Mark position measurement method, multi charged particle beam drawing method, and multi charged particle beam drawing apparatus

Abstract

To accurately measure a mark position with a multi-beam even when a distribution of current amounts exists within a beam array plane.SOLUTION: A mark position measurement method according to an embodiment forms a multi-beam in which charged particle beams are arranged at a predetermined pitch, sequentially switches an on-beam region in which beams in a partial region of the multi-beam are turned on, pseudo-scans a mark that is provided at a predetermined position and has a width larger than the predetermined pitch by shifting irradiation positions of the charged particle beams, detects a reflected charged particle signal from the mark, and measures a position of the mark on the basis of the detected reflected charged particle signal. In switching the on-beam region, a unit-time average of beam current on a substrate on which the mark is formed is maintained constant.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a mark position measuring method, a multi-charged particle beam writing method, and a multi-charged particle beam writing apparatus. [Background technology]

[0002] As LSIs become more highly integrated, the circuit line width required for semiconductor devices is becoming finer every year. To form the desired circuit pattern on a semiconductor device, a method is adopted in which a high-precision master pattern formed on quartz is reduced and transferred onto a wafer using a reduction projection exposure system. To create the high-precision master pattern, a technique known as electron beam lithography is used, in which a resist is exposed to light using an electron beam writing system to form the pattern.

[0003] A multi-beam lithography system can irradiate multiple beams at once compared to lithography using a single electron beam, significantly improving throughput. In a multi-beam lithography system using a blanking aperture array substrate (blanking plate), for example, an electron beam emitted from a single electron gun passes through a shaping aperture array with multiple apertures to form multiple beams (multiple electron beams). The multiple beams pass through corresponding blankers (electrode pairs) in the blanking aperture array. The blanker has electrode pairs for individually deflecting the beams, with apertures formed between the electrode pairs for beam passage. Blanking deflection of the passing electron beams is achieved by fixing one electrode of the blanker at ground potential and switching the other electrode between ground potential and another potential. Electron beams deflected by the blanker are shielded and turned off, while undeflected electron beams are irradiated onto the substrate on the stage as on beams.

[0004] In multi-beam writing, the writing operation is temporarily suspended at certain writing units, the multi-beams are shifted while being irradiated (scanned) onto a mark on the stage, the reflected electron signal from the mark is detected, the mark position is calculated from the detection results, the amount of beam drift (the amount of shift of the entire beam) is found, and drift correction is performed.

[0005] Phase shifting is one method for improving resolution in photolithography. Phase shift masks require two layers of patterns: a light-shielding pattern layer and a halftone pattern layer, so alignment accuracy is important when overlaying these patterns. For example, a cross mark pattern for alignment is created when forming the first layer pattern. The cross mark is then scanned with multiple beams to detect the reflected electron signal, and the position of the cross mark is calculated from the detection results, and the drawing position of the second layer pattern is adjusted.

[0006] In this way, in multi-beam writing, marks placed on a stage or substrate are scanned with multiple beams to measure their positions. When measuring mark positions with multiple beams, because the current density of each beam is low, multiple beams in a specific area are turned on and treated as a single beam to scan the mark. In this case, as shown in Figure 15, it was necessary to scan a range larger than the sum of the size of the beam area BG1 and the width W of the mark M. Therefore, when the deflector deflects the multiple beams to scan, deflection distortion occurs, and the beams approach the deflector, causing drift, making it difficult to accurately measure the mark position.

[0007] Patent Document 1 discloses a method for measuring the position of a mark by scanning the mark while shifting the beam irradiation position by sequentially switching on-beam areas in which beams in some areas of the multi-beam are turned on. This method eliminates the need to deflect the multi-beam, thereby preventing deflection distortion.

[0008] However, when there is a distribution of current within the multi-beam array plane, in other words, when there is variation in the current density for each beam, it is difficult to accurately measure the mark position. For example, when a beam with a high current density is irradiated onto an area other than the mark and a beam with a low current density is irradiated onto the mark area, it becomes difficult to distinguish the peak caused by the mark from the detection results of the backscattered electron signal, making it difficult to measure the mark position. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2021-132149 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-140844 [Patent Document 3] Japanese Patent Application Laid-Open No. 2004-134503 [Patent Document 4] Japanese Patent Application Publication No. 9-330869 Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present invention is to provide a mark position measurement method, a multi-charged particle beam writing method, and a multi-charged particle beam writing apparatus that can accurately measure mark positions with multiple beams even when there is a distribution of current amounts within the beam array surface. [Means for solving the problem]

[0011] A mark position measurement method according to one aspect of the present invention forms a multi-beam in which charged particle beams are arranged at a predetermined pitch, sequentially switches on-beam areas in which the beams of some areas of the multi-beams are turned on, and shifts the irradiation position of the charged particle beam to pseudo-scan a mark that is provided at a predetermined position and has a width wider than the predetermined pitch, detects a reflected charged particle signal from the mark, and measures the position of the mark based on the detected reflected charged particle signal, and when the on-beam area is switched, the unit time average of the beam current on the substrate on which the mark is formed is kept constant.

[0012] A multi-charged particle beam writing method according to one aspect of the present invention writes a pattern by adjusting the irradiation positions of the multi-beams based on the positions of the marks measured by the mark position measuring method according to one aspect of the present invention.

[0013] A multi-charged particle beam writing apparatus according to one aspect of the present invention comprises an aperture array substrate that forms multiple beams in which charged particle beams are arranged at a predetermined pitch; a stage on which a pattern writing target is placed; a mark formed on a mark substrate on the stage or on the pattern writing target and having a width wider than the predetermined pitch; a control unit that sequentially switches on-beam areas in which beams in a portion of the multiple beams are turned on and shifts the irradiation position of the charged particle beam to pseudo-scan the mark; a detector that detects reflected charged particle signals from the mark; and a mark position calculation unit that calculates the position of the mark based on the detected reflected charged particle signal, wherein the control unit keeps the unit time average of the beam current in the mark substrate or the pattern writing target constant when the on-beam areas are switched on. [Effects of the Invention]

[0014] According to the present invention, even if there is a distribution of the amount of current within the beam array plane, the mark position can be measured with high precision using multiple beams. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram of a multi-charged particle beam writing apparatus according to an embodiment of the present invention; [Figure 2] FIG. 2 is a plan view of a shaped aperture array substrate. [Figure 3] 10(a) to 10(d) are diagrams illustrating switch scanning. [Figure 4] 10(a) to 10(c) are diagrams illustrating a switch scan. [Figure 5] 10 is a graph showing an example of a detection result of a backscattered electron signal. [Figure 6] 10 is a graph showing an example of a detection result of a backscattered electron signal. [Figure 7] FIG. 10 is a diagram showing an on-beam region used for switch scanning. [Figure 8] 10 is a graph showing an example of a detection result of a beam current in an on-beam region used for switch scanning. [Figure 9] 10 is a flowchart illustrating a drawing method according to the embodiment. [Figure 10] 10(a) to 10(g) are diagrams showing beams that are turned on during switch scanning. [Figure 11] 10 is a graph showing an example of a detection result of a backscattered electron signal. [Figure 12] 10 is a graph showing an example of a detection result of a backscattered electron signal. [Figure 13] 10 is a graph showing an example of a detection result of a backscattered electron signal. [Figure 14] 10 is a flowchart illustrating a drawing method according to another embodiment. [Figure 15] FIG. 2 is a diagram illustrating deflection scanning. [Figure 16] FIG. 1 is a schematic diagram illustrating the configuration of an inspection device. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the embodiment, a configuration using an electron beam as an example of a charged particle beam will be described. However, the charged particle beam is not limited to an electron beam, and an ion beam or the like may also be used.

[0017] Fig. 1 is a conceptual diagram showing the configuration of a lithography apparatus according to this embodiment. In Fig. 1, the lithography apparatus includes a lithography unit 1 and a control unit 100. The lithography apparatus is an example of a multi-charged particle beam lithography apparatus. The lithography unit 1 includes an electron optical column 2 and a lithography chamber 20. Inside the electron optical column 2, an electron source 4, an illumination lens 6, a shaping aperture array substrate 8, a blanking aperture array substrate 10, a reduction lens 12, a limiting aperture member 14, an objective lens 15, a deflector 17, etc. are arranged.

[0018] An XY stage 22 and a detector 26 are arranged in the patterning chamber 20. A substrate 70, which is the target to be irradiated (target to be patterned), is arranged on the XY stage 22. The height of the substrate 70 can be adjusted by a Z stage (not shown). The substrate 70 is, for example, a mask blank or a semiconductor substrate (silicon wafer).

[0019] A mirror 24 for measuring the position of the XY stage 22 is disposed on the XY stage 22. Also provided on the XY stage 22 is a mark substrate 28 on which a mark M (see FIG. 4) for beam calibration is formed. The mark M is made of metal and has, for example, a cross shape so that its position can be easily detected by scanning it with an electron beam. The detector 26 detects a reflected electron signal from the mark M when the cross of the mark M is scanned with the electron beam.

[0020] A current detector 50 is provided on the XY stage 22 at a position different from the position where the substrate 70 is placed. A Faraday cup, for example, can be used as the current detector 50. The detection result of the current detector 50 is sent to the control computer 110.

[0021] The control unit 100 has a control computer 110, a deflection control circuit 130, a digital-to-analog conversion (DAC) amplifier 131, a detection amplifier 134, a stage position detector 135, and memory devices 140 and 142. The memory devices 140 and 142 are magnetic disk devices or the like. Writing data is input from the outside and stored in the memory device 140. Current amount information, which will be described later, is stored in the memory device 142.

[0022] The deflection control circuit 130 is connected to a DAC amplifier 131. The DAC amplifier 131 is connected to the deflector 17.

[0023] The control computer 110 includes a writing data processing unit 111, a writing control unit 112, a mark position calculation unit 113, a correction unit 114, and a current distribution calculation unit 115. The functions of each unit of the control computer 110 may be realized by hardware or software. When configured by software, a program that realizes at least some of the functions of the control computer 110 may be stored in a recording medium and read and executed by a computer including a CPU or the like. The recording medium is not limited to removable recording media such as magnetic disks and optical disks, but may also be fixed recording media such as hard disk drives and memories.

[0024] Fig. 2 is a conceptual diagram showing the configuration of the shaping aperture array substrate 8. As shown in Fig. 2, the shaping aperture array substrate 8 has m vertical (y direction) columns x n horizontal (x direction) columns (m, n ≥ 2) openings 80 formed in a matrix at a predetermined arrangement pitch.

[0025] Electron beam 3 emitted from electron source 4 is illuminated almost perpendicularly by illumination lens 6 onto shaping aperture array substrate 8. Electron beam 3 illuminates an area including openings 80 in shaping aperture array substrate 8. Portions of electron beam 3 pass through each of these multiple openings 80, forming multi-beams 30 with a predetermined pitch and size, as shown in FIG. 1. Note that multi-beams may also be formed using a photocathode.

[0026] In the blanking aperture array substrate 10, through-holes (openings) through which each beam (individual beam) of the multi-beam 30 passes are formed at positions corresponding to each opening 80 of the shaping aperture array substrate 8 shown in Fig. 2. In the vicinity of each through-hole, a blanking deflection electrode (blanker: blanking deflector) for deflecting the individual beam is arranged.

[0027] Each individual beam passing through each aperture is deflected independently by a voltage applied from a blanker. Blanking control is performed by this deflection. In this way, the blankers perform blanking deflection of the corresponding individual beams among the multi-beams that have passed through the multiple openings 80 of the shaping aperture array substrate 8.

[0028] The multiple beams 30 that have passed through the blanking aperture array substrate 10 have their individual beam sizes and array pitches reduced by the reduction lens 12, and proceed toward the opening formed in the center of the limiting aperture member 14. The individual beams that have been deflected by the blanker of the blanking aperture array substrate 10 have their trajectories displaced, and are no longer positioned at the opening in the center of the limiting aperture member 14, and are blocked by the limiting aperture member 14. On the other hand, the individual beams that have not been deflected by the blanker of the blanking aperture array substrate 10 pass through the opening in the center of the limiting aperture member 14.

[0029] The multi-beams 30 that have passed through the limiting aperture member 14 are focused by the objective lens 15, and become a pattern image with the desired reduction ratio on the substrate 70. An electrostatic lens can be used as the objective lens 15. The deflector 17 deflects all of the multi-beams that have passed through the limiting aperture member 14 in the same direction, and irradiates them onto the drawing position (irradiation position) on the substrate 70.

[0030] When the XY stage 22 is moving continuously, the deflector 17 performs tracking control so that the beam drawing position (irradiation position) follows the movement of the XY stage 22. The position of the XY stage 22 is measured by irradiating a laser beam from the stage position detector 135 onto the mirror 24 on the XY stage 22 and using the reflected light.

[0031] The multiple beams irradiated at one time are ideally arranged at a pitch obtained by multiplying the arrangement pitch of the plurality of openings 80 in the shaping aperture array substrate 8 by the desired reduction ratio described above. Note that the pitch of such multiple beams does not necessarily have to be constant. This drawing device performs drawing operations using a raster scan method in which shot beams are continuously irradiated in order, and when drawing a desired pattern, the beams required for the pattern are turned on by blanking control.

[0032] The drawing data processing unit 111 of the control computer 110 reads out the drawing data from the storage device 140, and performs multiple stages of data conversion to generate shot data. The shot data defines whether or not to irradiate each irradiation area obtained by dividing the drawing surface of the substrate 70 into a plurality of irradiation areas in a grid pattern, for example, by the beam size, as well as the irradiation time.

[0033] The writing control unit 112 outputs a control signal to the deflection control circuit 130 based on the shot data and stage position information. The deflection control circuit 130 controls the voltage applied to each blanker of the blanking aperture array substrate 10 based on the control signal. The deflection control circuit 130 also calculates deflection amount data so that the beam is irradiated at a desired position on the substrate 70, and outputs the data to the DAC amplifier 131. The DAC amplifier 131 converts the digital signal to an analog signal, amplifies it, and applies it to the deflector 17 as a deflection voltage. The deflector 17 deflects the multi-beams according to the applied deflection voltage.

[0034] In a drawing device, beam drift can occur due to the effects of contamination adhesion, etc., which can cause deviations in the beam irradiation position. For this reason, it is necessary to temporarily suspend the pattern drawing process at a predetermined timing, scan the mark M with multiple beams, measure the mark position, and adjust the irradiation position (drift correction).

[0035] 15, the mark M is not scanned by deflecting the multi-beams with the deflector 17, but the beam-on area is switched (shifted) to pseudo-scan the mark M. Hereinafter, scanning the mark M by deflecting the multi-beams (on-beams) with the deflector 17 will be referred to as "deflection scan," and pseudo-scanning the mark M by switching the beam-on area will be referred to as "switch scan."

[0036] An example of switch scanning is shown in Figures 3(a) to (d) and 4(a) to (c). First, as shown in Figure 3(a), a portion of the multi-beams in region BG1 is turned on, and the beams in other regions are turned off. In this example, of the 81 (=9 × 9) beams, 9 (=3 × 3) beams in region BG1 located in the upper left corner of the figure are turned on. A detector 26 detects the reflected electron signal from mark M. The width of mark M is smaller than the overall size of the multi-beams and larger than the pitch of the multi-beams on the substrate. The on-beam region includes multiple individual beams aligned along both the direction perpendicular to the mark edge E in the width direction WD of mark M and the direction parallel to the mark edge E in the width direction WD (the mark edge extension direction).

[0037] 3(b), the beam-on region is shifted one column to the right, and the beam of region BG2 is turned on. The detector 26 detects the backscattered electron signal from mark M.

[0038] Next, as shown in Figures 3(c), 3(d), 4(a), 4(b), and 4(c), the beam-on region is shifted to the right by one column at a time, and the beam is turned on in regions BG3, BG4, BG5, BG6, and BG7 in that order. Each time the beam-on region is switched, the detector 26 detects a backscattered electron signal from the mark M.

[0039] By switching the on-beam region from region BG1 to region BG7 in order, mark scanning similar to deflection scanning of mark M with the beam in region BG1 as shown in FIG. 15 becomes possible.

[0040] The detection result of the reflected electron signal by the detector 26 is ideally as shown in Fig. 5. The amount of reflected electrons from the mark M portion is greater than the amount of reflected electrons from portions other than the mark M. The mark position calculation unit 113 detects the peak of the amount of reflected electrons from the detection result of the reflected electron signal by the detector 26 and calculates the mark position.

[0041] However, if there is a distribution of the current amount within the beam array plane, it becomes difficult to identify the peak of the reflected electron amount caused by the mark. For example, if the beam in area BG1 has a larger beam current than the beams in other areas, the detection result of the reflected electron signal obtained by switch-scanning mark M will look like that shown in Figure 6, making it difficult to identify the peak caused by the mark.

[0042] Therefore, in this embodiment, the beam current of an individual beam or a group of beams formed by grouping multiple individual beams is detected within the beam array plane, and beams outside the area are also turned on so that the unit time average of the beam current on the mark substrate is constant between the on-beam areas used in switch scanning, and the number of beams to be turned on is changed when the on-beam area is switched.

[0043] For example, the current detector 50 is used to detect the beam current in each of the on-beam regions R1 to R6 used for switch scanning as shown in Fig. 7. The current detector 50 is also used to detect the beam current of an individual beam or a beam group at a position other than the regions R1 to R6 within the beam array plane. The current distribution calculation unit 116 calculates the current distribution within the beam array plane from the detection result of the current detector 50 and stores it in the storage device 142 as current amount information.

[0044] An example of the beam current in the regions R1 to R6 is shown in Fig. 8. When performing the switch scan, the writing control unit 112 refers to the current amount information and adjusts the number of beams to be turned on in the regions other than the regions R1 to R6 used in the switch scan based on the difference in beam current between the regions R1 to R6, so as to control the current of the beam irradiated onto the mark substrate 28 to have the same average per unit time.

[0045] A drawing method including drift correction using such switch scanning will be described with reference to the flowchart shown in FIG.

[0046] A multi-beam is irradiated onto the substrate 70 to draw a pattern (step S1). After a predetermined time has elapsed, when it is time to perform drift measurement (step S2_Yes), the pattern drawing is temporarily stopped and the mark M is switch-scanned (step S3).

[0047] As described above, beams other than those used in the switch scan are turned on based on the difference in beam current between the on-beam regions. The rough position of mark M is measured in advance, and beams that do not hit mark M are turned on. It is preferable that the beams to be turned on in regions other than R1 to R6 are not fixed but selected randomly.

[0048] For example, as shown in FIG. 10(a), when region R1 is turned on, multiple beams are turned on at positions outside the on-beam region for switch scanning (outside region R1) and not hitting mark M. In the figure, the beams that are turned on are shaded. Similarly, as shown in FIGS. 10(b) to 10(f), when regions R2 to R6 are turned on, one or multiple beams are turned on at positions outside the on-beam region for switch scanning and not hitting mark M. The smaller the beam current in regions R1 to R6, the greater the number of beams outside the on-beam region for switch scanning. Note that when beams outside the on-beam region are irradiated randomly, the random beams may hit mark M as long as it does not affect the measurement.

[0049] As shown in FIG. 10(d), in the region where the beam current is the largest (region R4 in this example), no beams may be turned on outside the region.

[0050] As a result, when performing a switch scan, the amount of beam current irradiated onto the mark substrate 28 is adjusted to the region (region R4) where the beam current is greatest. As a result, the detection result of the backscattered electron signal by the detector 26 becomes as shown in Figure 11 (solid line). The backscattered electron signal is flattened, and the gain and offset can be adjusted to maximize the peak caused by the mark, making it easier to detect the peak.

[0051] On the other hand, when switch scanning is performed without turning on the beams other than those in the regions R1 to R6, the detection result of the backscattered electron signal by the detector 26 becomes as shown in FIG. 11 (dashed line), making it difficult to distinguish the peaks caused by the marks.

[0052] The mark position calculation unit 113 calculates the mark position from the detection result of the reflected electron signal by the detector 26 as shown in FIG. 11, and measures the deviation of the mark position based on the calculated mark position and the stage position information detected by the stage position detector 135 (step S4).

[0053] The correction unit 114 calculates the correction amount (deflection correction amount) for correcting (calibrating) the deviation of the mark position using the deflector 17 (step S5). The calculated correction amount is stored in a storage device (not shown). In the subsequent pattern writing (step S1), the irradiation position (deflection position) of the multi-beam is deflected to a position shifted by the correction amount, thereby making it possible to adjust the irradiation position, such as for drift correction.

[0054] As described above, according to this embodiment, the mark M is pseudo-scanned by switching the on-beam area, thereby suppressing the occurrence of deflection distortion. Also, by turning on the beam in areas other than those used in the switch scan and making the unit time average of the beam current irradiated onto the mark substrate 28 the same, peaks caused by the mark can be easily detected from the detection results of the backscattered electron signal, and the mark position can be accurately measured. As a result, positional deviation due to beam drift can be corrected with high precision.

[0055] In the above embodiment, an example was described in which the beam other than that in regions R1 to R6 is turned on so that the beam current irradiated to the mark substrate 28 is adjusted to the region (region R4) with the largest beam current among the regions R1 to R6 used in switch scanning, but the beam current irradiated to the mark substrate 28 may also be adjusted to the region (region R1) with the smallest beam current.

[0056] For example, the beam current in each of the regions R1 to R6 is detected using the current detector 50, and it is determined how much the number of beams turned on in each region should be reduced to make the beam current the same as that in the region with the smallest beam current.

[0057] When performing switch scanning, by adjusting the amount of beam current irradiated onto the mark substrate 28 to the region where the beam current is smallest, the detection result of the backscattered electron signal by the detector 26 becomes as shown in Figure 12 (solid line), and the peak caused by the mark can be easily detected. The dashed line in Figure 12 shows the detection result of the backscattered electron signal when no control is performed to make the amount of beam current irradiated onto the mark substrate 28 constant.

[0058] To adjust the amount of current of the beam irradiated onto the mark substrate 28 to an arbitrary value, a process of turning on the beam outside the region and a process of reducing the number of beams turned on within the region may be combined.

[0059] In regions where the beam current is small (for example, regions R1 and R6), the beams outside the region are turned on. In regions where the beam current is large (for example, regions R2 to R5), the number of beams turned on within the region is reduced.

[0060] As a result, when performing switch scanning, the amount of current of the beam irradiated onto the mark substrate 28 becomes constant, and the detection result of the backscattered electron signal by the detector 26 becomes as shown in Fig. 13 (solid line), making it possible to easily detect peaks caused by the mark. The dashed line in Fig. 13 shows the detection result of the backscattered electron signal when no control is performed to make the amount of current of the beam irradiated onto the mark substrate 28 constant.

[0061] 3 and 4, the on-beam area is shifted by one column in the width direction (switch scan direction) of the mark M, but it may be shifted by multiple columns. However, the smaller the number of columns a by which the on-beam area is shifted, the more accurately the mark position can be measured. For example, it is preferable that the first on-beam area and the second on-beam area shifted by a columns overlap at least partially.

[0062] In the above embodiment, an example has been described in which mark M on XY stage 22 is switch-scanned, but it is also possible to switch-scan an alignment mark provided on substrate 70 when forming a phase shift mask. A method for drawing a pattern for a phase shift mask will be described with reference to the flowchart shown in FIG.

[0063] First, a substrate 70 is prepared in which a halftone film, a light-shielding film, and a resist film are laminated in this order on a glass substrate. The halftone film may be, for example, a MoSi film. The light-shielding film may be, for example, a Cr film. In the first-layer writing step (step S11), a first-layer main pattern, which will become the actual pattern, is written in the center of the substrate 70. Then, a cross-shaped mark pattern is written in a mark region around the first-layer main pattern.

[0064] The substrate 70 on which the first layer pattern and mark pattern have been drawn is subjected to development and etching processes (step S12). The development process removes the resist in the beam-irradiated area, forming a resist pattern. Using the resist pattern as a mask, the exposed light-shielding film and half-tone film are removed by etching. Thereafter, the resist film is removed by ashing or the like, thereby forming the first layer main pattern and its surrounding marks on the substrate 70.

[0065] Then, the substrate 70 on which a resist film has been formed is carried into the writing chamber 20. When writing the pattern of the second layer, the marks formed around the main pattern of the first layer are switch scanned, and the mark positions are calculated (steps S13 and S14). During the switch scan, as in the above embodiment, beams outside the region are turned on, or the number of beams turned on within the region is reduced, so that the amount of current of the beams irradiated onto the substrate 70 is the same.

[0066] Alignment calculation is performed based on the calculated mark positions, and a second-layer main pattern is written at the aligned position on substrate 70 (step S15). Substrate 70 on which the second-layer pattern has been written is developed and etched to form the second-layer pattern (step S16). In this manner, a phase shift mask can be manufactured.

[0067] The position of the mark formed together with the first layer pattern can be measured with high precision by switch scanning, enabling highly accurate alignment, thereby reducing mask loss due to misalignment.

[0068] Such switch scanning can be used not only for the drift correction and phase shift mask alignment described above, but also for adjusting the drawing position to avoid dust defects on the EUV mask, thereby reducing phase defects and other defects in the pattern during EUV exposure.

[0069] In the above embodiment, a configuration was described in which, when performing switch scanning, beams outside the region (e.g., other than regions R1 to R6) are turned on or the number of beams turned on within the region (e.g., within regions R1 to R6) is reduced so that the unit time average of the beam current irradiated onto the substrate on which a mark is formed is the same before and after switching the beam-on region. However, the beam-on time may also be controlled by turning the beam on / off. For example, in a region with a large beam current, the beam-on time is made shorter than in a region with a small beam current. The beam may be repeatedly turned on / off to change the shot cycle so that the unit time average of the beam current irradiated onto the substrate is the same.

[0070] In the above embodiment, a configuration has been described in which a current detector 50 such as a Faraday cup is used to detect the beam current of an individual beam or a group of beams within the beam array plane, and based on the detection results, beams outside the region are turned on or the number of beams within the region that are turned on is reduced. However, it is also possible to irradiate a beam onto a portion other than the mark on the mark substrate 28, detect reflected electrons with the detector 26, and determine the beams to be turned on outside the region or the beams to be turned on within the region, or control the beam-on time, so that the average amount of detected reflected electrons per unit time is the same.

[0071] In the above embodiment, an example of a multi-beam lithography apparatus has been described, but the present invention can also be applied to a multi-beam inspection apparatus. For example, a multi-beam inspection apparatus includes a primary optical system that irradiates a substrate 70 to be inspected on an XY stage 22 with multiple beams 30 as primary beams, and a secondary optical system that guides multiple secondary electrons emitted from the substrate to a detector. The primary optical system includes an illumination lens 6, a shaping aperture array substrate 8, a blanking aperture array substrate 10, a reduction lens 12, an objective lens 15, a deflector 17, etc. (see FIG. 1).

[0072] As shown in FIG. 16, the secondary optical system includes a beam separator 214, a projection lens 224, an alignment coil 232, and the like. When the multibeam 30 is irradiated onto the substrate 70, a bundle of secondary electrons (multi-secondary electrons 300) including reflected electrons corresponding to each beam of the multibeam 30 is emitted from the substrate 70 (dotted lines in FIG. 16). The beam separator 214 (e.g., a Wien filter) generates an electric field and a magnetic field in perpendicular directions on a plane perpendicular to the direction (optical axis) of travel of the multibeam 30. The electric field exerts a force in the same direction regardless of the direction of travel of the electrons. In contrast, the magnetic field exerts a force according to Fleming's left-hand rule. Therefore, the direction of the force acting on the electrons can be changed depending on the direction of entry of the electrons. When the multibeam 30 (primary electron beam) enters the beam separator 214 from above, the force due to the electric field and the force due to the magnetic field cancel each other out, causing the multibeam 30 to travel straight downward. In contrast, the multiple secondary electrons 300 entering the beam separator 214 from below are subjected to both the force of the electric field and the force of the magnetic field in the same direction, causing the multiple secondary electrons 300 to bend obliquely upward.

[0073] The multiple secondary electrons 300 bent obliquely upward are projected onto the detector 222 while being refracted by the projection lens 224. The detector 222 collectively detects the projected multiple secondary electrons 300. The detector 222 has, for example, a diode-type sensor (not shown).

[0074] In this way, the inspection device is provided with a primary electron optical system that adjusts the trajectories of the multi-beams 30 (primary electron beams) and a secondary electron optical system that adjusts the trajectories of the multi-secondary electrons 300 (secondary electrons).

[0075] The mark M on the mark substrate 28 is scanned with multiple beams, the mark position is measured, and the measurement results are used to adjust the primary electron optical system. At this time, as in the above embodiment, the on-beam region is sequentially switched to switch-scan the mark M, and the beams outside the region are turned on or the number of beams turned on within the region is adjusted so that the unit time average of the current of the beam irradiated on the mark substrate 28 is the same.

[0076] The present invention is not limited to the above-described embodiments, and the components can be modified and embodied in practice without departing from the spirit of the invention. Furthermore, various inventions can be created by appropriately combining multiple components disclosed in the above-described embodiments. For example, some components may be omitted from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined. [Explanation of symbols]

[0077] 1. Drawing section 2 Electron optical column 4 Electron source 6 Lighting lens 8. Shaped aperture array substrate 10 Blanking aperture array substrate 12. Reduction Lens 14 Limiting aperture member 15 Objective Lens 17 Deflector 20 Drawing room 22 XY stage 28 Mark board 50 Current detector 100 control section 110 Control computer

Claims

1. forming a multi-beam of charged particle beams arranged at a predetermined pitch; sequentially switching on-beam regions in which beams in some regions of the multi-beam are turned on, and shifting the irradiation position of the charged particle beam, thereby pseudo-scanning a mark provided at a predetermined position and having a width wider than the predetermined pitch, and detecting a reflected charged particle signal from the mark; A mark position measuring method for measuring the position of the mark based on the detected reflected charged particle signal, comprising: A mark position measuring method, wherein an average per unit time of the beam current on the substrate on which the mark is formed is kept constant when the on-beam region is switched.

2. 2. The mark position measuring method according to claim 1, wherein the number of said beams that are turned on is changed to keep the average of said beam current per unit time constant.

3. 3. The mark position measuring method according to claim 2, further comprising adjusting the number of beams turned on outside the on-beam region for pseudo-scanning the mark.

4. 3. The mark position measuring method according to claim 2, further comprising adjusting the number of beams turned on within the on-beam region for pseudo-scanning the mark.

5. 2. The mark position measuring method according to claim 1, wherein the beam-on time is changed for each of the on-beam regions to keep the beam current constant on average per unit time.

6. A multi-charged particle beam writing method, which writes a pattern by adjusting the irradiation positions of the multi-beams based on the positions of the marks measured by the mark position measuring method according to any one of claims 1 to 5.

7. an aperture array substrate for forming a multi-beam charged particle beam arranged at a predetermined pitch; a stage on which a pattern drawing target is placed; a mark formed on the mark substrate or the pattern drawing target on the stage, the mark having a width wider than the predetermined pitch; a control unit that sequentially switches on-beam regions in which beams in some regions of the multi-beam are turned on, and shifts the irradiation position of the charged particle beam to thereby pseudo-scan the mark; a detector for detecting a reflected charged particle signal from the mark; a mark position calculation unit that calculates the position of the mark based on the detected reflected charged particle signal; Equipped with The control unit maintains a constant unit time average of the beam current on the mark substrate or the pattern drawing target when switching the on-beam region.

8. 8. The multi-charged particle beam drawing apparatus according to claim 7, wherein said control unit changes the number of said beams to be turned on to keep the average of said beam current per unit time constant.

9. 8. The multi-charged particle beam drawing apparatus according to claim 7, wherein the control unit changes a beam-on time for each of the on-beam regions to keep the unit time average of the beam current constant.

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