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

Abstract

To provide a multi-beam drawing device capable of avoiding data processing for defective beam correction not being able to keep up with the drawing processing speed.SOLUTION: A multi-beam drawing device includes a molded aperture array substrate, a defect correction data creation unit that creates defect correction data that defines a dose modulation rate to compensate by distributing the dose at the position of a defective beam, which is always OFF among the multi-charged particle beams, to one or more other pixels by using a dose distribution in which each position of a unit area on the sample surface corresponding to the irradiation area of the entire multi-beam is defined by a uniform dose regardless of the drawing pattern, a dose map creation unit that calculates an individual dose amount according to the drawing pattern for each drawing pattern, a dose correction unit that reads defect correction data from the storage device for each drawing pattern and obtains a dose amount by correcting the individual dose amount at each position on the sample, and a drawing mechanism that draws a drawing pattern on the sample using a corrected dose amount.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One aspect of the present invention relates to a multi-charged particle beam writing apparatus and a multi-charged particle beam writing method, and relates to, for example, a technique for reducing dimensional deviation of a pattern caused by multi-beam writing. [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 mask patterns are written onto mask blanks using an electron beam.

[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 each unblocked beam is reduced in size by an optical system to reduce the mask image, and the beams are deflected by a deflector to be irradiated onto the desired position on the sample.

[0004] In multi-beam lithography, the dose irradiated from each beam is controlled by the irradiation time. However, due to factors such as a failure in the blanking control mechanism, it becomes difficult to control the irradiation time, which can result in a defect beam, where no beam is irradiated and the beam is always OFF. If the required dose is not irradiated onto the sample, there is a problem of shape errors occurring in the pattern formed on the sample. To address this problem, it has been proposed to calculate the dose amount for each pixel according to the desired lithography pattern and then correct the dose shortage in the pixel covered by the always OFF defect beam by distributing it to the surrounding beams (see, for example, Patent Document 1). However, data processing for defect beam correction takes time. This can lead to problems such as data generation not keeping up with the lithography processing speed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-033117 Summary of the Invention [Problem to be solved by the invention]

[0006] One aspect of the present invention provides an apparatus and method that can prevent the data processing for defective beam correction from being unable to keep up with the writing processing speed in multi-beam writing. [Means for solving the problem]

[0007] A multi-charged particle beam writing apparatus according to one aspect of the present invention comprises: a beam forming mechanism for forming multiple charged particle beams; a defect correction data creating unit that creates defect correction data defining a dose modulation rate for correcting a dose of a defect beam, which is always turned off among the multi-charged particle beams, at a position assigned to the defect beam by a dose distribution defined by a uniform dose amount at each position of a unit area on a sample surface corresponding to an irradiation area of ​​the entire multi-charged particle beam regardless of a drawing pattern to be drawn, by distributing the dose of the defect beam to one or more other pixels; a storage device that stores defect correction data; a dose calculation unit that calculates, for each drawing pattern, an individual dose at each position on the sample according to the drawing pattern; a dose correction unit that reads defect correction data from the storage device for each writing pattern, corrects the individual dose at each position on the sample according to the writing pattern by dose distribution using a value obtained by multiplying the individual dose at each position on the sample by a dose modulation rate defined in the read defect correction data, and obtains the corrected dose; a drawing mechanism that draws the drawing pattern on the sample using the multi-charged particle beam irradiated with the corrected dose; The present invention is characterized by the following.

[0008] In addition, it is preferable that the defect correction data creation unit inputs positional deviation correction data for correcting individual positional deviations at each irradiation position of the multi-charged particle beam, and further uses the positional deviation correction data to create the defect correction data.

[0009] The pattern is written on the sample by multiple writing, The defect correction data creating unit preferably creates defect correction data so that correction of the dose at a position covered by a defect beam performed in one of a plurality of passes of multiple writing is performed in another pass.

[0010] Furthermore, it is preferable that the defect correction data creating unit creates defect correction data so that correction of the dose at the position covered by the defect beam is performed by a peripheral beam that irradiates positions around the position covered by the defect beam.

[0011] A multi-charged particle beam writing method according to one aspect of the present invention includes: forming a multi-charged particle beam; a step of creating defect correction data defining a dose modulation rate for correcting the dose of a position covered by a defect beam that is always turned off among the multi-charged particle beams by distributing the dose to one or more other pixels using a dose distribution defined by a uniform dose amount for each position of a unit area on a sample surface corresponding to an irradiation area of ​​the entire multi-charged particle beam regardless of a drawing pattern to be drawn; storing the defect correction data in a storage device; calculating, for each drawing pattern, an individual dose amount at each position on the sample according to the drawing pattern; a step of reading defect correction data from the storage device for each writing pattern, correcting the individual dose at each position on the sample according to the writing pattern by dose distribution using a value obtained by multiplying the individual dose at each position on the sample by a dose modulation rate defined in the read defect correction data, and obtaining a corrected dose; A step of drawing a drawing pattern on a sample using a multi-charged particle beam irradiated with the corrected dose amount; The present invention is characterized by the following. [Effects of the Invention]

[0012] According to one aspect of the present invention, in multi-beam writing, it is possible to avoid a situation where data processing for defective beam correction cannot keep up with the writing processing speed. [Brief explanation of the drawings]

[0013] [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] FIG. 2 is a diagram for explaining an example of a multi-beam writing method according to the first embodiment. [Figure 7] FIG. 2 is a flowchart showing the main steps of the writing method according to the first embodiment. [Figure 8] 5A and 5B are diagrams for explaining beam positional deviation and positional deviation periodicity in the first embodiment. [Figure 9] FIG. 2 is a diagram for explaining an example of a positional deviation correction method according to the first embodiment. [Figure 10] FIG. 3 is a diagram showing an example of a dose map of a rectangular unit area for defect correction in the first embodiment. [Figure 11] 5A to 5C are diagrams for explaining an example of a technique for performing defect correction in multiple writing according to the first embodiment. [Figure 12] 4A to 4C are diagrams for explaining an example of a technique for performing defect correction using peripheral pixels according to the first embodiment. [Figure 13] FIG. 10 is a diagram for explaining another example of a technique for performing defect correction using peripheral pixels according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] 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.

[0015] 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. The lithography mechanism 150 includes an electron lens column 102 (multi-electron beam column) and a lithography chamber 103. The electron lens column 102 includes 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 deflector 208, and a deflector 209. The lithography chamber 103 includes an XY stage 105. A sample 101, such as a mask blank coated with resist and serving as a target substrate for lithography, is placed on the XY stage 105. The sample 101 may be an exposure mask used in manufacturing a semiconductor device, a semiconductor substrate (silicon wafer) on which the semiconductor device is manufactured, or the like. Further, a mirror 210 for measuring the position of the XY stage 105 is disposed on the XY stage 105. Further, a Faraday cup 106 is disposed on the XY stage 105.

[0016] 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 stage position detector 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 DAC amplifier units 132 and 134, the stage position detector 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 output of the DAC amplifier unit 132 is connected to a deflector 209. The output of the DAC amplifier unit 134 is connected to a deflector 208. The 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 deflector 209 is composed of four or more electrodes, and each electrode is controlled by a deflection control circuit 130 via a DAC amplifier 132. The stage position detector 139 irradiates a mirror 210 on the XY stage 105 with laser light and receives the light reflected from the mirror 210. Then, the position of the XY stage 105 is measured using the principle of laser interference based on information about the reflected light.

[0017] The control computer 110 includes a beam position deviation map generator 50, a position deviation correction data generator 52, a detector 54, an identifier 55, a defect correction data generator 56, a rasterizer 60, a dose map generator 62, a dose corrector 64, an irradiation time calculator 72, and a writing controller 74. Each of the "units" such as the beam position deviation map generator 50, the position deviation correction data generator 52, the detector 54, the identifier 55, the defect correction data generator 56, the rasterizer 60, the dose map generator 62, the dose corrector 64, the irradiation time calculator 72, and the writing controller 74 includes 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 and output to and from the beam position deviation map creation unit 50, position deviation correction data creation unit 52, detection unit 54, identification unit 55, defect correction data creation unit 56, rasterization unit 60, dose map creation unit 62, dose correction unit 64, irradiation time calculation unit 72, and drawing control unit 74, as well as information being calculated, are stored in memory 112 each time.

[0018] Furthermore, drawing data is input from outside the drawing device 100 and stored in the storage device 140. The drawing data usually defines information on a plurality of graphic patterns to be drawn. Specifically, a graphic code, coordinates, size, etc. are defined for each graphic pattern.

[0019] 1 shows the configuration necessary for explaining the first embodiment. The drawing device 100 may also include other configurations that are normally required.

[0020] FIG. 2 is a conceptual diagram showing the configuration of a shaping aperture array substrate in the first embodiment. In FIG. 2, holes (apertures) 22 are formed in a matrix of p columns (y direction) by q columns (x direction) (p, q≧2) at a predetermined arrangement pitch on the shaping aperture array substrate 203. In FIG. 2, for example, 512×512 columns of holes 22 are formed in the vertical and horizontal directions (x, y directions). Each hole 22 is formed as a rectangle of the same size and shape. Alternatively, they may be circles of the same diameter. The shaping aperture array substrate 203 (beam forming mechanism) forms multiple beams 20. Specifically, multiple beams 20 are formed by portions of electron beam 200 passing through these multiple holes 22. The arrangement of holes 22 is not limited to the grid-like arrangement shown in FIG. 2. For example, the holes in the kth column in the vertical direction (y direction) and the k+1th column in the horizontal direction (x direction) may be offset by a dimension a from each other. Similarly, the holes in the k+1th column and the k+2th column in the vertical direction (y direction) may be arranged with a shift of dimension b in the horizontal direction (x direction).

[0021] FIG. 3 is a cross-sectional view showing the configuration of the blanking aperture array mechanism according to the first embodiment. In the blanking aperture array mechanism 204, as shown in FIG. 3, a semiconductor substrate 31 made of silicon or the like is placed on a support base 33. The central portion of the substrate 31 is removed, for example, from the backside, to form a membrane region 330 (first region) with a thin film thickness h. The area surrounding the membrane region 330 is a peripheral region 332 (second region) with a thick film thickness H. The upper surfaces of the membrane region 330 and the peripheral region 332 are formed to be at the same height position or substantially at the same height position. The substrate 31 is held on the support base 33 at the backside of the peripheral region 332. The central portion of the support base 33 is open, and the membrane region 330 is located in the open region of the support base 33.

[0022] In the membrane region 330, passage holes 25 (openings) for passing through each beam of the multibeam 20 are opened at positions corresponding to the holes 22 of the shaping aperture array substrate 203 shown in FIG. 2. In other words, a plurality of passage holes 25 for passing through corresponding beams of the multibeam 20 using electron beams are formed in an array in the membrane region 330 of the substrate 31. A plurality of electrode pairs, each having two electrodes, are arranged on the membrane region 330 of the substrate 31 at positions facing each other across a corresponding passage hole 25 among the plurality of passage holes 25. Specifically, on the membrane region 330, as shown in FIG. 3, pairs of a control electrode 24 for blanking deflection and a counter electrode 26 (blankers: blanking deflectors) are arranged in positions near each passage hole 25 on either side of the corresponding passage hole 25. Furthermore, a control circuit 41 (logic circuit) for applying a deflection voltage to the control electrode 24 for each passage hole 25 is arranged inside the substrate 31 and near each passage hole 25 on the membrane region 330. The counter electrode 26 for each beam is connected to ground.

[0023] 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 is disposed. The CMOS inverter circuit is connected to a positive potential (Vdd: blanking potential: first potential) (e.g., 5 V) (first potential) and a ground potential (GND: second potential). An output line (OUT) of the CMOS inverter circuit is connected to a control electrode 24. On the other hand, a ground potential is applied to the counter electrode 26. A plurality of control electrodes 24, to which a blanking potential and a ground potential are switchably applied, are disposed on the substrate 31 at positions facing the corresponding counter electrodes 26 of the plurality of counter electrodes 26 across the corresponding passage holes 25 of the plurality of passage holes 25.

[0024] To the input (IN) of the CMOS inverter circuit, either an L (low) potential (e.g., ground potential) lower than the threshold voltage or an H (high) potential (e.g., 1.5 V) 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 becomes a positive potential (Vdd), and a corresponding one of the multi-beams 20 is deflected by an electric field due to a potential difference with the ground potential of the counter electrode 26, and is controlled so that the beam is turned OFF by being blocked 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 counter electrode 26, so that the corresponding one of the multi-beams 20 is not deflected, and the beam is controlled so that it passes through the limiting aperture substrate 206 and is turned ON.

[0025] Each electron beam in the multi-beams 20 passing through each passage hole is deflected by a voltage applied to two independent pairs of control electrodes 24 and counter electrodes 26. Blanking control is performed by this deflection. Specifically, the pairs of control electrodes 24 and counter electrodes 26 individually blank and deflect the corresponding beams in the multi-beams 20 by the potentials switched by the CMOS inverter circuits that serve as corresponding switching circuits. In this way, the multiple blankers perform blanking deflection of the corresponding beams in the multi-beams 20 that have passed through the multiple holes 22 (openings) in the shaping aperture array substrate 203.

[0026] FIG. 4 is a conceptual diagram illustrating an example of the writing operation in the first embodiment. As shown in FIG. 4, the writing region 30 on the sample 101 is virtually divided into a plurality of stripe regions 32, each having a predetermined width in the y direction. First, the XY stage 105 is moved to adjust the irradiation region 34 that can be irradiated with one shot of the multi-beam 20 to be located at the left end of the first stripe region 32 or further to the left, and writing begins. When writing the first stripe region 32, the XY stage 105 is moved, for example, in the −x direction to relatively write in the x direction. The XY stage 105 is moved continuously, for example, at a constant speed. After writing the first stripe region 32, the stage position is moved in the −y direction to adjust the irradiation region 34 to be located at the right end of the second stripe region 32 or further to the right in the y direction. Then, the XY stage 105 is moved, for example, in the x direction to similarly write in the −x direction. The writing time can be reduced by alternately changing the writing direction, such as writing in the x direction in the third stripe region 32 and writing in the -x direction in the fourth stripe region 32. However, writing is not limited to alternately changing the writing direction, and writing in each stripe region 32 may proceed in the same direction. In one shot, multiple shot patterns, up to the same number as the number of holes 22 formed in the shaping aperture array substrate 203, are formed at once by the multi-beams formed by passing through each hole 22 in the shaping aperture array substrate 203. Furthermore, while the example in FIG. 4 shows a case where each stripe region 32 is written once, this is not limiting. Multiple writing, in which the same region is written multiple times, is also suitable. When performing multiple writing, it is suitable to set the stripe regions 32 for each pass while shifting their positions.

[0027] FIG. 5 is a diagram showing an example of a multi-beam irradiation region and a pixel to be written in the first embodiment. In FIG. 5, a plurality of control grids 27 (design grids) are set in the stripe region 32, for example, arranged in a grid pattern at a beam size pitch of the multi-beams 20 on the surface of the sample 101. The control grids 27 preferably have an arrangement pitch of, for example, about 10 nm. The plurality of control grids 27 are the designed irradiation positions of the multi-beams 20. The arrangement pitch of the control grids 27 is not limited to the beam size, and may be any size that can be controlled as the deflection position of the deflector 209, regardless of the beam size. A plurality of pixels 36 are set, virtually divided into a mesh shape with the same size as the arrangement pitch of the control grids 27, with each control grid 27 at its center. Each pixel 36 is an irradiation unit region for one beam of the multi-beams. The example of FIG. 5 shows a case where the writing area of ​​the sample 101 is divided, for example, in the y direction, into multiple stripe regions 32 each having a width substantially equal to the size of the irradiation area 34 (writing field) that can be irradiated with one shot of the multibeam 20 (beam array). The x-direction size of the irradiation area 34 can be defined as the value obtained by multiplying the inter-beam pitch of the multibeam 20 in the x direction by the number of beams in the x direction. The y-direction size of the irradiation area 34 can be defined as the value obtained by multiplying the inter-beam pitch of the multibeam 20 in the y direction by the number of beams in the y direction. Note that the width of the stripe regions 32 is not limited to this. Preferably, the size is n times the size of the irradiation area 34 (n is an integer greater than or equal to 1). In the example of FIG. 5, for example, a 512 × 512 array of multibeams is shown as an 8 × 8 array of multibeams. Furthermore, within the irradiation area 34, multiple pixels 28 (beam writing positions) that can be irradiated with one shot of the multibeam 20 are shown. In other words, the pitch between adjacent pixels 28 is the pitch between each beam of the designed multi-beam. In the example of Fig. 5, the area surrounded by the inter-beam pitch constitutes one sub-illumination area 29. In the example of Fig. 5, each sub-illumination area 29 is composed of 4 x 4 pixels.

[0028] FIG. 6 is a diagram illustrating an example of a multi-beam writing method according to the first embodiment. FIG. 6 illustrates a portion of the sub-irradiation region 29 written by each beam at coordinates (1,3), (2,3), (3,3), . . . , (512,3) in the k-th stage in the y-direction, among the multi-beams that write the stripe region 32 shown in FIG. 5 . The example in FIG. 6 illustrates a case in which, for example, four pixels are written (exposed) while the XY stage 105 moves a distance equivalent to eight beam pitches. While writing (exposing) these four pixels, the entire multi-beam 20 is deflected collectively by the deflector 208 so that the relative position of the irradiation region 34 with respect to the sample 101 does not shift due to the movement of the XY stage 105. This causes the irradiation region 34 to follow the movement of the XY stage 105. In other words, tracking control is performed. The example in FIG. 6 illustrates a case in which one tracking cycle is performed by writing (exposing) four pixels while moving a distance equivalent to eight beam pitches.

[0029] Specifically, in each shot, a beam is irradiated for a writing time (irradiation time or exposure time) corresponding to each control grid 27 within the set maximum writing time. Specifically, each control grid 27 is irradiated with a corresponding ON beam among the multi-beams 20. Then, for each shot cycle time Ttr, which is the maximum writing time plus the settling time of the DAC amplifier, the irradiation position of each beam is moved to the next shot position by collective deflection by the deflector 209.

[0030] 6, when four shots have been taken, the DAC amplifier unit 134 resets the beam deflection for tracking control, thereby returning the tracking position to the tracking start position where tracking control was started.

[0031] Note that drawing of the first pixel row from the right in each sub-irradiation area 29 has been completed. Therefore, after tracking reset, in the next tracking cycle, the deflector 209 first deflects the beams so as to align (shift) the drawing positions of the corresponding beams with the control grid 27 of the pixel in the first row from the bottom and second from the right in each sub-irradiation area 29. By repeating this operation, drawing of all pixels is completed. If the sub-irradiation area 29 is made up of n x n pixels, n tracking operations are performed, each time with a different beam, to draw n pixels. In this way, all pixels in one n x n pixel area are drawn. Similar operations are performed at the same time for other n x n pixel areas within the multi-beam irradiation area, and drawing is performed in the same manner.

[0032] Next, the operation of the drawing mechanism 150 in the drawing apparatus 100 will be described. An electron beam 200 emitted from an electron gun 201 (emission source) illuminates the entire shaping aperture array substrate 203 via an illumination lens 202. A plurality of rectangular holes 22 (openings) are formed in the shaping aperture array substrate 203. The electron beam 200 then 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 in the shaping aperture array substrate 203, respectively. This results in the formation of a plurality of electron beams (multibeams 20) each having a rectangular shape. The multibeams 20 pass through corresponding blankers (first deflectors: individual blanking mechanisms) in a blanking aperture array mechanism 204. Each blanker individually deflects the passing electron beam (performs blanking deflection).

[0033] The multi-beams 20 passing through the blanking aperture array mechanism 204 are reduced by the reduction lens 205 and travel toward the central hole formed in the limiting aperture substrate 206. Here, the electron beams of the multi-beams 20 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 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 . Blanking control is performed by turning on / off the individual blanking mechanisms, and the beams are turned on / off. In this way, the limiting aperture substrate 206 blocks each beam deflected by the individual blanking mechanisms to turn the beam off. Then, the beams formed for each beam, which have passed through the limiting aperture substrate 206 from when the beam is turned on until when the beam is turned off, form a single shot of beam. 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 individual beams that have passed through the limiting aperture substrate 206 (the entire multibeams 20 that have passed through) are deflected collectively in the same direction by the deflectors 208 and 209, and each beam is irradiated onto its respective irradiation position on the sample 101. Ideally, the multibeams 20 that are irradiated at one time are aligned 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] As described above, defective beams can occur in multi-beams. Defective beams include over-dose defective beams, which are beams that are irradiated with an excessive dose because the beam dose cannot be controlled, and under-dose defective beams, which are beams that are irradiated with an insufficient dose because the beam dose cannot be controlled. Over-dose defective beams include ON defect beams that are always ON and a portion of poorly controlled defect beams that are poorly controlled for irradiation time. Under-dose defective beams include OFF defect beams that are always OFF and the remainder of poorly controlled defect beams.

[0035] If the defect beam does not irradiate the sample with the expected dose, shape errors can occur in the pattern formed on the sample. To address this issue, conventional methods calculate the dose for each pixel according to the desired pattern. Then, the dose for the pixel assigned to the defect beam is calculated relative to the dose for each pixel. A distribution ratio is then calculated to distribute the calculated dose to the surrounding beams. The dose for each pixel is then modulated according to the distribution ratio. Such correction methods have been considered. However, data processing for defect beam correction takes time. This can lead to problems such as data generation not keeping up with the writing processing speed. Furthermore, when the writing pattern to be written changes, the dose for each pixel according to the writing pattern must be calculated again in order to determine the distribution ratio for distribution to the surrounding beams. Thus, every time the writing pattern changes, data processing must be restarted from scratch to determine the distribution ratio for distribution to the surrounding beams.

[0036] Here, for defect beams other than those that are always OFF, it is unclear whether the dose is insufficient or excessive unless the design dose corresponding to the drawing pattern is determined. To correct the excessive dose, the dose of the surrounding beams is reduced. Therefore, pixels without a pattern and with a design dose of zero cannot be further reduced and therefore cannot be used for defect correction. Therefore, it is difficult to determine the distribution ratio for distributing to the surrounding beams without using a drawing pattern. In contrast, for defect beams that are always OFF, the irradiated dose is zero, so the dose of the surrounding beams must be increased when performing defect correction. Therefore, even pixels without a pattern and with a design dose of zero can be used for defect correction. Therefore, it may be possible to independently determine the distribution ratio for distributing to the surrounding beams regardless of the drawing pattern.

[0037] Therefore, in the first embodiment, for the defect beams that are always OFF, a distribution ratio for distributing the insufficient dose to the surrounding beams is calculated regardless of the drawing pattern as a preprocessing before starting the drawing process. Then, defect correction data that defines the distribution ratio for each distribution destination of each pixel is created in advance. Then, in the actual drawing process, dose modulation for each pixel is performed for each drawing pattern by using the defect correction data that has already been created and is independent of the drawing pattern. This will be explained in detail below.

[0038] FIG. 7 is a flowchart showing the main steps of the writing method according to the first embodiment. In FIG. 7, the writing method according to the first embodiment performs a series of steps, including a beam position deviation amount measuring step (S102), a defect beam detecting step (S104), a position deviation correction data creating step (S106), a defect beam position specifying step (S108), a defect correction data creating step (S110), a dose amount calculating step (S120), a dose correcting step (S130), an irradiation time calculating step (S140), and a writing step (S142). In the first embodiment, a case where beam position deviation correction is also performed in addition to defect beam correction will be described, but the present invention is not limited to this. When beam position deviation correction is not performed, the beam position deviation amount measuring step (S102) and the position deviation correction data creating step (S106) may be omitted.

[0039] The beam position deviation amount measuring process (S102), the defective beam detection process (S104), the position deviation correction data creating process (S106), the defective beam position identifying process (S108), and the defect correction data creating process (S110) are each performed as pre-processing before starting the drawing process.

[0040] In the beam position deviation amount measuring step (S102), the drawing apparatus 100 measures the amount of deviation of the irradiation position of each beam of the multibeam 20 on the surface of the sample 101 from the corresponding control grid 27.

[0041] FIG. 8 is a diagram illustrating the beam positional deviation and positional deviation periodicity in the first embodiment. In the multi-beam 20, as shown in FIG. 8( a), distortion occurs in the exposure field due to the characteristics of the optical system. This distortion causes the actual irradiation positions 39 of each beam to deviate from the irradiation positions 37 when the beam is irradiated onto an ideal grid. Therefore, in the first embodiment, the amount of positional deviation of the actual irradiation positions 39 of each beam is measured. Specifically, the multi-beam 20 is irradiated onto a resist-coated evaluation substrate, and the position of the resist pattern generated by developing the evaluation substrate is measured using a position measuring device. This allows the amount of positional deviation for each beam to be measured. If it is difficult to measure the size of the resist pattern at the irradiation position of each beam using a position measuring device for the shot size of each beam, a figure pattern (e.g., a rectangular pattern) of a size measurable by the position measuring device is written using each beam. Then, the edge positions of both sides of the figure pattern (resist pattern) (both left and right sides or both upper edges of the rectangular pattern) are measured, and the amount of positional deviation of the target beam can be measured from the difference between the midpoint between the two edges and the midpoint of the designed figure pattern. The obtained misalignment data of the irradiation position of each beam is input to the writing device 100 and stored in the storage device 144. Furthermore, in multi-beam writing, writing progresses while shifting the irradiation region 34 within the stripe region 32. For example, in the writing sequence described with reference to FIG. 6, the positions of the irradiation regions 34 move sequentially from 34a to 34o during writing of the stripe region 32, as shown in the lower part of FIG. 4. Periodicity occurs in the misalignment of each beam with each movement of the irradiation region 34. Alternatively, in the case of a writing sequence in which each beam irradiates all pixels 36 within the corresponding sub-irradiation region 29, periodicity occurs in the misalignment of each beam for each unit region 35 (35a, 35b, ...) that is at least the same size as the irradiation region 34, as shown in FIG. 8(b). Therefore, if the misalignment amount of each beam for the irradiation region 34 of the beam array is measured, the measurement result can be reused. In other words, it is sufficient to measure the misalignment amount of each beam at each pixel 36 within the corresponding sub-irradiation region 29.

[0042] The beam position deviation map creation unit 50 then first creates a beam position deviation map (1) that defines the amount of deviation of each beam for each pixel 36 in a beam array unit, in other words, within one rectangular unit area 35 (an example of a unit area) on the sample surface corresponding to the irradiation area 34. The rectangular unit area 35 corresponds to the irradiation area 34 of the multibeam 20, which is a combination of designed sub-irradiation areas 29 (small areas) in which each beam of the multibeam 20 is surrounded by multiple adjacent beams on the sample surface. Here, the unit area is rectangular because the multibeam 20 is arranged in a square lattice pattern, but the shape of the unit area may vary depending on the arrangement shape of the multibeam 20. Specifically, the beam position deviation map creation unit 50 reads out deviation data of the irradiation position of each beam from the storage device 144 and creates the beam position deviation map (1) using the data as map values. Which beam of the entire multibeam 20 irradiates the control grid 27 of each pixel 36 in one rectangular unit area 35 on the sample surface corresponding to the irradiation area 34 irradiated by the entire multibeam 20 is determined by the writing sequence, for example, as described in FIG. 6. Therefore, the beam position deviation map creation unit 50 identifies the beam responsible for irradiating the control grid 27 of each pixel 36 in one unit area 35 in accordance with the writing sequence, and calculates the amount of position deviation of that beam. The created beam position deviation amount map (1) is stored in the storage device 144.

[0043] In the defect beam detection step (S104), the detection unit 54 detects defect beams from the multi-beams 20. An ON defect beam that is always ON always irradiates the beam for the maximum irradiation time per shot, regardless of the controlled dose. Alternatively, irradiation continues even when moving between pixels. An OFF defect beam that is always OFF always remains OFF, regardless of the controlled dose. Specifically, under the control of the writing control unit 74, the writing mechanism 150 controls each of the multi-beams 20 to be turned ON by the blanking aperture array mechanism 204, and controls all the remaining beams to be turned OFF. In this state, a beam for which no current is detected by the Faraday cup 106 is detected as an OFF defect beam. Conversely, from this state, the control is switched so that the beam to be detected is turned OFF. At this time, a beam for which a current is always detected by the Faraday cup 106 despite switching from ON to OFF is detected as an ON defect beam. After switching from beam ON to beam OFF, a beam in which current is detected by the Faraday cup 106 for a predetermined period of time is detected as a poorly controlled defective beam. By checking all beams in the multi-beam 20 in order using the same method, it is possible to detect the presence or absence of a defective beam, its type, and the position of the defective beam. Here, the case where defective beams other than OFF defective beams are also detected is described, but it is also possible to only detect OFF defective beams that are always OFF. Information on the detected defective beams is stored in the memory device 144.

[0044] In the positional deviation correction data creating step (S106), the positional deviation correction data creating unit 52 creates positional deviation correction data for correcting individual positional deviations of the irradiation positions of the multi-beams 20.

[0045] FIG. 9 is a diagram illustrating an example of a misalignment correction method according to the first embodiment. The example in FIG. 9(a) illustrates a case where a beam a' irradiated onto a pixel at coordinates (x, y) is misaligned toward the -x, -y side. To correct the misalignment of a pattern formed by the misaligned beam a' to a position that matches the pixel at coordinates (x, y) as shown in FIG. 9(b), the misalignment can be corrected by distributing the dose of irradiation corresponding to the misalignment to pixels on the opposite side of the direction of the surrounding pixels. In the example in FIG. 9(a), the dose of irradiation corresponding to the misalignment of the pixel at coordinates (x, y-1) may be distributed to the pixel at coordinates (x, y+1). The dose of irradiation corresponding to the misalignment of the pixel at coordinates (x-1, y) may be distributed to the pixel at coordinates (x+1, y). The dose of irradiation corresponding to the misalignment of the pixel at coordinates (x-1, y-1) may be distributed to the pixel at coordinates (x+1, y+1).

[0046] In the first embodiment, a misalignment correction distribution amount is calculated that distributes the irradiation amount to the beam for at least one surrounding pixel in proportion to the amount of beam misalignment. The misalignment correction data creation unit 52 calculates the modulation rate of the beam for the pixel and the modulation rate of the beam for at least one pixel surrounding the pixel in accordance with the ratio of the area shifted due to the beam misalignment for the pixel. Specifically, for each surrounding pixel where the beam is shifted from the pixel of interest and part of the beam overlaps, the ratio of the shifted area (area of ​​the overlapping beam part) divided by the beam area is calculated as the distribution amount (beam modulation rate) for the pixel located on the opposite side of the pixel of interest from the overlapping pixel.

[0047] 9(a), the area ratio shifted to the pixel at coordinate (x, y-1) can be calculated by (x-direction beam size - (-x) direction shift amount) x y-direction shift amount / (x-direction beam size x y-direction beam size). Therefore, the distribution amount (beam modulation rate) V to be distributed to the pixel at coordinate (x, y+1) for correction can be calculated by (x-direction beam size - (-x) direction shift amount) x y-direction shift amount / (x-direction beam size x y-direction beam size).

[0048] 9(a), the area ratio shifted to the pixel at coordinates (x-1, y-1) can be calculated by the formula: -x direction shift amount × -y direction shift amount / (x direction beam size × y direction beam size). Therefore, the distribution amount (beam modulation rate) W to be distributed to the pixel at coordinates (x+1, y+1) for correction can be calculated by the formula: -x direction shift amount × -y direction shift amount / (x direction beam size × y direction beam size).

[0049] In the example of Figure 9(a), the area ratio shifted to the pixel at coordinate (x-1, y) can be calculated by the -x direction shift amount × (y direction beam size - (-y) direction shift amount) / (x direction beam size × y direction beam size). Therefore, the distribution amount (beam modulation rate) Z to be distributed to the pixel at coordinate (x+1, y) for correction can be calculated by the -x direction shift amount × (y direction beam size - (-y) direction shift amount) / (x direction beam size × y direction beam size).

[0050] As a result, the remaining portion that has not been distributed, that is, the modulation factor U of the beam of the pixel at coordinates (x, y), can be calculated by 1-VWZ.

[0051] In this manner, for each pixel 36 in a beam array unit, in other words, a rectangular unit area 35 on the sample surface corresponding to the irradiation area 34, the modulation rate of the beam to that pixel and the modulation rate of the beam to at least one surrounding pixel to which the beam is distributed are calculated. Then, the positional deviation correction data creation unit 52 creates positional deviation correction data for each pixel 36, in which the modulation rate of the beam to that pixel and the modulation rate of the beam to at least one surrounding pixel to which the beam is distributed are defined. The positional deviation correction data is created for one rectangular unit area 35 on the sample surface corresponding to the irradiation area 34. The created positional deviation correction data is stored in the storage device 144.

[0052] In the defect beam position identifying step (S108), the identifying unit 55 identifies, for each beam array unit, in other words, for each pixel 36 in one rectangular unit area 35 on the sample surface corresponding to the irradiation area 34, a pixel to be irradiated by a defect beam that is always OFF among the defect beams. As described above, which beam irradiates the control grid 27 of each pixel 36 in the rectangular unit area 35 is determined by the writing sequence.

[0053] In the defect correction data creation process (S110), the defect correction data creation unit 56 creates defect correction data that defines a dose modulation rate for correcting the dose at a position covered by a defect beam among the multi-beams 20 that is always beam-off, by distributing it to one or more other pixels, using a dose distribution defined by a uniform dose amount for each beam array unit, in other words, for each pixel 36 of one rectangular unit area 35 on the sample surface corresponding to the irradiation area 34, regardless of the drawing pattern to be drawn.

[0054] 10 is a diagram showing an example of a dose map of a rectangular unit area for defect correction in the first embodiment. As shown in FIG. 10, it is preferable to use a 100% dose with respect to a reference dose as the dose amount for each pixel. In other words, it is assumed that the entire rectangular unit area 35 is a so-called solid pattern. Since the entire rectangular unit area 35 is a so-called solid pattern, it does not depend on the drawing pattern that is actually drawn.

[0055] In the example of FIG. 6 , the XY stage 105 moves 32 beam pitches (= 4 times × 8 beam pitches) in the −x direction during four tracking operations. One drawing process is performed during this 32 beam pitch movement. In this configuration, when drawing is performed on a beam array unit, in other words, on the entire rectangular unit area 35 on the sample surface corresponding to the irradiation area 34, with 512 × 512 multibeams, multiple drawing (multiplicity = 16) is performed for each pixel 36 through 16 (= 512 / 32) drawing processes (passes). When drawing is performed with 32 × 32 multibeams 20, one drawing process (pass) is performed for each pixel. Furthermore, if the XY stage 105 is continuously moved, for example, four times, multiple drawing (multiplicity = 4) is performed for each pixel 36 through four drawing processes (passes). Note that in the first embodiment, the number of stage movements is referred to as a pass, not each drawing process of the multiple drawing.

[0056] FIG. 11 is a diagram illustrating an example of a defect correction technique in multiple lithography according to the first embodiment. The example in FIG. 11 illustrates a case where multiple lithography is performed using four lithography processes (passes). Each pixel is irradiated with, for example, four different beams. The dose T(x) for each pixel is divided into 1 / 4 for each pass. Therefore, pixels not covered by the defect beam are irradiated with a dose of T(x) / pass per lithography, as shown in FIG. 11(a). For pixels covered by the defect beam, the defect beam is responsible for one of the four irradiations. Since the beam is not irradiated in the pass covered by the defect beam, the dose for one lithography pass is insufficient. Therefore, when a lithography pattern is lithographed on a sample by multiple lithography, the defect correction data creation unit 56 creates defect correction data so that the dose correction for a position covered by the defect beam, which is performed in one of the multiple passes of multiple lithography, is performed in another pass. For example, as shown in FIG. 11(b), defect correction data is created so that the distributed dose (shortfall) obtained by dividing the dose for one pass by the number of other passes is added evenly to the other passes. In the example of FIG. 11(b), 33% of a 25% dose is distributed. The distribution method is not limited to even distribution. It may be distributed unevenly to some passes. If the distribution is uneven, the dose may become too large for some passes. In that case, the maximum irradiation time will increase, leading to an increase in the writing time. Therefore, it is preferable to add it evenly to the other passes. This prevents the maximum irradiation time from becoming too long.

[0057] The defect correction data defines a dose modulation rate of 0% for pixels covered by the defect beam and a dose modulation rate for at least one pass to which the defect beam is distributed. A dose modulation rate of 100%, which is solid data, is defined for other pixels. It is preferable to create defect correction data for each pass. Information on pixels covered by the defect beam is shared between passes.

[0058] As described above, when creating the positional deviation correction data, the defect correction data creation unit 56 inputs the positional deviation correction data for correcting the individual positional deviations of each irradiation position of the multi-beam, and further uses the positional deviation correction data to create the defect correction data. Therefore, for the pixel assigned to the defect beam, a dose modulation rate of 0% for itself and a dose modulation rate for at least one path to which the defect beam is distributed are defined. The dose modulation rate for the path to which the defect beam is distributed is further defined as a value multiplied by each dose modulation rate defined in the positional deviation correction data. For the other pixels, a dose modulation rate of each dose modulation rate defined in the positional deviation correction data x 100% is defined.

[0059] This is not limited to cases where defect correction is performed by distribution to other paths. For example, the defect correction data creation unit 56 creates defect correction data so that correction of the dose at a position covered by a defect beam is performed by a peripheral beam that irradiates positions surrounding the position covered by the defect beam.

[0060] FIG. 12 is a diagram illustrating an example of a defect correction method using peripheral pixels according to the first embodiment. The defect correction data generator 56 distributes the dose of the defect beam to at least one, for example, three or more, peripheral pixels around the control grid 10 of the pixel covered by the defect beam. The example in FIG. 12 illustrates a case in which the dose is distributed to the peripheral pixel of irradiation position 39a, the peripheral pixel of irradiation position 39c, and the peripheral pixel of irradiation position 39g. It is preferable to use three or more irradiation positions surrounding the control grid 10 of the pixel covered by the defect beam. In the first embodiment, it is preferable to determine the distribution ratios so that the center of gravity of the multiple distribution ratios (dose modulation ratios) is located at the position of the control grid 10 of the pixel covered by the defect beam. In this case, the distribution ratios are determined according to the distance ri from the control grid 10 to the irradiation position of the peripheral beam. i represents the index of the target peripheral beam among the group of N peripheral beams. In this case, each distribution ratio δdi can be defined, for example, by the following equation (1) using the 100% dose Δ and the distance ri:

[0061]

number

[0062] As shown in FIG. 12, the target irradiation position 39g may be outside the pattern. If a dose distribution corresponding to the lithography pattern is created first, it is possible to determine whether the irradiation position of each pixel is inside or outside the pattern. Therefore, the dose corresponding to the lithography pattern is zero for pixels at irradiation positions outside the pattern, allowing for adjustments such as increasing the dose distributed for defect correction. If deviations in the center of gravity position can be tolerated, adjustments can be made, for example, to 5% for two pixels within the pattern and 80% for one pixel outside the pattern. This prevents the creation of pixels with excessively large final doses. However, in the first embodiment, defect correction is performed regardless of the lithography pattern, so it is unclear at the time of calculating the distribution rate for defect correction whether the target irradiation position is inside or outside the pattern. Therefore, adjusting the distribution rate depending on whether it is inside or outside the pattern is difficult. Therefore, it is preferable to set an upper limit on the distribution rate. For example, it is preferable to set the upper limit to approximately 40%. It is also preferable to set the upper limit to the maximum value of the sum (total modulation rate) of the dose modulation rate of the pixel for which the positional deviation correction is performed and the dose modulation rates distributed from other pixels. This makes it possible to avoid pixels with an excessively large dose. Therefore, it is possible to suppress an increase in the maximum irradiation time. As a result, it leads to a reduction in the writing time.

[0063] Fig. 13 is a diagram for explaining another example of the technique for performing defect correction using peripheral pixels according to the first embodiment. If the distribution rate of the distribution destination exceeds a set upper limit, the number of distribution destinations can be increased as shown in Fig. 13. The example in Fig. 13 shows a case where distribution is performed to 11 pixels.

[0064] Furthermore, although this will result in a deterioration in accuracy, if the deviation of the center of gravity position is not taken into consideration, the distribution rate δd may be determined by equation (2) simply dividing the 100% dose amount Δ by the number N of distribution destinations.

[0065]

number

[0066] The defect correction data defines a dose modulation rate of 0% for the pixel that the defect beam is responsible for and a distribution rate (dose modulation rate) for at least one pixel to which the beam is distributed. For other pixels, a dose modulation rate of 100% is defined, which is solid data.

[0067] As described above, when misalignment correction data is created, the defect correction data creation unit 56 inputs misalignment correction data for correcting the individual misalignments of each irradiation position of the multi-beams, and further uses the misalignment correction data to create the defect correction data. Therefore, for the pixel assigned to the defect beam, a dose modulation rate of 0% is defined for itself, and dose modulation rates for at least one, for example, three or more pixels to which the defect beam is distributed are defined. Here, it is preferable to align the center of gravity of the dose modulation rates of the distribution destinations, taking misalignment into account, with the position of the pixel assigned to the defect beam. For the other pixels, a dose modulation rate of each dose modulation rate defined in the misalignment correction data multiplied by 100% is defined.

[0068] The created defect correction data is stored in the storage device 144. Note that the defect correction data may be created in consideration of the contents of the misalignment correction data as described above, or may be stored in the storage device 144 as separate data.

[0069] As described above, defect correction data (and positional deviation correction data) that are independent of the drawing pattern are created as preprocessing before the drawing process is started. Next, the drawing process is performed for each drawing pattern.

[0070] Here, the larger of the maximum value (3) of the sum (total modulation rate) of the dose modulation rate of the pixel for each pixel for positional deviation correction and the dose modulation rates distributed from other pixels and the maximum value (2) of the dose modulation rate of the defect correction distributed to each pixel is calculated. If the reference value (4) of the individual dose corresponding to the writing pattern is known, the dose actually irradiated to each pixel will not exceed the product ((3) × (4)) of the two. Therefore, the product of the two is set as the maximum dose ((3) × (4)), and the maximum irradiation time can be calculated by dividing the maximum dose by the current density. If dose modulation such as proximity effect correction is not performed, the reference value (4) of the individual dose can be the reference dose Dbase. If dose modulation such as proximity effect correction is performed, the reference value (4) of the individual dose can be calculated by multiplying the maximum dose modulation rate for proximity effect correction by the reference dose Dbase.

[0071] In the dose calculation step (S120), the dose map creation unit 62 (dose calculation unit) calculates, for each drawing pattern, an individual dose for each pixel 36 on the sample 101 according to the drawing pattern. Specifically, the operation is as follows. First, the rasterization unit 60 reads drawing data from the storage device 140, and calculates, for each pixel 36, the pattern area density ρ′ within the pixel 36. This process is performed, for example, for each stripe region 32.

[0072] Next, the dose map creation unit 62 first virtually divides the writing region (here, for example, the stripe region 32) into a plurality of proximity mesh regions (mesh regions for calculating proximity effect correction) in a mesh shape with a predetermined size. The size of the proximity mesh region is preferably set to about 1 / 10 of the range of influence of the proximity effect, for example, about 1 μm. The dose map creation unit 62 reads the writing data from the storage device 140, and calculates, for each proximity mesh region, the pattern area density ρ of the pattern to be arranged in the proximity mesh region.

[0073] Next, the dose map creation unit 62 calculates a proximity effect correction irradiation coefficient Dp(x) (corrected dose) for correcting the proximity effect for each proximity mesh region. The unknown proximity effect correction irradiation coefficient Dp(x) can be defined by a threshold model for proximity effect correction similar to the conventional method, using the backscattering coefficient η, the dose threshold Dth of the threshold model, the pattern area density ρ, and the distribution function g(x).

[0074] Next, the dose map creation unit 62 calculates, for each pixel 36, an incident irradiation dose D(x) (dose) for irradiating the pixel 36. The incident irradiation dose D(x) may be calculated, for example, as a value obtained by multiplying a preset reference irradiation dose Dbase by a proximity effect correction irradiation coefficient Dp and a pattern area density ρ'. The reference irradiation dose Dbase can be defined, for example, as Dth / (1 / 2 + η). In this way, the original desired incident irradiation dose D(x) with the proximity effect corrected can be obtained based on the layout of the multiple graphic patterns defined in the drawing data.

[0075] Then, the dose map creation unit 62 creates a dose map that defines the incident irradiation dose D(x) for each pixel 36 in stripe units. The incident irradiation dose D(x) for each pixel 36 is the incident irradiation dose D(x) that is intended to be applied to the control grid 27 of that pixel 36 in terms of design. In other words, the dose map creation unit 52 creates a dose map that defines the incident irradiation dose D(x) for each control grid 27 in stripe units. The created dose map is stored in, for example, the storage device 144.

[0076] In the dose correction process (S130), the dose correction unit 64 reads defect correction data from the storage device 144 for each drawing pattern, corrects the individual dose amount at each position on the sample according to the drawing pattern by dose distribution using a value obtained by multiplying the individual dose amount at each position on the sample by the dose modulation rate defined in the read defect correction data, and obtains the corrected dose amount.

[0077] Specifically, the dose correction unit 64 first repeatedly allocates rectangular unit areas 35 to the stripe area 32 in accordance with the writing sequence, thereby specifying which beam will irradiate each pixel 36 in the stripe area 32.

[0078] The dose correction unit 64 calculates, for each pixel, a value obtained by multiplying the individual dose of each pixel according to the drawing pattern by the dose modulation rate of the pixel defined in the defect correction data. The dose correction unit 64 also calculates, for each pixel, a value obtained by multiplying the individual dose of each pixel according to the drawing pattern by the dose modulation rate for the distribution destination pixel defined in the defect correction data, and distributes the calculated value to the distribution destination pixel. Next, the dose correction unit 64 sums, for each pixel 36, the dose obtained by multiplying the dose modulation rate of the pixel and the distributed dose. If a pixel assigned to the defect beam contains doses distributed from other pixels, the total dose will not be zero. In this case, the dose correction unit 64 calculates, for the pixel assigned to the defect beam, a value obtained by multiplying the total dose by the dose modulation rate (0%) of the pixel defined in the defect correction data. It is preferable to exclude the defect beam from the dose distribution destinations in advance when creating the defect correction data.

[0079] When the defect correction data and the misalignment correction data are stored separately, the dose correction unit 64 first calculates a value obtained by multiplying the individual dose of each pixel according to the writing pattern by the dose variation rate for that pixel defined in the misalignment correction data. The dose correction unit 64 then calculates a value obtained by multiplying the individual dose of that pixel by the dose modulation rate for the distribution destination pixel defined in the defect correction data, and distributes the calculated value to the distribution destination pixel. The dose correction unit 64 then sums the dose obtained by multiplying the dose variation rate for that pixel by the dose variation rate for that pixel for each pixel 36 and the distributed dose. Next, the dose correction unit 64 calculates a value obtained by multiplying the individual summed dose of each pixel by the dose variation rate for that pixel defined in the defect correction data. The dose correction unit 64 then calculates a value obtained by multiplying the summed individual dose of that pixel by the dose modulation rate for the distribution destination pixel defined in the defect correction data, and distributes the calculated value to the distribution destination pixel. Then, the dose correction unit 64 adds up the distributed dose to the dose obtained by multiplying the dose variation rate of the pixel for each pixel 36. It is also preferable to combine the defect correction data and the misalignment correction data in advance and perform the defect correction and misalignment correction together at one time.

[0080] In the flowchart shown in Figure 7, correction is not performed for defect beams other than the constantly OFF defect beam. However, this is not limited to this. Correction for excess dose irradiated by an excess dose defect beam such as a constantly ON defect beam may also be performed. The method for correcting excess dose may be the same as the conventional method.

[0081] In the irradiation time calculation step (S140), the irradiation time calculation unit 72 calculates the irradiation time t corresponding to the dose of each pixel after the beam positional deviation has been corrected and the underdose due to the defective beam has been corrected. The irradiation time t can be calculated by dividing the dose D by the current density J. The irradiation time t of each pixel 36 (control grid 27) is calculated as a value within the maximum irradiation time Ttr that can be irradiated with one shot of the multi-beam 20. The irradiation time t of each pixel 36 (control grid 27) is converted into grayscale value data of 0 to 1023 grayscales, for example, with the maximum irradiation time Ttr being 1023 grayscales (10 bits). The grayscale irradiation time data is stored in the storage device 142.

[0082] In the writing step (S142), first, the writing control unit 74 rearranges the irradiation time data in shot order according to the writing sequence. Then, the irradiation time data is transferred to the deflection control circuit 130 in shot order. The deflection control circuit 130 outputs a blanking control signal to the blanking aperture array mechanism 204 in shot order, and also outputs a deflection control signal to the DAC amplifier units 132 and 134 in shot order. Then, the writing mechanism 150 writes a writing pattern on the sample 101 using the multi-beam 20 irradiated with the corrected dose.

[0083] As described above, in the first embodiment, defect correction data (and misalignment correction data) that do not depend on the writing pattern are created in advance before starting the writing process. Then, the defect correction data (and misalignment correction data) are used to correct the individual dose amount of each pixel according to the writing pattern for each writing pattern. Even if the writing pattern changes, the defect correction data (and misalignment correction data) that has already been created can be reused. Therefore, there is no need to create the defect correction data (and misalignment correction data) again every time the writing pattern changes. This makes it possible to shorten the data processing time in the writing process.

[0084] Therefore, according to the first embodiment, in multi-beam writing, it is possible to avoid a situation where the data processing for defective beam correction cannot keep up with the writing processing speed.

[0085] The above describes an embodiment with reference to specific examples. However, the present invention is not limited to these specific examples. In the above example, a case has been described in which the irradiation time of each beam of the multi-beam 20 is individually controlled for each beam within the maximum irradiation time Ttr for one shot. However, the present invention is not limited to this. For example, the maximum irradiation time Ttr for one shot is divided into multiple sub-shots with different irradiation times. Then, for each beam, a combination of sub-shots is selected from the multiple sub-shots so that the irradiation time for one shot is achieved. Then, it is also preferable to control the irradiation time for one shot for each beam by continuously irradiating the same pixel with the same beam using the selected combination of sub-shots.

[0086] In the above example, a 10-bit control signal is input to control each control circuit 41, but the number of bits may be set as appropriate. For example, a 2-bit, or 3-9-bit control signal may be used. Note that a control signal of 11 or more bits may also be used.

[0087] 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.

[0088] In addition, all other multi-charged particle beam writing apparatuses and multi-charged particle beam writing methods 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]

[0089] 20 Multibeam 22 holes 24 control electrode 25 Passing hole 26 Counter electrode 27 Control Grid 28 pixels 29 Sub-irradiation area 30 drawing area 32 stripe area 31 PCB 33 Support stand 34 Irradiation area 35 Rectangular unit area 36 pixels 37,39 Irradiation position 41 Control circuit 50 Beam position deviation map creation unit 52 Position deviation correction data creation unit 54 Detection unit 55 Specific part 56 Defect correction data creation unit 60 Rasterization section 62 Dose Map Creation Department 64 Dose correction unit 72 Irradiation time calculation section 74 Drawing control 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 139 Stage Position Detector 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 208,209 Deflector 210 Mirror 330 Membrane Region 332 Peripheral Domain

Claims

1. a beam forming mechanism for forming multiple charged particle beams; a defect correction data creating unit that creates defect correction data defining a dose modulation rate for correcting a dose of a defect beam that is always turned off among the multi-charged particle beams by distributing the dose of the defect beam to one or more other pixels, using a dose distribution that defines a uniform dose at each position of a unit area on a sample surface corresponding to an irradiation area of ​​the entire multi-charged particle beam regardless of a writing pattern; a storage device that stores the defect correction data; a dose calculation unit that calculates, for each drawing pattern, an individual dose at each position on the sample according to the drawing pattern; a dose correction unit that reads out the defect correction data from the storage device for each writing pattern, corrects the individual dose at each position on the sample according to the writing pattern by dose distribution using a value obtained by multiplying the individual dose at each position on the sample by a dose modulation rate defined in the read defect correction data, and obtains a corrected dose; a drawing mechanism that draws the drawing pattern on the sample using the multi-charged particle beam irradiated with the corrected dose; A multi-charged particle beam drawing apparatus comprising:

2. 2. The multi-charged particle beam drawing apparatus according to claim 1, wherein the defect correction data creation unit inputs positional deviation correction data for correcting individual positional deviations of each irradiation position of the multi-charged particle beam, and creates the defect correction data by further using the positional deviation correction data.

3. the writing pattern is written on the sample by multiple writing; 3. The multi-charged particle beam drawing apparatus according to claim 1, wherein the defect correction data creation unit creates the defect correction data so that correction of the dose amount at a position covered by the defect beam, which is performed in one of the multiple passes of the multiple drawing, is performed in another pass.

4. 3. The multi-charged particle beam drawing apparatus according to claim 1, wherein the defect correction data creation unit creates the defect correction data so that correction of the dose amount at the position covered by the defect beam is performed by a peripheral beam that irradiates positions around the position covered by the defect beam.

5. forming a multi-charged particle beam; a step of creating defect correction data defining a dose modulation rate for correcting a dose of a defect beam, which is always turned off among the multi-charged particle beams, at a position assigned to the defect beam by a dose distribution defined by a uniform dose amount at each position of a unit area on a sample surface corresponding to an irradiation area of ​​the entire multi-charged particle beam regardless of a drawing pattern to be drawn, by distributing the dose of the defect beam to one or more other pixels; storing the defect correction data in a storage device; calculating, for each drawing pattern, an individual dose amount at each position on the sample according to the drawing pattern; a step of reading the defect correction data from the storage device for each writing pattern, correcting the individual dose amount at each position on the sample according to the writing pattern by dose distribution using a value obtained by multiplying the individual dose amount at each position on the sample by a dose modulation rate defined in the read defect correction data, and obtaining a corrected dose amount; drawing the pattern on the sample using the multi-charged particle beam irradiated with the corrected dose; A multi-charged particle beam writing method comprising:

Images