JP4432037B2 - Exposure system with data correction function - Google Patents

Description

  The present invention relates to an exposure apparatus with a correction function for mark position data, which is data indicating the position of a mark that defines the outline of a drawing area.

  In printing a circuit pattern on a printed circuit board by a photolithography technique, a pattern is drawn by an exposure device on a substrate on which a photoresist layer is formed. And after drawing a circuit pattern, a printed circuit board is obtained by performing various processes.

The circuit pattern needs to be drawn at a predetermined position on the printed circuit board, but the board may be slightly deformed by heat treatment after drawing, and the drawing position of the pattern deviates from the original position. There is a case. Therefore, for example, positioning marks are provided in advance at predetermined positions such as four corners on the substrate, and the position of the positioning marks due to deformation of the substrate is measured in advance to correct the displacement, thereby adjusting the pattern drawing position ( For example, see Patent Document 1).
JP 2000-122303 A (pages 5 to 6)

  When correcting the displacement of the position of the drawing area with respect to the substrate based on the displacement of the positioning mark on the substrate, the error that occurs in the stage of detecting the positioning mark is not corrected. Therefore, there is a possibility that the measurement error is included in the data indicating the actual position of the positioning mark, that is, the position after the deformation of the substrate, and in this case, accurate alignment correction is difficult.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an exposure apparatus that corrects errors in the positioning mark detection stage, thereby accurately correcting misalignment or the like of the drawing region and enabling alignment correction with high accuracy. .

  The exposure apparatus of the present invention draws an object to be drawn on which a plurality of marks that define the outline of the drawing area are corrected in order to correct a shift in the position of the drawing area that is an area for drawing a predetermined pattern. An exposure apparatus includes a mark position detection unit that detects actual positions of a plurality of marks, a mark position data generation unit that generates mark position data indicating the actual positions of the plurality of marks, and each of the plurality of mark position data. The data admissibility determining means for determining whether or not the non-permissible data exceeds a predetermined error allowable range, and a plurality of mark position data are correctable data that can be used for correcting the position of the drawing area. Data applicability determination means for determining whether or not the data is based on the number of non-permissible data, and data correction means for correcting the non-permissible data into correction mark position data. When the data applicability determining means determines that the mark position data is modifiable data, the data correcting means corrects the non-permissible data as necessary to obtain corrected mark position data, and the exposure apparatus The drawing object is drawn by correcting the position of the drawing area based on the position data and the correction mark position data.

  The exposure apparatus of the present invention corrects the drawing area based on mark position data indicating the actual position of a plurality of marks that define the outline of the drawing area, that is, the position of the mark after deformation of the drawing object. Not only the displacement of the drawing area but also the shape change of the drawing area itself can be corrected.

  The drawing area is rectangular, for example, and in this case, four marks are located at the vertices of the drawing area. Then, the data admissibility determining means determines that the first mark position data is non-permissible data based on an error in distance between the first mark indicated by the first mark position data and a mark other than the first mark. It is preferable to determine whether there is any mark position data and to determine all the mark position data in the same manner as the first mark position data.

  The data admissibility determination means includes a first distance error that is a distance between the first mark and the second mark closest to the first mark, and the first mark next to the first mark and the second mark. Whether the first mark position data is non-permissible data based on whether the sum of errors of the second distance, which is the distance to the third mark close to the first mark, is within a predetermined permissible range. It is desirable to determine whether or not. Further, the data admissibility determining means adds an error of the third distance, which is the distance between the second mark and the third mark, to the sum of the errors of the first distance and the second distance. It is more desirable to determine whether or not the first mark position data is non-permissible data based on the sum of the above.

  For example, when the number of non-permissible data is 1 or less, the data applicability determination unit determines that the mark position data is applicable data. When there is one non-permissible data, the correction mark position data is indicated by the data correction unit at a position where a parallelogram is formed together with the first to third marks indicated by the mark position data excluding the non-permissible data. If there is no non-permissible data by correcting the non-permissible data so that there is a mark and there is no non-permissible data, it is preferable that the data correction unit does not correct the mark position data.

  For example, when the number of non-permissible data is 2 or more, the data applicability determination unit determines that the mark position data is not applicable data.

  The exposure apparatus preferably further includes warning means for warning the user that a plurality of mark position data is not applicable data when the data applicability determination means determines that the mark position data is not applicable data.

  For example, the data admissibility determining means determines whether the first mark position data is based on the error in the distance between the first mark indicated by the first mark position data and the other marks of the first mark and the positional relationship. It is determined whether the data is non-permissible data, and all the mark position data are determined in the same manner as the first mark position data. In this case, the data admissibility determining means determines whether or not the first mark position data is non-permissible data based on the sum of errors in the distance between the first mark and the plurality of other marks. It is preferable to do.

  According to the mark position data correction method of the present invention, in order to correct a displacement between a position and a shape of a drawing area which is an area for drawing a predetermined pattern, a plurality of drawing area contours expressed on the surface of the drawing object are defined. This is a method of correcting mark position data indicating the position of the mark. In the mark position data correction method, the mark position detection unit detects the actual positions of the plurality of marks, the mark position data generation unit generates mark position data indicating the actual positions of the plurality of marks, The data admissibility determining means determines whether each of the plurality of mark position data is non-permissible data exceeding a predetermined error allowable range, and the data applicability determining means determines that the plurality of mark position data is a drawing area. It is determined based on the number of non-permissible data whether or not the data is applicable data that can be used to correct the position and shape. Further, when the data applicability determining unit determines that the mark position data is applicable data, the data correcting unit corrects the non-permissible data to obtain corrected mark position data.

  According to the present invention, it is possible to realize an exposure apparatus capable of accurately correcting misalignment and deformation of a drawing area and correcting alignment with high accuracy by correcting an error that occurs in a positioning mark detection stage.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an exposure apparatus of this embodiment. FIG. 2 is a perspective view showing a substrate installed in the exposure apparatus.

  The exposure apparatus 10 includes a base 11 and a fixed table 29. A drawing table 18 for fixing the substrate 20 is disposed on the base 11. The fixed table 29 is provided with an exposure laser oscillator 25 and an exposure optical system for guiding the exposure laser light LP from the exposure laser oscillator 25 to the drawing table 18. A pair of parallel rails 12 are arranged on the upper surface of the base 11, and the drawing table 18 can be moved on the rails 12 by a drive unit 13 having a motor. In the following, the main scanning direction perpendicular to the moving direction of the drawing table 18 is defined as the Y direction, and the sub-scanning direction parallel to the moving direction of the drawing table 18 is defined as the X direction. A drawing coordinate system with the point O as the origin is defined.

  A measuring camera 56 is provided on the base 11 outside the rail 12. The measurement camera 56 has a telescopic arm portion 60, and first to first provided at the end portion of the substrate 20 by moving an imaging portion 62 including an imaging element (not shown) in the main scanning direction. All the fourth alignment holes H0 to H3 can be photographed. The first to fourth alignment holes H <b> 0 to H <b> 3 are formed by a positional shift and a shape change of a drawing region that is a region for drawing a circuit pattern on the exposure surface E of the substrate 20 caused by deformation of the substrate 20 due to heat treatment or the like. In order to correct, it is provided at the four corners of the drawing area. Here, the first to fourth alignment holes H0 to H3 are provided so as to be positioned at the vertices of the rectangular drawing region, and the deformation amount of the substrate 20 is small, so that the actual, that is, the substrate 20 The region defined by the centers of the first to fourth alignment holes H0 to H3 after deformation is also substantially rectangular.

  When the substrate 20 is fixed on the drawing table 18, the drawing table 18 reciprocates on the rail 12 along the sub-scanning direction (X direction). Then, while the drawing table 18 reciprocates, the measurement camera 56 moves along the main scanning direction (Y direction) and photographs the first to fourth alignment holes H0 to H3. Thereby, the positions of the first to fourth alignment holes H0 to H3 on the exposure surface of the substrate 20 are measured. Then, as will be described later, it is determined whether or not the mark position data indicating the center positions of the first to fourth alignment holes H0 to H3 can be applied to the correction of the drawing region, and it is determined that the mark position data can be applied. If so, the process proceeds to the exposure process.

  In the exposure process, first, the drawing table 18 moves again on the rail 12 toward the fixed table 29 side, and the exposure laser beam LP is irradiated toward the substrate 20 as described below. The exposure laser light LP oscillated from the laser oscillator 25 is deflected by the first beam bender 26 and guided to an optical modulation unit 28 constituted by an acousto-optic element (AOM). After being modulated by the light modulation unit 28, the exposure laser light LP is guided to the polygon mirror 36 via the second beam vendor 30, the lens 32, and the third beam vendor 34. The exposure laser light LP is deflected by the reflection surface of the polygon mirror 36 and reaches the f-θ lens 38. At this time, the polygon mirror 36 deflects the exposure laser beam LP along the main scanning direction (Y direction). The exposure laser light LP that has passed through the f-θ lens 38 is guided to the drawing table 18 via the turning mirror 40 and the condenser lens 42. As a result, the exposure laser beam LP is irradiated onto the substrate 20, and the drawing area of the exposure surface E is exposed according to a predetermined circuit pattern.

  FIG. 3 is a schematic block diagram of the exposure apparatus in the present embodiment.

  The main body control unit 50 is a device that controls the entire exposure apparatus 10, and an exposure control unit 53 is provided in the main body control unit 50. The exposure control unit 53 sends control signals to the table driving unit 13, the measurement camera control unit 52, the light modulation unit driving unit 55, the polygon mirror driving unit 57, and the like.

  The measurement camera 56 sequentially photographs the first to fourth alignment holes H0 to H3 based on the control of the measurement camera control unit 52 based on the control signal from the exposure control unit 53. During this time, the table driving unit 13 controls the movement of the drawing table 18 to which the substrate 20 is fixed, based on the control signal transmitted from the exposure control unit 53. The imaging results of the first to fourth alignment holes H0 to H3 are sent to the data processing unit 54. The data processing unit 54 changes the first to first data in the drawing coordinate system from the coordinate system in the imaging range of the measurement camera 56. The coordinates of the center of the four alignment holes H0 to H3 are calculated, and each coordinate data is set as mark position data.

  The data processing unit 54 sends the mark position data to the data determination unit 59. In the data determination unit 59, whether or not the mark position data can be used for correcting the drawing area, that is, the positions of the first to fourth alignment holes H0 to H3 indicated by the mark position data are the drawing area to be originally drawn. It is determined whether or not an error larger than the vertex is included. If the data determination unit 59 determines that the mark position data has a large error and cannot be applied to the correction of the drawing area, it notifies the abnormality that the circuit pattern cannot be accurately drawn on the substrate 20 and the substrate 20 needs to be replaced. In order to warn the user that this is the case, the data determination unit 59 turns on a warning lamp 58 provided on the surface of the exposure apparatus 10.

  On the other hand, when the data determination unit 59 determines that the mark position data can be applied to the correction of the drawing area, a signal notifying that the mark position data is applicable is transmitted to the data processing unit 54. As will be described later, the data processing unit 54 sends mark position data corrected as necessary to the exposure control unit 53, and the exposure process starts. In the exposure process, first, the data processing unit 54 sends a control signal for performing exposure for forming a circuit pattern based on the mark position data corrected as necessary to the exposure control unit 53. The exposure control unit 53 controls the table driving unit 13, the light modulation unit driving unit 55, and the polygon mirror driving unit 57, so that the substrate 20 moves on the drawing table 18 in the sub-scanning direction (X direction). The exposure surface E is exposed to form a circuit pattern.

  FIG. 4 is a diagram schematically showing a method for determining whether or not an error in mark position data indicating an alignment hole is within an allowable range. FIG. 5 is a diagram showing a mark based on the corrected mark position data. FIG. 6 is a diagram showing a drawing area corrected based on the mark position data.

  Whether or not the error of the mark position data, which is the coordinate data indicating the positions of the first to fourth alignment holes H0 to H3, is within the allowable range, is determined by the data determination unit 59 based on the distance between the alignment holes. It is judged as follows. Regarding the second mark position data indicating the position of the second alignment hole H1, L01, which is the actual distance between the first alignment hole H0 and the second alignment hole H1, and the second alignment hole H1 and the third alignment hole H2 The actual distance L12 and the actual distance L02 between the first alignment hole H0 and the third alignment hole H2 are calculated (see FIG. 4A). Here, the actual distance refers to a distance based on mark position data indicating the positions of the first to fourth alignment holes H0 to H3 calculated based on the measurement by the measurement camera 56.

Subsequently, the distance W01 between the first alignment hole H0 and the second alignment hole H1, and the distance W12 between the second alignment hole H1 and the third alignment hole H2 in the drawing data which is data indicating the drawing area to be originally drawn, The distance W02 between the first alignment hole H0 and the third alignment hole H2 is calculated. Differences between W01, W12, and W02, which are the distances between the alignment holes on the drawing data calculated in this way, and L01, L12, and L02, which are actual distances between the corresponding alignment holes, are used as errors. A total error D012, which is the sum of absolute values, is calculated as shown in equation (1).

D012 = ABS (W01-L01) + ABS (W12-L12) + ABS (W02-L02) (1)

The total error D012 is taken as the error of the second mark position data. For the total error D012, a permissible amount CL2 is determined in advance based on the alignment hole machining accuracy and the like, and the data determination unit 59 compares the total error D012 and the permissible amount CL2 to determine the total error. When D012 is larger than the allowable amount CL2, it is determined that the second mark position data cannot be used for correcting the drawing area as it is, and is non-permissible data that needs to be corrected.

  Similarly, the data determination unit 59 also determines whether the first, third, and fourth mark position data indicating the positions of the first, third, and fourth alignment holes H0, H2, and H3 are non-permissible data. (See FIGS. 4B to 4D). Thus, the reliability of the mark position data indicating the alignment hole is such that the distance between two other alignment holes with a short distance, that is, two alignment holes excluding those on the diagonal line of the substantially rectangular drawing region, This is determined based on the distance between the two alignment holes.

  When it is determined whether or not all the first to fourth mark position data are non-permissible data, the data determination unit 59 determines the first to fourth mark position data based on the number of non-permissible data. It is determined whether it can be applied to the correction of the position and shape of the drawing area. That is, when no non-permissible data is included or when one non-permissible data is included, it is determined that the first to fourth mark position data can be applied to the correction of the drawing area. On the other hand, when there are two or more non-permissible data, it is considered that the measurement error of the first to fourth alignment holes H0 to H3 by the measurement camera 56 and the deformation of the substrate 20 are remarkably large, and the non-permissible data is trusted. Since it is impossible to appropriately correct the highly-corrected correction mark position data, it is determined that such mark position data cannot be applied to the correction of the drawing area.

  When the first to fourth mark position data includes one non-permissible data, the non-permissible data is corrected as follows (see FIG. 5). That is, when the total error D103 of the first mark position data indicating the position of the first alignment hole H0 is larger than the allowable amount CL0 and only the first mark position data is non-permissible data, the first mark position data is Correction mark position data is corrected to indicate a position H0 ′ that forms a parallelogram with the three points of the second to fourth alignment holes H1 to H3. The correction of the mark position data is performed by the data processing unit 54 in accordance with an instruction signal from the data determining unit 59.

When the data determination unit 59 determines that the first to fourth mark position data is applicable data that can be applied to the correction of the drawing area, and the non-permissible data is not included, the data processing unit 54 When the drawing area is corrected based on the first to fourth mark position data and one non-permissible data is included, the data processing unit 54 corrects the drawing area based on the mark position data including the correction mark position data. (See FIG. 6). In the correction of the drawing area by the data processing unit 54, first, the first to first midpoints of the four sides of the actual drawing area that is a rectangle close to the rectangle with the first to fourth alignment holes H0 to H3 as vertices. Fourth middle points M01, M12, M23, and M30 are calculated. The region indicated by the broken line, which is composed of a line segment LX connecting the first midpoint M01 and the third midpoint M23, and a line segment LY connecting the second midpoint M12 and the fourth midpoint M30, is a parallelogram. The shape of the drawing area in the drawing data is corrected so that the shape becomes. With this correction process, the position of the drawing area in the drawing data is also set to X ₀ to ₃ that is the X coordinate value of the first to fourth alignment holes H0 to H3 and Y ₀ to Y value of the Y coordinate. The coordinates of the center point C of the actual drawing area calculated from the average of ₃ ((X ₀ + X ₁ + X ₂ + X ₃ ) / 4, (Y ₀ + Y ₁ + Y ₂ + Y ₃ ) / 4) Modified to move.

  FIG. 7 is a flowchart showing a drawing data correction routine performed in the main body control unit 50.

  The drawing data correction routine is started by fixing the substrate 20 provided with the first to fourth alignment holes H0 to H3 onto the drawing table 18. In step S701, the measurement camera 56 photographs the first to fourth alignment holes H0 to H3, measures the position, and proceeds to step S702. In step S702, the data processing unit 54 generates first to fourth mark position data indicating the positions of the first to fourth alignment holes H0 to H3 in the drawing coordinate system from the photographing result of the measurement camera 56, and step The process proceeds to S703. In step S703, the data determination unit 59 determines whether correction is necessary for the first to fourth mark position data. If any of the first to fourth mark position data is determined to be non-permissible data that needs to be corrected, the process proceeds to step S704, and the first to fourth mark position data does not include non-permissible data correction. If it is determined that no correction is necessary, the process proceeds to step S707.

  In step S704, the data determination unit 59 determines whether the first to fourth mark position data can be used for correcting the drawing area, that is, whether there is one non-permissible data or two or more. to decide. When there is one non-permissible data, it is determined that the mark position data including the correction mark position data can be applied to the correction of the drawing area by correcting the non-permissible data to the correction mark position data. The process proceeds to step S705. If there are two or more non-permitted data, it is determined that the mark position data cannot be applied to the correction of the drawing area, and the process proceeds to step S706.

  In step S705, the data processing unit 54 corrects the non-permissible data to obtain correction mark position data, and the process proceeds to step S707. In step S706, the warning lamp 58 is lit to notify the user that the drawing area cannot be corrected based on the mark position data and the circuit pattern cannot be accurately drawn on the substrate 20. In step S707, the data processing unit 54 corrects the position and shape of the drawing area on the drawing data based on the mark position data including the correction mark position data as necessary, and the drawing data correction routine ends.

  As described above, according to the present embodiment, the mark position data indicating the positions of the first to fourth alignment holes H0 to H3 measured by the measurement camera 56 is used to correct the position and shape deviation of the drawing area. Whether or not it can be applied is determined, and the drawing area is corrected only when it can be applied. Therefore, even when a measurement error is large, accurate alignment correction is possible.

  The shape of the drawing area is not limited to this embodiment, and the number of alignment holes can be adjusted according to the shape of the drawing area. For example, if the drawing area is a triangle or a polygon, the number of alignment holes of this embodiment is increased or decreased so as to be arranged at each vertex, and a plurality of mark position data can be applied to the correction of the drawing area accordingly. The upper limit of the number of unacceptable data to be determined may be increased or decreased. In addition, when a plurality of drawing areas are included on the same substrate, by providing a plurality of alignment holes for each drawing area, it is possible to perform highly accurate alignment correction as in the present embodiment.

  The method for correcting the drawing area on the drawing data based on the mark position data is not limited to the present embodiment, and may be corrected in the exposure process, not in the data processing.

  The necessity of correcting the mark position data is not limited to the distance between the alignment holes, but may be determined based on the positional relationship between the alignment holes. For example, the mark position data indicating the position of a certain mark may be determined based on an angle formed by a line segment connecting the other two marks. When determining based on the distance between the alignment holes, the necessity of correction is determined based only on the total distance between the mark indicated by the mark position data to be determined and the two shortest marks. May be.

It is a perspective view which shows exposure apparatus. It is a perspective view which shows the board | substrate installed in the exposure apparatus. It is a schematic block diagram of an exposure apparatus. It is a figure which shows roughly the method of determining whether the error of the mark position data which shows an alignment hole is within tolerance. It is a figure which shows the mark based on the corrected mark position data. It is a figure which shows the drawing area | region corrected based on mark position data. It is a flowchart which shows the drawing data correction routine in a main body control part.

Explanation of symbols

10 exposure apparatus 20 substrate (object to be drawn)
50 Main body control unit 53 Exposure control unit 54 Data processing unit (mark position data generation means / data correction means)
56 Measurement camera (mark position detection means)
58 Warning lamp (Warning means)
59 Data judging section (data admissibility judging means / data applicability judging means)
E Exposure surface (surface)
H0 to H3 1st to 4th alignment holes (marks)

Claims (11)

An exposure apparatus for drawing an object to be drawn in which four marks defining the outline of the drawing area are represented on the surface in order to correct a deviation in the position and shape of the drawing area that is an area for drawing a predetermined pattern. ,
Mark position detecting means for detecting actual positions of the four marks;
Mark position data generating means for generating mark position data respectively indicating the actual positions of the four marks;
Data admissibility determining means for determining whether each of the four mark position data is non-permissible data exceeding a predetermined error allowable range;
Data applicability determining means for determining whether or not the four mark position data are correctable data that can be used for correcting the position and shape of the drawing area, based on the number of non-permissible data;
Data correction means for correcting the non-permissible data to be correction mark position data,
The data applicability determining means determines that the mark position data is the applicable data when the number of non-permissible data is one or less;
When there is one non-permissible data, the correction mark position data at a position where the data correction unit forms a parallelogram together with the first to third marks indicated by the mark position data excluding the non-permissible data. The correction mark position data is corrected by correcting the non-permissible data so that there is a mark indicated by: and the position and shape of the drawing area are corrected based on the mark position data and the correction mark position data. Draw the body ,
When there is no non-permissible data, the data correction unit does not correct the mark position data, but draws the drawing object by correcting the position and shape of the drawing area based on the mark position data. An exposure apparatus. The drawing area is a rectangular shape, the exposure apparatus according to claim 1, before Symbol marks, characterized in that located at the apex of the drawing area. The data admissibility determining means determines that the first mark position data is not based on an error in distance between the first mark indicated by the first mark position data and the mark other than the first mark. 2. The exposure apparatus according to claim 1 , wherein it is determined whether the data is permissible data, and all the mark position data are determined in the same manner as the first mark position data. The data admissibility determining means includes a first distance error which is a distance between a first mark indicated by first mark position data and a second mark closest to the first mark, and the first mark Based on whether or not the sum of errors in the second distance, which is the distance between the mark and the third mark next to the first mark next to the second mark, is within a predetermined tolerance range, according to claim 1, wherein the first mark position data said it is determined whether the non-allowed data, determines as in the first mark position data for all of the mark position data Exposure equipment.   The data admissibility determination means further adds a third distance error, which is a distance between the second mark and the third mark, to a sum of errors between the first distance and the second distance. 5. The exposure apparatus according to claim 4, wherein it is determined whether or not the first mark position data is the non-permissible data based on a total of added errors. The data applicability determining means, said exposure according to any one of claims 1 to 5 the number of non-allowed data is the mark position data in the case of two or more, characterized in that determining that the non-applicable data apparatus. When the data applicability determination unit determines that the mark position data is not the applicable data, the data applicability determination unit further includes warning means for warning the user that the four mark position data are not the applicable data. an apparatus according to any one of claims 1 to 6, wherein.   Based on the positional relationship between the first mark indicated by the first mark position data and the other marks of the first mark, the data admissibility determination means determines that the first mark position data is non-permissible data. The exposure apparatus according to claim 1, wherein all the mark position data are determined in the same manner as the first mark position data. The data admissibility determining means determines whether the first mark position data is non-permissible data based on an error in the distance between the first mark and the other mark. An exposure apparatus according to claim 8 . The data admissibility determining unit determines whether or not the first mark position data is non-permissible data based on a total distance error between the first mark and the plurality of other marks. An exposure apparatus according to claim 9 . Mark positions indicating the positions of four marks that define the outline of the drawing area, which are represented on the surface of the drawing object, in order to correct the deviation of the position and shape of the drawing area, which is an area for drawing a predetermined pattern A mark position data correction method for correcting data,
Mark position detection means detects the actual position of the four marks,
Mark position data generating means generates mark position data indicating the actual positions of the four marks,
A data admissibility determining means determines whether each of the four mark position data is non-allowable data exceeding a predetermined error allowable range,
A data applicability determining means determines whether or not the four mark position data are applicable data that can be used to correct the position and shape of the drawing area based on the number of the non-permissible data;
The data applicability determining means determines that the mark position data is the applicable data when the number of non-permissible data is one or less;
When there is one non-permissible data, the data correction unit that corrects the non-permissible data to obtain correction mark position data includes first to third marks indicated by the mark position data excluding the non-permissible data. And the correction mark position data by correcting the non-permissible data so that there is a mark indicated by the correction mark position data at the position where the parallelogram is formed,
A mark position data correction method , wherein the data correction means does not correct the mark position data when there is no non-permissible data .

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