Mark position measuring device and mark position measuring method

Abstract

This mark position measuring device according to one embodiment of the present invention comprises: a height position distribution acquisition circuit that acquires a height position distribution of the surface of a sample on the basis of a result obtained by a sensor in a state in which the height position of the sample is controlled so as to reach a predetermined height position; a mark position calculating circuit that calculates the position of a plurality of marks using changes in signals due to the state of the surface of the sample of the mark obtained by the sensor by scanning the plurality of marks using laser light so as to intersect the plurality of marks in a state in which the height position of the sample is controlled to be at a prescribed height position; a position displacement amount calculating circuit that calculates the amount of position displacement from the position of the mark calculated using the incidence angle of the laser light and the surface height position of the sample at the plurality of mark positions obtained from the acquired height position distribution of the surface of the sample; and a correction circuit that corrects the position of the mark calculated using the corresponding amount of position displacement among the plurality of calculated position displacement amounts with respect to the plurality of marks.

Description

Mark position measuring device and mark position measuring method

[0001] This application claims priority from JP2023-195650 (application number) filed in Japan on November 17, 2023. The entire contents of JP2023-195650 are incorporated herein by reference.

[0002] The present invention relates to a mark position measurement apparatus and a mark position measurement method, and relates to, for example, a technique for measuring the position of an alignment mark on a sample to be written.

[0003] Lithography technology, which is responsible for the advancement of miniaturization of semiconductor devices, is an extremely important process in semiconductor manufacturing, as it is the only one that generates patterns. In recent years, with the increasing integration density of LSIs, the circuit line width required for semiconductor devices has become finer year by year. Here, electron beam (EB) lithography technology has inherently excellent resolution, and lithography is performed using an electron beam to draw on wafers, etc.

[0004] For example, there is a lithography system that uses multiple beams. Compared to lithography using a single electron beam, the use of 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.

[0005] In electron beam lithography including multi-beam lithography, when the substrate to be lithographed is placed on the stage, alignment marks formed on the substrate are detected by the electron beam, and the lithography area is aligned based on the detected alignment marks.

[0006] Modern alignment marks are formed with finer line widths than conventional alignment marks. The electron yield when the mark is irradiated with an electron beam is low, making it difficult to obtain contrast. This results in a poor signal-to-noise ratio, making it difficult to find the alignment mark on the substrate. To address this issue, increasing the electron beam dose to obtain contrast has been considered. However, this method poses the problem of resist scattering and contaminating the chamber when a high-dose electron beam is irradiated over a wide area.

[0007] Here, a method is disclosed in which a cross mark with a reflectance different from that of the surrounding area is formed on the surface of a sample, the cross mark is scanned with a z-sensor, and the position of the cross mark is measured based on the change in the amount of received light. The z-sensor also measures the height position of the cross mark, and if the height position of the cross mark deviates from the normal height, the error in the measured position of the cross mark resulting from the height deviation is corrected (see, for example, Patent Document 1). As such, the accuracy of the mark position measured by the z-sensor may be insufficient. Furthermore, this method requires a separate step of measuring the height position of the mark to confirm whether or not there is a position deviation and, if there is a position deviation, to correct it.

[0008] JP 2010-074110 A

[0009] One aspect of the present invention provides an apparatus and method capable of measuring the positions of multiple marks formed on a sample with high accuracy.

[0010] a sensor having an irradiator that irradiates the sample with laser light and a photodetector that receives light reflected from the sample due to the laser light irradiation and outputs a signal of the height position at the irradiation position on the surface of the sample; a height position distribution acquisition circuit that acquires a height position distribution on the surface of the sample based on the results obtained by the sensor while the height position of the sample is controlled to be a predetermined height position; a mark position calculation circuit that calculates positions of the multiple marks using a change in a signal due to the state of the surface of the sample of the marks obtained by scanning multiple marks with the laser light so that the marks intersect with the multiple marks while the height position of the sample is controlled to be the predetermined height position; a positional deviation calculation circuit that calculates a positional deviation amount from the calculated position of the mark using the incident angle of the laser light and the surface height positions of the sample at the multiple mark positions obtained from the acquired height position distribution on the surface of the sample; and a correction circuit that corrects the calculated position of the mark by using a corresponding positional deviation amount from the calculated position of the multiple marks.

[0011] Another aspect of the mark position measurement device of the present invention is characterized by comprising: a movable stage for placing a sample having a plurality of marks formed thereon; a sensor having an irradiator for irradiating the sample with laser light and a photodetector for receiving light reflected from the sample due to the irradiation of the laser light and outputting a signal of a height position at the irradiation position on the surface of the sample; a height position calculation circuit for calculating a first height position using height position information obtained by the sensor at each position where the plurality of marks are assumed to be present; a mark position calculation circuit for calculating positions of the plurality of marks using a change in a signal resulting from the state of the surface of the sample of the marks obtained by the sensor by scanning the plurality of marks with laser light so that the plurality of marks intersect with the plurality of marks, while controlling the height position of the sample so that the first height position becomes a reference height position; and a control circuit for controlling the height position of the sample so that a second height position set for drawing becomes the reference height position, in order to draw a pattern on the sample using a charged particle beam.

[0012] A mark position measurement method according to one aspect of the present invention includes the steps of: measuring the height position of the surface of the sample using a sensor having an irradiator that irradiates the sample with laser light and a light receiver that receives light reflected from the sample due to the irradiation of the laser light and outputs a signal of the height position at the irradiation position on the surface of the sample, while the height position of the sample is controlled to be a predetermined height position; obtaining a height position distribution of the surface of the sample based on the results measured by the sensor; calculating positions of the multiple marks using a change in a signal resulting from the state of the surface of the sample of the marks obtained by scanning multiple marks with the laser light so that the multiple marks intersect with each other, while the height position of the sample is controlled to be a predetermined height position; calculating a positional deviation from the calculated position of the mark using the angle of incidence of the laser light and the surface height positions of the sample at the multiple mark positions obtained from the obtained distribution of height positions of the sample surface; and correcting the calculated position of the mark using a corresponding positional deviation amount among the multiple calculated positional deviation amounts for the multiple marks, and outputting the corrected position of the mark.

[0013] Another aspect of the mark position measurement method of the present invention is characterized in that it includes: measuring height information at each position where a plurality of marks are expected to be present on a sample placed on a stage and having a plurality of marks formed thereon, using a sensor having an irradiator that irradiates the sample with laser light and a photodetector that receives light reflected from the sample due to the irradiation of the laser light and outputs a signal of the height position at the irradiation position on the surface of the sample; calculating a first height position using the height position information obtained by the sensor at each position where a plurality of marks are expected to be present; calculating and outputting positions of the plurality of marks using a signal change due to the state of the surface of the sample of the marks obtained by scanning the plurality of marks with the laser light so that the height position of the sample is controlled so that the first height position becomes a reference height position; and controlling the height position of the sample so that a second height position set for drawing becomes the reference height position in order to draw a pattern on the sample using a charged particle beam.

[0014] According to one aspect of the present invention, it is possible to measure with high accuracy the positions of multiple marks formed on a sample, the concave and convex surfaces of which are made of the same material. Furthermore, when correcting the mark positions, the correction can be made using information obtained by the drawing operation without having to take the trouble of measuring the height position of each mark.

[0015] 1 is a conceptual diagram showing the configuration of a writing apparatus according to the first embodiment. FIG. 2 is a conceptual diagram showing the configuration of a shaping aperture array substrate according to the first embodiment. FIG. 3 is a cross-sectional view showing the configuration of a blanking aperture array mechanism according to the first embodiment. FIG. 4 is a top view showing an example of the configuration of a sample according to the first embodiment. FIG. 5 is a cross-sectional view showing an example of the configuration of an alignment mark according to the first embodiment. FIG. 6 is a cross-sectional view showing another example of the configuration of an alignment mark according to the first embodiment. FIG. 7 is a diagram for explaining an error when measuring a mark position with a z sensor according to the first embodiment. FIG. 8 is a flowchart showing an example of main steps of a writing method according to the first embodiment. FIG. 9 is a diagram for explaining a stage mechanism and a writing height position according to the first embodiment. FIG. 10 is a diagram for explaining an example of a height measurement position within a sample surface according to the first embodiment. FIG. 11 is a diagram for explaining a method of mark rough search according to the first embodiment. FIG. 12 is a diagram for explaining the measurement principle of the z sensor according to the first embodiment. FIG. 13 is a diagram showing an example of the intensity distribution of laser light used in the z sensor according to the first embodiment. FIG. 14 is a cross-sectional view showing an example of the state of irradiated light when an alignment mark is scanned with the z sensor according to the first embodiment. FIG. 15 is a cross-sectional view showing an example of the state of reflected light when an alignment mark is scanned with the z sensor according to the first embodiment. FIG. 16 is a diagram showing an example of the height position distribution of a concave-convex mark according to the first embodiment. FIG. 1 is a diagram showing an example of a height position distribution in embodiment 1. FIG. 2 is a conceptual diagram for explaining an example of a writing operation in embodiment 1. FIG. 3 is a diagram showing an example of a multi-beam irradiation area and a writing target pixel in embodiment 1. FIG. 4 is a diagram for explaining an example of a multi-beam writing operation in embodiment 1. FIG. 5 is a diagram showing an example of a surface height position of a sample in the vicinity of a mark position including a mark position in embodiment 2. FIG. 6 is a flowchart showing an example of main steps of a writing method in embodiment 3. FIG. 7 is a diagram for explaining a stage mechanism and a height position for mark search in embodiment 3.

[0016] 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, although a lithography apparatus using a multi-beam will be described below, the present invention is not limited to this. A lithography apparatus using a single beam may also be used. For example, the present invention can be applied to a variable beam shaping (VSB) type lithography apparatus.

[0017] [First Embodiment] Fig. 1 is a conceptual diagram showing the configuration of a lithography apparatus according to a 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, an electrostatic lens 212, and a detector 226 are arranged.

[0018] A stage 105 is placed in the patterning chamber 103. A sample 101, such as a mask, which will be the patterned substrate during patterning (exposure) is placed on the stage 105. The sample 101 includes an exposure mask used in manufacturing a semiconductor device, or a semiconductor substrate (silicon wafer) on which a semiconductor device is manufactured. The sample 101 also includes a mask blank coated with resist and on which nothing is yet patterned. A plurality of alignment marks (concave and concave marks), the concave and convex surfaces of which are made of the same material, are formed on the sample 101, as will be described later.

[0019] Furthermore, a mirror 210 for measuring the position of the stage 105 is disposed on the stage 105. Furthermore, a marking stage 106 is disposed on the stage 105. A pattern such as a cross mark is formed on the surface of the marking stage 106. The surface height of the marking stage 106 is used as a reference height.

[0020] A z-sensor 220 (an example of a sensor) is also disposed above the pattern writing chamber 103. The z-sensor 220 includes an irradiator 222 that generates, for example, a visible laser beam and a photodetector 224 that receives light reflected from the target object upon irradiation with the laser beam. The irradiator 222 obliquely irradiates the surface of the sample 101 placed on the stage 105 within the pattern writing chamber 103 with the laser beam. The irradiator 222 thus irradiates the sample 101 with the laser beam. The laser beam generated by the irradiator 222 has a normal light intensity distribution. The laser beam generated by the irradiator 222 has a diameter larger than the width of the alignment mark formed on the sample 101. This is due to the beam diameter at the time of emission and the optical elements that guide the beam, as well as the large influence of the beam spreading in the direction of incidence due to oblique incidence on the sample. For example, a laser beam with a diameter of 10 to 300 μm on the surface of the sample 101 is used. For example, it is preferable to use a laser beam with a diameter of about 200 μm on the surface of the sample 101. The photoreceiver 224 receives the light reflected from the sample 101 when the laser beam is irradiated, and outputs a signal representing the height position at the irradiation position on the surface of the sample 101. For example, an optical position sensor is used as the photoreceiver 224. The photoreceiver 224 receives the reflected light, measures the height position of the surface of the sample 101 from the deviation of the light-receiving position on the light-receiving surface, and outputs the signal.

[0021] 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 detection circuit 135, a lens control circuit 136, a stage control mechanism 138, a stage position measurement device 139, and storage devices 140 and 142 such as magnetic disk drives. The control computer 110, the memory 112, the deflection control circuit 130, the detection circuit 135, the lens control circuit 136, the stage control mechanism 138, the stage position measurement device 139, and storage devices 140 and 142 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 composed of 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, reduction lens 205, and objective lens 207, are controlled by a lens control circuit 136. The detector 226 is connected to a detection circuit 135. The electrostatic lens 212 is controlled by an electrostatic lens control circuit (not shown).

[0022] The position of the 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 stage 105 based on the principle of laser interferometry.

[0023] The control computer 110 includes a height position calculation unit 50, a height position distribution acquisition unit 52, a first height position distribution calculation unit 53, a mark area specification unit 54, a second height position distribution calculation unit 56, a first mark position calculation unit 58, a positional deviation amount calculation unit 60, a correction unit 62, a second mark position calculation unit 68, a shot data generation unit 70, a data processing unit 72, a transfer processing unit 74, and a control unit 76. Each of the "units" such as the height position calculation unit 50, the height position distribution acquisition unit 52, the first height position distribution calculation unit 53, the mark area specification unit 54, the second height position distribution calculation unit 56, the first mark position calculation unit 58, a positional deviation amount calculation unit 60, the correction unit 62, the second mark position calculation unit 68, the shot data generation unit 70, the data processing unit 72, the transfer processing unit 74, and the 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 different processing circuits (separate processing circuits). Information input to and output from the height position calculation unit 50, the height position distribution acquisition unit 52, the first height position distribution calculation unit 53, the mark area specification unit 54, the second height position distribution calculation unit 56, the first mark position calculation unit 58, the position deviation amount calculation unit 60, the correction unit 62, the second mark position calculation unit 68, the shot data generation unit 70, the data processing unit 72, the transfer processing unit 74, and the control unit 76, as well as information being calculated, are stored in memory 112 each time.

[0024] The drawing operation of the drawing apparatus 100 is controlled by a 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.

[0025] Furthermore, drawing data (chip data) is input from outside the drawing device 100 and stored in the storage device 140. The chip data defines information on a plurality of figure patterns that make up the chip pattern. Specifically, for each figure pattern, for example, the coordinates of each vertex are defined in the order in which the figure is formed. Alternatively, for each figure pattern, for example, a figure code, coordinates, size, etc. are defined.

[0026] 1 shows the configuration necessary for explaining the first embodiment. The drawing device 100 may also include other configurations that are normally required.

[0027] FIG. 2 is a conceptual diagram showing the configuration of a shaping aperture array substrate in embodiment 1. In FIG. 2 , holes (openings) 22 are formed in a matrix of p columns (y direction) x 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, for example, a case where 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 multibeam 20 is formed when a portion of the electron beam 200 passes through each of these multiple holes 22. 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.

[0028] FIG. 3 is a cross-sectional view showing the configuration of the blanking aperture array mechanism according to the first embodiment. As shown in FIG. 3 , the blanking aperture array mechanism 204 includes a blanking aperture array substrate 31, which is made of a semiconductor substrate such as silicon, and is disposed on a support base 33. In a central membrane region 330 of the blanking aperture array substrate 31, passage holes 25 (openings) for passing 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 . Furthermore, 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.

[0029] 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. An input (IN) of the CMOS inverter circuit receives, as a control signal, 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. 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). 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 blocked by the limiting aperture substrate 206, thereby controlling the beam to be turned OFF. 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, there is no potential difference with the ground potential of the opposing electrode 26, and the corresponding beam is not deflected, so that the beam is controlled to be ON by passing through the limiting aperture substrate 206. Blanking control is performed by this deflection.

[0030] 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 almost perpendicularly by an illumination lens 202 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).

[0031] The multi-beams 20 that pass through the blanking aperture array mechanism 204 are reduced by a reduction lens 205 and travel toward a central hole formed in a 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 beam is turned on until when the beam is 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 stage 105 is moving continuously, tracking control is performed by the deflector 208 so that the beam irradiation position follows the movement of the 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.

[0032] In electron beam lithography, including multi-beam lithography and VSB single-beam lithography, alignment marks formed on the sample are detected when the target substrate is placed on the stage. The detected alignment marks are then used as a reference to align the lithography area. Modern alignment marks are formed with finer line widths than conventional alignment marks.

[0033] Fig. 4 is a top view showing an example of the configuration of a sample in embodiment 1. In Fig. 4, a writing region 30 for writing a desired pattern in the center of the sample 101 and alignment mark regions 10 are set outside the writing region 30, for example, at each of the four corners of the sample 101. In the example of Fig. 4, four alignment mark regions 10 are set. Within each alignment mark region 10, a large mark 12 (one example of an alignment mark and a concave-convex mark) having a large mark size and a small mark 14 (another example of an alignment mark and a concave-convex mark) having a small mark size are formed.

[0034] The example in Figure 4 shows a case where a large mark 12 and a small mark 14 are formed at diagonal positions within an alignment mark region 10 that is, for example, 11,000 µm square. For example, a cross pattern is used for both the large mark 12 and the small mark 14. Both the large mark 12 and the small mark 14 are formed as concave-convex marks with a concave-convex structure in which the concave and convex surfaces are made of the same material. The cross pattern forms a concave portion, and the area around the cross pattern forms a convex portion. Thus, such concave-convex marks are formed on the sample 101.

[0035] The large mark 12 is formed with a large mark size of about 4000 μm and is used as a temporary alignment mark, for example, to search for the alignment mark region 10 from a wide area on the surface of the sample 101. The small mark 14 is formed with a small mark size of about 400 μm and is used as an alignment mark that serves as a positional reference. The large mark 12 may also be used as an alignment mark that serves as a positional reference. The small mark 14 may also be used as a mark that is used to search for the alignment mark region 10 from a wide area on the surface of the sample 101.

[0036] The large mark 12 and the small mark 14 use patterns with the same line width, for example. Both the large mark 12 and the small mark 14 are formed by a cross pattern that combines a line pattern extending in the x direction, with the recessed portion having a line width of 2 to 200 μm, for example, 4 to 5 μm, and a line pattern extending in the y direction, with the same line width as the line pattern extending in the x direction. The specific configuration will be described below.

[0037] FIG. 5 is a cross-sectional view showing an example of the configuration of an alignment mark in the first embodiment. The example in FIG. 5 shows a case where the exposure mask is used as the sample 101. In the sample 101, as shown in FIG. 5, a light-shielding film 82 made of chromium (Cr) or the like is formed on a glass substrate 80. Then, recesses are formed in the light-shielding film 82, and the recessed portions are used as the line width of the alignment mark. Therefore, the surfaces of the recessed and protruding portions are made of the same light-shielding film 82. In this manner, the small marks 14 that become alignment marks are formed with a concave-convex structure made of the same material. Similarly, the large mark 12 is formed with a concave-convex structure made of the same material. Then, the sample 101 (mask) on which these marks are formed is coated with resist and transported into the writing apparatus 100, where mark measurement is performed.

[0038] FIG. 6 is a cross-sectional view showing another example of the alignment mark configuration in the first embodiment. The example in FIG. 6 shows a case where the sample 101 is an EUV exposure mask. In the sample 101, a multilayer film 86, for example, made of molybdenum (Mo) and silicon (Si) stacked in multiple layers, is formed on a low-thermal expansion glass substrate 84. A recess is formed in a portion of the multilayer film 86, and an absorber film 88 (anti-reflection film) mainly composed of, for example, Cr or tantalum (Ta) is formed on the multilayer film 86, including the recess. The recessed portion of the absorber film 88 formed on the recessed portion of the multilayer film 86 is used as the line width of the alignment mark. Therefore, the surfaces of the recessed and protruding portions of the absorber film 88 are the same. In this way, the small marks 14 that serve as alignment marks are formed with a concave-convex structure made of the same material. The large mark 12 is also formed with a concave-convex structure made of the same material. The sample 101 (mask) on which these marks are formed is coated with resist and transported into the writing apparatus 100, where mark measurement is performed.

[0039] 5 and 6 show an example in which the mark portion is concave, and the following processing is explained as concave signal processing accordingly. However, there may be cases in which the mark portion is convex. In that case, the series of processing is the same, except that the output signal becomes convex.

[0040] Conventionally, alignment marks on the sample surface 101 are searched for using an electron beam, and their positions are measured using the electron beam. However, for marks with a concave-convex structure made of the same material, the difference in electron yield when scanning the mark with the electron beam is small, making it difficult to obtain contrast. As a result, there is a problem of a low S / N ratio and difficulty in finding alignment marks on the sample 101. To address this issue, increasing the electron beam dose has been considered to obtain contrast. However, this method involves irradiating the resist with a high dose of electron beam over a wide area, causing the resist to scatter and contaminate the chamber. Therefore, in the first embodiment, the z sensor 220 is used to search for alignment marks over a wide area on the sample 101 surface using laser light that does not cause resist scattering or is negligible, and the center position is measured as the mark position. Note that the mark position may be measured with even higher accuracy depending on the required accuracy. In such a case, after the mark position is identified using laser light, the center position of the alignment mark is measured using an electron beam with higher accuracy than the measurement using laser light.

[0041] FIG. 7 is a diagram for explaining errors when measuring a mark position with the z sensor in the first embodiment. As shown in FIG. 7, the z sensor 220 causes laser light to be obliquely incident on the surface of the sample 101. In mark measurement with the z sensor 220, the projection light is irradiated onto the surface of the sample 101 at a high angle of incidence θ, for example, 80 degrees or more. Therefore, a height deviation becomes a lateral deviation error and is included in the measurement result. Therefore, if the height position of the sample 101 deviates, the irradiation position of the laser light also deviates. For example, if the height position of the sample surface deviates by Δh with respect to the incidence angle θ of the laser light on the z sensor 220, the positional deviation amount Δr of the irradiation position can be defined by the following equation (1): (1) Δr = tan θ Δh

[0042] 7 and Equation (1), the direction of irradiation of the laser light from the z sensor 220 when projected onto the sample surface is the r direction. Therefore, if the r direction projected onto the sample surface along which the laser light from the z sensor 220 travels is, for example, the x direction in the drawing data, then Δr = Δx. Similarly, if the r direction projected onto the sample surface along which the laser light from the z sensor 220 travels is, for example, the y direction in the drawing data, then Δr = Δy. The r direction is not limited to the x direction or y direction in the drawing data. For example, the r direction may be a direction at an intermediate angle between the x direction and the y direction in the drawing data (for example, a direction shifted in phase by 45 degrees from the x axis).

[0043] Therefore, as will be described later, when measuring the position of the large mark 12 (small mark 14) using the z sensor 220, if the height position of the sample surface deviates by Δh, the actual position of the large mark 12 (small mark 14) will deviate in the r direction from the measured position by a positional deviation amount Δr. For example, if the height deviates by 1 μm at an incident angle of 80°, the mark signal will be detected at a position deviated in the r direction by Δr = tan 80° × 1 [μm] = 5.67 μm. For this reason, in the first embodiment, such an error is corrected. However, if a separate height measurement is performed to correct the mark position, additional process time is required, lengthening the writing time. Therefore, in the first embodiment, rather than measuring the height position of the mark specifically to correct the mark position, data obtained for use in a different application, such as the writing process, is utilized.

[0044] 8 is a flowchart showing an example of main steps of the writing method according to the first embodiment. In FIG. 8, the writing method according to the first embodiment performs a series of steps, including a writing height position measurement / calculation step (S102), a writing height position setting step (S104), a writing height position distribution acquisition step (S106), a mark search step (S110), a mark rough search step (S112), a mark position calculation step (S114), a position deviation amount calculation step (S116), a correction step (S118), a mark scanning step (S126), a mark position calculation (fine detection) step (S128), a shot data generation step (S130), a data processing step (S132), and a writing step (S140). Note that the mark scanning step (S126) and the mark position calculation (fine detection) step (S128) may be omitted depending on the required measurement accuracy of the mark position. In such a case, the correction step (S118) is followed by the shot data generation step (S130).

[0045] In the writing height position measurement / calculation step (S102), the z sensor 220 is used to measure height positions at a plurality of preset positions on the sample 101. In S102, if a measurement equivalent to S106 (described later) is performed to simultaneously acquire the height position distribution on the sample surface, S106 may be omitted.

[0046] FIG. 9 is a diagram illustrating the stage mechanism and the height position for writing in the first embodiment. In FIG. 9 , the stage 105 includes an XY stage 107 and a Z stage 108. In the example of FIG. 9 , the Z stage 108 is disposed on the XY stage 107. The mark stage 106 is disposed on the XY stage 107 in parallel with the Z stage 108. The sample 101 is supported by multiple pins 211 on the Z stage 108. For example, it is supported at three points. If the change in the height direction on the surface of the sample 101 does not affect performance, the value measured in S102 is used as the surface height. However, the outer periphery of the sample 101 is supported by multiple pins 211. Therefore, as shown in FIG. 9 , deflection due to its own weight, height distribution, and tilt may occur. Therefore, in S102, multiple points on the surface of the sample 101 are measured, and the mask surface height is adjusted so that the writing area falls within a focus range (where focus adjustment is possible) that satisfies writing performance. For example, if the sample surface height distribution has a highest height Z1 and a lowest height Z2, the midpoint (Z0) is set. Z0 is set to an appropriate position between Z1 and Z2 depending on the characteristics of the focus function and the arrangement of patterns that are more sensitive to focus.

[0047] In the drawing height position setting step (S104), the Z stage 108 is driven to control the height position of the sample 101 so that the calculated height position Z0 becomes the reference height position. For example, the surface height position of the mark stage 106 is set as the reference position, and the Z stage 108 moves the sample 101 in the z direction so that the calculated height position Z0 coincides with this reference height position. This allows the sample surface height to be adjusted in the drawing step (S140).

[0048] In the drawing height position distribution acquisition step (S106), the height position distribution acquisition unit 52 acquires the height position distribution of the surface of the sample based on the results obtained by the sensor, while the height position of the sample is controlled to be at a predetermined height position. In other words, the height position distribution acquisition unit 52 acquires the height position distribution of the surface of the sample 101 based on the results obtained by the z sensor 220, while the height position of the sample 101 is controlled so that the height position Z0 set for drawing becomes the reference height position. Specifically, it operates as follows.

[0049] 10 is a diagram showing an example of height measurement positions within the sample surface in embodiment 1. With the writing height position Z0 at the reference height position, the z sensor 220 is used to measure height positions at a plurality of preset positions on the sample 101. In the example of FIG. 10 , height positions are measured at k×k locations, for example, 8×8 locations, within the writing region 30 of the sample 101.

[0050] The z sensor 220 outputs height position information measured at a plurality of k × k positions on the surface of the sample 101. The height position distribution acquisition unit 52 calculates the height position distribution for drawing on the surface of the sample 101 using a predetermined calculation formula, using the height position information (coordinates of each position and the height difference from a reference height) of the plurality of k × k positions on the surface of the sample 101. For example, fitting is performed using a polynomial (e.g., a cubic polynomial). The acquired information on the height position distribution on the surface of the sample 101 for drawing is stored in the storage device 142.

[0051] In the above example, a case has been described in which height positions at k×k locations are measured and then a height position distribution for drawing on the surface of the sample 101 is calculated using a predetermined calculation formula, but the present invention is not limited to this. For example, for each stripe region 32, the z sensor 220 may be used to scan the stripe region 32, the height at each position may be measured, and the height position distribution obtained from this may be acquired.

[0052] In the mark search step (S110), the z sensor 220 is used to search for the large mark 12 from a wide area on the sample 101. The position of the alignment mark area 10 on the sample 101 is determined by design. However, the relative positional relationship between the sample 101 and the stage 105, which is carried into the writing chamber 103 and placed on the stage 105, does not necessarily match the designed positional relationship. For example, the sample 101 may be misaligned. As a result, the large mark 12 may not be located where it should be in the design. Therefore, the actual large mark 12 is searched for based on the designed position of the large mark 12. Specifically, the stage 105 is moved to a designed position where the large mark 12 is irradiated with laser light from the z sensor 220. Using this position as a reference, the stage 105 is moved by a sufficient distance from the reference position, for example, in the −x direction, so that the irradiation position of the laser light is located at a predetermined pitch, for example, in the −x direction. This allows the actual large mark 12 to be located, and the height position of the sample 101 to be measured at multiple measurement positions. This allows the height position to be measured relatively at multiple measurement positions in the x direction on the sample surface. The measured height position information is output to the control computer 110.

[0053] The first height position distribution calculation unit 53 inputs the measured height position information and calculates the height position distribution. Then, the mark area identification unit 54 searches for a position where the height position is lower than the surrounding area and identifies such a position as the alignment mark area 10. The height position distribution obtained from the z sensor 220 will be described in detail later.

[0054] In the mark rough search step (S112), while moving the sample 101 placed on the stage 105, the z sensor 220 is used to measure the height position distribution on the surface of the sample 101, which is obtained by scanning the small marks 14 (or large marks 12) (concave and convex marks) in the specified alignment mark region 10 with laser light so as to intersect. If there are alignment mark regions 10 at each of the four corners of the sample 101, a mark rough search step (S104) is performed on each of the small marks 14 (or large marks 12) (concave and convex marks) in the alignment mark region 10 specified at the four corners.

[0055] FIG. 11 is a diagram illustrating a method for performing a mark rough search in the first embodiment. As shown in FIG. 11 , the small mark 14 is formed by crossing a line pattern extending in the x direction with a line pattern extending in the y direction. Therefore, the position of the line pattern of the small mark 14 is measured on the paper surface of FIG. 11 . The direction perpendicular to the direction in which the line pattern extends is set as the measurement direction, and scanning is performed in the measurement direction. For example, scanning is performed over a distance twice the beam diameter of the laser light. The example in FIG. 11 illustrates a case in which a line pattern extending in the y direction is scanned in the x direction, and a case in which a line pattern extending in the x direction is scanned in the y direction. Specifically, by moving the stage 105, the irradiation position of the laser light from the z sensor 220 on the surface of the sample 101 is sequentially moved to multiple measurement positions. If there is a large amount of noise signal due to location dependency, etc., the noise component is averaged or canceled out by repeatedly calculating and averaging the noise at multiple locations in a non-measurement direction perpendicular to the measurement direction. For example, in the measurement of the line pattern extending in the y direction described above, the process of scanning and measuring in the x direction, then stepping in the y direction, and then scanning and measuring in the x direction is repeated. In the mark rough search step (S112), when scanning in the x and y directions, it is preferable to scan in a scanning range larger than the size of the target mark (here, for example, small mark 14), as shown in Figure 11.

[0056] 12 is a diagram for explaining the measurement principle of the z sensor in embodiment 1. The light receiving position 1, which is the center of gravity of reflected light 9 when laser light 8 is reflected at height Z1 and received by the light receiver, differs from light receiving position 2, which is the center of gravity of reflected light 9 when the same laser light 8 is reflected at height Z2 and received by the light receiver. The height position on the surface of sample 101 can be calculated by multiplying the light receiving position by a height conversion coefficient.

[0057] 13 is a diagram showing an example of the intensity distribution of the laser light used in the z sensor according to the first embodiment. As shown in FIG. 13, the laser light used in the z sensor 220 according to the first embodiment has a light intensity distribution that is a normal distribution. In other words, the intensity of the laser light is greater toward the center of the beam and decreases radially outward. For example, visible light is preferably used as the laser light.

[0058] FIG. 14 is a cross-sectional view showing an example of the state of irradiated light when an alignment mark is scanned with the z sensor according to the first embodiment. FIG. 15 is a cross-sectional view showing an example of the state of reflected light when an alignment mark is scanned with the z sensor according to the first embodiment. Due to the miniaturization of the line widths of the large marks 12 and the small marks 14, the laser light 8 used in the z sensor 220 has a diameter larger than the width (line width) of the large marks 12 (concave and convex marks) and the small marks 14 (concave and convex marks). The sample 101 surface is irradiated with a beam diameter of, for example, 10 μm to 300 μm. The sample 101 surface is irradiated with a beam diameter of, for example, 200 μm. The irradiator 222 of the z sensor 220 causes the laser light 8 to be obliquely incident on the surface of the sample 101. Therefore, as shown in FIG. 14 , a wide area of ​​width S, including the small marks 14 (or large marks 12) with line width W, is simultaneously irradiated with the laser light 8. The photodetector 224 receives the reflected light 9 from the sample 101 due to the irradiation of the laser light 8. At this time, the photodetector 224 simultaneously receives the reflected light 9 from a wide region of width S including the small mark 14 (or large mark 12) with line width W, as shown in FIG. 15. As shown in FIG. 15, the reflected light 9 contains a portion of light (dotted line) that carries height information about the bottom surfaces of the recesses of the small mark 14 (or large mark 12) (concave and convex mark). The photodetector 224 then outputs height information about the surface of the sample 101.

[0059] In the mark position calculation step (S114), the second height position distribution calculation unit 56 inputs the measured height position information and calculates the height position distribution. The height position distribution on the surface of the sample 101 is obtained by scanning the small mark 14 (or large mark 12) (concave and convex mark) with the laser light 8 so that it intersects with the small mark 14 (or large mark 12) (as shown in FIG. 11 ). In the mark rough search step (S112), the position of the line pattern is measured at each position above, below, left, and right of the small mark 14 (or large mark 12) on the paper surface of FIG. 11 . Since the measurement is repeated in multiple stages while shifting the position in the direction in which the line pattern extends (non-measurement direction), multi-stage height position information is output from the photodetector 224. Therefore, the height position calculation unit 50 averages the measurement results measured in multiple stages in the non-measurement direction. This reduces the effects of differences in mark locations and noise during measurement.

[0060] If small marks 14 (or large marks 12) are provided at the four corners of the sample 101, the height position distribution is calculated in the same manner for each small mark 14 (or large mark 12) (concave and convex marks).

[0061] 16 is a diagram showing an example of the height position distribution of the uneven mark in embodiment 1. In FIG. 16, the vertical axis indicates the height position, and the horizontal axis indicates the position on the sample (e.g., the position in the x direction). In embodiment 1, the laser light 8 used in the z sensor 220 has a light intensity distribution of a normal distribution. If the laser light 8 has a light intensity distribution, then the reflected light 9 will also have a light intensity distribution according to the light intensity of the original laser light 8. The height position is calculated by multiplying the light reception position of the center of gravity of the received reflected light 9 by a height conversion coefficient.

[0062] The center of gravity position of the reflected light 9 is affected by the light intensity at each light receiving position on the light receiving surface of the light receiver 224. Therefore, the change in the center of gravity position can be greater when height information of the bottom of the concave surface is acquired from a portion with high light intensity than when it is acquired from a portion with low light intensity. As a result, as shown in FIG. 16 , when a small mark 14 (or a large mark 12) with a line width W is located within the beam diameter of the laser light 8, the height position changes depending on the position of the light intensity distribution at which the small mark 14 (or the large mark 12) with a line width W is irradiated. As shown in FIG. 16 , height position A shows the case where the small mark 14 (or the large mark 12) is irradiated at the peak position (maximum light intensity) of the light intensity of the laser light 8. Height position B shows the case where the small mark 14 (or the large mark 12) is irradiated at a light intensity position, for example, approximately 20% of the peak position (maximum light intensity) of the light intensity of the laser light 8. As shown in FIG. 16 , the height position of the concave surface changes more significantly compared to the height position of the convex surface when the small mark 14 (or large mark 12) is irradiated at a position with a higher light intensity. If the light intensity distribution of the laser light 8 is a normal distribution, the height position of the concave surface will be output from the light receiver 224 as the lowest height position when the small mark 14 (or large mark 12) is irradiated at the peak position of the normal distribution. Therefore, as shown in FIG. 16 , the height position distribution on the surface of the sample 101 has a portion that continuously changes in the same direction over a range larger than the width of the small mark 14 (or large mark 12) (concave-convex mark), which is caused by the relative positional relationship between the light intensity distribution and the small mark 14 (or large mark 12) (concave-convex mark). To the left of the peak position of the height position distribution, the height position changes continuously in a direction lower from the convex height position toward the peak position. Conversely, to the right of the peak position of the height position distribution, the height position changes continuously in a direction higher from the peak position toward the convex height position.

[0063] In the first embodiment, the peak position refers not only to the upper maximum height position of a convex signal but also to the lower minimum height position of a concave signal. Here, the lower minimum height position is shown as the peak position.

[0064] The above-described height position distribution is calculated for each of the top, bottom, left and right positions of the small mark 14 (or large mark 12).

[0065] Next, the first mark position calculation unit 58 calculates the positions of the multiple marks using a change in a signal resulting from the state of the surface of the sample 101, which is obtained by the z sensor 220 by scanning the multiple marks with the laser light so that the multiple marks intersect with each other, while the height position of the sample is controlled to be a predetermined height position. In other words, the first mark position calculation unit 58 calculates the position of each mark using a height position distribution on the surface of the sample 101 for each mark, which is obtained by the z sensor 220 by scanning the multiple marks with the laser light so that the height position Z0 set for drawing is the reference height position. Specifically, it operates as follows.

[0066] The first mark position calculation unit 58 inputs the height position distribution at each of the top, bottom, left and right positions of the small mark 14 (or large mark 12) (concave and convex mark).

[0067] The first mark position calculation unit 58 calculates the peak position of a normal distribution obtained by approximating the height position distribution of the surface of the sample 101 using a density function of the normal distribution (hereinafter referred to as the normal distribution function) as the mark position.

[0068] 17 is a diagram showing an example of a height position distribution in embodiment 1. In FIG. 17, the vertical axis represents height position, and the horizontal axis represents position. In FIG. 17, measurement data from multiple measurement positions in the scanning direction is plotted. By approximating the measurement data from the multiple measurement positions in the scanning direction with a normal distribution function, the peak position of the approximation line is calculated as the mark position.

[0069] Alternatively, the first mark position calculation unit 58 may calculate the centroid position of the height position distribution on the surface of the sample 101, and calculate the centroid position as the mark position. The centroid position g can be calculated using the coordinate mi of the measurement data and the height position hi by the following equation (2), where i represents an index. (2) g = Σ(mi·hi) / Σhi

[0070] Alternatively, the first mark position calculation unit 58 may also suitably calculate, as the mark position, the position of the minimum height measurement value in the height position distribution on the surface of the sample 101. The minimum height measurement value among the measurement data at the multiple measurement positions shown in FIG.

[0071] When the mark portion is convex, the signal direction is convex, so it is also suitable to calculate the position of the maximum height measurement value as the position of the mark candidate signal.

[0072] The first mark position calculation unit 58 can then calculate the x position (x coordinate) of the center of the mark by calculating the average value of the x position measured at a position above the small mark 14 (or large mark 12) and the x position measured at a position below the small mark 14 (or large mark 12). Similarly, the y position (y coordinate) of the center of the mark can be calculated by calculating the average value of the y position measured at a position to the right of the small mark 14 (or large mark 12) and the y position measured at a position to the left of the small mark 14 (or large mark 12).

[0073] In addition, the change in signal due to the surface condition of the sample 101 of the mark obtained by the z sensor 220, which is used when calculating the positions of multiple marks, may be a change in the amount of light received by the photodetector 224 in addition to the change in height position indicated by the above-mentioned height position distribution.

[0074] As described above, if there is an error in the height position of the surface of the sample 101, the calculated mark position will have a positional deviation corresponding to the height error. Therefore, the following correction is made.

[0075] In the misalignment calculation step (S116), the misalignment calculation unit 60 calculates, for each mark, a misalignment amount Δr from the calculated position of the mark, using the incident angle θ of the laser light and the surface height positions of the sample 101 at multiple mark positions obtained from the acquired distribution of height positions for drawing on the surface of the sample 101. The distribution of height positions for drawing stored in the storage device 142 is obtained by a predetermined calculation formula, as described above. Therefore, by referring to the distribution of height positions for drawing, the misalignment calculation unit 60 calculates, for each mark, a misalignment amount using the height positions at the mark positions obtained by the predetermined calculation formula. For each mark, the height error Δh from the reference height position at the mark position and the incident angle θ can be substituted into formula (1) to determine the misalignment amount at the mark position.

[0076] In the correction step (S118), the correction unit 62 corrects the calculated position of each of the marks using a corresponding one of the calculated positional deviation amounts. In other words, the correction unit 62 corrects the calculated position of each of the marks using the calculated positional deviation amount Δr. Specifically, the actual mark position is the position obtained by adding the vector Δr to the coordinates (x0, y0) of the calculated position of the mark. For example, if the r direction coincides with the x direction, the actual mark position is the coordinates (x0 + Δr, y0).

[0077] This makes it possible to correct the positional deviation of the mark positions caused by an error in the height position of the sample 101. Information on the corrected position of each mark is output to the storage device 142 or the like and stored in the storage device 142 or the like.

[0078] Next, the center positions of the alignment marks are measured with high precision using an electron beam. Specifically, using information on the position of each mark after the positional deviation has been corrected, the stage 105 is moved to a position where the small marks 14 (concave and convex marks) can be irradiated with the electron beam, and the small marks 14 (concave and convex marks) are scanned with the electron beam to measure the positions of the small marks 14 (concave and convex marks).

[0079] In the mark scanning step (S126), first, using information on each mark position corrected for misalignment, the stage 105 is moved to a position where the small mark 14 (concave / convex mark) can be irradiated with the electron beam for each mark. Then, with the stage 105 moved to a position where the small mark 14 (concave / convex mark) can be irradiated with the electron beam, the deflector 209 deflects the electron beam to scan the small mark 14 (concave / convex mark). For example, as described in FIG. 11 , the small mark 14 is scanned at its top, bottom, left, and right positions. However, in this case, scanning within a range of, for example, 20 to 30 μm in the measurement direction is sufficient. In this way, the range scanned by the electron beam can be significantly reduced compared to conventional techniques. The electron beam used for such scanning is preferably one selected beam from the multi-beam 20, or several beams including beams adjacent to the selected beam. The beam selection is performed by turning on the selected beam or beams using the blanking aperture mechanism 204 and turning off the remaining beam array.

[0080] Secondary electrons emitted from the sample 101 when the small mark 14 (concave / convex mark) is scanned are detected by the detector 226. The detected data is converted from analog data to digital data and amplified by the detector 226, and is output from the detector 226 to the control computer 110.

[0081] In the mark position calculation (fine detection) step (S128), the second mark position calculation unit 68 calculates the center position of the small mark 14 (concave / convex mark) using secondary electron image data at the top, bottom, left, and right positions of the small mark 14 by the secondary electrons obtained in the mark scanning step (S126). For example, it is possible to measure the positions of both edges that make up the top, bottom, left, and right line widths of the small mark 14 in the secondary electron image, and determine the average values ​​of the center positions of the top and bottom line widths and the average values ​​of the center positions of the left and right line widths as the x and y coordinates of the small mark 14, respectively.

[0082] FIG. 18 is a conceptual diagram illustrating an example of the writing operation in the first embodiment. As shown in FIG. 18 , the position of the writing region 30 (thick line) on the sample 101 is defined based on the position of, for example, a small mark 14 that serves as the obtained alignment mark. The writing region 30 (thick line) is virtually divided, for example, in the y direction into a plurality of rectangular stripe regions 32 with a predetermined width. The example in FIG. 18 illustrates a case in which the writing region 30 on the sample 101 is divided, for example, in the y direction into a plurality of stripe regions 32 with widths substantially equal to the size of the designed irradiation region 34 (writing field) that can be irradiated with a single irradiation of the multibeam 20. The size in the x direction of the designed irradiation region 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 region 34 can be defined by the number of beams in the y direction × the beam pitch in the y direction.

[0083] First, the 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 stage 105 is moved, for example, in the −x direction, so that writing proceeds relatively in the x direction. The stage 105 is moved, for example, continuously 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.

[0084] Next, the irradiation area 34 of the multi-beam 20 is adjusted to be positioned at the left end of the second stripe area 32 or at a position further to the left, and the 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.

[0085] 18 shows the case where the writing of each stripe region 32 proceeds in the same direction, but this is not limiting. For example, the next stripe region 32 to be written after the stripe region 32 written in the x direction may be written in the -x direction by moving the stage 105, for example, in the x direction. 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-beams 20 formed by passing through each hole 22 in the shaping aperture array substrate 203 simultaneously form multiple shot patterns, up to the same number as each hole 22.

[0086] 18 shows the case where the stage is moved once for the writing process of each stripe region, but this is not limiting. Multiple writing may also be performed by moving the stage multiple times over the same position. In this case, it is preferable to perform multiple writing while shifting the stage in the y direction by an amount equal to 1 / n of the width of the stripe region, for example.

[0087] FIG. 19 shows an example of a multibeam irradiation area and a target pixel for drawing in the first embodiment. In FIG. 19 , 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 size may be 1 / n (n is an integer greater than or equal to 1) of the beam size. The example in FIG. 19 shows a case where the target region for drawing on the sample 101 is divided, for example, in the y direction, into a plurality of stripe areas 32, each having a width substantially equal to the size of the irradiation region 34 (drawing field) that can be irradiated with one irradiation of the multibeam 20. The size of the rectangular irradiation region 34 in the x direction can be defined by the number of beams in the x direction multiplied by the beam pitch in the x direction. The size of the rectangular irradiation region 34 in the y direction can be defined by the number of beams in the y direction multiplied by the beam pitch in the y direction. In the example of Figure 19, for example, a 512 x 512 array of multi-beams is shown as an 8 x 8 array of multi-beams. A plurality of pixels 28 (beam drawing positions) that can be irradiated with a single 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 Figure 19, each sub-irradiation area 29 is shown as being composed of, for example, 4 x 4 pixels.

[0088] In the shot data generation step (S130), first, the shot data generation unit 70 generates shot data for each pixel 36. Specifically, the operation is as follows. First, the shot data generation unit 70 reads out drawing data from the storage device 140, and calculates, for each pixel 36, the pattern area density ρ′ within that pixel 36. This process is executed, for example, for each stripe region 32.

[0089] Next, the shot data generation unit 70 first virtually divides the writing region (here, for example, the stripe region 32) into a plurality of proximity mesh regions (mesh regions for calculating proximity effect correction) in a mesh shape of a predetermined size. The size of the proximity mesh region is preferably set to about 1 / 10 of the range of influence of the proximity effect, for example, about 1 μm. The shot data generation unit 70 reads the writing data from the storage device 140, and calculates, for each proximity mesh region, the pattern area density ρ" of the pattern to be placed in that proximity mesh region.

[0090] Next, the shot data generation unit 70 calculates a proximity effect correction exposure coefficient Dp(x) (corrected exposure dose) for correcting the proximity effect for each proximity mesh region. The unknown proximity effect correction exposure coefficient Dp(x) can be defined by a threshold model for proximity effect correction similar to the conventional method, using the backscattering coefficient η, the exposure dose threshold Dth of the threshold model, the pattern area density ρ", and the distribution function g(x).

[0091] Next, the shot data generation unit 70 calculates, for each pixel 36, an incident irradiation amount D(x) (dose amount) for irradiating the pixel 36. The incident irradiation amount D(x) may be calculated, for example, as a value obtained by multiplying the base irradiation amount Dbase by the proximity effect correction irradiation coefficient Dp and the pattern area density ρ'. The base irradiation amount Dbase can be defined, for example, as Dth / (1 / 2 + η). As a result, the proximity effect-corrected incident irradiation amount D(x) for each pixel 36 can be obtained based on the layout of the multiple figure patterns defined in the drawing data.

[0092] Next, the shot data generating unit 70 calculates the irradiation time for each pixel 36. The irradiation time for each pixel 36 can be calculated by dividing the incident irradiation amount D(x) of the pixel by the current density J.

[0093] In the data processing step (S132), the data processing unit 72 rearranges the obtained irradiation time data for each pixel 36 in shot order and stores the data in the storage device 142. The transfer processing unit 74 transfers the irradiation time data to the deflection control circuit 130 in shot order.

[0094] In the writing step (S140), under the control of the control unit 76, the writing mechanism 150 writes a pattern on the sample 101 using the multibeams 20 (electron beams) based on information about the corrected positions of each mark, while controlling the height position of the sample 101 so that the height position Z0 set for writing becomes the reference height position. As described above, the writing mechanism 150 writes a pattern on the sample 101 on the stage 105 using the multibeams 20 while moving the stage 105. At this time, if there are irregularities in the height distribution on the sample surface, the focal position adjusted by the objective lens 207 will be shifted. Therefore, for example, the electrostatic lens 212 dynamically corrects the shift in the focal position of the multibeams 20 according to each height position by referring to the height position distribution on the sample surface for writing stored in the storage device 142 (performing dynamic focusing). Alternatively, if the response performance is satisfactory (no delay occurs), the objective lens 207 may be controlled to adjust the focal position of the multibeams 20 according to each height position by referring to the height position distribution on the sample surface.

[0095] In multi-beam lithography, while lithography is being performed, shot data for the region to be lithographed later is generated in parallel. For example, while lithography is being performed on the kth stripe region 32, shot data for the k+2th stripe region 32 is generated in parallel. By repeating this operation, lithography is performed on all stripe regions 32.

[0096] Fig. 20 is a diagram for explaining an example of a multi-beam writing operation in embodiment 1. The example of Fig. 20 shows a case where writing is performed with four different beams within each sub-irradiation area 29, each of which includes one beam irradiation position of the multi-beams 20 and is surrounded by the inter-beam pitch. The example of Fig. 20 also shows a writing operation in which the stage 105 continuously moves at a speed equivalent to a distance of two beam pitches while writing ¼ of the area within each sub-irradiation area 29 (one times the number of beams used for irradiation). The example of Fig. 20 shows a case where each sub-irradiation area 29 is composed of, for example, 4 × 4 pixels.

[0097] In the drawing operation shown in the example of Figure 20, for example, while the stage 105 moves a distance equivalent to 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 these four pixels 36 are being drawn (exposed), the deflector 208 deflects the entire multibeam 20 collectively so that the relative position of the irradiation region 34 with respect to the sample 101 does not shift due to the movement of the stage 105, thereby causing the irradiation region 34 to follow the movement of the stage 105. In other words, tracking control is performed. When one tracking cycle is completed, tracking is reset and the system returns to the previous tracking start position. Note that, since the drawing of the first pixel row from the left in each sub-irradiation region 29 has been completed, after a tracking reset, the deflector 209 first deflects the beam different from the first pixel row in the next tracking cycle to align (shift) the drawing position of the beam different from that of the first pixel row so as to draw an undrawn pixel row, for example, the second pixel row from the left, in each sub-irradiation region 29. By repeating this operation during drawing of the stripe region 32, the positions of the irradiation regions 34 (34a to 34o) of the multi-beam 20 are sequentially moved, and drawing is performed, as shown in the lower diagram of FIG.

[0098] As described above, according to the first embodiment, it is possible to measure with high accuracy the positions of a plurality of marks formed on the sample 101, whose concave and convex surfaces are made of the same material. Furthermore, when correcting the mark positions, the correction can be made using information obtained in the drawing operation (acquisition of the height position distribution for drawing) without having to take the trouble of measuring the height position of each mark. As a result, it is possible to suppress an increase in the drawing time.

[0099] [Embodiment 2] In the first embodiment, the height of the mark position obtained from the height position distribution for drawing is used for correction, but this is not limited to this. In the second embodiment, a configuration will be described in which the height of the mark position obtained from the height position distribution around the mark position measured in the mark rough search step (S112) is used for correction.

[0100] The configuration of the writing apparatus 100 in the second embodiment may be the same as that shown in FIG. 1. Also, a flowchart showing an example of the main steps of the writing method in the second embodiment may be the same as that shown in FIG. 8. Note that in the second embodiment, similarly to the first embodiment, the mark scanning step (S126) and the mark position calculation (fine detection) step (S128) may be omitted depending on the required measurement accuracy of the mark position. In such a case, the correction step (S118) is followed by the shot data generation step (S130).

[0101] The contents other than those specifically explained below are the same as those of the first embodiment.

[0102] The contents of the drawing height position measurement / calculation process (S102), drawing height position setting process (S104), drawing height position distribution acquisition process (S106), mark search process (S110), mark rough search process (S112), and mark position calculation process (S114) are the same as those in embodiment 1.

[0103] In the positional deviation calculation step (S116), the positional deviation calculation unit 60 calculates, for each mark, the positional deviation Δr from the calculated position of the mark, using the incident angle θ of the laser light and the surface height positions of the sample 101 in the vicinity of at least multiple mark positions obtained when scanning the multiple marks in the mark rough search step (S112).

[0104] FIG. 21 is a diagram showing an example of the surface height position of the sample near the mark position, including the mark position, in the second embodiment. In the example of FIG. 21 , the position of the bottom peak indicates the mark position. In this case, the misalignment calculation unit 60 calculates the misalignment amount for each mark using multiple height position information at multiple positions, including the mark position, obtained within the range scanned for the mark. In the example of FIG. 21 , the height position Zk is, for example, the average value of the height at the bottom peak position, which is the mark position, and the heights at multiple positions (e.g., two positions) near the outside of the recess. Alternatively, the height position Zk is, for example, the average value of the heights at multiple positions, including the height at the bottom peak position, which is the mark position, the height at a position near the outside of the recess, and the heights at positions other than the peak of the recess. Then, the misalignment amount Δr is calculated using the difference Δh from the writing height position Z0.

[0105] Alternatively, the misalignment amount calculation unit 60 may calculate the misalignment amount for each mark using multiple height position information at multiple positions excluding the mark position, which is obtained within the range where the mark is scanned. In the example of Fig. 21, the height position Zk is set to, for example, the average value of heights at multiple positions (e.g., two positions) near the outside of the recess, excluding the height of the peak position below the mark position. Then, the misalignment amount Δr is calculated using the difference Δh from the drawing height position Z0.

[0106] The contents of each step after the correction step (S118) are the same as those in the first embodiment.

[0107] As described above, according to the second embodiment, the sample surface height Zk at the mark position is calculated using the height position distribution obtained when performing a rough search for the mark position, which eliminates the need to measure the sample surface height Zk at the mark position for correction. In this way, when correcting the mark position, the correction can be performed using information obtained in the drawing operation (mark rough search). Consequently, an increase in the drawing time can be suppressed.

[0108] [Embodiment 3] In the above-described embodiments, the configuration for calculating the positional deviation Δr using the height of the mark position measured or calculated while controlled to the height position Z0 for drawing has been described, but the method for obtaining a highly accurate mark position is not limited to this. In embodiment 3, a configuration for measuring the mark position will be described in a state where the positional deviation is within an allowable range without correction, or where the positional deviation is small even when correction is performed.

[0109] The configuration of the drawing device 100 in the third embodiment may be the same as that shown in Fig. 1. In addition, the contents other than those specifically described below may be the same as those in the first or second embodiment.

[0110] Fig. 22 is a flowchart showing an example of main steps of the writing method according to the third embodiment. In Fig. 22, the writing method according to the third embodiment carries out a series of steps including a mark search step (S101), a height position calculation step for mark search (S103), a height position setting step for mark search (S105), a rough mark search step (S112), a mark position calculation step (S114), a position deviation calculation step (S115), a correction step (S117), a height position measurement / calculation step for writing (S120), a height position setting step for writing (S122), a height position distribution acquisition step for writing (S124), a mark scan step (S126), a mark position calculation (fine detection) step (S128), a shot data generation step (S130), a data processing step (S132), and a writing step (S140).

[0111] Also, similarly to the first and second embodiments, the mark scanning step (S126) and the mark position calculation (fine detection) step (S128) may be omitted depending on the required measurement accuracy of the mark position.

[0112] Furthermore, in the third embodiment, the positional deviation amount calculation step (S115) and the correction step (S117) may be omitted depending on the positional deviation accuracy of the mark positions.

[0113] In the mark search step (S101), the sample 101 is transported onto the stage 105, and the large mark 12 is searched for in a wide area on the sample 101 using the z sensor 220.

[0114] FIG. 23 is a diagram illustrating a stage mechanism and a height position for mark search in the third embodiment. In FIG. 23, the stage 105 has an XY stage 107 and a Z stage 108. In the example of FIG. 23, the Z stage 108 is arranged on the XY stage 107. The mark stage 106 is arranged on the XY stage 107 in parallel with the Z stage 108. The sample 101 is supported by a plurality of pins 211 on the Z stage 108. For example, it is supported at three points. The outer periphery of the sample 101 is supported by the plurality of pins 211. Therefore, as shown in FIG. 23, deflection occurs due to its own weight. Here, the actual large mark 12 is searched for using the z sensor 220 based on the position of the designed large mark 12. The heights of the outer periphery and center of the sample 101 are measured. Specifically, with the sample 101 transported onto the stage 105, the XY stage 107 is driven to align the laser beam irradiation position of the z sensor 220 with the outer periphery of the sample 101. Then, in this state, the height of the outer periphery of the sample 101 is measured. As the outer periphery of the sample 101, for example, measurements are made at one location on each of the four outer peripheries of the sample 101. Then, in a similar manner, the XY stage 107 is driven to align the laser beam irradiation position of the z sensor 220 with the center position of the sample 101. Then, in this state, the height of the center position of the sample 101 is measured. The search method is the same as the mark search step (S110) in the first and second embodiments. The measured height position information is output to the control computer 110.

[0115] The first height position distribution calculation unit 53 inputs the measured height position information and calculates the height position distribution. The mark area identification unit 54 then searches for a position where the height position is lower than the surrounding area, and identifies such a position as the alignment mark area 10.

[0116] In the mark search height position calculation step (S103), the height position calculation unit 50 calculates a mark search height position (first height position) using height position information obtained by the z sensor 220 at each position where multiple marks are assumed to exist. When alignment marks (large marks 12 or small marks 14) are arranged at the four corners of the surface of the sample 101, the average value of multiple height positions measured by the z sensor 220 at or near the four corner mark positions (positions of the large marks 12 or small marks 14) is calculated as the mark search height position Z0'.

[0117] In the mark search height position setting step (S105), the Z stage 108 is driven to control the height position of the sample 101 so that the calculated height position Z0' becomes the reference height position. As shown in Fig. 23, for example, the surface height position of the mark stage 106 is set as the reference position, and the Z stage 108 moves the sample 101 in the z direction so that the calculated height position Z0' coincides with this reference height position.

[0118] In the mark rough search step (S112), the height position of the sample 101 is controlled so that the mark search height position Z0' becomes the reference height position, and then the laser light is used to scan the multiple marks so as to intersect with the multiple marks using the z sensor 220. The details are the same as those in the first and second embodiments except that the height position of the sample 101 is controlled so that the mark search height position Z0' becomes the reference height position.

[0119] In the mark position calculation step (S114), the first mark position calculation unit 58 calculates the positions of the multiple marks using a change in a signal resulting from the state of the surface of the sample 101, which is obtained by the z sensor 220 by scanning the multiple marks with a laser beam so as to intersect with the multiple marks, while the height position of the sample 101 is controlled so that the mark search height position Z0' is the reference height position. In other words, the first mark position calculation unit 58 calculates the position of each mark using a height position distribution on the surface of the sample 101 for each mark, which is obtained by the z sensor 220 by scanning the multiple marks with a laser beam so as to intersect with the multiple marks, while the height position of the sample 101 is controlled so that the mark search height position Z0' is the reference height position. The details are the same as those in the first and second embodiments, except that the height position of the sample 101 is controlled so that the mark search height position Z0' is the reference height position.

[0120] In the third embodiment, for example, the average value of the height positions of a plurality of marks is the mark search height position Z0', and the mark search height position Z0' is adjusted to the reference height position. Therefore, the difference Δh, which is the amount by which the height at each mark position deviates from the reference height position, can be made smaller than when the writing height position Z0 is adjusted to the reference height position. Therefore, the positional deviation amount Δr caused by the deviation of the height position of the sample 101 can be made small enough to be negligible (within an acceptable range). Therefore, sufficient positional accuracy can be obtained without correcting the positional deviation amount Δr.

[0121] However, if the accuracy of the mark position is to be further increased, the positional deviation calculation step (S115) and the correction step (S117) may be carried out.

[0122] In the positional deviation calculation step (S115), the positional deviation calculation unit 60 calculates, for each mark, the positional deviation from the calculated mark position using the incident angle θ of the laser light and the surface height positions of the sample 101 near at least multiple mark positions obtained when scanning the multiple marks. Specifically, the positional deviation calculation unit 60 uses the height positions of the four corner mark positions (the positions of the large mark 12 or the small mark 14) or their vicinity measured by the z sensor 220 in the mark search step (S101). In other words, the positional deviation Δr is calculated using the difference Δh between the height of each mark position used in calculating the mark search height position Z0′ in the mark search height position calculation step (S103) and the reference height position. The positional deviation Δr can be calculated using equation (1).

[0123] In the correction step (S117), the correction unit 62 corrects the calculated position of each mark using the calculated positional deviation Δr. The correction method is the same as the correction step (S118) in the first and second embodiments.

[0124] As a result, the mark position can be obtained with even higher accuracy.

[0125] Here, since the mark search height position Z0' of the sample 101 has been adjusted to the reference height position, the writing step (S140) cannot be performed in this state. Therefore, the writing height position Z0 is readjusted to the reference height position. For this purpose, the writing height position measuring / calculating step (S120), the writing height position setting step (S122), and the writing height position distribution acquiring step (S124) are performed. The contents of each of the writing height position measuring / calculating step (S120), the writing height position setting step (S122), and the writing height position distribution acquiring step (S124) are the same as the contents of each of the writing height position measuring / calculating step (S102), the writing height position setting step (S104), and the writing height position distribution acquiring step (S106) in the first and second embodiments. This allows the sample surface height to be adjusted in the writing step (S140).

[0126] The contents of each of the mark scanning process (S126), mark position calculation (fine detection) process (S128), shot data generation process (S130), data processing process (S132), and drawing process (S140) are the same as those in the first and second embodiments.

[0127] Specifically, in the drawing process (S140), the drawing mechanism 150 draws a pattern on the sample 101 using the multi-beam 20 based on information on the position of each mark, while controlling the height position of the sample 101 so that the drawing height position Z0 (second height position) set for drawing becomes the reference height position.

[0128] As described above, according to the third embodiment, the mark position is measured with the mark position obtained at the height position for mark search or a height position in the vicinity thereof set as the reference height, so that the positional deviation of the mark position can be reduced. Furthermore, when correction is performed, the accuracy can be further improved.

[0129] The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. For example, a mark may be used in which the concave and convex surfaces are made of different materials.

[0130] 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.

[0131] In addition, all mark position measurement devices and mark position measurement methods, charged particle beam writing devices, and charged particle beam writing methods that include the elements of the present invention and that can be appropriately modified by a person skilled in the art are included in the scope of the present invention.

[0132] One aspect of the present invention relates to a mark position measurement device and a mark position measurement method, which can be used, for example, in a technique for measuring the position of an alignment mark on a sample to be written.

[0133] DESCRIPTION OF SYMBOLS 8 Laser light 9 Reflected light 10 Alignment mark area 12 Large mark 14 Small mark 20 Multi-beam 22 Hole 24 Control electrode 25 Passage hole 26 Counter electrode 29 Sub-irradiation area 30 Drawing area 31 Blanking aperture array substrate 32 Stripe area 34 Irradiation area 36 Pixel 41 Control circuit 50 Height position calculation unit 52 Height position distribution acquisition unit 53 First height position distribution calculation unit 54 Mark area identification unit 56 Second height position distribution calculation unit 58 First mark position calculation unit 60 Position deviation amount calculation unit 62 Correction unit 68 Second mark position calculation unit 70 Shot data generation unit 72 Data processing unit 74 Transfer processing unit 76 Control unit 80 Glass substrate 82 Light-shielding film 84 Low thermal expansion glass substrate 86 Multilayer film 88 Absorber film 100 lithography device 101 Sample 102 Electron microscope column 103 lithography chamber 105 Stage 106 Marking table 107 XY stage 108 Z stage 110 Control computer 112 Memory 130 Deflection control circuit 132, 134 DAC amplifier unit 135 Detection circuit 136 Lens control circuit 138 Stage control mechanism 139 Stage position measuring device 140, 142 Storage device 150 lithography mechanism 160 Control system circuit 200 Electron beam 201 Electron gun 202 Illumination lens 203 Shaping aperture array substrate 204 Blanking aperture array mechanism 205 Reduction lens 206 Limiting aperture substrate 207 Objective lens 208 Deflector 209 Deflector 210 Mirror 211 Pin 212 electrostatic lens 220 z sensor 222 light projector 224 light receiver 226 detector 330 membrane region

Claims

a sensor having an illuminator for irradiating the sample with a laser beam and a light receiver for receiving light reflected from the sample in association with the irradiation of the laser beam and outputting a signal of a height position at the irradiated position on the sample surface; a height position distribution acquisition circuit for acquiring a height position distribution of the sample surface based on a result acquired by the sensor while the height position of the sample is controlled to a predetermined height position; a mark position calculation circuit for calculating positions of the multiple marks using a change in a signal caused by a state of the sample surface of the marks acquired by the sensor by scanning the multiple marks with the laser beam so as to intersect with the multiple marks while the height position of the sample is controlled to the predetermined height position; a position deviation calculation circuit for calculating a position deviation amount from the calculated position of the mark using the incident angle of the laser beam and the surface height positions of the sample at the multiple mark positions acquired from the acquired height position distribution of the sample surface; and a correction circuit for correcting the calculated position of the mark by using a corresponding position deviation amount among the multiple calculated position deviation amounts for the multiple marks.

2. The mark position measurement device described in claim 1, characterized in that the height position distribution acquisition circuit acquires the height position distribution of the surface of the sample based on the results obtained by the sensor, while the height position of the sample is controlled so that the height position set for drawing becomes the reference height position, and the mark position calculation circuit calculates the positions of the multiple marks using the height position distribution of the surface of the sample of the marks obtained by the sensor by scanning the multiple marks with the laser light so that it intersects with the multiple marks, while the height position of the sample is controlled so that the height position set for drawing becomes the reference height position.

3. The mark position measuring device described in claim 1, characterized in that the sensor outputs height position information measured at multiple positions on the surface of the sample, the height position distribution acquisition circuit calculates the height position distribution of the surface of the sample using a predetermined formula using the height position information of the multiple positions on the surface of the sample, and the position deviation calculation circuit calculates the position deviation amount for each mark using the height position at that mark position obtained by the predetermined formula.

4. The mark position measurement device described in claim 1, characterized in that the position deviation calculation circuit calculates the position deviation from the calculated mark position using the incident angle of the laser light and the surface height positions of the sample at least in the vicinity of the multiple mark positions obtained when scanning the multiple marks.

5. The mark position measurement device described in claim 4, characterized in that the position deviation calculation circuit calculates the position deviation for each mark using either multiple pieces of height position information at multiple positions including the mark position obtained within the range in which the mark is scanned, or multiple pieces of height position information at multiple positions excluding the mark position obtained within the range in which the mark is scanned.

6. A mark position measurement device comprising: a movable stage for placing a sample on which a plurality of marks are formed; a sensor having an illuminator for irradiating the sample with laser light and a light receiver for receiving light reflected from the sample due to the irradiation of the laser light and outputting a signal of a height position at the irradiated position on the surface of the sample; a height position calculation circuit for calculating a first height position using height position information obtained by the sensor at each position where the plurality of marks are assumed to be present; a mark position calculation circuit for calculating positions of the plurality of marks using a change in a signal caused by the state of the surface of the sample of the marks obtained by the sensor by scanning the plurality of marks with the laser light so as to intersect with the plurality of marks, while controlling the height position of the sample so that the first height position becomes a reference height position; and a control circuit for controlling the height position of the sample so that a second height position set for drawing becomes the reference height position, in order to draw a pattern on the sample using a charged particle beam.

7. The mark position measuring device according to claim 6, further comprising: a position deviation calculation circuit that calculates, for each of the marks, a position deviation amount from the calculated position of the mark using the incident angle of the laser light and the surface height positions of the sample at least in the vicinity of the positions of the multiple marks obtained when scanning the multiple marks; and a correction circuit that corrects the calculated position of the mark using the calculated position deviation amount for each of the marks.

8. A mark position measurement method comprising the steps of: measuring a height position of a surface of the sample with a sensor having an irradiator that irradiates the sample with laser light and a light receiver that receives reflected light from the sample due to the irradiation of the laser light and outputs a signal of a height position at the irradiated position on the surface of the sample, while controlling the height position of the sample to a predetermined height position; obtaining a height position distribution of the surface of the sample based on the results measured by the sensor; calculating positions of the multiple marks using a change in a signal caused by a state of the surface of the sample of the marks obtained by scanning the multiple marks with the laser light so as to intersect with the multiple marks, while controlling the height position of the sample to the predetermined height position; calculating a positional deviation from the calculated position of the mark using the incident angle of the laser light and the surface height positions of the sample at the multiple mark positions obtained from the obtained distribution of height positions of the surface of the sample; and correcting the calculated position of the mark using a corresponding one of the calculated positional deviations for the multiple marks and outputting the corrected position.

9. A mark position measurement method comprising: measuring height information at each position where a plurality of marks are assumed to be present on a sample placed on a stage and having a plurality of marks formed thereon, using a sensor having an illuminator that irradiates the sample with a laser light and a light receiver that receives reflected light from the sample due to the irradiation of the laser light and outputs a signal of the height position at the irradiation position on the surface of the sample; calculating a first height position using the height position information obtained by the sensor at each position where the plurality of marks are assumed to be present; calculating and outputting positions of the plurality of marks using a change in a signal due to the state of the surface of the sample of the marks obtained by the sensor by scanning the plurality of marks with the laser light so as to intersect with the plurality of marks, while controlling the height position of the sample so that the first height position becomes a reference height position; and controlling the height position of the sample so that a second height position set for drawing becomes the reference height position in order to draw a pattern on the sample using a charged particle beam.

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