Multi charged particle beam writing method, multi charged particle beam writing apparatus, and storage medium

Abstract

PURPOSE: To provide a drawing method capable of drawing a pattern of accuracy obtained by a low-accuracy drawing device without replacing hardware by a high-accuracy drawing device.CONSTITUTION: According to another aspect of the present invention, there is provided a multi-charged particle beam writing method including a step of setting, in a writing region of a target object, a plurality of writing grids in which relative positions of at least some grids are shifted from a plurality of ideal grids arranged in a lattice shape at an equal pitch, and a writing step of writing a pattern on the target object by irradiating the plurality of writing grids in which relative positions of at least some grids are shifted with multiple beams.SELECTED DRAWING: Figure 17

Description

[Technical Field]

[0001] The present invention relates to a multi-charged particle beam lithography method, a multi-charged particle beam lithography system, and a program, and relates to, for example, a technique for reproducing old-generation pattern lithography in a multi-beam lithography system for cutting-edge processes. [Background technology]

[0002] Lithography technology, which is responsible for the advancement of miniaturization of semiconductor devices, is the only extremely important process in semiconductor manufacturing that generates patterns. In recent years, with the increasing integration density of LSIs, the circuit line width required for semiconductor devices has been getting finer year by year. Here, electron beam (EB) lithography technology has inherently excellent resolution, and lithography is carried out using an electron beam to draw on wafers, etc.

[0003] For example, there is a lithography system that uses multiple beams. Compared to lithography using a single electron beam, using multiple beams allows for the irradiation of many beams at once, thereby significantly improving throughput. In such a lithography system, for example, an electron beam emitted from an electron gun is passed through a mask with multiple holes to form multiple beams, each of which is blanked, and the unblocked beams are reduced in size by an optical system, deflected by a deflector, and irradiated onto the desired position on the sample.

[0004] Here, in multi-beam lithography, for example, a high-precision lithography system used in cutting-edge processes may be required to write a pattern with the accuracy achieved by an older-generation, lower-precision lithography system. Examples include when creating a product identical to a previously produced product, or when the performance required for the final semiconductor device is sufficient for the older generation. For masks, for example, measures have been taken to improve the accuracy of the pattern shape formed on the mask, such as adding auxiliary patterns to the original pattern or resizing the pattern itself. These corrections are called Mask Process Corrections (MPCs), and some of the corrections are performed taking into account the beam resolution of the lithography system. However, with the improvement in lithography accuracy and beam resolution of high-precision lithography systems, when a pattern is written using lithography data used for an older-generation lithography system, the resulting pattern shape may not be the same as when written with the older-generation lithography system. On the other hand, in mask manufacturing, it is desirable for a high-precision lithography system to produce lithography results equivalent to those of a lower-precision lithography system.

[0005] One possible method for achieving this is to replace part of the hardware of a high-precision lithography device with that of a low-precision lithography device, but this poses a problem in that it cannot fully address the need for multiple low-precision specifications. Therefore, it is desirable to use the hardware of a high-precision lithography device to draw patterns with the precision obtained by a low-precision lithography device.

[0006] Here, although it is not to adjust the drawing accuracy to the specifications of the previous generation, a technology has been disclosed in which, in multi-beam drawing, the positions of the holes in the aperture array that form the multi-beams are shifted from regular positions to adjust the distortion of the multi-beams that occurs on the sample surface by the projection optical equipment (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-041055 Summary of the Invention [Problem to be solved by the invention]

[0008] One aspect of the present invention provides a drawing method and a drawing device that can draw a pattern with the accuracy that can be obtained with a low-accuracy drawing device, using a high-accuracy drawing device, without replacing hardware. [Means for solving the problem]

[0009] A multi-charged particle beam writing method according to one aspect of the present invention includes: a step of setting a plurality of drawing grids in a drawing region of the sample, the drawing grids being obtained by shifting the relative positions of at least some of the grids from a plurality of ideal grids arranged at equal pitches in a lattice pattern; a drawing step of drawing a pattern on a sample by using a multibeam to irradiate a plurality of drawing grids, at least some of which are shifted in relative position; The present invention is characterized by the following.

[0010] Preferably, the method further comprises a step of deflecting the multi-beams for each shot based on the amount of misalignment of the grid.

[0011] Preferably, the grid positions of the plurality of drawing grids are shifted at a predetermined pitch from the plurality of ideal grids.

[0012] The method further comprises a step of rasterizing pattern data to be drawn using a plurality of ideal grids, It is preferable that a plurality of drawing grids, the positions of which are shifted, are irradiated with a beam having an irradiation amount for each ideal grid based on data rasterized with a plurality of ideal grids.

[0013] Furthermore, it is preferable that the multiple drawing grids are set so that the sum of vectors representing the positional deviation amount of the drawing grid group within each of the multiple small areas into which an area on the sample surface surrounded by a rectangle the size of the beam pitch of the multi-beam is divided is constant.

[0014] Alternatively / and, it is preferable that multiple drawing grids are set so that the sum of each column and the sum of each row of vectors representing the positional deviation of the drawing grid group within an area on the sample surface surrounded by a rectangle the size of the beam pitch of the multi-beam are constant.

[0015] A multi-charged particle beam writing apparatus according to one aspect of the present invention comprises: a drawing grid setting unit that sets a plurality of drawing grids in a drawing area of ​​the sample, the plurality of grids being obtained by shifting the relative positions of at least some of the grids from a plurality of ideal grids arranged at equal pitches in a lattice pattern; a drawing mechanism that draws a pattern on a sample by irradiating a plurality of drawing grids, at least some of which are shifted in relative position, using a multi-beam; The present invention is characterized by the following.

[0016] A program according to one aspect of the present invention comprises: a process of setting a plurality of drawing grids in a drawing region of the sample, the drawing grids being obtained by shifting the relative positions of at least some of the grids from a plurality of ideal grids arranged at equal pitches in a lattice pattern; a process of storing the set plurality of drawing grids in a storage device; a process of reading out a plurality of drawing grids from the storage device, and causing a drawing mechanism to draw a pattern on a sample using a multibeam by irradiating a plurality of drawing grids, at least some of which are shifted in relative position; to be executed by the computer. [Effects of the Invention]

[0017] According to one aspect of the present invention, a high-precision drawing device can draw a pattern with the same precision as that obtained by a low-precision drawing device without replacing hardware. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a conceptual diagram showing a configuration of a drawing device according to a first embodiment. [Figure 2]FIG. 2 is a conceptual diagram showing the configuration of a shaping aperture array substrate according to the first embodiment. [Figure 3] 2 is a cross-sectional view showing the configuration of a blanking aperture array mechanism in the first embodiment. FIG. [Figure 4] FIG. 2 is a conceptual diagram for explaining an example of a drawing operation in the first embodiment. [Figure 5] 3 is a diagram showing an example of a multi-beam irradiation area and a pixel to be written in the first embodiment. FIG. [Figure 6] 10A and 10B are diagrams showing an example of the amount of positional deviation and the pattern edges formed when the drawing grid is shifted to have an uneven pitch in the first embodiment. [Figure 7] FIG. 10 is a diagram showing an example of the dose distribution when the drawing grid according to the first embodiment is shifted to have an unequal pitch. [Figure 8] FIG. 10 is a diagram showing an example of an effective dose distribution when the plotting grid according to the first embodiment is shifted to have an uneven pitch. [Figure 9] FIG. 10 is a diagram showing an example of a drawing grid pattern when increasing blur in the first embodiment. [Figure 10] FIG. 2 is a diagram illustrating total blur in the first embodiment. [Figure 11] 5A and 5B are diagrams for explaining dimensional uniformity measurement and edge position roughness measurement in the first embodiment. [Figure 12] FIG. 4 is a diagram showing an example of a writing grid pattern for increasing edge position roughness according to the first embodiment. [Figure 13] FIG. 10 is a diagram showing another example of a writing grid pattern for increasing edge position roughness according to the first embodiment. [Figure 14] FIG. 10 is a diagram showing another example of a writing grid pattern for increasing edge position roughness according to the first embodiment. [Figure 15] FIG. 10 is a diagram showing another example of a writing grid pattern for increasing edge position roughness according to the first embodiment. [Figure 16]FIG. 10 is a diagram showing an example of how to shift the writing grid when increasing the amount of deviation of the average position of the pattern according to the first embodiment. [Figure 17] FIG. 2 is a flowchart showing an example of main steps of the writing method according to the first embodiment. [Figure 18] FIG. 4 is a diagram showing an example of the relationship between latitude and writing grid shift amount according to the first embodiment. [Figure 19] FIG. 2 is a diagram for explaining an example of a multi-beam writing operation according to the first embodiment. [Figure 20] FIG. 2 is a diagram showing an example of a pattern formed by drawing in the first embodiment. [Figure 21] FIG. 2 is a diagram for explaining an example of the shape of a pattern edge in the case of multiple writing according to the first embodiment. [Figure 22] FIG. 10 is a diagram for explaining another example of the shape of a pattern edge when multiple writing is performed in the first embodiment. [Figure 23] FIG. 10 is a diagram showing an example of a writing grid pattern when the dimensional uniformity between patterns is deteriorated in the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] In the following embodiments, a configuration using an electron beam will be described as an example of a charged particle beam, but the charged particle beam is not limited to an electron beam and may be a beam using charged particles such as an ion beam.

[0020] Embodiment 1 FIG. 1 is a conceptual diagram showing the configuration of a lithography apparatus according to the first embodiment. In FIG. 1, the lithography apparatus 100 includes a lithography mechanism 150 and a control circuit 160. The lithography apparatus 100 is an example of a multi-charged particle beam lithography apparatus and also an example of a multi-charged particle beam exposure apparatus. The lithography mechanism 150 includes an electron lens barrel 102 (electron beam column) and a lithography chamber 103. Inside the electron lens barrel 102, 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 are arranged.

[0021] An XY stage 105 is disposed within the patterning chamber 103. A sample 101, such as a mask, which will be the patterned substrate during patterning (exposure) is disposed on the XY stage 105. The sample 101 includes an exposure mask used in manufacturing a semiconductor device, or a semiconductor substrate (silicon wafer) on which a semiconductor device is manufactured. The sample 101 also includes a mask blank coated with resist and on which nothing has yet been patterned. A mirror 210 for measuring the position of the XY stage 105 is also disposed on the XY stage 105.

[0022] The control system circuit 160 includes a control computer 110, a memory 112, a deflection control circuit 130, digital-to-analog conversion (DAC) amplifier units 132 and 134, a lens control circuit 136, a stage control mechanism 138, a stage position measurement device 139, and storage devices 140, 142, and 144 such as magnetic disk drives. The control computer 110, the memory 112, the deflection control circuit 130, the lens control circuit 136, the stage control mechanism 138, the stage position measurement device 139, and the storage devices 140, 142, and 144 are connected to one another via a bus (not shown). The deflection control circuit 130 is connected to the DAC amplifier units 132 and 134 and a 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 configured with four or more electrodes, and each electrode is controlled by a deflection control circuit 130 via a DAC amplifier 134. A group of lenses, including the illumination lens 202, the reduction lens 205, and the objective lens 207, is controlled by a lens control circuit 136.

[0023] The position of the XY stage 105 is controlled by driving motors (not shown) for each axis controlled by a stage control mechanism 138. A stage position measuring device 139 receives light reflected from a mirror 210 and measures the position of the XY stage 105 based on the principle of laser interferometry.

[0024] The control computer 110 includes a rasterization processing unit 54, a dose calculation unit 56, an irradiation time calculation unit 58, a drawing grid selection unit 60, a drawing grid setting unit 62, a drawing grid position deviation calculation unit 64, an offset calculation unit 66, a drawing control unit 72, and a transfer processing unit 74. Each of the "~" units, such as the rasterization processing unit 54, the dose calculation unit 56, the irradiation time calculation unit 58, the drawing grid selection unit 60, the drawing grid setting unit 62, the drawing grid misalignment calculation unit 64, the offset calculation unit 66, the drawing control unit 72, and the transfer processing unit 74, has a processing circuit. Such a processing circuit may include, for example, an electric circuit, a computer, a processor, a circuit board, a quantum circuit, or a semiconductor device. 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 rasterization processing unit 54, the dose calculation unit 56, the irradiation time calculation unit 58, the drawing grid selection unit 60, the drawing grid setting unit 62, the drawing grid misalignment calculation unit 64, the offset calculation unit 66, the drawing control unit 72, and the transfer processing unit 74, as well as information being calculated, is stored in the memory 112 each time.

[0025] The drawing operation of the drawing apparatus 100 is controlled by a 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 a transfer processing unit 74.

[0026] 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 on a plurality of figure patterns that constitute the chip pattern. Specifically, for each figure pattern, for example, a figure code, coordinates, size, etc. are defined.

[0027] The storage device 144 also stores a drawing grid list in which a plurality of drawing grid patterns are defined, each of which has a position of each drawing grid shifted by a preset reference shift amount ΔS.

[0028] 1 shows the configuration necessary for explaining the first embodiment. The drawing device 100 may also include other configurations that are normally required.

[0029] FIG. 2 is a conceptual diagram showing the configuration of a shaping aperture array substrate according to the first embodiment. In FIG. 2, holes (openings) 22 are formed in a matrix with a predetermined arrangement pitch of p columns (x direction) by q columns (y direction) (p, q≧2) on the shaping aperture array substrate 203. The example shown in FIG. 2 shows a case where, for example, 512×512 columns of holes 22 are formed in the x and y directions. The number of holes 22 is not limited to this. For example, 32×32 columns of holes 22 may be formed. Each hole 22 is formed as a rectangle of the same size and shape. Alternatively, each hole 22 may be a circle of the same diameter. A portion of the electron beam 200 passes through each of the plurality of holes 22, thereby forming a multibeam 20. In other words, the shaping aperture array substrate 203 forms and emits the multibeam 20. The shaping aperture array substrate 203 is an example of an emission source of the multibeam 20 or a multibeam forming mechanism.

[0030] FIG. 3 is a cross-sectional view showing the configuration of the blanking aperture array mechanism according to the first embodiment. As shown in FIG. 3, the blanking aperture array mechanism 204 includes a blanking aperture array substrate 31, which is made of a semiconductor substrate such as silicon, and is disposed on a support base 33. In a central membrane region 330 of the blanking aperture array substrate 31, passage holes 25 (openings) for passing through each beam of the multi-beams 20 are formed at positions corresponding to the holes 22 of the shaping aperture array substrate 203 shown in FIG. 2. Pairs of control electrodes 24 and counter electrodes 26 (blankers: blanking deflectors) are disposed at positions facing each other across the corresponding passage holes 25 among the plurality of passage holes 25. Furthermore, a control circuit 41 (logic circuit) is disposed inside the blanking aperture array substrate 31 near each passage hole 25, which applies a deflection voltage to the control electrode 24 for each passage hole 25. The counter electrodes 26 for each beam are connected to ground.

[0031] An amplifier (an example of a switching circuit), not shown, is disposed within the control circuit 41. As an example of the amplifier, a CMOS (Complementary MOS) inverter circuit serving as a switching circuit is disposed. To the input (IN) of the CMOS inverter circuit, either an L (low) potential (e.g., ground potential) that is lower than the threshold voltage or an H (high) potential (e.g., 1.5 V) that is equal to or higher than the threshold voltage is applied as a control signal. In the first embodiment, 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 corresponding beam is deflected by an electric field due to the potential difference with the ground potential of the counter electrode 26, and is controlled so that the beam is turned OFF by being shielded by the limiting aperture substrate 206. On the other hand, when an H potential is applied to the input (IN) of the CMOS inverter circuit (active state), the output (OUT) of the CMOS inverter circuit becomes the ground potential, and there is no potential difference with the ground potential of the opposing electrode 26, so the corresponding beam is not deflected, and the beam is controlled to be ON by passing through the limiting aperture substrate 206. Blanking control is performed by this deflection.

[0032] Next, a specific example of the operation of the drawing mechanism 150 will be described. An electron beam 200 emitted from an electron gun 201 (emission source) is illuminated by an illumination lens 202 almost perpendicularly onto the entire shaping aperture array substrate 203. A plurality of rectangular holes 22 (openings) are formed in the shaping aperture array substrate 203, and the electron beam 200 illuminates an area including all of the holes 22. Portions of the electron beam 200 irradiated onto the positions of the holes 22 pass through the holes 22 of the shaping aperture array substrate 203, thereby forming, for example, a rectangular multibeam (multiple electron beams) 20. The multibeam 20 passes through corresponding blankers of a blanking aperture array mechanism 204. Each blanker performs blanking control on the beams passing through it so that the beams are turned on for a set drawing time (irradiation time).

[0033] The multi-beams 20 that pass through the blanking aperture array mechanism 204 are reduced by the reduction lens 205 and travel toward a central hole formed in the limiting aperture substrate 206. Here, the electron beams deflected by the blankers of the blanking aperture array mechanism 204 are shifted from the central hole of the limiting aperture substrate 206 and are blocked by the limiting aperture substrate 206. On the other hand, the electron beams that are not deflected by the blankers of the blanking aperture array mechanism 204 pass through the central hole of the limiting aperture substrate 206 as shown in FIG. 1. In this way, the limiting aperture substrate 206 blocks each beam that is deflected by the blankers of the blanking aperture array mechanism 204 to be in a beam-off state. Then, each beam of one shot is formed by the beams that pass through the limiting aperture substrate 206 from when the beams are turned on until when they are turned off. The multibeams 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, and the entire multibeams 20 that have passed through the limiting aperture substrate 206 are deflected in the same direction by the main deflector 208 and the sub-deflector 209, and each beam is irradiated onto 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 so that the beam irradiation position follows the movement of the XY stage 105. Ideally, the multibeams 20 that are irradiated at one time are arranged at a pitch obtained by multiplying the arrangement pitch of the plurality of holes 22 in the shaping aperture array substrate 203 by the desired reduction ratio described above.

[0034] FIG. 4 is a conceptual diagram illustrating an example of the writing operation in the first embodiment. As shown in FIG. 4, the writing area 30 (bold line) on the sample 101 is virtually divided into a plurality of rectangular stripe regions 32 with a predetermined width in the y direction. The example in FIG. 4 shows a case where the writing area 30 on the sample 101 is divided into a plurality of stripe regions 32 with a width substantially equal to the size of the designed irradiation area 34 (writing field) that can be irradiated with one irradiation of the multibeam 20, for example. The size in the x direction of the designed irradiation area 34 of the multibeam 20 can be defined by the number of beams in the x direction × the beam pitch in the x direction. The size in the y direction of the rectangular irradiation area 34 can be defined by the number of beams in the y direction × the beam pitch in the y direction.

[0035] First, the XY stage 105 is moved and adjusted so that the irradiation area 34 of the multibeam 20 is positioned at the left end of the first stripe region 32 or further to the left, and then the first stripe region 32 is written. When writing the first stripe region 32, the XY stage 105 is moved, for example, in the -x direction, so that writing progresses relatively in the x direction. The XY stage 105 is moved continuously, for example, at a constant speed. After writing the first stripe region 32 is completed, the stage position is moved in the -y direction by an amount equal to the width of the stripe region 32.

[0036] Next, the irradiation area 34 of the multi-beam 20 is adjusted to be positioned at the left end of the second stripe area 32 or at a position further to the left, and the XY stage 105 is moved, for example, in the -x direction, thereby relatively progressing the drawing in the x direction, thereby drawing the second stripe area 32.

[0037] 4 shows the case where each stripe region 32 is written in the same direction, but this is not limiting. For example, the stripe region 32 to be written next to the stripe region 32 written in the x direction may be written in the -x direction by moving the XY stage 105 in the x direction, for example. By writing while alternating directions in this way, the stage movement time can be shortened, and ultimately the writing time can be shortened. In one shot, multiple shot patterns, up to the same number as the holes 22, are formed at once by the multi-beams formed by passing through each hole 22 in the shaping aperture array substrate 203.

[0038] 4 shows a case where the stage is moved once for the writing process of each stripe region, but this is not limiting. It is also preferable to perform multiple writing (multiple pass writing) by moving the stage multiple times over the same position. In this case, it is preferable to perform multiple writing while shifting the position in the y direction by an amount of shift that is 1 / n of the width of the stripe region. Alternatively, it is also preferable to perform multiple writing (intra-pass multiple writing) by writing the same position multiple times with different beams during one stage movement.

[0039] FIG. 5 shows an example of a multibeam irradiation area and a target pixel for drawing in the first embodiment. In FIG. 5, the stripe area 32 is divided into a plurality of mesh areas, for example, based on the beam size of the multibeam 20. Each mesh area corresponds to a target pixel 36 (beam irradiation unit area, irradiation position). The size of the target pixel 36 is not limited to the beam size and may be any size regardless of the beam size. For example, the size may be 1 / n (n is an integer greater than or equal to 1) of the beam size. The example of FIG. 5 shows a case where the target region for drawing on the sample 101 is divided, for example, in the y direction, into a plurality of stripe areas 32, each having a width substantially equal to the size of the irradiation region 34 (drawing field) that can be irradiated with one irradiation of the multibeam 20. The size of the rectangular irradiation region 34 in the x direction can be defined by the number of beams in the x direction multiplied by the beam pitch in the x direction. The size of the rectangular irradiation region 34 in the y direction can be defined by the number of beams in the y direction multiplied by the beam pitch in the y direction. In the example of Figure 5, for example, a 512 x 512 array of multi-beams is shown as an 8 x 8 array of multi-beams. A plurality of pixels 28 (beam drawing positions) that can be irradiated with one shot of the multi-beams 20 are shown within the irradiation area 34. The pitch between adjacent pixels 28 is the inter-beam pitch of each of the multi-beams. A rectangular area surrounded 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 of Figure 5, each sub-irradiation area 29 is shown as being composed of, for example, 4 x 4 pixels.

[0040] Each pixel 36 is formed around each drawing grid 27. Ideally, each drawing grid 27 corresponds to a different one of a plurality of ideal grids arranged at equal intervals on a plurality of straight lines in a grid pattern. For example, each drawing grid 27 corresponds to a different one of a plurality of ideal grids arranged at the intersections of a plurality of straight lines in a grid pattern arranged at equal intervals.

[0041] As described above, in multi-beam lithography, for example, a current-generation high-precision lithography device used in cutting-edge processes may be required to write a pattern with the same accuracy as that obtained by a previous-generation low-precision lithography device. However, with the improvement in lithography accuracy of a high-precision lithography device, writing a pattern using lithography data used in a previous-generation lithography device may result in a failure to obtain a desired pattern shape. Therefore, it is desirable for a high-precision lithography device to be able to obtain lithography results equivalent to those of a low-precision lithography device.

[0042] Therefore, in the first embodiment, an increase in blur of the dose distribution occurring at the irradiation position of the electron beam on the sample 101, an increase in line edge roughness (LER), and / or an increase in deviation of the average pattern position are intentionally caused, so that a high-precision drawing device can draw a pattern with the same precision as a low-precision drawing device. This will be specifically described below.

[0043] FIG. 6 is a diagram showing an example of the amount of positional deviation and the pattern edges formed when the drawing grid according to the first embodiment is shifted to have an uneven pitch. FIG. 7 is a diagram showing an example of the dose distribution when the drawing grid according to the first embodiment is shifted to have an uneven pitch. FIG. 8 is a diagram showing an example of an effective dose distribution when the plotting grid according to the first embodiment is shifted to have an uneven pitch.

[0044] The example in Figure 6 shows a portion of a drawing area where the beam pitch is four times the beam size and the exposure grid spacing is the same as the beam size. Therefore, a rectangular area 35 with a height and width equal to the beam pitch is composed of 4 × 4 pixels. The four drawing grids arranged in the x direction in the first row of each rectangular area 35 in the y direction are shifted from the ideal grid by a reference shift amount ΔS, starting from the left, in the -y direction, -x direction, +x direction, and +y direction. The four drawing grids arranged in the x direction in the second, third, and fourth rows of each rectangular area 35 in the y direction are also shifted from the ideal grid. The shift direction and amount are set so that the sum of the vectors representing the shift amounts for each column and each row is zero. In this case, the vector representing the shift amount is the same for each beam pitch. By irradiating each drawing grid at a position shifted from the ideal grid position with a beam in this way, the dose distribution shown in Figure 7 is obtained. Furthermore, assuming that the total blur, which is the sum of beam blur and resist blur, is the same size as the beam size, if we convolve the distribution function showing the total blur with the dose distribution in Figure 7, we can see that the effective dose near the pattern edge will no longer be uniform, as shown in Figure 8, and the pattern edge can be made, for example, wavy rather than straight, as shown in Figure 6.

[0045] By utilizing this phenomenon, in the first embodiment, the position of the writing grid is intentionally shifted (offset) from the position of the ideal grid to realize an increase in blur of the dose distribution occurring at the irradiation position of the electron beam on the sample 101, an increase in edge position roughness (LER), or an increase in deviation of the average pattern position. The combination pattern of the amount of shift (offset) of the writing grid from the ideal grid and the direction is changed according to the desired increase in blur, an increase in edge position roughness (LER), or an increase in deviation of the average pattern position. These correspond, in order, to cases where the period of the writing grid deviation distribution is short to long. Depending on the period of the deviation distribution, the two effects may appear mixed.

[0046] Fig. 9 is a diagram showing an example of a drawing grid pattern when increasing blur in embodiment 1. In the example of Fig. 9, the position of each drawing grid 27 is shifted from the position of the ideal grid 17 for each sub-irradiation region 29 in the stripe region 32. The example of Fig. 9 shows a case where each sub-irradiation region 29 is made up of 4 x 4 drawing grids 27 (or pixels).

[0047] 10 is a diagram for explaining total blur in the first embodiment. In addition to the beam blur (beam blur) that indicates the beam spread due to the optical system, the electron beam also generates a development-stage blur (resist blur) that indicates the spread of electrons due to the diffusion of acid in the resist irradiated with the beam. Using the standard deviation σ1 of the beam blur distribution function and the standard deviation σ2 of the resist blur distribution function, the total blur distribution function g(x) can be defined by the following formula (1-1), for example, using a Gaussian distribution function. The standard deviation σ3 of the total blur distribution function can be defined by formula (1-2).

[0048]

number

[0049] The dose distribution d'(x) at the irradiation position of the sample 101 after development can be defined by the following equation (2) using the incident dose d(x).

[0050]

number

[0051] To increase the blur, the shift (position shift) period of the drawing grid 27 is set to be smaller than the σ3 of the total blur. Generally, the σ3 of the total blur is larger than the beam size. For example, when the beam size is 20 nm, σ3 is 20 to 30 nm. In the example of FIG. 9, the drawing grid 27 is shifted at a pitch equal to or smaller than the arrangement pitch of the drawing grid 27. In other words, each drawing grid 27 is shifted. The drawing grid pattern is set so that the sum of vectors representing the local positional deviation from the ideal grid 17 within the sub-irradiation region 29, for example, the positional deviation from the ideal grid 17 of the group of drawing grids 27 within a sub-pitch cell 23, is zero. In the example of FIG. 9, the sub-irradiation region 29 on the surface of the sample 101, surrounded by a rectangle the size of the beam pitch of the multi-beam 20, is divided into a plurality of sub-pitch cells 23. The plurality of drawing grids 27 are set so that the average positional deviation of the group of drawing grids 27 within each sub-pitch cell 23 is zero. 9 shows a case where the sub-irradiation area 29 is composed of 4×4 drawing grids (or pixels), and the sub-pitch cell 23 is composed of 2×2 drawing grids (or pixels). In each sub-pitch cell 23, the positions of the 2×2 drawing grids are shifted from the ideal grid by the same positional deviation amount in the +x, −x, +y, and −y directions. By setting the sum of vectors representing the amount of local positional deviation from the ideal grid 17 within the sub-irradiation region 29 to zero, it is possible to suppress deterioration of critical dimension uniformity (CDU) due to shifts in the drawing grid.

[0052] Furthermore, the direction and amount of misalignment are set so that the sum of vectors representing the amount of misalignment of each column of the group of drawing grids 27 in each sub-irradiation area 29 from the ideal grid 17 is zero, and the sum of vectors representing the amount of misalignment of each row of the group of drawing grids 27 from the ideal grid 17 is zero. This makes it possible to suppress deterioration of edge position roughness (LER). The sum of the vectors representing the amount of positional deviation does not necessarily have to be zero, but the same effect can be obtained as long as it is constant.

[0053] The drawing grid pattern is the same for each sub-irradiation region 29. As a result, for each shot of the multi-beam 20, the drawing grids 27 to be irradiated are shifted in the same direction and by the same amount, and can be shifted by collective deflection of the multi-beam 20.

[0054] Then, by making the pitch of the shift (positional displacement) of the drawing grid 27 smaller than the total blur σ3, it is possible to increase the blur without changing the shape of the pattern edge.

[0055] In the above example, the shift pitch of the drawing grid is set to 1 drawing grid, but this is not limited to this. For example, if the beam size is 20 nm and σ3 is 80 nm, the shift pitch may be set to 2 drawing grids or 3 drawing grids. If the shift (positional shift) pitch of the drawing grid is set smaller than the σ3 of the total blur, the drawing grid shift occurs within the total blur, and the shift amount is buried in the blur, so the blur can be increased without changing the shape of the pattern edge.

[0056] 11 is a diagram for explaining the dimension uniformity measurement and edge position roughness measurement in the first embodiment. In the line critical dimension (LCD) measurement, the average line width dimension of a pattern within an area having a length of, for example, about 1 μm is measured. On the other hand, in the line edge roughness (LER) measurement, the variation in the pattern edge position is measured within an area that is sufficiently smaller than the area used for the CDU measurement.

[0057] Fig. 12 is a diagram showing an example of a drawing grid pattern that increases the edge position roughness in Embodiment 1. In the example of Fig. 12, each sub-irradiation region 29 is configured with a group of 8 x 8 drawing grids 27 (or pixels).

[0058] To increase the edge position roughness (LER), the shift (positional displacement) pitch of the drawing grid 27 is set to be approximately equal to or slightly larger than the total blur σ3. For example, when the drawing grid spacing is 20 nm and σ3 is 20 to 30 nm, in the example of FIG. 12, the drawing grid 27 is shifted by, for example, two drawing grid 27 pitches. Here, multiple drawing grids 27 are set so that the sum of the column vectors and the sum of the row vectors representing the positional displacement of the drawing grids 27 within a sub-irradiation region 29 on the surface of the sample 101, which is surrounded by a rectangle the size of the beam pitch of the multi-beam 20, are zero. In each sub-irradiation region 29, the positions of two drawing grids in each column are shifted from the ideal grid 17 by the same displacement amount in the +x, -x, +y, and -y directions. Similarly, in each row, two drawing grids 27 are shifted in the +x, -x, +y, and -y directions by the same displacement amount from the ideal grid 17. Note that the sum of the vectors representing the displacement amount does not necessarily have to be zero, and a similar effect can be obtained as long as it is constant.

[0059] The drawing grid pattern is the same for each sub-irradiation region 29. As a result, for each shot of the multi-beam 20, the drawing grids 27 to be irradiated are shifted in the same direction and by the same amount, and can be shifted by collective deflection of the multi-beam 20.

[0060] By making the shift (positional displacement) pitch of the drawing grid 27 equal to or slightly larger than the total blur σ3, the shift effect is not canceled out by the total blur, and the pattern edge can be changed from a straight line to a gentle wave. As a result, the LER can be increased. On the other hand, the average value in the CDU measurement area is close to zero, so the shift effect can be prevented from affecting the CDU.

[0061] FIG. 13 is a diagram showing another example of a writing grid pattern for increasing the edge position roughness according to the first embodiment. FIG. 14 is a diagram showing another example of a writing grid pattern for increasing the edge position roughness according to the first embodiment. The example of Figure 13 shows a case where, for example, the first row of drawing grids in the sub-irradiation area 29 shifts by two drawing grids in the -x, +x, +y, -y directions in this order. On the other hand, the example of Figure 14 shows a case where, for example, the first row of drawing grids in the sub-irradiation area 29 shifts by four drawing grids in the -x and -y diagonal directions, followed by the +x and +y diagonal directions in this order. In this way, by changing the shift pitch from two drawing grids to four drawing grids, the period of the gentle curve of the pattern edge can also be doubled. Therefore, it can be seen that the period of the undulating curve of the pattern edge can be controlled by adjusting the shift pitch.

[0062] FIG. 15 illustrates another example of a grid pattern for increasing edge position roughness in the first embodiment. The example in FIG. 15 illustrates a case in which, for example, a first-stage grid group in the sub-irradiation region 29 is shifted by four grids at a time, first in the −x and −y diagonal directions, and then in the +x and +y diagonal directions. In the example in FIG. 15, the shift amounts of the four grids in the −x and −y diagonal directions are gradually decreased, while the shift amounts of the four grids in the +x and +y diagonal directions are gradually increased. While the pattern edge of the four grids with the same shift period shown in FIG. 14 is a sinusoidal curve, the example in FIG. 15 can be a triangular curve. Therefore, the shape of the curve of the pattern edge can be changed by changing the shift amount of the grids within the shift period.

[0063] FIG. 16 shows an example of how to shift the writing grid when increasing the deviation of the average position of the pattern in the first embodiment. To increase the deviation of the average position of the pattern, the pitch of the shift (position shift) of the writing grid 27 is set to be equal to or larger than the beam array size. In the example of FIG. 16, the position of each writing grid 27 is shifted from the position of the ideal grid 17 for each rectangular region 35 of the same size as the beam array. The rectangular region 35 is preferably defined to be the same size as the irradiation region 34. In multi-beam writing, as shown in FIG. 4, the irradiation region 34 gradually advances in the writing direction to write the stripe region 32. At this time, tracking operations are repeated, as described below. If, for example, 10 tracking operations are required to perform shots on all pixels 36 in one rectangular region 35, the writing grid 27 is shifted after every 10 tracking operations. For example, in the 1st to 10th tracking operations, the shift amount of the drawing grid 27 is zero, in the 11th to 20th tracking operations, the shift amount of the drawing grid 27 in the +y direction from the ideal grid 17 is 5 nm, in the 21st to 30th tracking operations, the shift amount of the drawing grid 27 in the -y direction from the ideal grid 17 is 5 nm, in the 31st to 40th tracking operations, the shift amount of the drawing grid 27 from the ideal grid 17 is zero, ... This is repeated. In this way, the pattern position can be slowly shifted in units of, for example, several tens of μm.

[0064] As described above, by changing the shift (positional displacement) pitch of the writing grid 27 according to the purpose, it is possible to increase the blur of the dose distribution occurring at the irradiation position of the electron beam on the sample 101, increase the edge position roughness (LER), or increase the deviation of the average pattern position. Two or three of these may be performed simultaneously. In this case, writing may be performed by applying a shift amount obtained by adding up the shift amounts applied for each purpose.

[0065] The specific operation will be described below.

[0066] Fig. 17 is a flowchart showing an example of main steps of the writing method according to Embodiment 1. In Fig. 17, the writing method according to Embodiment 1 carries out a series of steps including a rasterization process step (S102), a dose calculation step (S104), an irradiation time calculation step (S106), a writing grid selection step (S110), a writing grid setting step (S112), a writing grid position deviation amount calculation step (S120), a grid offset amount calculation step (S122), and a writing (grid shift deflection) step (S130).

[0067] In the rasterization process step (S102), the rasterization processing unit 54 rasterizes the pattern data to be drawn using a plurality of ideal grids 17. In other words, the rasterization processing unit 54 reads out chip pattern data (drawing data) from the storage device 140 and performs the rasterization process. Specifically, the pattern density ρ (pattern area density) is calculated for each pixel 36 of the ideal grid 17.

[0068] In the dose calculation step (S104), the dose calculation unit 56 first calculates a proximity effect-corrected dose Dp(x) for correcting the proximity effect for each proximity mesh region. The unknown proximity effect-corrected dose Dp(x) can be defined by a threshold model for proximity effect correction similar to the conventional method, using a backscattering coefficient η, a dose threshold Dth of a threshold model, a pattern area density ρ″, and a distribution function f(x). The proximity effect-corrected dose Dp(x) is calculated as a relative value normalized with a base dose Dbase set to 1. The size of the proximity mesh region is preferably set to about 1 / 10 of the radius of influence of the proximity effect, for example, about 1 μm.

[0069] Next, the dose calculation unit 56 calculates the incident irradiation dose d(x) (dose) for each pixel 36 of the ideal grid 17 to irradiate that pixel 36. The incident irradiation dose d(x) may be calculated, for example, as the product of the reference irradiation dose Dbase multiplied by the proximity effect-corrected irradiation dose Dp and the pattern area density ρ. The reference irradiation dose Dbase may be defined, for example, as Dth / (1 / 2 + η). As a result, the proximity effect-corrected incident irradiation dose d(x) for each pixel can be obtained based on the layout of multiple graphic patterns defined in the drawing data. Alternatively, the dose calculation unit 56 may preferably define the incident irradiation dose d(x) for each pixel as the incident irradiation dose d(x) normalized by setting the reference irradiation dose Dbase to 1. In this case, the incident irradiation dose d(x) may be calculated, for example, as the product of the proximity effect-corrected irradiation dose Dp multiplied by the pattern area density ρ.

[0070] Next, the dose calculation unit 56 creates a dose map whose elements are the incident irradiation dose d(x) of each pixel 36. In other words, each pixel (position) (x, y) is defined in association with the incident irradiation dose d(x) of that pixel. The created dose map is stored in the storage device 142. The dose calculation unit 56 creates a dose map for the entire drawing region 30 where drawing processing is performed in accordance with the drawing data (chip data).

[0071] When multiple drawing processes are performed, a dose map is created for each of the multiple drawing processes.

[0072] In the irradiation time calculation step (S106), the irradiation time calculation unit 58 uses the incident irradiation amount d(x) (dose amount) to calculate the irradiation time t for each pixel 36. The irradiation time t for each pixel 36 can be calculated by dividing the incident irradiation amount d(x) of the pixel by the current density J. When the incident irradiation amount d(x) defined in the dose map is normalized with the reference irradiation amount Dbase set to 1, the irradiation time t for each pixel 36 can be calculated by multiplying the incident irradiation amount d(x) by the reference irradiation amount Dbase and dividing the result by the current density J.

[0073] Then, the drawing control unit 72 rearranges the obtained irradiation time data for each pixel 36 in shot order and stores it in the storage device 142. The transfer processing unit 74 transfers the irradiation time data to the deflection control circuit 130 in shot order.

[0074] In the drawing grid selection step (S110), the drawing grid selection unit 60 references the drawing grid list from the storage device 144 and selects from a plurality of drawing grid patterns a drawing grid pattern that will achieve the desired effect. To increase the blur, a drawing grid pattern is selected in which the shift (position shift) pitch of the drawing grid 27 is set smaller than the σ3 of the total blur. To increase the LER, a drawing grid pattern is selected in which the shift (position shift) pitch of the drawing grid 27 is set approximately equal to the σ3 of the total blur. To increase the average positional deviation of the pattern, a drawing grid pattern is selected in which the shift (position shift) pitch of the drawing grid 27 is set equal to or larger than the beam array size. The σ3 of the total blur is measured in advance by experiment or simulation.

[0075] In the drawing grid setting step (S112), the drawing grid setting unit 62 sets, in the drawing region of the sample 101, multiple drawing grids 27, which are obtained by shifting the relative positions of at least some of the grids from multiple ideal grids 17 arranged at equal intervals in a grid pattern. For example, the drawing grid setting unit 62 sets, in the stripe region 32 (drawing region) of the sample 101, multiple drawing grids 27, which are obtained by shifting the positions of the grids, for example, by a predetermined pitch in the drawing direction (x direction), from multiple ideal grids 17 arranged at equal intervals on multiple straight lines in a grid pattern. Here, the shift amount (position shift amount) of each drawing grid of the selected drawing grid pattern is changed depending on the blur, LER, and / or the average position shift amount of the pattern obtained with an older-generation drawing device. The shift amount of the selected drawing grid pattern is the reference shift amount ΔS, which can be increased or decreased by multiplying it by a coefficient k to match the performance obtained with the older-generation drawing device. To obtain multiple effects, a drawing grid pattern is created by adding drawing grid patterns corresponding to each effect and its coefficient, and then set this drawing grid pattern.

[0076] Regarding the LER and / or the deviation amount of the average position of the pattern, the amplitude of the curve of the obtained pattern edge can be increased by increasing the shift amount of the drawing grid.

[0077] FIG. 18 is a diagram showing an example of the relationship between latitude and the writing grid shift amount in the first embodiment. In FIG. 18, the vertical axis represents latitude (nm / % dose), and the horizontal axis represents the writing grid shift amount (nm). The latitude indicates the amount of change in pattern line width per unit dose. As shown in FIG. 18, as the writing grid shift amount increases, the latitude also increases. The larger the blur, the more gradual the rise in the dose distribution becomes rather than abrupt, and therefore the amount of change in pattern line width per unit dose increases. In other words, the larger the blur, the greater the latitude. Therefore, as with LER and the amount of deviation of the average position of the pattern, the increase in blur can also be increased by increasing the writing grid shift amount.

[0078] Information about each set drawing grid is stored in the storage device 142.

[0079] In the drawing grid misalignment amount calculation step (S120), the drawing grid misalignment amount calculation unit 64 reads information on a plurality of drawing grids from the storage device 142, and calculates the misalignment amount of each drawing grid 27 in the stripe region 32. The drawing grid misalignment amount calculation unit 64 creates a misalignment map whose elements are the misalignment amounts of each drawing grid, and stores the map in the storage device 142.

[0080] In the grid offset amount calculation step (S122), the offset calculation unit 66 calculates the offset direction and offset amount of the drawing grid 27 for each shot of the multi-beam 20. As described above, the shift direction and shift amount of the drawing grid 27 that have the same positional relationship are set to be the same for each sub-irradiation region 29. Therefore, for each shot, the multi-beam 20 can be deflected collectively in the calculated offset direction and offset amount.

[0081] Here, when the next writing process is performed, in addition to the case where the positional deviation map is used for control, a deflection shift amount map may be created by adding the grid offset amount at the time of the switching to the sub-deflection shift amount of the sub-deflection deflector 209 used for switching the pixel to be irradiated for each shot or the main deflection shift amount of the main deflector 208 for each tracking cycle, and the deflection shift amount map may be used for control.

[0082] In the writing (grid shift deflection) step (S130), under the control of the writing control unit 72, the writing mechanism 150 uses the multibeam 20 to write a pattern on the sample 101 so as to irradiate a plurality of writing grids 27, at least some of which have shifted relative positions. At this time, the writing mechanism 150 irradiates a plurality of writing grids 27, each of which has shifted grid positions, with the multibeam 20, using a beam with an incident irradiation amount d(x) for each ideal grid 17 based on data rasterized using the plurality of ideal grids 17. In addition, the sub-deflector 209 deflects the multibeam 20 for each shot based on the shift amount (positional deviation amount) of the grid. As a result, a position shifted by the grid shift amount from the ideal grid 17 defined for each writing grid 27 is irradiated with the beam for that writing grid.

[0083] FIG. 19 is a diagram illustrating an example of a multi-beam writing operation in the first embodiment. The example of FIG. 19 illustrates a case where writing is performed with four different beams in each sub-irradiation area 29, each of which includes one beam irradiation position of the multi-beams 20 and is surrounded by a beam pitch. The example of FIG. 19 also illustrates a writing operation in which the XY stage 105 continuously moves at a speed of a distance L equivalent to eight beam pitches while writing ¼ of each sub-irradiation area 29 (one corresponding to the number of beams used for irradiation). The example of FIG. 19 illustrates a case where each sub-irradiation area 29 is composed of, for example, 4×4 pixels. In the writing operation illustrated in the example of FIG. 19, for example, while the XY stage 105 moves the distance L equivalent to eight beam pitches, the sub-deflector 209 sequentially shifts the irradiation positions (pixels 36), thereby writing (exposing) four different pixels 36 in the same sub-irradiation area 29. During the writing (exposure) of these four pixels 36, the main deflector 208 deflects the entire multibeam 20 collectively to prevent the relative position of the irradiation area 34 to the sample 101 from shifting due to the movement of the XY stage 105, thereby allowing 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, tracking is reset and the system returns to the previous tracking start position. Note that since writing of the first pixel row from the right in each sub-irradiation area 29 has been completed, after tracking reset, the sub-deflector 209 first deflects the beam to align (shift) the writing position of the beam so that writing of an unwritten pixel row in each sub-irradiation area 29, for example, the second pixel row from the right, is performed. By repeating this operation during writing of the stripe area 32, the position of the irradiation area 34 (34a to 34o) of the multibeam 20 is sequentially moved, as shown in the lower diagram of Figure 4, and writing is performed.

[0084] For example, when the purpose is to increase blur and / or LER, when performing such a drawing operation along a drawing grid pattern, the sub-deflector 209 collectively deflects the multi-beams 20 for each shot by the grid shift amount defined for the drawing grid 27 (pixel 36), thereby shifting the position of the drawing grid 27 from the position of the ideal grid 17. In the example of FIG. 19 , when drawing the pixel 36 in the first row of the first pixel column from the right in each sub-irradiation region 29, the beam irradiation position is shifted by beam deflection by the sub-deflector 209 by the grid shift amount defined for the drawing grid 27 of that pixel. After the shot cycle T is completed, when drawing the pixel 36 in the next second row, the beam irradiation position is shifted by beam deflection by the sub-deflector 209 by the grid shift amount defined for the drawing grid 27 of that pixel. Then, after the shot cycle T is completed, when drawing the pixel 36 in the next third row, the irradiation position of the beam is shifted by beam deflection using the sub-deflector 209 by the grid shift amount defined in the drawing grid 27 of that pixel. Then, after the shot cycle T is completed, when drawing the pixel 36 in the next fourth row, the irradiation position of the beam is shifted by beam deflection using the sub-deflector 209 by the grid shift amount defined in the drawing grid 27 of that pixel. Then, after the shot cycle T is completed, when drawing the pixel 36 in the first row of the second pixel column from the right in the sub-irradiation region 29 shifted by 8 beam pitches by a tracking reset, the irradiation position of the beam is shifted by beam deflection using the sub-deflector 209 by the grid shift amount defined in the drawing grid 27 of that pixel. This process is repeated thereafter in the same manner.

[0085] For example, if the objective is to increase the amount of deviation of the average position of the pattern, when performing such a drawing operation along the drawing grid pattern, the position of the drawing grid 27 during the tracking cycle is shifted from the position of the ideal grid 17 by, for example, collectively deflecting the multi-beams 20 by the main deflector 208 by a grid shift amount corresponding to the number of tracking operations.

[0086] 20 is a diagram showing an example of a pattern formed by writing in Embodiment 1. By writing while shifting (offsetting) the position of the writing grid in accordance with the performance of a desired older-generation writing device, as shown in FIG. 20, a figure pattern (solid line) in which the edge position of the designed figure pattern (dotted line) is shifted can be formed by writing.

[0087] FIG. 21 is a diagram illustrating an example of the shape of a pattern edge when multiple writing is performed in the first embodiment. For example, even when a writing grid pattern for LER is used, by performing grid shifts of the same grid shift amount in opposite directions on one side of the double multiple writing, it is possible to increase blur while suppressing an increase in LER. In the example of FIG. 21, when multiple writing is performed twice while performing grid shifts of the same grid shift amount in the +x direction and the −x direction, it is possible to increase blur while suppressing an increase in LER at the pattern edge in the x direction (edge ​​extending in the y direction). In the example of FIG. 21, since multiple writing is not performed in opposite directions in the y direction, the pattern edge is formed as a wavy line, which causes an increase in LER.

[0088] FIG. 22 is a diagram illustrating another example of the shape of a pattern edge when multiple writing is performed according to the first embodiment. For example, even when using a writing grid pattern for LER, by performing grid shifts of the same grid shift amount in opposite directions in the x direction between one and the other of two of the four multiple writings and performing grid shifts of the same grid shift amount in opposite directions in the y direction between one and the other of the remaining two multiple writings, it is possible to increase blur while suppressing an increase in LER. In the example of FIG. 22, when multiple writing is performed four times while performing grid shifts of the same grid shift amount in the +x direction, the −x direction, the +y direction, and the −y direction, it is possible to increase blur while suppressing an increase in LER at the pattern edges in the x direction (edges extending in the y direction) and the pattern edges in the y direction (edges extending in the x direction). In the example of FIG. 22, multiple writing is also performed in opposite directions in the y direction, so the pattern edges remain straight, and blur can be increased while suppressing an increase in LER.

[0089] Here, in addition to the aforementioned increases in blur, LER, and deviation in the average pattern position, the degradation of dimensional uniformity (CDU) among multiple patterns can be cited as issues that need to be addressed to match the performance of older generation drawing devices.

[0090] Fig. 23 is a diagram showing an example of a writing grid pattern in the case where the dimensional uniformity between patterns is deteriorated in Embodiment 1. In the example of Fig. 23, a case where each sub-irradiation region 29 is composed of an 8 x 8 group of writing grids 27 (or pixels) is shown.

[0091] To degrade the CDU, the misalignment amounts of the drawing grids 27 within a sub-irradiation area 29 on the surface of the sample 101, which is surrounded by a rectangle the size of the beam pitch of the multi-beam 20, are set so that the misalignment amounts in the x direction for multiple columns aligned in the y direction are the same but different in the y direction, and the sums of the vectors representing the misalignment amounts for each column are different. Similarly, the misalignment amounts of the drawing grids 27 within multiple rows aligned in the x direction are set so that the misalignment amounts in the y direction for each row are the same but different in the x direction, and the sums of the vectors representing the misalignment amounts for each row are different. This allows the average position of the pattern edge to be shifted by a predetermined amount in the desired direction. In the example of Figure 23, the average position of the pattern edge can be shifted by, for example, 1 nm in the +y direction. This allows the line width of some of the patterns to be changed. As a result, the CDU can be degraded.

[0092] As described above, according to the first embodiment, a high-precision drawing device can draw a pattern with the accuracy obtained by a low-precision drawing device without replacing hardware. Furthermore, by increasing the total blur by a desired value, the performance of the current-generation drawing device 100, which has high performance, can be matched to the performance of an older-generation drawing device. Furthermore, the drawing accuracy can be limited by a method other than increasing the total blur.

[0093] The above describes the embodiments with reference to specific examples. However, the present invention is not limited to these specific examples. In the above embodiments, all grids are shifted from the ideal grid, but it is not necessary to shift all grids from the ideal grid. For example, by shifting by ¼ or more of the total, the desired effect can be similarly obtained. The processing functions described in the above embodiments may be executed by a computer, and a program for causing a computer to execute such processing functions may be stored in a non-transitory, tangible readable recording medium such as a magnetic disk device.

[0094] Although the description of the device configuration, control method, and other parts not directly necessary for the explanation of the present invention have been omitted, the required device configuration and control method can be appropriately selected and used. For example, the description of the control unit configuration that controls the drawing device 100 has been omitted, but it goes without saying that the required control unit configuration can be appropriately selected and used.

[0095] In addition, all other multi-charged particle beam writing methods, multi-charged particle beam writing apparatuses, and programs that include the elements of the present invention and that can be appropriately modified by those skilled in the art are included within the scope of the present invention. [Explanation of symbols]

[0096] 17 Ideal Grid 20 Multibeam 22 holes 23 Sub-pitch cells 24 control electrode 25 Passing hole 26 Counter electrode 27 Drawing Grid 36 pixels 29 Sub-irradiation area 32 stripe area 34 Irradiation area 35 rectangular area 41 Control circuit 54 Rasterization processing section 56 Dose calculation unit 58 Irradiation time calculation unit 60 Drawing grid selection section 62 Drawing grid setting section 64 Drawing grid position deviation calculation unit 66 Offset calculation unit 72 Drawing control unit 74 Transfer Processing Unit 100 drawing device 101 Sample 102 Electron Telescope 103 Drawing room 105 XY stage 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 140,142,144 Storage device 150 Drawing mechanism 160 Control Circuits 200 electron beam 201 Electron Gun 202 Lighting lens 203 Shaped 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 Region

Claims

1. a step of setting a plurality of drawing grids in a drawing region of the sample, the drawing grids being obtained by shifting the relative positions of at least some of the grids from a plurality of ideal grids arranged at equal pitches in a lattice pattern; a drawing step of drawing a pattern on the sample by using a multibeam to irradiate the plurality of drawing grids, at least some of which are shifted in relative position; A multi-charged particle beam writing method comprising:

2. 2. The multi-charged particle beam writing method according to claim 1, further comprising the step of deflecting the multi-beams for each shot based on the amount of misalignment of the grid.

3. 2. The multi-charged particle beam writing method according to claim 1, wherein the grid positions of the plurality of writing grids are shifted from the plurality of ideal grids at a predetermined pitch.

4. further comprising a step of rasterizing pattern data to be drawn using the plurality of ideal grids; 3. A multi-charged particle beam writing method according to claim 1, wherein the plurality of writing grids, the positions of which are shifted, are irradiated with a beam having an irradiation amount for each ideal grid based on data rasterized with the plurality of ideal grids.

5. 3. A multi-charged particle beam drawing method as claimed in claim 1, wherein the plurality of drawing grids are set so that the sum of vectors representing the positional deviation of a group of drawing grids within each of a plurality of small areas into which an area on a sample surface surrounded by a rectangle the size of the beam pitch of the multi-beam is divided is constant.

6. 3. A multi-charged particle beam drawing method according to claim 1, wherein the plurality of drawing grids are set so that the sum of each column and the sum of each row of vectors representing the positional deviation of a group of drawing grids within an area on the sample surface surrounded by a rectangle the size of the beam pitch of the multi-beams are constant.

7. a drawing grid setting unit that sets a plurality of drawing grids in a drawing area of ​​the sample, the plurality of grids being obtained by shifting the relative positions of at least some of the grids from a plurality of ideal grids arranged at equal pitches in a lattice pattern; a drawing mechanism that draws a pattern on the sample by irradiating the plurality of drawing grids, at least some of which are shifted in relative position, with a multibeam; A multi-charged particle beam drawing apparatus comprising:

8. a process of setting a plurality of drawing grids in a drawing region of the sample, the drawing grids being obtained by shifting the relative positions of at least some of the grids from a plurality of ideal grids arranged at equal pitches in a lattice pattern; a process of storing the set plurality of drawing grids in a storage device; a process of reading out the plurality of drawing grids from the storage device, and causing a drawing mechanism to draw a pattern on the sample by using a multibeam to irradiate the plurality of drawing grids, at least some of which have been shifted in relative position; A program that causes a computer to execute the following.

Images