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

Abstract

This invention provides a method that can reduce the degradation of drawing accuracy caused by fluctuations in beam current, etc., using methods other than correction. [Configuration] One aspect of the present invention is a multi-charged particle beam drawing method, characterized by comprising the steps of: dividing a multi-charged particle beam into an array and setting up a plurality of beam groups to irradiate a specific area of ​​a part of the drawing area of ​​a sample; drawing a pattern in an area other than the specific area of ​​the drawing area of ​​a sample while simultaneously irradiating with the multi-charged particle beams; and drawing a pattern in a specific area of ​​a sample with the beams of each of the plurality of beam groups, while staggering the irradiation timing for each beam group.

Description

Technical Field

[0001] One aspect of the present invention relates to a multi-charged particle beam drawing method and a multi-charged particle beam drawing apparatus, and for example, relates to a technique for correcting positional deviation occurring on a substrate surface in multi-beam drawing.

Background Art

[0002] Lithography technology, which is responsible for the progress of miniaturization of semiconductor devices, is an extremely important process for generating patterns uniquely among semiconductor manufacturing processes. In recent years, with the high integration of LSIs, the circuit linewidth required for semiconductor devices has been miniaturized year by year. Here, electron beam (electron beam) drawing technology has inherently excellent resolution, and drawing on a wafer or the like using an electron beam has been performed.

[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, many 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 and irradiated to a desired position on the sample.

[0004] Here, in multi-beam drawing, drawing can be performed at high speed by using a large number of beams. At that time, since drawing is performed while individually blanking a large number of beams, the larger the total current amount of the entire multi-beam used, the so-called blur amount of the beam due to the Coulomb effect or the like, the shift of the irradiation position of the beam due to charging in the column, or the shape deformation of the beam array may occur. These deteriorations in drawing accuracy have a large influence on the dimensions and positions of the pattern because the error amount is different for each edge of the pattern when the current fluctuation during drawing is large. Further, when there are density differences in the drawn pattern, in a locally high-density or low-density region, the drawing accuracy is likely to deteriorate at the boundary portion of the region.

[0005] Here, a method is disclosed for performing position correction on the entire multibeam system individually for each shot, based on parameters related to each shot (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2021-132065 [Overview of the project] [Problems that the invention aims to solve]

[0007] One aspect of the present invention provides a method and apparatus capable of reducing the deterioration of drawing accuracy caused by fluctuations in beam current, etc., by means other than correction. [Means for solving the problem]

[0008] A multi-charged particle beam lithography method according to one aspect of the present invention is: The process involves setting up multiple beam groups by array-dividing a multi-charged particle beam to irradiate a specific area within the patterning region of the sample, A process of drawing a pattern in areas of a sample other than a specific area of ​​the drawing region while simultaneously irradiating it with multiple charged particle beams, The process involves drawing a pattern on a specific area of ​​a sample using the beams of each beam group, while staggering the irradiation timing for each beam group of multiple beam groups. It is characterized by having the following features.

[0009] Furthermore, it is preferable that a specific region be drawn using each beam group, while changing the stage path for each beam group, which indicates the drawing process during a single stage movement in a direction corresponding to the drawing direction of the stage on which the sample is placed.

[0010] Alternatively, a particular region may be drawn using at least some of the beam groups within the plurality of beam groups during the same stage pass, which represents a drawing process during a single stage movement in a direction corresponding to the drawing direction of the stage on which the sample is placed.

[0011] Furthermore, it is preferable to further include a step of identifying the specific area from within the drawing area.

[0012] Furthermore, the system includes a step of determining whether the area density of each predetermined rectangular region within the drawing area of ​​the sample is equal to or greater than an area density threshold. It is preferable that a rectangular region whose area density is equal to or greater than the area density threshold is identified as a specific region.

[0013] Alternatively, and / or, for each predetermined rectangular region of the sample drawing area, the process includes determining whether the rate of change of the area density of that rectangular region relative to the average area density is greater than or equal to a rate of change threshold, It is preferable that a rectangular region in which the rate of change of area density is greater than or equal to a rate of change threshold is identified as a specific region.

[0014] Alternatively, and / or, for each predetermined rectangular region of the drawing area of ​​the sample, the method includes a step of determining whether the proportion of array pitch patterns such that the beam pitch and pattern pitch of the multi-charged particle beam are in an integer multiple or integer fraction relationship including matching is greater than or equal to a pattern proportion threshold, It is preferable that a rectangular region where the proportion of array pitch patterns that are integer multiples of each other is greater than or equal to a pattern proportion threshold is identified as a specific region.

[0015] A multi-charged particle beam lithography apparatus according to one aspect of the present invention is: A splitting unit divides a multi-charged particle beam into multiple beam groups, each consisting of at least one beam that irradiates a specific area within the patterning region of the sample. A drawing mechanism that uses all or part of the multi-charged particle beam to draw a pattern on the sample, Equipped with, The drawing mechanism is, While simultaneously irradiating a multi-charged particle beam, a pattern is drawn on an area other than a specific area in the drawing area of the sample. While shifting the irradiation timing for each beam group of a plurality of beam groups, a pattern is drawn on the specific area of the sample with at least one beam of each beam group. It is characterized by the above.

[0016] The multi-charged particle beam drawing method according to another aspect of the present invention is as follows. For an area other than a specific area in a part of the drawing area of the sample, with the number of multi-charged particle beams used for drawing as the reference beam number, a step of drawing a pattern on the area other than the specific area. For the specific area, using a multi-charged particle beam with the number of multi-charged particle beams used for the drawing reduced from the reference beam number and the number of shots increased from the reference number, a step of drawing a pattern on the specific area. It is characterized by including the above.

[0017] Also, for an area other than the specific area, using a multi-charged particle beam with the number of irradiation times as the reference number of times, a step of drawing the pattern on the area other than the specific area. For the specific area, using a multi-charged particle beam with the number of shots increased from the reference number of times, a step of drawing a pattern on the specific area. It is preferable to include the above.

[0018] Also, it is preferable to narrow the width of the stripe and the beam array width obtained by dividing the area including the specific area into the drawing area in one stage pass in a direction linearly independent of the moving direction of the stage.

Effect of the Invention

[0019] According to one aspect of the present invention, deterioration of drawing accuracy caused by fluctuations in beam current amount, etc. can be reduced by a method other than correction.

Brief Description of the Drawings

[0020] [Figure 1]This is a conceptual diagram showing an example of the configuration of the drawing device in Embodiment 1. [Figure 2] This is a conceptual diagram showing an example of the configuration of a molded aperture array substrate in Embodiment 1. [Figure 3] This is a cross-sectional view showing an example of the configuration of the blanking aperture array mechanism in Embodiment 1. [Figure 4] This is a conceptual diagram illustrating an example of the drawing operation in Embodiment 1. [Figure 5] This figure shows an example of the multi-beam irradiation area and the pixels to be drawn in Embodiment 1. [Figure 6] This figure illustrates an example of multibeam lithography operation in Embodiment 1. [Figure 7] This figure shows an example of beam pitch and pattern pitch in Embodiment 1. [Figure 8] This figure shows another example of beam pitch and pattern pitch in Embodiment 1. [Figure 9] This figure shows another example of beam pitch and pattern pitch in Embodiment 1. [Figure 10] This figure shows an example of a specific region in Embodiment 1. [Figure 11] This is a flowchart illustrating an example of the main steps of the drawing method in Embodiment 1. [Figure 12] This figure shows an example of a multi-beam configuration and an example of a beam array region in Embodiment 1. [Figure 13] This figure shows an example of the configuration of a multi-beam beam group and an example of the beam array region in Embodiment 1. [Figure 14] This figure shows another example of the configuration of a multi-beam beam group in Embodiment 1, and an example of a beam array region. [Figure 15] This figure illustrates an example of segmented drawing when drawing a striped area that includes a specific region in Embodiment 1. [Figure 16]This figure illustrates another example of segmented drawing when drawing a striped area that includes a specific region in Embodiment 1. [Figure 17] This is a conceptual diagram showing an example of the configuration of the drawing device in Embodiment 2. [Figure 18] This is a flowchart illustrating an example of the drawing method in Embodiment 2. [Figure 19] This figure shows an example of a specific region, a beam array region, and a stripe region in a modified example of Embodiment 2. [Modes for carrying out the invention]

[0021] 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.

[0022] Embodiment 1. Figure 1 is a conceptual diagram showing an example of 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 gun 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] The control computer 110 contains a Rice Rise processing unit 50, a Shot Data Generation Unit 52, a Parameter Calculation Unit 54, a Determination Unit 56, a Specific Area Identification Unit 58, a Beam Group Setting Unit 60, a Drawing Control Unit 72, and a Transfer Processing Unit 74. Each of the "~ section," such as the Rice Rise Processing Unit 50, Shot Data Generation Unit 52, Parameter Calculation Unit 54, Determination Unit 56, Specific Area Identification Unit 58, Beam Group Setting Unit 60, Drawing Control Unit 72, and Transfer Processing Unit 74, has a processing circuit. Such processing circuits include, for example, electrical circuits, computers, processors, circuit boards, quantum circuits, or semiconductor devices. Each of the "~ section" may use a common processing circuit (the same processing circuit) or different processing circuits (separate processing circuits). Information input to and output from the Rice Rise Processing Unit 50, Shot Data Generation Unit 52, Parameter Calculation Unit 54, Determination Unit 56, Specific Area Identification Unit 58, Beam Group Setting Unit 60, Drawing Control Unit 72, and Transfer Processing Unit 74, as well as information being calculated, is stored in the memory 112 each time.

[0027] The drawing operation of the drawing device 100 is controlled by the drawing control unit 72. In other words, the drawing control unit 72 (an example of a control circuit) controls the drawing mechanism 150. 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.

[0028] 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 coordinates of each vertex are defined in the order in which the graphic is formed. Alternatively, for each graphic pattern, for example, the graphic code, coordinates, and size are defined.

[0029] Here, Figure 1 shows the configuration necessary to explain Embodiment 1. The drawing device 100 may also have other configurations that are normally necessary.

[0030] Figure 2 is a conceptual diagram showing an example of 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 in the horizontal and vertical (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 to form a multi-beam 20. In other words, the molded aperture array substrate 203 forms a multi-beam 20.

[0031] Figure 3 is a cross-sectional view showing an example of 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.

[0032] 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.

[0033] 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-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).

[0034] 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 the 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, while the XY stage 105 is moving continuously, the main deflector 208 performs tracking control so that the beam irradiation position 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.

[0035] 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 multi-beam 20 irradiation in the y-direction.

[0036] Furthermore, while the example in Figure 4 shows the case where the stage moves only once (1 pass) to draw each stripe, multiple drawing can also be performed by moving the stage multiple times for each stripe. In that case, for example, in the case of multiple drawing of N passes, it is preferable to shift the position in the y direction by 1 / N size of the width of the stripe area 32 for each pass. The multiplicity is not limited to 2, and may be 3 or more.

[0037] Furthermore, the positional shift described above is not limited to the y-direction, but may also be applied to the x-direction.

[0038] Furthermore, for multiplex drawing, it is also preferable to perform multiplex drawing (multiple drawing within a path) in which each position is drawn multiple times while the stage moves through each stripe once. Next, an example of drawing operation will be described.

[0039] First, the XY stage 105 is moved to adjust the position of the illumination area 34 of the multi-beam 20 to the left edge of the first stripe area 32 of the first stripe layer, or even further to the left. Then, when drawing the first stripe area 32, the drawing is advanced 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.

[0040] After the first stripe area 32 has finished drawing, the stage position is moved in the -y direction by the width of the stripe area 32. This shifts the drawn stripe area 32 in the y direction by the width of the stripe area 32.

[0041] Next, the illumination 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 process is repeated thereafter to draw each stripe area 32.

[0042] Furthermore, while Figure 4 shows an example where each stripe region 32 is drawn in the same direction, this is not the only option. For example, for a stripe region 32 to be drawn after a 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.

[0043] Furthermore, in a single shot, multiple shot patterns, up to the same number as each hole 22, are formed at once by the multi-beam that passes through each hole 22 of the molded aperture array substrate 203.

[0044] Figure 5 shows an example of the multi-beam irradiation area and the pixels to be drawn 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-beam 20. Each of these mesh areas becomes the pixels 36 to be drawn (beam irradiation unit area, irradiation position). The size of the pixels to be drawn 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 of 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-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 512x512-row multibeam is shown as an 8x8-row multibeam. Within the irradiation area 34, multiple pixels 28 (beam drawing positions) that can be irradiated in one shot of the multibeam 20 are shown. The pitch between adjacent pixels 28 becomes the inter-beam pitch of the multibeam. A rectangular area enclosed by the size of the inter-beam pitch in the x and y directions constitutes one sub-irradiation area 29 (pitch cell area). In the example in Figure 5, each sub-irradiation area 29 is shown as being composed of, for example, 4x4 pixels.

[0045] Figure 6 is a diagram illustrating an example of multi-beam lithography operation in Embodiment 1. The example in Figure 6 shows the case where each sub-irradiation area 29 is lithographed with four different beams. Furthermore, the example in Figure 6 shows a lithography operation in which the XY stage 105 moves continuously at a speed that moves a distance L equivalent to 8 beam pitches while lithographing 1 / 4 (1 out of the number of beams used for irradiation) of each sub-irradiation area 29. In the lithography operation shown in the example in Figure 6, for example, while the XY stage 105 moves a distance L equivalent to 8 beam pitches, the sub-deflector 209 sequentially shifts the irradiation position (pixel 36) and lithographs (exposes) four different pixels 36 within the same sub-irradiation area 29 by firing four shots of the multi-beam 20 in a shot cycle T. While the four pixels 36 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 the stripe area 32 is being drawn, 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 middle section of Figure 4, and drawing is performed.

[0046] As mentioned above, in multi-beam plotting, the total current changes during plotting because multiple beams are blanked individually while plotting.

[0047] Figure 7 shows an example of beam pitch and pattern pitch in Embodiment 1. Figure 8 shows another example of beam pitch and pattern pitch in Embodiment 1. Figure 9 shows another example of beam pitch and pattern pitch in Embodiment 1. Figure 7 shows an example where the beam pitch of the multi-beam 20 and the pattern pitch of the pattern 42 do not match. Generally, in the layout of the chip pattern being drawn, as shown in Figure 7, the pattern pitches are not equal, or the beam pitch of the multi-beam 20 and the pattern pitch of the pattern 42 are different, so the beam pitch of the multi-beam 20 and the pattern pitch of the pattern 42 often do not match overall within the irradiation area 34 (beam array area). When the beam pitch of the multi-beam 20 and the pattern pitch of the pattern 42 do not match in this way, the change in the number of blanking beams per shot is small. Therefore, the change in the total current is also small.

[0048] On the other hand, the example in Figure 8 shows an example where the beam pitch of the multi-beam 20 and the pattern pitch of pattern 42 match. The example in Figure 8 shows an example of a shot where all beams are beam-ON. In the case shown in Figure 8, in the next shot, it is possible that all beams will be beam-OFF, as shown in Figure 9. Thus, when the beam pitch of the multi-beam 20 and the pattern pitch of pattern 42 match, or when the beam pitch of the multi-beam 20 and the pattern pitch of pattern 42 are integer multiples, the change in the number of blanking beams per shot becomes very large. Therefore, the change in the total current also becomes large.

[0049] As shown in Figures 8 and 9, when the beam pitch and pattern pitch are in an integer multiple relationship including coincidence, focus shift of the multi-beam 20, degradation of beam resolution due to the Coulomb effect (so-called blurring), and / or individual positional shifts of multiple patterns drawn within the beam array region may occur.

[0050] Figure 10 shows an example of a specific region in Embodiment 1. In the example in Figure 10, it is shown that within the drawing area 30 of the drawn chip pattern, there is a specific region 40 in which the proportion of patterns where the beam pitch and pattern pitch are in an integer multiple relationship including matching is particularly high. In addition to the cases described above, the specific region 40 includes areas with a uniquely high pattern density (area density) compared to the surrounding areas. When rendering such a specific region 40 with a uniquely high pattern density, focus shifts of the multi-beam 20 and degradation of beam resolution (so-called blurring) due to the Coulomb effect are likely to occur. Other specific regions 40 may include areas where the pattern density fluctuates significantly from the surrounding area. When plotting specific regions 40 with large pattern density fluctuations, uniform positional shifts may occur among the multiple patterns plotted within the beam array region.

[0051] Therefore, in Embodiment 1, the presence or absence of such a specific region 40 is determined, and when drawing the specific region 40, the drawing method is changed from that used when drawing other regions, thereby reducing the effects of the aforementioned focus shift and other issues by a method other than correction. This will be explained in detail below.

[0052] Figure 11 is a flowchart showing an example of the main steps of the drawing method in Embodiment 1. In Figure 11, the drawing method in Embodiment 1 performs a series of steps: rasterization (S102), shot data generation (S104), determination parameter calculation (S110), determination (S120), specific area identification (S124), beam group setting (S126), normal drawing (S130), segmented drawing (S132), and determination (S140).

[0053] As part of the rasterization process (S102), the rasterization processing unit 50 reads chip pattern data (drawing data) from the storage device 140, for example, for each stripe area 32, and performs rasterization processing. Specifically, it calculates the pattern density (pattern area density) for each pixel 36.

[0054] As part of the shot data generation process (S104), the shot data generation unit 52 first calculates the irradiation amount D to irradiate each pixel 36. The irradiation amount D can be calculated, for example, by multiplying a preset 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 density ρ' (pattern area density) of the pattern placed within each proximity mesh area is calculated.

[0055] 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 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.

[0056] The shot data generation unit 52 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) in which irradiation time data (shot data) for each pixel 36 is defined.

[0057] When performing multiplex drawing, a dose map (actually an irradiation time map) is created for each multiplex drawing process. In other words, a stripe layer is created for each multiplex drawing, and a dose map (actually an irradiation time map) is created for each stripe layer. The created irradiation time data is stored in the storage device 142 in shot order.

[0058] As a determination parameter calculation step (S110), the parameter calculation unit 54 calculates parameters to be used for determining a specific region 40 using drawing data, rasterized data, and / or shot data. At least one of the following parameters is used: the proportion S of patterns in which the beam pitch and pattern pitch are in an integer multiple relationship including coincidence; the area density ρ of the pattern; and the rate of variation of the area density of the pattern. The area density ρ of the pattern and the rate of variation of the area density of the pattern can be calculated efficiently, for example, using rasterized data. The proportion S of patterns in which the beam pitch and pattern pitch are in an integer multiple relationship including coincidence can be calculated efficiently, for example, using drawing data or shot data.

[0059] The rate of variation Δρ of the pattern area density is calculated, for example, by determining the rate of variation of the pattern area density in the target area from the average value of the pattern area density within the stripe area 32. Alternatively, for example, the rate of variation of the pattern area density in the target area is calculated from the average value of the pattern area density within the drawing area 30, which is the chip area. In this case, since the drawing data for each stripe area 32 alone is insufficient for the calculation, the drawing data for the entire chip area is read.

[0060] Furthermore, a rectangular region 35 of the same size as the irradiation region 34 (beam array region) of the multi-beam 20 is used to calculate these parameters. Specifically, as shown in the lower part of Figure 4, the stripe region 32 is divided into multiple rectangular regions 35 (processing regions) of the same size as the irradiation region 34 (beam array region), and these parameters are calculated for each rectangular region 35.

[0061] Furthermore, the processing area for calculating parameters is preferably designed to match the shape and size of the beam array area. If the beam array area is not rectangular (for example, circular, trapezoidal, parallelogram, or other shapes), the processing area for calculating parameters should also be designed to match that shape.

[0062] In the determination step (S120), the determination unit 56 determines whether the calculated parameter is equal to or greater than a threshold. Specifically, it operates as follows. The determination unit 56 determines, for each predetermined rectangular region 35 of the drawing area of ​​the sample 101 (here, for example, the stripe region 32), whether the ratio S of the array pitch patterns where the beam pitch and pattern pitch of the multibeam 20 are in an integer multiple or integer fraction relationship, including matching, is greater than or equal to a threshold Th1 (pattern ratio threshold). For example, the determination unit 56 determines, for each rectangular region 35 of the drawing area of ​​the sample 101 (here, for example, the stripe region 32), which is the same size as the area of ​​the beam array in which the multibeams 20 are arranged, whether the ratio S of the array pitch patterns where the beam pitch and pattern pitch of the multibeam 20 are in an integer multiple or integer fraction relationship, including matching, is greater than or equal to a threshold Th1 (pattern ratio threshold). It is preferable to use a value of 15% or more as the threshold Th1. More preferably, it is preferable to use a value in the range of 20 to 30%. Furthermore, the determination unit 56 determines whether the area density ρ is equal to or greater than the threshold Th2 (area density threshold) for each predetermined rectangular region 35 of the drawing area of ​​the sample 101 (in this case, for example, the stripe region 32). For example, the determination unit 56 determines whether the area density ρ is equal to or greater than the threshold Th2 (area density threshold) for each rectangular region 35 of the drawing area of ​​the sample 101 (in this case, for example, the stripe region 32) that is the same size as the area of ​​the beam array in which the multi-beams 20 are arranged. It is preferable to use a value of 70% or more as the threshold Th2. More preferably, it is preferable to use a value of 80% or more. Furthermore, the determination unit 56 determines, for each predetermined rectangular region 35 of the drawing area of ​​the sample 101 (in this case, for example, the stripe region 32), whether the rate of variation Δρ of the area density of the rectangular region 35 relative to the average area density is greater than or equal to the threshold Th3 (rate of variation threshold). For example, the determination unit 56 determines, for each rectangular region 35 of the drawing area of ​​the sample 101 (in this case, for example, the stripe region 32) that is the same size as the area of ​​the beam array in which the multibeams 20 are arranged, whether the rate of variation Δρ of the area density of the rectangular region 35 relative to the average area density is greater than or equal to the threshold Th3 (rate of variation threshold). It is preferable to use a value of 15% or more as the threshold Th3. More preferably, it is preferable to use a value in the range of 20 to 30%. If the determination finds that there is at least one rectangular region 35 whose parameters are equal to or greater than the threshold, the process proceeds to the specific region identification step (S124). If the determination finds that there are no rectangular regions 35 whose parameters are equal to or greater than the threshold, the process proceeds to the normal drawing step (S130).

[0063] As a specific area identification step (S124), the specific area identification unit 58 identifies a specific area 40 from within the drawing area (in this case, for example, the stripe area 32). Specifically, it operates as follows: The specific area identification unit 58 identifies a rectangular area 35 whose parameters are above a threshold as a specific area 40. More specifically, a rectangular area 35 in which the ratio S of the array pitch pattern, which is an integer multiple including the beam pitch and the pattern pitch, is above a threshold Th1 is identified as a specific area 40. Also, a rectangular area 35 in which the area density ρ is above a threshold Th2 is identified as a specific area 40. Also, a rectangular area 35 in which the area density fluctuation rate Δρ is above a threshold Th3 is identified as a specific area 40. If two or more rectangular areas 35 meet the criteria, each is identified as a specific area 40. It is also possible that in a single rectangular area 35, two or more of the three parameters described above are above their respective thresholds. In such cases, the rectangular area 35 is identified as one of the specific areas 40. Furthermore, the user may pre-specify a specific area range, and regardless of the result of the determination step (S120), an area within the drawing area 30 that is included in the pre-specified range may be further set as a specific area. For example, it is preferable for the user to set an area where a pattern with a thin line width, which is susceptible to the effects of drawing accuracy degradation, is placed as a specific area based on the drawing layout information.

[0064] As a beam group setting step (S126), the beam group setting unit 60 divides the multi-beam 20 into an array and sets up multiple beam groups that irradiate a specific area 40 of a part of the drawing area 30 of the sample 101. In other words, the beam group setting unit 60 divides the multi-beam 20 and sets up multiple beam groups, each consisting of at least one beam that irradiates a specific area 40 of a part of the drawing area 30 of the sample 101.

[0065] Figure 12 shows an example of a multi-beam configuration and an example of a beam array region in Embodiment 1. In the example in Figure 12, a multi-beam 20 composed of, for example, 4x4 beams and its beam array region (irradiation region 34) are shown. In the example in Figure 12, the beam pitch of the multi-beam 20 is shown to be the size of 2 pixels. Therefore, in this case, the sub-irradiation region 29 that each beam can irradiate is composed of, for example, 2x2 pixels. In normal drawing, drawing is carried out while simultaneously irradiating the entire multi-beam 20 composed of 4x4 beams.

[0066] Figure 13 shows an example of the configuration of a multi-beam beam group and an example of the beam array region in Embodiment 1. In the example in Figure 13, for example, a multi-beam 20 composed of 4x4 beams is divided into four beam groups A, B, C, and D. Beam group A is composed of 2x2 beams, starting from the bottommost and leftmost beam of the 4x4 multi-beam 20, with one beam removed in each of the x and y directions. Beam group B is composed of 2x2 beams, starting from the second-to-last beam from the bottom and the first beam from the left of the 4x4 multi-beam 20, with one beam removed in each of the x and y directions. Beam group C is composed of 2x2 beams, starting from the first beam from the bottom and second beam from the left of the 4x4 multi-beam 20, with one beam removed in each of the x and y directions. Beam group D is composed of 2x2 beams, starting from the second beam from the bottom and second beam from the left of the 4x4 multi-beam 20, with one beam removed in each of the x and y directions.

[0067] Figure 14 shows another example of the configuration of a multi-beam beam group in Embodiment 1 and an example of a beam array region. In the example in Figure 14, for example, a multi-beam 20 consisting of 4x4 beams is divided into four beam groups A, B, C, and D. Beam group A consists of a 4x1 beam, which is the first stage from the bottom of the 4x4 multi-beam 20. Beam group B consists of a 4x1 beam, which is the second-to-last beam from the bottom of the 4x4 multi-beam 20. Beam group C consists of a 4x1 beam, which is the third stage from the bottom of the 4x4 multi-beam 20. Beam group D consists of a 4x1 beam, which is the fourth beam from the bottom of the 4x4 multi-beam 20.

[0068] In the normal drawing process (S130), the drawing mechanism 150 draws a pattern on the drawing area (in this case, the stripe area 32) of the sample 101 while simultaneously irradiating it with multiple beams 20. However, it goes without saying that pixels that do not have a pattern and do not need to be irradiated with a beam are not irradiated with the target beam.

[0069] As a segmented drawing process (S132), the drawing mechanism 150 draws a pattern in the area of ​​the drawing region (in this case, the stripe region 32) of the sample 101, excluding the specific region 40, while simultaneously irradiating with the multi-beams 20. The drawing mechanism 150 then draws a pattern in the specific region 40 of the sample 101 with the beams of each beam group, staggering the irradiation timing for each beam group. In other words, for the area of ​​the drawing region (in this case, the stripe region 32) of the sample 101, excluding the specific region 40, the drawing mechanism 150 draws a pattern in the area excluding the specific region 40, using the number of multi-beams 20 used for drawing as the reference number of beams. Furthermore, for the area excluding the specific region 40, the drawing mechanism 150 draws a pattern in the area excluding the specific region 40 using the multi-beams 20 with the number of irradiations as the reference number. In other words, the drawing mechanism 150 uses a multi-beam 20, with the number of beams set to the reference number of beams and the number of shots set to the reference number, to draw a pattern in the area of ​​the drawing region of the sample 101 (in this case, the stripe region 32) other than the specific region 40. The drawing mechanism 150 then draws a pattern on the specific region 40 using a multi-beam 20 with a number of shots increased compared to the standard number of shots. In other words, the drawing mechanism 150 draws a pattern on the specific region 40 of the sample 101 using a multi-beam 20 with a reduced number of multi-beams 20 used for drawing compared to the standard number of beams, and with a number of shots increased compared to the standard number of shots. This will be explained in detail below.

[0070] Figure 15 is a diagram illustrating an example of segmented drawing when drawing a striped area that includes a specific region in Embodiment 1. Figure 16 is a diagram illustrating another example of segmented drawing when drawing a stripe region including a specific area in Embodiment 1. In the examples of Figures 15 and 16, the specific area 40 is drawn using each beam group, changing the drawing path that shows the drawing process during one stage movement in a direction corresponding to the drawing direction (here, the x-direction) of the XY stage 105 on which the sample 101 is placed, specifically, for example, in a parallel direction (e.g., the -x-direction). In the example of Figure 15, the case where the beam group shown in Figure 13 is used is shown as an example. In the example of Figure 16, the case where the beam group shown in Figure 14 is used is shown as an example. Also, in the examples of Figures 15 and 16, the sub-irradiation area 29 that each beam is responsible for consists of 2 × 2 pixels. Therefore, if each beam irradiates one pixel per tracking cycle, the drawing within the rectangular area is completed in 4 tracking cycles. If each beam irradiates two pixels per tracking cycle, the drawing within the rectangular area is completed in 2 tracking cycles.

[0071] In Figures 15 and 16, in the first pass, areas other than the specific region 40 are subjected to normal drawing processing using the entire multi-beam 20. In other words, each pixel is drawn using the entire multi-beam 20. Therefore, hatched pixels are the targets of drawing. When the beam array draws the specific region 40, for example, only the beams of beam group A are used to draw the pixels targeted by each beam. Therefore, only the 2x2 sub-irradiation regions 29 targeted by each beam of beam group A are drawn. The remaining beams are controlled to be beam-off. In Figures 15 and 16, the second pass skips areas other than the specific region 40, which were already drawn in the first pass, and only draws the specific region 40. Here, for example, only the beams of beam group B are used to draw the pixels targeted by each beam. Therefore, only the 2x2 sub-irradiation regions 29 targeted by each beam of beam group B are drawn. The remaining beams are controlled to be off. In Figures 15 and 16, the third pass skips areas other than the specific region 40, as these areas have already been drawn in the first pass, and only the specific region 40 is drawn. Here, for example, only the beams of beam group C are used to draw the pixels targeted by each beam. Therefore, only the 2x2 sub-irradiation regions 29 targeted by each beam of beam group C are drawn. The remaining beams are controlled to be off. In Figures 15 and 16, the fourth pass skips areas other than the specific region 40, as these areas have already been drawn in the first pass, and only the specific region 40 is drawn. Here, for example, only the beams of beam group D are used to draw the pixels targeted by each beam. Therefore, only the 2x2 sub-irradiation regions 29 targeted by each beam of beam group D are drawn. The remaining beams are controlled to be off. In Figure 14, each beam in each beam group overlaps with the overall deflection of the multibeam. Therefore, the plotting of each pass in Figure 15 may be done with different beams between passes as described above, or a single beam group may expose two or more passes.

[0072] As described above, drawing is performed using multiple drawing passes. In this case, the XY stage 105 should be moved at the normal stage speed for each pass. Also, the number of shots for each pass can be the normal number. By performing this segmented drawing, the total current per shot in a specific region 40 can be reduced to 1 / m (1 / 4 in this case) of the normal case. m represents the number of beam groups. Therefore, without using correction means such as correcting the irradiation position or dose amount, the method of drawing can reduce the focus shift of the multi-beam 20, the degradation of beam resolution due to the Coulomb effect (so-called blurring), and / or the positional shift of multiple patterns drawn within the beam array region, which tend to occur in the specific region 40. In addition, although the drawing time increases by increasing the number of passes, the increase in drawing time can be suppressed from the second pass onward by drawing only the specific region 40, which is a very small part of the stripe region 32.

[0073] Alternatively, in segmented drawing, the specific region 40 may be drawn using at least some of the beam groups of multiple beam groups within the same stage pass, which represents the drawing process during a single stage movement in the direction corresponding to the drawing direction of the XY stage 105 on which the sample 101 is placed. In other words, for example, the specific region 40 may be drawn using each beam group while changing the shot timing within the same stage pass, which represents the drawing process during a single stage movement in the direction parallel to the drawing direction of the XY stage 105 on which the sample 101 is placed. In other words, the drawing of the entire stripe region 32 including the specific region 40 is completed in one pass. In such a case, when drawing regions other than the specific region 40, the drawing is performed with the stage speed at the normal stage speed. In contrast, when drawing the specific region 40, the drawing is performed with the stage speed reduced to 1 / m of the normal stage speed. Also, the number of shots for the specific region 40 is m times the number of shots for the rectangular region 35 other than the specific region 40, where m is the number of beam groups. In the example above, the number of shots per rectangular area 35, excluding the specific area 40, should be set to 4. In the specific area 40, the number of shots should be set to 16 (= 4 × 4). Specifically, it works as follows:

[0074] When drawing areas other than the specific region 40, the stage speed is set to the normal stage speed, and the normal drawing process is performed using the entire multi-beam 20. Then, when the beam array begins to pass through the specific region 40, for example, the stage speed is reduced to 1 / m of the normal stage speed. For the specific region 40, while the stage speed is decelerating, the pixels targeted by each beam are drawn using only the beams of beam group A, similar to the first pass in Figures 15 and 16. Therefore, in four beam shots, only the 2x2 sub-irradiation regions targeted by each beam of beam group A are drawn. Next, as shown in the second of the first pass in Figures 15 and 16, for a specific region 40, for example, only the beams of beam group B are used to draw the pixels targeted by each beam. Thus, with four beam shots, only the 2x2 sub-irradiation regions targeted by each beam of beam group B are drawn. Next, as shown in the third step of the first pass in Figures 15 and 16, for a specific region 40, for example, only the beams of beam group C are used to draw the pixels targeted by each beam. Thus, with four beam shots, only the 2x2 sub-irradiation regions targeted by each beam of beam group C are drawn. Next, as shown in Figures 15 and 16, the fourth step of the first pass, for a specific region 40, the pixels targeted by each beam are drawn using, for example, only the beams of beam group D. Thus, with four beam shots, only the 2x2 sub-irradiation regions targeted by each beam of beam group D are drawn. Alternatively, the drawing of a specific region may be performed using some of the beam groups out of m beam groups. For example, the second exposure of the first pass in Figure 15 may be performed by each beam of Group A positioned at the exposure position of each beam of Group B by deflection, and the fourth exposure of the first pass in Figure 15 may be performed by each beam of Group C positioned at the exposure position of each beam of Group D by deflection. Alternatively, all exposures from the first to the fourth of the first pass in Figure 15 may be performed by each beam of Group A. Then, once the beam array has completed passing through a specific region 40, for example, the stage speed is returned to the normal stage speed. For regions other than the specific region 40, the normal drawing process is performed using the entire multi-beam 20 with the stage speed at the normal stage speed. If the specific region 40 needs to be drawn again, the same operation as described above is performed.

[0075] Thus, when drawing a specific region 40, the irradiation timing of each beam group is shifted and the drawing is performed over a period of m times (in this case, 4 times) the time required for other regions. Therefore, when drawing a specific region 40, m times the number of shots required for other regions are performed. This segmented drawing method allows the total current per shot in the specific region 40 to be reduced to 1 / m (in this case, 1 / 4) of the normal amount. Therefore, without using correction means such as correcting the irradiation position or dose amount, this drawing method can reduce the focus shift of the multi-beam 20, the degradation of beam resolution due to the Coulomb effect (so-called blurring), and / or the positional shift of multiple patterns drawn within the beam array region, which tend to occur in the specific region 40. Furthermore, in this drawing method, the stage speed is reduced when drawing the specific region 40, so the beam array does not pass over the specific region 40, and the beams of each beam group can continuously irradiate the specific region 40.

[0076] In the example described above, a different beam was used in each pass for drawing the specific region 40, but this is not the only case. For example, all pixels in the irradiation region 34 may be drawn using the 4x4 beam group that constitutes beam group A shown in the example in Figure 13. In this case, the sub-irradiation region 29 of each beam will be a 2x2 pixel group in areas other than the specific region 40, but for the specific region 40, the sub-irradiation region 29 of each beam will be a 4x4 pixel group. Therefore, in segmented drawing performed with multiple passes, the specific region 40 is also irradiated with beams four times in each pass, just like the areas other than the specific region 40. Thus, the specific region 40 is irradiated with beams a total of 16 times in four passes. In this way, the specific region 40 is drawn by reducing the number of beams and increasing the number of shots compared to areas other than the specific region 40. The increased number of shots may use the same beam group or a different beam group. When using the same beam group, instead of setting up the beam groups so that each beam in one group overlaps with each beam in another beam group due to deflection, as shown in Figures 13 and 14, one could, for example, divide the 4x4 beams into a 2x2 beam group in the center and the other beam groups, and use only the former group to perform the drawing with four times the number of shots.

[0077] As a determination step (S140), the drawing control unit 72 determines whether the drawing of all stripe areas 32 has been completed. If the drawing of all stripe areas 32 has been completed, the drawing process is terminated. If the drawing of all stripe areas 32 has not been completed, the process returns to the rasterization process (S102) and repeats each step, sequentially changing the stripe areas 32 until the drawing of all stripe areas 32 has been completed.

[0078] As described above, according to Embodiment 1, the deterioration of drawing accuracy caused by fluctuations in beam current can be reduced by methods other than correction.

[0079] Embodiment 2. Embodiment 1 describes a configuration in which the determination and identification of a specific region 40 are performed after the shot data has been generated, but it is not limited to this. Embodiment 2 describes a configuration in which the determination and identification of a specific region 40 are performed before the shot data has been generated. The following details may be the same as in Embodiment 1, except for the points that are specifically described.

[0080] Figure 17 is a conceptual diagram showing an example of the configuration of the drawing device in Embodiment 2. Figure 17 is the same as Figure 1, except that a region storage unit 61, a parameter calculation unit 62, and a determination unit 64 have been added to the control computer 110.

[0081] Each of the "~units," such as the Rice Rise Processing Unit 50, Shot Data Generation Unit 52, Parameter Calculation Unit 54, Determination Unit 56, Specific Area Identification Unit 58, Beam Group Setting Unit 60, Area Storage Unit 61, Parameter Calculation Unit 62, Determination Unit 64, Drawing Control Unit 72, and Transfer Processing Unit 74, has a processing circuit. Such processing circuits include, for example, electrical circuits, computers, processors, circuit boards, quantum circuits, or semiconductor devices. Each of the "~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 Rice Rise Processing Unit 50, Shot Data Generation Unit 52, Parameter Calculation Unit 54, Determination Unit 56, Specific Area Identification Unit 58, Beam Group Setting Unit 60, Area Storage Unit 61, Parameter Calculation Unit 62, Determination Unit 64, Drawing Control Unit 72, and Transfer Processing Unit 74, as well as information being calculated, is stored in the memory 112 each time.

[0082] Figure 18 is a flowchart showing an example of the drawing method in Embodiment 2. In Figure 18, the drawing method in Embodiment 2 performs a series of steps: a determination parameter 1 calculation step (S90), a determination step (S92), a specific area identification step (S94), a rasterization process (S102), a shot data generation step (S104), a determination parameter 2 calculation step (S112), a determination step (S122), a beam group setting step (S126), a normal drawing step (S130), a segmented drawing step (S132), and a determination step (S140).

[0083] As the determination parameter 1 calculation step (S90), the parameter calculation unit 54 calculates parameters to be used for determining a specific region 40 using the drawing data. At least one of the following is used as a parameter: the ratio S of patterns in which the beam pitch and pattern pitch are in an integer multiple relationship including matching, the area density ρ of the pattern, and the rate of variation of the area density of the pattern. Here, since the drawing data has not yet been rasterized, there is no rasterized data or shot data. Therefore, the parameters are calculated from the drawing data. The rest is the same as the determination parameter calculation step (S110) in Figure 11. Note that, as a preprocessing step for the drawing process, parameters are calculated for the entire chip area (drawing area 30) in order to search for a specific region 40.

[0084] As a determination step (S92), the determination unit 56 determines whether the calculated parameter is equal to or greater than a threshold. The content of the determination step (S92) is the same as the determination step (S120) in Figure 11. In other words, the determination unit 56 determines, for each rectangular region 35 of the same size as the beam array region in which the multibeams 20 are arranged, whether the ratio S of the array pitch patterns such that the beam pitch and pattern pitch of the multibeams 20 are in an integer multiple relationship including matching is greater than or equal to a threshold Th1 (pattern ratio threshold) for each drawing region (in this case, for example, the stripe region 32) of the sample 101. Furthermore, the determination unit 56 determines whether the area density ρ is equal to or greater than the threshold Th2 (area density threshold) for each rectangular region 35 of the same size as the beam array region in which the multi-beams 20 are arranged, for each drawing region (in this case, for example, the stripe region 32) of the sample 101. Furthermore, the determination unit 56 determines, for each rectangular region 35 of the same size as the beam array region in which the multibeams 20 are arranged, whether the rate of variation Δρ of the area density of the rectangular region 35 relative to the average value of the area density is greater than or equal to the threshold Th3 (rate of variation threshold) with respect to the drawing area of ​​the sample 101 (in this case, for example, the stripe region 32).

[0085] If the determination finds that there is at least one rectangular region 35 whose parameters are equal to or greater than the threshold, the process proceeds to the specific region identification step (S94). If the determination finds that there are no rectangular regions 35 whose parameters are equal to or greater than the threshold, the specific region identification step (S94) is skipped and the process proceeds to the rasterization step (S102).

[0086] As a specific area identification step (S94), the specific area identification unit 58 identifies a specific area 40 from within the drawing area 30. The content of the specific area identification step (S94) is the same as the specific area identification step (S124) in Figure 11. Here, the existence or non-existence of a specific area 40, and if it exists, its position and area, are identified for the entire chip area (drawing area 30). Furthermore, the user may pre-specify a specific area range, and regardless of the result of the determination step (S92), an area within the drawing area 30 that is included in the pre-specified range may be further set as a specific area. The area storage unit 61 stores the specific areas identified in the specific area identification step (S94) and the specific areas entered by the user as a range.

[0087] The information of the identified specific region is added to the drawing data as flag information. This allows the specific region 40 to be defined in the drawing data before the drawing process starts. After this preprocessing is completed, the drawing process begins. The specific operation is described below.

[0088] The contents of the rasterization process (S102) and the shot data generation process (S104) are the same as in Embodiment 1.

[0089] As part of the determination parameter 2 calculation process (S112), the parameter calculation unit 62 calculates the number of ON beams for each shot from the start to the completion of passing through the identified specific region 40 of the beam array, and calculates the variation in the number of ON beams (e.g., 3σ).

[0090] As a determination step (S122), the determination unit 64 determines whether the variation in the number of ON beams is greater than or equal to the threshold Th4. If the variation in the number of ON beams is greater than or equal to the threshold Th4, the rectangular region 35 can be considered a true specific region 40. If the variation in the number of ON beams is greater than or equal to the threshold Th4, the process proceeds to the beam group setting step (S126). If the variation in the number of ON beams is not greater than or equal to the threshold Th4, the specific region 40 is considered to have not existed as a pseudo-specific region, and the process proceeds to the normal drawing step (S130).

[0091] The contents of each step, the beam group setting step (S126), the normal drawing step (S130), the segmented drawing step (S132), and the determination step (S140), are the same as in Embodiment 1.

[0092] As described above, according to Embodiment 2, flags such as the position of a specific region 40 can be defined in the drawing data before the drawing process starts. The determination step (S122) is computationally intensive because it calculates the number of ON beams for each shot of a multibeam using a large number of multibeams. Therefore, the determination step (S122) based on the number of ON beams may be performed only for the region specified in the specific region specification step (S94). In this case, the computational amount for calculating the number of ON beams in the determination step (S122) can be greatly reduced. In addition, by specifying in advance that regions requiring particularly high drawing accuracy and pattern resolution are included in the position range of the specific region, the number of beams can be reduced in such regions to improve drawing accuracy and pattern resolution.

[0093] Figure 19 shows an example of a specific region, beam array region, and stripe region in a modified example of Embodiment 2. When only the beam group in the center of the beam array is used to draw the specific region 40, the width of the stripe region 32 covering the specific region 40 may be changed. For example, as shown in Figure 19, the stripe region covering the specific region 40 is divided into two stripe regions with half the width. This division can be performed based on the result of the specific region identification step (S94) performed as a pre-processing step for drawing. The divided stripe regions are drawn using the beam group in the center of the beam array, selected so that the number of vertical (y-direction) beam arrays is halved. The divided stripe regions are drawn by performing the rasterization step (S102) and subsequent steps in the same way as the other undivided stripes.

[0094] Therefore, in the modified embodiment of the second embodiment, the area containing the specific region 40 is narrowed by dividing the drawing region 30 in a single stage pass in the y direction linearly independent of the movement direction of the XY stage 105, and by narrowing the width of the stripe region and the beam array width.

[0095] Furthermore, the processing functions described in each of the embodiments described above may be made to be executed by a computer. The program for causing the computer to execute such processing functions may be stored, for example, in a tangible, non-temporary, readable recording medium such as a magnetic disk drive. Furthermore, while the example above showed the case with 4 beam groups, this is not the only case. Any number of beam groups, 2 or more, is acceptable.

[0096] 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, while 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. The parameters used in the judgment parameter calculation step and the judgment step may be other than those described above. For example, the percentage of patterns with thin line widths that are susceptible to degradation due to the Coulomb effect, such as 20 nanometers or less, may be used as a parameter.

[0097] 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]

[0098] 20 Multibeam 22 holes 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 40 areas 41 Control circuits 50 Rice Rise Processing Unit 52 Shot data generation unit 54 Parameter Calculation Unit 56 Judgment section 58 Specific area identification part 60 Beam group setting section 61 Area storage section 62 Parameter Calculation Unit 64 Judgment section 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 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 process involves setting up multiple beam groups by array-dividing a multi-charged particle beam to irradiate a specific area within the patterning region of the sample, The process of drawing a pattern in the area of ​​the drawing region of the sample other than the specific area while simultaneously irradiating it with the multi-charged particle beam, The process involves drawing a pattern on the specific region of the sample using the beams of each of the plurality of beam groups, while staggering the irradiation timing for each beam group. A multi-charged particle beam lithography method characterized by comprising the following features.

2. The multi-charged particle beam writing method according to claim 1, characterized in that the specific region is drawn using each beam group, while changing the stage path which indicates the drawing process during one stage movement in a direction corresponding to the drawing direction of the stage on which the sample is placed, for each beam group.

3. The multi-charged particle beam writing method according to claim 1, characterized in that the specific region is drawn using at least some of the beam groups of the plurality of beam groups during the same stage pass, which represents a drawing process during a single stage movement in a direction corresponding to the drawing direction of the stage on which the sample is placed.

4. The multi-charged particle beam lithography method according to any one of claims 1 to 3, further comprising the step of identifying a specific region from the aforementioned lithography region.

5. The drawing area of ​​the sample includes a step of determining whether the area density is equal to or greater than an area density threshold for each predetermined rectangular region, The multi-charged particle beam writing method according to claim 4, characterized in that a rectangular region whose area density is equal to or greater than an area density threshold is identified as the specific region.

6. The drawing area of ​​the sample includes a step of determining whether the rate of change of the area density of a predetermined rectangular region relative to the average area density is greater than or equal to a rate of change threshold, for each predetermined rectangular region. The multi-charged particle beam writing method according to claim 4, characterized in that a rectangular region in which the rate of fluctuation of the area density is greater than or equal to a rate of fluctuation threshold is identified as the specific region.

7. The process includes determining whether, for each predetermined rectangular region of the drawing area of ​​the sample, the proportion of the array pitch patterns such that the beam pitch and pattern pitch of the multi-charged particle beam are in an integer multiple or integer fraction relationship including coincidence is greater than or equal to a pattern ratio threshold. The multi-charged particle beam writing method according to claim 4, characterized in that a rectangular region in which the proportion of array pitch patterns having an integer multiple relationship is greater than or equal to a pattern proportion threshold is identified as the specific region.

8. A setting unit that divides a multi-charged particle beam to set up multiple beam groups, each consisting of at least one beam, which irradiate a specific area within the patterning region of the sample. A drawing mechanism that uses all or part of the multi-charged particle beam to draw a pattern on the sample, Equipped with, The aforementioned drawing mechanism is While simultaneously irradiating the sample with the multi-charged particle beam, a pattern is drawn in the area of ​​the drawing region of the sample other than the specific area. A pattern is drawn on the specific region of the sample using at least one beam from each of the plurality of beam groups, while staggering the irradiation timing for each beam group. A multi-charged particle beam lithography apparatus characterized by the following features.

9. A step of drawing a pattern in a region of the sample other than a specific region, using the number of multi-charged particle beams used for drawing as the reference beam number, A step of drawing a pattern in the specified region using a multi-charged particle beam in which the number of multi-charged particle beams used for drawing is reduced from the number of reference beams and the number of shots is increased from the number of reference shots, A multi-charged particle beam lithography method characterized by comprising the following features.

10. A step of drawing the pattern in the region other than the specified region using a multi-charged particle beam with a reference number of irradiations, The process of drawing a pattern in the specified region using a multi-charged particle beam in which the number of shots is increased compared to the reference number of shots, The multi-charged particle beam lithography method according to claim 9, characterized by comprising the above.

11. The multi-charged particle beam writing method according to claim 9 or 10, characterized in that the region including the specified region is divided into stripe widths and beam array widths in a single stage pass in a linearly independent direction of the stage movement direction.

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