Method and program for lithography of multi-charged particle beams

Abstract

This invention provides a method for reducing the discrepancy between the designed pixel position and the actual beam position in multibeam lithography using a bitmap shift method. [Configuration] One aspect of the present invention is a multi-charged particle beam drawing method, characterized by comprising the steps of: creating bitmap data in which a value dependent on the dose amount of each pixel is defined for each of the multiple drawing regions, each of which is composed of multiple pixels consisting of regions divided into a mesh-like drawing area of ​​the sample; and performing tracking control to deflect the multi-charged particle beam so as to follow the movement of the stage on which the sample is placed, and then repeating a cycle of resetting the deflection amount, and during one tracking control, drawing pixels of the drawing region corresponding to the two or more bitmap data in multiple shots of the same beam of the multi-charged particle beam based on two or more bitmap data from the multiple bitmap data.

Description

Technical Field

[0001] The present invention relates to a multi-charged particle beam drawing method and program, and more particularly to a technique for correcting the positional deviation of a beam array during multiple drawing in a multi-beam drawing apparatus, for example.

Background Art

[0002] Lithography technology, which is responsible for the progress of semiconductor device miniaturization, is an extremely important process for generating patterns, being the only such process in the semiconductor manufacturing process. In recent years, with the increasing integration of LSIs, the circuit linewidth required for semiconductor devices has been continuously miniaturized year by year. Here, electron beam (electron beam) lithography technology inherently has excellent resolution, and lithography using an electron beam on a wafer or the like has been carried out.

[0003] For example, there is a drawing apparatus using a multi-beam. Compared with the case of drawing with a single electron beam, by using a multi-beam, a large number of beams can be irradiated at once, so the throughput can be significantly improved. In such a multi-beam type drawing apparatus, for example, an electron beam emitted from an electron gun is passed through a mask having a plurality of holes to form a multi-beam, and each beam is blanking-controlled, and each unshielded beam is reduced by an optical system and deflected by a deflector to be irradiated to a desired position on the sample.

[0004] Here, in multi-beam lithography, as a method for reducing gray scale error, a bitmap shift method has been studied (see, for example, Patent Document 1). In the bitmap shift method, the gray scale error is reduced by shifting pixels of a plurality of bitmaps and overlapping a part of them for drawing. However, there is a problem that a deviation occurs between the position of pixels in the design of a plurality of bitmaps and the actual beam position to be irradiated, and the desired effect of reducing the gray scale error cannot be obtained.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-030301 [Overview of the project] [Problems that the invention aims to solve]

[0006] One aspect of the present invention provides a method for reducing the discrepancy between the designed pixel position and the actual beam position in multibeam lithography using a bitmap shift method. [Means for solving the problem]

[0007] One embodiment of the present invention is a multi-charged particle beam lithography method, The process involves creating bitmap data in which each drawing area of ​​a sample is composed of multiple pixels consisting of regions divided into a mesh, and for each of the multiple drawing areas offset by less than or equal to the size of each pixel, a value is defined that depends on the dose amount of each pixel. After tracking control to deflect the multi-charged particle beam to follow the movement of the stage on which the sample is placed, the deflection amount is reset in a cycle that is repeated, and during one tracking control, based on two or more bitmap data from among multiple bitmap data, pixels in the drawing area corresponding to two or more bitmap data are drawn in multiple shots of the same multi-charged particle beam. It is characterized by having the following features.

[0008] Furthermore, in the drawing process, It is preferable that during a single tracking control, the same pixels in the drawing area corresponding to two or more bitmap data are drawn.

[0009] Alternatively, in the drawing process, It is preferable that during a single tracking control, different pixels in the drawing areas corresponding to two or more bitmap data are drawn.

[0010] Furthermore, in the drawing process, During the first tracking control, which is a single tracking control, two or more bitmap data, which are part of the bitmap data of multiple stripe regions, are drawn on the first beam of the multi-charged particle beam to represent two or more stripe regions. During a second tracking control, which is a single tracking control performed before or after the first tracking control, it is preferable to draw one or more pixels of a striped region with the first beam based on one or more bitmap data that are other parts of the bitmap data of multiple striped regions.

[0011] Furthermore, multiple drawing areas are divided in a direction linearly independent of the stage's movement direction, and each area has multiple stripe regions with an offset less than or equal to the size of the pixel region. The first tracking control and the second tracking control are preferably provided for each drawing of at least one of the multiple stripe regions.

[0012] A program according to one aspect of the present invention is: The process involves creating multiple bitmap data sets, each consisting of multiple pixels formed by dividing the sample's drawing area into a mesh-like region, and for each of the multiple drawing areas offset by less than or equal to the size of each pixel, a value is defined that depends on the dose amount of each pixel. The process of storing the created bitmap data in a memory device, The process involves reading the plurality of bitmap data from the storage device, performing tracking control to deflect the multi-charged particle beam to follow the movement of the stage on which the sample is placed, and then repeating a cycle of resetting the deflection amount, and during one tracking control, controlling the drawing mechanism to draw pixels in the drawing area corresponding to the two or more bitmap data based on two or more of the plurality of bitmap data in multiple shots of the same beam of the multi-charged particle beam, respectively. Have the computer execute it. [Effects of the Invention]

[0013] According to one aspect of the present invention, in multi-beam drawing using a bitmap shift method, it is possible to reduce the deviation between the designed pixel position and the actually irradiated beam position.

Brief Description of the Drawings

[0014] [Figure 1] It is a conceptual diagram showing the configuration of the drawing apparatus 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 flowchart showing an example of the main process steps of the drawing method in Embodiment 1. [Figure 6] It is a diagram showing an example of a plurality of bitmaps in Embodiment 1. [Figure 7] It is a diagram showing an example of the drawing sequence in Embodiment 1. [Figure 8] It is a diagram showing an example of a plurality of bitmaps in Modification 1 of Embodiment 1. [Figure 9] It is a diagram showing a part of an example of the drawing sequence in Modification 1 of Embodiment 1. [Figure 10] It is a diagram showing the remainder of an example of the drawing sequence in Modification 1 of Embodiment 1. [Figure 11] It is a diagram showing an example of a plurality of bitmaps in Modification 2 of Embodiment 1. [Figure 12] It is a diagram for explaining the drawing path in Modification 2 of Embodiment 1. [Figure 13] It is a diagram showing an example of the drawing sequence of the first pass in Modification 2 of Embodiment 1. [Figure 14] It is a diagram showing an example of the drawing sequence of the second pass in Modification 2 of Embodiment 1. [Figure 15] This figure shows a part of an example of a drawing sequence in modified example 3 of Embodiment 1. [Figure 16] This figure shows the remainder of an example of a drawing sequence in modified example 3 of Embodiment 1. [Figure 17] This figure shows another example of multiple bitmaps in Embodiment 1. [Figure 18] This figure shows an example of the relationship between dose amount and position when bitmap shifting is performed in Embodiment 1. [Figure 19] This figure shows an example of the relationship between edge displacement and position in Embodiment 1. [Modes for carrying out the invention]

[0015] In the following embodiments, an electron beam configuration will be described as an example of a 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.

[0016] 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. 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 source 201, an illumination lens 202, a shaping aperture array substrate 203, a blanking aperture array mechanism 204, a reduction lens 205, a limiting aperture substrate 206, an objective lens 207, a main deflector 208, and a sub-deflector 209.

[0017] 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.

[0018] The control system circuit 160 includes a control computer 110, memory 112, deflection control circuit 130, 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, 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 the DAC amplifier units 132 and 134 and the 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.

[0019] 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.

[0020] The control computer 110 contains a bitmap creation unit 50, a drawing 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 from the bitmap creation unit 50, the drawing data processing unit 70, the drawing control unit 72, and the transfer processing unit 74, as well as information being processed, are stored in the memory 112 each time.

[0021] 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.

[0022] 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, for example, the graphic code, coordinates, and size are defined.

[0023] Here, Figure 1 shows the configuration necessary to explain Embodiment 1. The drawing device 100 may also have other configurations that are normally necessary.

[0024] 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 holes (openings) 22 formed in a matrix with a predetermined arrangement pitch, arranged in p rows vertically (y direction) and q rows horizontally (x direction) (p,q≧2). In the example in Figure 2, for example, it shows a case where 512 × 512 rows of holes 22 are formed vertically and horizontally (x,y direction). 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 to form a multi-beam 20. In other words, the molded aperture array substrate 203 forms a multi-beam 20.

[0025] 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-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.

[0026] 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 applied to the control circuit 41 becomes a positive potential (Vdd), and the electric field caused by the potential difference with the ground potential of the counter electrode 26 deflects the corresponding beam, which is then shielded by the limiting aperture substrate 206 to turn the beam OFF. 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 becomes ground potential, and the potential difference with the ground potential of the counter electrode 26 disappears, so the corresponding beam is not deflected, and the control is made so that the beam turns ON when it passes through the limiting aperture substrate 206. Blanking control is performed by this deflection.

[0027] Next, a specific example of the operation of the drawing mechanism 150 will be described. The electron beam 200 emitted from the electron source 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-beams 20 pass through the corresponding blankers of the blanking aperture array mechanism 204. Each of these blankers individually blanks the beams passing through so that the beam remains ON for a set drawing time (irradiation time).

[0028] The multi-beam 20 that has passed through the blanking aperture array mechanism 204 is reduced by the reduction lens 205 and travels toward 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 moved 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 beam that has passed through the limiting aperture substrate 206 from the time the beam is turned ON until it is turned OFF. The multi-beams 20 that have passed through the limiting aperture substrate 206 are 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-beams 20 that have passed through the limiting aperture substrate 206 in the same direction, illuminating each beam at its respective irradiation position on the sample 101. Furthermore, for example, when the XY stage 105 is moving continuously, tracking control is performed by the main deflector 208 to deflect the beam so that the irradiation position of the beam follows the movement of the XY stage 105. Ideally, the multi-beams 20 irradiated at one time will be arranged at a pitch obtained by multiplying the array pitch of the multiple holes 22 in the molded aperture array substrate 203 by the desired reduction ratio described above.

[0029] 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 one multi-beam 20 irradiation in the y direction. The size of the irradiation area 34 of the designed multi-beam 20 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.

[0030] In addition, in the example shown in Figure 4, a stripe layer is set up that consists of multiple stripe regions 32 obtained by dividing the drawing region 30.

[0031] Next, an example of the drawing operation will be explained. First, the XY stage 105 is moved to adjust the position of the irradiation area 34 of the multi-beam 20 to the left edge of the first stripe area 32, or even further to the left. Then, 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 an amount equal to the width of the stripe area 32. This shifts the drawn stripe area 32 in the y direction by an amount equal to the width of the stripe area 32.

[0032] Next, the irradiation area 34 of the multi-beam 20 is adjusted to be located at the left edge of the second stripe area 32, or even further to the left. Then, by moving the XY stage 105, for example, in the -x direction, the drawing is advanced relatively in the x direction. This completes the drawing of the second stripe area 32. The drawing is then continued in the same manner for subsequent areas. In this way, the kth stripe area 32 is drawn during one movement of the XY stage 105 in the -x direction.

[0033] Furthermore, the drawing process progresses by repeating the tracking control described above and the tracking reset, which resets the amount of deflection after the beam has been deflected by the tracking control, thereby gradually moving the irradiation area 34 (34a~34o) as shown in the lower part of Figure 4. Each beam performs a predetermined number of shots on multiple pixels within a sub-irradiation area enclosed by the beam pitch size in the x and y directions on the surface of the sample 101. For example, let's assume that each sub-irradiation area enclosed by the beam pitch size of the multi-beam 20 irradiated on the sample 101 consists of 4 × 4 (=16) pixels. Then, for example, let's assume that 4 shots are performed during one tracking control, and during that time the XY stage 105 advances by 8 beam pitches. In this case, each sub-irradiation area enclosed by the beam pitch size will be drawn 4 pixels at a time during one tracking control. After a tracking reset, in the next tracking control, the same 4 pixels within the same sub-irradiation area will be drawn by another beam, for example, 8 spaces away in the x direction. Therefore, after 4 tracking controls, single drawing of all pixels in each sub-irradiation area is completed by 4 different beams. Therefore, the sample 101 is drawn once by the 32 (=4 × 8) beams arranged in the x-direction of each stage in the y-direction. If the multi-beam 20 consists of, for example, 64 beams in the x-direction, then multiple drawing with a multiplicity of 2 is possible according to the drawing method described above. The multiplicity can be further increased by arranging even more beams in the x-direction.

[0034] Alternatively, multiple drawing can be achieved by repeatedly drawing the same stripe area 32 by moving the XY stage 105 multiple times using the multi-beam required for single drawing.

[0035] In the comparative example of Embodiment 1, multiple bitmaps (e.g., two bitmaps) are created with a size smaller than the pixel size, for example, 1 / 2 pixel size, to shift (offset) the reference position of the stripe layer, and multiplex drawing is performed (bitmap shift method). In the bitmap shift method, gray errors that may occur in pixels are reduced by overlapping and drawing some of the pixels at the same relative position in multiple bitmaps (hereinafter referred to as "the same pixels"). In multiplex drawing, for example, the first drawing process should draw along the unshifted bitmap, and the second drawing should draw along the shifted bitmap, thereby reducing gray errors. However, there was a problem in that a discrepancy occurred between the design pixel positions of the multiple bitmaps and the actual beam irradiation position, preventing the desired gray error reduction effect from being obtained.

[0036] The causes of such problems include tracking deflection errors and / or distortion of the beam array shape of the multi-beam 20. In the main deflector 208 used for tracking control with a large amount of deflection, deflection errors are likely to occur if the deflection timing is different. Therefore, when the same pixel is drawn multiple times with tracking control at different timings, positional shifts are likely to occur. In addition, each beam experiences a shift in its irradiation position due to manufacturing errors and optical errors in the beam-forming holes 22. Therefore, distortion may occur in the beam array shape of the multi-beam 20. Therefore, when the same pixel is drawn multiple times with different beams, especially beams that are far apart, positional shifts are likely to occur.

[0037] Therefore, in Embodiment 1, multiplex drawing is performed for each pixel using the same beam and the same tracking control method with a bitmap shift method. This will be explained in detail below.

[0038] Figure 5 is a flowchart showing an example of the main steps of the drawing method in Embodiment 1. In Figure 5, the drawing method in Embodiment 1 performs a series of steps: a bitmap creation step (S102), a drawing sequence setting step (S104), and a drawing step (S106).

[0039] In the bitmap creation process (S102), first, the drawing data processing unit 70 calculates the irradiation amount D for each pixel 36. The irradiation amount D can be calculated, for example, by multiplying a pre-set reference irradiation amount Dbase by the proximity effect correction irradiation coefficient Dp and the pattern area density ρ. In this way, it is preferable to determine the irradiation amount D in proportion to the area density of the pattern calculated for each pixel 36. For the proximity effect correction irradiation coefficient 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) of a predetermined size. The size of the proximity mesh area is preferably set to about 1 / 10 of the area affected by the proximity effect, for example, about 1 μm. Then, the drawing data is read from the storage device 140, and the pattern area density ρ' of the pattern placed within each proximity mesh area is calculated.

[0040] Next, for each adjacent mesh region, a proximity effect correction irradiation coefficient Dp is calculated to correct for the proximity effect. Here, the size of the mesh region for which the proximity effect correction irradiation coefficient Dp is calculated does not need to be the same as the size of the mesh region for which the pattern area density ρ' is calculated. Furthermore, the correction model and calculation method for the proximity effect correction irradiation coefficient Dp can be the same as the method used in conventional single-beam lithography systems.

[0041] The drawing data processing unit 70 then calculates the irradiation time t of the electron beam to inject the calculated irradiation dose D into each pixel 36. The irradiation time t can be calculated by dividing the irradiation dose D by the current density J. This creates a dose map (actually an irradiation time map) for each pixel 36.

[0042] The bitmap creation unit 50 then creates bitmap data in which multiple pixels 36 are formed from areas where the stripe area 32 (an example of a drawing area) of the sample 101 is divided into a mesh-like structure, and for each of the multiple stripe areas 32 offset by a size less than or equal to the size of each pixel 36, a value dependent on the dose amount of each pixel is defined. In other words, the bitmap creation unit 50 creates multiple bitmap data (dose maps) in which multiple stripe areas 32 (an example of a drawing area) of the sample 101 are formed from a mesh-like structure, and for each of the multiple stripe areas 32 (an example of a drawing area) of the sample 101, which are offset from each other by a size less than or equal to the size of each pixel 36, a value dependent on the irradiation amount D (dose amount) is defined for each pixel that is an element of the bitmap (dose map) shown in each bitmap data, such as data indicating the irradiation time (irradiation time data).

[0043] Figure 6 shows an example of multiple bitmaps in Embodiment 1. In Embodiment 1, the multiple drawing areas are divided in a direction linearly independent of the movement direction of the XY stage 105 and have multiple stripe areas with an offset of less than or equal to the size of the pixel area. This will be explained in detail. In Figure 6, a first stripe layer and a second stripe layer are created for the drawing area 30, for example, by a size of less than or equal to the size of 36 pixels in the y direction. The first stripe layer is composed of multiple stripe areas 32-1 obtained by dividing the drawing area 30 with a predetermined width in the y direction. The second stripe layer is composed of multiple stripe areas 32-2 obtained by dividing the drawing area 30 with a predetermined width in the y direction. Therefore, the k-th stripe area 32-1 and the k-th stripe area 32-2 are shifted in position by a size of less than or equal to the size of 36 pixels in the y direction, for example. In the example in Figure 6, the stripe area 32-2 is set by shifting its position in the y direction by half the size of 36 pixels (shown as beam size Bs in the example in Figure 6; the same applies hereinafter) from the stripe area 32-1. Therefore, when stripe region 32-1 and stripe region 32-2 are superimposed, pixels at the same positions in the two stripe regions 32-1 and 32-2 partially overlap. In the example in Figure 6, half of the regions overlap in the y direction.

[0044] Since the number of multiplexed drawings changes depending on the number of bitmaps, the illumination amount D (illumination time) for each pixel 26 defined in each bitmap is defined as, for example, the obtained illumination amount D (illumination time) divided by the number of multiplexing attempts. For example, if you are originally using N-folded drawing and create n bitmaps per drawing process, the number of multiplexing attempts is Nn, so you define a value of 1 / (Nn) of the obtained illumination amount D (illumination time) for each pixel for the corresponding pixel in each bitmap.

[0045] As part of the drawing sequence setting process (S104), the drawing control unit 72 sets the drawing sequence.

[0046] Figure 7 shows an example of a drawing sequence in Embodiment 1. The example in Figure 7 shows the case where, for example, a 2x2 multi-beam 20 is used. The example in Figure 7 shows the case where a sub-irradiation area 29 enclosed by the beam pitch size on the surface of the sample 101 is composed of 2x2 pixels 36. Each stripe area 32-1, 32-2 can be divided into multiple rectangular areas 35 of the same size as the irradiation area 34. The same drawing process is repeated for each rectangular area 35. Since the rectangular areas 35 are the same size as the irradiation area 34, each rectangular area 35 contains 4x4 pixels 36. The example in Figure 7 shows the case where, for example, two shots of the multi-beam 20 are performed during one tracking control. Also, during one tracking control, the XY stage 105 moves, for example, by m beam pitch (for example, 1 beam pitch).

[0047] In the drawing sequence of Embodiment 1, the bitmaps are swapped for each shot during the same tracking control. In the example in Figure 7, bitmap A is used first, followed by bitmap B in each tracking control. The order of the bitmaps is not limited to this. In addition to the order A, B, A, B, ..., the order could also be, for example, A, B, B, A, A, B, .... It is sufficient that all the bitmaps are swapped during each tracking control.

[0048] Furthermore, within each sub-illumination area 29, a drawing sequence is set to draw each pixel in the order of, for example, bottom left, bottom right, top left, and top right. The order in which pixels are drawn is not limited to this. The order of the 2x2 pixels may be different. For example, it could be top left, top right, bottom left, and bottom right.

[0049] In the drawing process (S106), first, the drawing data processing unit 70 rearranges the irradiation time data in shot order according to the set drawing sequence. The irradiation time data is stored in the storage device 142. Then, the transfer processing unit 74 reads the irradiation time data from the storage device 142 in shot order and transfers it to the deflection control circuit 130.

[0050] Then, the drawing mechanism 150 performs tracking control to deflect the multi-beam 20 to follow the movement of the XY stage 105 on which the sample 101 is placed, and then repeats a cycle of resetting the deflection amount. During one tracking control, based on two or more bitmap data A and B from among the multiple bitmap data, the drawing mechanism 150 draws pixels 36 of stripe regions 32-1 and 32-2 corresponding to two or more bitmap data A and B, respectively, using multiple shots of the same beam of the multi-beam 20. In other words, based on the data of multiple bitmaps A and B, the drawing mechanism 150 performs tracking control to deflect the multi-beam 20 to follow the movement of the XY stage 105 on which the sample 101 is placed, and during the same tracking control, it draws pixels 36 of two or more stripe regions 32-1 and 32-2 indicated by the data of two or more bitmaps A and B from among the multiple bitmap data. In Embodiment 1, during the drawing process (S106), the same pixels 36 in stripe regions 32-1 and 32-2 corresponding to two or more bitmap data are drawn during a single tracking control. In other words, in Embodiment 1, the drawing mechanism 150 draws the same pixels 36 in the stripe regions indicated by multiple bitmaps using multiple shots of the same beam of the multi-beam 20 during each tracking control. For example, in the example in Figure 7, the drawing mechanism 150 draws the same pixels 36 in stripe regions 32-1 and 32-2 indicated by two bitmaps A and B using two shots of the same beam of the multi-beam 20 during each tracking control.

[0051] Specifically, it operates as follows: As shown in Figure 7, in the first tracking control, in shot 1, the beam is irradiated to the lower left pixel of each sub-irradiation area 29 using bitmap A, and in shot 2, the same pixel 36 is irradiated with the same beam as in shot 1 using bitmap B. The shot position of the multi-beam 20 for each shot during each tracking control is adjusted by beam deflection by the sub-deflector 209. Then, after these two shots, the tracking is reset.

[0052] Similarly, in the second tracking control, in shot 3, bitmap A is used to illuminate the lower right pixel of each sub-illumination area 29 with a beam, and in shot 4, bitmap B is used to illuminate the same pixel 36 with the same beam as in shot 3 (a different beam from shots 1 and 2). Then, after these two shots, the tracking is reset.

[0053] Similarly, in the third tracking control, in shot 5, bitmap A is used to illuminate the upper left pixel of each sub-illumination area 29 with a beam, and in shot 6, bitmap B is used to illuminate the same pixel 36 with the same beam as in shot 5 (a different beam from shots 1-4). Then, after these two shots, the tracking is reset.

[0054] Similarly, in the fourth tracking control, in shot 7, bitmap A is used to illuminate the upper right pixel of each sub-illumination area 29 with a beam, and in shot 8, bitmap B is used to illuminate the same pixel 36 with the same beam as in shot 7 (a different beam from shots 1-6). Then, after these two shots, the tracking is reset.

[0055] With the above steps, the drawing of all pixels 36 within the rectangular region 35 is completed. By continuing the drawing process in the same manner, the entirety of the stripe regions 32-1 and 32-2 can be drawn. By drawing similarly for each stripe region, the drawing of the entire drawing region 30 of sample 101 is completed.

[0056] In Embodiment 1, since the same pixels 36 of each bitmap are drawn with the same beam during the same tracking control, the effects of tracking deflection errors and beam array distortion can be eliminated or reduced. Therefore, grayscale errors can be reduced.

[0057] Next, a modified example of Embodiment 1 will be described. In the bitmap creation process (S102) of the modified example 1, the bitmap creation unit 50 creates two bitmap (dose map) data, A and B, for multiple stripe regions 32 of the sample 101, which are offset from each other by half the size of the pixels 36, and each bitmap data defines a value that depends on the irradiation amount D (dose amount) for each pixel 36.

[0058] Figure 8 shows an example of multiple bitmaps in Modification 1 of Embodiment 1. In Figure 8, a first stripe layer and a second stripe layer are created for the drawing area 30, for example, by shifting their position in the y-direction by a size of 36 pixels or less. The example in Figure 8 shows the case where the rectangular area 36 is composed of 6 × 6 (=36) pixels. In the example in Figure 8, stripe area 32-2 is set by shifting its position in the y-direction by half the size Bs of the pixels 36 from stripe area 32-1. In the example in Figure 8, 1 / 2 of the area overlaps in the y-direction. Other points are the same as in Figure 6.

[0059] As part of the drawing sequence setting step (S104) in the modified example 1, the drawing control unit 72 sets the drawing sequence.

[0060] Figure 9 shows a part of an example of the drawing sequence in Modification 1 of Embodiment 1. Figure 10 shows the remainder of an example of a drawing sequence in Modification 1 of Embodiment 1. The examples in Figures 9 and 10 show, for example, the case where a 2×2 multi-beam 20 is used. The examples in Figures 9 and 10 show the case where a sub-irradiation area 29 enclosed by the beam pitch size on the surface of sample 101 is composed of 3×3 pixels 36. Each stripe area 32-1, 32-2 can be divided into multiple rectangular areas 35 of the same size as the irradiation area 34. Therefore, each rectangular area 35 contains 6×6 pixels 36. The examples in Figures 9 and 10 show the case where, for example, three shots of the multi-beam 20 are performed during one tracking control. Also, during one tracking control, the XY stage 105 moves, for example, by 1 beam pitch.

[0061] In the drawing sequence of Embodiment 1, the bitmaps are swapped for each shot during the same tracking control. In the example in Figure 9, during the first tracking control, bitmap A is used first, then bitmap B, and finally bitmap A is used. During the second tracking control, bitmap B is used first, then bitmap A, and finally bitmap B is used. This process is repeated thereafter. The order of the bitmaps is not limited to this. In addition to the order A, B, A, B, A, B, ..., the order may also be, for example, A, B, B, A, A, B, ...

[0062] Furthermore, within each sub-illumination area 29, bitmap A is set to draw each pixel in the following order: 1st column from the left and 1st row from the bottom, 2nd column from the left and 1st row from the bottom, 2nd column from the left and 2nd row from the bottom, 1st column from the left and 2nd row from the bottom, 1st column from the left and 3rd row from the bottom, 3rd column from the left and 1st row from the bottom, 3rd column from the left and 3rd row from the bottom, 3rd column from the left and 2nd row from the bottom, and 2nd column from the left and 3rd row from the bottom. Bitmap B sets a drawing sequence in which each pixel is drawn in the following order: second column from the left and second row from the bottom, first column from the left and first row from the bottom, second column from the left and first row from the bottom, second column from the left and third row from the bottom, first column from the left and second row from the bottom, first column from the left and third row from the bottom, third column from the left and first row from the bottom, third column from the left and third row from the bottom, and third column from the left and second row from the bottom. However, the order in which the pixels are drawn is not limited to this. In each bitmap, the order of the 3x3 pixels may be different.

[0063] In the drawing process (S106) of the modified example 1, first, the drawing data processing unit 70 rearranges the irradiation time data in shot order according to the set drawing sequence. The irradiation time data is stored in the storage device 142. Then, the transfer processing unit 74 reads the irradiation time data from the storage device 142 in shot order and transfers it to the deflection control circuit 130.

[0064] In the modified example 1 of Embodiment 1, during the drawing process, different pixels 36 in stripe regions 32-1 and 32-2 corresponding to two or more bitmap data are drawn during a single tracking control. In other words, during each tracking control, the drawing mechanism 150 draws different pixels 36 in the stripe regions (relative positions within them) indicated by multiple bitmaps using multiple shots of the same beam of the multi-beam 20. For example, in the examples of Figures 9 and 10, the drawing mechanism 150 draws different pixels 36 in stripe regions 32-1 and 32-2 indicated by two bitmaps A and B using three shots of the same beam of the multi-beam 20 during each tracking control.

[0065] Specifically, it operates as follows: As shown in Figure 9, in the first tracking control, in Shot 1, bitmap A is used to draw the pixels in the first column from the left and the first row from the bottom of each sub-irradiation area 29; in Shot 2, using the same beam as in Shot 1, bitmap B is used to draw the pixels in the second column from the left and the second row from the bottom of each sub-irradiation area 29; and in Shot 3, using the same beam as in Shots 1 and 2, bitmap A is used to draw the beam to the pixels in the second column from the left and the first row from the bottom of each sub-irradiation area 29. The shot position of the multi-beam 20 for each shot during tracking control is adjusted by beam deflection by the sub-deflector 209. Then, after these three shots, the tracking is reset.

[0066] Similarly, in the second tracking control, in shot 4, the first column from the left and the first row from the bottom of each sub-irradiation area 29 is drawn using bitmap B with the beam from shot 3 and an adjacent beam; in shot 5, the second column from the left and the second row from the bottom of pixels 36 are drawn using bitmap A with the same beam as shot 4; and in shot 6, the second column from the left and the first row from the bottom of pixels 36 are drawn using bitmap B with the same beam as shots 4 and 5. After these three shots, the tracking is reset.

[0067] Similarly, in the third tracking control, in shot 7, the first column from the left and the second row from the bottom of each sub-irradiation area 29 are drawn using bitmap A with the beam of shot 6 and an adjacent beam; in shot 8, the second column from the left and the third row from the bottom of pixels 36 are drawn using bitmap B with the same beam as shot 7; and in shot 9, the first column from the left and the third row from the bottom of pixels 36 are drawn using bitmap A with the same beam as shots 6 and 7. After these three shots, the tracking is reset.

[0068] Similarly, in the fourth tracking control, in shot 10, the first column from the left and the second row from the bottom of each sub-irradiation area 29 are drawn using bitmap B with the beam of shot 9 and an adjacent beam; in shot 11, the third column from the left and the first row from the bottom of pixels 36 are drawn using bitmap A with the same beam as shot 10; and in shot 12, the first column from the left and the third row from the bottom of pixels 36 are drawn using bitmap B with the same beam as shots 10 and 11. After these three shots, the tracking is reset.

[0069] Similarly, in the fifth tracking control, in shot 13, the third column from the left and the third row from the bottom of each sub-irradiation area 29 are drawn using bitmap A with the beam of shot 12 and an adjacent beam; in shot 14, the third column from the left and the first row from the bottom of pixel 36 are drawn using bitmap B with the same beam as shot 13; and in shot 14, the third column from the left and the second row from the bottom of pixel 36 are drawn using bitmap A with the same beam as shots 13 and 14. After these three shots, the tracking is reset.

[0070] Similarly, in the sixth tracking control, in shot 16, the third column from the left and the third row from the bottom of each sub-irradiation area 29 are drawn using bitmap B with the beam of shot 12 and an adjacent beam; in shot 17, the second column from the left and the third row from the bottom of pixels 36 are drawn using bitmap A with the same beam as shot 16; and in shot 17, the third column from the left and the second row from the bottom of pixels 36 are drawn using bitmap A with the same beam as shots 16 and 17. After these three shots, the tracking is reset.

[0071] With the above steps, the drawing of all pixels 36 within the rectangular region 35 is completed. By continuing the drawing process in the same manner, the entirety of the stripe regions 32-1 and 32-2 can be drawn. By drawing similarly for each stripe region, the drawing of the entire drawing region 30 of sample 101 is completed.

[0072] In Modification 1 of Embodiment 1, the same pixels 36 of each bitmap are drawn with adjacent beams during adjacent tracking control, thereby reducing the effects of tracking deflection error and beam array distortion. Therefore, grayscale errors can be reduced.

[0073] Next, a modified example 2 of Embodiment 1 will be described. In the bitmap creation process (S102) of the modified example 2, the bitmap creation unit 50 creates four bitmaps (dosemaps) A, B, C, and D for multiple stripe regions 32 of the sample 101, each shifted in position by 1 / 4 the size of the pixels 36, with each stripe region 32 having a value that depends on the irradiation amount D (dose amount) for each pixel 36.

[0074] Figure 11 shows an example of multiple bitmaps in a modified example 2 of Embodiment 1. In Figure 11, a first stripe layer is created relative to the drawing area 30, a second stripe layer is shifted in the y-direction by, for example, 1 / 4 the size of the pixels 36, a third stripe layer is further shifted in the y-direction by, for example, 1 / 4 the size of the pixels 36, and a fourth stripe layer is further shifted in the y-direction by, for example, 1 / 4 the size of the pixels 36. The example in Figure 11 shows the case where the rectangular area 35 consists of 4 × 4 (=16) pixels. In the example in Figure 11, stripe area 32-2 is set by shifting the position in the y-direction from stripe area 32-1 by 1 / 4 the size Bs of the pixels 36. Similarly, stripe area 32-3 is set by shifting the position in the y-direction from stripe area 32-1 by 2 / 4 the size Bs of the pixels 36. Similarly, stripe region 32-4 is set by shifting its position in the y-direction by 3 / 4 of the size Bs of pixel 36 from stripe region 32-1. In the example in Figure 11, 1 / 4 of the area in the y-direction overlaps for all bitmaps. The rest is the same as in Figure 6.

[0075] As part of the drawing sequence setting step (S104) in the modified example 2, the drawing control unit 72 sets the drawing sequence.

[0076] Figure 12 is a diagram illustrating the drawing path in a modified example 2 of Embodiment 1. In the example in Figure 12, the kth stripe region 32-1 of bitmap A and the kth stripe region 32-3 of bitmap C are drawn during one run of the XY stage 105 in the -x direction (path 1). Then, the XY stage 105 is moved back to the starting position for drawing the kth stripe region, and the kth stripe region 32-2 of bitmap B and the kth stripe region 32-4 of bitmap D are drawn during one run of the XY stage 105 in the -x direction (path 2).

[0077] Alternatively, the four bitmaps can be divided into pairs and assigned to one of the two stripe paths.

[0078] Note that while Figure 12 illustrates the case where bitmaps A and C are divided into two sets, and bitmaps B and D, this is not the only example. For example, it could also be divided into two sets, A and B, and bitmaps C and D. Or, for example, it could be divided into two sets, A and D, and bitmaps B and C.

[0079] Figure 13 shows an example of the first pass drawing sequence in a modified example 2 of Embodiment 1. Figure 14 shows an example of the second pass drawing sequence in a modified example 2 of Embodiment 1. The examples in Figures 13 and 14 show, for example, the use of a 2x2 multi-beam 20. The examples in Figures 13 and 14 show a sub-irradiation area 29 enclosed by the beam pitch size on the surface of the sample 101, which is composed of 2x2 pixels 36. Each stripe area 32-1, 32-2, 32-3, 32-4 is divided into multiple rectangular areas 35 of the same size as the irradiation area 34. Thus, each rectangular area 35 contains 4x4 pixels 36. The examples in Figures 13 and 14 show a case where the multi-beam 20 is used for, for example, two shots during one tracking control. Also, during one tracking control, the XY stage 105 moves by m beam pitch (e.g., 1 beam pitch).

[0080] In the drawing sequence of the modified example 2 of Embodiment 1, the bitmaps are swapped for each shot during the same tracking control. In the example in Figure 13, in the first tracking control, bitmap A is used first, then bitmap C is used. In the second tracking control, bitmap A is used first, then bitmap C is used. This is repeated thereafter. The order of the bitmaps is not limited to this. In addition to the order A, C, A, C, ..., the order may also be, for example, A, C, C, A, A, C, .... It is sufficient that, for example, bitmaps A and C are swapped during each tracking control.

[0081] Similarly, in the example in Figure 14, in the first tracking control, bitmap B is used first, followed by bitmap D. In the second tracking control, bitmap B is used first, followed by bitmap D. This process is repeated thereafter. The order of the bitmaps is not limited to this. In addition to the order A, C, A, C, ..., an order such as B, D, D, B, B, D, ... is also acceptable. It is sufficient if, for example, bitmaps B and D are swapped during each tracking control.

[0082] Furthermore, within each sub-illumination area 29, a drawing sequence is set to draw each pixel in the order of, for example, bottom left, bottom right, top left, and top right. The order in which pixels are drawn is not limited to this. The order of the 2x2 pixels may be different. For example, it could be top left, top right, bottom left, and bottom right.

[0083] In the drawing process (S106) of the modified example 2, first, the drawing data processing unit 70 swaps the irradiation time data in shot order for each pass, according to the set drawing sequence. The irradiation time data is stored in the storage device 142. Then, the transfer processing unit 74 transfers the irradiation time data from the storage device 142 to the deflection control circuit 130 in shot order.

[0084] Then, based on the data of multiple bitmaps A, B, C, and D, the drawing mechanism 150 draws pixels 36 of two or more stripe regions 32-1, 32-3 (32-2, 32-4) indicated by the data of two or more bitmaps A, C (B, D) during one of the multiple tracking controls which deflects the multibeam 20 to follow the movement of the XY stage 105 on which the sample 101 is placed, using multiple shots of the same beam of the multibeam 20.

[0085] In other words, in the modified example 2 of Embodiment 1, during the drawing process, during a first tracking control, which is one tracking control, two or more pixels of stripe regions are drawn with the first beam of the multibeam 20 based on two or more bitmap data, which are part of the bitmap data of multiple stripe regions. Then, during a second tracking control, which is one tracking control performed before or after the first tracking control, one or more pixels of stripe regions are drawn with the first beam based on one or more bitmap data, which are other part of the bitmap data of multiple stripe regions. Furthermore, the first tracking control and the second tracking control are provided for each drawing of at least one of the multiple stripe regions.

[0086] To put it another way, in the modified example 2 of Embodiment 1, the drawing mechanism 150 draws pixels 36 of two or more stripe regions 32-1, 32-3 represented by the data of two or more bitmaps A, B, C, and D, among the data of multiple bitmaps A, B, C, and D, using multiple shots of the same beam of the multi-beam 20 during each tracking control, and performs drawing processing on the entirety of these two or more stripe regions 32-1, 32-3. Furthermore, during each tracking control, the drawing mechanism 150 draws pixels 36 of one or more stripe regions 32-2, 32-4 represented by the data of one or more other bitmaps B, D among the data of multiple bitmaps A, B, C, D, using one or more shots of the same beam of the multi-beam 20, and performs drawing processing on the entire one or more other stripe regions 32-2, 32-4. Furthermore, the drawing process for the entirety of two or more of these striped areas 32-1, 32-3 and the drawing process for the entirety of one or more of the other striped areas 32-2, 32-4 are performed after one of them has been completed.

[0087] Furthermore, in the modified example 2 of Embodiment 1, the drawing mechanism 150 draws the same pixels 36 in stripe regions 32-1, 32-3 (32-2, 32-4) indicated by multiple bitmaps using multiple shots of the same beam of the multi-beam 20 during each tracking control, for each pass. In the example in Figure 13, the drawing mechanism 150 draws the same pixels 36 in stripe regions 32-1, 32-3 indicated by two bitmaps A, C using two shots of the same beam of the multi-beam 20 during each tracking control in the first pass. In the example in Figure 14, the drawing mechanism 150 draws the same pixels 36 in stripe regions 32-2, 32-4 indicated by two bitmaps B, D using two shots of the same beam of the multi-beam 20 during each tracking control in the second pass.

[0088] Specifically, it operates as follows: As shown in Figure 13, in the first tracking control of the first pass, in shot 1, the beam is irradiated to the lower left pixel of each sub-irradiation area 29 using bitmap A, and in shot 2, the same pixel 36 is irradiated with the same beam as in shot 1 using bitmap C. The shot position of the multi-beam 20 for each shot during each tracking control is adjusted by beam deflection by the sub-deflector 209. Then, the tracking is reset after these two shots.

[0089] Similarly, in the second tracking control of the first pass, in shot 3, bitmap A is used to illuminate the lower right pixel of each sub-illumination area 29 with a different beam than in shots 1 and 2, and in shot 4, bitmap C is used to illuminate the same pixel 36 with the same beam as in shot 3. Then, after these two shots, the tracking is reset.

[0090] Similarly, in the third tracking control of the first pass, in shot 5, bitmap A is used to illuminate the upper left pixel of each sub-illumination area 29 with a different beam than in shots 1-4, and in shot 6, bitmap C is used to illuminate the same pixel 36 with the same beam as in shot 5. Then, after these two shots, the tracking is reset.

[0091] Similarly, in the fourth tracking control of the first pass, in shot 7, bitmap A is used to illuminate the upper right pixel of each sub-illumination area 29 with a different beam than in shots 1-6, and in shot 8, bitmap C is used to illuminate the same pixel 36 with the same beam as in shot 7. Then, the tracking is reset after these two shots.

[0092] With the above steps, the drawing of all pixels 36 within the rectangular region 35 in the first pass is completed.

[0093] Next, as shown in Figure 14, in the first tracking control of the second pass, in shot 1, the beam is irradiated to the lower left pixel of each sub-irradiation area 29 using bitmap B, and in shot 2, the same pixel 36 is irradiated with the same beam as in shot 1 using bitmap D. The shot position of the multi-beam 20 for each shot during each tracking control is adjusted by beam deflection by the sub-deflector 209. Then, the tracking is reset after these two shots.

[0094] Similarly, in the second tracking control of the second pass, in shot 3, bitmap B is used to illuminate the lower right pixel of each sub-irradiation area 29 with a different beam than in shots 1 and 2, and in shot 4, bitmap D is used to illuminate the same pixel 36 with the same beam as in shot 3. Then, after these two shots, the tracking is reset.

[0095] Similarly, in the third tracking control of the second pass, in shot 5, bitmap B is used to illuminate the upper left pixel of each sub-irradiation area 29 with a different beam than in shots 1-4, and in shot 6, bitmap D is used to illuminate the same pixel 36 with the same beam as in shot 5. Then, after these two shots, the tracking is reset.

[0096] Similarly, in the fourth tracking control of the second pass, in shot 7, bitmap B is used to illuminate the upper right pixel of each sub-irradiation area 29 with a different beam than in shots 1-6, and in shot 8, bitmap D is used to illuminate the same pixel 36 with the same beam as in shot 7. Then, after these two shots, the tracking is reset.

[0097] With the above steps, the drawing of all pixels 36 within the rectangular region 35 in the second pass is completed. By continuing the drawing in the same manner, the entirety of the stripe regions 32-1, 32-2, 32-3, and 32-4 can be drawn. By drawing similarly for each stripe region, the drawing of the entire drawing region 30 of sample 101 is completed.

[0098] It is preferable, but not limited to, to perform the first pass drawing (double drawing) and the second pass drawing (double drawing) consecutively for each stripe area 32 (performing quadruple drawing). It is also acceptable to perform the drawing of multiple stripe areas in the second pass drawing area 30 after completing the drawing of multiple stripe areas in the first pass drawing area 30.

[0099] In the modified example 2 of Embodiment 1, the tracking timing and beam differ for the same pixel in two of the four bitmaps, but the same pixel in the remaining two bitmaps is drawn with the same beam during the same tracking control. Therefore, the effects of tracking deflection error and beam array distortion can be reduced. Therefore, grayscale error can be reduced.

[0100] Next, a modified example 3 of Embodiment 1 will be described. The bitmap creation process (S102) in Modification Example 3 is the same as in Modification Example 2. As shown in Figure 11, the bitmap creation unit 50 creates four bitmaps (dosemaps) A, B, C, and D, which are offset from each other by a size of 1 / 4 of the size of the pixels 36.

[0101] As part of the drawing sequence setting step (S104) in the modified example 3, the drawing control unit 72 sets the drawing sequence.

[0102] Figure 15 shows a part of an example of a drawing sequence in Modification 3 of Embodiment 1. Figure 16 shows the remainder of an example of a drawing sequence in Modification 3 of Embodiment 1. The examples in Figures 15 and 16 show, for example, the use of a 2x2 multi-beam 20. The examples in Figures 15 and 16 show a case where a sub-irradiation area 29 enclosed by the beam pitch size on the surface of the sample 101 is composed of 2x2 pixels 36. Each stripe area 32-1, 32-2, 32-3, 32-4 is divided into multiple rectangular areas 35 of the same size as the irradiation area 34. Therefore, each rectangular area 35 contains 4x4 pixels 36. The examples in Figures 15 and 16 show a case where, for example, two shots of the multi-beam 20 are performed during one tracking control. Also, during one tracking control, the XY stage 105 moves by m beam pitch (e.g., 1 beam pitch).

[0103] Furthermore, in the drawing sequence of the modified example 3 of Embodiment 1, two or more bitmaps are swapped among multiple bitmaps for each shot during the same tracking control. In the examples of Figures 15 and 16, bitmaps A and C are swapped during the same tracking control. Also, bitmaps B and D are swapped during other identical tracking control periods.

[0104] In the examples in Figures 15 and 16, in the first tracking control, bitmap A is used first, followed by bitmap C. In the second tracking control, bitmap B is used first, followed by bitmap D. This process is repeated thereafter. The order of the bitmaps is not limited to this. In addition to the order A, C, B, D, ..., the order C, A, B, D, ... is also acceptable. For example, the order C, A, D, B, ... is also acceptable. For example, the order B, D, A, C, ... is also acceptable. For example, the order D, B, A, C, ... is also acceptable. For example, the order D, B, C, A, ... is also acceptable. In one of two consecutive tracking control operations, for example, bitmaps A and C should be swapped, and in the other operation, for example, bitmaps B and D should be swapped.

[0105] Note that while Figures 15 and 16 illustrate the case where bitmaps are divided into two sets, bitmaps A and C and bitmaps B and D, this is not the only example. For example, the bitmaps could be divided into two sets, bitmaps A and B and bitmaps C and D. Similarly, the bitmaps could be divided into two sets, bitmaps A and D and bitmaps B and C.

[0106] Furthermore, within each sub-illumination area 29, a drawing sequence is set to draw each pixel in the order of, for example, bottom left, bottom right, top left, and top right. The order in which pixels are drawn is not limited to this. The order of the 2x2 pixels may be different. For example, it could be top left, top right, bottom left, and bottom right.

[0107] In the drawing process (S106) of the modified example 3, first, the drawing data processing unit 70 rearranges the irradiation time data in shot order according to the set drawing sequence. The irradiation time data is stored in the storage device 142. Then, the transfer processing unit 74 transfers the irradiation time data from the storage device 142 to the deflection control circuit 130 in shot order.

[0108] Then, based on multiple bitmaps A, B, C, D, the drawing mechanism 150 draws pixels 36 of two or more stripe regions 32-1, 32-3 (32-2, 32-4) indicated by the data of two or more bitmaps A, C (B, D) among the data of multiple bitmaps A, B, C, D, during one of the multiple tracking controls which deflects the multibeam 20 to follow the movement of the XY stage 105 on which the sample 101 is placed, using multiple shots of the same beam of the multibeam 20.

[0109] In other words, in the modified example 3 of Embodiment 1, the drawing mechanism 150 draws pixels 36 of two or more stripe regions 32-1, 32-3 represented by the data of two or more bitmaps A, B, C, and D, among the data of multiple bitmaps A, B, C, and D, using multiple shots of the same beam of the multibeam 20 during the k-th tracking control (where k is a natural number), and draws pixels 36 of one or more stripe regions 32-2, 32-4 represented by the data of one or more other bitmaps B, D, among the data of multiple bitmaps A, B, C, and D, using one or more shots of the same beam of the multibeam 20 during the (k+1)-th tracking control.

[0110] Furthermore, in the modified example 3 of Embodiment 1, the drawing mechanism 150 draws the same pixels 36 in the stripe regions 32-1, 32-3 (32-2, 32-4) represented by multiple bitmaps A, C (B, D) using multiple shots of the same beam of the multi-beam 20 during each tracking control. In the example shown in Figures 15 and 16, the drawing mechanism 150 draws the same pixels 36 in the stripe regions 32-1, 32-3 represented by two bitmaps A, C using two shots of the same beam of the multi-beam 20 during the k-th tracking control. Also, during the (k+1)-th tracking control, the drawing mechanism 150 draws the same pixels 36 in the stripe regions 32-2, 32-4 represented by two bitmaps B, D using two shots of the same beam of the multi-beam 20.

[0111] Specifically, it operates as follows: As shown in Figure 15, in the first tracking control, in shot 1, the beam is irradiated to the lower left pixel of each sub-irradiation area 29 using bitmap A, and in shot 2, the same pixel 36 is irradiated with the same beam as in shot 1 using bitmap C. The shot position of the multi-beam 20 for each shot during each tracking control is adjusted by beam deflection by the sub-deflector 209. Then, after these two shots, the tracking is reset.

[0112] Similarly, in the second tracking control, in shot 3, bitmap B is used to illuminate the lower left pixel of each sub-irradiation area 29 with a different beam than in shots 1 and 2, and in shot 4, bitmap D is used to illuminate the same pixel 36 with the same beam as in shot 3. Then, after these two shots, the tracking is reset.

[0113] Similarly, in the third tracking control, in shot 5, bitmap A is used to illuminate the lower right pixel of each sub-irradiation area 29 with a different beam than in shots 1-4, and in shot 6, bitmap C is used to illuminate the same pixel 36 with the same beam as in shot 5. Then, after these two shots, the tracking is reset.

[0114] Similarly, in the fourth tracking control, in shot 7, bitmap B is used to illuminate the lower right pixel of each sub-irradiation area 29 with a different beam than in shots 1-6, and in shot 8, bitmap D is used to illuminate the same pixel 36 with the same beam as in shot 7. Then, after these two shots, the tracking is reset.

[0115] Similarly, in the fifth tracking control, in shot 9, bitmap A is used to illuminate the upper left pixel of each sub-irradiation area 29 with a different beam than in shots 1-8, and in shot 10, bitmap C is used to illuminate the same pixel 36 with the same beam as in shot 9. Then, after these two shots, the tracking is reset.

[0116] Similarly, in the sixth tracking control, in shot 11, bitmap B is used to illuminate the upper left pixel of each sub-irradiation area 29 with a different beam than in shots 1-10, and in shot 12, bitmap D is used to illuminate the same pixel 36 with the same beam as in shot 11. Then, after these two shots, the tracking is reset.

[0117] Similarly, in the seventh tracking control, shot 13 uses bitmap A to illuminate the upper right pixel of each sub-irradiation area 29 with a different beam than in shots 1-12, and shot 14 uses bitmap C to illuminate the same pixel 36 with the same beam as in shot 13. Then, after these two shots, the tracking is reset.

[0118] Similarly, in the eighth tracking control, shot 15 uses bitmap B to illuminate the upper right pixel of each sub-irradiation area 29 with a different beam than shots 1-14, and shot 16 uses bitmap D to illuminate the same pixel 36 with the same beam as shot 15. Then, after these two shots, the tracking is reset.

[0119] With the above steps, the drawing of all pixels 36 within the rectangular region 35 is completed. By continuing the drawing process in the same manner, the entirety of the stripe regions 32-1, 32-2, 32-3, and 32-4 can be drawn. By drawing similarly for each stripe region, the drawing of the entire drawing region 30 of sample 101 is completed.

[0120] In Modification 3 of Embodiment 1, the same pixels of two of the four bitmaps are drawn with the same beam during the same tracking control. Furthermore, the same pixels of the remaining two bitmaps can be drawn with adjacent beams during adjacent tracking control. Thus, grayscale errors can be reduced.

[0121] The example above described the case where two bitmaps are shifted in the y-direction, but this is not the only example.

[0122] Figure 17 shows another example of multiple bitmaps in Embodiment 1. In the example in Figure 17, two bitmaps A and B are shown. The two bitmaps A and B are created with a size of half the size of pixel 36 and offset from each other in the x and y directions. In this case as well, grayscale errors can be reduced. Alternatively, the two bitmaps A and B may be created with a size of half the size of pixel 36 and offset from each other in the x direction.

[0123] Figure 18 shows an example of the relationship between dose amount and position when bitmap shifting is performed in Embodiment 1. In Figure 18, the vertical axis shows the dose amount, and the horizontal axis shows the position in the y-direction. The example in Figure 18 shows the case where two bitmaps are used. The two bitmaps are created by shifting them in the y-direction by half the size of pixel 36. At the edge of the pattern, bitmap A draws with 1 / 4 dose on the pixel at the edge position and 1 / 2 dose on the pixel to its right, while bitmap B, which is shifted to the right (y-direction) by half the size of pixel 36, draws with 1 / 2 dose on the pixel at the edge position and 1 / 2 dose on the pixel to its right. Since the total dose of bitmaps A and B is applied to the edge, the smallest unit of gradation value representing the edge can be subdivided from the pixel size to, in effect, half the size of the pixel size. Because it can be subdivided, the resolution can be increased, and thus the gray error can be reduced. However, grayscale error reduction is only possible if the actual overlays of the bitmaps are not misaligned or if the misalignment is small. If the overlays of the bitmaps are misaligned, the target grayscale error reduction effect cannot be achieved. Even if there is no overlay misalignment in the design, if the actual beam irradiation position is misaligned, the grayscale error reduction effect cannot be achieved.

[0124] Figure 19 shows an example of the relationship between edge displacement and position in Embodiment 1. In Figure 19, the vertical axis shows the edge displacement, and the horizontal axis shows the position in the y-direction. Graph a shows the case where the actual beam irradiation position is shifted by 2 nm. Graph b shows the case where the actual beam irradiation position is shifted by 1 nm. Graph c shows the case where there is no shift in the actual beam irradiation position (0 nm). As shown in Figure 19, it can be seen that the amount of edge shift increases when the actual beam irradiation position is shifted from the design pixel position shown in the bitmap.

[0125] As described above, according to Embodiment 1, in multi-beam lithography using the bitmap shift method, the discrepancy between the designed pixel position and the actual beam position can be reduced. Therefore, the amount of edge misalignment can be reduced.

[0126] The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples.

[0127] 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.

[0128] Furthermore, all multi-charged particle beam lithography apparatuses, multi-charged particle beam lithography methods, and programs 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]

[0129] 20 Multibeam 22 holes 24 control electrodes 25 Passing hole 26 Counter electrode 30 drawing area 36 pixels 29 Sub-irradiation area 32 Stripe Area 34 Irradiation area 35 rectangular area 41 Control circuits 50 Bitmap Creation Section 70 Drawing Data Processing Unit 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 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 source 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 process of creating bitmap data in which each drawing area of ​​a sample is composed of multiple pixels consisting of regions divided into a mesh, and for each of the multiple drawing areas offset by less than or equal to the size of each pixel, a value is defined that depends on the dose amount of each pixel. After tracking control to deflect the multi-charged particle beam in accordance with the movement of the stage on which the sample is placed, the deflection amount is reset in a cycle that is repeated, and during one tracking control, based on two or more bitmap data from the plurality of bitmap data, pixels in the drawing area corresponding to the two or more bitmap data are drawn in multiple shots of the same beam of the multi-charged particle beam. A multi-charged particle beam lithography method characterized by comprising the following features.

2. In the drawing process described above, The multi-charged particle beam drawing method according to claim 1, characterized in that during the aforementioned single tracking control, the same pixels of the drawing area corresponding to each of the two or more bitmap data are drawn.

3. In the drawing process described above, The multi-charged particle beam drawing method according to claim 1, characterized in that during the aforementioned single tracking control, different pixels in the drawing areas corresponding to the two or more bitmap data are drawn.

4. In the drawing process described above, During the first tracking control, which is one tracking control as described above, two or more bitmap data, which are part of the bitmap data of the multiple stripe regions, are drawn on two or more pixels of the stripe regions with the first beam of the multi-charged particle beam. The multi-charged particle beam drawing method according to claims 1 to 3, characterized in that, during a second tracking control which is a single tracking control performed before or after the first tracking control, pixels of one or more stripe regions are drawn with the first beam based on one or more bitmap data which are other parts of the bitmap data of the plurality of stripe regions.

5. The plurality of drawing regions are divided in a direction linearly independent of the movement direction of the stage, and each region has a plurality of stripe regions with an offset less than or equal to the size of the pixel region. The multi-charged particle beam drawing method according to claim 4, wherein the first tracking control and the second tracking control are provided for each drawing of at least one of the plurality of stripe regions.

6. The process involves creating multiple bitmap data sets, each consisting of multiple pixels formed by dividing the sample's drawing area into a mesh-like region, and for each of the multiple drawing areas offset by less than or equal to the size of each pixel, a value is defined that depends on the dose amount of each pixel. The process of storing the created bitmap data in a memory device, The process involves reading the plurality of bitmap data from the storage device, performing tracking control to deflect the multi-charged particle beam to follow the movement of the stage on which the sample is placed, and then repeating a cycle of resetting the deflection amount, and during one tracking control, controlling the drawing mechanism to draw pixels in the drawing area corresponding to the two or more bitmap data based on two or more of the plurality of bitmap data in multiple shots of the same beam of the multi-charged particle beam, respectively. A program that causes a computer to execute something.

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