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

Abstract

PURPOSE: To provide a drawing device capable of shortening a drawing time in multi-beam drawing.CONSTITUTION: A maximum modulated dose calculation unit 56 configured to calculate, for each of a plurality of first regions obtained by dividing a writing region of a target object to be written, a maximum modulated dose which is maximum-modulated to correct at least one phenomenon of a plurality of phenomena capable of correcting a dimension deviation of a pattern by dose modulation of a charged particle beam; The electron beam drawing apparatus includes a stage speed distribution calculation unit 58 that calculates a stage speed distribution in which a stage speed of a stage on which a sample is placed is defined for each second region having a size equal to or smaller than that of a first region, and a drawing mechanism 150 that has the stage and draws a pattern on the sample using multiple charged particle beams while moving the stage along the stage speed distribution.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a multi-charged particle beam lithography system and a multi-charged particle beam lithography method, and more particularly to a method for varying the stage speed in a multi-beam lithography system. [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] In multi-beam lithography, the dose is controlled by adjusting the irradiation time for each pixel. Furthermore, the irradiation time for each pixel is calculated for the entire region to be lithographed, and the stage speed is determined based on the maximum irradiation time among the calculated values, and the stage is moved at a constant speed. On the other hand, in multi-beam lithography, the irradiation time differs for each shot and each beam. Therefore, in order to shorten the lithography time from the perspective of improving throughput, it is effective to increase the stage speed when lithographing a region with a short irradiation time across the entire multi-beam system, and to decrease the stage speed when lithographing a region with a long irradiation time.

[0005] For example, a technique is being considered in which the maximum irradiation time for each multi-beam shot is calculated and the maximum irradiation times of each shot are summed for each unit area. Then, the stage speed is varied so that the unit area is passed through in the total time (see, for example, Patent Document 1). However, in multi-beam lithography, shot data for the area to be lithographically processed later is generated in parallel with the lithography process. Therefore, data processing, such as calculating the maximum irradiation time for each shot while generating shot data and summing it for each unit area to calculate the stage speed for each unit area, places a heavy load on the computer that executes this processing. For this reason, it is desirable to calculate the stage speed distribution without using the individual irradiation time data for each pixel. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2017-037976 Summary of the Invention [Problem to be solved by the invention]

[0007] One aspect of the present invention provides a writing apparatus and method capable of reducing the writing time in multi-beam writing. [Means for solving the problem]

[0008] A multi-charged particle beam writing apparatus according to one aspect of the present invention comprises: a maximum modulated irradiation dose calculation unit that calculates, for each of a plurality of first regions into which a writing region of a workpiece to be written is divided, a maximum modulated irradiation dose that is maximum modulated to correct at least one phenomenon among a plurality of phenomena that can correct a dimensional deviation of a pattern by modulating the irradiation dose of a charged particle beam; a stage velocity distribution calculation unit that calculates a stage velocity distribution in which the stage velocity of a stage on which a sample is placed is defined for each second region having a size equal to or smaller than the first region, based on the calculated maximum modulated irradiation amount for each first region; a drawing mechanism having a stage and drawing a pattern on the sample using a multi-charged particle beam while moving the stage according to a stage velocity distribution; The present invention is characterized by the following.

[0009] The device further includes a storage device that stores a modulation dose map in which a plurality of modulation doses that can be modulated for each dimensional deviation amount of a pattern caused by at least one phenomenon are defined, It is preferable that the maximum modulated dose is calculated for each first region from within a dose modulation range using multiple modulated doses that can be modulated in response to the dimensional deviation of the pattern in that region due to at least one of the phenomena described above.

[0010] The apparatus further includes a shot data generating unit that generates shot data for each third region that is smaller than the first and second regions, It is preferable that the maximum modulated irradiation amount calculation unit calculates the maximum modulated irradiation amount at a stage before the start of generating shot data.

[0011] At least one of the phenomena is a phenomenon in which a global pattern dimensional deviation occurs, It is preferable to further include a pattern dimension deviation amount calculation unit that calculates the amount of pattern dimension deviation based on the phenomenon that causes a global pattern dimension deviation.

[0012] In addition, the sample is subjected to drawing processing using multiple chip data that define a graphic pattern, It is preferable that the maximum modulated irradiation dose calculation unit calculates the maximum modulated irradiation dose by further using an irradiation dose modulation rate defined for each chip data of the plurality of chip data.

[0013] The drawing mechanism also has a deflector that deflects the multi-charged particle beam, The deflector deflects the beam, allowing tracking control to follow the movement of the stage at each irradiation position of the multi-charged particle beam. It is preferable that the deflection amount in tracking control be changed in accordance with the stage velocity distribution for each tracking cycle.

[0014] A multi-charged particle beam writing method according to one aspect of the present invention includes: calculating a maximum modulated dose for each of a plurality of first regions into which a writing region of a sample to be written is divided, the maximum modulated dose being modulated to correct at least one phenomenon among a plurality of phenomena capable of correcting a dimensional deviation of a pattern by modulating the dose of a charged particle beam; calculating a stage velocity distribution in which the stage velocity of a stage on which a sample is placed is defined for each second region having a size equal to or smaller than that of the first region, based on the calculated maximum modulated irradiation amount for each first region; writing a pattern on a sample using a multi-charged particle beam while moving the stage along the stage velocity profile; The present invention is characterized by the following. [Effects of the Invention]

[0015] According to one aspect of the present invention, the writing time in multi-beam writing can be reduced. [Brief explanation of the drawings]

[0016] [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] FIG. 2 is a flowchart showing an example of main steps of the writing method according to the first embodiment. [Figure 6] FIG. 4 is a diagram showing an example of a global pattern dimension deviation map according to the first embodiment. [Figure 7] FIG. 3 is a diagram showing an example of a modulated dose map according to the first embodiment. [Figure 8]FIG. 2 is a diagram showing an example of a layout of a plurality of chips according to the first embodiment. [Figure 9] FIG. 2 is a diagram showing an example of a block region and a maximum modulated irradiation dose distribution according to the first embodiment. [Figure 10] FIG. 2 is a diagram showing an example of a multi-beam array according to the first embodiment. [Figure 11] FIG. 4 is a diagram showing an example of a maximum modulated irradiation dose distribution for each block region in the first embodiment. [Figure 12] FIG. 4 is a diagram showing an example of a required exposure time distribution for each block region in the first embodiment. [Figure 13] FIG. 10 is a diagram showing an example of maximum stage velocity distribution for each block region according to the first embodiment. [Figure 14] FIG. 2 is a diagram for explaining an example of a multi-beam writing operation according to the first embodiment. [Figure 15] FIG. 3 is a timing chart showing an example of the deflection amount of each deflector in the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] The control computer 110 includes a global pattern density ρ(X) calculation unit 50, a proximity effect density U(X) calculation unit 52, a pattern dimension deviation CD(X) calculation unit 54, a maximum modulated dose Dmax(X) calculation unit 56, a stage velocity distribution calculation unit 58, a modulated dose D(CD,U) calculation unit 60, a shot data generation unit 70, a data processing unit 72, a transfer processing unit 74, and a writing control unit 76. Each of the "units" such as the global pattern density ρ(X) calculation unit 50, the proximity effect density U(X) calculation unit 52, the pattern dimension deviation CD(X) calculation unit 54, the maximum modulated dose Dmax(X) calculation unit 56, the stage velocity distribution calculation unit 58, the modulated dose D(CD,U) calculation unit 60, the shot data generation unit 70, the data processing unit 72, the transfer processing unit 74, and the writing control unit 76 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 "~" unit may use a common processing circuit (the same processing circuit) or may use a different processing circuit (separate processing circuit). Information input / output to / from the global pattern density ρ(X) calculation unit 50, the proximity effect density U(X) calculation unit 52, the pattern dimension deviation amount CD(X) calculation unit 54, the maximum modulated dose Dmax(X) calculation unit 56, the stage speed distribution calculation unit 58, the modulated dose D(CD,U) calculation unit 60, the shot data generation unit 70, the data processing unit 72, the transfer processing unit 74, and the writing control unit 76, as well as information being calculated, are stored in memory 112 each time.

[0023] The drawing operation of the drawing apparatus 100 is controlled by a drawing control unit 76. 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.

[0024] 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.

[0025] 1 shows the configuration necessary for explaining the first embodiment. The drawing device 100 may also include other configurations that are normally required.

[0026] FIG. 2 is a conceptual diagram showing the configuration of a shaping aperture array substrate in the first embodiment. In FIG. 2, holes (openings) 22 are formed in a matrix of p columns (y direction) by q columns (x direction) (p, q≧2) at a predetermined arrangement pitch in the shaping aperture array substrate 203. The example in FIG. 2 shows a case where, for example, 512×512 columns of holes 22 are formed in the vertical and horizontal directions (x, 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, it 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.

[0027] 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.

[0028] 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.

[0029] 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).

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 4 shows the case where the stage is moved once for the writing process of each stripe region, but this is not limiting. Multiple writing may also be performed by moving the stage multiple times over the same position. In this case, it is preferable to perform multiple writing while shifting the stage in the y direction by an amount that is 1 / n of the width of the stripe region, for example.

[0036] As described above, in order to shorten the writing time from the viewpoint of improving throughput, it is effective to increase the stage speed when writing an area where the irradiation time is short across the multi-beams, and to decrease the stage speed when writing an area where the irradiation time is long.

[0037] However, in multi-beam lithography, shot data for the area to be lithographically processed later is generated in parallel with the lithography process. Therefore, data processing such as calculating the maximum irradiation time for each shot while generating shot data, adding up the total for each unit area, and calculating the stage velocity for each unit area places a heavy load on the computer that executes this processing. Therefore, it is desirable to calculate the stage velocity distribution without using the individual irradiation time data for each pixel.

[0038] Therefore, in the first embodiment, attention is focused on multiple phenomena that can correct pattern dimensional deviations by modulating the dose of an electron beam. Examples of multiple phenomena that can correct pattern dimensional deviations by modulating the dose include the fogging effect, the loading effect, and the proximity effect. Among these phenomena, the first embodiment focuses on the fogging effect and / or the loading effect, which cause global pattern dimensional deviations. Therefore, in the first embodiment, the maximum value of the modulation amount for correcting at least one of the multiple phenomena that can correct pattern dimensional deviations by modulating the dose of an electron beam is predicted for each predetermined region. Then, the stage velocity distribution corresponding to the predicted maximum modulation dose is calculated. The specific operation is described below.

[0039] Fig. 5 is a flowchart showing an example of main steps of the writing method according to Embodiment 1. In Fig. 5, the writing method according to Embodiment 1 carries out a series of steps including a global pattern density ρ(X) calculation step (S102), a proximity effect density U(X) calculation step (S104), a pattern dimension deviation amount CD(X) calculation step (S106), a maximum modulated dose Dmax(X) calculation step (S108), a stage speed distribution calculation step (S110), a modulated dose D(CD,U) calculation step (S120), a shot data generation step (S130), a data processing step (S132), and a writing step (S140).

[0040] In the global pattern density ρ(X) calculation step (S102), the ρ(X) calculation unit 50 divides each stripe region 32 (an example of a writing region) of the sample 101 to be written into multiple global meshes (first regions). The range of influence of phenomena that cause global pattern dimensional deviations, such as the fogging effect and the loading effect, is approximately 1 to 10 mm. The global mesh is set to a size sufficiently smaller than the range of influence. For example, it is preferable to set it to approximately 1 / 10 of the above-mentioned range of influence. The size of the global mesh is preferably set to approximately 0.1 to 1 mm. Then, the ρ(X) calculation unit 50 reads writing data for the target stripe region 32 from the storage device 140 and calculates, for each global mesh, a global pattern density ρ(X) that indicates the pattern area ratio within that mesh. X indicates the index of the global mesh.

[0041] In the proximity effect density U(X) calculation step (S104), the U(X) calculation unit 52 calculates the proximity effect density U(X) for each stripe region 32. The proximity effect density U(X) can be defined by the following formula (1) using the global pattern density ρ(X) and a distribution function g(x). The lowercase letter x indicates a vector indicating a position. The unit of the vector is a value sufficiently small compared to the global mesh size. The distribution function g(x, y) may be, for example, a Gaussian function.

[0042]

number

[0043] In the pattern dimension deviation amount CD(X) calculation step (S106), the CD(X) calculation unit 54 calculates the pattern dimension deviation amount CD(X) for each stripe region 32. The CD(X) calculation unit 54 calculates the pattern dimension deviation amount CD(X) based on a phenomenon that causes a global pattern dimension deviation. The pattern dimension deviation amount CD(X) is preferably defined as the sum of the value of the global position-dependent pattern dimension deviation amount map CDmap(X) and the area-dependent value. The pattern dimension deviation amount CD(X) can be defined by the following equation (2) using CDmap(X), an influence coefficient γ of the phenomenon that causes a global pattern dimension deviation, the global pattern density ρ(X), and the distribution function g(x).

[0044]

number

[0045] 6 is a diagram showing an example of a global pattern dimension deviation map according to the first embodiment. The global pattern dimension deviation map 40 shows, in a map, an error that does not match only with the integral term of the area-dependent component of the second term in equation (2). For example, as shown in FIG. 6, the deviation amount of the pattern dimension at each position is shown. If the allowable accuracy of the pattern dimension deviation CD(X) can be obtained by the integral term of the area-dependent component of equation (2), the global pattern dimension deviation map 40 may be omitted.

[0046] In the maximum modulated dose Dmax(X) calculation step (S108), the Dmax(X) calculation unit 56 calculates, for each global mesh (first region), the maximum modulated dose Dmax(X) that is maximally modulated to correct at least one of a plurality of phenomena that can correct pattern dimensional deviations by modulating the dose of the electron beam.

[0047] FIG. 7 is a diagram showing an example of a modulated dose map in the first embodiment. In FIG. 7, the vertical axis of the modulated dose map 42 represents the proximity effect density U(X), and the horizontal axis represents the pattern dimension deviation CD(X). In the modulated dose map 42, for each pattern dimension deviation CD(X) caused by at least one phenomenon that causes a global pattern dimension deviation, multiple modulated doses D(CD,U) that correct the pattern dimension deviation CD(X) are defined. In other words, in the modulated dose map 42, multiple modulated doses that can be modulated for each pattern dimension deviation caused by at least one phenomenon among multiple phenomena that cause pattern dimension deviation that can be corrected by dose modulation are defined. Specifically, the modulated dose D(CD,U) is defined for each combination of the pattern dimension deviation CD(X) and the proximity effect density U(X). The modulated dose D(CD,U) is calculated by multiplying the reference dose D 100 , backscattering coefficient η, proximity effect density U(X), pattern dimension deviation CD(X), and tolerance DL(U), can be defined by, for example, the following equation (3).

[0048]

number

[0049] The modulated dose map 42 shown in FIG. 100 The modulated dose itself is calculated by multiplying the reference dose D 100 The modulation factor may be defined by a term excluding the above. The tolerance DL(U) depends on the proximity effect density U(X), and is defined, for example, by the slope (proportional coefficient) of a graph in which the vertical axis indicates the dimension CD of a pattern drawn with an electron beam and the horizontal axis indicates the logarithm (log) of the electron beam dose. However, this is not limited to this. The tolerance DL(U) may be defined as a parameter (coefficient) that indicates the relationship between the pattern dimension CD and the dose D(U). The modulation dose map 42 is stored (memorized) in the storage device 144.

[0050] The Dmax(X) calculation unit 56 calculates, for each global mesh (first region), a modulated irradiation dose Dmax(X) from within an irradiation dose modulation range based on a plurality of modulated irradiation doses that can be modulated in response to a pattern dimension deviation within the global mesh. Specifically, the Dmax(X) calculation unit 56 calculates, for each global mesh, a maximum modulated irradiation dose Dmax(X) that is the maximum from among the modulated irradiation doses D(CD,U) for each proximity effect density U(X) that can correct the calculated pattern dimension deviation CD(X). The irradiation dose is maximum when the proximity effect density U(X)=0. Therefore, for each global mesh (first region), the modulated irradiation dose D(CD,U) corresponding to the combination of the calculated pattern dimension deviation CD(X) and U(X)=0 may be calculated as the maximum modulated irradiation dose Dmax(X) (=D(CD,0)).

[0051] Here, if there is no location within the global mesh where U=0, the actual maximum modulated dose within that global mesh will be smaller than D(CD,0). Therefore, to further improve accuracy, U(X) is calculated for each sub-mesh that is smaller than the global mesh. For example, it is preferable to set the size of the sub-mesh to 1 μm to 5 μm, which is smaller than the proximity effect distribution radius of 10 μm but not too fine. Then, it is also preferable to find the minimum value Umin(X) of U(X) for each sub-mesh and calculate D(CD,Umin) corresponding to this minimum value Umin(X) of U(X) as the maximum modulated dose Dmax(X).

[0052] FIG. 8 is a diagram showing an example of a layout of multiple chips according to the first embodiment. The example in FIG. 8 illustrates a case where chip patterns of multiple chips are arranged in the writing area 30 of the sample 101. Writing processing may be performed on the sample 101 using multiple chip data defining graphic patterns. The example in FIG. 8 illustrates a case where chip 1 is arranged in the center of the writing area 30 and chip 2 is arranged in the peripheral area. In electron beam writing, it is possible to consider dose modulation other than dose modulation for correcting global pattern dimension deviation phenomena such as fogging and loading effects, and proximity effects. For example, a dose modulation factor k1 may be set for each chip. In such a case, the Dmax(X) calculation unit 56 calculates the maximum modulated dose Dmax(X) by further using the dose modulation factor k1 defined for each chip data of the multiple chip data. The maximum modulated dose Dmax can be defined by the following equation (4):

[0053]

number

[0054] Furthermore, when a dose modulation rate k2 of another correction function is set, the maximum modulated dose Dmax may be defined by the following equation (5).

[0055]

number

[0056] Furthermore, the multi-beam 20 may have a current density distribution in which the current density is not uniform. To correct the difference in current density between such beams, dose modulation is required. In such cases, Dmax(X) is calculated by multiplying the ratio obtained by dividing the maximum value of the current density distribution by the minimum value by Dmax(X). For example, the ratio can be calculated by dividing the current density of the central beam of the multi-beam 20 by the current density of the edge beam.

[0057] As a stage velocity distribution calculation step (S110), the stage velocity distribution calculation unit 58 calculates a stage velocity distribution in which the stage velocity v of the XY stage 105 is defined for each block region (second region) whose size is smaller than the global mesh, based on the calculated maximum modulated irradiation dose Dmax(X) for each global mesh.

[0058] FIG. 9 is a diagram showing an example of a block region and a maximum modulated dose distribution in the first embodiment. As shown in FIG. 9, a stripe region 32 is divided to set a plurality of block regions 48. The block regions 48 may be regions of a size equal to or smaller than the global mesh 46. For example, if the stage velocity for each global mesh 46 varies too much between adjacent meshes, the mesh size can be reduced to reduce the velocity variation between the meshes. The example in FIG. 9 shows an example of the distribution of the maximum modulated dose Dmax for each block region 48. Next, an example of how to calculate the stage velocity will be described.

[0059] FIG. 10 is a diagram showing an example of a multibeam array according to the first embodiment. The example of FIG. 10 shows, for example, an 8×8 multibeam array 20. The beam array size L in the x direction is defined by the inter-beam pitch in the x direction multiplied by the number of beams in the x direction. The beam array size L in the y direction is defined by the inter-beam pitch in the y direction multiplied by the number of beams in the y direction. The area surrounded by the beam array size L in the x direction × the beam array size L in the y direction is the multibeam irradiation area 34. In the example of FIG. 9, the inter-beam pitch is, for example, a distance of 4 pixels 36. Therefore, the sub-irradiation area 29 of each beam 28 constituting the multibeam 20 is the area surrounded by the inter-beam pitch in the x direction and the inter-beam pitch in the y direction. In the example of FIG. 10, the sub-irradiation area 29 is composed of 4×4 pixels.

[0060] Here, the shot cycle T of the multi-beam 20 is defined as the sum (T=t+Δ) of the preset maximum irradiation time t and the deflection settling time Δ for the DAC amplifier unit 132 for the sub-deflector 209. The maximum irradiation time t is defined as the value (t=Dmax / J) obtained by dividing the maximum irradiation amount Dmax of all the irradiation amounts for all pixels by the current density J.

[0061] The XY stage 105 must move by the beam array size L within the time given by the product KMT of the ratio K obtained by dividing the number of pixels in the beam array by the number of beams, the multiplicity M when performing multiple drawing, and the shot cycle T. Therefore, the maximum stage speed v is defined by the following equation (6).

[0062]

number

[0063] The stage velocity distribution calculation unit 58 calculates the maximum stage velocity v of the XY stage 105 for each block region 48 using equation (6).

[0064] FIG. 11 is a diagram showing an example of the maximum modulated irradiation dose distribution for each block region according to the first embodiment. FIG. 12 is a diagram showing an example of a required exposure time distribution for each block region according to the first embodiment. FIG. 13 is a diagram showing an example of the maximum stage velocity distribution for each block region in embodiment 1. The maximum modulated dose distribution in FIG. 11 is the same as the maximum modulated dose distribution shown in FIG. 9. The required exposure time (maximum irradiation time t) for each block region 48 can be calculated by dividing the maximum modulated dose Dmax for each block region 48 shown in FIG. 11 by the current density J. This allows the stage velocity distribution calculation unit 58 to calculate the required exposure time distribution shown in FIG. 12. Next, the required exposure time (maximum irradiation time t) for each block region 48 shown in FIG. 11 can be substituted into equation (6) to calculate the maximum stage velocity v for each block region 48. This allows the stage velocity distribution calculation unit 58 to calculate the maximum stage velocity distribution shown in FIG. 13.

[0065] Next, the stage velocity distribution calculation unit 58 calculates the stage velocity distribution so that the maximum stage velocity v of each block region 48 is reached at some position within that block region 48. It is preferable to set the stage velocity as fast as possible without exceeding the maximum stage velocity v of each block region 48. In the example of FIG. 13 , if the maximum stage velocity v of an adjacent block region 48 along the traveling direction is greater, the maximum stage velocity v of that block region is set at the final position of that block region. If the maximum stage velocity v of an adjacent block region 48 along the traveling direction is smaller, the maximum stage velocity v of the adjacent block region is set at the final position of that block region. By connecting these multiple points, it is possible to calculate a stage velocity distribution (stage velocity profile) in which the velocity changes gradually. It is also preferable to calculate a stage velocity distribution using a gentle curve by approximating these multiple points with a curve.

[0066] In the modulated dose D(CD,U) calculation step (S120), the D(CD,U) calculation unit 60 refers to the modulated dose map and calculates the modulated dose D(CD,U) for each global mesh. Here, the modulated dose D(CD,U) corresponding to the proximity effect density U(X) of the global mesh is calculated.

[0067] The above-described processes are performed as pre-processing before the writing process starts. In other words, the Dmax(X) calculation unit 56 calculates Dmax(X) before the generation of shot data starts. Furthermore, the stage velocity distribution calculation unit 58 calculates the stage velocity distribution (stage velocity profile) before the generation of shot data starts. The stage velocity distribution data is stored in the storage device 144.

[0068] In the shot data generation step (S130), the shot data generation unit 70 generates shot data for each pixel 36 (third region) that is smaller than the global mesh 46 and the block region 48. Specifically, the operation is as follows. First, the shot data generation unit 70 reads out drawing data from the storage device 140, and calculates, for each pixel 36, the pattern area density ρ′ within that pixel 36. This process is executed, for example, for each stripe region 32.

[0069] Next, the shot data generation unit 70 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 of 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 shot data generation unit 70 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 placed in that proximity mesh region.

[0070] Next, the shot data generation unit 70 calculates a proximity effect correction exposure coefficient Dp(x) (corrected exposure dose) for correcting the proximity effect for each proximity mesh region. The unknown proximity effect correction exposure coefficient Dp(x) can be defined by a threshold model for proximity effect correction similar to that of the conventional method, using the backscattering coefficient η, the pattern area density ρ″, and the distribution function g(x).

[0071] Next, the shot data generation unit 70 calculates, for each pixel 36, the incident irradiation dose D(x) (dose) to be applied to that pixel 36. The incident irradiation dose D(x) may be calculated, for example, by multiplying the modulated irradiation dose D(CD,U) described above by the proximity effect correction irradiation coefficient Dp and the pattern area density ρ'. The reference irradiation dose Dbase may be defined, for example, as the irradiation dose threshold Dth / (1 / 2 + η) of the threshold model. As a result, the incident irradiation dose D(x) for each pixel 36, corrected for the proximity effect and global pattern dimensional deviation based on the layout of the multiple graphic patterns defined in the writing data, can be obtained.

[0072] Next, the shot data generation unit 70 calculates the irradiation time for each pixel 36. The irradiation time for each pixel 36 can be calculated by dividing the incident irradiation amount D(x) of the pixel by the current density J.

[0073] In the data processing step (S132), the data processing unit 72 groups the obtained irradiation time data for each pixel 36 into corresponding shot sets, arranges them in shot order, and stores them 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 writing step (S140), under the control of the writing control unit 76, the writing mechanism 150 writes a pattern on the sample 101 using the multi-beams 20 while moving the XY stage 105 according to the stage velocity distribution. In multi-beam writing, while writing processing is being performed, shot data for the region to be written later is generated in parallel. For example, while writing is being performed on the k-th stripe region 32, shot data for the k+2-th stripe region 32 is generated in parallel. By repeating this operation, writing is performed on all stripe regions 32.

[0075] Fig. 14 is a diagram for explaining an example of a multi-beam writing operation in the first embodiment. The example of Fig. 14 shows a case where writing is performed with four different beams in each sub-irradiation area 29, which includes one beam irradiation position of each of the multi-beams 20 and is surrounded by the beam pitch. The example of Fig. 14 also shows a writing operation in which the XY stage 105 moves continuously at a speed corresponding to a distance of two beam pitches while writing 1 / 4 of the area in each sub-irradiation area 29 (one for the number of beams used for irradiation). The example of Fig. 14 shows a case where each sub-irradiation area 29 is composed of, for example, 4 x 4 pixels.

[0076] In the drawing operation shown in the example of FIG. 14 , for example, while the XY stage 105 moves a distance of two beam pitches in the x direction, the sub-deflector 209 sequentially shifts the irradiation position (pixel 36), and four shots of the multi-beam 20 are fired in a shot cycle T to draw (expose) four different pixels 36 in the same sub-irradiation area 29. While drawing (exposing) these four pixels 36, the main deflector 208 deflects the entire multi-beam 20 collectively so that the relative position of the irradiation area 34 to the sample 101 does not shift due to the movement of the XY stage 105, thereby causing the irradiation area 34 to follow the movement of the XY stage 105. In other words, tracking control is performed. When one tracking cycle is completed, tracking is reset and the system returns to the previous tracking start position. Note that since the drawing of the first pixel row from the left in each sub-irradiation area 29 has been completed, after a tracking reset, in the next tracking cycle, the sub-deflector 209 first deflects the beam to align (shift) the drawing position so that the beam draws an undrawn pixel row, for example, the second pixel row from the left, in each sub-irradiation area 29. By repeating this operation during drawing of the stripe area 32, the positions of the irradiation areas 34 (34a to 34o) of the multi-beam 20 are sequentially moved, as shown in the lower diagram of FIG.

[0077] FIG. 15 is a timing chart showing an example of the deflection amount of each deflector in the first embodiment. In FIG. 15, the x-direction deflection (mainX) by the main deflector 208 is tracking deflection for performing tracking control in accordance with the movement of the XY stage 105. After four pixel shots, the deflection amount of mainX is also reset by a tracking reset. The y-direction deflection (mainY) by the main deflector 208 is not necessary and is therefore not performed. During one tracking control, the y-direction deflection (subY) by the sub deflector 209 moves the multibeam 20 in the y direction by one pixel for each shot. Furthermore, the x-direction deflection (subX) by the sub deflector 209 is deflected at each tracking reset so as to move the multibeam 20 to an adjacent pixel row that has not yet been drawn, other than the pixel row that has already been irradiated. In the examples of FIGS. 14 and 15, the irradiation of all pixels of each sub-irradiation area 29 within the irradiation area 34 of the multibeam 34 is completed through four tracking cycles.

[0078] In this way, tracking control is performed by deflecting the beam by the main deflector 208, causing each irradiation position of the multi-beam 20 to follow the movement of the XY stage 105. The tracking deflection sensitivity must be corrected according to changes in the stage speed at that position. For example, if the stage speed changes by 5 mm / s while the stage moves a distance equivalent to 2000 shots, a speed change of, for example, 0.0025 mm / s will occur per shot cycle. In this case, a positional deviation of 0.0025 mm / s × irradiation time t will occur between the start and end positions of one shot. Therefore, the deflection control circuit 130 changes the deflection amount in tracking control by the main deflector 208 according to the stage speed distribution.

[0079] Alternatively, the deflection control circuit 130 changes the deflection amount in tracking control by the main deflector 208 in accordance with the stage velocity distribution for each tracking cycle. In the example of Fig. 15, as shown by mainX of the main deflector 208, the deflection amount increases as the stage velocity increases over four tracking cycles. In this case, a tracking position shift occurs due to a change in velocity during tracking, but the tracking position shift can be adjusted by the x-direction deflection amount of the sub deflector 209. In the example of Fig. 15, because the amount of change in the tracking position shift is small, the change in the deflection amount corresponding to the tracking position shift by the sub deflector 209 is omitted from the time chart of subX.

[0080] As described above, according to the first embodiment, the stage velocity distribution can be calculated without being based on the individual irradiation time data for each pixel. Therefore, the stage velocity can be calculated at a stage before the shot data is generated. Therefore, when performing parallel processing of the writing process and the shot data generation process, it is possible to avoid processing that places an excessive load on the computer, such as calculating the stage velocity in parallel. Therefore, according to the first embodiment, a variable stage velocity distribution can be obtained. As a result, according to the first embodiment, the writing time in multi-beam writing can be shortened.

[0081] The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In the embodiments, multi-beam writing has been described, but the present invention is applicable to a single-beam irradiation device, including a laser, as long as it is a device that performs raster beam irradiation, without being limited to a charged particle beam.

[0082] 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.

[0083] 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]

[0084] 20 Multibeam 22 holes 23 electrodes 24 control electrode 25 Passing hole 26 Counter electrode 29 Sub-irradiation area 32 stripe area 34 Irradiation area 36 pixels 41 Control circuit 50 Global pattern density calculation unit 52 Proximity effect density calculation section 54 Pattern dimension deviation calculation unit 56 Maximum modulation dose calculation unit 58 Stage velocity distribution calculation unit 60 Modulated irradiation amount calculation unit 70 Shot data generation unit 72 Data Processing Department 74 Transfer Processing Unit 76 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 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 maximum modulated irradiation dose calculation unit that calculates, for each of a plurality of first regions into which a writing region of a sample to be written is divided, a maximum modulated irradiation dose that is maximum modulated to correct at least one phenomenon among a plurality of phenomena that can correct a dimensional deviation of a pattern by modulating the irradiation dose of a charged particle beam; a stage velocity distribution calculation unit that calculates a stage velocity distribution in which a stage velocity of a stage on which the sample is placed is defined for each second region having a size equal to or smaller than the first region, based on the calculated maximum modulated irradiation amount for each first region; a drawing mechanism having the stage and drawing a pattern on the sample using a multi-charged particle beam while moving the stage along the stage velocity distribution; A multi-charged particle beam drawing apparatus comprising:

2. a storage device that stores a modulation dose map that defines a plurality of modulation doses that can be modulated for each dimensional deviation amount of the pattern caused by the at least one phenomenon; 2. The multi-charged particle beam drawing apparatus according to claim 1, wherein the maximum modulated dose is calculated for each of the first regions from within a dose modulation range based on the plurality of modulated doses that can be modulated in response to a dimensional deviation of a pattern in the region caused by the at least one phenomenon.

3. a shot data generating unit that generates shot data for each third region that is smaller than the first and second regions; 3. The multi-charged particle beam drawing apparatus according to claim 1, wherein the maximum modulated dose calculation unit calculates the maximum modulated dose at a stage before the generation of the shot data starts.

4. the at least one phenomenon is a phenomenon in which a global pattern dimensional deviation occurs, 4. The multi-charged particle beam drawing apparatus according to claim 1, further comprising a pattern dimension deviation amount calculation unit that calculates a pattern dimension deviation amount based on the phenomenon that causes the global pattern dimension deviation.

5. The sample is subjected to a drawing process using a plurality of chip data that define a graphic pattern, The multi-charged particle beam drawing apparatus according to any one of claims 1 to 4, characterized in that the maximum modulated irradiation dose calculation unit calculates the maximum modulated irradiation dose by further using an irradiation dose modulation rate defined for each chip data of the plurality of chip data.

6. the drawing mechanism has a deflector that deflects the multi-charged particle beam; a tracking control is performed by deflecting the beam by the deflector, so that each irradiation position of the multi-charged particle beam follows the movement of the stage; 6. The multi-charged particle beam drawing apparatus according to claim 1, wherein the deflection amount in the tracking control changes in accordance with the stage velocity distribution for each tracking cycle.

7. calculating a maximum modulated dose for each of a plurality of first regions into which a writing region of a sample to be written is divided, the maximum modulated dose being modulated to correct at least one phenomenon among a plurality of phenomena capable of correcting a dimensional deviation of a pattern by modulating the dose of a charged particle beam; calculating a stage velocity distribution in which a stage velocity of a stage on which the sample is placed is defined for each second region having a size equal to or smaller than the first region, based on the calculated maximum modulated irradiation amount for each first region; writing a pattern on the sample using a multi-charged particle beam while moving the stage along the stage velocity profile; A multi-charged particle beam writing method comprising:

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