Multi-charged particle beam lithography method and multi-charged particle beam lithography apparatus

Abstract

This provides a drawing method that can reduce the total amount of on-beam current that is turned on simultaneously. [Solution] The multi-charged particle beam drawing method of the present invention is characterized by comprising the steps of: assigning a plurality of groups of irradiation unit regions, which are unit regions to which each beam of the multi-charged particle beam is irradiated, such that the groups of irradiation unit regions in each set are different from each other, and that the plurality of irradiation unit regions irradiated by each shot of the multi-charged particle beam include irradiation unit regions of different groups; assigning a subshot that is pre-set according to the irradiation time set for the irradiation unit region or a value obtained based on the irradiation time, from among a plurality of subshots of a plurality of sub-irradiation times obtained by dividing the maximum irradiation time for one shot; and assigning a subshot to an irradiation unit region to which another group of the plurality of groups is assigned, which includes a subshot other than the subshot pre-set for one group of the same set.

Description

[Technical Field]

[0001] The present invention relates to a multi-charged particle beam lithography method and a multi-charged particle beam lithography apparatus. [Background technology]

[0002] Lithography technology, which drives the miniaturization of semiconductor devices, is an extremely important process in semiconductor manufacturing that is the only one to generate patterns. In recent years, with the increasing integration of LSIs, the circuit line width required for semiconductor devices has been getting smaller year by year. Electron beam lithography technology inherently possesses excellent resolution, and is used to draw patterns on wafer masks and wafers for wafer exposure.

[0003] For example, there are lithography systems that use multiple electron beams. Compared to lithography with a single electron beam, using multiple electron beams allows for the irradiation of many beams at once, significantly improving throughput. In such a multi-beam lithography system, for example, the electron beam emitted from the electron gun is passed through a mask with multiple holes to form multiple beams. Each beam is then blanked, and the unshielded beams are reduced by an optical system, deflected by a deflector, and irradiated to the desired position on the sample.

[0004] With the recent miniaturization of patterns, the lithography process is shifting to low-sensitivity resists. As resists become less sensitive, a higher dose of irradiation is required. To achieve a high dose of irradiation without increasing the lithography time, it is necessary to increase the number of beams and current density used in multi-beam lithography to increase the total beam current. However, in multi-beam lithography, increasing the total beam current leads to beam blurring due to the Coulomb effect, resulting in a deterioration of resolution performance.

[0005] Therefore, it is desirable to reduce the number of beams that are turned on simultaneously in order to lower the average on-beam current during the shot cycle.

[0006] Here, it is disclosed that the maximum configurable irradiation time per shot is divided into multiple split shots of multiple irradiation times, and shots for each pixel's irradiation time are performed by combining these split shots (see Patent Document 1). It is also disclosed that the multi-beam is divided into multiple groups, and the total beam current at the same timing is reduced by staggering the irradiation times for each group. In such cases, it is necessary to perform one shot twice with a time difference. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2017-191900 [Overview of the project] [Problems that the invention aims to solve]

[0008] One aspect of the present invention provides a drawing method and a drawing apparatus capable of reducing the total amount of on-beam current that is turned on simultaneously. [Means for solving the problem]

[0009] One embodiment of the present invention is a multi-charged particle beam lithography method, The drawing area of ​​the sample is divided into multiple irradiation unit regions, each of which is irradiated by a multi-charged particle beam, and multiple sets of two or more irradiation unit regions are pre-set. For each irradiation unit region of the multiple irradiation unit regions, one group is assigned such that the irradiation unit regions within each set belong to different groups, and the multiple irradiation unit regions irradiated by each shot of the multi-charged particle beam belong to different groups. For each irradiation unit area, for an irradiation unit area to which one of the multiple groups is assigned, the process of assigning a subshot that is pre-set according to the irradiation time set for that irradiation unit area or a value determined based on the irradiation time, from among multiple subshots with multiple sub-irradiation times obtained by dividing the maximum irradiation time of one shot, and for an irradiation unit area to which another group of the multiple groups is assigned, the process of assigning a subshot that includes a subshot other than the subshot pre-set for one of the same group, The process involves drawing a pattern on the sample by performing sub-shots assigned to each irradiation unit region irradiated by the multi-charged particle beam, with each shot using the multi-charged particle beam. Equipped with, For each group, sub-shots are assigned to other groups such that the total sub-irradiation time for each irradiation unit region of that group is calculated from the sum of the pre-set sub-irradiation times of the sub-shots assigned to one group and the sum of the sub-irradiation times of the sub-shots assigned to other groups. It is characterized by the following:

[0010] Furthermore, it is preferable that the sets consist of adjacent irradiation unit regions.

[0011] Furthermore, multiple irradiation unit areas are each subjected to multiple drawing using multiple shots. Preferably, the set consists of illumination unit regions whose positions overlap in each drawing process of the multiplex drawing.

[0012] Furthermore, it is preferable that the values ​​obtained based on irradiation time are values ​​calculated using a weighting system pre-set for each group.

[0013] A multi-charged particle beam lithography apparatus according to one aspect of the present invention is: A plurality of irradiation unit regions, which are unit regions irradiated by each beam of a multi-charged particle beam in which a drawing region of a sample is divided, and a plurality of sets each consisting of two or more irradiation unit regions are preset. For each irradiation unit region of the plurality of irradiation unit regions, one group out of a plurality of groups is assigned such that the groups are different between the irradiation unit regions in each set, and the plurality of irradiation unit regions irradiated in each shot of the multi-charged particle beam include groups of irradiation unit regions that are different. A group assignment processing unit for assignment; For an irradiation unit region to which one group of a plurality of groups is assigned among each irradiation unit region, out of a plurality of sub-shots of a plurality of sub-irradiation times obtained by dividing the maximum irradiation time for one shot, a sub-shot preset according to the irradiation time set for the irradiation unit region or a value obtained based on the irradiation time is assigned. For an irradiation unit region to which another group of the plurality of groups is assigned, a sub-shot including a sub-shot other than the sub-shot preset for one group of the same set is assigned. A sub-shot assignment processing unit for assignment; For each shot, a drawing mechanism that uses a multi-charged particle beam to perform a sub-shot assigned to each irradiation unit region irradiated with the multi-charged particle beam, thereby drawing a pattern on the sample; Comprising: The sub-shot assignment processing unit assigns sub-shots to other groups such that a value obtained from the sum of the sub-irradiation times of the sub-shots preset for one group and the sum of the sub-irradiation times of the sub-shots assigned to other groups for each set becomes the set irradiation time set for each irradiation unit region of the set. Characterized by the above.

Effect of the Invention

[0014] According to one aspect of the present invention, the current amount of the entire on-beam current that becomes on simultaneously can be reduced.

Brief Description of the Drawings

[0015] [Figure 1] It is a conceptual diagram showing the configuration of a drawing device in Embodiment 1. [Figure 2] It is a conceptual diagram showing the configuration of the shaping aperture array substrate in Embodiment 1. [Figure 3] It is a cross-sectional view showing the configuration of the blanking aperture array mechanism in Embodiment 1. [Figure 4] It is a conceptual diagram for explaining an example of the drawing operation in Embodiment 1. [Figure 5] It is a diagram showing an example of the irradiation region of the multi-beam and the drawing target pixel in Embodiment 1. [Figure 6] It is a diagram showing an example of the split shot of the multi-electron beam in Embodiment 1. [Figure 7] It is a conceptual diagram showing the internal configuration of the individual blanking control circuit and the common blanking control circuit in Embodiment 1. [Figure 8] It is a flowchart diagram showing an example of the main process steps of the drawing method in Embodiment 1. [Figure 9] It is a diagram showing an example of the assignment of groups to pixels in Embodiment 1. [Figure 10] It is a diagram showing an example of the combination of sub-shots for each partial combination irradiation time in Embodiment 1. [Figure 11] It is a diagram showing an example of the irradiation time of each group for each combination irradiation time in Embodiment 1. [Figure 12] It is a diagram for explaining an example of the multi-beam drawing operation in Embodiment 1. [Figure 13] It is a diagram showing an example of the positional relationship between the multi-electron beam and the pattern in Embodiment 1. [Figure 14] It is a diagram showing another example of the positional relationship between the multi-electron beam and the pattern in Embodiment 1. [Figure 15] It is a diagram showing an example of the stripe layer between the paths of the multiple drawing in Embodiment 2. [Figure 16] It is a diagram showing an example of the assignment of groups to pixels in Embodiment 2. [Figure 17]This figure shows another example of assigning groups to pixels in Embodiment 2. [Figure 18] This figure shows an example of a combination of sub-shots for each irradiation time set in Embodiment 3. [Figure 19] This figure shows an example of the irradiation time for each group for each set irradiation time in Embodiment 3. [Figure 20] This figure shows an example of assigning groups to pixels in Embodiment 4. [Figure 21] This figure shows an example of assigning groups to pixels in a modified example of Embodiment 4. [Modes for carrying out the invention]

[0016] In the following embodiments, a multi-electron beam using an electron beam will be described as an example of a multi-charged particle beam. However, the charged particle beam is not limited to an electron beam; it may also be a beam using charged particles such as an ion beam.

[0017] Embodiment 1. Figure 1 is a conceptual diagram showing the configuration of a lithography apparatus in Embodiment 1. In Figure 1, the lithography apparatus 100 includes a lithography mechanism 150 and a control system circuit 160. The lithography apparatus 100 is an example of a multi-charged particle beam lithography apparatus and an example of a multi-charged particle beam exposure apparatus. Furthermore, the lithography apparatus 100 is an example of a raster beam lithography apparatus. The lithography mechanism 150 includes an electron tube 102 (electron beam column) and a lithography chamber 103. Inside the electron tube 102 are an electron gun 201, an illumination lens 202, a shaping aperture array substrate 203, a blanking aperture array mechanism 204, a reduction lens 205, a single deflector 212, a limiting aperture substrate 206, an objective lens 207, a main deflector 208, and a sub-deflector 209.

[0018] An XY stage 105 is placed inside the drawing chamber 103. Samples 101, such as masks, which will be the substrates to be drawn on during drawing (exposure), are placed on the XY stage 105. Samples 101 include exposure masks used when manufacturing semiconductor devices, or semiconductor substrates (silicon wafers) on which semiconductor devices are manufactured. Samples 101 also include mask blanks with resist coated on them but with no drawings yet. A mirror 210 for measuring the position of the XY stage 105 is also placed on the XY stage 105.

[0019] The control system circuit 160 includes a control computer 110, memory 112, deflection control circuit 130, logic circuit 131, digital-to-analog converter (DAC) amplifier units 132 and 134, lens control circuit 136, stage control mechanism 138, stage position measuring instrument 139, and storage devices 140 and 142 such as magnetic disk drives. The control computer 110, memory 112, deflection control circuit 130, logic circuit 131, lens control circuit 136, stage control mechanism 138, stage position measuring instrument 139, and storage devices 140 and 142 are connected to each other via a bus (not shown). The deflection control circuit 130 is connected to DAC amplifier units 132 and 134, logic circuit 131, and blanking aperture array mechanism 204. The sub-deflector 209 is composed of four or more electrodes, and each electrode is controlled by the deflection control circuit 130 via the DAC amplifier 132. The main deflector 208 is composed of four or more electrodes, and each electrode is controlled by the deflection control circuit 130 via the DAC amplifier 134. The lens group, including the illumination lens 202, the reduction lens 205, and the objective lens 207, is controlled by the lens control circuit 136.

[0020] The position of the XY stage 105 is controlled by the drive of motors on each axis (not shown) controlled by the stage control mechanism 138. The stage position measuring instrument 139 measures the position of the XY stage 105 by receiving reflected light from the mirror 210 using the principle of laser interferometry.

[0021] The control computer 110 contains a rasterization processing unit 50, a dose calculation unit 52, an irradiation time calculation unit 54, a group assignment processing unit 56, a set irradiation time calculation unit 58, a sub-shot assignment processing unit 59, a data processing unit 70, a drawing control unit 72, and a transfer processing unit 74. Each of these "~ units" has a processing circuit. Such processing circuits include, for example, electrical circuits, computers, processors, circuit boards, quantum circuits, or semiconductor devices. Each of these "~ units" may use a common processing circuit (the same processing circuit) or different processing circuits (separate processing circuits). Information input to and output to the rasterization processing unit 50, dose calculation unit 52, irradiation time calculation unit 54, group assignment processing unit 56, set irradiation time calculation unit 58, sub-shot assignment processing unit 59, data processing unit 70, drawing control unit 72, and transfer processing unit 74, as well as information being calculated, are stored in the memory 112 each time.

[0022] The drawing operation of the drawing device 100 is controlled by the drawing control unit 72. Furthermore, the transfer process of the irradiation time data for each shot to the deflection control circuit 130 is controlled by the transfer processing unit 74.

[0023] Furthermore, drawing data (chip data) is input from outside the drawing device 100 and stored in the storage device 140. The chip data defines information about multiple graphic patterns that constitute the chip pattern. Specifically, for each graphic pattern, the coordinates of each vertex are defined in the order in which the graphic is formed. Alternatively, for example, for each graphic pattern, the graphic code, coordinates, and size are defined.

[0024] Here, Figure 1 shows the configuration necessary to explain Embodiment 1. The drawing device 100 may also have other configurations that are normally necessary.

[0025] Figure 2 is a conceptual diagram showing the configuration of a molded aperture array substrate in Embodiment 1. In Figure 2, the molded aperture array substrate 203 has p rows horizontally (x direction) × q rows vertically (y direction) (p,q≧2) holes (openings) 22 formed in a matrix at a predetermined arrangement pitch. In the example of Figure 2, for example, it shows a case where 512 × 512 rows of holes 22 are formed in the vertical and horizontal (x,y directions). The number of holes 22 is not limited to this. For example, 32 × 32 rows of holes 22 may be formed. Each hole 22 is formed as a rectangle of the same dimensions and shape. Alternatively, they may be circles of the same diameter. A portion of the electron beam 200 passes through each of these multiple holes 22, thereby forming a multi-electron beam 20. In other words, the molded aperture array substrate 203 forms and emits a multi-electron beam 20. The molded aperture array substrate 203 is an example of a source of emission of a multi-electron beam 20 or a multi-beam formation mechanism.

[0026] Figure 3 is a cross-sectional view showing the configuration of the blanking aperture array mechanism in Embodiment 1. As shown in Figure 3, the blanking aperture array mechanism 204 has a blanking aperture array substrate 31 made of a semiconductor substrate such as silicon placed on a support base 33. In the membrane region 330 in the center of the blanking aperture array substrate 31, through holes 25 (openings) for the passage of each beam of the multi-electron beam 20 are opened at positions corresponding to each hole 22 of the molded aperture array substrate 203 shown in Figure 2. Then, a set of control electrodes 24 and counter electrodes 26 (blankers: blanking deflectors) are placed at positions opposite each other across the corresponding through holes 25. In addition, a control circuit 41 (logic circuit) that applies a deflection voltage to the control electrode 24 for each through hole 25 is placed inside the blanking aperture array substrate 31 near each through hole 25. The counter electrodes 26 for each beam are connected to ground.

[0027] An amplifier (an example of a switching circuit), not shown in the diagram, is placed inside the control circuit 41. As an example of an amplifier, a CMOS (Complementary MOS) inverter circuit, which acts as a switching circuit, is placed inside. Either an L (low) potential (e.g., ground potential) that is lower than the threshold voltage, or an H (high) potential (e.g., 1.5V) that is higher than the threshold voltage, is applied as a control signal to the input (IN) of the CMOS inverter circuit. In Embodiment 1, when an L potential is applied to the input (IN) of the CMOS inverter circuit, the output (OUT) of the CMOS inverter circuit, which is the output of the control circuit 41, becomes a positive potential (Vdd). The electric field created by the potential difference with the ground potential of the counter electrode 26 deflects the corresponding beam, and the beam is controlled to turn OFF by being shielded by the limiting aperture substrate 206. On the other hand, when a high potential is applied to the input (IN) of the CMOS inverter circuit (active state), the output (OUT) of the CMOS inverter circuit and the control circuit 41 becomes ground potential, eliminating the potential difference with the ground potential of the counter electrode 26. As a result, the corresponding beam is not deflected, and the control is made so that the beam turns ON upon passing through the limiting aperture substrate 206. This deflection is used for blanking control.

[0028] Next, a specific example of the operation of the drawing mechanism 150 will be described. The electron beam 200 emitted from the electron gun 201 (emission source) illuminates the entire molded aperture array substrate 203 almost vertically by the illumination lens 202. Multiple rectangular holes 22 (openings) are formed in the molded aperture array substrate 203, and the electron beam 200 illuminates the area containing all of the multiple holes 22. Each portion of the electron beam 200 irradiated at the location of the multiple holes 22 passes through each of the multiple holes 22 in the molded aperture array substrate 203, thereby forming, for example, a rectangular multi-beam (multiple electron beams) 20. These multi-electron beams 20 pass through the corresponding blankers of the blanking aperture array mechanism 204. Each of these blankers individually blanks the passing beam so that the beam remains ON for a set drawing time (irradiation time).

[0029] The multi-electron beam 20, having passed through the blanking aperture array mechanism 204, is reduced by the reduction lens 205 and travels towards the central hole formed in the limiting aperture substrate 206. Here, the electron beam deflected by the blanker of the blanking aperture array mechanism 204 is positioned away from the central hole in the limiting aperture substrate 206 and is shielded by the limiting aperture substrate 206. On the other hand, the electron beam that was not deflected by the blanker of the blanking aperture array mechanism 204 passes through the central hole in the limiting aperture substrate 206, as shown in Figure 1. In this way, the limiting aperture substrate 206 shields each beam that has been deflected by the blanker of the blanking aperture array mechanism 204 to the beam-off state. Then, each beam of one shot is formed by the beams that have passed through the limiting aperture substrate 206 from the time the beam is turned ON until it is turned OFF. The multi-electron beam 20 that has passed through the limiting aperture substrate 206 is focused by the objective lens 207 to form a pattern image with a desired reduction ratio. The main deflector 208 and sub-deflector 209 then deflect the entire multi-electron beam 20 that has passed through the limiting aperture substrate 206 in the same direction, and each beam is directed to its respective irradiation position on the sample 101. Furthermore, for example, when the XY stage 105 is moving continuously, the main deflector 208 performs tracking control so that the irradiation position of the beam follows the movement of the XY stage 105. Ideally, the multi-electron beam 20 that is irradiated at one time will be arranged at a pitch obtained by multiplying the arrangement pitch of the multiple holes 22 in the molded aperture array substrate 203 by the desired reduction ratio described above.

[0030] Figure 4 is a conceptual diagram illustrating an example of the drawing operation in Embodiment 1. As shown in Figure 4, the drawing area 30 (thick line) of the sample 101 is virtually divided into multiple stripe-shaped areas 32 with a predetermined width in the y direction, for example. The example in Figure 4 shows a case where the drawing area 30 of the sample 101 is divided into multiple stripe areas 32 with a width size substantially the same as the size of the designed irradiation area 34 (drawing field) that can be irradiated with a single irradiation of the multi-electron beam 20 in the y direction. The size of the irradiation area 34 of the designed multi-electron beam 20 in the x direction can be defined by the number of beams in the x direction × the inter-beam pitch in the x direction. The size of the rectangular irradiation area 34 in the y direction can be defined by the number of beams in the y direction × the inter-beam pitch in the y direction.

[0031] First, the XY stage 105 is moved to adjust the position of the irradiation area 34 of the multi-electron beam 20 to the left edge of the first stripe area 32, or even further to the left, and the first stripe area 32 is drawn. When drawing the first stripe area 32, the drawing progresses relatively in the x direction by moving the XY stage 105, for example, in the -x direction. The XY stage 105 is moved continuously at a constant speed, for example. After the drawing of the first stripe area 32 is completed, the stage position is moved in the -y direction by the width of the stripe area 32.

[0032] Next, the irradiation area 34 of the multi-electron beam 20 is adjusted to be located at the left edge of the second stripe area 32, or even further to the left, and the drawing of the second stripe area 32 is performed by moving the XY stage 105, for example, in the -x direction, thereby relatively advancing the drawing in the x direction.

[0033] Furthermore, while the example in Figure 4 shows the case where each stripe region 32 is drawn in the same direction, this is not the only option. For example, for the stripe region 32 to be drawn after the stripe region 32 drawn in the x direction, the XY stage 105 can be moved, for example, in the x direction, so that the drawing is performed in the -x direction. By drawing while alternating directions in this way, the stage movement time can be shortened, and consequently, the drawing time can be shortened. In a single shot, the multi-beam formed by passing through each hole 22 of the molded aperture array substrate 203 forms up to the same number of shot patterns as each hole 22 at once.

[0034] Furthermore, while the example in Figure 4 shows the case where the stage is moved once for the drawing process of each stripe area, this is not the only option. It is also preferable to perform multiple drawing (multiple-path drawing) by moving the stage multiple times over the same position. In that case, for example, it is preferable to perform multiple drawing while shifting in the y direction by an amount equal to 1 / n of the width of the stripe area. Alternatively, it is also preferable to perform multiple drawing (in-path multiple drawing) in which the same position is drawn multiple times with different beams during a single stage movement.

[0035] Figure 5 shows an example of the irradiation area and drawing target pixels in Embodiment 1. In Figure 5, the stripe area 32 is divided into multiple mesh areas, for example, by the beam size of the multi-electron beam 20. Each of these mesh areas becomes a drawing target pixel 36. A pixel 36 is also called an irradiation unit area. The size of the drawing target pixel 36 is not limited to the beam size and may be composed of any size regardless of the beam size. For example, it may be composed of a size of 1 / n (where n is an integer of 1 or more) of the beam size. In the example in Figure 5, the drawing area of ​​the sample 101 is shown as being divided into multiple stripe areas 32 in the y direction, for example, with a width size that is substantially the same as the size of the irradiation area 34 (drawing field) that can be irradiated with one irradiation of the multi-electron beam 20. The size of the rectangular irradiation area 34 in the x direction can be defined by the number of beams in the x direction × the beam pitch in the x direction. The size of the rectangular irradiation area 34 in the y direction can be defined by the number of beams in the y direction × the beam pitch in the y direction. In the example in Figure 5, for example, a 512×512-row multibeam is shown as an 8×8-row multibeam. Within the irradiation area 34, multiple pixels 28 (beam drawing positions) that can be irradiated with a single shot of the multi-electron beam 20 are shown. The pitch between adjacent pixels 28 becomes the inter-beam pitch of the multibeam. A rectangular region enclosed by the size of the inter-beam pitch in the x,y directions constitutes one sub-irradiation area 29 (pitch cell region). In the example in Figure 5, each sub-irradiation area 29 is shown as being composed of, for example, 4×4 pixels.

[0036] Figure 6 shows an example of a split shot of a multi-electron beam in Embodiment 1. In Figure 6, the maximum irradiation time Ttr for one shot is divided into multiple sub-shots (split shots) with multiple sub-irradiation times. In other words, the maximum irradiation time Ttr for one shot of the multi-electron beam 20 is divided into n sub-shots (split shots) with different sub-irradiation times, for example, irradiating the same pixel 36. First, the gradation value Ntr is determined by dividing the maximum irradiation time Ttr by the quantization unit Δ (gradation value resolution). For example, if n=6, it is divided into 6 sub-shots. When defining the gradation value Ntr as a binary value with n digits, it is preferable to pre-set the quantization unit Δ so that the maximum irradiation time Ttr becomes gradation value Ntr=64. This results in a maximum irradiation time Ttr=64Δ. Then, as shown in Figure 6, the n sub-shots are divided into 2 digits k'=0 to 5. k’ It has one of the irradiation times of Δ. In other words, 32Δ(=2 5 Δ), 16Δ(=2 4 Δ), 8Δ(=2 3 Δ),4Δ(=2 2 Δ), 2Δ(=2 1 Δ), Δ(=2 0 Each sub-irradiation time is one of Δ. That is, one multi-beam shot is divided into a sub-shot with a sub-irradiation time tk' of 32Δ, a sub-shot with a sub-irradiation time tk' of 16Δ, a sub-shot with a sub-irradiation time tk' of 8Δ, a sub-shot with a sub-irradiation time tk' of 4Δ, a sub-shot with a sub-irradiation time tk' of 2Δ, and a sub-shot with a sub-irradiation time tk' of Δ. The n sub-shots that take place during one shot period are performed consecutively. The n sub-shots performed during one shot period are performed with the same beam for each of the 36 pixels.

[0037] In addition, the maximum irradiation time Ttr corresponds to the irradiation time for the pixel with the largest dose amount among all the pixels 36 within the drawing area 30 of the sample 101. In other words, it corresponds to the irradiation time when the dose amount becomes the largest and reaches its maximum. The drawing apparatus 100 determines a constant stage speed based on a shot cycle obtained by adding a setting time to such a maximum irradiation time Ttr.

[0038] Therefore, any irradiation time t (= NΔ) for irradiating each pixel 36 can be defined by a combination of at least one sub-shot selected from the sub-irradiation times of a set of sub-shot groups defined by 32Δ (= 2 5 Δ), 16Δ (= 2 4 Δ), 8Δ (= 2 3 Δ), 4Δ (= 2 2 Δ), 2Δ (= 2 1 Δ), and Δ (= 2 0 Δ), provided that the irradiation time is not zero.

[0039] FIG. 7 is a conceptual diagram showing the internal configurations of the individual blanking control circuit and the common blanking control circuit in the first embodiment. In FIG. 7, in each control circuit 41 for individual blanking control arranged in the blanking aperture array mechanism 204 within the drawing apparatus 100 main body, a shift register 40, a register 42, a register 44, and an amplifier 46 are arranged. The individual blanking control for each beam is controlled by, for example, a 1-bit control signal. That is, a 1-bit control signal is input to and output from the shift register 40, the register 42, the register 44, and the amplifier 46. Since the amount of information of the control signal is small, the installation area of the control circuit can be reduced. In other words, even when arranging a control circuit on the blanking aperture array mechanism 204 with a narrow installation space, more beams can be arranged with a smaller beam pitch. This can increase the current amount passing through the blanking plate, that is, improve the drawing throughput.

[0040] Furthermore, the logic circuit 131 for common blanking includes a register 50, a counter 52, and an amplifier 54. Unlike the amplifier 46, which provides independent control for each beam, this circuit only requires one circuit to provide ON / OFF control common to all beams. Therefore, even when a circuit for high-speed response is required, there are no issues with installation space or limitations on the current used by the circuit. Thus, this amplifier 54 operates at a significantly higher speed than the amplifier 46, which can be implemented on the blanking aperture array mechanism 204. This amplifier 54 is controlled, for example, by a 10-bit control signal. That is, for example, a 10-bit control signal is input and output to the register 50 and the counter 52.

[0041] In Embodiment 1, the blanking control of each beam is performed using both beam ON / OFF control by the individual blanking control circuits 41 described above, and beam ON / OFF control by the common blanking control logic circuit 131 that performs blanking control of the entire multi-beam system at once.

[0042] For example, the shift registers 40 in the control circuit 41 of the p x q beams in the same row are connected in series. Then, for example, the irradiation time data (ON / OFF control signals) for the corresponding subshot of the same row of beams in the p x q beams is transmitted in series, and for example, the irradiation time data for each beam is stored in the corresponding shift register 40 by p clock signals.

[0043] Then, upon receiving a read signal from the deflection control circuit 130, the individual register 42 reads and stores an ON / OFF signal according to the stored data (1 bit) for the k-th subshot. Additionally, the deflection control circuit 130 transmits the irradiation time data (10 bits) for the k-th subshot, and the register 50 for common blanking control stores the irradiation time data (10 bits) for the k-th subshot.

[0044] Next, the individual shot signal for the k-th sub-shot is output from the deflection control circuit 130 to the individual registers 44 for all beams. As a result, the individual registers 44 for each beam maintain the data stored in the individual registers 42 only for the duration that the individual shot signal is ON, and output a beam ON signal or beam OFF signal to the individual amplifiers 46 according to the maintained ON / OFF signal. Instead of the individual shot signal, a load signal to read and maintain and a reset signal to reset the stored information may be output to the individual registers 44. The individual amplifiers 46 apply a beam ON voltage or beam OFF voltage to the control electrodes 24 according to the input beam ON signal or beam OFF signal. Meanwhile, delayed from the individual shot signal, the common shot signal for the k-th sub-shot is output from the deflection control circuit 130 to the counter 52 for common blanking control. The counter 52 counts for the duration indicated by the ON / OFF control signal stored in the registers 50, and during that time outputs a beam ON signal to the common amplifier 54. The common amplifier 54 applies a beam ON voltage to the deflector 212 only for the duration that it receives the beam ON signal from the counter 52.

[0045] In the common blanking mechanism, for example, the ON / OFF switching of the individual blanking mechanism 47 is performed after the voltage stabilization time (settling time) S1 / S2 of the amplifier 46 has elapsed. After the individual amplifier is turned ON, the common amplifier 54 is turned ON after the settling time S1 of the individual amplifier 46 when switching from OFF to ON has elapsed. This eliminates beam irradiation with unstable voltage during the rise time of the individual amplifier 46. The common amplifier 54 is then turned OFF when the irradiation time of the target k sub-shot has elapsed. As a result, the actual beam is turned ON and irradiated onto the sample 101 when both the individual amplifier 46 and the common amplifier 54 are ON. Therefore, it is preferable that the ON time of the common amplifier 54 be controlled so that it matches the actual sub-irradiation time of the beam. On the other hand, if the common amplifier 54 is turned ON when the individual amplifier 46 is OFF, it is preferable to turn the common amplifier 54 ON after the individual amplifier 46 has turned OFF, and after the settling time S2 of the individual amplifier 46 when switching from ON to OFF has elapsed. This eliminates the need for beam irradiation with unstable voltages during the falling edge of the individual amplifier 46.

[0046] In recent electron beam lithography, there is a trend to reduce pixel size in order to improve the resolution of small patterns. As pixel size is reduced, pixels with a pattern area density (coverage) of 100% become dominant in the region where a graphic pattern is placed. In other words, the smaller the pixel is compared to the pattern size, the smaller the proportion of pixels that overlap the edge of the pattern relative to the total number of pixels included in the pattern region. Also, in regions where no graphic pattern is placed, the pattern area density (coverage) of pixels 36 becomes 0%. Therefore, adjacent pixels often end up with the same dose. Therefore, in Embodiment 1, pairs of pixels 36 are set in advance, and each pixel 36 is assigned one of several groups A and B such that each pixel 36 within a pair belongs to a different group, and the multiple pixels 28 irradiated by the multi-electron beam 20 for each shot include different groups. A detailed explanation follows below.

[0047] Figure 8 is a flowchart showing an example of the main steps of the drawing method in Embodiment 1. In Figure 8, the drawing method in Embodiment 1 involves a series of steps: a group assignment step (S100), a rasterization process (S102), a dose calculation step (S104), an irradiation time calculation step (S106), a set irradiation time calculation step (S108), a sub-shot assignment step (S120), a data processing step (S122), and a drawing step (S130).

[0048] In the group assignment process (S100), the group assignment processing unit 56 assigns one of the multiple groups to each of the multiple pixels 36 (irradiation unit areas), which are unit areas to which each beam of the multi-electron beam 20 is irradiated, and for each of the multiple pixels 36, which are pre-set sets of two or more pairs of pixels 36, one group is assigned to each of the multiple pixels 36 such that the pixels 36 in each pair belong to different groups, and the multiple pixels 36 irradiated in each shot of the multi-electron beam 20 belong to different groups. In other words, the group assignment processing unit 56 assigns one of the multiple groups to each of the multiple pixels 36 (irradiation unit areas), which are unit areas to which each beam of the multi-electron beam 20 is irradiated, and for each of the multiple pixels 36, which are pre-set sets of pairs of pixels 36, they belong to different groups, and the multiple pixels 36 irradiated in each shot of the multi-electron beam 20 belong to different groups.

[0049] Figure 9 shows an example of group assignment to pixels in Embodiment 1. In the example in Figure 9, first, each stripe region 32 of the sample 101 is divided into multiple rectangular regions 35 of the same size as the irradiation region 34 of the multi-electron beam 20. Also, the example in Figure 9 shows, for example, the case of a 2×2 multi-electron beam 20. It also shows the case where, for example, four pixels 36 are arranged between the beam pitches. In this case, the rectangular regions 35 of the same size as the irradiation region 34 will consist of, for example, 8×8 pixels. In the example shown in Figure 9, pairs are composed of adjacent pixels. Specifically, two pixels adjacent in the x-direction within the same sub-irradiation area 29 (beam pitch area) form one pair. For each pair, adjacent pixels 36 are assigned different groups from among multiple groups A and B. In this process, each group is assigned so that it alternates between the x and y directions.

[0050] Furthermore, each group is assigned such that the multiple pixels 28 irradiated by the multi-electron beam 20 in each shot include pixels from different groups. In the example in Figure 9, each group is assigned to a 2x2 multi-electron beam 20 such that adjacent beams in the x and y directions irradiate pixels 28 from different groups. It is preferable to assign pixels that are separated by one beam pitch in the x and y directions to different groups so that in every shot, half of the multi-beam exposes pixels from group A and the other half exposes pixels from group B, and the beams that expose groups A and B are uniformly distributed within the multi-beam array.

[0051] Note that pixels from the same group will be aligned at the boundary of the sub-illumination area 29, but this is acceptable because they belong to different groups.

[0052] As a rasterization process (S102), the rasterization processing unit 50 reads chip pattern data (drawing data) from the storage device 140 and performs rasterization. Specifically, for each pixel 36, it calculates the pattern density ρ(x) (pattern area density) of the graphic pattern placed within the pixel. For example, it is preferable to perform rasterization for each stripe region 32.

[0053] As a dose calculation step (S104), the dose calculation unit 52 calculates the dose amount to be incident on each pixel 36. Specifically, it operates as follows: The dose amount D can be calculated, for example, by multiplying a preset reference irradiation amount Dbase by the proximity effect correction irradiation amount Dp and the pattern area density ρ. The proximity effect correction irradiation amount Dp is given as a relative value normalized with the reference irradiation amount Dbase set to 1. Thus, it is preferable to determine the dose amount D in proportion to the area density of the pattern calculated for each pixel 36. For the proximity effect correction irradiation amount Dp, the drawing area (here, for example, the stripe area 32) is virtually divided into multiple proximity mesh areas (mesh areas for proximity effect correction calculation) in a mesh shape of a predetermined size. The size of the proximity mesh area is preferably set to about 1 / 10 of the area of ​​influence of the proximity effect, for example, about 1 μm. Then, the drawing data is read from the storage device 140, and for each proximity mesh area, the pattern density ρ' (pattern area density) of the pattern placed within that proximity mesh area is calculated.

[0054] Next, for each adjacent mesh region, a proximity effect correction dose Dp is calculated to correct for the proximity effect. Here, the size of the mesh region for calculating the proximity effect correction dose Dp does not need to be the same as the size of the mesh region for calculating the pattern area density ρ. Also, the correction model and calculation method for the proximity effect correction dose Dp can be the same as the method used in conventional single-beam lithography. A dose map is created in which dose amount data for every 36 pixels is defined.

[0055] When performing multiplex drawing, a dose map is created for each multiplex drawing process. In other words, a dose map is created for each stripe layer. The created dose maps are stored in the memory device 142.

[0056] As part of the irradiation time calculation process (S106), the irradiation time calculation unit 54 calculates the irradiation time t of the electron beam to inject the calculated dose amount D into each pixel 36. The irradiation time t can be calculated by dividing the dose amount D by the current density J. The irradiation time is calculated as an integer value that can be handled by the counter 54. For example, it is calculated as a 10-bit integer value. Hereinafter, it will be calculated as a 6-bit integer value. This creates an irradiation time map in which the irradiation time data for each pixel 36 is defined. The created irradiation time map is stored in the storage device 142.

[0057] As a group irradiation time calculation step (S108), the group irradiation time calculation unit 58 calculates the group irradiation time (nominal irradiation time of the group) for each group. Preferably, the average irradiation time (average value) of the irradiation times set for each pixel 36 in the group is used as the group irradiation time. Note that the group irradiation time obtained here is not limited to the average value, but may also be a center value, or other representative values ​​such as the minimum value or maximum value. In such cases, the group irradiation time calculation unit 58 calculates the average irradiation time of the irradiation times of the pixels in the group as the group irradiation time for each group. As described above, as the pixel size decreases, there are more pixels where the pattern area density is 100%. For example, when adjacent pixels in a graphic pattern form a group, the irradiation times of both pixels 36 are often the same. In that case, the average irradiation time, which is the group irradiation time, will also coincide with the irradiation time defined for each pixel 36. Also, for example, when adjacent pixels that straddle the edge of a graphic pattern form a group, the irradiation times of both pixels 36 will be different. In that case, the set illumination time, for example, the average illumination time, will not match the illumination time defined for each pixel 36. The illumination amount of pixels that straddle edges greatly affects the edge position of the pattern formed by drawing. Therefore, a threshold may be set for the difference in illumination amount (illumination time) of a set of pixels, and if the difference in illumination amount (illumination time) of a set of pixels is greater than the threshold, the set illumination time calculation step (S108) may be skipped, and the illumination time calculated in the illumination time calculation step (S106) may be used as is.

[0058] In the sub-shot assignment process (S120), the sub-shot assignment processing unit 59 assigns, for each pixel 36 to which one of the multiple groups is assigned, a sub-shot that is pre-set according to the irradiation time set for that pixel 36 or a value determined based on the irradiation time, from among multiple sub-irradiation times obtained by dividing the maximum irradiation time for one shot. For each pixel 36 to which another of the multiple groups is assigned, a sub-shot that includes a sub-shot other than the sub-shot pre-set for one of the same group. In other words, for each pixel 36 to which one of the multiple groups A and B is assigned (for example, group B), the sub-shot assignment processing unit 59 assigns at least one sub-shot (fixed bit sequence) that is pre-set according to the set irradiation time (an example of irradiation time or a value based on irradiation time) set for that pixel 36, from among multiple sub-shots of, for example, n=6. Then, the sub-shot assignment processing unit 59 assigns at least one sub-shot to each pixel 36 that has been assigned to another group (e.g., group A) of the same group (e.g., group B), including at least one sub-shot other than the pre-set sub-shot.

[0059] Figure 10 shows an example of a combination of subshots for each irradiation time set in Embodiment 1. Figure 11 shows an example of the irradiation time for each group for each set irradiation time in Embodiment 1. In Figure 10, the vertical axis shows the sub-shot time (sub-irradiation time of the sub-shot), and the horizontal axis shows the set irradiation time (grayscale value). In the example in Figure 11, the combinations of irradiation time for group A and irradiation time for group B are shown for the grayscale values ​​of each set irradiation time from k=0 to 63. Also, in the example in Figure 10, an example of the sub-shot combinations assigned to each group from k=25 to 50 within the k=0 to 63 grayscale levels is shown.

[0060] In Embodiment 1, for each group, sub-shots are assigned to other groups such that the value obtained from the sum of the sub-irradiation times of the pre-set sub-shots assigned to one group and the sum of the sub-irradiation times of the sub-shots assigned to other groups becomes the group irradiation time set for each pixel 36 of that group. In other words, in Embodiment 1, for each group, at least one sub-shot is assigned to another group (e.g., Group A) such that the average value of the sum of the sub-irradiation times of at least one pre-set sub-shot assigned to one group (e.g., Group B) and the sum of the sub-irradiation times of at least one sub-shot assigned to another group (e.g., Group A) becomes the group irradiation time set for each pixel 36 of that group.

[0061] In the example in Figure 10, for pairs of pixels with illumination times defined by grayscale values ​​k=25 to 31, a subshot of 32Δ is assigned to pixel 36 in group B as a pre-set subshot. Then, a combination of subshots is assigned to pixel 36 in group A, which includes at least one subshot other than the 32Δ subshot assigned to the pixel in group B.

[0062] For example, in a set irradiation time of k=25, a sub-shot of 32Δ is pre-set for group B, so as shown in Figure 11, group A is assigned at least one sub-shot totaling 18Δ, so that the average is 25Δ. In the example in Figure 10, a sub-shot of 16Δ and a sub-shot of 2Δ would be assigned.

[0063] For example, in a set irradiation time of k=26, a sub-shot of 32Δ is pre-set for group B, so as shown in Figure 11, group A is assigned at least one sub-shot totaling 20Δ, so that the average is 26Δ. In the example in Figure 10, a sub-shot of 16Δ and a sub-shot of 4Δ would be assigned.

[0064] For example, in a set irradiation time of k=27, a sub-shot of 32Δ is pre-set for group B, so as shown in Figure 11, group A is assigned at least one sub-shot totaling 22Δ, such that the average is 27Δ. In the example in Figure 10, a sub-shot of 16Δ, a sub-shot of 4Δ, and a sub-shot of 2Δ would be assigned.

[0065] For example, in a set irradiation time of k=28, a sub-shot of 32Δ is pre-set for group B, so as shown in Figure 11, group A is assigned at least one sub-shot totaling 24Δ, so that the average is 28Δ. In the example in Figure 10, a sub-shot of 16Δ and a sub-shot of 8Δ would be assigned.

[0066] For example, in a set irradiation time of k=29, a sub-shot of 32Δ is pre-set for group B, so as shown in Figure 11, group A is assigned at least one sub-shot totaling 26Δ, so that the average is 29Δ. In the example in Figure 10, a sub-shot of 16Δ, a sub-shot of 8Δ, and a sub-shot of 2Δ would be assigned.

[0067] For example, in a set irradiation time of k=30, a sub-shot of 32Δ is pre-set for group B, so as shown in Figure 11, group A is assigned at least one sub-shot totaling 28Δ, so that the average is 30Δ. In the example in Figure 10, a sub-shot of 16Δ, a sub-shot of 8Δ, and a sub-shot of 4Δ would be assigned.

[0068] For example, in a set irradiation time of k=31, a sub-shot of 32Δ is pre-set for group B, so as shown in Figure 11, group A is assigned at least one sub-shot totaling 30Δ, such that the average is 31Δ. In the example in Figure 10, a sub-shot of 16Δ, a sub-shot of 8Δ, a sub-shot of 4Δ, and a sub-shot of 2Δ would be assigned.

[0069] In the example in Figure 10, for the pixels in sets of illumination times defined by the grayscale values ​​k=32 to 47, the pixels 36 in group B are assigned the following pre-set subshots: a 16Δ subshot, an 8Δ subshot, a 4Δ subshot, a 2Δ subshot, and a 1Δ subshot. The pixels 36 in group A are then assigned a combination of subshots that includes at least one subshot other than the 16Δ subshot, 8Δ subshot, 4Δ subshot, 2Δ subshot, and 1Δ subshot assigned to the pixels in group B.

[0070] For example, in a set irradiation time of k=32, a sub-shot group totaling 31Δ is pre-set for group B, consisting of a 16Δ sub-shot, an 8Δ sub-shot, a 4Δ sub-shot, a 2Δ sub-shot, and a 1Δ sub-shot. As shown in Figure 11, group A is assigned at least one sub-shot totaling 33, such that the average is 32Δ. In the example in Figure 10, a 32Δ sub-shot and a 1Δ sub-shot would be assigned.

[0071] For example, in a set irradiation time of k=33, a sub-shot group totaling 31Δ is pre-set for group B, consisting of a 16Δ sub-shot, an 8Δ sub-shot, a 4Δ sub-shot, a 2Δ sub-shot, and a 1Δ sub-shot. As shown in Figure 11, group A is assigned at least one sub-shot totaling 35, such that the average is 33Δ. In the example in Figure 10, a 32Δ sub-shot, a 2Δ sub-shot, and a 1Δ sub-shot would be assigned.

[0072] For example, in a set irradiation time of k=34, a sub-shot group totaling 31Δ is pre-set for group B, consisting of a 16Δ sub-shot, an 8Δ sub-shot, a 4Δ sub-shot, a 2Δ sub-shot, and a 1Δ sub-shot. As shown in Figure 11, group A is assigned at least one sub-shot totaling 37, such that the average is 34Δ. In the example in Figure 10, a 32Δ sub-shot, a 4Δ sub-shot, and a 1Δ sub-shot would be assigned.

[0073] For example, in a set irradiation time of k=36, a sub-shot group totaling 31Δ is pre-set for group B, consisting of a 16Δ sub-shot, an 8Δ sub-shot, a 4Δ sub-shot, a 2Δ sub-shot, and a 1Δ sub-shot. As shown in Figure 11, group A is assigned at least one sub-shot totaling 41, such that the average is 36Δ. In the example in Figure 10, a 32Δ sub-shot, an 8Δ sub-shot, and a 1Δ sub-shot would be assigned.

[0074] For example, in a set irradiation time of k=37, a sub-shot group totaling 31Δ is pre-set for group B, consisting of a 16Δ sub-shot, an 8Δ sub-shot, a 4Δ sub-shot, a 2Δ sub-shot, and a 1Δ sub-shot. As shown in Figure 11, group A is assigned at least one sub-shot totaling 43, such that the average is 37Δ. In the example in Figure 10, a sub-shot of 32Δ, an 8Δ sub-shot, a 2Δ sub-shot, and a 1Δ sub-shot would be assigned.

[0075] For example, in a set irradiation time of k=38, a sub-shot group totaling 31Δ is pre-set for group B, consisting of a 16Δ sub-shot, an 8Δ sub-shot, a 4Δ sub-shot, a 2Δ sub-shot, and a 1Δ sub-shot. As shown in Figure 11, group A is assigned at least one sub-shot totaling 45, such that the average is 38Δ. In the example in Figure 10, a sub-shot of 32Δ, an 8Δ sub-shot, a 4Δ sub-shot, and a 1Δ sub-shot would be assigned.

[0076] For example, in a set irradiation time of k=40, a sub-shot group totaling 31Δ is pre-set for group B, consisting of a 16Δ sub-shot, an 8Δ sub-shot, a 4Δ sub-shot, a 2Δ sub-shot, and a 1Δ sub-shot. As shown in Figure 11, group A is assigned at least one sub-shot totaling 49, such that the average is 40Δ. In the example in Figure 10, a 32Δ sub-shot, a 16Δ sub-shot, and a 1Δ sub-shot would be assigned.

[0077] For example, in a set irradiation time of k=42, a sub-shot group totaling 31Δ is pre-set for group B, consisting of a 16Δ sub-shot, an 8Δ sub-shot, a 4Δ sub-shot, a 2Δ sub-shot, and a 1Δ sub-shot. As shown in Figure 11, group A is assigned at least one sub-shot totaling 53, such that the average is 42Δ. In the example in Figure 10, a sub-shot of 32Δ, a sub-shot of 16Δ, a sub-shot of 4Δ, and a sub-shot of 1Δ would be assigned.

[0078] For example, in a set irradiation time of k=45, a sub-shot group totaling 31Δ is pre-set for group B, consisting of a 16Δ sub-shot, an 8Δ sub-shot, a 4Δ sub-shot, a 2Δ sub-shot, and a 1Δ sub-shot. As shown in Figure 11, group A is assigned at least one sub-shot totaling 59, such that the average is 45Δ. In the example in Figure 10, the assigned sub-shots would be a 32Δ sub-shot, a 16Δ sub-shot, an 8Δ sub-shot, a 4Δ sub-shot, and a 1Δ sub-shot.

[0079] In the example in Figure 10, for pixels in sets of illumination times defined by the grayscale values ​​k=48 to 50, the pixels 36 in group B are assigned the following pre-set subshots: a 32Δ subshot, an 8Δ subshot, a 4Δ subshot, a 2Δ subshot, and a 1Δ subshot. The pixels 36 in group A are then assigned a combination of subshots that includes at least one subshot other than the 32Δ subshot, 8Δ subshot, 4Δ subshot, 2Δ subshot, and 1Δ subshot assigned to the pixels in group B.

[0080] For example, in a set irradiation time of k=48, a sub-shot group totaling 47Δ is pre-set for group B, consisting of a 32Δ sub-shot, an 8Δ sub-shot, a 4Δ sub-shot, a 2Δ sub-shot, and a 1Δ sub-shot. As shown in Figure 11, group A is assigned at least one sub-shot totaling 49, such that the average is 48Δ. In the example in Figure 10, a 32Δ sub-shot, a 16Δ sub-shot, and a 1Δ sub-shot would be assigned.

[0081] For example, in a set irradiation time of k=50, a sub-shot group totaling 47Δ is pre-set for group B, consisting of a sub-shot of 32Δ, a sub-shot of 8Δ, a sub-shot of 4Δ, a sub-shot of 2Δ, and a sub-shot of 1Δ. As shown in Figure 11, group A is assigned at least one sub-shot totaling 53, such that the average is 50Δ. In the example in Figure 10, the assigned sub-shots would be a sub-shot of 32Δ, a sub-shot of 16Δ, a sub-shot of 4Δ, and a sub-shot of 1Δ.

[0082] According to the example in Figure 11, when k=0, the irradiation time is zero. When k=1, a sub-shot with a 1Δ value is pre-set for group B. When k=2, a sub-shot with a 2Δ value is pre-set for group B. When k=3, a sub-shot with a 2Δ value and a sub-shot with a 1Δ value are pre-set for group B. When k=4, a sub-shot with a 4Δ value is pre-set for group B. When k=5, a sub-shot with a 4Δ value and a sub-shot with a 1Δ value are pre-set for group B. When k=6, a sub-shot with a 4Δ value and a sub-shot with a 2Δ value are pre-set for group B. When k=7, a sub-shot with a 4Δ value, a sub-shot with a 2Δ value, and a sub-shot with a 1Δ value are pre-set for group B.

[0083] For k=8 to 15, sub-shots with a Δ of 16 are pre-set for group B. For k=16 to 31, sub-shots with a Δ of 32 are pre-set for group B.

[0084] For k=32~47, sub-shots of 16Δ, 8Δ, 4Δ, 2Δ, and 1Δ are pre-set for group B.

[0085] For k=48~55, group B is pre-set with sub-shots of 32Δ, 8Δ, 4Δ, 2Δ, and 1Δ.

[0086] At k=56, sub-shots of 32Δ, 16Δ, and 8Δ are pre-set in group B. At k=57, sub-shots of 32Δ, 16Δ, 8Δ, and 1Δ are pre-set in group B. At k=58, sub-shots of 32Δ, 16Δ, 8Δ, and 2Δ are pre-set in group B. At k=59, sub-shots of 32Δ, 16Δ, 8Δ, 2Δ, and 1Δ are pre-set in group B. At k=60, sub-shots of 32Δ, 16Δ, 8Δ, and 4Δ are pre-set in group B. At k=61, sub-shots of 32Δ, 16Δ, 8Δ, 4Δ, and 1Δ are pre-set in group B. For k=62, subshots of 32Δ, 16Δ, 8Δ, 4Δ, and 2Δ are pre-set in group B. For k=63, subshots of 32Δ, 16Δ, 8Δ, 4Δ, 2Δ, and 1Δ are pre-set in group B.

[0087] The irradiation time data indicating the combination of subshots can be defined with 6 bits of data for n=6 split shots. For example, 100000 indicates a 32Δ (k'=5) subshot. For example, 010000 indicates a 16Δ (k'=4) subshot. For example, 001000 indicates an 8Δ (k'=3) subshot. For example, 000100 indicates a 4Δ (k'=2) subshot. For example, 000010 indicates a 2Δ (k'=1) subshot. For example, 000001 indicates a 2Δ (k'=0) subshot. Each bit value represents one subshot. For example, 111111 indicates a 32Δ subshot, a 16Δ subshot, an 8Δ subshot, a 4Δ subshot, a 2Δ subshot, and a 1Δ subshot. 000000 means the irradiation time is zero.

[0088] As described above, we will try to avoid using sub-shots with the same sub-irradiation time in both Group A and Group B. This will reduce the number of beams that are simultaneously ON during a single shot. Therefore, the average beam current during the shot cycle can be reduced.

[0089] As a data processing step (S122), the data processing unit 70 processes the irradiation time data, which represents the combination of sub-shots, so that it is sorted in shot order. The irradiation time data is then stored in the storage device 142.

[0090] Then, the transfer processing unit 74 transfers the irradiation time data to the deflection control circuit 130 in the order of the shots.

[0091] As a drawing process (S130), under the control of the drawing control unit 72, the drawing mechanism 150 draws a pattern on the sample 101 by performing sub-shots assigned to each pixel 36 irradiated by the multi-electron beam 20 for each shot. Sub-shots may be performed only when the corresponding irradiation time data turns on one or more beams, or when all beams are turned off. In the case of sub-shots where the irradiation time data turns off all beams, the individual amplifiers 46 remain OFF for all beams while the common amplifier 54 is turned ON.

[0092] Figure 12 is a diagram illustrating an example of multi-beam lithography operation in Embodiment 1. The example in Figure 12 shows the case where each sub-irradiation area 29 is lithographed with four different beams. Furthermore, the example in Figure 12 shows a lithography operation in which the XY stage 105 moves continuously at a speed of L, which is the distance of 8 beam pitches, while lithographing 1 / 4 (1 of the number of beams used for irradiation) of the area within each sub-irradiation area 29. In the lithography operation shown in the example in Figure 12, for example, while the XY stage 105 moves a distance L, which is the distance of 8 beam pitches, the sub-deflector 209 sequentially shifts the irradiation position (pixel 36) and lithographs (exposes) four different pixels within the same sub-irradiation area 29 by firing four shots of the multi-beam 20 in a shot cycle T. While these four pixels are being drawn (exposed), the entire multi-beam 20 is deflected collectively by the main deflector 208 to prevent the irradiation area 34 from shifting relative to the sample 101 due to the movement of the XY stage 105, thereby causing the irradiation area 34 to follow the movement of the XY stage 105. In other words, tracking control is performed. After one tracking cycle is completed, the tracking is reset and returned to the previous tracking start position. Since the drawing of the first pixel row from the right in each sub-irradiation area 29 has been completed, after the tracking reset, in the next tracking cycle, the sub-deflector 209 first deflects the beam to adjust (shift) its drawing position so that it can draw, for example, the second pixel row from the right in each sub-irradiation area 29 that has not yet been drawn. By repeating this operation while drawing the stripe area 32, the position of the irradiation area 34 of the multi-beam 20 moves sequentially as shown in the irradiation areas 34a, 34b, 34c, ... 34o in the lower part of Figure 4, and drawing is performed.

[0093] Figure 13 shows an example of the positional relationship between the multi-electron beam and the pattern in Embodiment 1. Figure 14 shows another example of the positional relationship between the multi-electron beam and the pattern in Embodiment 1. As the pixel size decreases, as shown in Figure 13, the entire multi-electron beam 20 often illuminates multiple pixels 36, the same number as the number of beams in the pattern. In this case, the pixels 36 illuminated by the entire multi-electron beam 20 consist of, for example, the same number of pixels in group A and the same number of pixels in group B, two of each. Therefore, the illumination times for each set of illuminated pixels 36 are often the same or close in value. Although the pixels inside the pattern have the same area ratio, for example, due to proximity effect correction, there may be a gentle gradient in the illumination amount for pixels inside the pattern. However, if the gradient in illumination amount is gentle, the illumination times for adjacent sets of illumination within the pattern will be the same or close in value. In particular, considering the rounding error of real numbers when representing the illumination amount with 10 bits, adjacent pixels inside the pattern often have virtually the same value. Therefore, the number of subshots that are simultaneously ON by the four beams divided into group A and group B can be reduced. Also, as shown in Figure 14, some pixels illuminated by, for example, two beams of the multi-electron beam 20 may be located inside the pattern, while the remaining pixels illuminated by, for example, two beams may be located at the pattern edge. In this case, two pixels located within the pattern are divided into groups A and B. The combined irradiation times of two pixels located within the pattern are often the same or close to the same value. Similarly, two pixels located at the edge of the pattern are divided into groups A and B. The combined irradiation times of two pixels located at the edge of the pattern are often the same or close to the same value. Therefore, the number of subshots that are simultaneously turned ON by the two beams, divided into group A and group B, irradiating the pixels within the pattern can be reduced. Similarly, the number of subshots that are simultaneously turned ON by the two beams, divided into group A and group B, irradiating the pixels at the edge of the pattern can be reduced. Therefore, in both the example in Figure 13 and the example in Figure 14, the number of subshots that are simultaneously turned ON during the shot period of the multi-electron beam 20 can be reduced. This allows for a reduction in the average beam current during the shot period. Generally, adjacent beams expose pixels with different coverage rates, and there may be many subshots that are simultaneously turned ON by adjacent beams. However, each beam in a multi-beam array exposes pixels that are mostly inside the pattern or in areas without a pattern, with few beams exposing pixels at the edges of the pattern. Therefore, if the average area density of the region exposed by the multi-beam array in one shot is relatively uniform, the method of this embodiment can reduce the number of subshots that are simultaneously turned ON.

[0094] Furthermore, although each pixel 36 will be illuminated with a beam of a different illumination time than originally intended, the dose amount is averaged across the pixels in the group due to the spatial averaging effect of blur (beam blur and resist blur) that is greater than the inter-pixel distance, thus reducing the difference in dose amount due to differences in illumination time for each pixel. As a result, positional shifts of the pattern can be avoided. In particular, the averaging effect can be further enhanced by alternating the groups in the x and y directions.

[0095] As described above, according to Embodiment 1, the number of ON beams during a single shot period can be reduced. Therefore, the average current amount of the total ON beam current that is turned on simultaneously can be reduced. As a result, the Coulomb effect can be reduced. Consequently, the beam resolution and / or the resolution of the drawing can be improved.

[0096] Embodiment 2. Embodiment 1 describes the case where adjacent pixels form a pair, but it is not limited to this. Embodiment 2 describes the case where multiple drawing processes form a pair. An example of the configuration of the drawing device in Embodiment 2 is the same as in Figure 1. Also, a flowchart showing an example of the main components of the drawing method in Embodiment 2 is the same as in Figure 8. The following content is the same as in Embodiment 1, except for points that are not specifically mentioned.

[0097] In Embodiment 2, each pixel 36 is subjected to multiple drawing using multiple shots. Furthermore, in Embodiment 2, the pairs consist of pixels whose positions overlap in each drawing process of the multiplexed drawing.

[0098] Figure 15 shows an example of a stripe layer between passes in multiplex drawing in Embodiment 2. The stripe region 32 of the first pass and the stripe region 32 of the second pass of multiplex drawing are set with a positional shift. For example, in the case of multiplicity N, the stripe layer is constructed with a shift in the y direction by 1 / N of the width of the stripe region. It may also be shifted in the x direction. Note that drawing the striped area 32 in a single stage movement is considered a single-pass drawing process. Drawing the same striped area repeatedly by moving between stages N times constitutes multiple drawing passes (N passes).

[0099] Note that while Figure 15 shows an example where the stripe region 32 is shifted by an amount greater than the pixel size, this is not the only case. It is also acceptable to shift the stripe region 32 by an amount less than the pixel size. Multiple stripe regions 32 may also be superimposed without shifting.

[0100] As a group assignment step (S100), the group assignment processing unit 56 assigns one of several groups to multiple pixels 36 such that the pixels 36 that are pre-set to form pairs for each of the multiple pixels 36, which are divided into stripe areas 32 (an example of a drawing area) for each pass of the multiple drawing, belong to different groups, and that the multiple pixels 36 irradiated in each shot of the multi-electron beam 20 include pixels 36 from different groups, and that the pixels that form pairs belong to stripes of different drawing passes.

[0101] Figure 16 shows an example of group assignment to pixels in Embodiment 2. Figure 17 shows another example of group assignment to pixels in Embodiment 2. In the examples in Figures 16 and 17, a pair consists of pixels 36 belonging to different stripes among the multiple stripes used for multi-pass drawing. For example, pixels that are in group A in the first drawing pass are assigned to group B in the second drawing pass. For example, pixels that are in group B in the first drawing pass are assigned to group A in the second drawing pass.

[0102] Furthermore, each group is assigned such that the multiple pixels 28 illuminated by the multi-electron beam 20 in each shot include pixels from different groups. The examples in Figures 16 and 17 show the case where, for a 2x2 multi-electron beam 20, each group is assigned such that adjacent beams in the x and y directions illuminate pixels 28 from different groups.

[0103] Note that the example in Figure 16 shows a case where each group is assigned so that the groups alternate in the x and y directions, similar to Figure 9. However, this is not the only case. As shown in Figure 17, for example, each group may be assigned to 29 sub-irradiation units so that the groups alternate in the x and y directions.

[0104] In Embodiment 2, since averaging is performed across multiple drawing passes, adjacent pixels do not need to belong to different groups. However, grouping pixels so that adjacent beams illuminate pixels 28 belonging to different groups is preferable because it results in a more uniform distribution of illumination for each multiple drawing pass and on-beams within the beam array for each shot.

[0105] The content of each subsequent step is the same as in Embodiment 1. If the pixel positions of Group A and Group B, which belong to different drawing stripes, are the same and overlap on the sample surface, the irradiation dose of the two pixels will be the same. If their positions are offset and overlap, the irradiation dose of the two pixels will often be different. In either case, each subsequent step can be carried out in the same manner as in Embodiment 1.

[0106] As described above, according to Embodiment 2, even when a set is formed between multiple drawing passes, the number of ON beams during a single shot period can be reduced, similar to Embodiment 1. Therefore, the average current amount of the total ON beam current that is turned on simultaneously can be reduced. As a result, the Coulomb effect can be reduced.

[0107] Embodiment 3. Embodiment 3 describes a configuration in which pre-set weights are applied between groups. An example of the configuration of the drawing device in Embodiment 3 is the same as in Figure 1. Also, a flowchart showing an example of the main components of the drawing method in Embodiment 3 is the same as in Figure 8. The following content is the same as in Embodiment 1 or Embodiment 2 unless otherwise specified.

[0108] The contents of each step from the group assignment step (S100) to the group irradiation time calculation step (S108) are the same as in Embodiment 1.

[0109] As a sub-shot assignment step (S120), the sub-shot assignment processing unit 59 assigns at least one pre-set sub-shot to each pixel 36 that is assigned to one of the multiple groups A and B (for example, group A), based on a value calculated using a pre-set weighting (for example, 120%) for one group (for example, group A) to the set irradiation time (irradiation time or a value based on the irradiation time) set for that pixel 36. Then, the sub-shot assignment processing unit 59 assigns at least one sub-shot to each pixel 36 that is assigned to another group of the multiple groups A and B (for example, group B), based on a value calculated using a pre-set weighting (for example, 80%) for the other group (for example, group B) to the set irradiation time (irradiation time or a value based on the irradiation time) set for that pixel 36. In other words, for a pixel 36 that is assigned to one group (for example, group A), the value obtained based on the irradiation time for which a sub-shot is assigned is the value calculated using a pre-set weighting for one group (for example, group A). Furthermore, for pixels 36 assigned to other groups (e.g., group B), the values ​​obtained based on the illumination time required for a sub-shot are values ​​calculated using the weightings pre-set for the other groups (e.g., group B).

[0110] Figure 18 shows an example of a combination of subshots for each irradiation time set in Embodiment 3. Figure 19 shows an example of the irradiation time for each group for each set of irradiation times in Embodiment 3. In Figure 18, the vertical axis shows the sub-shot time (sub-irradiation time of the sub-shot), and the horizontal axis shows the set irradiation time (grayscale value). In the example in Figure 17, the combinations of irradiation time for group A and irradiation time for group B are shown for the grayscale values ​​of each set irradiation time from k=0 to 63. In the example in Figure 18, an example of sub-shot combinations assigned to each group from k=26 to 52 within the k=0 to 63 grayscale levels is shown.

[0111] In Embodiment 3, similar to Embodiment 1, at least one sub-shot is assigned to each group such that the average of the sum of the sub-irradiation times of at least one sub-shot assigned to one group (e.g., Group A) and the sum of the sub-irradiation times of at least one sub-shot assigned to another group (e.g., Group B) becomes the set irradiation time for each pixel 36 in that group.

[0112] In the example in Figure 19, for example, when k=0, the irradiation time is zero. For example, when k=1, since it is difficult to apply the specified weighting, sub-shots with a Δ of 1 are set for both group A and group B. For example, when k=2, since it is difficult to apply the specified weighting, sub-shots with a Δ of 2 are set for both group A and group B. For example, when k=3, since it is difficult to apply the specified weighting, sub-shots with a Δ of 2 and sub-shots with a Δ of 1 are set for both group A and group B. For example, when k=4, since it is difficult to apply the specified weighting effect, sub-shots with a Δ of 4 are set for both group A and group B.

[0113] For example, when k=5, subshots with a 4Δ and subshots with a 2Δ are set in group A. Subshots with a 4Δ are set in group B. For example, when k=6, group A is set to have subshots with 4Δ, 2Δ, and 1Δ. Group B is set to have subshots with 4Δ and 1Δ. For example, when k=7, subshots with a Δ of 8 are set in group A. Subshots with 4Δ and 2Δ are set in group B.

[0114] For example, at k=27, subshots with a 32Δ are set in group A. Subshots with a 16Δ, a 4Δ, and a 2Δ are set in group B.

[0115] For example, at k=29, subshots with a 32Δ and 2Δ are set in group A. Subshots with a 16Δ and 8Δ are set in group B.

[0116] For example, at k=37, group A is set to have subshots with 32Δ, 8Δ, and 4Δ. Group B is set to have subshots with 16Δ, 8Δ, 4Δ, and 2Δ.

[0117] For example, when k=40, subshots with a 32Δ and subshots with a 16Δ are set in group A. Subshots with a 32Δ are set in group B.

[0118] The contents of each subsequent step are the same as in Embodiment 1.

[0119] As described above, according to Embodiment 3, even when differentiating irradiation times between groups by weighting, the number of ON beams during a single shot period can be reduced, similar to Embodiment 1 or Embodiment 2. Therefore, the average current amount of the total ON beam current that is turned on simultaneously can be reduced. As a result, the Coulomb effect can be reduced.

[0120] Embodiment 4. The embodiments described above explain the case where each pixel is divided into two groups, A and B, but the embodiments are not limited to this. Embodiment 4 describes a configuration in which each pixel is divided into three or more groups. An example of the configuration of the drawing device in Embodiment 4 is the same as in Figure 1. Also, a flowchart showing an example of the main components of the drawing method in Embodiment 4 is the same as in Figure 8. The following content is the same as in any of Embodiments 1 to 3, except for the points that are not specifically mentioned.

[0121] Figure 20 shows an example of group assignment to pixels in Embodiment 4. In the example shown in Figure 20, each pixel 36 is assigned to one of four groups A, B, C, and D. Groups A and B form pairs, and groups C and D form pairs. Within each sub-illumination area 29, adjacent 2x2 pixels 36 are assigned one from group A and one from group B, alternating between groups in the x and y directions. Similarly, adjacent 2x2 pixels 36 are assigned one from group C and one from group D, alternating between groups in the x and y directions.

[0122] Furthermore, each group is assigned such that the multiple pixels 28 irradiated by the multi-electron beam 20 in each shot include pixels from different groups. In this case, when irradiating pixels 36 of group A or B, each group is assigned such that, for the 2x2 multi-electron beam 20 in that shot, adjacent beams in the x and y directions irradiate pixels 28 of different groups A and B. When irradiating pixels 36 of group C or D, each group is assigned such that, for the 2x2 multi-electron beam 20 in that shot, adjacent beams in the x and y directions irradiate pixels 28 of different groups C and D.

[0123] The relationship between the combined irradiation time for groups A and B and the irradiation time for each individual group is determined by the table in Figure 11 or Figure 19. Similarly, the relationship between the combined irradiation time for groups C and D and the irradiation time for each individual group is determined by the table in Figure 11 or Figure 19. Therefore, the relationship shown in Figure 11 may be applied to the group A and B pair, and the weighted relationship in Figure 19 may be applied to the group C and D pair. Alternatively, the weighted relationship in Figure 19 may be applied to the group A and B pair, and the weighted relationship in Figure 19 may be applied to the group C and D pair. In this case, the weighting between groups A and B and the weighting between groups C and D may be changed. For example, the weighting between groups A and B may be set to 120%:80%, and the weighting between groups C and D may be set to 115%:85%.

[0124] The other details are the same as in any of Embodiments 1 to 3.

[0125] Figure 21 shows an example of group assignment to pixels in a modified version of Embodiment 4. In this modified version, as shown in Figure 21, the pixels to which groups C and D in Figure 20 are assigned are assigned to one group (blank in Figure 21). Thus, they are divided into three groups.

[0126] In this case, when illuminating pixels 36 of group A or B, each group is assigned to the 2x2 multi-electron beam 20 in that shot such that adjacent beams in the x and y directions illuminate pixels 28 of different groups A and B. When illuminating pixels 36 of the remaining group (blank area), each group is assigned to the 2x2 multi-electron beam 20 in that shot such that all pixels 36 of the remaining group (blank area) are illuminated.

[0127] Then, the relationship between the combined irradiation time for groups A and B and the irradiation time for each group is determined by applying the table in Figure 11 or Figure 19. For the remaining blank groups, the original irradiation times defined in the irradiation time map are applied. Therefore, for the blank groups, a combination of subshots that corresponds to the original irradiation time defined in the irradiation time map is assigned.

[0128] The other details are the same as in any of Embodiments 1 to 3.

[0129] As described above, even when dividing into three or more groups, the number of ON beams during a single shot period can be reduced. Therefore, the average current of the total ON beam currents that are turned on simultaneously can be reduced. As a result, the Coulomb effect can be reduced.

[0130] The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In the examples described above, only the case of correction for proximity effect was explained, but the invention is not limited to this.

[0131] Furthermore, while descriptions of the device configuration, control methods, and other parts not directly necessary for explaining the present invention have been omitted, it goes without saying that the necessary device configuration and control methods can be appropriately selected and used. For example, although the control unit configuration for controlling the drawing device 100 has been omitted, it goes without saying that the necessary control unit configuration can be appropriately selected and used.

[0132] Furthermore, all multi-charged particle beam lithography methods and apparatus that incorporate elements of the present invention and can be appropriately modified by those skilled in the art are included within the scope of the present invention. [Explanation of Symbols]

[0133] 10 beams 20 Multibeam 22 holes 23 electrodes 24 control electrodes 25 Passing hole 26 Counter electrode 29 Sub-irradiation area 30 drawing area 32 Stripe Area 34 Irradiation area 35 rectangular area 36 pixels 41 Control circuits 50 Rasterization Processing Unit 52 Dose calculation unit 54 Irradiation time calculation unit 56 Group Assignment Processing Unit 58 Set irradiation time calculation unit 59 Sub-shot allocation processing unit 70 Data Processing Department 72 Drawing Control Unit 74 Transfer Processing Unit 100 Drawing device 101 samples 102 Electronic Microscope Tube 103 Drawing room 105 XY Stages 110 Control Computer 112 memory 130 Deflection control circuit 131 Logic Circuits 132,134 DAC Amplifier Unit 136 Lens control circuit 138 Stage control mechanism 139 Stage position measuring instrument 140,142 Storage device 150 Drawing mechanism 160 Control System Circuits 200 electron beam 201 Electron Gun 202 Illumination Lens 203 Molded aperture array substrate 204 Blanking Aperture Array Mechanism 205 Reduction Lens 206 Limiting Aperture Substrate 207 Objective lens 208 Main deflector 209 Sub deflector 210 Mirror 330 Membrane area

Claims

1. The drawing area of ​​the sample is divided into multiple irradiation unit regions, each of which is irradiated by a multi-charged particle beam, and multiple sets consisting of two or more of the irradiation unit regions are predetermined, and for each irradiation unit region of the multiple irradiation unit regions, one group from the multiple groups is assigned such that the irradiation unit regions in each set are different from each other, and the multiple irradiation unit regions irradiated by each shot of the multi-charged particle beam are different from the irradiation unit regions of the group, and For each irradiation unit area, for the irradiation unit area to which one of the multiple groups is assigned, a subshot is assigned from among multiple sub-irradiation times obtained by dividing the maximum irradiation time for one shot, according to the irradiation time set for the irradiation unit area or a value obtained based on the irradiation time, and for the irradiation unit area to which another group of the multiple groups is assigned, a subshot including a subshot other than the pre-set subshot is assigned to the same group, The process involves drawing a pattern on the sample by performing sub-shots assigned to each irradiation unit region irradiated by the multi-charged particle beam for each shot, and Equipped with, For each of the aforementioned groups, sub-shots are assigned to the other groups such that the value obtained from the sum of the pre-set sub-irradiation times of the sub-shots assigned to one group and the sum of the sub-irradiation times of the sub-shots assigned to the other groups equals the set irradiation time set for each irradiation unit region of that group. A multi-charged particle beam lithography method characterized by the following:

2. The aforementioned set is composed of adjacent irradiation unit regions, The multi-charged particle beam lithography method according to claim 1, characterized in that it is as described above.

3. Each of the aforementioned multiple irradiation unit regions is subjected to multiple drawing using multiple shots. The aforementioned set is composed of irradiation unit regions whose positions overlap in each of the drawing processes of the multiplex drawing. The multi-charged particle beam lithography method according to claim 1, characterized in that it is as described above.

4. The value obtained based on the irradiation time is a value calculated using a weighting predetermined for each group. A multi-charged particle beam lithography method according to any one of features 1 to 3.

5. A group assignment processing unit assigns one group from among the plurality of groups to each irradiation unit region, where each beam of the multi-charged particle beam, which divides the drawing area of ​​the sample, is irradiated, and a plurality of sets consisting of two or more of the irradiation unit regions are predetermined, and for each irradiation unit region of the plurality of irradiation unit regions, the group is such that the irradiation unit regions in each set are different from the group and the plurality of irradiation unit regions irradiated in each shot of the multi-charged particle beam are different from the group of the irradiation unit region, A subshot assignment processing unit assigns, for each irradiation unit area to which one of the multiple groups is assigned, a subshot that is set in advance according to the irradiation time set for that irradiation unit area or a value determined based on the irradiation time, from among multiple subshots with multiple sub-irradiation times obtained by dividing the maximum irradiation time for one shot, and for the irradiation unit areas to which other groups of the multiple groups are assigned, a subshot that includes subshots other than the pre-set subshots to the same group, A drawing mechanism that draws a pattern on the sample by performing sub-shots assigned to each irradiation unit region irradiated by the multi-charged particle beam for each shot, Equipped with, The sub-shot assignment processing unit assigns sub-shots to the other groups such that the value obtained from the sum of the pre-set sub-irradiation times of the sub-shots assigned to one group and the sum of the sub-irradiation times of the sub-shots assigned to the other groups becomes the set irradiation time set for each irradiation unit region of the group. A multi-charged particle beam lithography apparatus characterized by the following features.

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