Methods, apparatus, and computer-readable recording media for depicting charged particle beams

Abstract

This embodiment provides a charged particle beam mapping method, a charged particle beam mapping apparatus, and a computer-readable recording medium that can prevent degradation of mapping accuracy by accurately correcting the beam irradiation position. The charged particle beam mapping method of this embodiment deflects a charged particle beam using a deflector and irradiates the substrate with the charged particle beam to map a pattern. This method calculates the charge distribution based on the charge of the irradiated area on the substrate immediately after irradiation and the charge diffusion coefficient in the substrate; calculates the position offset distribution of the charged particle beam on the substrate based on the charge distribution; and corrects the irradiation position of the charged particle beam based on the position offset distribution.

Description

[0001] [Related Application]

[0002] This application enjoys priority to Japanese Patent Application No. 2021-084008 (filed on May 18, 2021) and Japanese Patent Application No. 2022-067706 (filed on April 15, 2022). This application incorporates all contents of the basic applications by reference. Technical Field

[0003] This invention relates to a method for depicting charged particle beams, an apparatus for depicting charged particle beams, and a computer-readable recording medium. Background Technology

[0004] With the increasing integration of LSIs, the required linewidths of semiconductor devices are becoming smaller year by year. To form the desired circuit pattern on a semiconductor device, the following method is used: a high-precision original pattern (mask, or especially the pattern used in steppers or scanners, also called an intermediate mask) formed on quartz is reduced and transferred onto the wafer using a reduction projection exposure device. The high-precision original pattern is drawn by an electron beam lithography device using what is known as electron beam lithography.

[0005] When a substrate such as a mask is irradiated with an electron beam, the irradiated location or its surroundings become charged due to the previous electron beam irradiation, causing the irradiation location to shift. Conventionally, one method to eliminate this shift in irradiation location is to form a charge-preventing film on the substrate to prevent charging of the substrate surface. However, this charge-preventing film can affect the chemical amplification resist applied to the substrate, sometimes becoming a pattern defect or affecting the uniformity of pattern dimensions. Sometimes, the compatibility of the charge-preventing film with the resist limits its usability.

[0006] Depending on the type of anti-charge film, sufficient charge removal effect cannot be obtained, and there is a problem of beam irradiation position deviation caused by the charge effect due to incomplete charge removal. Summary of the Invention

[0007] This embodiment provides a charged particle beam mapping method, a charged particle beam mapping apparatus, and a computer-readable recording medium that can prevent a reduction in mapping accuracy by accurately correcting the beam irradiation position.

[0008] The charged particle beam drawing method of this embodiment deflects the charged particle beam using a deflector and irradiates the substrate with the charged particle beam to draw a pattern. This charged particle beam drawing method calculates the charge distribution based on the charge of the irradiated area on the substrate immediately after irradiation and the charge diffusion coefficient in the substrate; calculates the position offset distribution of the charged particle beam on the substrate based on the charge distribution; and corrects the irradiation position of the charged particle beam based on the position offset distribution. Attached Figure Description

[0009] Figure 1 This is a schematic diagram depicting an embodiment of the apparatus of the present invention.

[0010] Figure 2 This is a diagram illustrating the movement of the workbench.

[0011] Figure 3 This is a schematic diagram illustrating the diffusion of charges in the planar direction on the surface of a substrate.

[0012] Figure 4 This is a diagram illustrating an example of a layout.

[0013] Figure 5 It means that it depicts Figure 4 The graph shows the evaluation results of the position offset under the given layout.

[0014] Figure 6 It is a graph showing the relationship between positional accuracy and diffusion coefficient.

[0015] Figure 7 It is a graph representing the position offset based on point charges.

[0016] Figure 8 This is a graph showing the measurement results of the position offset.

[0017] Figure 9 This is a graph representing the simulation results of the position offset.

[0018] Figure 10 It is a graph showing the residuals between the measured position offset and the simulated position offset for each diffusion coefficient.

[0019] Figure 11 It is a graph representing the optimal diffusion coefficient for each irradiation dose.

[0020] Figure 12 It is a graph showing the relationship between the amount of irradiation and the charge immediately after irradiation.

[0021] Figure 13 This is a flowchart illustrating the method of depicting this embodiment.

[0022] [Explanation of reference numerals in the attached figures]

[0023] 1: Electron microscope tube

[0024] 2: Substrate

[0025] 3: XY workbench

[0026] 4: Reflector

[0027] 5: Electron gun

[0028] 6: Electron Beam

[0029] 7: Illumination Lens

[0030] 8: First aperture plate

[0031] 9: Projection lens

[0032] 10: Deflector

[0033] 11: Second aperture plate

[0034] 12: Objective lens

[0035] 13: Deflector

[0036] 14: Drawing Room

[0037] 15: Electrostatic Lens

[0038] 21, 140: Storage devices

[0039] 30: Depicting the control unit

[0040] 32: Pattern Density Distribution Calculation Department

[0041] 34: Dose Distribution Calculation Unit

[0042] 36: Charge Distribution Calculation Department

[0043] 38: Position Offset Distribution Calculation Unit

[0044] 41: Transmission Data Generation Unit

[0045] 42: Position offset correction unit

[0046] 43: Forming Deflector Control Unit

[0047] 44: Objective lens deflector control unit

[0048] 45: Workbench Position Detection Department

[0049] 46: Workbench Control Department

[0050] 100: Depicting device Detailed Implementation

[0051] Hereinafter, embodiments of the present invention will be described based on the accompanying drawings. In the embodiments, an electron beam structure will be described as an example of a charged particle beam. However, the charged particle beam is not limited to an electron beam, and may also be an ion beam, etc.

[0052] Figure 1 This is a schematic structural diagram of the apparatus depicting the implementation method. Figure 1 The depiction apparatus 100 shown includes a depiction unit W and a control unit C. The depiction apparatus 100 is an example of an electron beam depiction apparatus. The depiction unit W includes an electron tube 1 and a depiction chamber 14. Inside the electron tube 1 are arranged an electron gun 5, an illumination lens 7, a first aperture plate 8, a projection lens 9, a shaping deflector 10, a second aperture plate 11, an objective lens 12, an objective lens deflector 13, and an electrostatic lens 15.

[0053] An XY stage 3 is arranged inside the drawing chamber 14. A substrate 2, which is the object to be drawn, is arranged on the XY stage 3. The substrate 2 includes photomasks used in semiconductor manufacturing exposure, semiconductor wafers forming semiconductor devices, etc. In addition, the photomask to be drawn also includes a mask blank that is not drawn. For example, the substrate 2 has quartz, a chromium film provided on the quartz, a resist layer provided on the chromium film, and a charge prevention film provided on the resist layer. A stage position measuring mirror 4 is arranged on the XY stage 3 at a position different from the position where the substrate 2 is placed.

[0054] On the XY stage 3, a calibration mark M is set at a position different from that of the substrate 2. For example, the mark M is a metal cross shape. The mark M is scanned with an electron beam, and the reflected electrons from the mark M are detected by a detector (not shown) to perform focus adjustment, position adjustment, and deflection shape correction coefficient adjustment.

[0055] The control unit C includes control computers 110 and 120, a stage position detection unit 45, a stage control unit 46, a deflection control circuit 130, a memory 142, and storage devices 21 and 140 such as a disk drive. The deflection control circuit 130 is connected to the forming deflector 10 and the objective lens deflector 13.

[0056] The control computer 110 has functions including a drawing control unit 30 for overall device control, a pattern density distribution calculation unit 32, a dose distribution calculation unit 34, a charge distribution calculation unit 36, and a position offset distribution calculation unit 38. Each part of the control computer 110 can be constructed from hardware including circuits, a computer with a CPU, a circuit board, a quantum circuit, or a semiconductor device, or it can be constructed from software. The input data and calculation results of each part of the control computer 110 are stored in the memory 142.

[0057] The control computer 120 has the functions of a transmission data generation unit 41 and a position offset correction unit 42. The transmission data generation unit 41 and the position offset correction unit 42 can be configured in software or in hardware.

[0058] The deflection control circuit 130 has the functions of the shaping deflector control unit 43 and the objective lens deflector control unit 44. The shaping deflector control unit 43 and the objective lens deflector control unit 44 can be configured in software or in hardware.

[0059] The storage device 140 stores drawing data (layout data) that defines the multiple graphic patterns being drawn.

[0060] The electron beam 6 emitted from the electron gun 5 (emission section) illuminates the entire first aperture plate 8, which has a rectangular aperture, through the illumination lens 7. Here, the electron beam 6 is first shaped into a rectangle. The electron beam 6, after passing through the first aperture plate 8, is projected onto the second aperture plate 11 by the projection lens 9. The position of the first aperture image on the second aperture plate 11 is deflected by the shaping deflector 10, which is controlled by the shaping deflector control unit 43, enabling the beam shape and size to be changed (variable shaping).

[0061] The electron beam 6, after passing through the second aperture plate 11, is focused by the objective lens 12 and deflected by an electrostatic deflector (objective lens deflector 13) controlled by the objective lens deflector control unit 44, illuminating the desired position of the substrate 2 on the movable XY stage 3. The XY stage 3 is driven and controlled by the stage control unit 46. The position of the XY stage 3 is detected by the stage position detection unit 45. The stage position detection unit 45 includes, for example, a laser length measuring device that irradiates the reflector 4 with laser light and determines the position based on the interference of the incident and reflected light. The electrostatic lens 15 dynamically corrects the focal position of the electron beam 6 (dynamic focusing) in accordance with the concavity and convexity of the substrate 2 surface.

[0062] Figure 2 This diagram illustrates the movement of the worktable. When drawing onto the substrate 2, the XY worktable 3 is moved continuously, for example, in the X direction. The drawing area is virtually divided into multiple elongated strip regions (SRs) with a deflectable width of the electron beam 6. The drawing process is performed on a strip region basis. The movement of the XY worktable 3 in the X direction is, for example, continuous, and the emission position of the electron beam 6 also follows the movement of the worktable. Continuous movement shortens the drawing time.

[0063] After depicting one strip region, the XY stage 3 is stepped and conveyed along the Y direction, and the depiction of the next strip region is performed in the X direction (reverse direction). By making the depiction of each strip region meander, the travel time of the XY stage 3 can be shortened.

[0064] In the drawing apparatus 100, when processing layout data (drawing data), the drawing area is virtually divided into multiple elongated frame regions, and data processing is performed on each frame region. Normally, without multiple exposures, the frame regions and strip regions are the same area. With multiple exposures, the frame regions and strip regions are staggered depending on the number of exposures. Thus, the drawing area of ​​the substrate 2 is virtually divided into frame regions (strip regions) that become multiple drawing unit regions, and the drawing unit W performs drawing on each frame region (strip region).

[0065] It is known that when an electron beam is irradiated onto substrate 2, the irradiation position shifts due to the resist's charging effect. Conventionally, position shifts caused by the resist's charging effect are predicted and corrected based on pattern data through charging effect correction. However, depending on the type of anti-charging film applied to substrate 2, the position shift cannot always be adequately corrected, leading to a deterioration in the accuracy of the irradiation position under certain conditions.

[0066] like Figure 3 As shown, when an electron beam irradiates the substrate, surface charge diffuses in a planar direction on the anti-charge film. The inventors have discovered that when the surface resistance of the anti-charge film is not sufficiently low, the diffusion of charge is significantly delayed relative to the depicted process, and the charge accumulated in the anti-charge film deflects the beam, affecting the beam irradiation position.

[0067] In this embodiment, the charge distribution is calculated by considering the time-dependent diffusion of charge in the planar direction, and the position offset distribution of the electron beam is calculated based on the charge distribution to correct the beam irradiation position.

[0068] Figure 4This is an example of a layout used to evaluate the difference in positional accuracy caused by variations in charge diffusion coefficients. A cross-shaped position-measuring grid pattern, 0.5 μm in size and 8 μm in dimensions, is arranged at 29 x 29 locations with a 5 mm spacing within a 140 mm x 140 mm area. Additionally, to evaluate the surface charging effect, a high-irradiation area with 100% area density is arranged in a 100 mm x 120 mm region at the center of the layout. Within the high-irradiation area, a sufficiently small region, for example, 16 μm x 16 μm, is carved out to ensure that the position-measuring grid and the high-irradiation area pattern do not overlap, and a frame-shaped position-measuring grid pattern is arranged there. As a drawing sequence, the grid pattern proceeds sequentially from the end of the layout in the -Y direction towards the +Y direction, with the high-irradiation area pattern and the grid pattern drawn and merged within the same frame area.

[0069] Figure 5 This indicates a dose of 30 μC / cm 2 Table speed 50 mm / s, strip area width 81 μm drawing Figure 4 Examples of evaluation results under different diffusion coefficients for high-irradiation areas of the layout, with varying grid pattern position offsets. In each result, the charge is the same immediately after beam irradiation (immediately after irradiation: the moment the beam irradiation at the specified irradiation level is completed), but the diffusion coefficient is the same for 0.1 mm. 2 / sec, 0.3mm 2 / sec, 0.5mm 2 / sec, 1.0mm 2 / sec differs. Furthermore, the relationship between the positional accuracy 3s and the diffusion coefficient, obtained from these evaluation results, is shown in... Figure 6 As these examples show, a larger diffusion coefficient leads to better positional accuracy, while a smaller diffusion coefficient results in greater positional errors due to residual charge.

[0070] In calculating the charge distribution, in this embodiment, the charge information Q(d) representing the relationship between the charge Q and the irradiation amount d in the irradiated area immediately after the beam is irradiated, and the diffusion coefficient D of the charge (electrons) are calculated in advance.

[0071] To determine the charge information and charge diffusion coefficient, the test layout is first described. For example, by comparing with... Figure 4Using the same graphic configuration, multiple layouts with varying beam irradiation intensities were depicted to represent patterns in high-irradiation areas, and their respective positional errors were calculated. To vary the beam irradiation intensity for each layout, for example, the pattern density in the high-irradiation area could be changed to 3%, 5%, 10%, 15%, 20%, 25%, 50%, 75%, 100%, etc. A position measuring device was used to measure the offset of the depicted layout from the designed position of the grid pattern, obtaining the positional offset distribution P. meas (x i y i , Q(d); D unknown ). i is the sequence number assigned to the box array on each grid of the test layout. Additionally, D unknown It is the diffusion coefficient unique to the substrate, which is determined through the steps described later.

[0072] Next, for the depiction data of this test layout, the diffusion coefficient D is varied to multiple values, and the charge distribution C(x, y, t) at each time t is simulated. The depiction area is divided into depiction partitions with a certain grid size L. The charge after depicting the 0th to jth depiction partitions is obtained as the analytical solution of the two-dimensional diffusion equation as shown in the following equations (1) to (3). In the following equations, t k It describes the moment of the k-th depicted partition, (x k y k ) is the position of the k-th depicted partition.

[0073]

[0074]

[0075]

[0076] For the calculated charge distribution of the test layout at each time step, convolution is used to calculate the simulated position offset distribution P of the test layout based on the diffusion coefficient D, assuming a response function r(x, y) to calculate the position offset based on the charge distribution. sim (x i y i , Q(d); D). The response function r(x, y) represents, for example, Figure 7 As shown, this is a function relating the distance from a point charge to the desired location to the position offset.

[0077] Figure 8 The measurement result P indicates meas (x i y i Q(d); D unknown One example. Additionally, Figure 9This indicates that Q = 1 (nC / cm) for a certain diffusion coefficient. 2 Simulation results P under ) sim (x i y i Q = 1nC / cm 2 D = 0.5 mm 2 / sec).

[0078] Obtain the position offset distribution P derived from the depiction results of these test layouts. meas (x i y i Q(d); D unknown ) and simulation results P sim (x i y i The optimal diffusion coefficient is determined by the correlation between Q = 1 and D, where the residual is minimized. Furthermore, the charge immediately after irradiation is determined based on the slope (correlation coefficient) Q of the correlation at this point. For example, with Q = 1 [nC / cm²]... 2 Using the positional offset simulation results as a benchmark, the charge can be determined by confirming whether the positional offset of the depicted results is several times that of the original simulation. When the correlation coefficient is 3, the charge immediately after irradiation is 3 [nC / cm²]. 2 ].

[0079] Figure 10 The position offset distribution P is shown. sim (x i y i Q(d); D unknown ) and simulation results P sim (x i y i This is an example of the residuals after the correlation between Q=1 and D). In this example, the diffusion coefficient of 0.5 is the optimal diffusion coefficient. Furthermore, by satisfying P at this point... meas =Q·P sim The correlation coefficient Q is used to calculate the charge after irradiation.

[0080] The position offset distribution P is obtained from the depiction results of multiple illumination conditions during the test layout depiction. meas (x i y i Q(d); D unknown Repeat the above analysis for each case. Figure 11 As shown, the diffusion coefficient D (first diffusion coefficient) is calculated for each irradiation condition. For example, their average is calculated as the optimal diffusion coefficient D. opt (Second diffusion coefficient). The optimal diffusion coefficient D... opt The diffusion coefficient D is stored in storage device 21.

[0081] In addition, such as Figure 12 As shown, for each irradiation condition, the charge Q(d) immediately after irradiation is calculated. The information representing the correspondence between the irradiation condition and the charge Q(d) is recorded as charge information in the storage device 21.

[0082] according to Figure 13 The flowchart shown illustrates a drawing method using a drawing device that stores charge information and diffusion coefficient in storage device 21. This drawing method includes a pattern area density distribution calculation step (step S100), a dose distribution calculation step (step S102), a charge distribution calculation step (step S104), a position offset distribution calculation step (step S106), a deflection position correction step (step S108), and a drawing step (step S110).

[0083] In the pattern area density distribution calculation process (step S100), the pattern density distribution calculation unit 32 reads the drawing data from the storage device 140, virtually divides the drawing area (or frame area) into a grid shape at a specified size (grid size), and calculates the pattern density representing the configuration ratio of the graphic pattern defined in the drawing data for each grid area. Then, the pattern density p distribution of each grid area is created.

[0084] In the dose distribution calculation process (step S102), the dose distribution calculation unit 34 (irradiation calculation unit) uses a pattern density distribution to calculate the dose d distribution for each grid region. The dose d can be calculated using the following equation (4). In the following equation, η is the backscattering coefficient, and d 100 This is the baseline dose (the dose at 100% pattern density). Then, the exposure dose is calculated by multiplying the dose by the pattern density.

[0085] d = d 100 *{(1 / 2+η) / (1 / 2+η*p)}...(4)

[0086] In the charge distribution calculation process (step S104), the charge distribution calculation unit 36 ​​reads the charge information and diffusion coefficient D from the storage device 21, and calculates the charge Q of the irradiated area immediately after irradiation based on the irradiation amount calculated in step S102, referring to the charge information. Then, the charge distribution calculation unit 36 ​​calculates the charge of each grid area using the above formulas (1) to (3) based on the calculated charge Q and the read diffusion coefficient D, thereby calculating the charge distribution.

[0087] In the position offset distribution calculation process (step S106), the position offset distribution calculation unit 38 (position offset calculation unit) calculates the position offset based on the charge distribution. Specifically, the position offset distribution calculation unit 38 calculates the position offset of the depicted position caused by the charge at each position of the charge distribution by using the convolution integral response function r(x, y) of the charge distribution calculated in step S104. (x, y) represents the beam illumination position of the corresponding frame region currently undergoing data processing.

[0088] Then, the position offset distribution calculation unit 38 generates a position offset distribution based on the position offsets of each position (x, y) to be depicted in the corresponding frame region. The generated position offset distribution is output to the control computer 120.

[0089] Within the control computer 120, the transmission data generation unit 41 reads the drawing data from the storage device 140, performs multi-level data transformation processing, and generates transmission data in a format inherent to the drawing device 100. The size of the graphic pattern defined in the drawing data is typically larger than the transmission size that the drawing device 100 can form in a single transmission. Therefore, within the drawing device 100, each graphic pattern is divided into multiple transmission patterns (transmission segments) in a manner that makes the size formable by the drawing device 100 in a single transmission. Then, for each transmission pattern, data such as the graphic code representing the graphic type, coordinates, and dimensions are defined as transmission data.

[0090] In the deflection position correction process (step S108) (position offset correction process), the position offset correction unit 42 uses the position offset calculated in step S106 to correct the irradiation position. Here, the emission data at each position is corrected. Specifically, a correction value is added to each position (x, y) of the emission data. This correction value is a value that corrects the position offset represented by the position offset distribution. For example, it is preferable to use a value that reverses the sign of the position offset represented by the position offset distribution. As a result, when irradiating the electron beam 6, the coordinates of its irradiation destination are corrected, and therefore the deflection position deflected by the objective lens deflector 13 is corrected. The emission data is defined as a data file in a manner arranged according to the emission sequence.

[0091] In the drawing process (step S110), within the deflection control circuit 130, according to the emission sequence, the forming deflector control unit 43 calculates the deflection amount of the forming deflector 10, which is used to shape the electron beam 6, for each emission pattern based on the pattern type and size defined in the emission data. Additionally, the objective lens deflector control unit 44 calculates the deflection amount of the objective lens deflector 13, which is used to deflect the emission pattern to the position on the substrate 2 to be irradiated. In other words, the objective lens deflector control unit 44 (deflection amount calculation unit) calculates the deflection amount that deflects the electron beam to the corrected irradiation position. Furthermore, the objective lens deflector 13, disposed within the electron microscope barrel 1, deflects the electron beam according to the calculated deflection amount, thereby irradiating the electron beam to the corrected irradiation position. Thus, the drawing unit W draws a pattern at the electrically corrected position on the substrate 2.

[0092] Thus, in this embodiment, the offset of the beam irradiation position is calculated based on the charge distribution of electrons that diffuse slowly across the substrate surface, thereby enabling high-precision correction of the beam irradiation position.

[0093] like Figure 3 As shown, when an electron beam is irradiated onto the substrate, holes generated from the emission of two electrons accumulate in the resist layer, are absorbed by the light-shielding film, and gradually decay. Since the resist layer is an insulator, the holes do not move in the planar direction, resulting in a charged area at the irradiated site. Further consideration can be given to the direct charge distribution at such irradiated sites to correct the irradiation position.

[0094] Furthermore, depending on the composition of the anti-charge film, holes (holes) sometimes generated due to the emission of electrons do not generally conduct electricity to the resist layer, which is considered an insulator, but diffuse and move on the anti-charge film in the same way as electrons. In this case, the diffusion of holes can be further considered to predict the charge distribution and correct the irradiation position. The above mathematical equations (1) to (3) are replaced as follows with equations (5) to (9) using analytical solutions of diffusion equations with two different diffusion coefficients Dn and Dp.

[0095] In the following formula, Dn represents the diffusion coefficient of electrons on the charged anti-electron membrane, Dp represents the diffusion coefficient of holes on the charged anti-electron membrane, Qn represents the charge immediately after irradiation caused by electrons based on beam irradiation, and Qp represents the charge immediately after irradiation caused by the generation of holes based on beam irradiation.

[0096]

[0097]

[0098]

[0099]

[0100]

[0101] It is also possible to predict the charge of two or more such diffusions and correct the irradiation position.

[0102] Furthermore, the effectiveness of correcting the irradiation position based on the charge distribution considering the diffusion coefficient depends on the relationship between the "drawing travel speed" and the diffusion coefficient D. The "drawing travel speed" can be defined by dividing the "area of ​​the drawn region" by the "drawing time," for example, by dividing the "total area of ​​the drawn region" by the "total drawing time."

[0103] If the diffusion coefficient D is smaller than the depicted travel speed, the diffusion of charge in the depiction can be ignored, and correction considering the diffusion coefficient D is unnecessary. On the other hand, if the diffusion coefficient D is sufficiently larger than the depicted travel speed, the positional error caused by charge residue, etc., becomes smaller, and therefore correction considering the charging effect is unnecessary. That is, considering the effect of correction, this embodiment is preferably applied when the diffusion coefficient D is within a predetermined range relative to the depicted travel speed, such that the range can be set to, for example, 1% or more and 1000% or less of the depicted travel speed.

[0104] The shift in irradiation position caused by the charging phenomenon is not limited to electron beam drawing devices. This invention can be applied to inspection devices that use charged particle beams such as electron beams to inspect patterns, and charged particle beam devices that use the result obtained by irradiating a target position with a charged particle beam.

[0105] In the above embodiment, in order to reduce the effect of the electrons scattered in the drawing chamber falling onto the substrate and becoming charged, a positive potential can also be applied to the lower surface of the objective lens 12 (objective lens optical system) so that the secondary electrons do not return to the substrate surface.

[0106] Furthermore, this invention is not limited to the embodiments described above. During implementation, the constituent elements can be modified and modified to be more specific without departing from its spirit. Additionally, various inventions can be formed by appropriately combining the multiple constituent elements disclosed in the above embodiments. For example, several constituent elements may be deleted from all the constituent elements shown in the embodiments. Furthermore, constituent elements from different embodiments may be appropriately combined.

Claims

1. A method for depicting a charged particle beam, comprising deflecting a charged particle beam using a deflector and irradiating the charged particle beam onto a substrate to depict a pattern, characterized in that... The charge distribution is calculated based on the charge of the beam-irradiated area on the substrate immediately after irradiation with the charged particle beam and the charge diffusion coefficient in the substrate. Based on the charge distribution, calculate the position offset distribution of the charged particle beam on the substrate; The irradiation position of the charged particle beam is corrected based on the position offset distribution.

2. The method for depicting charged particle beams according to claim 1, characterized in that, The diffusion coefficient is determined based on the correlation between the position offset obtained from the prior mapping results and the position offset relative to the charge distribution calculated by changing the diffusion coefficient.

3. The method for depicting charged particle beams according to claim 2, characterized in that, The pre-illumination results include the illustrations corresponding to each of the multiple illumination conditions. For each exposure condition, the first diffusion coefficient based on the aforementioned correlation is calculated. The average value of the first diffusion coefficient under each irradiation condition, i.e., the second diffusion coefficient, is used to calculate the charge distribution.

4. The method for depicting charged particle beams according to claim 1, characterized in that, The depicted area of ​​the substrate is virtually divided into partitions of a specified grid size. Based on the charge after each partition has been irradiated and the pre-calculated diffusion coefficient, the charge of each partition is calculated as a solution to the diffusion equation, and the charge distribution is calculated.

5. The method for depicting charged particle beams according to claim 1, characterized in that, The charge distribution is a distribution that takes into account two or more different diffusion coefficients.

6. A charged particle beam mapping device, comprising: The emission section emits a beam of charged particles. A deflector that deflects the emitted beam of charged particles; A worktable on which a substrate is irradiated by the charged particle beam and patterned is drawn; The charge calculation unit calculates the charge in the beam-irradiated area of ​​the substrate immediately after irradiation by the charged particle beam, and calculates the charge distribution based on the charge and the charge diffusion coefficient in the substrate. The position offset calculation unit calculates the position offset distribution of the charged particle beam on the substrate based on the charge distribution; and The correction unit corrects the irradiation position of the charged particle beam based on the position offset distribution.

7. The charged particle beam mapping device according to claim 6, characterized in that, The charge calculation unit virtually divides the depicted area of ​​the substrate into partitions of a predetermined grid size, and calculates the charge of each partition as a solution to the diffusion equation based on the charge after each partition has been irradiated and the pre-calculated diffusion coefficient, thereby calculating the charge distribution.

8. A computer-readable recording medium storing a program for causing a computer controlling a charged particle beam drawing apparatus to perform the following steps: the charged particle beam drawing apparatus deflects a charged particle beam via a deflector and illuminates the charged particle beam onto a substrate to draw a pattern, the steps comprising: The step of calculating the charge distribution based on the charge after being irradiated by the charged particle beam and the charge diffusion coefficient in the substrate; The steps of calculating the position offset distribution of the charged particle beam on the substrate based on the charge distribution; and The step of correcting the irradiation position of the charged particle beam based on the position offset distribution.

9. The computer-readable recording medium according to claim 8, characterized in that, The program causes the computer to operate in the following manner: virtually divide the depicted area of ​​the substrate into partitions of a specified grid size, calculate the charge of each partition as a solution to the diffusion equation based on the charge after each partition has been irradiated and the pre-calculated diffusion coefficient, and calculate the charge distribution.

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