JP2016178231A - Charged particle beam lithography apparatus, and beam resolution measuring method for charged particle beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charged particle beam lithography apparatus and beam resolution measuring method, that are capable of quickly and accurately measuring beam resolution without requiring to install, on a stage, a rotation mechanism for rotating a mark substrate.SOLUTION: A charged particle beam lithography apparatus 100 irradiates a sample on a stage 105 with a charged particle beam to draw a pattern. The charged particle beam lithography apparatus 100 comprises: a mark substrate 10 which is provided on the stage 105 and on which a plurality of mark patterns having different rotation angles are formed; and a detector 209 for detecting charged particles reflected from the mark substrate 10. Each of the plurality of mark patterns includes a linear part and another linear part orthogonal to the linear part. Beam resolution is calculated by calculating a waveform width of a scan waveform in scanning a linear part of each mark pattern by using the charged particle beam, and selecting a mark pattern having a minimum waveform width.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a charged particle beam drawing apparatus and a beam resolution measuring method of a charged particle beam.

  As LSIs are highly integrated, circuit line widths required for semiconductor devices have been reduced year by year. In order to form a desired circuit pattern on a semiconductor device, a reduction projection type exposure apparatus is used to form a high-precision original pattern pattern formed on quartz (a mask, or a pattern used particularly in a stepper or scanner is also called a reticle). )) Is reduced and transferred onto the wafer. A high-precision original pattern is drawn by an electron beam drawing apparatus, and so-called electron beam lithography technology is used.

  In an electron beam lithography system, an electron beam is scanned on a mark substrate (calibration substrate) on which a through hole or mark is formed, and a current value of the electron beam that has passed through the through hole or a reflected electron from the mark is detected. And the beam resolution was measured. Since the moving direction of the stage on which the mark substrate is placed is aligned with the scanning direction of the electron beam, the measurement accuracy of the beam resolution depends on the mounting accuracy of the mark substrate. For example, when the line-shaped mark and the scanning direction of the electron beam are not orthogonal, accurate beam resolution cannot be measured.

  For this reason, for example, in Patent Document 1, the electron beam is scanned while rotating the mark substrate little by little by a rotating mechanism to measure the beam resolution, and the mark substrate is rotated so that the beam resolution is minimized.

  However, it is difficult to provide an installation space for a rotation mechanism for rotating the mark substrate on the stage in the drawing apparatus. In addition, it has been difficult to produce a rotating mechanism without using a metal that is a source of magnetic field.

  Further, as in Patent Document 1, the method of repeating the rotation of the mark substrate and the scanning of the electron beam has a problem that it takes time to detect the rotation angle of the mark substrate that minimizes the beam resolution. Also, even if the rotation angle of the mark substrate that minimizes the beam resolution is detected, it is difficult to match the detected rotation angle depending on the reproducibility of the rotation mechanism, and it is confirmed whether the beam resolution is actually minimized. There was no way to do it.

JP 11-31655 A

  The present invention has been made in view of the above-described conventional situation, and there is no need to install a rotating mechanism for rotating the mark substrate on the stage, and a charged particle beam drawing apparatus and a charged particle beam measuring apparatus capable of quickly measuring accurate beam resolution. It is an object of the present invention to provide a beam resolution measuring method of a particle beam.

  A charged particle beam drawing apparatus according to an aspect of the present invention is a charged particle beam drawing apparatus that draws a pattern by irradiating a sample on a stage with a charged particle beam, and is provided on the stage and has different rotation angles. A mark substrate on which a plurality of patterns are formed, and a detector that detects charged particles reflected from the mark substrate.

  In the charged particle beam drawing apparatus according to an aspect of the present invention, each of the plurality of mark patterns has a rectangular portion, and the sides of the rectangular portion of each mark pattern are non-parallel.

  A charged particle beam drawing apparatus according to an aspect of the present invention uses a detection result of the detector to calculate a waveform width of a scan waveform when a rectangular portion of each mark pattern is scanned with a charged particle beam; and And a selection unit that selects a mark pattern having the minimum waveform width.

  The charged particle beam drawing apparatus according to one aspect of the present invention uses the detection result of the detector to scan the rectangular part of any one of the mark patterns while changing the direction with the charged particle beam, and the waveform width of the scan waveform And a selection unit that selects a mark pattern based on a waveform width for each scanning direction and a rotation angle of the scanned mark pattern.

  According to one aspect of the present invention, there is provided a charged particle beam beam resolution measuring method comprising: scanning a plurality of mark patterns formed on a mark substrate with different rotation angles with a charged particle beam; and charged particles reflected from the mark substrate. A step of detecting with a detector, a step of calculating a waveform width of a scan waveform when each mark pattern is scanned with a charged particle beam, using the detection result of the detector, and a mark with a minimum calculated waveform width A step of selecting a pattern, and a step of scanning the selected mark pattern with a charged particle beam during actual drawing and obtaining a beam resolution from the waveform width of the scan waveform.

  According to the present invention, accurate beam resolution can be quickly measured without installing a rotating mechanism for rotating the mark substrate on the stage.

It is a schematic block diagram of the drawing apparatus in 1st Embodiment. It is a schematic block diagram of an aperture member. (A) is a longitudinal cross-sectional view of a mark board | substrate, (b) is a perspective view of a mark board | substrate. (A)-(e) is the schematic of the mark pattern provided in the mark board | substrate. (A) is a figure which shows the example of the beam scan of a mark pattern, (b) is a figure which shows the example of the scan waveform acquired by beam scan. (A)-(e) is a figure which shows the example of the beam scan of a mark pattern. (A)-(e) is a figure which shows the example of the scan waveform acquired by beam scanning. It is a flowchart explaining the mark pattern selection method in 1st Embodiment. It is a figure which shows the example of the beam scanning method of the mark pattern in 2nd Embodiment. It is a graph which shows the relationship between a scanning direction and the width | variety of a scanning waveform. It is a flowchart explaining the mark pattern selection method in 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, a configuration using an electron beam will be described as an example of a charged particle beam. However, the charged particle beam is not limited to an electron beam, and a beam using charged particles such as an ion beam. It doesn't matter.

[First Embodiment]
FIG. 1 is a schematic configuration diagram of a drawing apparatus according to the first embodiment of the present invention. As illustrated in FIG. 1, the drawing apparatus 100 includes a drawing unit 150 and a control unit 160. The drawing apparatus 100 is an example of a multi charged particle beam drawing apparatus. The drawing unit 150 includes an electron column 102 and a drawing chamber 103. An electron gun 201, an illumination lens 202, an aperture member 203, a blanking plate 204, a reduction lens 205, a limiting aperture member 206, an objective lens 207, a deflector 208, and a detector 209 are arranged in the electron column 102. Yes.

  An XY stage 105 is disposed in the drawing chamber 103. On the XY stage 105, a mark substrate 10 and a substrate (not shown) on which a pattern is drawn are placed. Examples of the substrate (sample) to be subjected to pattern drawing include a wafer on which a semiconductor device is manufactured and an exposure mask for transferring a pattern onto the wafer. The mask also includes mask blanks on which no pattern is formed yet. On the XY stage 105, a mirror 210 for measuring the position of the XY stage 105 is further arranged.

  The control unit 160 includes a control computer 110, a memory 112, a deflection control circuit 130, a stage position detector 139, and a storage device 140 such as a magnetic disk device. The control computer 110, the memory 112, the deflection control circuit 130, the stage position detector 139, and the storage device 140 are connected to each other via a bus (not shown). In the storage device 140 (storage unit), drawing data is input from the outside and stored.

  The control computer 110 includes a drawing data processing unit 50, a drawing control unit 52, a waveform width calculation unit 60, and a mark pattern selection unit 62. Each unit of the control computer 110 may be configured by hardware or software. The memory 112 stores data input to and output from the control computer 110 and data being calculated.

  FIG. 2 is a schematic configuration diagram of the aperture member 203. As shown in FIG. 2, the aperture member 203 has vertical (y direction) m rows × horizontal (x direction) n rows (m, n ≧ 2) holes (openings) 203a in a matrix with a predetermined arrangement pitch. Is formed. In FIG. 2, for example, holes 203a in 512 × 512 rows are formed in the vertical and horizontal directions (x and y directions). Each hole 203a is formed of a rectangle having the same size and shape. Each hole 203a may be circular with the same outer diameter. As a part of the electron beam 200 passes through each of the plurality of holes 203a, multi-beams 200a to 200e are formed.

  The holes 203a formed in the aperture member 203 may have a plurality of rows in the vertical and horizontal directions (x and y directions) and only one row in the other. Further, the arrangement method of the holes 203a is not limited to the arrangement in which the vertical and horizontal directions are arranged in a lattice pattern as shown in FIG. 2, for example, the vertical (y direction) k-th row (k ≧ 1), The holes in the (k + 1) th row may be arranged so as to be shifted in the horizontal direction (x direction).

  In the blanking plate 204, through holes (openings) through which the multi-beams pass are opened at positions corresponding to the holes 203a of the aperture member 203 shown in FIG. Then, a set of two blanking deflection electrodes (blankers: blanking deflectors) is disposed across the corresponding passage hole in the vicinity of each passage hole. Further, a control circuit for applying a deflection voltage to one electrode of the blanker for each passage hole is disposed in the vicinity of each passage hole. The other of the two electrodes of the blanker is grounded.

  The electron beam passing through each through hole is deflected independently by a voltage applied to the electrode of the blanker. Blanking is controlled by this deflection. In this way, the plurality of blankers perform blanking deflection of the corresponding beams among the multi-beams that have passed through the plurality of holes 203a (openings) of the aperture member 203. In one shot, a plurality of shot patterns as many as the holes 203a are formed at a time.

  The drawing data processing unit 50 of the control computer 110 reads the drawing data from the storage device 140, performs a plurality of stages of data conversion processing, and generates shot data. Shot data is generated for each pixel, and the drawing time (irradiation time) of each beam is calculated.

  The drawing unit 150 performs drawing for the corresponding irradiation time for each shot of each beam. The electron beam 200 emitted from the electron gun 201 (emission part) illuminates the entire aperture member 203 almost vertically by the illumination lens 202. The electron beam 200 illuminates a region including all the holes 203 a of the aperture member 203. By passing the electron beam 200 through the hole 203a, for example, a plurality of rectangular electron beams (multi-beams) 200a to 200e are formed. The multi-beams 200a to 200e pass through the corresponding blankers of the blanking plate 204, respectively. Each blanker deflects individually passing electron beams (performs blanking deflection).

  The multi-beams 200 a to 200 e that have passed through the blanking plate 204 are reduced by the reduction lens 205 and travel toward a hole formed in the center of the limiting aperture member 206. Here, the position of the electron beam deflected by the blanker of the blanking plate 204 deviates from the center hole of the limiting aperture member 206 (blanking aperture member) and is blocked by the limiting aperture member 206. On the other hand, the electron beam that has not been deflected by the blanker of the blanking plate 204 passes through the hole at the center of the limiting aperture member 206. Blanking control is performed by ON / OFF of the individual blanking mechanism, and ON / OFF of the beam is controlled.

  As described above, the limiting aperture member 206 blocks each beam deflected so as to be in the beam OFF state by the individual blanking mechanism. A beam of one shot is formed by the beam that has passed through the limiting aperture member 206 formed from when the beam is turned on to when the beam is turned off.

  The multi-beams that have passed through the limiting aperture member 206 are focused by the objective lens 207 and become a pattern image with a desired reduction ratio. Are collectively deflected to irradiate the sample. For example, when the XY stage 105 is continuously moving, the beam irradiation position is controlled by the deflector 208 so as to follow the movement of the XY stage 105.

  The position of the XY stage 105 is measured by irradiating a laser from the stage position detector 139 toward the mirror 210 on the XY stage 105 and using the reflected light. The measured position of the XY stage 105 is output to the control computer 110. The drawing control unit 52 of the control computer 110 outputs the position information of the XY stage 105 to the deflection control circuit 130. The deflection control circuit 130 calculates deflection amount data for beam deflection so as to follow the movement of the XY stage 105 in accordance with the movement of the XY stage 105, and applies a deflection voltage to the deflector 208.

  The multi-beams irradiated at a time are ideally arranged at a pitch obtained by multiplying the arrangement pitch of the plurality of holes of the aperture member 203 by the desired reduction ratio described above. The drawing apparatus 100 performs a drawing operation by a raster scan method in which shot beams are continuously irradiated in order, and when drawing a desired pattern, a necessary beam is controlled to be beam ON by blanking control according to the pattern. The

  The drawing apparatus 100 periodically scans the beam on the mark substrate 10 placed on the stage in order to check the beam position and beam size and perform the beam evaluation. FIG. 3A is a conceptual diagram showing a longitudinal section of the mark substrate 10, and FIG. 3B is a perspective view of the mark substrate 10. 4A to 4E are diagrams showing examples of mark patterns provided on the mark substrate 10.

  The mark substrate 10 includes a silicon substrate 12 and a metal film 14 provided on the silicon substrate 12. The metal film 14 is a heavy metal thin film such as tantalum or tungsten. The metal film 14 constitutes a mark pattern 20.

  On the mark substrate 10, a cross-shaped mark pattern 20 composed of two orthogonal linear portions is formed. The mark pattern 20 includes a plurality of patterns having different rotation angles with respect to the X axis and Y axis of the mark substrate 10. For example, as shown in FIGS. 4A to 4E, a plurality of mark pattern groups having different rotation angles are formed on the mark substrate 10. Since the mark patterns 20a to 20e of the mark pattern groups (a) to (e) have different rotation angles, the linear portions are not parallel to each other (not parallel).

  A plurality of mark patterns having the same rotation angle are formed in each of the mark pattern groups because the mark patterns 20a to 20e are deteriorated by the electron beam irradiation, and the measurement reproducibility of the beam position and the accuracy of the resolution measurement are lowered. Because. When the mark patterns 20a to 20e are deteriorated, the undegraded mark patterns 20a to 20e that are not irradiated with the electron beam are selected and used.

  When the mark substrate 10 is scanned with an electron beam, reflected electrons reflected by the mark substrate 10 are detected by the detector 209. The detector 209 outputs a reflected electron signal indicating the intensity (amount) of the detected reflected electrons to the control computer 110. The waveform width calculator 60 calculates the width of the scan waveform from the reflected electron signal.

  For example, as shown in FIG. 5A, when the mark pattern 20 includes straight portions 21 and 22 that are orthogonal to each other, and the multi-beam B aligned in the y-axis direction is scanned with respect to the straight portion 21, the detection is performed. The reflected electron signal output from the device 209 has a waveform as shown in FIG. The waveform width calculation unit 60 calculates a waveform width W corresponding to the reflected electrons from the mark pattern 20 (straight line portion 21) from the reflected electron signal.

  The waveform width W varies depending on the angle formed by the longitudinal direction of the linear portion 21 and the scanning direction of the electron beam. When the longitudinal direction of the straight line portion 21 and the scanning direction of the electron beam are orthogonal, the waveform width W is minimized, and accurate information on the size of the electron beam and the like can be acquired from the waveform width W.

  The scanning direction of the electron beam and the moving direction of the XY stage 105 are matched. Due to the influence of the mounting accuracy of the mark substrate 10 on the XY stage 105, it is difficult to match the X and Y axes of the mark substrate 10 with the x and y directions of the electron beam scan. That is, when only the mark pattern 20 having the same rotation angle is formed on the mark substrate 10, it is difficult to make the longitudinal direction of the linear portion 21 or 22 orthogonal to the scanning direction of the electron beam.

  Therefore, in the present embodiment, a plurality of mark patterns 20 having different rotation angles are provided on the mark substrate 10, and an electron beam is scanned on each mark pattern 20 before actual drawing to calculate the waveform width W. The mark pattern 20 having the smallest waveform width W is regarded as having the most orthogonal (substantially orthogonal) relationship between the longitudinal direction of the straight line portion 21 or 22 and the scanning direction of the electron beam. Get information about the size, etc.

  For example, as shown in FIGS. 6A to 6E, when the multi-beams B arranged in the y direction are scanned in the x direction with respect to the mark patterns 20a to 20e, the reflected electron signal output from the detector 209 is The waveforms are as shown in FIGS. The waveform width calculation unit 60 calculates the waveform widths Wa to We of the scan waveforms of the mark patterns 20a to 20e. The mark pattern selection unit 62 selects a mark pattern having the smallest waveform width.

  For example, in the examples of FIGS. 7A to 7E, the waveform width Wb is the smallest, and the longitudinal direction of the straight line portion of the mark pattern Wb and the scanning direction of the electron beam are most orthogonal (substantially orthogonal). The mark pattern selection unit 62 selects the mark pattern Wb. By scanning the mark pattern Wb, highly accurate information on the resolution of the electron beam and the like can be acquired, and the size and irradiation position of the beam can be corrected with high accuracy based on the acquired information. By writing on the sample with the corrected electron beam, the pattern can be drawn with high accuracy.

  FIG. 8 is a flowchart for explaining a method of selecting a mark pattern 20 having an optimum rotation angle with respect to the scanning direction of the electron beam (a straight line portion is orthogonal to the scanning direction) from a plurality of mark patterns 20. .

  Of the plurality of mark patterns 20, the straight portion 21 or 22 of the mark pattern 20 that has not been scanned is scanned with an electron beam to obtain a reflected electron signal (scan waveform) (steps S101 and S102). A waveform width W is calculated from the acquired scan waveform (step S103).

  If there is a mark pattern 20 that has not been scanned (step S104_No), the process returns to step S101. When the mark patterns 20 of all the rotation angles are scanned (step S104_Yes), the mark pattern 20 having the smallest waveform width W among the calculated waveform widths W is selected (step S105).

  In this way, it is possible to select the mark pattern 20 having an optimal rotation angle with respect to the scanning direction of the electron beam. During the subsequent actual drawing, by using the selected mark pattern 20, it is possible to detect the resolution, size, blur, fluctuation, irradiation position, etc. of the electron beam with high accuracy.

  Thus, according to the present embodiment, a plurality of mark patterns 20 having different rotation angles are provided on the mark substrate 10, and the waveform width W of the scan waveform of each mark pattern 20 is optimal for the scan direction of the electron beam. A mark pattern 20 having a rotation angle can be selected. Since it is not necessary to rotate the mark substrate 10 itself, it is not necessary to provide a rotation mechanism for rotating the mark substrate 10 on the XY stage 105. In addition, accurate beam resolution can be quickly measured as compared with a method of repeatedly scanning an electron beam and rotating a mark substrate.

  In the flowchart shown in FIG. 8, the example in which the mark patterns 20 of all the rotation angles are scanned has been described. However, even if these mark patterns 20 are scanned from the rotation angles of the unscanned mark patterns 20, the waveform of the scan waveform If it is clear from experience that the width is not smaller than the calculated minimum value of the waveform width, the process may proceed to step S105 even if an unscanned mark pattern 20 remains.

  In the above-described embodiment, the example in which the multi-beams B aligned in the y direction are scanned in the x direction with respect to the linear portion 21 of the mark pattern 20 is described. You may scan.

[Second Embodiment]
In the first embodiment, a plurality of mark patterns 20 having different rotation angles are scanned, but the straight line portion 21 or 22 of one mark pattern 20 is scanned a plurality of times while changing the scanning direction (angle), The scan direction that minimizes the waveform width W may be obtained.

  For example, as shown in FIG. 9, the multi-beam B is scanned by switching the scanning direction from D1 to D5 with respect to the straight line portion 21 of one mark pattern 20. The waveform width calculator 60 calculates the waveform widths W1 to W5 of the scan waveform for each of the scan directions D1 to D5.

  As shown in FIG. 10, the mark pattern selection unit 62 plots the calculated waveform widths W1 to W5, performs curve fitting, and obtains the scan direction D0 in which the waveform width is minimized. The mark pattern selection unit 62 scans the mark pattern 20 having the optimum rotation angle, that is, the electron beam in the x direction or the y direction from the rotation angle of the scanned mark pattern 20 and the obtained scanning direction D0. The mark pattern 20 is selected in which the longitudinal direction of the straight line portion 21 or 22 is (substantially) orthogonal to the scanning direction.

  By scanning the mark pattern 20 selected by the mark pattern selection unit 62, the electron beam can be accurately evaluated.

  FIG. 11 is a flowchart for explaining the optimum mark pattern selection method in the present embodiment. Any one of a plurality of mark patterns 20 provided on the mark substrate 10 is set as a scan target.

  The straight line portion 21 or 22 of the mark pattern 20 is scanned with an electron beam to obtain a reflected electron signal (scan waveform) (steps S201 and S202). A waveform width W is calculated from the acquired scan waveform (step S203).

  If there is an unexecuted scan direction (step S204_No), the scan direction is changed (step S205), and the process returns to step S201. When the scanning of the electron beam is performed for all scanning directions (step S204_Yes), the calculated waveform width W is plotted in the order of the scanning direction (angle), and curve fitting is performed (step S206).

  Then, the scan direction (angle) at which the waveform width W is minimized is obtained, and from the rotation angle of the mark pattern 20 scanned in step S201 and the obtained scan direction, the plurality of mark patterns 20 on the mark substrate 10 are The mark pattern 20 with the optimum rotation angle is selected (step S207).

  As described above, according to the present embodiment, one mark pattern 20 is scanned in a plurality of scan directions, and the optimum is determined from the rotation angle of the scanned mark pattern 20 and the scan direction in which the waveform width of the scan waveform is minimized. It is possible to quickly select the mark pattern 20 having a proper rotation angle. By using the selected mark pattern 20, accurate beam evaluation can be performed during actual drawing.

  In the second embodiment, a plurality of calculated waveform widths are plotted and curve fitting is performed, and a scan direction in which the waveform width is minimized is obtained. However, curve fitting is not performed, and among the calculated plurality of waveform widths, The mark pattern 20 having the optimum rotation angle may be selected from the scan direction of the minimum waveform width and the rotation angle of the scanned mark pattern 20.

  In the first and second embodiments, the rotation angle of each mark pattern 20 and the number of rotation angles to be prepared are determined according to the mounting accuracy of the mark substrate 10 and the aperture size. preferable. For example, when the size of the entire beam group is 10 μm and the size of one beam is 10 nm, the mark rotation angle with respect to the scanning direction is 0.057 ° to place one beam on the end of the mark at a time. Need to be within. If eleven types of mark patterns are installed with a mark substrate mounting accuracy of ± 0.5 °, the rotation angle of the mark pattern is in increments of 0.1 °. As a result, the difference between the measured angle and the rotation angle of the mark pattern determined to be optimal falls within 0.05 °, so that the object can be achieved.

  The length from one end of the straight line portion 21 or 22 of the mark pattern 20 to the intersection (cross-shaped center) of the straight line portions 21 and 22 is preferably determined from the number and interval of electron beams to be scanned.

  Further, it is preferable to determine the length and width of the straight portions 21 and 22 and the rotation angle of each mark pattern 20 so that all the multi-beams to be scanned are simultaneously positioned on the straight portions 21 or 22.

  In the above-described embodiment, the cross-shaped mark pattern 20 in which the elongated rectangular linear portions 21 and 22 are orthogonal to each other is shown. However, the linear portion 21 and the linear portion 22 only need to form a right angle, and may be a T-shape or L-shape. It is good. The straight line portion 21 and the straight line portion 22 may not be connected and may be provided separately. The mark pattern 20 may consist of only one of the straight portions 21 and 22. The sides of the rectangular portions of the mark patterns 20 having different rotation angles are not parallel to each other.

  Although the multi-beam drawing apparatus is shown in the above embodiment, a single-beam drawing apparatus may be used. In this case, since the number of beams for scanning the mark pattern 20 is one, the mark pattern 20 does not have to be an elongated rectangular shape such as the straight portions 21 and 22, and may be a square shape, for example.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

DESCRIPTION OF SYMBOLS 10 Mark substrate 12 Silicon substrate 14 Metal film 20 Mark pattern 60 Waveform width calculation part 62 Mark pattern selection part 100 Drawing apparatus 110 Control computer 150 Drawing part 160 Control part 200 Electron beam 209 Detector

Claims (5)

A charged particle beam drawing apparatus for drawing a pattern by irradiating a sample on a stage with a charged particle beam,
A mark substrate provided on the stage and formed with a plurality of mark patterns having different rotation angles;
A detector for detecting charged particles reflected from the mark substrate;
A charged particle beam drawing apparatus comprising: Each of the plurality of mark patterns has a rectangular portion;
The charged particle beam drawing apparatus according to claim 1, wherein the sides of the rectangular portion of each mark pattern are non-parallel. Using the detection result of the detector, a calculation unit that calculates the waveform width of the scan waveform when the rectangular part of each mark pattern is scanned with a charged particle beam;
A selection unit for selecting a mark pattern that minimizes the waveform width;
The charged particle beam drawing apparatus according to claim 2, further comprising: Using the detection result of the detector, a calculation unit that calculates the waveform width of the scan waveform when the rectangular part of any one of the mark patterns is scanned while changing the direction with a charged particle beam;
A selection unit for selecting a mark pattern based on the waveform width for each scan direction and the rotation angle of the scanned mark pattern;
The charged particle beam drawing apparatus according to claim 2, further comprising: Scanning a plurality of mark patterns with different rotation angles formed on a mark substrate with a charged particle beam; and
Detecting charged particles reflected from the mark substrate with a detector;
Using the detection result of the detector, calculating a waveform width of a scan waveform when each mark pattern is scanned with a charged particle beam;
Selecting a mark pattern that minimizes the calculated waveform width;
Scanning the selected mark pattern with a charged particle beam during actual drawing, and obtaining beam resolution from the waveform width of the scan waveform; and
A method for measuring a beam resolution of a charged particle beam.

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