. This scaling changes the first pattern main period PM1 to the first scaled pattern main period PM1' so as to match the first integer n1 times the first pitch D1 of the SLM in the first direction 101.

[0027] When the original first pattern main period PM1, the first pitch D1 of the SLM, and the appropriate first integer n1 are known, the first raster scaling factor F1 can be calculated as follows. F1 = PM1' / PM1 = n1*D1 / PM1

[0028] In the second direction 102, the pattern is scaled by the second raster scaling factor F2. In this particular example, F2 is slightly greater than 1, and the scaled pattern 31 is taller than the original pattern. This scaling changes the second pattern main period PM2 to a second scaled pattern main period PM2' such that it matches an integer multiple n2 of the second pitch D2 of the SLM in the second direction 102.

[0029] If the original second pattern main period PM2, the second pitch D2 of the SLM, and the appropriate second integer n2 are known, the second raster scaling factor F2 can be calculated as follows. F2 = PM2’ / PM2 = n2 * D2 / PM2

[0030] Now, the scaled pattern 31 exactly matches the raster of the SLM. Each part of the repeated item 32 appears to have the same relationship to the imaged element 22. For example, the lower left corner of the illustrated item 32 now coincides with a corner of the imaged element 22 imaged elsewhere within the imaged region 14.

[0031] The imaged region 14 contains a total of k1 imaged elements 22 in the first direction 101. Also, the imaged region 14 contains a total of k2 imaged elements 22 in the second direction 102. However, in most cases where the number k1 of imaged elements 22 in the first direction 101 is not a multiple of the first integer n1, items of the scaled pattern 31 may partially extend outside the imaged region 14. Similarly, in most cases where the number k2 of imaged elements 22 in the second direction 102 is not a multiple of the second integer n2, items of the scaled pattern 31 may also partially extend outside the imaged region 14.

[0032] To avoid such partially covered items, pattern cropping is performed. Figure 6 schematically shows this. The number k1 of imaged elements 22 in the first direction 101 is cropped by the first difference Δk1, leaving k1' imaged elements 22 in the first direction 101. The number k1' of imaged elements 22 in this first direction 101 is selected to be a multiple of the main period PM1' of the first scaling pattern. In other words, K1’=L1*PM1’, where L1 is an integer.

[0033] Similarly, the number k2 of imaged elements 22 in the second direction 102 is cropped by the second difference Δk2, leaving k2' imaged elements 22 in the second direction 102. The number k2' of imaged elements 22 in this second direction 102 is selected to be a multiple of the main period PM2' of the second scaling pattern. In other words, K2’=L2*PM2’, where L2 is an integer.

[0034] In this way, the rasterized pattern 33 is created. The rasterized pattern conforms to the intended pattern generator. The rasterized pattern is also associated with data representing the first and second scaling factors to enable restoration of the original size and shape.

[0035] Also, when the pattern generator takes an approach having an overlap tapering margin as described above, the margin needs to be included in the rasterized pattern. FIG. 7 is a diagram schematically showing a tapering margin in a pattern generator based on an SLM. The current imaging region 14 has a central region 15 illustrated as a black region having a regular rasterized pattern. In the tapering region 13, in one or two directions around the central region 15, and includes a rasterized pattern, but typically is composed of a reduced intensity. In one embodiment, the intensity decreases from the maximum intensity at the boundary of the central region 15 to zero intensity at the outer boundary. The width of the tapering region is T1 in the first direction 101 and T2 in the second direction 102 in the illustrated example. The next imaged region 14' is illustrated by a dotted line. The next imaged region 14' is moved by a distance 17 in the first direction with respect to the present imaged region 14. It can be seen that the tapering regions 13, 13' of the present imaged region and the next imaged regions 14, 14' overlap, which means that another exposure of these regions is performed by the next imaged region 14'. By performing this double exposure together, a pattern similar to what would have been generated by the imaged elements in the central region is generated in the imaged elements. The use of the tapering margin is considered to reduce the edge effect of the imaged regions 14, 14'.

[0036] The cropping according to the present invention, when used, must be adapted to the tapering region. Accordingly, one embodiment of the rasterization method includes an additional step of performing an overlap intensity tapering of the edges of the rasterized pattern.

[0037] In such a case, the cropping needs to be performed as follows. K1’ = L1*PM1’ + T1, and K2’ = L2*PM2’ + T2 Here, T1 and T2 are the widths (pitch distances) of the overlap taper margins in the first and second directions 101 and 102, respectively.

[0038] In the above-presented example, the processing of the periodic pattern is performed in both directions. However, in certain applications, for example, when the periodicity of the pattern exists only in one direction, the corresponding processing can, of course, be made to be performed only in one direction.

[0039] FIG. 8 is a flow diagram of steps of an embodiment of a method for rasterizing a pattern having a periodic component for a pattern generator based on an SLM. The SLM has an array of individually controllable elements arranged to generate an array of imaged elements within an image region on a target surface, and the irradiation of each imaged element is controlled by the respective element. In step S10, an original pattern is obtained. The original pattern has pattern items having periodicity. In step S21, a first pattern main period PM1 in a first direction of the original pattern is determined. In step S31, information regarding a first pitch D1 of the imaged elements in the first direction and the image region of the pattern generator to be used is obtained. In step S40, scaling of the original pattern is performed. In some steps S41, the original pattern is scaled in the first direction by a first raster scaling factor, giving a scaled pattern. The first raster scaling factor is equal to a value obtained by dividing the first integer multiple of the first pitch of the pattern generator in the first direction by the first pattern main period. In step S50, cropping is performed. In some steps S51, the scaled pattern includes a first integer number of repetitions of the pattern items exhibiting periodicity in the first direction, and if there is an overlap tapering margin covered by the image region in the first direction of the intended pattern generator, it is cropped to include it. Thereby, a rasterized pattern adapted in one direction to the intended pattern generator is obtained. The rasterized pattern is associated with data representing the first scaling factor.

[0040] The above procedure takes into account that the original pattern is repeated (at least) in one direction. If the pattern is repeated only in one direction, these procedures would be able to mitigate the effects of different non-uniformities.

[0041] In the above example, a two-dimensional SLM is assumed. However, this idea is also applicable to a one-dimensional SLM. By the above steps, the influence of non-uniformity in the direction of the SLM array is reduced, but the influence of non-uniformity in the orthogonal direction has to be dealt with by other means, which is outside the scope of this idea.

[0042] In addition, when the original pattern also has periodicity in the second direction and the SLM is a two-dimensional SLM, additional steps may be executed. In step S22, the second main period PM2 of the original pattern in the second direction is determined. The second direction is a direction orthogonal or at least intersecting to the first direction. In step S32, information regarding the image region of the intended pattern generator to be used and the second pitch D2 of the imaging elements in the second direction is acquired. In step S40 of scaling the original pattern, a further step S42 further includes scaling the original pattern in the second direction by a second raster scaling factor to give a scaled pattern. The second raster scaling factor is equal to the value obtained by dividing twice the second pitch of the pattern generator in the second direction by the second main period of the pattern. Step S50 of cropping further includes cropping the scaled pattern to also include twice the number of repetitions of the pattern item exhibiting periodicity in the second direction, and if there is an overlap tapering margin covered by the image region of the intended pattern generation in the second direction, including it, and having step S52 of giving a rasterized pattern. Thereby, the rasterized pattern is further associated with data representing the second raster scaling factor.

[0043] By this method, a rasterized pattern operating as print data, or a definition of the rasterized pattern, is obtained. The rasterized pattern has a raster scaling factor associated therewith.

[0044] When performing actual rendering, a rasterized pattern and its associated raster scaling factor are obtained. If the entity performing the rendering is the same as the one that performed the rasterization, all the data is already available, and the rasterized pattern can usually be obtained by simply retrieving it from memory. When another entity performs the rendering, the data representing the rasterized pattern and its associated raster scaling factor need to be transferred to the entity performing the rendering to obtain the pattern.

[0045] Figure 9 schematically shows a state where the obtained rasterized pattern 35 is superimposed on the array 3 of elements 4 of the SLM to be used. As described above, due to cropping, the rasterized pattern 35 may not utilize all the elements 4 of the SLM. In other words, some elements of the SLM will not be used during printing. Therefore, first, it is checked which parts of the elements of the SLM of the pattern generator are outside the rasterized pattern. And these elements indicated by 4’ are set to be invalid and are shown hatched as illustrated. That is, optical cropping similar to cropping in the rasterization stage is performed.

[0046] In the illustrated case, the disabled elements are shown on one edge of the SLM. However, it is also possible to disable elements in one or both directions on both sides of the remaining pattern.

[0047] The rasterized pattern may be somewhat distorted compared to the original pattern provided as input to the rasterization method. In most embodiments, it is an object to restore such distortion. For this object, the pattern generator has an imaging module arranged to draw a pattern in the image area. This imaging module has optical means configured to perform an optical scaling of the pattern when the pattern is drawn in the image area. This scaling can be controlled to be different in different directions.

[0048] By utilizing such optical scaling, the scaling factor associated with the rasterized pattern can be used to control the optical scaling during the drawing of the pattern. When restoring the original shape of an item within the pattern, the optical scaling factor used is selected to be equal to the reciprocal of the respective raster scaling factor.

[0049] The optical scaling is performed between the SLM and the target area, and is provided as an adjustment of the nominal optical scaling between the SLM and the target surface in the pattern generator described above, or as an overlay thereto. In this way, the SLM acts on the rasterized pattern adapted to the division into an array of elements of the SLM. At the same time, the radiation reaching the target area is restored by the means of optical scaling to reproduce the original shape.

[0050] FIG. 10 schematically shows this optical scaling. The radiation that has passed through the SLM is shown at the top of FIG. 10. The pattern retains the shape of the rasterized pattern as it is. The bottom of FIG. 10 shows the pattern drawn on the target region, i.e., the pattern after passing through the optical scaling of the imaging module. The imaged element 22’ is rescaled according to the optical scaling and covers a scaled imaging region 14’ that is different from the nominal one. However, the shape of item 32 is restored to the originally intended shape.

[0051] In the above-described embodiments, the operations that affect the drawn pattern are performed in both directions. However, similar to what was described with a partial method of rasterization, in certain applications where, for example, the periodicity of the pattern only exists in one direction, the corresponding operations, of course, can only be performed in one direction.

[0052] In some applications, there is no clear requirement to maintain an exact shape during the drawing process. In some such applications, there may even be a desire to obtain a certain remaining shape change of the drawn pattern. In such applications, the applied optical scaling may be different from the reciprocal of each raster scaling factor.

[0053] FIG. 11 is a flowchart of steps of an embodiment of a method of drawing a pattern having a periodic component for a pattern generator based on an SLM. The SLM has an array of individually controllable elements arranged to generate an array of imaged elements within an image region on a target surface, and the irradiation of each imaged element is controlled by the respective element. In step S60, a rasterized pattern is acquired. In sub-step S61, data representing a first raster scaling factor associated with the rasterized pattern is acquired. This first raster scaling factor defines the scaling in a first direction of the rasterized pattern. In step S70, the elements of the SLM are set to inactive. In sub-step S71, the elements of the SLM in the pattern generator located outside the rasterized pattern in the first direction are set to inactive. In step S80, the rasterized pattern is drawn on the image region on the target surface. In sub-step S81, the drawing includes scaling with a first optical scaling factor in the first direction. The first optical scaling factor is non-unity.

[0054] In a particular embodiment, the first optical scaling factor is equal to the reciprocal of the first raster scaling factor.

[0055] If the original pattern also has periodicity in the second direction, additional steps may be performed. The step S60 of obtaining the rasterized pattern may include a sub-step S62 in which the rasterized pattern is further associated with data representing a second raster scaling factor. The second raster scaling factor defines the scaling in the second direction of the rasterized pattern. The second direction is orthogonal or at least intersects the first direction. The step S70 of setting the elements of the SLM to be invalid further includes a step S72 of setting the elements of the SLM in the pattern generator located outside the rasterized pattern in the second direction to be invalid. The drawing step S80 further includes a step S82 of performing scaling by a second optical scaling factor in the second direction.

[0056] In a particular embodiment, neither the first optical scaling factor nor the second optical scaling factor is 1.

[0057] In a particular embodiment, the second optical scaling factor is equal to the reciprocal of the second raster scaling factor.

[0058] In the above example, both the repeating pattern and the array of SLM elements exhibit orthogonal principal axes of symmetry. It is also assumed that the array of imaged elements on the target surface is parallel to the intended direction of the periodic pattern. However, in other embodiments, other relationships and geometries may be utilized.

[0059] As a simple example, a cuboid-shaped SLM array, i.e., a case where the distance between two adjacent elements is different in two orthogonal directions. In this case, the two directions are processed separately, and different pitch values can be input, so it can be used very easily.

[0060] In one embodiment, the element array of the SLM can be arranged on non-orthogonal axes. An example is to use an SLM having hexagonal symmetry. In this case, the main symmetry axes of the element array are oriented at 60° to each other. At this time, the elements to be imaged also exhibit hexagonal symmetry. One of the axes of the array of imaged elements may coincide with, for example, the first direction of the array of periodic patterns. The pitch in this direction is the distance between two consecutive imaged elements in this direction. However, the pitch in the orthogonal direction will alternatively be the distance in the second direction between two lines in the first direction of the imaged elements, that is, the distance between the rows of imaged elements. In this embodiment, the pitch in the second direction will depend on the distance between two adjacent imaged elements and the angle of 60°. This is schematically shown in FIG. 12. The distances between adjacent imaged elements are d1 and d2 respectively in the main symmetry directions. The pitch D1 in the first direction is equal to d1, while the pitch D2 in the second direction will depend on the distance d2 corrected depending on the angle between the second main symmetry axis and the second direction.

[0061] Another example of a relative shape that can be used is to use an SLM array that generates an array of imaged elements that does not align with the symmetry axis of the periodic pattern. Such a situation is illustrated in FIG. 13. One current imaged region 14 is shown together with the next imaged region 14' (dotted line). The symmetry axes of the imaged elements are rotated by angles α1 and α2 clockwise with respect to the first and second directions respectively. In most cases, the angle α1 is equal to the angle α2.

[0062] In other words, in one embodiment, the first main axis of the array of imaged elements is rotated by a first angle with respect to the first direction, whereby the first pitch depends on the distance between two consecutive imaged elements along the first main axis and the first angle.

[0063] In a further embodiment, the second major axis of the array of imaged elements is rotated at a second angle with respect to the second direction, whereby the second pitch depends on the distance between two consecutive imaged elements along the second major axis and the second angle.

[0064] In some pattern generators, multiple exposures may be utilized. One way to arrange multiple exposures of the target surface is to move the image area of the SLM on the target surface by less than the full width of the image area between two exposures. A typical arrangement is to correspond the movement between two exposures to an integer fraction of the width of the image area. As an example, if the image area is moved by 1 / 4 of the image area width between each exposure, each spot on the target surface will be exposed four times. This is schematically shown in FIG. 14. The arrangement of imaged elements, i.e., the imaged area 14, is in this example the width of 16 imaged elements 22. Between each exposure, the imaged area 14 is moved by a distance corresponding to four imaged elements as shown by the dotted line indicating the next imaged area 14'. Twelve columns of imaged elements will expose spots on the already exposed target surface, and four columns of imaged elements will expose new portions of the target surface.

[0065] As will be understood by those skilled in the art, the multiple exposure method can be carried out by any integer fraction of the image area. However, the width of the imaged area should include a number such that this integer fraction covers an integer number of imaged elements to facilitate control of the overall drawing process. That is, it is preferable that the number of imaged elements in the moving direction is an integer multiple of the number of multiple exposures.

[0066] In a system designed according to the main concepts presented here, the number of imaged elements within the imaged area can depend on the raster scaling factor and the cropping of the SLM area in the subsequent moving direction of the imaged area. As a result, the number of imaged elements used in the moving direction may vary for each pattern. However, since the scaling factor can be freely selected in principle, within at least a certain range, the scaling factor can be selected to meet the preferred multiple exposure conditions.

[0067] For example, when performing 6 - fold superposition exposure, the entire imaged area generated by the SLM must contain a number of imaged elements divisible by 6 in the moving direction. Further, assume that the full width of the SLM contains 50 imaged elements. At this time, if the periodic pattern has a periodicity corresponding to 6.7 times the pitch of the imaged elements, when ignoring the limitations of multiple exposure, scaling up the periodic pattern to 7 times the pitch of the imaged elements and cropping the width of the imaged area to 7 repetitions of the pattern, that is, 49 imaged elements, would be a natural option for scaling. However, since 49 is not divisible by 6, multiple exposure is difficult. Instead, if the periodic pattern is scaled down to 6 times the pitch of the imaged elements, 48 imaged elements can be cropped in 8 repetitions, and in this case, multiple exposure can also be accommodated.

[0068] In other words, in one embodiment, the rasterization method further includes obtaining data regarding a first partial overlap exposure number having displacements equidistant in a first direction of a target pattern generator. The first raster scaling factor in the scaling step and the first integer repetition number in the cropping step are selected such that the value obtained by multiplying the first integer repetition number by the ratio between the first integer and the first partial overlap exposure number is an integer. Preferably, the first raster scaling factor is selected to be as close to 1 as possible, taking into account any constraints in the selection of the first integer and the first integer repetition number.

[0069] When multiple exposures are made more sophisticated, multiple exposures can be performed in both the first direction and the second direction. In that case, the same concept as above can be applied to the second direction as well.

[0070] In other words, in a further embodiment, the rasterization method further includes obtaining data regarding a second partial overlap exposure number having displacements equidistant in a second direction of a target pattern generator. Then, the second raster scaling factor in the scaling step and the second integer repetition number in the cropping step are selected such that the value obtained by multiplying the second integer repetition number by the ratio between the second integer and the second partial overlap exposure number is an integer. Preferably, the second raster scaling factor is selected to be as close to 1 as possible, taking into account any constraints in the selection of the second integer and the second integer repetition number.

[0071] This idea is applicable to any drawing method, but the original target technical field was its application to a lithography system or a photomask lithography system. Therefore, in a preferred embodiment, the pattern generator is a lithography system or a photomask lithography system.

[0072] In FIG. 15, an embodiment of a rasterization module 60 for a pattern generator based on an SLM is shown. As described above, the SLM has an array of individually controllable elements arranged to generate an array of elements imaged within an image area on a target surface, and the illumination of each imaged element is controlled by the respective element. The rasterization module has a processor 62 and a memory 64. The memory 64 contains instructions executable by the processor 62. Thereby, the rasterization module is configured to obtain an original pattern having pattern items exhibiting periodicity, determine a first pattern main period in a first direction of the original pattern, and obtain information regarding a first pitch of the imaged elements in the first direction of the image area and the pattern generator to be used. The instructions further enable the processor 62 to scale the original pattern in the first direction by a first raster scaling factor and provide the scaled pattern. The first raster scaling factor is equal to a value obtained by dividing an integer multiple of the first pitch of the pattern generator in the first direction by the first pattern main period. The instructions further enable the processor 62 to crop the scaled pattern to include a first integer number of repetitions of the pattern items exhibiting periodicity in the first direction and, if there is an overlap tapering margin covered by the intended image area of the pattern generator in the first direction, include it, and provide a rasterized pattern adapted to the intended pattern generator. The rasterized pattern is associated with data representing the first raster scaling factor.

[0073] In a preferred embodiment, the memory 64 further includes instructions executable by the processor 62, whereby the rasterization module is further configured to determine a second pattern main period in a second direction of the original pattern, the second direction being orthogonal to the first direction. The instructions further enable the processor 62 to obtain information regarding an image area in the second direction of the intended pattern generator and a second pitch of the imaged elements, scale the original pattern in the second direction by a second raster scaling factor, and provide a scaled pattern. The second raster scaling factor is equal to a value obtained by dividing a second integer multiple of the second pitch of the pattern generator in the second direction by the second pattern main period. The instructions further enable the processor 62 to include a second integer number of repetitions of pattern items exhibiting periodicity in the second direction and crop the scaled pattern to include, if any, an overlap tapering margin covered by the image area in the second direction of the intended pattern generator, and provide a rasterized pattern adapted to the intended pattern generator. The rasterized pattern is further associated with data representing the second raster scaling factor.

[0074] FIG. 16 shows an embodiment of a pattern generator system 70 including a rasterization module 60 and a pattern generator 80. In this embodiment, the rasterization module 60 provides data representing a rasterized pattern having associated data representing a scaling factor. In this embodiment, the rasterization module 60 is illustrated as a separate unit. Thereafter, the rasterized pattern can be transferred to the pattern generator 80 via a communication connection 62 or by wireless alternative means. Alternatively, the data representing the rasterized pattern can be provided by the rasterization module 60 in a data storage device physically brought to the pattern generator 80 for access.

[0075] However, in other embodiments, the rasterization module 60 may be provided as part of the pattern generator 80, as indicated by the dashed line. In this case, the processing power is preferably shared between the pattern generator 80 and the rasterization module 60. And the transfer of the rasterized pattern from the rasterization module 60 to the pattern generator 80 is performed by internal means.

[0076] FIG. 17 is a diagram schematically showing an embodiment of the pattern generator 80. The pattern generator 80 has a control module 82 and an imaging module 84. The imaging module 84 is arranged to draw a pattern in the image area. The imaging module includes an SLM2. The SLM2 has an array 3 of individually controllable elements 4 arranged to generate an array of elements imaged within the image area on the target surface 10. The irradiation of the individual imaged elements is controlled by the respective elements 4 based on instructions from the control module 84.

[0077] The control module 82 is configured to obtain a rasterized pattern having associated data representing a first raster scaling factor that defines the scaling in the first direction of the rasterized pattern. As described above, this rasterized pattern can be provided in different ways from internal or external sources.

[0078] The control module 82 is further configured to disable the elements 4 of the SLM2 in the arrangement of the pattern generator located outside the pattern rasterized in the first direction.

[0079] The imaging module 84 is controlled by the control module 82 and includes optical means 88 for scaling the rasterized pattern in the first direction by a first optical scaling factor before being drawn in the image area. The first optical scaling factor is not 1.

[0080] In one embodiment, the first optical scaling factor is equal to the reciprocal of the first raster scaling factor.

[0081] In one embodiment, the control module 84 is further configured to obtain a rasterized pattern that further has associated data representing a second raster scaling factor that defines the scaling in the second direction of the rasterized pattern. The second direction is orthogonal to the first direction.

[0082] The control module 82 is further configured to also disable the element 4 of the SLM2 in the pattern generator arrangement 80 located outside the pattern rasterized in the second direction.

[0083] The imaging module includes optical means 88 controlled by the control module 82 to further scale the rasterized pattern by a second optical scaling factor in the second direction before being drawn in the image area.

[0084] In one embodiment, neither the first optical scaling factor nor the second optical scaling factor is 1.

[0085] In one embodiment, the second optical scaling factor is equal to the reciprocal of the second raster scaling factor.

[0086] FIG. 18 shows one embodiment of the optical means 88 for scaling an exposure beam representing a rasterized pattern. The rasterized pattern is scaled by a first optical scaling factor in the first direction and optionally by a second optical scaling factor in the second direction before being drawn in the image area.

[0087] At the top of the figure, a schematic diagram in the second direction is shown. Six lens elements 91 to 96 are provided, among which the lens elements 91, 93, and 95 perform optical scaling in the first direction. The lens elements 91, 93, and 95 are cylindrical lenses having a center of curvature along an axis perpendicular to the figure shown. The lens elements 91 and 93 are movable along the optical axis to provide different optical scalings. The lens element 95 is fixed.

[0088] At the top of the figure, a schematic diagram in the second direction is shown. Six lens elements 91 to 96 are provided, among which the lens elements 91, 93, and 95 perform optical scaling in the first direction. The lens elements 91, 93, and 95 are cylindrical lenses having a center of curvature along an axis perpendicular to the figure shown. The lens elements 91 and 93 are movable along the optical axis to provide different optical scalings. The lens element 95 is fixed.

[0089] The above embodiment of the optical means 88 is only an example of a method for obtaining optically adjustable scaling different in different directions. Those skilled in the art will recognize that similar arrangements with different numbers and types of lenses can be used, and other optical arrangements can be used to adapt the scaling to be different in different directions.

[0090] In different embodiments, SLM2 can include a digital micromirror device, a liquid crystal display, a grating light valve, a planar light valve, a microshutter array, an analog spatial light modulator, and / or liquid crystal on silicon.

[0091] In one embodiment, the pattern generator is a lithography system or a photomask lithography system.

[0092] In one embodiment, the pattern generator 80 has a plurality of SLM2s. Thereby, the control module 84 is configured to individually control each SLM2 according to the obtained rasterized pattern.

[0093] The above-described embodiments are to be understood as a few exemplary examples of the present invention. It will be understood by those skilled in the art that various modifications, combinations, and changes can be made to the embodiments without departing from the scope of the present invention. In particular, different component solutions in different embodiments can be combined in other configurations if technically possible. However, the scope of the present invention is defined by the appended claims. [Example 1] A rasterization method for a pattern having a periodic component for a pattern generator based on a spatial light modulator (2), wherein the spatial light modulator (2) has an array (3) of individually controllable elements (4) arranged to generate an array (20) of elements (22) imaged within an image region (14) on a target surface (10), and the irradiation of the individual imaged elements (22) is controlled by the respective said elements (4), and the rasterization method comprises a step (S10) of obtaining an original pattern (30) having a pattern item (32) exhibiting periodicity; a step (S21) of determining a first pattern main period (PM1) in a first direction (101) of the original pattern (30); a step (S31) of obtaining information regarding a first pitch (D1) of the imaged elements (22) in the first direction (101) of the image region (14) and the intended pattern generator used; a step of scaling the original pattern (30) in the first direction (101) by a first raster scaling factor (S41) to give a scaled pattern (31), wherein the first raster scaling factor is equal to a value obtained by dividing a first integer multiple of the first pitch (D1) of the pattern generator in the first direction (101) by the first pattern main period (PM1); a step of cropping the scaled pattern (31) (S51) to include a first integer number of repetitions of the pattern item (32) exhibiting periodicity in the first direction (101) and, if there is an overlap tapering margin covered by the image region (14) of the intended pattern generator in the first direction (101), including it, to give a rasterized pattern (33) adapted to the intended pattern generator, wherein the rasterized pattern (33) is associated with data representing the first scaling factor; A rasterization method comprising. [Example 2] The first principal axis of the array (20) of the imaged elements (22) is rotated at a first angle (α1) with respect to the first direction (101), whereby the first pitch (D1) depends on the distance (d1) between two consecutive ones of the imaged elements (22) along the first principal axis and the first angle (α1). The rasterization method according to Example 1, characterized in that. [Example 3] Step (S22) of determining a second pattern main period (PM2) in a second direction (102) of the original pattern (30), wherein the second direction (102) is orthogonal to the first direction (101), step; Obtaining (S32) information regarding a second pitch (D2) of the imaged elements (22) in the second direction (102) of the image area (14) and the intended pattern generator used; and further including, Thereby, the step of scaling the original pattern further includes scaling (S42) the original pattern (30) in the second direction (102) with a second raster scaling factor, giving the scaled pattern (31), The second raster scaling factor is equal to a value obtained by multiplying a value obtained by dividing the second pitch (D2) of the pattern generator in the second direction (102) by the second pattern main period (PM2) by a second integer, Thereby, the cropping step further includes cropping (S42) the scaled pattern (31) to include a second integer number of repetitions of the pattern item (32) exhibiting periodicity in the second direction (102) and, if there is an overlap tapering margin covered by the image area (14) in the second direction (102) of the intended pattern generator, also including that, giving the rasterized pattern (33), Thereby, the rasterized pattern (33) is further associated with data representing the second raster scaling factor, The rasterization method according to Example 1 or 2, characterized in that. [Example 4] The second principal axis of the array (20) of the imaged elements (22) is rotated at a second angle (α2) with respect to the second direction (102), whereby the second pitch (D2) depends on the distance (d2) between two consecutive ones of the imaged elements (22) along the second principal axis and the second angle (α2), the rasterization method according to Example 3. [Example 5] The method further comprises the step of obtaining data on the number of first partial overlapping exposures having equidistant displacements in the first direction (101) of the intended pattern generator, whereby the first raster scaling factor in the scaling step (S41) and the first integer repetition number in the cropping step (S51) are selected such that the value obtained by multiplying the first integer repetition number by the ratio of the first integer and the number of first partial overlapping exposures is an integer, the rasterization method according to any one of Examples 1 to 4. [Example 6] The method further comprises the step of obtaining data on the number of second partial overlapping exposures having equidistant displacements in the second direction (102) of the intended pattern generator, whereby the second raster scaling factor in the scaling step (S42) and the second integer repetition number in the cropping step (S52) are selected such that the value obtained by multiplying the second integer repetition number by the ratio of the second integer and the number of second partial overlapping exposures is an integer, the rasterization method according to Example 3 or 4, or, if dependent on Example 3 or 4, the rasterization method according to Example 5. [Example 7] The first raster scaling factor is selected to be as close to 1 as possible, taking into account any constraints in the selection of the first integer and the first integer repetition number, and the second raster scaling factor is selected to be as close to 1 as possible, taking into account any constraints in the selection of the second integer and the second integer repetition number, characterized by comprising at least one of the above, the rasterization method according to any one of Examples 1 to 6. [Example 8] A method of drawing a pattern having a periodic component for a pattern generator based on a spatial light modulator (2), wherein the spatial light modulator (2) is an individually controllable element (4) arranged to generate an array (20) of elements (22) imaged within an image region (14) on a target surface (10). The irradiation of each imaged element (22) is controlled by the respective element (4), and the drawing method includes: Obtaining (S61) a rasterized pattern having associated data representing a first raster scaling factor that defines scaling in a first direction (101) of the rasterized pattern (33); Disabling (S62) the elements (4) of the spatial light modulator (2) in the pattern generator that are located outside the rasterized pattern in the first direction (101); Drawing (S80) the rasterized pattern on an image region (14) on the target surface (10), including: The drawing (S80) includes scaling (S81) in the first direction (101) with a first optical scaling factor; The first optical scaling factor is not 1; Drawing method. [Example 9] The drawing method according to Example 8, characterized in that the first optical scaling factor is equal to the reciprocal of the first raster scaling factor. [Example 10] The rasterized pattern is further associated with data representing a second raster scaling factor that defines scaling in a second direction (102) of the rasterized pattern (33), and the second direction (102) is orthogonal to the first direction (101). The step of disabling the elements (4) of the spatial light modulator (2) further includes disabling (S72) the elements (4) of the spatial light modulator (2) in the pattern generator that are located outside the rasterized pattern in the second direction (102). Thereby, the drawing (S80) further includes scaling (S82) in the second direction (102) with a second optical scaling factor. The drawing method according to Example 8 or 9, characterized by the above. [Example 11] Neither the first optical scaling factor nor the second optical scaling factor is 1, and both reach the image area. The drawing method according to Example 10, characterized by this. [Example 12] The drawing method according to Example 10 or 11, characterized in that the second optical scaling factor is equal to the reciprocal of the second raster scaling factor. [Example 13] A rasterizing module (60) for a pattern generator based on a spatial light modulator (2), wherein the spatial light modulator (2) is an individually controllable element (4) arranged to generate an array (20) of elements (22) imaged within an image area (14) on a target surface (10). The irradiation of each imaged element (22) is controlled by the respective element (4), and the rasterizing module (60) has a processor (62) and a memory (64). The memory (64) contains instructions executable by the processor (62), whereby the rasterizing module (60) obtains an original pattern (30) having a pattern item (32) exhibiting periodicity, determines a first pattern main period (PM1) in a first direction (101) of the original pattern (30), obtains information regarding the first pitch (D1) of the imaged elements (22) in the first direction (101) of the image area (14) and the intended pattern generator to be used, scales the original pattern (30) in the first direction (101) by a first raster scaling factor to give a scaled pattern (31), The first raster scaling factor is equal to a value obtained by dividing an integer multiple of the first pitch (D1) of the pattern generator in the first direction (101) by the first pattern main period (PM1), The scaled pattern (31) is cropped to include an integer number of repetitions of the first pattern item (32) exhibiting periodicity in the first direction (101), and if there is an overlap tapering margin covered by the image area (14) in the first direction (101) of the intended pattern generator, it is included, to give a rasterized pattern (33) adapted to the intended pattern generator. The rasterized pattern (33) is associated with data representing the first raster scaling factor. A rasterization module (60), characterized in that it is configured as such. [Example 14] The memory (64) further includes instructions executable by the processor (62), whereby the rasterization module (60) further determines a second pattern main period (PM2) in a second direction (102) of the original pattern (30), the second direction (102) being orthogonal to the first direction (101), obtains information regarding the imaged element (22) in the second direction (102) of the image area (14) and the intended pattern generator used, scales the original pattern (30) in the second direction (102) by a second raster scaling factor to give the scaled pattern (31), the second raster scaling factor being equal to a value obtained by dividing twice an integer multiple of the second pitch (D2) of the pattern generator in the second direction (102) by the second pattern main period (PM2), clips the scaled pattern (31) to include a second integer number of repetitions of the pattern item (32) exhibiting periodicity in the second direction (102) and, if there is an overlap taper margin covered by the image area (14) of the intended pattern generator in the second direction (102), includes it, to give the rasterized pattern (33) adapted to the intended pattern generator, the rasterized pattern (33) is further associated with data representing the second raster scaling factor, A rasterization module according to Example 13, characterized in that it is configured as such. [Example 15] A pattern generator (80), comprising a control module (82), An imaging module (84) arranged to draw a pattern in an image area by means of a spatial light modulator (2), wherein the spatial light modulator (2) comprises an array (3) of individually controllable elements (4) arranged to generate an array (20) of elements (22) imaged within an image area (14) on a target surface (10), and the irradiation of the individual imaged elements (22) is controlled by respective ones of said elements (4); an imaging module, The control module (82) is configured to obtain a rasterized pattern (33) having associated data representing a first raster scaling factor that defines scaling in a first direction (101) of the rasterized pattern (33), The control module (82) is further configured to disable elements (4) of the spatial light modulator (2) within the imaging module (84) that are located outside the rasterized pattern (33) in the first direction (101), The imaging module (84) is controlled by the control module (82) and comprises optical means (88) for scaling the rasterized pattern (33) by a first optical scaling factor in the first direction (101) before being drawn in the image area (14), The first optical scaling factor is not 1, Pattern generator. [Example 16] The control module (82) is further configured to obtain the rasterized pattern (33) which further has associated data representing a second raster scaling factor that defines scaling in a second direction (102) of the rasterized pattern (33), the second direction (102) being orthogonal to the first direction (101), The control module (82) is further configured to also disable elements (4) of the spatial light modulator (2) within the imaging module (84) that are located outside the rasterized pattern in the second direction (102), The imaging module (84) is controlled by the control module (82) and includes optical means (88) for further scaling the rasterized pattern (33) in the second direction (102) with a second optical scaling factor before being drawn in the image area (14). The pattern generator according to Example 15, characterized in that.

Claims

1. A method for rasterizing a pattern having a periodic component for a pattern generator based on a spatial light modulator (2), wherein the spatial light modulator (2) is an individually controllable element for generating an array (20) of elements (22) imaged within an image region (14) on a target surface (10). Having an array (3) of (4), the irradiation of each imaged element (22) is controlled by each said element (4), and the rasterization method comprises: Obtaining (S10) an original pattern (30) having pattern items (32) exhibiting periodicity; Determining (S21) a first pattern main period (PM1) in a first direction (101) of the original pattern (30); Obtaining (S31) information regarding a first pitch (D1) of the imaged elements (22) in the first direction (101) of the image region (14) and the intended pattern generator used; Scaling (S41) the original pattern (30) in the first direction (101) by a first raster scaling factor to give a scaled pattern (31), The first raster scaling factor being equal to a value obtained by dividing a first integer multiple of the first pitch (D1) of the pattern generator in the first direction (101) by the first pattern main period (PM1); Cropping (S51) the scaled pattern (31) to include a first integer number of repetitions of the pattern items (32) exhibiting periodicity in the first direction (101) and, if there is an overlap tapering margin covered by the image region (14) in the first direction (101) of the intended pattern generator, including it, to give a rasterized pattern (33) adapted to the intended pattern generator, The rasterized pattern (33) being associated with data representing the first raster scaling factor; A rasterization method comprising.

2. The first principal axis of the array (20) of the imaged elements (22) is rotated at a first angle (α1) with respect to the first direction (101), whereby the first pitch (D1) depends on the distance (d1) between two consecutive ones of the imaged elements (22) along the first principal axis and the first angle (α1). The rasterization method according to claim 1, characterized in that.

3. A step (S22) of determining a second pattern main period (PM2) in a second direction (102) of the original pattern (30), wherein the second direction (102) is orthogonal to the first direction (101), and A step of obtaining (S32) information regarding a second pitch (D2) of the imaged elements (22) in the second direction (102) of the image area (14) and the intended pattern generator used, and Thereby, the step of scaling the original pattern further includes a step (S42) of scaling the original pattern (30) in the second direction (102) with a second raster scaling factor, giving the scaled pattern (31). The second raster scaling factor is equal to a value obtained by multiplying a value obtained by dividing the second pitch (D2) of the pattern generator in the second direction (102) by the second pattern main period (PM2) by a second integer. Thereby, the cropping step further includes a step (S52) of cropping the scaled pattern (31) to include a second integer number of repetitions of the pattern item (32) exhibiting periodicity in the second direction (102) and, if there is an overlap tapering margin covered by the image area (14) in the second direction (102) of the intended pattern generator, also including it, giving the rasterized pattern (33). Thereby, the rasterized pattern (33) is further associated with data representing the second raster scaling factor. The rasterization method according to claim 1 or 2, characterized in that.

4. The second principal axis of the array (20) of the imaged elements (22) is rotated at a second angle (α2) with respect to the second direction (102), whereby the second pitch (D2) depends on the distance (d2) between two consecutive ones of the imaged elements (22) along the second principal axis and the second angle (α2). The rasterization method according to claim 3, characterized in that.

5. The method further comprises obtaining data regarding a first partial overlap exposure number having an equidistant displacement in the first direction (101) of the intended pattern generator, whereby the first raster scaling factor in the scaling step (S41) and the first integer repetition number in the cropping step (S51) are selected such that the value obtained by multiplying the first integer repetition number by the ratio of the first integer and the first partial overlap exposure number is an integer. The rasterization method according to any one of claims 1 to 4, characterized in that.

6. The method further comprises obtaining data regarding a second partial overlap exposure number having an equidistant displacement in the second direction (102) of the intended pattern generator, whereby the second raster scaling factor in the scaling step (S42) and the second integer repetition number in the cropping step (S52) are selected such that the value obtained by multiplying the second integer repetition number by the ratio of the second integer and the second partial overlap exposure number is an integer. The rasterization method according to claim 3 or 4, or, if dependent on claim 3 or 4, the rasterization method according to claim 5, characterized in that.

7. The first raster scaling factor is selected to be as close to 1 as possible, taking into account any constraints in the selection of the first integer and the first integer repetition number, and The second raster scaling factor is selected to be as close to 1 as possible, taking into account any constraints in the selection of the second integer and the second integer repetition number, The rasterization method according to claim 3 or 4, characterized by comprising at least one of.

8. A method of drawing a pattern having a periodic component for a pattern generator based on a spatial light modulator (2), wherein the spatial light modulator (2) is arranged to generate an array (20) of individually controllable elements (4) arranged to generate an array (22) of elements imaged within an image region (14) on a target surface (10), the irradiation of each imaged element (22) being controlled by the respective element (4), the drawing method comprising: Obtaining (S61) the rasterized pattern having associated data representing a first raster scaling factor that defines scaling in a first direction (101) of the rasterized pattern (33); Disabling (S62) the elements (4) of the spatial light modulator (2) in the pattern generator that are located outside the rasterized pattern in the first direction (101); Drawing (S80) the rasterized pattern on an image region (14) on the target surface (10), including: The drawing (S80) includes scaling (S81) with a first optical scaling factor in the first direction (101); The first optical scaling factor is not 1; Drawing method.

9. The drawing method according to claim 8, characterized in that the first optical scaling factor is equal to the reciprocal of the first raster scaling factor.

10. The rasterized pattern is further associated with data representing a second raster scaling factor that defines scaling in a second direction (102) of the rasterized pattern (33), the second direction (102) being orthogonal to the first direction (101), The step of disabling the elements (4) of the spatial light modulator (2) further comprises disabling (S72) the elements (4) of the spatial light modulator (2) of the pattern generator that are located outside the rasterized pattern in the second direction (102), Thereby, the drawing (S80) further includes scaling (S82) with a second optical scaling factor in the second direction (102). The drawing method according to claim 8 or 9, characterized by the above.

11. Both the first optical scaling factor and the second optical scaling factor are not 1 and reach the image area. The drawing method according to claim 10, characterized in that.

12. The drawing method according to claim 10 or 11, characterized in that the second optical scaling factor is equal to the reciprocal of the second raster scaling factor.

13. A rasterizing module (60) for a pattern generator based on a spatial light modulator (2), wherein the spatial light modulator (2) is arranged to generate an array (20) of individually controllable elements (4) arranged to generate an array (20) of elements (22) imaged within an image area (14) on a target surface (10), the irradiation of each imaged element (22) being controlled by a respective one of said elements (4), said rasterizing module (60) comprising: A processor (62); And a memory (64). The memory (64) includes instructions executable by the processor (62), whereby the rasterizing module (60): Obtains an original pattern (30) having a pattern item (32) exhibiting periodicity; Determines a first pattern main period (PM1) in a first direction (101) of the original pattern (30); Obtains information regarding the first pitch (D1) of the imaged elements (22) in the first direction (101) of the image area (14) and the intended pattern generator used; Scales the original pattern (30) in the first direction (101) by a first raster scaling factor to provide a scaled pattern (31); The first raster scaling factor is equal to a value obtained by dividing an integer multiple of the first pitch (D1) of the pattern generator in the first direction (101) by the first pattern main period (PM1); The scaled pattern (31) is cropped to include an integer number of repetitions of the first of the pattern items (32) exhibiting periodicity in the first direction (101) and, if there is an overlap tapering margin covered by the image area (14) in the first direction (101) of the intended pattern generator, to include it, to provide a rasterized pattern (33) adapted to the intended pattern generator. The rasterized pattern (33) is associated with data representing the first raster scaling factor. A rasterization module (60) characterized by being configured as such. **Claim 14** The memory (64) further includes instructions executable by the processor (62), whereby the rasterization module (60) further determines a second pattern main period (PM2) in a second direction (102) of the original pattern (30), the second direction (102) being orthogonal to the first direction (101), acquires information regarding the second pitch (D2) of the imaged element (22) in the second direction (102) of the image area (14) and the intended pattern generator used, scales the original pattern (30) in the second direction (102) by a second raster scaling factor to give the scaled pattern (31), the second raster scaling factor being equal to a value obtained by dividing twice the second pitch (D2) of the pattern generator in the second direction (102) by the second pattern main period (PM2), crops the scaled pattern (31) to include a second integer number of repetitions of the pattern item (32) exhibiting periodicity in the second direction (102) and, if there is an overlap taper margin covered by the image area (14) of the intended pattern generator in the second direction (102), includes it, to give the rasterized pattern (33) adapted to the intended pattern generator, the rasterized pattern (33) is further associated with data representing the second raster scaling factor. The rasterization module according to claim 13, characterized by being configured as such. **Claim 15** A pattern generator (80), comprising a control module (82), An imaging module (84) arranged to draw a pattern in an image area by means of a spatial light modulator (2), wherein the spatial light modulator (2) is arranged to generate an array (20) of individually controllable elements (4) arranged to generate an array (22) of elements imaged within an image area (14) on a target surface (10), and the irradiation of the individual imaged elements (22) is controlled by respective ones of said elements (4); an imaging module, The control module (82) is configured to obtain the rasterized pattern (33) having associated data representing a first raster scaling factor that defines scaling in a first direction (101) of the rasterized pattern (33). The control module (82) is further configured to disable the elements (4) of the spatial light modulator (2) within the imaging module (84) that are located outside the rasterized pattern (33) in the first direction (101). The imaging module (84) is controlled by the control module (82) and comprises optical means (88) for scaling the rasterized pattern (33) by a first optical scaling factor in the first direction (101) before being drawn in the image area (14). The first optical scaling factor is not 1. Pattern generator.

16. The control module (82) is further configured to obtain the rasterized pattern (33) which further has associated data representing a second raster scaling factor that defines scaling in a second direction (102) of the rasterized pattern (33), the second direction (102) being orthogonal to the first direction (101). The control module (82) is further configured to also disable the elements (4) of the spatial light modulator (2) within the imaging module (84) that are located outside the rasterized pattern in the second direction (102). The imaging module (84) is controlled by the control module (82) and includes optical means (88) for further scaling the rasterized pattern (33) in the second direction (102) with a second optical scaling factor before being drawn in the image area (14). The pattern generator according to claim 15, characterized in that.

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