Charged particle beam drawing method, charged particle beam drawing device, and program

Abstract

To correct a beam irradiation position with high accuracy and prevent deterioration of writing accuracy.SOLUTION: A charged particle beam writing method of deflecting a charged particle beam with a deflector and irradiating a substrate with the charged particle beam to draw a pattern includes calculating a charge amount distribution on the basis of the charge amount in a beam irradiation region on the substrate immediately after the charged particle beam is irradiated and a charge diffusion coefficient in the substrate, calculating a positional deviation amount distribution of the charged particle beam on the substrate on the basis of the charge distribution, and correcting the irradiation position of the charged particle beam on the basis of the positional deviation amount distribution.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a charged particle beam drawing method, a charged particle beam drawing apparatus, and a program. [Background technology]

[0002] As LSIs become more highly integrated, the circuit line width required for semiconductor devices is becoming finer every year. To form the desired circuit pattern on a semiconductor device, a method is adopted in which a high-precision original pattern (called a mask, or a reticle, especially when used in steppers and scanners) formed on quartz is reduced and transferred onto a wafer using a reduction projection exposure system. The high-precision original pattern is drawn using an electron beam drawing system, using so-called electron beam lithography technology.

[0003] When an electron beam is irradiated onto a substrate such as a mask, the irradiation position and its surroundings can become charged by previous electron beam irradiation, causing the irradiation position to shift. One conventional method for eliminating this beam irradiation position shift is to form an anti-static film on the substrate to prevent charging of the substrate surface. However, this anti-static film can affect the chemically amplified resist coated on the substrate, causing pattern defects or affecting the uniformity of pattern dimensions, and the anti-static film that can be used is often limited by its compatibility with the resist.

[0004] Depending on the type of antistatic film, a sufficient charge removal effect may not be obtained, and there is a problem in that the beam irradiation position may be shifted due to the charging effect caused by charges that have not been completely removed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-183098 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-158167 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-250286 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a charged particle beam drawing method, a charged particle beam drawing apparatus, and a program that can accurately correct the beam irradiation position and prevent a decrease in drawing accuracy. [Means for solving the problem]

[0007] A charged particle beam lithography method according to one aspect of the present invention is a charged particle beam lithography method that deflects a charged particle beam using a deflector and irradiates a substrate with the charged particle beam to draw a pattern, the method comprising: calculating a charge amount distribution based on the charge amount of a beam-irradiated region on the substrate immediately after irradiation with the charged particle beam and a diffusion coefficient of charge in the substrate; calculating a positional deviation amount distribution of the charged particle beam on the substrate based on the charge distribution; and correcting the irradiation position of the charged particle beam based on the positional deviation amount distribution.

[0008] A charged particle beam drawing apparatus according to one aspect of the present invention includes an emission unit that emits a charged particle beam, a deflector that deflects the emitted charged particle beam, a stage that supports a substrate onto which the charged particle beam is irradiated and a pattern is drawn, a charge amount calculation unit that calculates an amount of charge in a beam-irradiated region of the substrate immediately after irradiation with the charged particle beam and calculates a charge amount distribution based on the amount of charge and a diffusion coefficient of charge in the substrate, a positional deviation amount calculation unit that calculates a positional deviation amount distribution of the charged particle beam on the substrate based on the charge amount distribution, and a correction unit that corrects the irradiation position of the charged particle beam based on the positional deviation amount distribution.

[0009] A program according to one aspect of the present invention causes a computer that controls a charged particle beam drawing apparatus that deflects a charged particle beam using a deflector and irradiates a substrate with the charged particle beam to draw a pattern to execute the following steps: calculating a charge amount distribution based on the charge amount immediately after irradiating the charged particle beam and the diffusion coefficient of charge in the substrate; calculating a positional deviation amount distribution of the charged particle beam on the substrate based on the charge amount distribution; and correcting the irradiation position of the charged particle beam based on the positional deviation amount distribution. [Effects of the Invention]

[0010] According to the present invention, the beam irradiation position can be corrected with high precision, and a decrease in drawing precision can be prevented. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram of a drawing apparatus according to an embodiment of the present invention. [Figure 2] FIG. 10 is a diagram illustrating the state of stage movement. [Figure 3] FIG. 1 is a schematic diagram showing diffusion of charges in a planar direction on a substrate surface. [Figure 4] FIG. 10 is a diagram illustrating an example of a drawing layout. [Figure 5] FIG. 5 is a diagram showing an evaluation result of the amount of misalignment when the layout of FIG. 4 is drawn. [Figure 6] 10 is a graph showing the relationship between position accuracy and diffusion coefficient. [Figure 7] 10 is a graph showing the amount of positional deviation caused by a point charge. [Figure 8] FIG. 10 is a diagram showing the measurement results of the amount of positional deviation. [Figure 9] FIG. 10 is a diagram showing a simulation result of the amount of positional deviation. [Figure 10] 10 is a graph showing residuals obtained by correlating the measurement results of the amount of misalignment with the simulation results of the amount of misalignment for each diffusion coefficient. [Figure 11] 1 is a graph showing the optimum diffusion coefficient for each irradiation dose. [Figure 12] 10 is a graph showing the relationship between the amount of irradiation and the amount of charge immediately after irradiation. [Figure 13] 10 is a flowchart illustrating a drawing method according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[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 also be used.

[0013] FIG. 1 is a schematic diagram of a lithography apparatus according to an embodiment. The lithography apparatus 100 shown in FIG. 1 includes a lithography unit W and a control unit C. The lithography apparatus 100 is an example of an electron beam lithography apparatus. The lithography unit W includes an electron lens barrel 1 and a lithography chamber 14. Inside the electron lens barrel 1, 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 deflector 13, and an electrostatic lens 15 are arranged.

[0014] An XY stage 3 is placed in the patterning chamber 14. A substrate 2 to be patterned is placed on the XY stage 3. The substrate 2 includes a photomask used for exposure in semiconductor manufacturing and a semiconductor wafer for forming a semiconductor device. The photomask to be patterned also includes a mask blank on which nothing has yet been patterned. For example, the substrate 2 has quartz, a chrome film provided on the quartz, a resist layer provided on the chrome film, and an antistatic film provided on the resist layer. A mirror 4 for measuring the stage position is placed on the XY stage 3 at a position different from the position where the substrate 2 is placed.

[0015] A calibration mark M is provided on the XY stage 3 at a position different from the position where the substrate 2 is placed. For example, the mark M is a metal cross shape, and 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, adjustment of the deflection shape correction coefficient, etc.

[0016] 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 magnetic disk devices. The deflection control circuit 130 is connected to the shaping deflector 10 and the objective deflector 13.

[0017] The control computer 110 has the functions of a writing control unit 30 that controls the entire apparatus, a pattern density distribution calculation unit 32, a dose amount distribution calculation unit 34, a charge amount distribution calculation unit 36, and a positional deviation amount distribution calculation unit 38. Each unit of the control computer 110 may be configured by hardware including an electric circuit, a computer with a CPU, a circuit board, a quantum circuit, or a semiconductor device, or may be configured by software. Input data and calculation results of each unit of the control computer 110 are stored in a memory 142.

[0018] The control computer 120 has the functions of a shot data generation unit 41 and a positional deviation correction unit 42. The shot data generation unit 41 and the positional deviation correction unit 42 may be configured as software or hardware.

[0019] The deflection control circuit 130 has the functions of a shaping deflector control unit 43 and an objective deflector control unit 44. The shaping deflector control unit 43 and the objective deflector control unit 44 may be configured by software or hardware.

[0020] The storage device 140 stores drawing data (layout data) that defines a plurality of graphic patterns to be drawn.

[0021] An electron beam 6 emitted from an electron gun 5 (emitter) illuminates the entire first aperture plate 8, which has a rectangular hole, via an illumination lens 7. Here, the electron beam 6 is first shaped into a rectangle. After passing through the first aperture plate 8, the electron beam 6 as a first aperture image is projected onto a second aperture plate 11 by a projection lens 9. The position of the first aperture image on the second aperture plate 11 is deflected by a shaping deflector 10 controlled by a shaping deflector control unit 43, making it possible to change the beam shape and dimensions (variable shaping).

[0022] The electron beam 6 of the second aperture image that has passed through the second aperture plate 11 is focused by the objective lens 12, deflected by, for example, an electrostatic deflector (objective deflector 13) controlled by an objective deflector control unit 44, and irradiated onto a desired position on the substrate 2 on a movably arranged XY stage 3. The XY stage 3 is driven and controlled by a stage control unit 46. The position of the XY stage 3 is detected by a stage position detection unit 45. The stage position detection unit 45 includes, for example, a laser length measurement device that irradiates the mirror 4 with a laser and measures the position based on the interference between the incident light and the reflected light. The electrostatic lens 15 dynamically corrects the focal position of the electron beam 6 in accordance with unevenness on the surface of the substrate 2 (dynamic focus).

[0023] FIG. 2 is a diagram for explaining how the stage moves. When drawing on the substrate 2, the XY stage 3 is moved continuously in, for example, the X direction. The drawing area is virtually divided into a plurality of rectangular stripe regions (SR) by the deflectable width of the electron beam 6. The drawing process is performed in stripe region units. The movement of the XY stage 3 in the X direction is, for example, continuous, and at the same time, the shot position of the electron beam 6 is made to follow the stage movement. Continuous movement can shorten the drawing time.

[0024] After writing one stripe area, the XY stage 3 is stepped in the Y direction and the next stripe area is written in the X direction (reverse direction). By writing each stripe area in a zigzag pattern, the movement time of the XY stage 3 can be shortened.

[0025] When processing layout data (writing data), the writing device 100 virtually divides the writing area into a plurality of rectangular frame areas, and data processing is performed for each frame area. When multiple exposure is not performed, the frame area and the stripe area are usually the same area. When multiple exposure is performed, the frame area and the stripe area are shifted depending on the degree of multiplicity. In this way, the writing area of ​​the substrate 2 is virtually divided into a plurality of frame areas (stripe areas) that serve as writing unit areas, and the writing unit W writes for each frame area (stripe area).

[0026] It is known that when an electron beam is irradiated onto a substrate 2, the beam irradiation position shifts due to the resist charging effect. Conventionally, the position shift due to the resist charging effect has been predicted and corrected using charging effect correction from pattern data. However, depending on the type of anti-static film provided on the substrate 2, the position shift cannot be sufficiently corrected, and under certain conditions, the accuracy of the beam irradiation position may deteriorate.

[0027] When an electron beam is irradiated onto a substrate, the surface charge diffuses in the planar direction on the antistatic film, as shown in Figure 3. The inventors have found that if the sheet resistance of the antistatic film is not sufficiently low, the diffusion of charge is significantly slower than the progress speed of writing, and the charge accumulated on the antistatic film deflects the beam, affecting the beam irradiation position.

[0028] In this embodiment, the charge amount distribution is calculated taking into consideration the time-dependent diffusion of charge in the planar direction, and the positional deviation distribution of the electron beam is calculated based on the charge amount distribution, and the beam irradiation position is corrected.

[0029] Figure 4 shows an example of a lithography layout used to evaluate the effect of charge diffusion coefficients on position accuracy. A 0.5 μm, 8 μm-sized cross-shaped grid pattern for position measurement is arranged in 29 × 29 locations with a 5 mm pitch in a 140 mm × 140 mm area. To evaluate the surface charging effect, a 100% area-density high-dose area is located in the center of the layout in a 100 mm × 120 mm area. Within the high-dose area, a sufficiently small area (e.g., 16 μm × 16 μm) is hollowed out to prevent overlap between the position measurement grid and the high-dose area pattern. The grid pattern is drawn in order from the edge of the layout in the -Y direction to the +Y direction, and the high-dose area pattern and the grid pattern are drawn within the same frame area and merged.

[0030] Figure 5 shows the layout of Figure 4 with a high dose area at a dose of 30 μC / cm 2 The following shows an example of the evaluation results of the amount of misalignment of the grid pattern at different diffusion coefficients when writing with a stage speed of 50 mm / sec and a stripe area width of 81 μm. In each result, the amount of charge immediately after the beam irradiation (immediately after irradiation: the point when beam irradiation at a specified irradiation amount is completed) is the same, but when the diffusion coefficient is 0.1 mm 2 / sec, 0.3mm 2 / sec, 0.5mm 2 / sec, 1.0mm 2 / sec. The relationship between the positional accuracy 3s and the diffusion coefficient obtained from these evaluation results is shown in Figure 6. As shown in these examples, a large diffusion coefficient results in good positional accuracy, but a small diffusion coefficient results in large positional errors due to residual static electricity removal.

[0031] In this embodiment, when calculating the charge amount distribution, charge amount information Q(d) indicating the relationship between the charge amount Q of the irradiated area immediately after beam irradiation and the irradiation amount d, and the diffusion coefficient D of the charge (electrons) are obtained in advance.

[0032] To obtain charge amount information and charge diffusion coefficient, first, a test layout is drawn. For example, multiple layouts with different beam irradiation amounts for the high irradiation area pattern are drawn using a graphic arrangement similar to that of the layout in Figure 4, and the position error for each is obtained. To change the beam irradiation intensity for each layout, for example, layouts can be created in which the pattern density of the high irradiation area is changed to 3%, 5%, 10%, 15%, 20%, 25%, 50%, 75%, 100%, etc. The deviation from the design position of the grid pattern resulting from drawing each layout is measured using a position measuring device, and the position deviation distribution P meas (x i ,y i ,Q(d);D unknown ) is obtained. i is the number assigned to the box array on each grid of the test layout. Also, D unknown is the diffusion coefficient specific to the substrate and is determined by the procedure described below.

[0033] Next, the diffusion coefficient D is varied to multiple values ​​for the drawing data of this test layout, and the charge distribution C(x, y, t) at each time t is simulated. The drawing area is divided into drawing blocks of a certain mesh size L. The charge amount after the 0th to jth drawing blocks are drawn is calculated as the analytical solution of the two-dimensional diffusion equation using the following equations (1) to (3). In the following equations, t k is the time when the kth drawing interval is drawn, and (x k ,y k ) is the position of the kth drawing interval.

[0034]

number

[0035] The calculated charge distribution of the test layout at each time is convolved with the assumed response function r(x,y) to calculate the positional deviation from the charge distribution, and the simulation result P of the positional deviation distribution of the test layout with the diffusion coefficient D is obtained. sim (x i ,y i, Q(d);D) is calculated. The response function r(x, y) is a function that represents the relationship between the distance from the point charge to the desired drawing point and the amount of positional deviation, as shown in FIG.

[0036] Figure 8 shows the measurement results meas (x i ,y i ,Q(d);D unknown ) is shown. Also, Fig. 9 shows an example of Q = 1 (nC / cm) at a certain diffusion coefficient. 2 ) Simulation results P sim (x i ,y i , Q=1nC / cm 2 ,D=0.5mm 2 / sec).

[0037] The positional deviation distribution P obtained from the drawing results of these test layouts meas (x i ,y i ,Q(d);D unknown ) and the simulation result P sim (x i ,y i ,Q=1,D), and the diffusion coefficient D that minimizes the residual is determined as the optimal diffusion coefficient. The amount of charge immediately after irradiation is determined from the correlation slope (correlation coefficient) Q at that time. For example, Q=1[nC / cm 2 ] is used as a reference for the positional deviation simulation result, and by checking how many times the positional deviation of the drawing result is, the charge amount can be determined. If the correlation coefficient is 3, the charge amount immediately after irradiation is 3 [nC / cm 2 ].

[0038] Figure 10 shows the positional deviation distribution P meas (x i ,y i ,Q(d);D unknown ) and the simulation result P sim (x i ,y i ,Q=1,D) is shown below. In this example, the optimum diffusion coefficient is 0.5. Also, P meas =Q Psim The charge amount immediately after irradiation and writing can be calculated using the correlation coefficient Q that satisfies the following equation.

[0039] The above analysis is performed on the positional deviation distribution P obtained from the drawing results of multiple irradiation dose conditions during test layout drawing. meas (x i ,y i ,Q(d);D unknown ) are similarly performed for each of the conditions. As shown in FIG. 11, the diffusion coefficient D is calculated for each irradiation dose condition. For example, the average of these is used as the optimal diffusion coefficient D opt This optimum diffusion coefficient D opt is stored in the storage device 21 as the diffusion coefficient D.

[0040] 12, the charge amount Q(d) immediately after irradiation is determined for each irradiation amount condition. Information indicating the correspondence between this irradiation amount condition and the charge amount Q(d) is registered in the storage device 21 as charge amount information.

[0041] A writing method using a writing device in which charge amount information and diffusion coefficients are stored in the storage device 21 will be described with reference to the flowchart shown in Fig. 13. This writing method includes a pattern area density distribution calculation step (step S100), a dose amount distribution calculation step (step S102), a charge amount distribution calculation step (step S104), a position deviation amount distribution calculation step (step S106), a deflection position correction step (step S108), and a writing step (step S110).

[0042] In the pattern area density distribution calculation step (step S100), the pattern density distribution calculation unit 32 reads out the drawing data from the storage device 140, virtually divides the drawing area (or frame area) into a mesh of predetermined dimensions (grid dimensions), and calculates the pattern density, which indicates the arrangement ratio of the figure pattern defined in the drawing data, for each mesh area. Then, the distribution of the pattern density p for each mesh area is created.

[0043] In the dose distribution calculation step (step S102), the dose distribution calculation unit 34 (irradiation dose calculation unit) calculates the distribution of the dose d for each mesh region using the pattern density distribution. The dose d can be calculated by the following formula (4). In the following formula, η is the backscattering coefficient, d 100 is the reference dose (the dose when the pattern density is 100%). The irradiation dose can be calculated by multiplying the dose by the pattern density.

[0044] d=d 100 *{(1 / 2+η) / (1 / 2+η*p)} ···(4)

[0045] In the charge amount distribution calculation step (step S104), the charge amount distribution calculation unit 36 ​​reads out the charge amount information and the diffusion coefficient D from the storage device 21, and calculates the charge amount Q of the irradiated region immediately after irradiation from the irradiation amount calculated in step S102 by referring to the charge amount information. Then, the charge amount distribution calculation unit 36 ​​calculates the charge amount distribution by finding the charge amount for each mesh region using the calculated charge amount Q and the read diffusion coefficient D using the above formulas (1) to (3).

[0046] In the positional deviation amount distribution calculation step (step S106), the positional deviation amount distribution calculation unit 38 (positional deviation amount calculation unit) calculates the positional deviation amount based on the charge amount distribution. Specifically, the positional deviation amount distribution calculation unit 38 calculates the positional deviation amount of the writing position caused by the charge amount at each position of the charge amount distribution by convolving the charge amount distribution calculated in step S104 with the response function r(x, y). (x, y) indicates the beam irradiation position of the corresponding frame area currently undergoing data processing.

[0047] Then, the positional deviation amount distribution calculation unit 38 creates a positional deviation amount distribution from the positional deviation amount at each position (x, y) to be drawn in the corresponding frame area. The created positional deviation amount distribution is output to the control computer 120.

[0048] In the control computer 120, the shot data generation unit 41 reads the drawing data from the storage device 140 and performs multiple stages of data conversion processing to generate shot data in a format specific to the drawing apparatus 100. The size of a figure pattern defined in the drawing data is usually larger than the shot size that the drawing apparatus 100 can form in one shot. Therefore, in the drawing apparatus 100, each figure pattern is divided into multiple shot figures (shot division) so that the size is such that the drawing apparatus 100 can form in one shot. Then, for each shot figure, data such as a figure code indicating the figure type, coordinates, and size are defined as shot data.

[0049] In the deflection position correction step (step S108) (positional deviation correction step), the positional deviation correction unit 42 corrects the irradiation position using the positional deviation amount calculated in step S106. Here, the shot data for each position is corrected. Specifically, a correction value for correcting the positional deviation amount indicated by the positional deviation amount distribution is added to each position (x, y) of the shot data. For example, it is preferable to use a value obtained by reversing the positive and negative signs of the positional deviation amount indicated by the positional deviation amount distribution as the correction value. As a result, when the electron beam 6 is irradiated, the coordinates of the irradiation destination are corrected, and therefore the deflection position deflected by the objective deflector 13 is corrected. The shot data is defined in the data file so as to be arranged in shot order.

[0050] In the writing process (step S110), in the deflection control circuit 130, the shaping deflector control unit 43 calculates, in shot order, the deflection amount of the shaping deflector 10 for variably shaping the electron beam 6 based on the figure type and size defined in the shot data for each shot figure. The objective deflector control unit 44 also calculates the deflection amount of the objective deflector 13 for deflecting the shot figure to a position on the substrate 2 where the shot figure is to be irradiated. In other words, the objective deflector control unit 44 (deflection amount calculation unit) calculates the deflection amount for deflecting the electron beam to the corrected irradiation position. Then, the objective deflector 13 arranged in the electron lens barrel 1 deflects the electron beam according to the calculated deflection amount, thereby irradiating the electron beam to the corrected irradiation position. In this way, the writing unit W writes a pattern at the charge-corrected position on the substrate 2.

[0051] In this manner, in this embodiment, the amount of deviation of the beam irradiation position is calculated from the charge distribution of electrons diffusing slowly on the substrate surface, so that the beam irradiation position can be corrected with high precision.

[0052] As shown in Figure 3, when an electron beam is irradiated onto a substrate, holes (positive holes) generated due to the emission of secondary electrons accumulate in the resist layer and are gradually attenuated as they are absorbed by the light-shielding film. Because the resist layer is an insulator, the holes do not move in the planar direction, and charging occurs at the beam irradiated point. The irradiation position may be corrected by further considering the direct charge distribution at the beam irradiated point.

[0053] Furthermore, depending on the composition of the antistatic film, holes (positive holes) generated by the emission of secondary electrons may not be conducted to the resist layer, which is generally considered an insulator, but may diffuse and move on the antistatic film in the same way as electrons. In this case, the diffusion of holes may also be taken into account when predicting the charge distribution and correcting the irradiation position, and the above formulas (1) to (3) can be replaced by formulas (5) to (9) using analytical solutions of diffusion equations with two different diffusion coefficients Dn and Dp, as follows:

[0054] In the following formula, Dn represents the diffusion coefficient of electrons on the antistatic film, Dp represents the diffusion coefficient of holes on the antistatic film, Qn represents the charge amount immediately after irradiation caused by electrons due to beam irradiation, and Qp represents the charge amount immediately after irradiation caused by holes generated by beam irradiation.

[0055]

number

[0056] The charge amount may be predicted and the irradiation position may be corrected taking into account two or more such diffusions.

[0057] The effect of correcting the irradiation position based on the charge distribution that takes the diffusion coefficient into account depends on the magnitude relationship between the "writing progress speed" and the diffusion coefficient D. The "writing progress speed" can be defined as the "area of ​​the writing region" divided by the "writing time", for example, the "total area of ​​the writing region" divided by the "total writing time".

[0058] If the diffusion coefficient D is sufficiently smaller than the writing progress speed, the diffusion phenomenon of charge during writing can be ignored, and correction that takes the diffusion coefficient D into account is unnecessary. On the other hand, if the diffusion coefficient D is sufficiently larger than the writing progress speed, position errors due to charge resulting from residual static elimination and the like are reduced, and correction that takes the charging effect into account is therefore unnecessary. In other words, in consideration of the effect of correction, this embodiment is preferably applied when the diffusion coefficient D is within a predetermined range with respect to the writing progress speed, and this range can be, for example, 1% or more and 1000% or less of the writing progress speed.

[0059] Misalignment of the irradiation position due to charging phenomena is not limited to electron beam lithography systems, but the present invention can be applied to any charged particle beam system that uses the results obtained by irradiating a targeted position with a charged particle beam, such as an inspection system that inspects patterns with a charged particle beam such as an electron beam.

[0060] In the above embodiment, in order to reduce the effect of fogging caused by electrons scattered within the drawing chamber falling onto the substrate, a positive potential may be applied to the lower surface of the objective lens 12 (objective optical system) to prevent secondary electrons from being returned to the substrate surface.

[0061] The present invention is not limited to the above-described embodiments, and the components can be modified and embodied in practice without departing from the spirit of the invention. Furthermore, various inventions can be created by appropriately combining multiple components disclosed in the above-described embodiments. For example, some components may be omitted from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined. [Explanation of symbols]

[0062] 1 Electron telescope 2 boards 3 XY stage 4. Mirror 5. Electron gun 6. Electron Beam 7 Lighting lens 8 First Aperture Plate 9 Projection Lens 10 Deflector 11 Second aperture plate 12 Objective Lens 13 Deflector 14 Drawing room 15 Electrostatic Lens 21,140 Storage device 30 Drawing control unit 32 Pattern density distribution calculation unit 34 Dose distribution calculation section 36 Charge distribution calculation section 38 Position deviation amount distribution calculation unit 41 Shot data generation unit 42 Position deviation correction unit 43 Molding deflector control section 44 Objective deflector control section 45 Stage position detection unit 46 Stage control section 100 drawing device

Claims

1. 1. A charged particle beam writing method for writing a pattern by deflecting a charged particle beam using a deflector and irradiating a substrate with the charged particle beam, comprising: calculating a charge amount distribution based on the charge amount of a beam-irradiated region on the substrate immediately after irradiation with the charged particle beam and a diffusion coefficient of charge diffusing in a planar direction of the substrate on the substrate; calculating a positional deviation distribution of the charged particle beam on the substrate based on the charge amount distribution; a charged particle beam writing method for correcting the irradiation position of the charged particle beam based on the distribution of the positional deviation amount;

2. 2. The charged particle beam drawing method according to claim 1, wherein the diffusion coefficient is calculated based on a correlation between a positional deviation amount calculated from a preliminary drawing result and a positional deviation amount obtained for the charge amount distribution calculated by varying the diffusion coefficient.

3. 3. The charged particle beam writing method according to claim 1, wherein the writing area of ​​the substrate is virtually divided into sections of a predetermined mesh size, and the charge amount for each section is found as a solution of a diffusion equation from the charge amount immediately after irradiation of each section and the diffusion coefficient found in advance, thereby calculating the charge amount distribution.

4. an emission section that emits a charged particle beam; a deflector for deflecting the emitted charged particle beam; a stage on which a substrate is placed, the substrate being irradiated with the charged particle beam and on which a pattern is drawn; a charge amount calculation unit that calculates the amount of charge in a beam-irradiated region of the substrate immediately after irradiation with the charged particle beam, and calculates a charge amount distribution based on the amount of charge and a diffusion coefficient of charge diffusing in a planar direction of the substrate; a positional deviation amount calculation unit that calculates a positional deviation amount distribution of the charged particle beam on the substrate based on the charge amount distribution; a correction unit that corrects the irradiation position of the charged particle beam based on the positional deviation amount distribution; A charged particle beam writing apparatus comprising:

5. a computer that controls a charged particle beam lithography apparatus that deflects a charged particle beam by a deflector and irradiates a substrate with the charged particle beam to draw a pattern; calculating a charge amount distribution based on the charge amount immediately after irradiation with the charged particle beam and a diffusion coefficient of the charge diffusing in the substrate in a planar direction of the substrate; calculating a positional deviation distribution of the charged particle beam on the substrate based on the charge amount distribution; correcting the irradiation position of the charged particle beam based on the positional deviation distribution; A program characterized by executing the following.

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