Charged particle beam drawing method, charged particle beam drawing apparatus, and program

Abstract

A method is provided that can correct defects that are outside the absorber pattern area due to irreversible deformation of the EUV mask substrate caused by irradiation with a charged particle beam. [Configuration] A charged particle beam writing method according to one aspect of the present invention is characterized by comprising the steps of: determining a positional deviation distribution, which defines the positional deviation from the designed position of the sample caused by the irreversible deformation of the sample at each position of the sample at the time of irradiating the charged particle beam on the sample, which has a substrate body, a light-reflecting laminate disposed on the substrate body, and an absorber film disposed on the laminate that absorbs light; using the positional deviation distribution, calculating a correction amount for the irradiation position of the charged particle beam so that defects generated in the sample are included in the area where the absorber film remains after writing; and correcting the irradiation position using the correction amount and writing a pattern on the sample with the charged particle beam.

Description

[Technical Field]

[0001] One aspect of the present invention relates to a charged particle beam lithography method, a charged particle beam lithography apparatus, and a program, and relates to, for example, a technique for lithography a pattern on a substrate that is irreversibly deformed by irradiation with an electron beam. [Background technology]

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

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

[0004] Here, a reflective optical system has been proposed for exposure methods using EUV light. For this purpose, a reflective mask with a multilayer film formed on a substrate is used. The multilayer film is made up of alternating layers of molybdenum (Mo) and silicon (Si).

[0005] If the thickness regularity of each layer in the stack is disrupted, the phase of the reflected light will shift. As a result, these defects will be exposed on the wafer as phase defects. Therefore, it is desirable to have zero defects on the surface of the multilayer substrate. Furthermore, it is desirable to prevent the introduction of foreign matter that could cause defects during the stacking of the multilayer. However, it is difficult to completely eliminate defects on the substrate. If all manufactured masks were to be inspected and only those with zero defects or that meet the specifications were to be selected, the substrates would become very expensive. Therefore, a technique has been disclosed in which the mask is formed by offsetting the pattern position so that the defects are contained within the absorber pattern area to prevent the defects from being transferred during the exposure process, thereby preventing the transfer of phase defects on the multilayer mask (see, for example, Patent Document 1).

[0006] Furthermore, while pattern position accuracy is important for mask substrates, one of the factors that degrades global pattern position accuracy is the reversible deformation of the glass substrate used as the sample, which occurs when the glass substrate is heated by electron beam irradiation and then contracts. This deformation of the glass substrate can cause misalignment of the beam irradiation position or the pattern formation position.

[0007] To address this issue, glass substrate blank manufacturers have developed low-thermal expansion substrates (LTEM: low-thermal expansion material) that minimize the thermal expansion of the substrate itself. These LTEM substrates exhibit minimal thermal expansion due to the temperature rise associated with electron beam irradiation, thereby minimizing substrate deformation. This has solved problems such as misalignment due to reversible deformation associated with thermal expansion. However, it has been discovered that electron beam irradiation can cause irreversible shrinkage of glass substrates. This is due to factors such as increased beam doses resulting from lower resist sensitivity to improve local dimensional accuracy, and the widespread use of LTEM substrates, which have made thermal expansion negligible and relatively significant shrinkage of glass substrates. This deformation due to irreversible shrinkage of glass substrates has led to problems such as deterioration of the global positional accuracy of beam irradiation positions and pattern formation positions.

[0008] As a result, even if the position of the EUV mask pattern is offset by a conventional method so that the defect is contained within the absorber pattern area, the deformation caused by this irreversible substrate shrinkage phenomenon causes the defect to move out of the absorber pattern area and into the laminated film area. This problem occurs in both multi-beam and single-beam writing. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-043100 Summary of the Invention [Problem to be solved by the invention]

[0010] One aspect of the present invention provides a method, an apparatus, etc. that can correct defects that are outside the absorber pattern area due to irreversible deformation of an EUV mask substrate caused by irradiation with a charged particle beam. [Means for solving the problem]

[0011] A charged particle beam writing method according to one aspect of the present invention includes: a step of determining a positional deviation distribution, which defines the positional deviation amount from a design position of the sample caused by the irreversible deformation of the sample at each position of the sample at the time of irradiating the charged particle beam on the sample, the sample having a substrate body, a laminated body that reflects light and that is disposed on the substrate body, and an absorber film that absorbs light and that is disposed on the laminated body; calculating a correction amount for the irradiation position of the charged particle beam using the positional deviation distribution so that the defect generated in the sample is included in the region where the absorber film remains after writing; correcting the irradiation position using the correction amount and drawing a pattern on the sample with the charged particle beam; The present invention is characterized by the following features.

[0012] The method further comprises a step of correcting the irradiation position of the charged particle beam using defect position information indicating the defect position without taking into consideration the positional deviation amount distribution, When performing correction using the positional deviation distribution, it is preferable that the irradiation position of the charged particle beam corrected without taking the positional deviation distribution into consideration is further corrected taking the positional deviation distribution into consideration.

[0013] Also, a step of determining a dose distribution of the charged particle beam irradiated onto a plurality of processing regions obtained by dividing the writing region of the sample into a mesh pattern; generating a strain distribution using the dose distribution to define the strain at each location on the sample caused by irreversible deformation of the sample; It is preferable that the device further comprises:

[0014] A charged particle beam lithography apparatus according to one aspect of the present invention comprises: a positional deviation amount distribution calculation unit that creates a positional deviation amount distribution that defines the positional deviation amount from a design position of the sample caused by the irreversible deformation of the sample at each position of the sample at the time of irradiating the charged particle beam, the positional deviation amount distribution being defined for the sample that has a substrate body, a laminate that is arranged on the substrate body and reflects EUV light, and an absorber film that is arranged on the laminate and absorbs EUV light, and that irreversibly deforms depending on the irradiation dose distribution of the charged particle beam; a correction amount calculation unit that calculates a correction amount for the irradiation position of the charged particle beam using the positional deviation amount distribution so that a defect generated in the sample is included in a region where the absorber film remains after writing; a drawing mechanism that draws a pattern on a sample using a charged particle beam whose irradiation position has been corrected by the correction amount; The present invention is characterized by the following features.

[0015] A program according to one aspect of the present invention comprises: a process for creating a positional deviation distribution, which defines the positional deviation amount from the design position of the sample caused by the irreversible deformation of the sample at each position of the sample at the time of irradiating the charged particle beam, on the sample having a substrate body, a laminated body that reflects EUV light and is disposed on the substrate body, and an absorber film that absorbs EUV light and is disposed on the laminated body; and a process of storing the generated positional deviation amount distribution in a storage device; a process of reading out the positional deviation amount distribution from the storage device, and calculating and outputting a correction amount for the irradiation position of the charged particle beam using the positional deviation amount distribution so that defects occurring in the sample are included in an area where the absorber film remains after writing; to be executed by the computer. [Effects of the Invention]

[0016] According to one aspect of the present invention, it is possible to correct defects that are outside the absorber pattern region due to irreversible deformation of the EUV mask substrate caused by irradiation with a charged particle beam. [Brief explanation of the drawings]

[0017] [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 diagram showing an example of an evaluation board according to the first embodiment. [Figure 5] 5 is a diagram showing an example of the relationship between the amount of positional misalignment of an evaluation substrate and an example of deformation of the substrate in the first embodiment. FIG. [Figure 6] 4 is a diagram showing an example of a state when a beam is irradiated onto an evaluation substrate in the first embodiment. FIG. [Figure 7] 5A and 5B are diagrams showing an example of a stress state caused by beam irradiation on an evaluation substrate in the first embodiment. [Figure 8] FIG. 10 is a diagram showing an example of a cross section of an EUV mask in which a defect exists in a reflective region according to a first comparative example of the first embodiment. [Figure 9] FIG. 2 is a diagram showing an example of a cross section of an EUV mask in which a defect exists in an absorber region according to the first embodiment. [Figure 10] 10 is a top view showing an example of the positional relationship between a defect and an absorber film at a time point before the defect location is written in Comparative Example 2 of Embodiment 1. FIG. [Figure 11] 10 is a top view showing an example of the positional relationship between a defect and an absorber film when the defect portion is written in Comparative Example 2 of Embodiment 1. FIG. [Figure 12] FIG. 2 is a flowchart showing an example of main steps of the writing method according to the first embodiment. [Figure 13] FIG. 2 is a diagram showing a configuration of a sample according to the first embodiment. [Figure 14] FIG. 2 is a diagram showing an example of the positional relationship between a pattern layout and a defect according to the first embodiment. [Figure 15] 3A to 3C are conceptual diagrams for explaining an example of each region on a sample and an example of a writing operation in the first embodiment. [Figure 16]3 is a diagram showing an example of a multi-beam irradiation area and a pixel to be written in the first embodiment. FIG. [Figure 17] FIG. 4 is a diagram showing an example of the relationship between the reduction rate of the substrate and the dose amount in the first embodiment. [Figure 18] FIG. 2 is a diagram showing an example of a model based on a finite element method according to the first embodiment. [Figure 19] FIG. 2 is a diagram for explaining an example of a multi-beam writing operation according to the first embodiment. [Figure 20] 4 is a top view showing an example of the positional relationship between a defect and an absorber film when the defect portion is written in the first embodiment. FIG. [Figure 21] 10 is a top view showing an example of the positional relationship between a defect and an absorber film after writing in the first embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] In the following embodiments, a configuration using an electron beam will be described as an example of a charged particle beam. However, the charged particle beam is not limited to an electron beam, and a beam using charged particles such as an ion beam may also be used. Furthermore, in the embodiments, a case where a multi-beam consisting of multiple electron beams is used will be described. However, the correction method described below is not limited to a multi-beam, and can also be applied to a case where a single beam is used.

[0019] 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 deflector 208, a deflector 209, and a detector 212 are arranged.

[0020] An XY stage 105 is placed in the writing chamber 103. A sample 101, such as a mask, which serves as a substrate to be written during writing (exposure) is placed on the XY stage 105. For example, the backside of the sample 101 is supported at three points by three rod-shaped support members (not shown). The sample 101 includes a mask for EUV exposure when manufacturing a semiconductor device or the like. The sample 101 also includes a mask blank coated with resist and on which nothing has yet been written. A low thermal expansion (LTEM) substrate is used as the glass substrate for the sample 101. The sample 101 has a substrate body, which is an LTEM substrate, a stacked body that reflects EUV light and is placed on the substrate body, and an absorber film that absorbs EUV light and is placed on the stacked body. Resist is then applied to the surface.

[0021] Furthermore, a mirror 210 for measuring the position of the XY stage 105 is also arranged on the XY stage 105 .

[0022] The control system circuit 160 includes a control computer 110, a memory 112, a deflection control circuit 130, digital-to-analog conversion (DAC) amplifier units 132 and 134, a lens control circuit 136, a detection circuit 137, 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 detection circuit 137, the stage control mechanism 138, the stage position measurement device 139, and 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 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 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 electromagnetic lenses, such as the illumination lens 202, the reduction lens 205, and the objective lens 207, are controlled by a lens control circuit 136.

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

[0024] The detector 212 detects secondary electrons emitted from the sample surface when the sample surface is irradiated with the electron beam for mark measurement. The detected signal is output to the detection circuit 137, where it is amplified and converted into digital data, and then output to the control computer 110.

[0025] The control computer 110 includes an irradiation dose distribution creation unit 50, a distortion amount distribution creation unit 52, a deformation amount distribution creation unit 54, a misalignment amount distribution calculation unit 56, a correction amount calculation unit 57, a correction unit 58, a defect coordinate conversion unit 60, a corrected layout data generation unit 62, 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 irradiation dose distribution creation unit 50, the distortion amount distribution creation unit 52, the deformation amount distribution creation unit 54, a misalignment amount distribution calculation unit 56, a correction amount calculation unit 57, the correction unit 58, the defect coordinate conversion unit 60, the corrected layout data generation unit 62, the shot data generation unit 70, the data processing unit 72, the transfer processing unit 74, and the writing control unit 76, has a processing circuit. Such a processing circuit may include, for example, an electric circuit, a computer, a processor, a circuit board, a quantum circuit, or a semiconductor device. Each of the "~ units" may use a common processing circuit (the same processing circuit) or may use a different processing circuit (separate processing circuit). Information input to and output from the dose distribution creation unit 50, distortion distribution creation unit 52, deformation distribution creation unit 54, positional deviation distribution calculation unit 56, correction amount calculation unit 57, correction unit 58, defect coordinate conversion unit 60, corrected layout data generation unit 62, shot data generation unit 70, data processing unit 72, transfer processing unit 74, and writing control unit 76, as well as information being calculated, are stored in memory 112 each time.

[0026] 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.

[0027] 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 graphic patterns that make up the chip pattern. Specifically, for example, a coordinate sequence of each vertex coordinate is defined for each graphic pattern. It is also preferable that other data such as a graphic code be defined. Alternatively, the graphic code, coordinates, and size may be defined.

[0028] Furthermore, defect information about defects on the sample 101 is input from outside the writing apparatus 100 and stored, for example, in the storage device 144. The defect information defines the position (coordinates) and size of defects on the sample 101 measured by the defect measurement device.

[0029] 1 shows the configuration necessary for explaining the first embodiment. The drawing device 100 may also include other configurations that are normally required.

[0030] 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.

[0031] 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 formed on a support substrate 33 and uses a semiconductor substrate made of silicon or the like. 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.

[0032] 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.

[0033] 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).

[0034] 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 deflectors 208 and 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, the deflector 208 performs tracking control 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.

[0035] By using an LTEM substrate as the main substrate portion of the sample to be written, thermal expansion due to irradiation with a single or multiple electron beams is virtually eliminated. Therefore, the problem of misalignment of the writing position due to thermal expansion is greatly improved to the point that it can be ignored. However, it has been discovered that the accumulation of dose due to multiple electron beam irradiations can cause irreversible shrinkage of the glass substrate that forms the main substrate of the sample 101.

[0036] FIG. 4 is a diagram illustrating an example of an evaluation substrate according to the first embodiment. An LTEM substrate is used as the evaluation substrate. Specifically, a mask blank is used in which, for example, a chromium (Cr) film is formed on the LTEM substrate and a resist film is formed on the Cr film. FIG. 4 illustrates an example of a pattern after three drawing processes. Each drawing process is performed in the y direction from the bottom to the top of the evaluation substrate. In the first drawing process (1S), multiple cross patterns are drawn in a grid pattern across the entire evaluation substrate. In the second drawing process (2S), L-shaped patterns are drawn near each cross pattern, for example, in the upper right and lower left, and rectangular patterns with different pattern densities are drawn in the lower and upper halves of the evaluation substrate as a background for the multiple cross patterns. For example, the background of the lower half, which is drawn in the first half, has a pattern density of, for example, 3%. The background of the upper half, which is drawn in the second half, has a pattern density of, for example, 75%. In the third drawing process (3S), L-shaped patterns are drawn near each cross pattern, for example, in the upper left and lower right. After each drawing process, the position of each drawn pattern is measured. The position of the pattern is measured by a position measuring device (not shown).

[0037] 5 is a diagram showing an example of the relationship between the amount of misalignment of an evaluation substrate and an example of deformation of the substrate in embodiment 1. Fig. 5 shows an example of a graph of the amount of misalignment Δx in the x direction in the state (2S-1S) obtained by subtracting the position of each pattern after writing process 1S from the position of each pattern after writing process 2S. As shown in the graph (2S-1S), the amount of misalignment Δx is small when the background pattern density is 3%, whereas when the background pattern density is 75%, the amount of misalignment Δx increases as the area written is increased. This shows that deformation due to shrinkage of the glass substrate increases depending on the irradiation dose. Figure 5 also shows an example graph of the x-direction misalignment Δx and the y-direction misalignment Δy for the (3S-1S) state, which is the difference between the position of each pattern after 3S and the position of each pattern after 1S. As shown in the (3S-1S) graph, the misalignment Δx at 2S remains even after 3S. It can also be seen that the lower half of the substrate deforms in response to the shrinkage of the upper half, and by 3S, the substrate position shifts, increasing the misalignment Δx. It can also be seen that the misalignment ΔY in the y-direction gradually increases in the upper half of the substrate. This is due to the fact that the upper half of the substrate is irradiated with a relatively large beam dose, causing significant deformation due to shrinkage, as shown in the lower right diagram of Figure 5. As shown in this figure, 2S causes large shrinkage and deformation in the upper half of the substrate.

[0038] FIG. 6 is a diagram showing an example of a state when a beam is irradiated onto an evaluation substrate according to the first embodiment. FIG. 7 is a diagram showing an example of a stress state caused by beam irradiation on an evaluation substrate according to the first embodiment. As described above, the evaluation substrate shown in FIG. 6 is a mask blank in which, for example, a chromium (Cr) film 13 is formed on an LTEM substrate 12 and a resist film 16 is formed on the Cr film 13. When an electron beam is irradiated onto this evaluation substrate, the electron beam reaches the LTEM substrate 12 and penetrates several tens of micrometers from the surface of the LTEM substrate 12. This causes irreversible local contraction at the irradiated position of the LTEM substrate 12. Because the beam is irradiated at multiple locations, tensile stress is generated near the substrate surface due to the local contraction throughout the entire beam-irradiated area. This causes irreversible deformation due to the contraction phenomenon near the surface of the LTEM substrate 12. Note that, because a deformation of a depth of, for example, 20 μm is small in volume compared to the thickness of the LTEM substrate 12 (e.g., 6.35 mm), the thermal deformation of the entire substrate does not change. Therefore, reversible deformation due to thermal expansion can be ignored.

[0039] FIG. 8 is a diagram showing an example of a cross section of an EUV mask in which a defect exists in a reflective region in Comparative Example 1 of the first embodiment. FIG. 9 is a diagram showing an example of a cross section of the EUV mask according to the first embodiment, in which a defect exists in an absorber region. In the EUV mask, a multilayer film 17 is formed on the entire surface of the LTEM substrate 12. The multilayer film 17 is made of, for example, several dozen layers of molybdenum (Mo) and silicon (Si) stacked alternately. A cap film 18 made of ruthenium (Ru) or the like is then formed on the entire surface of the multilayer film 17. The cap film 18 is exposed in the region that reflects EUV light. On the other hand, in the region that does not reflect EUV light, an absorber film 19 that absorbs EUV light and an anti-reflection film 21 are sequentially formed on the cap film 18. As shown in FIG. 8 , if a defect 40 in the multilayer film 17 exists in a region 42 where the absorber film 19 does not exist, the phase of the reflected EUV light will be shifted. As a result, when a pattern is transferred onto a semiconductor wafer using the manufactured EUV mask, the pattern position will be shifted. Therefore, in the first embodiment, as shown in FIG. 9 , after patterning, the pattern layout is shifted from the position shown in FIG. 8 so that the position of the defect 40 is included in a region 44 where the absorber film 19 exists. In other words, the sample 101, which is an EUV mask blank coated with a resist film, is patterned using the lithography system 100. The resist is developed, and the anti-reflection film 21 and the absorber film 19 are etched using the resist pattern formed by the resist film remaining after development as a mask. The remaining resist film is then removed by ashing, thereby patterning the sample 101. An EUV mask is manufactured by this patterning. After this patterning, the pattern layout is shifted when the lithography system 100 is used to draw the defect 40 so that the defect 40 is located within the region 44 where the absorber film 19 is present. To shift the pattern layout, it is first necessary to identify the defect position. To achieve this, the position of the defect 40 is first identified by performing a phase defect inspection of the sample 101 using a phase defect inspection system (not shown) before drawing.

[0040] FIG. 10 is a top view showing an example of the positional relationship between a defect and an absorber film at a time point before the defect portion is written in Comparative Example 2 of Embodiment 1. In FIG. FIG. 11 is a top view showing an example of the positional relationship between the defect and the absorber film when the defect portion is written in Comparative Example 2 of Embodiment 1. In Comparative Example 2, as shown in FIG. 9 , before writing begins, the pattern layout is offset in advance so that the defect 40 will be included in the absorber film 19 pattern after writing, and then writing is performed. In this case, while approximately half of the writing area is written, the position of the defect 40 is physically moved due to the irreversible substrate deformation described above, as shown in FIG. 10 . Then, by the time the electron beam is irradiated onto the area where the defect 40 exists, as shown in FIG. 11 , the position of the defect 40 has further physically moved. Therefore, when the electron beam is irradiated onto the area where the defect 40 exists in the defect information, the position of the defect 40 may be outside the pattern where the absorber film 19 remains. This results in the defect 40 being located in the reflection area of ​​the multilayer film 17 where the absorber film 19 is not present, as shown in FIG. 8 . As a result, when a pattern is transferred onto a semiconductor wafer using the manufactured EUV mask, the phase of the reflected EUV light is shifted, resulting in a shift in the position of the pattern.

[0041] Therefore, in the first embodiment, before starting writing, the distribution of the positional deviation amount of the substrate body (LTEM substrate 12) of the sample 101 at the time when the location where the defect 40 exists is irradiated with the electron beam is acquired in advance. Then, a correction is performed by adding the positional deviation amount of the substrate due to irreversible substrate deformation to the offset amount for the layout offset data so that the defect at the position defined in the defect information is included in the absorber film area. This will be explained in detail below.

[0042] Fig. 12 is a flowchart showing an example of main steps of the writing method according to the embodiment 1. In Fig. 12, the writing method according to the embodiment 1 carries out a series of steps including a reference mark measurement step (S102), a defect coordinate conversion step (S104), a corrected layout data generation step (S106), a dose map creation step (S108), a writing schedule creation step (S110), an irradiation dose distribution creation step (S112), a distortion amount distribution creation step (S114), a deformation amount distribution creation step (S116), a positional deviation amount distribution creation step (S118), a determination step (S120), a data correction step (S130), and a writing step (S140).

[0043] In the fiducial mark measurement step (S102), under the control of the writing control unit 76, the writing mechanism 150 scans the fiducial mark formed on the sample 101 to measure the position of the fiducial mark.

[0044] FIG. 13 is a diagram showing the structure of the sample according to the first embodiment. In FIG. 13, multiple fiducial marks 14 are arranged around the writing region 30 of the sample 101. For example, a cross pattern is preferably used as each fiducial mark 14. First, the XY stage 105 is moved so that one of the multiple fiducial marks 14 is within the irradiation range of the electron beam. Then, for example, the fiducial mark 14 is scanned with a representative beam (e.g., the central beam) of the multi-beam 20. Specifically, beams other than the representative beam are set to beam-off by the blanking aperture array mechanism 204. Then, the representative beam is deflected by, for example, the main deflector 208, so that the representative beam scans the region including the fiducial mark 14. Secondary electrons emitted from the sample 101 by the scanning are detected by the detector 212. The detection circuit 137 converts the secondary electrons into digital data and outputs them to the control computer 110. The other fiducial marks 14 are scanned in the same manner. The writing control unit 76 measures the positions of each fiducial mark obtained by the scanning. When drawing, a position on the sample surface is defined using at least two of the multiple reference marks 14. Therefore, the pattern layout to be drawn is adjusted to a coordinate system starting from the reference marks 14. This allows the pattern to be drawn at a desired position on the sample 101 even if the placement position of the sample 101 on the stage is misaligned.

[0045] In the defect coordinate conversion step (S104), the defect coordinate conversion unit 60 reads out the defect information from the storage device 144 and converts the position of the defect defined in the defect information into the position (coordinate) of the defect relative to the reference mark 14. The coordinate system in which the coordinates of the defect defined by the defect measurement device are defined may differ from the coordinate system generated based on the reference mark 14. Therefore, the defect coordinate conversion unit 60 converts the position of the defect defined in the defect information into the position (coordinate) of the defect relative to the reference mark 14.

[0046] In the corrected layout data generating step (S106), the corrected layout data generating unit 62 generates corrected layout data in which the position of the pattern layout is offset.

[0047] FIG. 14 is a diagram showing an example of the positional relationship between the pattern layout and the defect in the first embodiment. As described above, it is unknown whether the pattern layout to be written will be able to include the defect 40 within the region of the absorber film 19 pattern. Therefore, the corrected layout data generation unit 62 corrects the defect 40 obtained based on the fiducial mark 14 by offsetting the position of the pattern layout so that it is included within the region of the absorber film 19 pattern. The example of FIG. 14 shows a case where the writing region 30 (chip region) is offset to a position where the defect 40 is included within the region of the absorber film 19 pattern. Data of such an offset pattern layout is stored, for example, in the memory device 140. If multiple defects exist on the sample, the position of the pattern layout is offset so that as many defects as possible are included within the region of the absorber film 19 pattern. If the number of defects that cannot be included within the region of the absorber film 19 pattern even after correction exceeds the allowable number, the process terminates as an error.

[0048] 15 is a conceptual diagram for explaining an example of each region on a sample and an example of a writing operation in embodiment 1. As shown in Fig. 15, the position of a writing region 30 (bold line) on a sample 101 is defined based on the position of a reference mark 14. The writing area 30 (bold line) is virtually divided into a plurality of rectangular stripe areas 32 with a predetermined width in the y direction, for example. The example in Figure 15 shows a case where the writing area 30 on the sample 101 is divided into a plurality of stripe areas 32 with a width substantially equal to the size of the designed irradiation area 34 (beam array area) 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.

[0049] 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.

[0050] Next, the irradiation area 34 of the multibeam 20 is adjusted to be located 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. Thereafter, drawing is similarly performed in order from the lower stripe area 32 toward the upper side (y direction).

[0051] 15 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, the multi-beam 20 formed by passing through each hole 22 in the shaping aperture array substrate 203 simultaneously forms multiple shot patterns, up to the same number as the holes 22.

[0052] FIG. 16 shows an example of a multibeam irradiation area and a target pixel for drawing in the first embodiment. In FIG. 16, the stripe area 32 is divided into a plurality of mesh areas, for example, based on the beam size of the multibeam 20. Each mesh area corresponds to a target pixel 36 (unit irradiation area, irradiation position, or drawing position). The size of the target pixel 36 is not limited to the beam size and may be any size regardless of the beam size. For example, the target pixel 36 may be 1 / n (n is an integer greater than or equal to 1) of the beam size. The example of FIG. 16 shows a case where the target region for drawing on the sample 101 is divided, for example, in the y direction, into a plurality of stripe areas 32, each having a width substantially equal to the size of the irradiation region 34 (drawing field) that can be irradiated with one irradiation of the multibeam 20. The size of the rectangular irradiation region 34 in the x direction can be defined by the number of beams in the x direction multiplied by the beam pitch in the x direction. The size of the rectangular irradiation region 34 in the y direction can be defined by the number of beams in the y direction multiplied by the beam pitch in the y direction. In the example of FIG. 16, for example, a 512×512 array of multi-beams is shown as an 8×8 array of multi-beams. A plurality of pixels 28 (beam drawing positions) that can be irradiated with one shot of the multi-beam 20 are shown within the irradiation area 34. The pitch between adjacent pixels 28 is the pitch between each beam of the multi-beam. A rectangular area surrounded by the size of the beam pitch in the x and y directions constitutes one sub-irradiation area 29 (pitch cell). In the example of FIG. 16, each sub-irradiation area 29 is shown as being composed of, for example, 4×4 pixels.

[0053] In the dose map creation step (S108), the shot data generation unit 70 creates a dose map in which a dose amount is defined for each pixel, which will be described later. Specifically, the shot data generation unit 70 operates as follows: First, as a rasterization process, the shot data generation unit 70 calculates, for each pixel 36, a pattern area density ρ′ of the pattern to be placed in the neighboring mesh region.

[0054] Next, the shot data generation unit 70 virtually divides the writing region (for example, a stripe region) 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 dose map creation unit 50 reads out 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.

[0055] Next, the shot data generation unit 70 calculates a proximity effect corrected dose Dp(x) for correcting the proximity effect for each proximity mesh region. The unknown proximity effect corrected dose Dp(x) can be defined by a threshold model for proximity effect correction similar to conventional methods, using a backscattering coefficient η, a dose threshold Dth of a threshold model, a pattern area density ρ", and a distribution function g(x). The proximity effect corrected dose Dp(x) is calculated as a relative value normalized with the base dose Dbase set to 1.

[0056] Next, the shot data generation unit 70 calculates, for each pixel, an incident irradiation dose D(x) (dose) for irradiating the pixel. The incident irradiation dose D(x) may be calculated, for example, as the value obtained by multiplying the base irradiation dose Dbase by the proximity effect-corrected irradiation dose Dp and the pattern area density ρ'. The base irradiation dose Dbase may be defined, for example, as Dth / (1 / 2 + η). As a result, the proximity effect-corrected incident irradiation dose D(x) for each pixel can be obtained based on the layout of multiple graphic patterns defined in the drawing data. Alternatively, the shot data generation unit 70 may preferably define the incident irradiation dose D(x) for each pixel as an incident irradiation dose D(x) normalized by setting the base irradiation dose Dbase to 1. In this case, the incident irradiation dose D(x) may be calculated, for example, as the value obtained by multiplying the proximity effect-corrected irradiation dose Dp by the pattern area density ρ'.

[0057] Next, the shot data generation unit 70 creates a dose map whose elements are the incident irradiation dose D(x) of each pixel 36. In other words, each pixel (position) (x, y) is defined in association with the incident irradiation dose D(x) of that pixel. The created dose map is stored in the storage device 142. The shot data generation unit 70 creates a dose map for the entire drawing region 30 where drawing processing is performed in accordance with the drawing data (chip data).

[0058] In the writing schedule creation step (S110), the writing control unit 76 creates a writing schedule that defines the shot order for each pixel defined in the dose map. This allows the position and dose of irradiation that have been performed up until the time of the shot (writing) to be known for each shot.

[0059] Here, the range of influence of the global misalignment amount is in the range of about several hundred μm to several mm. Therefore, the range of influence of the global misalignment amount is larger than the beam array size (x direction and y direction) of the multi-beam 20, for example, several tens of μm. Therefore, the writing control unit 76 first virtually divides the area on the surface of the sample 101 into a plurality of global mesh areas 11 in a mesh shape of a predetermined size, as shown in FIG. 15. The size of the global mesh area 11 is preferably set to about 1 / 10 of the range of influence of the global misalignment amount, about several tens of μm to several hundreds of μm. For example, if the beam array size is about 80 μm, it is preferably set to about half that, about 40 μm. However, it is not limited to being smaller than the beam array size. It may also be larger than the beam array size.

[0060] In the dose distribution creation step (S112), the dose distribution creation unit 50 calculates the dose distribution of the electron beam irradiated onto a plurality of global mesh regions 11(xi, yi) (processing regions) obtained by dividing the writing region 30 of the sample 101 into a mesh. In other words, the dose distribution creation unit 50 creates the dose distribution of the electron beam irradiated onto a plurality of global mesh regions 11(xi, yi) (processing regions) obtained by dividing the writing region 30 of the sample 101 into a mesh. Specifically, the operation is as follows. The dose distribution creation unit 50 creates, from the writing schedule, a dose distribution indicating the dose of each global mesh region 11 at the time of beam irradiation onto each global mesh region 11(xi, yi) (an example of a position) of the sample 101 when the multibeam 20 is irradiated to write a pattern. For example, for each of the multiple shots of the multibeam 20, a dose distribution is created indicating the dose of each global mesh region 11 irradiated up to that point when the shot at the coordinate (xj, yj) of the sample 101 is completed. i indicates the index of the global mesh region 11. j indicates the index of the shot number. Coordinates (xj, yj) indicate the reference position in the shot. For example, they indicate the coordinates irradiated by the central beam of the multi-beam 20. The dose to each global mesh region 11 is calculated by referring to the dose map and calculating the total incident dose irradiated to each global mesh region 11 (xi, yi).

[0061] In the strain distribution creation step (S114), the strain distribution creation unit 52 uses the irradiation dose distribution to create a strain distribution that defines the amount of strain at each position on the sample 101 caused by irreversible deformation of the sample 101. In other words, the strain distribution creation unit 52 uses the irradiation dose distribution to create a strain distribution that defines the amount of strain caused in the sample 101. Specifically, it operates as follows. The strain distribution creation unit 52 calculates the amount of strain caused in each global mesh region 11 (xi, yi) at each time a beam is irradiated onto each global mesh region 11 (an example of a position) on the sample 101, and creates a strain distribution. For example, for each shot, it calculates the amount of strain caused in each global mesh region 11 (xi, yi) at the time the shot at coordinates (xj, yj) is completed, and creates a strain distribution. Irreversible compressive deformation occurs on the surface of the global mesh region 11 irradiated with the multibeam 20 and in the vicinity thereof (hereinafter referred to as the surface) due to the beam irradiation, and other surfaces of the global mesh region 11 are stretched by stress caused by compressive strain on the surface of the beam-irradiated global mesh region 11. As a result, distortion occurs on the surface of each global mesh region 11 (xi, yi).

[0062] FIG. 17 is a diagram showing an example of the relationship between the reduction ratio of a substrate and the dose amount in the first embodiment. In FIG. 17, the vertical axis represents the reduction ratio, and the horizontal axis represents the dose amount. In the example of FIG. 17, dies a to d were written with variable pattern area density ρ and variable irradiation dose amount D. Then, the amount of distortion (reduction ratio: ΔL / L) in each die was calculated, and the relationship between the amount of distortion (reduction ratio) and ρD (total dose amount per unit area) was calculated. L represents the size of the substrate, and ΔL represents the amount of misalignment. As shown in the example of FIG. 17, it can be seen that the distortion (reduction ratio) increases in proportion to ρD. Therefore, the amount of distortion (reduction ratio) can be obtained using the irradiation amount defined in the irradiation dose distribution. In other words, the sample 101 is irreversibly deformed depending on the irradiation dose distribution of the electron beam.

[0063] Fig. 18 is a diagram showing an example of a model based on the finite element method according to Embodiment 1. In the example of Fig. 18, a 6-inch mask, which is an example of the sample 101, is divided into triangular pyramidal elements. Each triangular pyramid element has four vertices, each of which is connected to a displacement vector u = (u x ,u y ,u z ) three-dimensional displacement information. In other words, one unit element has a total of 4 × 3 = 12 variables. In the relational expression ε = Bu between this displacement vector u (12 × 1) and the strain vector ε (6 × 1), the strain-displacement matrix M1 (6 × 12) of the unit element is expressed as the following equation (1), for example.

[0064]

number

[0065] On the other hand, in the relational expression σ = Dε between the stress vector σ (6 × 1) and the strain vector ε (6 × 1), the material property matrix M2 (6 × 6) of the unit element is expressed as the following equation (2) using the Young's modulus E and Poisson's ratio ν of the quartz substrate.

[0066]

number

[0067] Here, the distortion e of the substrate surface caused by the charged particle beam irradiation dose Q (=ρD) is defined by the following equation (3) using coefficients c0 and c1.

[0068]

number

[0069] If we assume that the shear strain caused by charged particle beam irradiation is zero, the strain vector ε of the unit element can be defined by the following equation (4).

[0070]

number

[0071] The stiffness matrix per unit element is then written as follows:

[0072]

number

[0073] Here, t means the transposed matrix. The above equations are combined for all elements, and the displacement vectors U of all vertices, the global stiffness matrix K, and the equivalent nodal forces f are defined as the following equations (6-1), (6-2), and (6-3).

[0074]

number

[0075] As a result, the following equation (7) is obtained.

[0076]

number

[0077] Finally, the total displacement vector U can be calculated using the following equation (8).

[0078]

number

[0079] The distortion e of each element and the distortion vector ε of equation (4) are calculated by substituting the value of the element of the dose distribution into Q of equation (3). This calculates the distortion amount of each global mesh region 11 at the time of the beam shot to the coordinates (xi, yi), and creates a distortion amount distribution.

[0080] In the deformation distribution creation step (S116), the deformation distribution creation unit 54 uses the strain distribution to calculate the irreversible deformation (Δxi, Δyi, Δzi) occurring in each global mesh region 11 (xi, yi) at each beam irradiation time point, and creates a deformation distribution. For example, for each shot, the unit 54 calculates the irreversible deformation occurring in each global mesh region 11 at the time the shot at the coordinates (xj, yj) is completed, and creates a deformation distribution. For example, by finding f in equation (6-3) using the obtained strain vector ε of each element and solving equation (8), the total displacement vector U, including the displacement vector u of each element at the time the shot at the coordinates (xj, yj) is completed, can be calculated. This makes it possible to calculate the irreversible deformation (Δxi, Δyi, Δzi) occurring in each global mesh region 11 (xi, yi) at the time the shot at the coordinates (xj, yj) is completed.

[0081] In the misalignment distribution creation step (S118), the misalignment distribution calculation unit 56 calculates a misalignment distribution, which defines the amount of misalignment from the designed position of the sample 101 caused by the irreversible deformation of the sample 101 at each position on the sample 101 at the time of irradiating the sample 101 with the electron beam. The sample 101 has a substrate body, a light-reflecting laminate disposed on the substrate body, and a light-absorbing film disposed on the laminate, and the sample 101 undergoes irreversible deformation depending on the distribution of the electron beam dose. In other words, the misalignment distribution calculation unit 56 creates a misalignment distribution, which defines the amount of misalignment from the designed position of the sample 101 caused by the irreversible deformation of the sample 101 at the time of beam irradiation of each global mesh region 11 (an example of a position) of the sample 101 when irradiating the sample 101 with the multibeam 20 to write a pattern. For example, the misalignment distribution is created by calculating the amount of misalignment at a representative position of each global mesh region 11, for example, a central position, and creating the misalignment distribution. The displacement (dxi, dyi) due to the Nth shot at a representative position in each global mesh region 11 (xi, yi) is calculated from the dose distribution due to the first (N-1) shots in that global mesh region. The strain e of each element and the strain vector ε of equation (4) are calculated from the dose distribution and equation (3). Then, f of equation (6-3) is calculated using the obtained strain vector ε of each element, and equation (8) is solved to calculate the total displacement vector U, including the displacement vector u of each element when the corresponding shot at coordinate (xj, yj) is completed. This allows the displacement (dxi, dyi) occurring in each global mesh region 11 (xi, yi) at the time the corresponding shot at coordinate (xj, yj) is completed. As the surface of the substrate body of the sample 101 shrinks in the compression direction, the sample 101 deforms, warping downward and convex, as shown in Figure 5.

[0082] In the determination step (S120), the writing control unit 76 (an example of a determination unit) determines whether misalignment amount distributions have been created for all shots. If misalignment amount distributions have not yet been created for all shots, the process returns to the dose distribution creation step (S112), and the steps from the dose distribution creation step (S112) to the determination step (S120) are repeated while incrementing the shot number to the next number until misalignment amount distributions have been created for all shots. The calculated misalignment amount distributions for each shot are stored in the storage device 142.

[0083] In the above-described corrected layout data generating step (S106), the corrected layout data generating unit 62 corrects the electron beam irradiation position using defect position information indicating the defect position without considering the misalignment amount distribution. In other words, the corrected layout data generating unit 62 corrects the pattern data without considering the misalignment amount distribution. Therefore, by the time the area around the position of the defect 40 is written, the position of the defect 40 has already shifted due to irreversible deformation of the sample 101, as described above. Therefore, when performing correction using the misalignment amount distribution, the correcting unit 58 further corrects the electron beam irradiation position corrected without considering the misalignment amount distribution, taking the misalignment amount distribution into consideration. In other words, the correcting unit 58 further corrects the pattern data corrected without considering the misalignment amount distribution, taking the misalignment amount distribution into consideration. This will be described below.

[0084] As a data correction step (S130), the correction amount calculation unit 57 uses the positional deviation amount distribution to calculate the correction amount of the irradiation position of the electron beam so that the defect occurring in the sample 101 is included in the area where the absorber film 19 remains after writing. The correction unit 58 corrects the pattern data using the misalignment amount distribution so that the defect 40 generated in the sample 101 is included in the region where the absorber film 19 remains after writing. In other words, the correction amount is used to correct the pattern data. Specifically, the operation is as follows. The correction unit 58 corrects the pattern data by, for example, adding the misalignment amount (correction amount) at the time when the location where the defect 40 originally exists is irradiated with the multibeam 20 to the coordinates of the pattern data corrected without taking the misalignment amount distribution into consideration. As a result, in the actual writing process, the pattern of the absorber film 19 can be written on the defect 40 that has moved due to the misalignment of the sample 101.

[0085] After the above pre-processing is completed, the actual drawing process is carried out.

[0086] In the drawing step (S140), the irradiation position is corrected by the correction amount, and a pattern is drawn on the sample 101 with the multi-beam 20 (electron beam). Specifically, the operation is as follows. First, the shot data generation unit 70 creates a new dose map in which the dose amount is defined for each pixel. Here, since the pattern layout data has been corrected, a new dose map is created. The method for creating the dose map is the same as that described above. Next, the shot data generation unit 70 calculates the irradiation time for each pixel 36 using the incident irradiation amount D(x) (dose amount) defined in the dose map. The irradiation time for each pixel 36 can be calculated by dividing the incident irradiation amount D(x) for that pixel by the current density J. When the incident irradiation amount D(x) defined in the dose map is normalized with the reference irradiation amount Dbase set to 1, the irradiation time for each pixel 36 can be calculated by multiplying the incident irradiation amount D(x) by the reference irradiation amount Dbase and dividing the result by the current density J.

[0087] Then, the data processing unit 72 rearranges the obtained irradiation time data for each pixel 36 in shot order and stores it in the storage device 142. The transfer processing unit 74 transfers the irradiation time data to the deflection control circuit 130 in shot order.

[0088] Under the control of the writing control unit 76, the writing mechanism 150 writes a pattern on the sample 101 with the multi-beams 20 (electron beams) whose irradiation positions have been corrected by the correction amount.

[0089] Fig. 19 is a diagram for explaining an example of a multi-beam writing operation in the first embodiment. The example of Fig. 19 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. 19 also shows a writing operation in which the XY stage 105 moves continuously at a speed of, for example, 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. 19 shows a case where each sub-irradiation area 29 is composed of, for example, 4 x 4 pixels.

[0090] In the drawing operation shown in the example of FIG. 19 , for example, while the XY stage 105 moves a distance of two beam pitches in the x direction, the deflector 209 sequentially shifts the irradiation position (pixel 36), and four shots of the multibeam 20 are fired in a shot cycle T to draw (expose) four different pixels 36 in the same sub-irradiation region 29. While drawing (exposing) these four pixels 36, the deflector 208 deflects the entire multibeam 20 collectively to prevent the relative position of the irradiation region 34 with respect to the sample 101 from shifting due to the movement of the XY stage 105, thereby causing the irradiation region 34 to follow the movement of the XY stage 105. In other words, tracking control is performed. In the example of FIG. 19 , the tracking cycle is, for example, the time required for the XY stage 105 to move a distance of two beam pitches in the x direction, but is not limited thereto. It may also be the time required to move a distance greater than two beam pitches, for example, a distance of eight beam pitches or a distance of sixteen beam pitches.

[0091] When one tracking cycle is completed, tracking is reset and the system returns to the previous tracking start position. Since the first pixel row from the left in each sub-irradiation region 29 has been written, after tracking is reset, the deflector 209 first deflects the beam different from the first pixel row in the next tracking cycle to align (shift) the writing position of the beam different from the first pixel row so that writing will begin on an unwritten pixel row in each sub-irradiation region 29, for example, the second pixel row from the left. By repeating this operation during writing of the stripe region 32, the positions of the irradiation regions 34 (34a to 34o) of the multi-beam 20 are sequentially moved, and writing is performed, as shown in the middle diagram of FIG. 15 .

[0092] FIG. 20 is a top view showing an example of the positional relationship between a defect and an absorber film when the defect portion is written in the first embodiment. FIG. 21 is a top view showing an example of the positional relationship between the defect and the absorber film after writing is completed in the first embodiment. In the first embodiment, the pattern layout is corrected taking into consideration that the position of the defect 40 moves with irreversible deformation of the sample 101. As a result, as shown in FIG. 20, when writing the defect, a pattern for the absorber film 19 to remain is written on the defect 40. Then, as the writing process progresses, the deformation of the sample 101 progresses. Accordingly, the positions of the defect 40 and each pattern also move. However, since the defect 40 follows the same movement trajectory as the pattern for the absorber film 19 that has already been written on the defect 40, even after writing is completed, the defect 40 can be included within the region of the pattern for the absorber film 19 to remain, as shown in FIG. 21. Therefore, by performing a development process and an etching process on the sample 101 in this state, the defect 40 can be included within the region of the pattern for the absorber film 19.

[0093] As described above, according to the first embodiment, it is possible to correct defects that are caused to deviate from the absorber pattern region due to irreversible deformation of the EUV mask substrate caused by irradiation with an electron beam.

[0094] Although the embodiments have been described above with reference to specific examples, the present invention is not limited to these specific examples. The processes described in each embodiment may be executed by a computer, and a program for causing a computer to execute such processes may be stored in a non-transitory, tangible readable recording medium such as a magnetic disk device.

[0095] 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.

[0096] In the above example, the misalignment amount distribution is created until all shots are completed, but this is not limiting. It is sufficient for the misalignment amount distribution to be created up to the time when the defect position is written. Therefore, the misalignment amount distribution may be created up to the time when the defect position is written. Furthermore, when there are multiple defects, the misalignment amount when writing each defect may be added to the pattern data for the defect position and its surroundings. Furthermore, although the pattern data is corrected to move the pattern position, correction may be made by the amount of beam deflection, beam array rotation, or magnification.

[0097] In addition, all electron beam writing methods, electron beam writing apparatuses, and programs that include the elements of the present invention and that can be appropriately modified by those skilled in the art are included within the scope of the present invention. [Explanation of symbols]

[0098] 12 LTEM board 13Cr membrane 14 Reference Marks 16 Resist film 17 Multilayer film 18 Cap membrane 19 Absorber membrane 21 Anti-reflection coating 20 Multibeam 22 holes 24 control electrode 25 Passing hole 26 Counter electrode 29 Sub-irradiation area 30 drawing area 31 Blanking aperture array substrate 32 stripe area 33 Support substrate 34 Irradiation area 36 pixels 41 Control circuit 50 Irradiation dose distribution creation unit 52 Strain distribution creation unit 54 Deformation distribution creation section 56 Position deviation distribution creation unit 58 Correction section 60 Defect coordinate conversion unit 62 Corrected layout data generation 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 137 Detection 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 Deflector 209 Deflector 210 Mirror 212 detector 330 Membrane Region

Claims

1. a step of determining a positional deviation distribution, which defines a positional deviation amount from a design position of the sample caused by the irreversible deformation of the sample at each position of the sample at the time of irradiating the charged particle beam on the sample, the positional deviation amount distribution including a substrate body, a laminated body that reflects light and is disposed on the substrate body, and an absorber film that absorbs the light and is disposed on the laminated body; calculating a correction amount for the irradiation position of the charged particle beam using the positional deviation distribution so that the defect generated in the sample is included in a region where the absorber film remains after writing; correcting the irradiation position by the correction amount and drawing a pattern on the sample with a charged particle beam; A charged particle beam writing method comprising:

2. correcting the irradiation position of the charged particle beam using defect position information indicating the defect position without taking the positional deviation distribution into consideration; 2. The charged particle beam writing method according to claim 1, wherein, when correcting using the positional deviation distribution, the irradiation position of the charged particle beam corrected without taking the positional deviation distribution into consideration is further corrected taking the positional deviation distribution into consideration.

3. determining a dose distribution of a charged particle beam irradiated onto a plurality of processing regions obtained by dividing a writing region of the sample into a mesh; generating a strain distribution using the dose distribution to define the strain at each location on the sample caused by irreversible deformation of the sample; 3. The charged particle beam writing method according to claim 1, further comprising:

4. a positional deviation amount distribution calculation unit that creates a positional deviation amount distribution for a sample that has a substrate body, a stacked body that is arranged on the substrate body and reflects EUV light, and an absorber film that is arranged on the stacked body and absorbs the EUV light, the sample irreversibly deforming depending on an irradiation dose distribution of the charged particle beam, the positional deviation amount distribution defining a positional deviation amount from a design position of the sample that occurs due to the irreversible deformation of the sample at each position of the sample at the time of irradiating the charged particle beam with the charged particle beam; a correction amount calculation unit that calculates a correction amount of the irradiation position of the charged particle beam using the positional deviation amount distribution so that a defect generated in the sample is included in a region where the absorber film remains after writing; a drawing mechanism that draws a pattern on the sample with the charged particle beam whose irradiation position has been corrected by the correction amount; A charged particle beam drawing apparatus comprising:

5. a process of creating a positional deviation distribution of a sample that has a substrate body, a stacked body that reflects EUV light and is disposed on the substrate body, and an absorber film that absorbs the EUV light and is disposed on the stacked body, the sample irreversibly deforming depending on an irradiation dose distribution of a charged particle beam, the process defining a positional deviation amount from a design position of the sample that occurs due to the irreversible deformation of the sample at each position of the sample at the time of irradiating the charged particle beam with the charged particle beam; a process of storing the generated positional deviation amount distribution in a storage device; a process of reading out the positional deviation amount distribution from the storage device, and calculating and outputting a correction amount for the irradiation position of the charged particle beam using the positional deviation amount distribution so that a defect occurring in the sample is included in a region where the absorber film remains after writing; A program that causes a computer to execute the following.

Images