Data generation method, charged particle beam irradiation device and program

Abstract

To perform fast and accurate pixel coverage calculations for shapes including curves.SOLUTION: In a data generation method, a parametric curve that expresses the shape of a drawing pattern, and is defined by a plurality of control points arranged in order in a predetermined direction is divided at positions of extrema and inflection points to form a plurality of parametric elements, extract some of the control points from the plurality of control points for each parametric element, and generate a polygon by connecting the extracted control points in order in the predetermined direction, calculate the coverage rate by the polygon in each of the plurality of rectangular partitioned areas obtained by dividing an irradiation target of the charged particle beam into predetermined sizes, find intersections between the plurality of parametric elements and the four sides of the plurality of segmented areas, and calculate the coverage of the segmented area of the perimeter of the drawing pattern.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a data generation method, a charged particle beam irradiation device, and a program. [Background technology]

[0002] As LSIs become more highly integrated, the circuit line width required for semiconductor devices is becoming finer year by year. To form the desired circuit pattern on a semiconductor device, a method is adopted in which a high-precision master pattern formed on quartz is reduced and transferred onto a wafer using a reduction projection exposure apparatus. To produce the high-precision master pattern, a technique known as electron beam lithography is used, in which a resist is exposed to light by an electron beam drawing apparatus to form a pattern.

[0003] As an electron beam lithography device, for example, a multi-beam lithography device that uses multiple beams to irradiate many beams at once and improves throughput is known. In this multi-beam lithography device, for example, an electron beam emitted from an electron gun passes through an aperture member having multiple openings to form multiple beams, and each beam is blanked and controlled by a blanking plate. The beam that is not blocked is reduced in size by an optical system and irradiated at a desired position on a mask to be lithographed.

[0004] When performing electron beam lithography using a multi-beam lithography device, the coverage of an input figure is calculated for each pixel divided into sections of a specified size, and the dose of each beam is controlled. When an input figure includes curves, the coverage can be calculated relatively easily by approximating the figure to a polygon. However, when the approximation is performed with high accuracy, the number of vertices of the approximated polygon increases, which causes a problem that data processing takes a long time. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2008-9897 A [Patent Document 2] Japanese Patent Application Publication No. 8-149262 [Patent Document 3] JP 2019-57562 A [Patent Document 4] JP 2018-121139 A [Patent Document 5] JP 2006-38815 A [Patent Document 6] JP 2010-113624 A Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a data generation method, a charged particle beam irradiation device, and a program for quickly and accurately calculating pixel coverage of a figure including curves. [Means for solving the problem]

[0007] A data generation method according to one aspect of the present invention comprises: generating a plurality of parametric elements by dividing a parametric curve that represents a shape of a drawing pattern and is defined by a plurality of control points arranged in a predetermined direction, at the positions of extreme values ​​and inflection points; extracting some control points from the plurality of control points for each parametric element; generating a polygon by connecting the extracted control points in the predetermined direction; calculating the coverage by the polygon in each of a plurality of rectangular partitioned regions obtained by dividing an object to be irradiated with a charged particle beam by a predetermined size; determining the intersections between the plurality of parametric elements and the four sides of the plurality of partitioned regions; and calculating the coverage of the partitioned regions at the periphery of the drawing pattern.

[0008] A program according to one aspect of the present invention causes a computer to execute the following steps: generating a plurality of parametric elements by dividing a parametric curve that represents the shape of a drawing pattern, the parametric curve being defined by a plurality of control points arranged in sequence in a predetermined direction, at the positions of extreme values ​​and inflection points; generating a polygon by extracting some control points from the plurality of control points for each parametric element and connecting the extracted control points in sequence in the predetermined direction; calculating the coverage by the polygon in each of a plurality of rectangular partitioned regions obtained by dividing an object to be irradiated with a charged particle beam by a predetermined size; and determining the intersections between the plurality of parametric elements and the four sides of the plurality of partitioned regions, and calculating the coverage of the partitioned regions in the peripheral portion of the drawing pattern.

[0009] A charged particle beam irradiation device according to one embodiment of the present invention includes an irradiation unit that irradiates an object with a charged particle beam, and a control unit that divides a parametric curve that represents a shape of a drawing pattern, the parametric curve being defined by a plurality of control points arranged in a predetermined direction in sequence, at positions of extreme values ​​and inflection points to generate a plurality of parametric elements, extracts some control points from the plurality of control points for each parametric element, and generates a polygon by connecting the extracted control points in sequence in the predetermined direction, calculates the coverage by the polygon in each of a plurality of rectangular partitioned areas obtained by dividing the object to be irradiated with the charged particle beam by a predetermined size, finds the intersections between the plurality of parametric elements and four sides of the plurality of partitioned areas, calculates the coverage of the partitioned areas in the peripheral part of the drawing pattern, calculates the irradiation amount of each pixel based on the coverage, and controls the irradiation unit to obtain the calculated irradiation amount. Effect of the Invention

[0010] According to the present invention, pixel coverage of a figure including curves can be calculated quickly and accurately. [Brief description of the drawings]

[0011] [Figure 1]1 is a schematic diagram of a multi-charged particle beam writing apparatus according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a plan view of a shaping aperture array plate. [Diagram 3] 11 is a flowchart illustrating a drawing method. [Figure 4] FIG. 13 is a diagram illustrating a drawing operation. [Diagram 5] 1 is a flow chart illustrating a pixel map generation method. [Figure 6] FIG. 6a is a diagram showing an example of a B-spline curve, FIG. 6b is a diagram showing an example of a Bezier curve, and FIG. 6c is a diagram showing a conversion formula. [Figure 7] FIG. 7a is a diagram showing an example of a Bezier curve, FIG. 7b is a diagram showing an example of division of a Bezier curve, and FIG. 7c is a diagram showing an example of a Bezier element. [Figure 8] FIG. 8a is a diagram showing an example of a Bezier curve, FIG. 8b is a diagram showing an example of division of a Bezier curve, and FIG. 8c is a diagram showing an example of an internal polygon. [Figure 9] FIG. 9a is a diagram showing an example of classification of Bezier elements, and FIG. 9b is a diagram showing examples of Bezier basic elements. [Figure 10] 13 is a formula explaining a method for calculating an intersection point. [Figure 11] FIG. 13 is a diagram illustrating an example of an intersection point. [Figure 12] FIG. 13 is a diagram illustrating a method for calculating an intersection point. [Figure 13] FIG. 13 is a diagram illustrating an example of calculation of pixel coverage. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the embodiment, a configuration using an electron beam as an example of a charged particle beam will be described. However, the charged particle beam is not limited to an electron beam, and an ion beam or the like may be used.

[0013] Fig. 1 is a schematic diagram of a drawing apparatus according to an embodiment. As shown 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 lens barrel 102 and a drawing chamber 103. In the electron lens barrel 102, an electron gun 201, an illumination lens 202, a shaping aperture array plate 203, a blanking aperture array plate 204, a reduction lens 205, a limiting aperture member 206, an objective lens 207, and a deflector 208 are arranged.

[0014] An XY stage 105 is disposed in the writing chamber 103. A substrate 101 to be written is disposed on the XY stage 105. The substrate 101 is, for example, a mask blank or a semiconductor substrate (silicon wafer). In addition, a mirror 210 for position measurement is disposed on the XY stage 105.

[0015] The control unit 160 has a control computer 110, a deflection control circuit 130, a stage position detector 139, and a storage unit 140. Drawing data is input from the outside and stored in the storage unit 140. The drawing data defines information on a plurality of graphic patterns that describe the patterns to be formed on the substrate 101. As will be described later, the shape of the graphic pattern including a curve is defined by a cubic B-spline curve.

[0016] The control computer 110 has an area density calculation unit 111, an irradiation time calculation unit 112, a data processing unit 113, and a drawing control unit 114. Each unit of the control computer 110 may be configured with hardware such as an electric circuit, or may be configured with software such as a program that executes these functions. Alternatively, each unit may be configured with a combination of hardware and software.

[0017] A stage position detector 139 irradiates a laser onto a mirror 210 and receives the reflected light, thereby detecting the position of the XY stage 105 based on the principle of laser interference.

[0018] Fig. 2 is a conceptual diagram showing the configuration of the shaping aperture array plate 203. As shown in Fig. 2, the shaping aperture array plate 203 has a plurality of apertures 203a formed in the vertical direction (y direction) and horizontal direction (x direction) at a predetermined arrangement pitch. It is preferable that each aperture 203a is formed in a rectangular or circular shape of the same dimensions. Multi-beams 20a to 20e are formed by portions of the electron beam 200 passing through each of the plurality of apertures 203a.

[0019] In the blanking aperture array plate 204, a passage hole is formed in accordance with the arrangement position of each opening 203a of the shaping aperture array plate 203. In each passage hole, a blanker consisting of a pair of two electrodes is arranged. For example, one of the two electrodes of the blanker is grounded and kept at ground potential, and the other electrode is switched to ground potential or a potential other than ground potential, thereby switching the deflection of the beam passing through the passage hole on and off, thereby performing blanking control. When the blanker does not deflect the beam, the beam is turned on. When the blanker deflects the beam, the beam is turned off. In this way, the multiple blankers perform blanking deflection of the corresponding beams among the multi-beams that have passed through the multiple openings 203a of the shaping aperture array plate 203.

[0020] An electron beam 200 emitted from an electron gun 201 (emitter) illuminates the entire shaping aperture array plate 203 via an illumination lens 202. The electron beam 200 illuminates an area including all the apertures 203a. The electron beam 200 passes through the multiple apertures 203a of the shaping aperture array plate 203, thereby forming multiple electron beams (multi-beams) 20a to 20e, each having, for example, a rectangular shape.

[0021] The multiple beams 20a to 20e pass through the corresponding blankers of the blanking aperture array plate 204. The blankers blank and deflect the beams to be turned off among the electron beams passing through them individually. The blankers do not blank and deflect the beams to be turned on. The multiple beams 20a to 20e that have passed through the blanking aperture array plate 204 are reduced in size by the reduction lens 205 and travel toward the central opening formed in the limiting aperture member 206.

[0022] Here, the beam controlled to the beam-off state is deflected by the blanker and follows a trajectory that passes outside the opening of the limiting aperture member 206, and is therefore blocked by the limiting aperture member 206. On the other hand, the beam controlled to the beam-on state is not deflected by the blanker and passes through the opening of the limiting aperture member 206. In this way, blanking control is performed by turning the blanker deflection on / off, and the beam is controlled to be turned on / off. The blanking aperture array plate 204 functions as an irradiation time control unit that controls the irradiation time of each beam of the multi-beam.

[0023] The limiting aperture member 206 passes the beam deflected by the blanker of the blanking aperture array plate 204 to be in a beam-on state, and blocks the beam deflected by the blanker of the blanking aperture array plate 204 to be in a beam-off state. Then, the beams that pass through the limiting aperture member 206 and are formed from when the beam is turned on until when it is turned off form multiple beams for one shot.

[0024] The multi-beams that have passed through the limiting aperture member 206 are focused by the objective lens 207 to form a pattern image with a desired reduction ratio on the substrate 101. The beams (all of the multi-beams) that have passed through the limiting aperture member 206 are deflected collectively in the same direction by the deflector 208, and are irradiated onto a desired position on the substrate 101.

[0025] When the XY stage 105 is moving continuously, at least while the beam is being irradiated onto the substrate 101, the deflector 208 controls the irradiation position of the beam so as to follow the movement of the XY stage 105. The multiple beams irradiated at one time are ideally arranged at a pitch obtained by multiplying the arrangement pitch of the multiple openings 203a of the shaping aperture array plate 203 by the desired reduction ratio described above.

[0026] Next, the pattern drawing method according to this embodiment will be described with reference to the flowchart shown in FIG. 3. In the pattern area density calculation step (step S1), the area density calculation unit 111 virtually divides the drawing area of ​​the substrate 101 to be irradiated with the beam into a plurality of mesh areas. The size of the mesh area is, for example, approximately the same as that of one beam, and each mesh area becomes a pixel (unit irradiation area). The area density calculation unit 111 reads out the drawing data from the storage unit 140, and calculates the pattern area density (coverage) ρ of each pixel (rectangular partitioned area) using a pattern defined in the drawing data, and generates a pixel map that defines the coverage of each pixel. The method of generating the pixel map will be described later.

[0027] In the irradiation time calculation step (step S2), the irradiation time calculation unit 112 multiplies the pattern area density ρ by a reference irradiation amount D0 to calculate the irradiation amount ρD0 of the beam irradiated to each pixel. The irradiation time calculation unit 112 may further multiply by a correction coefficient for correcting the proximity effect, etc. The irradiation time calculation unit 112 divides the irradiation amount by the current amount of each of the multiple beams constituting the multi-beam to calculate the irradiation time of each of the multiple beams.

[0028] In the irradiation time control data generating step (step S3), the data processing unit 113 rearranges the irradiation time data in shot order according to the writing sequence, and generates irradiation time control data.

[0029] In the data transfer step (step S4), the drawing control unit 114 outputs the irradiation time control data to the deflection control circuit 130. The deflection control circuit 130 outputs the irradiation time control data to each blanker of the blanking aperture array plate 204.

[0030] In the drawing process (step S5), the drawing control unit 114 controls the drawing unit 150 to execute drawing processing on the substrate 101. Each blanker of the blanking aperture array plate 204 switches the beam on / off based on the irradiation time control data, and provides a desired exposure dose for each pixel.

[0031] Fig. 4 is a conceptual diagram for explaining the drawing operation. As shown in Fig. 4, a drawing region 80 on a substrate 101 is virtually divided into a plurality of rectangular stripe regions 82 with a predetermined width in the y direction (first direction). First, the XY stage 105 is moved and adjusted so that an irradiation region (beam array) 84 that can be irradiated with one multi-beam irradiation is positioned at the left end of the first stripe region 82, and drawing is started.

[0032] When writing the first stripe region 82, the XY stage 105 is moved in the -x direction to relatively advance writing in the +x direction. The XY stage 105 is moved continuously at a predetermined speed. After writing of the first stripe region 82 is completed, the stage position is moved in the -y direction and adjusted so that the beam array 84 is positioned at the right end of the second stripe region 82. Next, writing is performed in the -x direction by moving the XY stage 105 in the +x direction.

[0033] In the third stripe region 82, writing is performed in the +x direction, and in the fourth stripe region 82, writing is performed in the -x direction. Writing time can be reduced by alternately changing the direction. Also, each stripe region 82 may always be written in the same direction, that is, either the +x direction or the -x direction.

[0034] Next, a method for generating a pixel map by the area density calculation unit 111 will be described with reference to the flowchart shown in FIG.

[0035] The area density calculation unit 111 reads out the drawing data from the storage unit 140, and converts the curve of the figure pattern (drawing pattern) to be drawn, which is defined by a cubic B-spline curve, into a cubic Bezier curve (step S101). For example, the cubic B-spline curve shown in Fig. 6a is converted into the cubic Bezier curve shown in Fig. 6b. Fig. 6c shows an example of the conversion formula.

[0036] In a cubic Bezier curve, as shown in Fig. 7a, a curve is expressed by four control points. That is, in the example shown in Fig. 6b, a series of four control points surrounds the periphery of the figure. Of the four control points, two control points, the start point and the end point, are located on the curve. A number of control points are defined and placed in order in a predetermined clockwise or counterclockwise direction along the periphery of the figure.

[0037] The area density calculation unit 111 divides the curve represented by the four control points into finer Bezier curves at the positions of the extreme values ​​and inflection points (step S102). 2 / dt 2 )-(dPy / dt)(dPx 2 / dt 2 )=0. The extreme values ​​are the points where dPx / dt=0, dPy / dt=0.

[0038] Hereinafter, the Bezier curve divided at the positions of the extreme values ​​and the inflection points is called a Bezier element. For example, the Bezier curve shown in Fig. 7a includes one maximum value, one minimum value, and one inflection point, and is therefore divided into four Bezier elements B1 to B4 as shown in Fig. 7b.

[0039] As shown in FIG. 7c, each Bezier element is a curve element that monotonically increases or decreases in the X and Y directions.

[0040] Figure 8a is the same as figure 6b, showing the Bézier curve before division at the locations of the extremes and inflection points, and figure 8b shows the Bézier curve (Bézier elements) after division.

[0041] Next, for each of the multiple Bezier elements, some control points are extracted from the multiple control points, and the extracted control points are connected with straight lines in the original definition order (clockwise or counterclockwise around the periphery of the figure) to generate a polygon (hereinafter referred to as an "internal polygon") (step S103). In this embodiment, the start point and end point of each Bezier element are extracted to generate an internal polygon. For example, an internal polygon as shown in FIG. 8c is generated by connecting the start point and end point of each Bezier element shown in FIG. 8b in the definition order.

[0042] The internal polygon is divided into triangles by a conventionally known method (step S104). The polygons do not necessarily have to be triangles, and may be divided into trapezoids.

[0043] Using the triangles obtained by dividing the internal polygon, the coverage rate (area density) of each pixel by the internal polygon is calculated to generate a first pixel map (step S105).

[0044] Each Bezier element is classified into eight types shown in FIG. 9a based on the slope of the line segment connecting the start point and the end point and whether the control points other than the start point and the end point are located to the left or right of the progression direction of the line segment (step S106).

[0045] Each Bezier element is rotated and inverted so as to become a basic Bezier element shown in FIG. 9b (step S107).

[0046] For each pixel, it is determined whether the boundary line of the pixel intersects with the curve of the basic Bezier element (step S108). As shown in FIG. 10, the intersection points are found by solving a cubic equation that combines the Bezier curve and the straight line representing the pixel boundary. For example, intersection points P1 and P2 are found as shown in FIG. 11. At this time, if there is an intersection point on the left side L or the bottom side B of the pixel, the remaining intersection points exist on the top side T or the right side R. If there is no intersection point on the left side L or the bottom side B, there is no intersection point at this pixel. There are a maximum of two intersection points per pixel. By taking these things into consideration, the intersection determination can be performed efficiently.

[0047] As shown in Fig. 12, the intersection determination is performed by dividing the curve from t=0 to t=1 by Δt, calculating the coordinates on the curve at each position, and finding the point t that exceeds the coordinate value of the pixel boundary for which the intersection is to be found within Δt. i and the previous point t i-1 The calculation may be performed by linear interpolation based on the value of Δt. In this case, the interpolation calculation is performed for t based on each coordinate value. Here, the coordinate calculation for each Δt may be performed in parallel using threads such as a GPU.

[0048] When the boundary line of a pixel intersects with a curve of a Bezier element, the pixel is divided into a triangular portion (A1, A3) and a curved fan portion (A2) as shown in Figure 13, and the area of ​​each is calculated. The area of ​​the curved fan portion is calculated by the line integral that covers the intersection point with the pixel.

[0049] The areas of the triangular portion and the curved fan portion are added together to calculate the pixel coverage rate, and a second pixel map is generated (step S109). The coverage rate calculated here is the coverage rate of the pixels on the periphery (outer periphery) of the figure (drawing pattern). Note that if the Bezier element is located inside the line of the internal polygon, the calculated coverage rate is multiplied by -1.

[0050] A third pixel map is generated by adding the second pixel map that has been subjected to the inverse rotation and flipping operation performed in step S107 to the first pixel map generated in step S105 (step S110). This third pixel map is used when the irradiation time calculation unit 112 calculates the beam irradiation amount to be irradiated to each pixel.

[0051] In this way, according to this embodiment, the Bezier curve is divided into fine Bezier curves (Bezier elements) at the extreme values ​​and inflection points, so that the number of intersections between each pixel and the Bezier elements is limited to a maximum of two, making it easier to calculate the intersections and coverage, and allowing pixel coverage calculations to be performed quickly and accurately.

[0052] If the method according to the above embodiment is not used, a Bezier curve (parametric curve) may cross one side of a partitioned region (pixel) multiple times or cross three or more sides depending on the degree of the curve, and the coverage rate must be calculated taking into account various ways of crossing, leading to an increase in the amount of processing. On the other hand, if a parametric curve is divided at extreme values ​​and inflection points as in the above embodiment, the curve elements after division will have a shape that monotonically increases or decreases in one direction. Therefore, when a curve element crosses four sides (right side, upper side, left side, and lower side) of the boundary of the partitioned region, the number of crossings will be two, and the curve element crosses different sides. Therefore, the method of crossing the curve element with the boundary of the partitioned region is simplified, the coverage rate calculation becomes easier, and the amount of processing can be reduced. In addition, the number of elements to be processed is smaller than in the conventional coverage rate calculation using polygon approximation, and since no approximation is performed, the coverage rate can be calculated quickly and accurately.

[0053] The Bézier elements generated by dividing a Bézier curve can be used as units of parallel processing, for example, they can be effectively used in parallel calculations on a GPU, enabling high-speed processing.

[0054] In the above embodiment, an example of converting into a cubic Bezier curve has been described, but the degree is not limited to three.

[0055] In the above embodiment, an example has been described in which the input figure is expressed by a B-spline, but a figure expressed by other parametric curves may be used as input data as long as it can be converted into a Bezier curve.

[0056] The above processing may be performed on parametric curves other than Bézier curves. A parametric curve is divided at the positions of extreme values ​​and inflection points to generate a plurality of parametric elements. At least one of a plurality of control points included in each parametric element is connected in order with a line to generate an internal polygon. The pixel coverage rate on the periphery of the figure is calculated by determining the intersections of the plurality of parametric elements and pixel boundaries, and the coverage rate of each pixel is determined from this and the pixel coverage rate of the internal polygon.

[0057] In the above embodiment, a drawing device that draws a pattern on a substrate has been described, but the present invention can also be applied to other irradiation devices that irradiate a beam to an object, such as an inspection device. In addition, in the above embodiment, a multi-beam irradiation device that irradiates many beams at once using multiple beams has been described, but the same method can also be applied to a single-beam irradiation device that irradiates a substrate to be irradiated with one beam.

[0058] At least a part of the control computer 110 may be configured with hardware or software. When configured with software, a program that realizes at least a part of the functions of the control computer 110 may be stored in a recording medium such as a flexible disk or a CD-ROM, and may be read and executed by a computer. The recording medium is not limited to removable ones such as a magnetic disk or an optical disk, but may be a fixed recording medium such as a hard disk device or a memory.

[0059] Also, a program for realizing at least a part of the functions of the control computer 110 may be distributed via a communication line (including wireless communication) such as the Internet. Furthermore, the program may be encrypted, modulated, or compressed and distributed via a wired line or wireless line such as the Internet, or stored in a recording medium.

[0060] The present invention is not limited to the above-described embodiment, and the components can be modified and embodied in the implementation stage without departing from the gist of the invention. In addition, various inventions can be formed by appropriately combining the multiple components disclosed in the above-described embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, components from different embodiments may be appropriately combined. [Explanation of symbols]

[0061] 100 Drawing device 110 Control computer 111 Area density calculation section 112 Irradiation time calculation unit 113 Data Processing Unit 114 Drawing control unit

Claims

1. a parametric curve expressing a shape of a drawing pattern, the parametric curve being defined by a plurality of control points arranged in a predetermined direction, is divided at positions of extreme values ​​and inflection points to generate a plurality of parametric elements; For each parametric element, a portion of the control points is extracted from the plurality of control points, and a polygon is generated by sequentially connecting the extracted control points in the predetermined direction; calculating a coverage rate of the polygon in each of a plurality of rectangular partitioned regions obtained by dividing an object to be irradiated with the charged particle beam by a predetermined size; a data generating method for calculating a coverage of a peripheral portion of the drawing pattern by determining intersections between the plurality of parametric elements and four sides of the plurality of divided regions;

2. 2. The data generating method according to claim 1, wherein the parametric curve is a Bezier curve.

3. Dividing the Bézier curve at locations of extrema and inflection points to generate a plurality of Bézier elements; 3. The data generation method according to claim 2, further comprising the steps of: extracting a start point and an end point from a plurality of control points included in each of the plurality of Bezier elements; and generating the polygon by connecting the extracted start points and end points in the predetermined direction in order with straight lines.

4. A step of dividing a parametric curve representing a shape of a drawing pattern, the parametric curve being defined by a plurality of control points arranged in a predetermined direction, at positions of extreme values ​​and inflection points to generate a plurality of parametric elements; A step of extracting some control points from the plurality of control points for each parametric element, and generating a polygon by sequentially connecting the extracted control points in the predetermined direction; A step of calculating a coverage rate of the polygon in each of a plurality of rectangular partitioned regions obtained by dividing an irradiation target of the charged particle beam by a predetermined size; determining points of intersection between the plurality of parametric elements and four sides of the plurality of partitioned regions, and calculating a coverage rate of the partitioned regions at a periphery of the writing pattern; A program that causes a computer to execute the following.

5. an irradiation unit that irradiates a charged particle beam onto an object; a control unit that generates a plurality of parametric elements by dividing a parametric curve representing a shape of a writing pattern, the parametric curve being defined by a plurality of control points arranged in a predetermined direction, at positions of extreme values ​​and inflection points, extracting some control points from the plurality of control points for each parametric element, generating a polygon by connecting the extracted control points in the predetermined direction, calculating a coverage by the polygon in each of a plurality of rectangular partitioned regions obtained by dividing an object to be irradiated with the charged particle beam by a predetermined size, determining points of intersection between the plurality of parametric elements and four sides of the plurality of partitioned regions, calculating a coverage by the partitioned regions of a peripheral portion of the writing pattern, calculating an irradiation amount for each pixel based on the coverage, and controlling the irradiation unit to achieve the calculated irradiation amount; A charged particle beam irradiation device comprising:

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