Data processing method, charged particle beam irradiation device, and computer-readable recording medium

Abstract

The purpose of the present invention is to quickly and accurately calculate information necessary for performing image processing on such as a pixel intersection of a graphic including a curve. In the data processing method according to the present embodiment, the positions of a plurality of control points of a first parametric curve representing the shape of a circuit pattern are rounded onto grids having predetermined intervals, a table is searched in which parameters obtained from the positions of the control points and the curve are defined for each of a plurality of second parametric curves, the parameters of the second parametric curves having control points having the same positional relationship with the plurality of control points rounded onto the grids are referred, and information used for image processing of the circuit pattern is calculated.

Description

Data processing method, charged particle beam irradiation device, and computer-readable recording medium

[0001] The present invention relates to a data processing method, a charged particle beam irradiation device, and a computer-readable recording medium.

[0002] With the increasing integration density of LSIs, the circuit line width required for semiconductor devices has been getting 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 called electron beam lithography is used, in which a resist is exposed to light using an electron beam writing apparatus to form the pattern.

[0003] One known electron beam lithography device is a multi-beam lithography device that uses multiple beams to irradiate multiple beams at once, improving throughput. 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 blanking of each beam is controlled by a blanking plate. The unblocked beam is reduced in size by an optical system and irradiated onto a desired position on a mask to be lithographed.

[0004] When electron beam lithography is performed using a multi-beam lithography system, the coverage of the input figure is calculated for each pixel divided into sections of a predetermined size, and the irradiation amount for each beam is controlled. If the input figure includes a curve, the intersection points between the curve and the section boundary are calculated, and the coverage is determined using the intersection points. However, there was a problem in that the processing load for the intersection point calculation increased as the degree of the curve increased.

[0005] Approximating a curve to a polygon makes it relatively easy to calculate intersections. However, when the approximation is performed with high precision, the number of vertices in the approximated polygon increases, which can result in a problem of requiring a significant amount of time for data processing.

[0006] Special table 2016-520920 publication JP 2022-053208 publication JP 08-016643 publication

[0007] An object of the present invention is to provide a data processing method, a charged particle beam irradiation device, and a computer-readable recording medium that quickly and accurately calculate information required for image processing, such as pixel intersections of figures including curves.

[0008] A data processing method according to one aspect of the present invention involves rounding the positions of a plurality of control points of a first parametric curve that represents the shape of a circuit pattern onto a grid with a predetermined spacing, searching a table that defines the positions of the control points and parameters determined from the curve for each of a plurality of second parametric curves, and referencing the parameters of a second parametric curve that has control points that have the same positional relationship as the plurality of control points rounded onto the grid, and calculating information to be used in image processing of the circuit pattern.

[0009] A computer-readable recording medium according to one aspect of the present invention records a program that causes a computer to execute the following steps: rounding the positions of a plurality of control points of a first parametric curve that represents the shape of a circuit pattern onto a grid with a predetermined spacing; and searching a table that defines, for each of a plurality of second parametric curves, the positions of the control points and parameters determined from the curve, and referring to the positions and corresponding parameters of the plurality of points of a second parametric curve that has control points that have the same positional relationship as the plurality of control points rounded onto the grid, and calculating information to be used in image processing of the circuit pattern.

[0010] A charged particle beam irradiation device according to one aspect of the present invention includes an irradiation unit that irradiates an object with a charged particle beam; a memory unit that stores a table in which, for each of a plurality of second parametric curves, positions of control points and parameters calculated from the curve are defined; and a control unit that rounds the positions of the plurality of control points of a first parametric curve that represents the shape of a circuit pattern onto a grid with a predetermined interval, searches the table, refers to the positions and corresponding parameters of the plurality of points of a second parametric curve that has control points that have the same positional relationship as the plurality of control points rounded onto the grid, calculates information to be used for image processing of the circuit pattern, and controls the irradiation unit using the calculated information.

[0011] According to the present invention, it is possible to quickly and accurately calculate information required for image processing, such as pixel intersections of a figure including curves.

[0012] FIG. 1 is a schematic diagram of a multi-charged particle beam writing apparatus according to an embodiment of the present invention; FIG. 2 is a plan view of a shaping aperture array substrate; FIG. 3A to FIG. 3D are diagrams illustrating monotonically increasing or monotonically decreasing curves; FIG. 4 is a diagram illustrating an example of a cubic Bezier curve; FIG. 5 is a diagram illustrating an example of a table defining the relationship between parameters and positions on the curve; FIG. 6 is a flowchart illustrating a drawing method; FIG. 7 is a diagram illustrating drawing operations; and FIG. 8 is a flowchart illustrating a pixel map generation method. FIG. 10A is a diagram illustrating an example of a B-spline curve, FIG. 10B is a diagram illustrating an example of a Bezier curve, and FIG. 10C is a diagram illustrating a conversion formula. FIG. 11A is a diagram illustrating an example of a Bezier curve, FIG. 11B is a diagram illustrating an example of division of a Bezier curve, and FIG. 11C is a diagram illustrating an example of a Bezier curve after division. FIG. 11B is a diagram illustrating an example of a Bezier curve after division. FIG. 11C is a diagram illustrating an example of rounding of control points. FIG. 2 is a diagram illustrating an example of pixel intersections. FIG. 2 is a diagram illustrating an example of calculation of pixel coverage. FIG. 3 is a diagram illustrating an example of the center of gravity of a Bezier curve.

[0013] 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 also be used.

[0014] FIG. 1 is a schematic diagram of a lithography apparatus 100 according to an embodiment. As shown in FIG. 1, the lithography apparatus 100 includes a lithography unit 150 and a control unit 160. The lithography apparatus 100 is an example of a multi-charged particle beam lithography apparatus. The lithography unit 150 includes an electron optical column 102 and a lithography chamber 103. Inside the electron optical column 102, an electron gun 201, an illumination lens 202, a shaping aperture array substrate 203, a blanking aperture array substrate 204, a reduction lens 205, a limiting aperture member 206, an objective lens 207, and a deflector 208 are arranged.

[0015] An XY stage 105 is disposed in the patterning chamber 103. A substrate 101 to be patterned is disposed on the XY stage 105. The substrate 101 is, for example, a mask blank or a semiconductor substrate (silicon wafer). A position measurement mirror 210 is also disposed on the XY stage 105.

[0016] The control unit 160 has a control computer 110, a deflection control circuit 130, a stage position detector 139, and memory units 140, 142, and 144. Drawing data is input from the outside and stored in the memory unit 140. The drawing data defines information on a plurality of graphic patterns that describe the semiconductor circuit pattern to be formed on the substrate 101. The graphic patterns include curves, and the shapes of the patterns are defined by, for example, cubic B-spline curves.

[0017] The storage unit 142 stores a table that defines the positions of control points and positions on the Bezier curve corresponding to a plurality of parameters for each of a plurality of shapes of Bezier curves. The method of creating the table will be described later.

[0018] The control computer 110 includes an area density calculation unit 111, an irradiation time calculation unit 112, a data processing unit 113, and a writing 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, the control computer 110 may be configured with a combination of hardware and software. When configured with software, a program that realizes at least some of the functions of the control computer 110 is stored in a storage unit 144 (recording medium) such as a flexible disk or CD-ROM. The control computer 110 is a computer having a CPU, and the CPU reads and executes the program. The storage unit 144 is not limited to a removable storage device such as a magnetic disk or optical disk, but may also be a fixed storage device such as a hard disk drive or memory.

[0019] The stage position detector 139 irradiates the mirror 210 with a laser beam and receives the reflected light to detect the position of the XY stage 105 based on the principle of laser interference.

[0020] 2 is a conceptual diagram showing the configuration of the shaping aperture array substrate 203. As shown in FIG. 2, a plurality of apertures 203a are formed in the shaping aperture array substrate 203 at a predetermined arrangement pitch along the vertical direction (y direction) and horizontal direction (x direction). It is preferable that each aperture 203a is formed in the same rectangular or circular shape with the same dimensions. A portion of the electron beam 200 passes through each of the plurality of apertures 203a, thereby forming a multibeam 20.

[0021] The blanking aperture array substrate 204 has passage holes formed in alignment with the positions of the apertures 203a of the shaping aperture array substrate 203. A blanker, consisting of a pair of two electrodes, is disposed in each passage hole. 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 controlling blanking. 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 multiple beams that have passed through the multiple apertures 203a of the shaping aperture array substrate 203.

[0022] An electron beam 200 emitted from an electron gun 201 (emitting section) illuminates the entire shaping aperture array plate 203 via an illumination lens 202. The electron beam 200 illuminates an area that includes all of the apertures 203a. The electron beam 200 passes through the multiple apertures 203a in the shaping aperture array plate 203, thereby forming a multibeam 20 including multiple individual beams. The overall shape of the beam array of the multibeam 20 is, for example, rectangular.

[0023] The individual beams that make up the multi-beam 20 pass through corresponding blankers on the blanking aperture array substrate 204. The blankers blank out the individual beams that are to be turned off. The blankers do not blank out the individual beams that are to be turned on. The multi-beam 20 that has passed through the blanking aperture array substrate 204 is reduced by a reduction lens 205 and travels toward a central opening formed in a limiting aperture member 206.

[0024] Here, an individual 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, an individual 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 and off, and the individual beams are controlled to be turned on and off. The blanking aperture array substrate 204 functions as an irradiation time control unit that controls the irradiation time of each beam of the multi-beam.

[0025] The limiting aperture member 206 passes the individual beams deflected by the blankers of the blanking aperture array substrate 204 to be in a beam-on state, and blocks the individual beams deflected by the blankers of the blanking aperture array plate 204 to be in a beam-off state. Then, the beams formed from when the beams are turned on until when the beams are turned off and which have passed through the limiting aperture member 206 form a multi-beam for one shot.

[0026] 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 (the entire multi-beams) that have passed through the limiting aperture member 206 are deflected together in the same direction by the deflector 208, and are irradiated onto a desired position on the substrate 101.

[0027] When the XY stage 105 is moving continuously, the deflector 208 controls the irradiation position of the beam so that it follows the movement of the XY stage 105, at least while the beam is being irradiated onto the substrate 101. Ideally, the multiple beams irradiated at one time are arranged at a pitch obtained by multiplying the arrangement pitch of the plurality of openings 203a in the shaping aperture array substrate 203 by the desired reduction ratio described above.

[0028] Next, a method for creating the table stored in the storage unit 142 will be described. The graphic pattern to be drawn contains a plurality of frequently used curves. These curves are represented by cubic Bezier curves (second-order parametric curves), and a table is created that defines the positions of the control points of the cubic Bezier curves and the positions on the Bezier curves corresponding to a plurality of parameters. The cubic Bezier curves defined in the table are monotonically increasing curves as shown in FIGS. 3A and 3B, or monotonically decreasing curves as shown in FIGS. 3C and 3D. While this embodiment describes an example in which a Bezier curve is used, other parametric curves, such as a Nurbs curve, may also be used.

[0029] A cubic Bezier curve is expressed by four control points, as shown in FIG. ０ ~P ３ Among them, the starting point P ０ and the end point P ３ The two control points (end points) of the starting point P are located on the curve. ０ is the reference point (origin), and the other three control points P １ ~P ３ The position of the control point P ０ ~P ３ is positioned on a grid with a predetermined spacing. The grid spacing is determined depending on the required accuracy. For example, the grid spacing is about 1 / 100 to 1 / 200 of the size of the Bezier curve in the X or Y direction.

[0030] A cubic Bezier curve is a parametric curve, and the curve (x(t), y(t)) is expressed by a parameter t (0≦t≦1). As shown in FIG. 5, t=0 is the starting point P ０ t=1 corresponds to the end point P ３The positions (x coordinate, y coordinate) on the curve for multiple values ​​of t are defined in a table. For example, the parameter t ranging from 0 to 1 is divided into 100 equal parts, and the positions on the curve for each value of t are defined in a table.

[0031] Figure 6 shows an example of values ​​defined in the table. ０ is used as the reference point, and the other three control points P １ ~P ３ The coordinates of the point on the curve when the parameter t = 0.01 (X １ , Y １ ), the position of the point on the curve at t = 0.02 (X ２ , Y ２ ), ..., the position of the point on the curve at t = 0.99 (X ９９ , Y ９９ ) is defined in the table.

[0032] A table defining information such as that shown in FIG. 6 for Bezier curves of a plurality of shapes is created in advance and stored in the storage unit 142. Bezier curves whose information is defined in the table are often used in graphic patterns. Alternatively, graphic patterns described in the drawing data in the storage unit 140 may be analyzed, and information such as that shown in FIG. 6 may be defined in the table for Bezier curves of frequently used shapes.

[0033] Next, the pattern writing method according to this embodiment will be described with reference to the flowchart shown in FIG. 7 . In the pattern area density calculation step (step S1), the area density calculation unit 111 virtually divides the writing area of ​​the substrate 101 into a plurality of rectangular mesh areas (divided areas). The size of the mesh areas is, for example, approximately the same as that of one beam, and each mesh area serves as a pixel (unit irradiation area). The area density calculation unit 111 reads writing data from the storage unit 140, calculates the pattern area density (coverage) ρ of each pixel using a pattern defined in the writing data, and generates a pixel map that defines the coverage of each pixel. The method for generating the pixel map will be described later.

[0034] In the irradiation time calculation step (step S2), the irradiation time calculation unit 112 calculates the reference irradiation amount D０ and multiplying it by ρD to obtain the beam irradiation dose ρD ０ The irradiation time calculation unit 112 may further multiply the irradiation amount 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.

[0035] In the irradiation time control data generation 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.

[0036] In the data transfer step (step S4), the writing 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.

[0037] 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 and off based on the irradiation time control data, thereby providing a desired exposure dose for each pixel.

[0038] 8 is a conceptual diagram for explaining the drawing operation. As shown in Fig. 8, a drawing region 80 on a substrate 101 is virtually divided into a plurality of rectangular stripe regions 82 each having 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 a single multi-beam irradiation is positioned at the left end of the first stripe region 82, and drawing begins.

[0039] When writing the first stripe region 82, the XY stage 105 is moved in the -x direction, thereby relatively progressing writing in the +x direction. The XY stage 105 is moved continuously at a predetermined speed. After writing the first stripe region 82 is completed, the stage position is moved in the -y direction, and the beam array 84 is adjusted to be positioned at the right end of the second stripe region 82. Next, the XY stage 105 is moved in the +x direction, thereby writing in the -x direction.

[0040] 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. Alternatively, each stripe region 82 may always be written in the same direction, that is, in either the +x direction or the -x direction.

[0041] Next, a pixel map generation method performed by the area density calculation unit 111 will be described with reference to the flowchart shown in FIG.

[0042] The area density calculation unit 111 reads out the drawing data from the storage unit 140 and converts the curves of the figure pattern defined by the cubic B-spline curves into cubic Bezier curves (step S101). For example, the cubic B-spline curve shown in Fig. 10A is converted into the cubic Bezier curve shown in Fig. 10B. Fig. 10C shows an example of the conversion formula.

[0043] A cubic Bezier curve is expressed using four control points, as shown in Fig. 11A. In other words, in the example shown in Fig. 10B, a series of four control points surrounds the periphery of the figure. Of the four control points, two control points (end points), the start point and the end point, are located on the curve.

[0044] 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 and dPy / dt = 0.

[0045] For example, the Bezier curve shown in FIG. 11A includes one maximum value, one minimum value, and one inflection point, and is therefore divided into four Bezier curves B1 to B4 as shown in FIG. 11B.

[0046] As shown in FIG. 11C, the Bezier curve (first parametric curve) after division becomes a curve element that monotonically increases or monotonically decreases in the X and Y directions.

[0047] The area density calculation unit 111 calculates the intersections of each divided Bezier curve with the boundaries of the mesh regions (pixels) (step S103).

[0048] In the calculation of intersections, the area density calculation unit 111 first selects one of the multiple Bezier curves after division that has not yet been selected, and then rounds the four control points of the selected Bezier curve onto a grid with a predetermined spacing, which is the same as the grid spacing used when creating the table.

[0049] FIG. 12 shows the control point P １ Here is an example of rounding onto a grid, i.e., moving onto the nearest grid.

[0050] The area density calculation unit 111 searches the table in the storage unit 142 to determine whether a curve having control points in the same positional relationship as the four control points after rounding onto the grid is defined. When determining whether a curve has control points in the same positional relationship, for example, the value defined in the table is the starting point P ０ is used as the reference point, and the other three control points P １ ~P ３ When the coordinates of the starting point P of the Bezier curve are defined in a table, the starting point P of the Bezier curve is rounded on the grid of the predetermined interval. ０ is used as the reference point, and the other three control points P １ ~P ３ If a curve with the same positional relationship between the four control points is defined in the table, the area density calculation unit 111 refers to the relationship between the parameter t in the table and the position on the curve, and calculates the intersection with the boundary of the mesh region.

[0051] For example, when calculating the position of the intersection point K1 shown in FIG. 13, the X coordinate X Ｌｅｆｔ is known, and the X-position X corresponding to the parameter t=0.01 to 0.99 defined in the table shown in FIG. １ ~X ９９ Refer to X ｉ ≦X Ｌｅｆｔ ≦X ｉ＋１ Then, find the i that is closest to the boundary. ｉ , X ｉ＋１ Using the parameters corresponding to Ｌｅｆｔ The parameter t corresponding to X is calculated by interpolation. Ｌｅｆｔ The Y coordinate on the curve is calculated from the parameter t corresponding to the intersection point K1, and the position of the intersection point K1 is found.

[0052] For example, X ２５ ≦X Ｌｅｆｔ ≦X ２６ By interpolation, X Ｌｅｆｔ The parameter t corresponding to t=0.254 is calculated as 0.254. ２５ and Y ２６ The position of the intersection point K1 is calculated from the above.

[0053] The position of the intersection point K2 shown in Figure 13 can be determined in a similar manner. Ｔｏｐ is known, and the Y position Y corresponding to the parameter t=0.01 to 0.99 defined in the table shown in FIG. １ ~Y ９９ Refer to Y ｊ ≦Y Ｔｏｐ ≦Y ｊ＋１ Then, find j such that Y ｊ , Y ｊ＋１ Using the parameters corresponding to Ｔｏｐ The parameter t corresponding to Y is calculated by interpolation. Ｔｏｐ The X coordinate on the curve is calculated from the parameter t corresponding to the intersection point K2, and the position of the intersection point K2 is found.

[0054] This method rounds the control points of the Bezier curve onto a grid and calculates the parameter t of the intersection point K1 by interpolation, so the calculated position of the intersection point K1 deviates from the true value, but the difference from the true value is small. The narrower the grid spacing, the smaller this difference becomes. By referencing the values ​​in the table, the position of the intersection point K1 can be calculated quickly and accurately while reducing the amount of calculation required to calculate the position of the intersection point K1.

[0055] If a curve with the same positional relationship between the four control points is not defined in the table, known curve processing is performed to calculate the intersection with the boundary of the mesh region. In this case, the amount of calculation required for intersection calculation is greater than when using a table reference method.

[0056] The area density calculation unit 111 sequentially selects all (post-division) Bezier curves surrounding the periphery of the figure, performs the above process, and calculates the intersections with the boundaries of the mesh region.

[0057] The area density calculation unit 111 uses the calculated intersection points to calculate the coverage (area density) of each pixel using a known method and generates a pixel map (step S104). For example, as shown in FIG. 14, the pixel is divided into a triangular portion (A1, A3) and a curved fan portion (A2), and the area of ​​each is calculated. The area of ​​the curved fan portion is calculated by a line integral over the pixel intersection points. The coverage of the pixel is calculated by adding the areas of the triangular portion and the curved fan portion. The pixel map is used when the irradiation time calculation unit 112 calculates the beam dose irradiated to each pixel.

[0058] As described above, according to this embodiment, the control points of the Bezier curve are rounded onto a grid, and the parameter t of the intersection between the pixel boundary (the boundary of the pixel; the boundary of the mesh area) and the Bezier curve is calculated by interpolation, thereby making it possible to calculate the intersection quickly and with high accuracy according to the grid spacing.

[0059] In the above embodiment, an example has been described in which the parameter t in the range of 0 to 1 is equally divided, and the positions (x coordinate, y coordinate) of points on the Bezier curve corresponding to each parameter value are defined in a table, but it is also possible to equally divide the size of the Bezier curve in the X direction, and define the value of the parameter t and the y coordinate corresponding to each x coordinate point in a table. Also, it is possible to divide the Bezier curve finely in the X direction in areas where the Y direction change is large, and to divide it roughly in the X direction in areas where the Y direction change is small, and define the value of the parameter t and the y coordinate corresponding to the divided x coordinate points in a table.

[0060] A plurality of tables with different division numbers for the parameter t in the range of 0 to 1 may be created and stored in the storage unit 142. A table with a large number of division numbers is suitable for high-precision drawing, and a table with a small number of division numbers is suitable for high-speed drawing with reduced precision. The area density calculation unit 111 switches between the tables to be used depending on the required drawing precision.

[0061] A table may be created by normalizing a Bezier curve. For example, the X position of the start point of the Bezier curve is normalized to 0 and the X position of the end point to 1. The control points of the normalized Bezier curve are positioned on a grid. The normalized Bezier curve is divided in the X direction at a predetermined index size, and a table is created that defines the value of the parameter t corresponding to each division point. When calculating the intersection point, the Bezier curve to be calculated is normalized, the normalized control points are rounded onto a grid, the table is searched, and a curve with the same positional relationship of the four control points rounded onto the grid is extracted. The parameters corresponding to the division points of the extracted curve are referenced, and the parameter t of the intersection point is calculated by linear interpolation.

[0062] In the above embodiment, an example was described in which a table that associates the parameter t of a Bezier curve with a position on the curve is prepared, and an intersection calculation is performed to find the pixel coverage by referring to the table. However, a table may also be created that defines the line segment connecting the start point and end point of the Bezier curve and the center of gravity of the area enclosed by the Bezier curve.

[0063] For example, as shown in FIG. 15, the starting point P ０ is the reference point (origin), and the other three control points P １ ~P３ and the starting point P ０ and end point P ３ A table is created that associates the line segments connecting the control points P with the center of gravity G of the area enclosed by the Bezier curve. ０ ~P ３ The center of gravity G is located on a grid with a predetermined spacing. ０ ~P ３ The center of gravity can be calculated from the position of the object by known center of gravity calculation.

[0064] The center of gravity is calculated when correcting the dose in the pattern drawing process. The control points of the Bezier curve to be calculated are rounded onto a grid, and a table is searched to extract the center of gravity associated with the curve that has control points that are in the same positional relationship as the four control points rounded onto the grid. Because the control points of the Bezier curve to be calculated are rounded onto a grid, the calculated center of gravity position deviates from the true value, but the difference from the true value is small. By using the values ​​in the table, the center of gravity position can be determined quickly and accurately while keeping the amount of calculations low.

[0065] A Bézier curve may be normalized to create a center of gravity table. For example, the Bézier curve is translated, rotated, and scaled, and normalized so that the start point is (0,0) and the end point is (1,0). The control points of the normalized Bézier curve are positioned on a grid. A table is created that associates the centers of gravity with the positions of the normalized control points. When calculating the center of gravity, the Bézier curve to be calculated is normalized, the normalized control points are rounded onto a grid, and the table is searched to extract the center of gravity associated with a curve having control points that are in the same positional relationship as the four control points rounded onto the grid. The extracted center of gravity position is then subjected to the inverse transformation (translation, rotation, and scaling) performed when normalizing the Bézier curve, to find the center of gravity.

[0066] Bezier curve starting point P ０ is the reference point (origin), and the other three control points P １ ~P ３ and the starting point P ０ and end point P ３A table may be created that associates the area of ​​the region enclosed by the line segments connecting the four Bezier curves with the area of ​​the region enclosed by the Bezier curve. Area calculations are performed during proximity effect correction and other processes in pattern drawing processing. The control points of the Bezier curve to be calculated are rounded onto a grid, and the table is searched to extract the area associated with a curve that has control points that are in the same positional relationship as the four control points rounded onto the grid. Because the control points of the Bezier curve to be calculated are rounded onto a grid, the calculated area deviates from the true value, but the difference from the true value is small. By using the values ​​in the table, the area can be calculated quickly and accurately while reducing the amount of calculation.

[0067] Bezier curve starting point P ０ is the reference point (origin), and the other three control points P １ ~P ３ A table may be created that associates the position of each curve with the curvature of the Bezier curve. Curvature calculations are performed during bias correction and other processes in the pattern drawing process. The control points of the Bezier curve to be calculated are rounded onto a grid, and the table is searched to extract the curvature associated with a curve that has control points that are in the same positional relationship as the four control points rounded onto the grid. Because the control points of the Bezier curve to be calculated are rounded onto a grid, the calculated curvature deviates from the true value, but the difference from the true value is small. By using the values ​​in the table, the curvature can be calculated quickly and accurately while reducing the amount of calculation.

[0068] A table is created according to the image processing of the circuit pattern to be performed, such as calculating the intersection point between the pixel boundary and the Bezier curve, calculating the position of the center of gravity of the area surrounded by the Bezier curve and the line segment connecting the start point and end point of the Bezier curve, calculating the area of ​​the area surrounded by the Bezier curve and the line segment connecting the start point and end point of the Bezier curve, and calculating the curvature of the Bezier curve, and the table is stored in the memory unit 142.

[0069] In the above embodiment, an example has been described in which a curve of a graphic pattern defined by a cubic B-spline curve is converted into a cubic Bezier curve, but the degree of a parametric curve is not limited to 3. Similarly, the degree of a Bezier curve defined in a table is not limited to 3.

[0070] In the above embodiment, an example was described in which the input graphic was expressed by a B-spline, but graphics expressed by other parametric curves may also be used as input data as long as they can be converted into Bezier curves.

[0071] The table stored in the storage unit 142 may reduce the number of data patterns defined in the table by reusing the defined data by inverting or rotating it. The table may be stored in another computer connected via a network.

[0072] 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 target with a beam, such as an inspection device. For example, one inspection method for a pattern inspection device that inspects mask defects is "die-to-database inspection," in which drawing data (semiconductor circuit data) is input into the inspection device, a reference image is generated based on the data, and the reference image is compared with an optical image that serves as measurement data obtained by capturing the pattern. The method of the above embodiment can be used when performing image processing to generate a reference image from drawing data.

[0073] Furthermore, in the above embodiment, a multi-beam irradiation device that uses multiple beams to irradiate many beams at once has been described, but the same technique can also be applied to a single-beam irradiation device that irradiates a substrate to be irradiated with one beam.

[0074] A program that realizes 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 on a recording medium.

[0075] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications are possible within the scope of the effects of the invention. This application is based on Japanese Patent Application No. 2024-099822 filed on June 20, 2024, the entire contents of which are incorporated by reference.

[0076] 100 lithography device 110 control computer 111 area density calculation unit 112 irradiation time calculation unit 113 data processing unit 114 lithography control unit

Claims

1. A data processing method that calculates information used in image processing of the circuit pattern by rounding the positions of multiple control points of a first parametric curve that represents the shape of the circuit pattern onto a grid with a predetermined spacing, searching a table that defines the positions of the control points and parameters calculated from the curve for each of multiple second parametric curves, and referencing the parameters of the second parametric curve that has control points that are in the same positional relationship as the multiple control points rounded onto the grid.

2. A data processing method according to claim 1, wherein the parameters determined from the curve are the positions of multiple points on the second parametric curve and parameters corresponding to the multiple points, and the information used in image processing of the circuit pattern is the intersection of the boundaries of rectangular partitioned areas obtained by dividing an object to be irradiated with a charged particle beam into predetermined sizes with the first parametric curve.

3. A data processing method according to claim 2, wherein the parameters of the intersection point are calculated by interpolation using parameters corresponding to two points on the reference second parametric curve that are close to the boundary line of the partitioned area.

4. The data processing method according to claim 3, wherein the intersections are used to calculate a coverage of the circuit pattern in the partitioned area.

5. A data processing method according to claim 1, wherein the parameter determined from the curve is the position of the center of gravity of the area surrounded by the line segment connecting the start point and end point of the first parametric curve and the second parametric curve, and the information used in image processing of the circuit pattern is the position of the center of gravity of the area surrounded by the line segment connecting the start point and end point of the first parametric curve and the first parametric curve.

6. A data processing method according to claim 1, wherein the parameter determined from the curve is the area of ​​the region enclosed by the line segment connecting the start point and end point and the second parametric curve, and the information used in image processing of the circuit pattern is the area of ​​the region enclosed by the line segment connecting the start point and end point of the first parametric curve and the first parametric curve.

7. A data processing method according to claim 1, wherein the parameter determined from the curve is the curvature of a second parametric curve, and the information used in image processing of the circuit pattern is the curvature of the first parametric curve.

8. The data processing method according to claim 1, wherein the first parametric curve is generated by dividing a parametric curve that expresses the shape of the circuit pattern at positions of extrema and inflection points.

9. The data processing method of claim 1, wherein the first parametric curve and the second parametric curve are Bezier curves.

10. The data processing method according to claim 1, wherein the circuit pattern is a semiconductor circuit pattern.

11. A computer-readable recording medium having recorded thereon a program for causing a computer to execute the steps of: rounding the positions of a plurality of control points of a first parametric curve that represents the shape of a circuit pattern onto a grid at a predetermined interval; searching a table that defines the positions of the control points and parameters determined from the curve for each of a plurality of second parametric curves, and referring to the positions and corresponding parameters of the plurality of points of a second parametric curve that has control points that have the same positional relationship as the plurality of control points rounded onto the grid, and calculating information to be used in image processing of the circuit pattern.

12. A charged particle beam irradiation device comprising: an irradiation unit that irradiates an object with a charged particle beam; a memory unit that stores a table in which, for each of a plurality of second parametric curves, the positions of the control points and parameters calculated from the curve are defined; and a control unit that rounds the positions of the plurality of control points of a first parametric curve that represents the shape of a circuit pattern onto a grid with a predetermined interval, searches the table, refers to the positions of the plurality of points and corresponding parameters of a second parametric curve that has control points that have the same positional relationship as the plurality of control points rounded onto the grid, calculates information to be used for image processing of the circuit pattern, and controls the irradiation unit using the calculated information.

13. The charged particle beam irradiation device described in claim 12, wherein the memory unit stores a plurality of tables each having a different number of points on the second parametric curve, and the control unit switches the table to be searched based on the required accuracy of the circuit pattern.

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