Method and system for generating linewidth optimized patterns - Patents.com

Abstract

A method for obtaining linewidth correction data for a workpiece patterning device comprises printing (S2) a calibration pattern with an exposure beam sweepable in a sweep direction. The calibration pattern has a plurality of exposed and unexposed lines extending in the sweep direction and having different linewidths and different distances to adjacent lines. The linewidths are measured (S4). A deviation in the measured linewidths is calculated (S6). Linewidth correction data is calculated (S8) for adapting the linewidths of the pattern printing data before printing to compensate for the calculated deviations. The linewidth correction data is associated with at least the intended linewidth and information as to whether the line is an exposed or unexposed line. A method for calibrating printing data and a method and system therefor are also disclosed.

Description

[Technical field]

[0001] The present technology relates to pattern printing and an apparatus therefor, and in particular to a method for obtaining a correction pattern for a patterning device on a workpiece, a method for calibrating print data, and a method and an apparatus for printing a pattern. [Background technology]

[0002] In today's semiconductor industry, masks produced by laser-based mask writers are commonly used for the production of various types of advanced chips and imaging devices. For example, direct writing for electronic packaging has also become standard today. In the last few years, the production of larger and more precise displays has also increased dramatically. Therefore, the microlithography printing process needs to become faster, more accurate, and less expensive.

[0003] In the field of microlithography printing processes, a mask writer or direct writer may be based on a print head providing one or more precision laser beams. The print head and the substrate intended to be written on can be moved relative to each other by moving either the print head or the substrate or both. By varying the power of the laser beams in coordination with the relative movement, an exposure pattern can be written on the substrate.

[0004] The accuracy of printing is very important. Deviations from the intended pattern, e.g., critical dimensions (CD) or critical dimension linearity (CDL), or positioning errors, even in the range of a few nanometers to a few hundred nanometers, can be detrimental to or degrade the final result. Such printing errors are usually caused by imperfections in the mechanical and / or optical properties of the print head.

[0005] In published U.S. patent U.S. Pat. No. 7,919,218, a method for a multiple exposure beam lithography tool is disclosed. A method is described for patterning a workpiece coated with a layer sensitive to electromagnetic radiation by simultaneously using multiple exposure beams. It is determined whether any beam has an actual position relative to a reference beam that differs from its intended position. If a mispositioned beam prints at the edge of a feature, an adjustment is made to the exposure dose of that beam.

[0006] Although such corrections are designed to correct for errors in beam position, deviations from the intended pattern may be due to many other reasons that cannot be corrected by such exposure adjustments.

[0007] In published WO 2021 / 254726, a method for obtaining a correction pattern for a workpiece patterning device is disclosed. A calibration pattern is printed by a plurality of simultaneously operating exposure beams that can be swept in a second direction according to calibration pattern printing data having a number of edges. The positions of the edges are measured. Deviations of the measured positions relative to the calibration pattern are calculated. Each deviation is associated with the exposure beam used, the sweep position and the grid fraction position. Edge correction data is calculated for adapting the edge representation of the pattern printing data before printing in order to correct the calculated deviations. The edge correction data depends on the exposure beam used, the sweep position and the grid fraction position.

[0008] Although such corrections are designed to correct for CD errors, CDL deviations may still exist. Summary of the Invention [Problem to be solved by the invention]

[0009] The general objective of this technique is to improve critical dimension linearity. [Means for solving the problem]

[0010] The above object is achieved by a method and an arrangement according to the independent claims. Preferred embodiments are defined in the dependent claims.

[0011] That is, in a first aspect, a method for obtaining line width correction data of a workpiece patterning device comprises printing a calibration pattern using an exposure beam sweepable in a sweep direction. The printing is performed according to printing data of the calibration pattern. The calibration pattern has a plurality of exposed and unexposed lines extending in the sweep direction and having different line widths and different distances to adjacent lines. A line width of the line in a scanning direction perpendicular to the sweep direction of the printed calibration pattern is measured. A deviation of the measured line width of the line relative to an intended line width of the line is calculated according to the printing data of the calibration pattern. Based on the calculated deviation, line width correction data is calculated. The line width correction data is for adapting the line width of the pattern printing data before printing to compensate for the calculated deviation. The line width correction data is associated with at least the intended line width and information on whether the line is an exposed or unexposed line.

[0012] In a second aspect, a method for obtaining line width compensated print data comprises obtaining print data for a pattern to be printed. Lines in a sweep direction of the pattern to be printed are identified. Line characteristics of the lines are determined. The line characteristics include at least a line width and information on whether the line is an unexposed line or an exposed line. A line width adjustment value for each of the identified lines is estimated from the line width correction data. The line width correction data is obtained by the method according to the first aspect based on the determined line width and the information on whether the line is an unexposed line or an exposed line. Print data defining the identified lines is adapted to the line width compensated print data according to the line width adjustment value.

[0013] In a third aspect, a method for printing a pattern comprises obtaining line width corrected printing data associated with the pattern to be printed by a method according to the second aspect, and a printing process of a workpiece coated with a layer sensitive to electromagnetic or electron radiation is controlled based on the line width corrected printing data.

[0014] In a fourth aspect, a system for obtaining linewidth correction data for a workpiece patterning device comprises a printing device, a measurement device, and a processing device. The printing device is configured to create a calibration pattern using an exposure beam sweepable in a sweep direction. The printing device is configured to perform printing according to the calibration pattern printing data. The calibration pattern has a plurality of exposed and unexposed lines extending in the sweep direction and having different linewidths and different distances to adjacent lines. The measurement device is arranged to measure linewidths of the lines in a scan direction perpendicular to the sweep direction of the printed calibration pattern. The processing device is configured to calculate a deviation of the measured linewidth of the line relative to an intended linewidth of the line according to the calibration pattern printing data. The processing device is further configured to calculate, based on the calculated deviation, linewidth correction data for adapting the linewidth of the pattern printing data prior to printing to compensate for the calculated deviation. The linewidth correction data is associated with at least the intended linewidth and information on whether the line is an exposed or unexposed line.

[0015] In a fifth aspect, an apparatus for processing print data defining a pattern to be printed comprises a processing circuit and a memory. The memory comprises instructions executable by the processing circuit, whereby the processing circuit is operative to obtain print data of the pattern to be printed. The processing circuit is further operative to identify lines in a sweep direction of the pattern to be printed. The processing circuit is further operative to determine line characteristics of the lines. The line characteristics include at least a line width and information whether the line is an unexposed line or an exposed line. The processing circuit is further operative to estimate a line width adjustment value for each of the identified lines from the line width correction data obtained by the method according to the first aspect based on the determined line width and the information whether the line is an unexposed line or an exposed line. The processing circuit is further operative to adapt the print data defining the identified lines to the line width corrected print data according to the line width adjustment value.

[0016] In a sixth aspect, a printing apparatus comprises a line width correction print data processing device, a print head, and a control device. The line width correction print data is obtained by the device for processing print data according to the fifth aspect. The printing apparatus is a printing apparatus of a system for obtaining a correction pattern for a workpiece patterning device according to the fourth aspect. The print head has an exposure beam sweepable in a sweep direction. The control unit is arranged to control the operation and relative motion of the print head based on the line width correction print data.

[0017] One advantage of the proposed technique is that the correction of the data is highly reproducible and can be calibrated by linearity measurements. Thus, the proposed technique can be adjusted to all conditions and system types. Recalibration can be performed by new measurements. [Brief description of the drawings]

[0018] The invention together with further objects and advantages thereof will be best understood by reference to the following description taken together with the accompanying drawings, in which:

[0019] [Figure 1] FIG. 1 shows a schematic diagram of a printing apparatus. [Diagram 2] FIG. 2 shows printing using a micro-exposure beam. [Diagram 3] FIG. 3 is a diagram showing critical dimension linearity measurement. [Figure 4] FIG. 4 shows a schematic of a printing apparatus having multiple exposure beams. [Diagram 5] FIG. 5 shows printing using multiple exposure beams and micro-swipes. [Figure 6] FIG. 6 is a flow diagram of steps in one embodiment of a method for obtaining a compensation pattern for a workpiece patterning device. [Figure 7A] FIG. 7A shows a schematic of an exposure line. [Figure 7B] FIG. 7B shows a schematic of the unexposed lines. [Figure 8]FIG. 8 is a diagram illustrating the relationship between the intended line width and the corrected line width. [Figure 9] FIG. 9 is a flow diagram of steps of one embodiment of a method for calibrating print data. [Figure 10] FIG. 10 is a diagram illustrating intensity adjustment in a bitmap region. [Figure 11] FIG. 11 is a diagram illustrating the relationship between intended line width and line width correction. [Figure 12] FIG. 12 is a flow diagram of steps of one embodiment of a method for printing a pattern. [Figure 13A] FIG. 13A shows a schematic of dense exposure lines. [Figure 13B] FIG. 13B shows a schematic of dense unexposed lines. [Figure 14] FIG. 14 is a schematic diagram of one embodiment of a system for obtaining a compensation pattern for a workpiece patterning device. [Figure 15A] FIG. 15A is a schematic diagram of one embodiment of an apparatus for processing print data that defines a pattern to be printed. [Figure 15B] FIG. 15B is a schematic diagram of one embodiment of an apparatus for processing print data that defines a pattern to be printed. [Figure 16] FIG. 16 is a schematic diagram of one embodiment of a printing device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Throughout the drawings, the same reference numbers are used for similar or corresponding elements.

[0021] To better understand the proposed technology, it is useful to begin with an overview of a printing system with microsweep capabilities.

[0022] 1 shows diagrammatically a printing apparatus 1 comprising a table 10 on which a workpiece support 12 is arranged. The workpiece support 12 is movable in a direction Y relative to the table 10. A workpiece 20 is rigidly mounted on the workpiece support 12. The surface of the workpiece 20 is provided with a layer that is sensitive to electromagnetic waves or particle beams.

[0023] The printing apparatus 1 further comprises a workpiece patterning device 2. The workpiece patterning device 2 comprises a stand 30 supporting a print head 32. The print head 32 is movable in a direction X along the stand 30. The print head 32 is arranged to provide an exposure beam 34 for exposure with electromagnetic or particle radiation, which exposure beam 34 is directed towards the workpiece 20.

[0024] The combination of movement of the workpiece support 12 and the print head 32 allows a small sweep of the exposure beam 34 to reach all areas on the workpiece 20 that are to be irradiated, as will be further described below. In the figure, exposed areas 24 and unexposed areas 22 are shown.

[0025] As will be appreciated by those skilled in the art, the relative mechanical motion can be achieved in other ways in other embodiments, such as, for example, in a manner in which the print head 32 is movable in two dimensions and / or in a manner in which the workpiece support 12 is movable in two dimensions.

[0026] In this type of printing apparatus, a small sweep of the exposure beam is used. Figure 2 shows this diagrammatically. By sweeping the beam a small distance in a direction perpendicular to the main direction of movement of the print head, the width of the printed strip is increased and the overall printing speed is also increased. A portion of a workpiece 20 is shown. At the illustrated instant, the exposed areas 24 are shown hatched and the unexposed areas 22 are shown without hatching, with the understanding that the actual degree of exposure also depends on the intensity of the exposure beam at each location. However, in this figure, the "exposed areas" 24 are the areas through which the exposure beam 34 has passed or should pass when the intensity applied at that instant.

[0027] From this, it can be seen that the accuracy characteristics of the patterns in the X and Y directions are governed in part by different device characteristics. The accuracy in the Y direction depends heavily on, for example, the accuracy of the control of the intensity variation during the micro sweep or the uniformity of the micro sweep speed. The accuracy in the X direction depends on the accuracy of the print head motion and the repeatability of the micro sweep conditions.

[0028] One of the most important characteristics of a pattern printing system is the X and Y CD linearity. CD linearity is defined as the linewidth deviation measured as a function of pattern linewidth. A characteristic of today's typical mask printer or direct printer systems is that X linearity degrades before Y linearity. This sets the practical resolution for the production writer system.

[0029] 3 shows the CD linearity in X and Y directions of a conventional pattern printer. The square connected to curve 101 represents the CD in Y direction, and the star connected to curve 102 represents the CD in X direction. Here, it can be seen that when the line width becomes smaller than about 500 nm, the X curve 102 drops off sharply while the Y curve 101 is virtually unaffected. However, the behavior in the X direction changes, which is not useful for stable characteristics in the Y direction.

[0030] Additionally, it has been found that the CD linearity profile differs depending on whether the line is an exposed line or an "unexposed line," ie, a line with no exposure.

[0031] It has also been found that the curves change depending on how closely spaced the lines are, so isolated lines may have a different CD linearity profile than lines in the vicinity of other lines.

[0032] One source of these nonlinearities is believed to be related to the intensity distribution of the exposure beam. For a spot on the substrate to behave as if it was exposed, the light intensity must exceed a certain threshold. However, the edges of the exposure beam are not sharp, and the spatial distribution of light varies continuously throughout the beam. Spots on the substrate that are exposed with an intensity below the threshold are expected to be etched away in the next manufacturing step. However, if adjacent spots are highly illuminated, the sum of the "stray" intensities can exceed the threshold and the spot will behave as if it was exposed. Thus, for very narrow structures, the exposure pattern of adjacent spots can give unpredictable variations in the area where "exposure" is considered to have occurred. This results in a CD linearity profile that varies with line width and line characteristics, i.e. exposed or unexposed lines.

[0033] In many pattern printers, multiple beams are used at the same time. By using a print head with multiple beams for simultaneous exposure, the overall speed can be increased. Figure 4 shows a schematic of a printing apparatus 1 in which a print head 32 is arranged to provide multiple exposure beams 34. The exposure beams 34 are usually micro-swept in synchronism with each other, as indicated by the double arrows.

[0034] This is illustrated diagrammatically in Figure 5. A portion of a workpiece 20 is shown, where at the illustrated instant the exposed areas 24 are shown by hatching and the unexposed areas 22 are shown without hatching.

[0035] In the figure, five exposure beams 34A-34E are shown. As will be appreciated by those skilled in the art, the number of exposure beams can be selected depending on, for example, the required printing speed, the available exposure beam size, the overall complexity, etc. However, in this exemplary figure, five exposure beams 34A-34E have been selected to allow an easily discernible explanation of the printing principles.

[0036] In this figure, a print head (not shown) can be moved in steps in the X direction, which faces downwards in the figure. The print head moves regular distances, which are shown as exposure beam steps 50. At each position, the exposure beam is swept in so-called micro-sweeps along the Y direction, which faces upwards in the figure, in order to cover a sweep width 52. In the illustrated example, the micro-sweep is performed at approximately half the position of the micro-sweep. After the micro-sweep is finished, the print head is moved in the X direction by another exposure beam step 50 and a new micro-sweep is performed. As can be seen, when all the exposure beams pass a given X position, the entire surface of the workpiece is exposed (or can be exposed). The different exposure beams are therefore planned to fill each other's intervals in order to build up an exposure of the entire surface. The exposure beam width 56 corresponds to the width of the microstripes exposed during the micro-sweep, and to cover the entire surface, the exposure beam width 56 times the number of exposure beams is equal to the exposure beam step 50. It can be seen, however, that the exposure beam distance interval 54 is different from the exposure beam step 50.

[0037] In another embodiment, the print head is moved continuously, and the micro sweep is initiated when the print head is at the correct position for the micro sweep to begin. As a result of the continuous movement, the relative position between the stage and the print head changes during the micro sweep. This can usually be compensated for in various ways, for example by performing the micro sweep at a small angle to the normal to the direction of movement, usually referred to as the azimuth angle, ultimately producing a sweep perpendicular to the stage. Such an arrangement is implemented, for example, by angled sweep optics, and is well known in the art.

[0038] The movement of the print head is planned so that the different exposure beams cover the entire surface of the workpiece 20 .

[0039] It has been found that the above CD linearity characteristics are essentially independent of whether a single exposure beam or multiple exposure beams are used to print the lines.

[0040] CD linearity is expected to be affected by many different measures. This may include, for example, improving the laser spot, laser and optical alignment, minimizing stray light, using the best resists and lithography processes. However, most of these factors have improved over the years, so further improvements would require extreme measures, for example with regard to alignment, which would be costly and require frequent recalibration procedures.

[0041] Therefore, in the present disclosure, as an alternative or further improvement to such CD linearity improvement measures, modification of pattern data in the pixel domain may be used to improve linearity in the X direction, allowing thinner lines to be resolved with linearity within specifications, which can be of great value to users.

[0042] FIG. 6 is a flow diagram of steps of an embodiment of a method for obtaining a correction pattern of a workpiece patterning device. In step S2, a calibration pattern is printed using an exposure beam that can be swept in a sweep direction. The printing is performed according to the printing data of the calibration pattern. The calibration pattern has a number of exposed and unexposed lines extending in the sweep direction and having different line widths and different distances to adjacent lines. The line widths preferably range from the smallest possible line width that can be obtained with the printer used to a line width that is sufficient for the ends to be considered independent of each other. For example, in a system used to obtain the curve of FIG. 3, it may be interesting to correct line widths between 200 nm and 600 nm, in such a case the line widths of the calibration pattern should cover at least this range.

[0043] In step S4, the line width of the line is measured in a scan direction perpendicular to the sweep direction of the printed calibration pattern. In step S6, a deviation of the measured line width relative to the edge line width is calculated according to the printing data of the calibration pattern. In step S8, based on the calculated deviation, line width correction data is calculated. The line width correction data is for adapting the line width of the pattern printing data before printing to correct the calculated deviation. The line width correction data is associated with at least the intended line width and information on whether the line is an exposed or unexposed line.

[0044] Figures 7A and 7B show different options: Figure 7A shows an exposed line 110, which is surrounded in the X-direction by an unexposed area 112 and is associated with a predefined width 114. Figure 7B similarly shows an unexposed line 116, which is surrounded in the X-direction by an exposed area 118 and is associated with a predefined width 114.

[0045] There are various types of photoresist. When using a photoresist that remains after etching when irradiated, the exposed areas become "dark fields" and the unexposed areas become "clear fields". In this disclosure, unless otherwise stated, this type of photoresist is used as the exemplary choice. However, when using a photoresist that etches when irradiated, the exposed areas become "clear fields" and the unexposed areas become "dark fields". The ideas of the present invention are applicable to either choice.

[0046] For each measured linewidth, at least two different CD linearity curves are obtained, one for the exposed line and one for the unexposed line.

[0047] If it turns out that a line of a given intended line width always prints with another line width, such non-linearity can be corrected. If the printed line width is measured to be smaller than intended, the original print data can be pre-corrected by requesting a somewhat wider line width. Similarly, if the printed line width is measured to be larger than intended, the original print data can be pre-corrected by requesting a somewhat narrower line width. In such a case, the finally printed line can assume the originally intended line width. Correction data can be determined. FIG. 8 shows a non-linearity correction curve 120 for an exposure line. This curve behaves inversely with respect to the measured CD linearity. An intended line width 122 is related to a line width 124 corrected by this curve. Thus, the curve 120 is an example of line width correction data. The line width correction data can also be provided in other ways, for example as a look-up table in which the intended line width is used as an entrance value.

[0048] 9 is a flow diagram of steps of an embodiment of a method for calibrating print data. In step S10, print data of a pattern to be printed is obtained. In step S12, lines in the sweep direction of the pattern to be printed are identified. In step S14, line characteristics of the lines are determined. The line characteristics include at least the line width and whether the line is an exposed line or an unexposed line. In step S16, a line width adjustment value for each of the identified lines is estimated from the line width correction data obtained by the method according to the above description. The estimation is based on the determined line width and whether the line is an unexposed line or an exposed line. In step S18, the print data defining the identified lines is adapted according to the line width adjustment value. This adaptation results in print data with corrected line widths.

[0049] When printing a pattern, the print data is often provided in the vector domain. This is usually converted to the bitmap domain, where a raster of pixels is defined in relation to their individual intensities. When the exposure is performed, the exposure beam moves according to the pixels, and the exposure intensity of each of the pixels is controlled to correspond to the associated intensity value.

[0050] The adaptation of the print data may be performed in the bitmap area. Figure 10 shows a schematic representation of a portion of the bitmap print data, where various pixels 90 are defined by dotted lines. The original bitmap print data is shown in the left portion of the figure. An unexposed line 116 having an intended line width 114 is surrounded by an exposed area 118. The intended end 84 of the unexposed line 116 does not coincide exactly with a pixel boundary, and to achieve an exposure that is somewhat offset from the pixel boundary, the associated intensities of the pixels surrounding the unexposed line end 84 are adjusted to cause a misalignment, where the exposure reaches a level where the position is considered to be exposed. The third pixel column from the right is given a low intensity because the intended end 84 is located just inside the right pixel boundary. The use of such intensity variations to displace a pattern end from a pixel boundary by a distance less than the width of a pixel is well known to those skilled in the art and will not be discussed or described further.

[0051] According to the linewidth adjustment concept further presented above, adjusted linewidths are useful. In the illustrated embodiment, such adjusted linewidths are defined by adjusted line ends 85. This calls for the ends of the lines to be adjusted by amounts Δ1 and Δ2, respectively. The sum of Δ1 and Δ2 corresponds to the estimated linewidth adjustment amount. In other words, the intensity of the individual bits at or immediately adjacent to each of the adjusted line ends is adjusted such that the sum of each of the lineend position adjustments is equal to the estimated linewidth adjustment amount.

[0052] The adjusted linewidth corrected print data is shown in the right part of Figure 10, where the associated intensities are adapted to correspond to the adjusted line ends 85, thereby obtaining the adjusted linewidth 86.

[0053] The edge adjustments are added to the total estimated linewidth adjustment. Preferably, half the estimated linewidth adjustment is applied at each edge. However, in other embodiments, a different division can be applied. The division may depend, for example, on the imbalance of exposure density at each edge neighborhood.

[0054] When measuring the linewidth nonlinearity, multiple discrete values ​​of the linewidth are used. Linewidth correction data is estimated from measurements of these discrete values ​​of the linewidth. This can be, for example, a linewidth correction value assigned to a set of discrete linewidth values ​​or a continuous linewidth correction curve. A set of discrete linewidth correction values ​​is advantageous when using, for example, a lookup table.

[0055] FIG. 11 shows a diagram of determining a set of discrete linewidth correction values ​​121. These values ​​may be valid for exposed or unexposed lines, and may also be valid for a particular proximity index, as will be further described below. For an intended linewidth that corresponds exactly to these discrete linewidth correction values ​​121, the choice is obvious. If the intended linewidth is between the discrete values, a different approach can be used. One alternative is to determine the closest linewidth for which the determined discrete linewidth correction value 121 lies and use that value. This is indicated by the short dashed line 126.

[0056] Another alternative is to use interpolation. Thus, in one embodiment, estimating the linewidth adjustment value involves interpolation using linewidth adjustment values ​​from the linewidth correction data corresponding to the nearest large linewidth and the nearest small linewidth.

[0057] This is indicated by the dotted line 123. The interpolation may be linear or may follow other interpolation techniques known to those skilled in the art.

[0058] When the line width compensation print data is available, the printing process may be started. Figure 12 is a flow diagram of steps of an embodiment of a pattern printing method. In step S20, line width compensation print data of a pattern to be printed is obtained. The line width compensation print data is obtained according to the method described in the present disclosure. In step S22, the printing process of a workpiece, at least a portion of which is coated with a layer sensitive to electromagnetic or electronic radiation, is controlled based on the line width compensation print data.

[0059] As indicated above, the use of multiple exposure beams is common, and thus in one embodiment, the step S22 of controlling the printing process comprises controlling simultaneously operating exposure beams during scanning in a scan direction perpendicular to the sweep direction to provide micro-sweeps in said sweep direction, thereby creating a scan strip.

[0060] In another embodiment, the step S22 of controlling the printing process further comprises creating a plurality of such scan strips offset in a second direction.

[0061] The printing process may be a microlithography printing process. In different embodiments, the printing process may be a mask writing process or a direct writing process.

[0062] One of the factors that causes linewidth non-linearity is the effect of the intended radiation exposure on neighbouring or at least closely located pixels. Such "unintended" radiation contributes to the background radiation level and affects the position of the edges of the printed lines. This is one of the important reasons why the line correction is different for exposed and unexposed lines. However, the general background radiation level may also be advantageously taken into account. In a preferred embodiment, an additional use of a proximity factor is applied.

[0063] In FIG. 7A, an exposure line 110 is shown. Since the exposure line 110 is surrounded by a large unexposed area 112, the exposure line 110 may be considered a separated exposure line 110. In FIG. 13A, an exposure line 110B is shown having a line width 114, but with limited surrounding unexposed area 112. Thus, there are other exposure areas 111 within a not too far distance 119 from the exposure line 110B. Such an exposure line 110B may be considered a dense exposure line. Background radiation levels from adjacent exposure areas 111 may affect the actual printed line width of the exposure line 110B.

[0064] Figure 13B similarly shows a dense unexposed line 116B having a line width 114, with other unexposed regions 117 within a relatively close distance 119. In contrast, Figure 7B shows isolated unexposed lines 116.

[0065] In one embodiment, a proximity indicator is used to determine the line width adjustment. As shown in FIG. 6, the method for obtaining a correction pattern for a workpiece patterning device may comprise an additional step S7. In step S7, a proximity indicator for each of the lines of the calibration pattern is determined. The proximity indicator is a parameter that represents a relationship between exposed or unexposed areas around the lines of the calibration pattern. Thus, the line width correction data is further related to the proximity indicator.

[0066] In the method of calibrating the print data, the proximity indicator can be used to further refine the adjustment of the line width. Thus, in one embodiment, the line characteristics further include a proximity indicator. The proximity indicator is a parameter that represents the average percentage of exposed or unexposed area around the line. The line width correction data is further associated with the proximity indicator.

[0067] In one embodiment, the proximity metric is a line density classification having at least two classes, which may be, for example, dense lines and isolated lines, and separate linewidth corrections are achieved for dense exposed lines, isolated exposed lines, dense unexposed lines, and isolated unexposed lines.

[0068] In one embodiment, the proximity index is a line density index. Such a line density index may be the ratio of the distance 119 to the nearest neighbor line to the line width 114. This ratio may be evaluated bilaterally or unilaterally and then applied to each side separately or as an average of both sides.

[0069] Such line density measurements may in some embodiments be divided into two or more ranges for classification when estimating line width adjustment values, while in other embodiments estimating the line width adjustment value may include interpolation using width adjustment values ​​from the line width correction data corresponding to the nearest large and nearest small line density measurements.

[0070] In one embodiment, a "completely separated line" range can be considered to exist if the ratio is 5 or greater. A range greater than 2 but less than 5 can be labeled "slightly dense," a range greater than 1 but less than or equal to 2 can be labeled "moderately dense," and a range less than or equal to 1 can be labeled "very dense."

[0071] This proximity measure as a ratio of distance to linewidth is an approximation. It assumes that the linewidth influence always comes only from the nearest neighbors on each side. However, this is a useful and typical approximation. The most typical case is when the linewidth and neighbor distance in a given area remain constant for a significant number of iterations in the evaluated direction.

[0072] It can be said that the above-mentioned proximity index corresponds to a parameter that represents the average ratio of exposed and unexposed areas in the surroundings. The density ratio is one of the common ways to express this, but it should be understood that this average is only taken into account in the vertical direction.

[0073] The proximity index defined in the above manner fits well with the typical method of measuring and evaluating CD linearity. Two 2-dimensional lookup tables are added. For each measured line, the line width in the data representation and the distance to the nearest neighbor in the data representation give a dense ratio, typically as a decimal value.

[0074] In one embodiment, exposed lines select a first lookup table and unexposed lines select a different lookup table. For a discrete number of line widths there is a discrete number of measured dense ratio correction values. A linear or bipolar linear interpolation is applied in both of these dimensions. In other words, a linear interpolation is performed between the closest line widths and also between the closest dense ratio values.

[0075] As mentioned above, the density ratio may be evaluated on one or both sides, and the correction may be the same value on both sides, i.e., half on each side, or may be applied on each side as a value calculated to best correct for the effect of adjacent lights on each side.

[0076] In one implementation of the ideas disclosed above, we employ a novel table-based linewidth correction for the narrowest linewidth in the X direction. The implementation is based on one-dimensional edge detection in the pattern data with no optical proximity effect, and suggests a sliding window of pixel data of approximately 7-10 small sweeps of data.

[0077] This is possible before or after other types of corrections, e.g., CD correction or corner enhancement, while still using the same basic techniques. Even if the required changes are characteristic, they require only easily performed adaptations, thereby limiting the implementation costs.

[0078] By using a sliding window of size 7, lines as thin as the sliding window size minus 2, or 5 pixels, can be corrected. Each edge can be corrected to plus or minus 1 pixel. In a system with a pixel size of 170 nm, this means that lines narrower than 850 nm in X can be corrected down to a 1 pixel line, which is typically well below practical resolution. An example of a sliding window routine is shown in Appendix A.

[0079] As mentioned above, for photoresists that are etchable upon illumination, corrections can be made for both clear field lines (exposed on an unexposed background) or dark field lines (unexposed lines on an exposed background). The correction tables can be created using a combination of linearity model data based on simulations and linearity measurements.

[0080] Figure 14 shows a schematic representation of an embodiment of a system 70 for obtaining a correction pattern for a workpiece patterning device. The system 70 for obtaining a correction pattern for a workpiece patterning device comprises a printing apparatus 1 configured to create a calibration pattern using an exposure beam that can be swept in a sweep direction. An example of such a printing apparatus 1 is also shown in Figures 1 and 4. The printing apparatus 1 is configured to perform printing according to printing data of a calibration pattern. This calibration pattern comprises a number of exposed and unexposed lines extending in the sweep direction and having different line widths and different distances to adjacent lines.

[0081] The system 70 for acquiring a correction pattern for a workpiece patterning device further comprises a measurement device 4 arranged to measure the linewidth of lines in a scan direction perpendicular to the sweep direction of the printed calibration pattern. In the figures, the measurement device 4 is shown as a separate unit arranged on the stand 30 of the printing apparatus 1. However, the measurement device 4 may also be provided as a completely separate unit or as an integral part of the print head 32. Such measurement devices 4 are well known in the art and are available in many different configurations. However, details of the measurement device 4 are not essential and will not be described further, so long as the measurement device provides data from which the linewidth of lines in the scan direction or such end positions can be estimated.

[0082] The system 70 for obtaining a correction pattern for a workpiece patterning device further comprises a processing device 6. The processing device 6 is connected to the printing device 1 as well as the measurement device 4. The processing device 6 is configured to calculate the deviation of the line width of the measured lines relative to the intended line width of the edges according to the calibration pattern printing data.

[0083] The processing device 6 is further configured to calculate, based on the calculated deviation, line width correction data for adapting a line width of the pattern printing data before printing to compensate for the calculated deviation, the line width correction data being associated with at least an intended line width and information as to whether the line is an exposed or unexposed line.

[0084] In one embodiment, the processing device is further configured to determine a proximity indicator for each line of the calibration pattern, the proximity indicator being a parameter representative of an average percentage of exposed or unexposed area around the line of the calibration pattern, and the line width correction data is further associated with the proximity indicator.

[0085] In one embodiment, the proximity measure is a linear density classification having at least two classes.

[0086] In another embodiment, the proximity index is a line density index.

[0087] FIG. 15A illustrates in schematic form an embodiment of an apparatus 80 for processing print data defining a pattern to be printed. The apparatus 80 for processing print data defining a pattern to be printed comprises a processing circuit 8 and a memory 7. The memory 7 includes instructions executable by the processing circuit 8, whereby the processing circuit 8 is operative to obtain print data of the pattern to be printed and identify lines in a sweep direction of the pattern to be printed. When the instructions are executed by the processing circuit 8, the processing circuit 8 is operative to further determine line characteristics of the lines and to estimate a line width adjustment value for each of the identified lines from the line width correction data. The line characteristics include at least a line width and whether the line is an unexposed line or an exposed line. The line width correction data is obtained by a method according to the above description and is based on at least a line width and whether the line is an unexposed line or an exposed line. When the instructions are executed by the processing circuit 8, the processing circuit 8 is operative to further adapt the print data defining the identified lines according to the line width adjustment value to the line width correction print data. The line width correction data is obtained, for example, by a system 70 for obtaining a correction pattern according to the embodiment of FIG. 14.

[0088] In one embodiment, processing circuitry 8 operates to adapt the print data in a bitmap domain: the intensities of individual bits at or adjacent to each of the line ends to be adjusted are adjusted to achieve a sum of each of the line end position adjustment values ​​equal to the amount of the estimated line width adjustment value.

[0089] In one embodiment, the processing circuitry 8 operates to estimate the linewidth adjustment value by interpolation using linewidth adjustment values ​​from the linewidth correction data corresponding to the nearest larger linewidth and the nearest smaller linewidth.

[0090] In one embodiment, the line characteristics further include a proximity index, which is a parameter representing the average percentage of exposed or unexposed area around the line. The line width correction data is further associated with the proximity index.

[0091] In another embodiment, the proximity measure is a linear density classification having at least two classes.

[0092] In yet another embodiment, the proximity index is a line density index, and the processing circuitry is operative to estimate the line width adjustment value by interpolation using width adjustment values ​​from the line width correction data corresponding to the nearest larger line density index and the nearest smaller line density index.

[0093] In Fig. 15A the device 80 for processing print data defining the printed pattern is shown as a separate unit in communication with the system 70 for obtaining the compensation pattern. However, as shown diagrammatically in Fig. 15B the device 80 for processing print data defining the printed pattern may also be provided as part of and / or integrated in the system 70 for obtaining the compensation pattern. Preferably the processing circuit 8 forms part of the processing device 6.

[0094] Fig. 16 shows a schematic representation of an embodiment of a printing apparatus 1. The printing apparatus 1 comprises a device 9 for processing line width corrected print data obtained by a device 80 for processing print data according to the idea presented above. The printing apparatus 1 is a printing apparatus of a system 70 for obtaining a correction pattern for a workpiece patterning device. The printing apparatus 1 comprises a print head 32 having at least one exposure beam sweepable in a sweep direction. The printing apparatus 1 further comprises a control unit 5. The control unit 5 is arranged to control the operation and relative movement of the print head based on the line width corrected print data.

[0095] In Figure 14 the control unit 5 and the device for processing edge correction print data 9 are shown as separate units. However, they may be integrated into a common unit. Also, the processing circuitry of the device for processing print data 80 may be integrated into the same unit as the control unit 5 and / or the device for processing edge correction print data 9. Also, the processing device 6 may be part of the common unit.

[0096] The above-described embodiments should be understood as some illustrative examples of the present invention. It is 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, where technically possible. However, the scope of the present invention is defined by the appended claims.

[0097]

number

Claims

1. 1. A method for obtaining line width correction data for a workpiece patterning device, comprising: A step (S2) of printing a calibration pattern using an exposure beam (32) sweepable in a sweep direction (Y), The printing (S2) is performed in accordance with calibration pattern printing data; the calibration pattern having a plurality of exposed and unexposed lines extending in the sweep direction (Y) and having different line widths and different distances to adjacent lines; measuring (S4) the line widths of the lines in a scanning direction (X) perpendicular to the sweep direction (Y) of the printed calibration pattern; - calculating (S6) a deviation of the measured line width of the line from an intended line width of the line according to print data of the calibration pattern; A step (S8) of calculating line width correction data (123, 126) based on the calculated deviation for adapting a line width of the pattern printing data before printing to compensate for the calculated deviation, the line width correction data (123, 126) being associated with at least an intended line width and whether the line is an exposed or unexposed line; A method for providing the above.

2. determining a proximity metric for each of the lines of the calibration pattern (S7), the proximity metric is a parameter representing the ratio between the distance (119) to the closest line and the line width (114), The method of claim 1 , wherein the linewidth correction data is further associated with the proximity indicator.

3. A method for obtaining line width correction print data, comprising: A step (S10) of obtaining print data of a pattern to be printed; A step (S12) of identifying a line in a sweep direction (Y) of the pattern to be printed; - determining line characteristics of said line (S14), said line characteristics including at least a line width and information whether said line is an unexposed line (116; 116B) or an exposed line (110; 110B); a step (S16) of estimating a line width adjustment value for each of the identified lines based on the determined line width and on information as to whether the line is an unexposed line (116, 116B) or an exposed line (110; 110B) from line width correction data (123, 126) obtained by the method according to claim 1; adapting the print data defining the identified lines to line width corrected print data in accordance with the line width adjustment values ​​(S18); A method for providing the above.

4. said adapting (S18) of said print data is performed in a bitmap domain; 4. The method of claim 3, wherein the intensities of individual bits (90) at or adjacent to each of the line ends (84) to be adjusted are adjusted to achieve a sum of each of the line end position adjustment values ​​equal to an amount of the estimated line width adjustment value.

5. 5. The method of claim 3 or 4, characterized in that the estimation (S16) of the linewidth adjustment value comprises an interpolation using linewidth adjustment values ​​from the linewidth correction data corresponding to a nearest larger linewidth and a nearest smaller linewidth.

6. The line characteristic further comprises a proximity indicator; said proximity metric being a parameter expressing the ratio between the distance (119) to the nearest neighboring line and the line width (114); The method according to any one of claims 3 to 5, characterized in that the line width correction data is further associated with the proximity measure.

7. A method for printing a pattern, comprising the steps of: A step (S20) of acquiring line width correction print data of the pattern to be printed, the line width correction print data being acquired by the method according to claim 3; Controlling (S22) a printing process of a workpiece (20) at least a portion of which is coated with a layer sensitive to electromagnetic or electron radiation based on the line width correction print data; A method for providing the above.

8. 8. The method of claim 7, wherein the step (S22) of controlling the printing process comprises controlling simultaneously operating exposure beams (34) to provide micro-sweeps in the sweep direction (Y) during scanning in a scan direction (X) perpendicular to the sweep direction (Y) to create scan strips.

9. 9. The method of claim 8, wherein the step (S22) of controlling the printing process further comprises producing a plurality of the scanning strips offset in the sweep direction.

10. 1. A system (70) for acquiring line width correction data for a workpiece patterning device, comprising: A printing device (1) configured to create a calibration pattern using an exposure beam (32) that is sweepable in a sweep direction (Y), comprising: The printing device (1) is configured to perform the printing in accordance with calibration pattern printing data; a printing device (1), the calibration pattern having a plurality of exposed and unexposed lines extending in the sweep direction (Y) and having different line widths and different distances to adjacent lines; a measuring device (4) arranged to measure the line widths of the lines of the printed calibration pattern in a scanning direction (X) perpendicular to the sweep direction (Y); a processing device (6) configured to calculate a deviation of the measured line width of the line from an intended line width of the line according to print data of the calibration pattern, the processing device (6) is further configured to calculate, based on the calculated deviation, line width correction data (123, 126) for adapting a line width of pattern printing data before printing to compensate for the calculated deviation; a processing device (6), the line width correction data being associated with at least an intended line width and whether the line is an exposed or unexposed line; A system comprising:

11. The processing unit (6) is further configured to determine a proximity metric for each of the lines of the calibration pattern; the proximity metric being a parameter representative of the average percentage of exposed or unexposed area (118) around the line of the calibration pattern; The system of claim 10 , wherein the linewidth correction data is further associated with the proximity indicator.

12. An apparatus (80) for processing print data defining a pattern to be printed, comprising: A processing circuit (8); A memory (7), The memory (7) includes instructions executable by the processing circuitry (8), whereby the processing circuitry (8) Obtain print data for the pattern to be printed; Identifying the lines (110, 110B; 116, 116B) of the sweep direction of the pattern to be printed; determining line characteristics of said lines (110, 110B; 116, 116B), said line characteristics including at least a line width and whether said lines are unexposed lines (116; 116B) or exposed lines (110; 110B); estimating a line width adjustment value for each of the identified lines based on the determined line width and on information whether the line is an unexposed line (116, 116B) or an exposed line (110; 110B) from line width correction data (123, 126) obtained by the method according to claim 1, a memory (7) operative to adapt the print data defining the identified lines to line width corrected print data in accordance with the line width adjustment value; An apparatus comprising:

13. 13. The apparatus of claim 12, wherein the processing circuitry (8) operates to adapt the print data in a bitmap domain, and the intensities of individual bits (90) at or adjacent to each line end (84) to be adjusted are adjusted to achieve a sum of each line end position adjustment value equal to the amount of the estimated line width adjustment value.

14. 14. Apparatus according to claim 12 or 13, characterized in that the processing circuitry (8) is operative to estimate linewidth adjustment values ​​by interpolation using linewidth adjustment values ​​from the linewidth correction data corresponding to a nearest larger linewidth and a nearest smaller linewidth.

15. A printing device (1), comprising: A device (6) for processing line width correction print data obtained by the device for processing print data according to claim 12, comprising: an apparatus (6), the printing apparatus (1) being a printing apparatus (1) of the system (70) for obtaining a compensation pattern for a workpiece patterning device according to claim 10; a print head (32) having an exposure beam (34) sweepable in a sweep direction (Y); A control unit (5), a control unit (5), the control unit (5) being arranged to control the operation and relative motion of the print head (32) based on the line width correction print data; A printing device comprising:

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