Inspection device and inspection method

Abstract

To provide an inspection device and inspection method which can easily improve inspection accuracy.SOLUTION: According to one embodiment, there is provided an inspection device including a control unit, an irradiation unit and a generation unit. The control unit obtains the irradiation amount of each of a plurality of first beams on the basis of pattern information of a plurality of inspection regions in an inspection object. The inspection object includes the plurality of inspection regions. The plurality of first beams correspond to the plurality of inspection regions. The irradiation unit preliminarily irradiates the plurality of inspection regions with the plurality of first beams in the respectively obtained irradiation amounts. The irradiation unit irradiates the plurality of inspection regions with the plurality of second beams in the state where the preliminary irradiation is performed. The generation unit generates images of the plurality of inspection regions irradiated with the plurality of second beams.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present embodiment relates to an inspection apparatus and an inspection method. [Background technology]

[0002] In an inspection device such as an electron microscope, a predetermined inspection is performed by irradiating an inspection object with a charged particle beam and generating an image of the inspection object. It is desirable to improve the accuracy of the inspection. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-119423 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of one embodiment is to provide an inspection device and an inspection method that can easily improve the accuracy of inspection. [Means for solving the problem]

[0005] According to one embodiment, an inspection device is provided that has a control unit, an irradiation unit, and a generation unit. The control unit calculates the irradiation doses of the multiple first beams based on pattern information of multiple inspection areas in the inspection object. The multiple inspection areas are obtained by dividing the irradiation area into multiple areas. The multiple inspection areas are arranged in a first direction and a second direction. The inspection object includes multiple inspection areas. The multiple first beams correspond to the multiple inspection areas. The irradiation unit preliminarily irradiates the multiple inspection areas with the multiple first beams at the calculated irradiation doses, respectively. The irradiation unit irradiates the multiple inspection areas with the multiple second beams in a state in which the preliminary irradiation has been performed. The generation unit generates images of the multiple inspection areas irradiated with the multiple second beams. The control unit determines, for each of the multiple inspection regions, the irradiation amount of the first beam corresponding to the inspection region to be greater as the pattern size or the inter-pattern distance is smaller. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram showing a configuration of an inspection device according to an embodiment. [Diagram 2] FIG. 1 illustrates multiple beams and multiple inspection regions in an embodiment. [Diagram 3] 5A and 5B are diagrams showing pattern information and irradiation amounts of a plurality of inspection regions in the embodiment. [Figure 4] 6A to 6C are diagrams showing an adjustment operation of the irradiation amount in the embodiment. [Diagram 5] 5A to 5C are diagrams showing the operation of the inspection device according to the embodiment. [Figure 6] 5A to 5C are diagrams showing the operation of the inspection device according to the embodiment. [Figure 7] 4 is a flowchart showing the operation of the inspection apparatus according to the embodiment. [Figure 8] FIG. 13 is a diagram showing the configuration of an inspection device according to a modified example of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] An inspection device according to an embodiment will be described in detail below with reference to the accompanying drawings. Note that the present invention is not limited to the embodiment.

[0008] (Embodiment) The inspection device according to the embodiment is a multi-beam type inspection device, and can be configured as shown in Fig. 1. Fig. 1 is a diagram showing the configuration of the inspection device 1. In the following, the vertical direction is defined as the x direction, and two directions perpendicular to each other in a plane perpendicular to the z direction are defined as the x direction and the y direction.

[0009] The inspection apparatus 1 splits a charged particle beam EB and irradiates a plurality of inspection regions of the inspection object OB with the split beams (multi-beams) MB-1 to MB-n. n is any integer equal to or greater than 2. The inspection apparatus acquires images of the plurality of inspection regions and performs a predetermined inspection on the inspection object OB. The inspection object OB may be an original plate for nanoimprinting or a device substrate on which a device is formed. The original plate for nanoimprinting is also called a template. The predetermined inspection may be an inspection of the presence or absence of defects in the inspection object OB or an inspection of whether the dimensions of a pattern formed on the inspection object OB are within an appropriate range.

[0010] The inspection apparatus 1 performs a preliminary irradiation of the inspection object OB prior to irradiation with a plurality of beams MB-1 to MB-n for inspection.

[0011] For example, the inspection apparatus 1 acquires pattern information of a plurality of inspection areas. The inspection apparatus 1 determines the dose of preliminary irradiation corresponding to each of the plurality of inspection areas based on the pattern information of the plurality of inspection areas. The inspection apparatus 1 may determine the dose of preliminary irradiation so that the charge amounts are uniform among the plurality of inspection areas. The inspection apparatus 1 preliminarily irradiates each of the plurality of inspection areas in the inspection object OB with the beam MB at the determined dose. After that, the inspection apparatus 1 irradiates the plurality of inspection areas with the plurality of inspection beams MB-1 to MB-n in a state in which the preliminary irradiation has been performed. The plurality of inspection beams MB-1 to MB-n may have equal doses.

[0012] This allows the primary electrons to be irradiated by the inspection beam irradiation in a state where the emission rate of secondary electrons relative to primary electrons in multiple inspection regions has been equalized by the preliminary beam irradiation. As a result, the emission rate of secondary electrons for inspection can be made to more appropriately reflect the surface state of the inspection target, so that the variation in brightness or contrast for each inspection image can be suppressed, and the inspection accuracy by the inspection device 1 can be improved.

[0013] Specifically, the inspection apparatus 1 has an inspection mechanism 2, a control computer 3, a pattern information storage device 4, a material information storage device 5, a pre-irradiation map storage device 6, a storage device 7, a display device 8, and an input device 9. The control computer 3 is connected to the inspection mechanism 2, the pattern information storage device 4, the inspection object OB material information storage device 5, the pre-irradiation map storage device 6, the storage device 7, the display device 8, and the input device 9.

[0014] The inspection mechanism 2 includes an electron column 10, a sample chamber 20, an electron gun control unit 31, an illumination lens control unit 32, a shaping aperture control unit 33, a blanking aperture control unit 34, a reduction lens control unit 35, a limiting aperture control unit 36, an objective lens control unit 37, a deflector control unit 38, a signal processing unit 39, an image generating unit 41, and a stage control unit 42. A space between the electron column 10 and the sample chamber 20 is configured to allow multi-beams (plurality of beams MB-1 to MB-n) to pass through, and a space is configured to allow multiple secondary beams SE-1 to SE-n to pass through.

[0015] The electron column 10 has an electron gun 11, an illumination lens 12, a shaping aperture 13, a blanking aperture 14, a reduction lens 15, a limiting aperture 16, an objective lens 17, a deflector 18, and a detector 19. The electron gun 11, the illumination lens 12, the shaping aperture 13, the blanking aperture 14, the reduction lens 15, the limiting aperture 16, the objective lens 17, the deflector 18, and the detector 19 are each contained within a column wall 10a. The inside of the column wall 10a is configured so that it can be reduced in pressure by a vacuum device (not shown).

[0016] The sample chamber 20 has a stage 21 and a driving mechanism 22. The stage 21 is a plate-like member extending in the X and Y directions, and an object to be inspected OB is placed on the +z surface. The driving mechanism 22 can move the stage 21 in the X direction, the Y direction, the Z direction, a rotational direction around the X axis, a rotational direction around the Y axis, and a rotational direction around the Z axis. The X, Y, and Z directions related to driving the stage 21 correspond to the x, y, and z directions defined above.

[0017] The control computer 3 is connected to the electron gun control unit 31, the illumination lens control unit 32, the shaping aperture control unit 33, the blanking aperture control unit 34, the reduction lens control unit 35, the limiting aperture control unit 36, the objective lens control unit 37, the deflector control unit 38, the signal processing unit 39, the image generation unit 41, and the stage control unit 42. The control computer 3 generates various control signals and sends them to the electron gun control unit 31, the illumination lens control unit 32, the shaping aperture control unit 33, the blanking aperture control unit 34, the reduction lens control unit 35, the limiting aperture control unit 36, the objective lens control unit 37, the deflector control unit 38, the signal processing unit 39, the image generation unit 41, and the stage control unit 42, respectively.

[0018] The stage control unit 42 is connected to the driving mechanism 22 in the sample chamber 20. The inspection object OB is placed on the +z side surface of the stage 21. The stage control unit 42 controls the driving mechanism 22 to move the stage 21 so that multiple inspection regions on the inspection object OB correspond to the irradiation positions of multiple beams MB-1 to MB-n.

[0019] The electron gun control unit 31 controls the operation of the electron gun 11, and causes the electron gun 11 to emit a charged particle beam EB or to stop the emission of the charged particle beam EB. A high-voltage power supply circuit (not shown) is connected to the electron gun 11. The electron gun control unit 31 is connected to the high-voltage power supply circuit. The high-voltage power supply circuit applies an acceleration voltage and a predetermined bias voltage between a cathode and an anode (not shown) in the electron gun 11 under the control of the electron gun control unit 31. The electron gun 11 generates and emits a charged particle beam EB by accelerating a group of electrons emitted from the cathode by applying a predetermined bias voltage from the high-voltage power supply circuit and heating the cathode to a predetermined temperature. The charged particle beam EB is, for example, an electron beam.

[0020] An illumination lens 12, a shaping aperture 13, a blanking aperture 14, a reduction lens 15, a limiting aperture 16, an objective lens 17, a deflector 18, and an (inspection object OB) stage 21 are arranged in this order along the optical axis of the chief ray of the charged particle beam EB. In addition, a detector 19 is arranged near the deflector 18 at a position shifted from the optical axis of the chief ray.

[0021] The illumination lens control unit 32 is connected to the illumination lens 12 in the lens barrel wall 10a. The illumination lens control unit 32 controls the illumination lens 12 and adjusts the z position of the illumination lens 12, so that the charged particle beam EB received by the illumination lens 12 from the electron gun 11 is guided, for example, in a collimated state to the shaping aperture 13. The illumination lens 12 changes the direction of the charged particle beam EB to be approximately perpendicular to the shaping aperture 13, and illuminates the entire shaping aperture 13 with the charged particle beam EB.

[0022] The shaping aperture control unit 33 is connected to the shaping aperture 13. The shaping aperture 13 has a structure in which a plurality of rectangular holes are formed. The shaping aperture control unit 33 controls the shaping aperture 13 so that the charged particle beam EB is shaped into multiple beams by the shaping aperture 13. That is, the charged particle beam EB passes through the plurality of rectangular holes in the shaping aperture 13, and is thereby split into a plurality of beams MB-1 to MB-n. Each beam MB is, for example, an electron beam. A collection of the plurality of beams MB-1 to MB-n is also called a multibeam.

[0023] The blanking aperture control unit 34 is connected to the blanking aperture 14. The blanking aperture 14 individually deflects each of the multi-beams formed by the shaping aperture. The blanking aperture control unit 34 controls the blanking aperture 14 to tilt the optical axis of each beam from the z direction, for example, so that the multiple beams MB-1 to MB-n are scanned in multiple inspection regions.

[0024] The reduction lens control unit 35 is connected to the reduction lens 15. The reduction lens 15 reduces the beams MB-1 to MB-n that have passed through the blanking aperture 14, and changes the direction of each of the beams MB-1 to MB-n so that they are directed toward the center of the limiting aperture 16. The reduction lens control unit 35 controls the reduction lens 15, and adjusts the z position of the reduction lens 15, etc., to refract the multiple beams MB-1 to MB-n through the reduction lens 15 and collect them in the vicinity of the opening of the limiting aperture 16.

[0025] The limiting aperture control unit 36 ​​is connected to the limiting aperture 16. The limiting aperture control unit 36 ​​controls the limiting aperture 16, and adjusts the xy position of the limiting aperture 16, so that the hole 16a of the limiting aperture 16 is located near the focusing point of the multiple beams MB-1 to MB-n. The limiting aperture 16 blocks the beam MB deflected by the blanking aperture 14. On the other hand, the beam MB not deflected by the blanking aperture 14 passes through the hole 16a at the center of the limiting aperture 16.

[0026] The objective lens control unit 37 is connected to the objective lens 17. The objective lens control unit 37 controls the objective lens 17 and adjusts the z position of the objective lens 17, thereby refracting the multiple beams MB-1 to MB-n through the objective lens 17 and directing them onto the inspection object OB. The objective lens 17 adjusts the focus of each beam MB that has passed through a hole in the center of the limiting aperture 16 onto the surface of the inspection object OB. The multiple beams MB-1 to MB-n are irradiated onto multiple inspection regions of the inspection object OB.

[0027] The deflector control unit 38 is connected to the deflector 18. The deflector control unit 38 controls the deflector 18 to deflect secondary electrons generated from the inspection object OB and guide them to the detector 19. The deflector 18 deflects, toward the detector 18, a plurality of secondary beams SE-1 to SE-n that are generated as a result of the plurality of beams MB-1 to MB-n being incident on the surface of the inspection object OB.

[0028] The signal processing unit 39 is connected to the detector 19. The detector 19 detects the amount of secondary electrons in a plurality of inspection regions generated by the incidence of a plurality of beams MB-1 to MB-n on the surface of the inspection object OB, and sends detection signals of the plurality of inspection regions to the signal processing unit 39. The signal processing unit 39 processes the detection signals of the plurality of inspection regions and generates image signals of the plurality of inspection regions.

[0029] The image generating unit 41 is connected to the signal processing unit 39. The image generating unit 41 receives image signals of the multiple inspection areas from the signal processing unit 39, and generates image data corresponding to the image signals of the multiple inspection areas. The image generating unit 41 supplies the image data to the control computer 3. The image data indicates an image (inspection image) of a pattern formed on the surface of the inspection object OB. The inspection image is displayed on the display device 8 via the control computer 3, and is also stored in the storage device 7.

[0030] The input device 9 is an interface for inputting information such as design data, the material of the object under inspection OB, beam conditions, the coordinate position of the inspection area, various threshold values ​​for inspection, and the like, into the control computer 3.

[0031] The storage device 7 stores information such as beam conditions, coordinate positions of the inspection area, and various thresholds for inspection input from the input device 9. The storage device 7 also stores the inspection results together with an image (inspection image) of the pattern formed on the surface of the inspection object OB.

[0032] The pattern information storage device 4 stores information such as design data, drawing data, and the structure and material of the inspection object OB. The pattern information storage device 4 also stores pattern information of a plurality of inspection regions generated based on the design data. The pattern information of a plurality of inspection regions will be described later.

[0033] The material information storage device 5 stores material information on the material of the inspection object OB. When the inspection object OB is a master for nanoimprinting, the material may include a light-transmitting insulator such as glass, quartz, etc. When the inspection object OB is a device substrate, the material may include a semiconductor such as silicon.

[0034] The pre-irradiation map storage device 6 stores a pre-irradiation map for each irradiation region RR. The pre-irradiation map is information in which the irradiation amount is mapped for each of a plurality of inspection regions. The pre-irradiation map storage device 6 may store information in which the pre-irradiation map and the position information of the irradiation region RR are associated with each other for the irradiation region RR at a plurality of positions. The pre-irradiation map indicates the distribution of the irradiation amount of a plurality of beams (multi-beams) corresponding to a plurality of inspection regions.

[0035] Next, a plurality of inspection regions in the inspection object OB will be described with reference to Fig. 2. Fig. 2 is a diagram showing a plurality of beams and a plurality of inspection regions.

[0036] Fig. 2(a) is a plan view showing an example of a pattern region PR in which a pattern is formed on an inspection object OB. The inspection object OB may be rectangular or circular in the xy plane view. Fig. 2(a) illustrates a case where the inspection object OB is rectangular.

[0037] The pattern region PR is a region included inside the surface OBa of the inspection object OB in the xy-plane view. The pattern region PR may be rectangular or circular. When the inspection object OB is a master for nanoimprinting, the pattern region PR may be a region on the surface OBa that is raised like a pedestal.

[0038] FIG. 2(b) is a plan view showing the configuration within the pattern region PR, and is an enlarged plan view of FIG. 2(a) shown in FIG. 2(a).

[0039] The pattern region PR includes a plurality of inspection stripe regions SR-1 to SR-k (k is any integer equal to or greater than 2). The plurality of inspection stripe regions SR-1 to SR-k are obtained by dividing the pattern region PR into stripes, for example, by the y-directional width of the irradiation region RR. The irradiation region RR indicates an area that can be irradiated with a single multi-beam (i.e., a plurality of beams MB-1 to MB-n). Each inspection stripe region SR extends along the x-direction. When the pattern region PR is rectangular in the xy-plane view, the x-directional length of each inspection stripe region SR may be uniform.

[0040] The irradiation area RR is defined as (x-direction size obtained by multiplying the inter-beam pitch in the x direction of the multi-beams on the surface of the inspection object OB by the number of beams in the x direction) x (y-direction size obtained by multiplying the inter-beam pitch in the y direction of the multi-beams on the surface of the inspection object OB by the number of beams in the y direction). The example in Fig. 2 shows a case where the width (y-direction size) of the inspection stripe area is the same size as the y-direction size of the irradiation area. However, this is not limited to this.

[0041] The width (y-direction size) of the stripe region may be larger than the y-direction size of the irradiation region. For example, it is preferable that the width (y-direction size) of the inspection stripe region is set to a natural number multiple of the y-direction size of the irradiation region.

[0042] In this embodiment, the inspection apparatus 1 scans (performs a scanning operation) the irradiation region RR in the x direction for each inspection stripe region SR, and acquires an image for each irradiation region RR.

[0043] As shown in FIG. 2(c), the irradiation region RR includes a plurality of inspection regions DR(1,1) to DR(5,5). Each inspection region DR is obtained by dividing the irradiation region RR into a plurality of regions, and is also called a sub-irradiation region. FIG. 2(c) shows a plurality of inspection regions DR(1,1) to DR(5,5) in the irradiation region RR. The plurality of inspection regions DR(1,1) to DR(5,5) can be arranged in the x and y directions within the irradiation region RR. FIG. 2(c) illustrates the case where the multi-beam includes 25 beams MB-1 to MB-25 and is arranged in 5 rows and 5 columns.

[0044] As shown in Fig. 2(c), each beam MB constituting the multi-beam is responsible for a different inspection region DR and scans a location corresponding to the same position within the inspection region DR that it is responsible for. A circle indicates one beam BM of the group of beams constituting the multi-beam.

[0045] The beam BM is raster scanned in each inspection region DR. In the inspection region DR, the beam BM is scanned in the +y direction from positions on the -x and -y sides, and when it reaches the +y end of the inspection region DR, it is deflected to the -y end of the inspection region DR while shifting in the +x direction. The beam BM is then scanned in the +y direction. The inspection device 1 repeats this operation, sequentially irradiating each inspection region DR with one beam BM.

[0046] The inspection apparatus 1 shown in Fig. 1 performs preliminary irradiation of an inspection object OB prior to irradiation of a plurality of beams MB-1 to MB-n for inspection. For example, the inspection apparatus 1 acquires design data of an irradiation region RR. The design data of the irradiation region RR may be design data as shown in Fig. 3(a).

[0047] 3(a) illustrates an example of design data for the irradiation region RR. The design data includes a pattern to be formed on the inspection object OB. When the inspection object OB is a master for nanoimprinting, the pattern is formed as a concave-convex pattern in the pattern region PR. When the inspection object OB is a device substrate, the pattern is formed as a wiring pattern or a groove / hole pattern in the pattern region PR.

[0048] The inspection device 1 shown in Fig. 1 obtains pattern information for a plurality of inspection regions DR(1,1) to DR(5,5) based on design data for an irradiation region RR. The inspection device 1 obtains preliminary irradiation amounts corresponding to the plurality of inspection regions DR(1,1) to DR(5,5) based on the obtained pattern information for the plurality of inspection regions DR(1,1) to DR(5,5). As shown in Fig. 3(b), the inspection device 1 may obtain preliminary irradiation amounts (pre-irradiation amounts) for the plurality of inspection regions DR(1,1) to DR(5,5) so that the charge amounts are uniform among the plurality of inspection regions DR(1,1) to DR(5,5).

[0049] Fig. 3(b) is a diagram showing a plurality of inspection regions DR(1,1) to DR(5,5) and their design data superimposed on each other. In Fig. 3(b), the pre-irradiation amount of each inspection region DR is indicated by the size of the circle and the shade of the color of the circle. The larger the circle, the greater the pre-irradiation amount, and the smaller the circle, the less the pre-irradiation amount. The darker the circle, the greater the pre-irradiation amount, and the lighter the circle, the less the pre-irradiation amount.

[0050] For example, if the object to be inspected OB is a master for nanoimprinting, the substrate used for the master, such as glass or quartz, accumulates charge when irradiated with a beam during inspection, causing changes in the brightness and contrast of the inspection image. Moreover, the charging state changes depending on the material of the object to be inspected OB, the size of the pattern, the coverage of the pattern, the distance between patterns, etc.

[0051] Therefore, the inspection device 1 divides the design data of the irradiation region RR shown in Fig. 3(a) into design data of a plurality of inspection regions DR(1,1) to DR(5,5) as shown in Fig. 3(b). The inspection device 1 obtains pattern information for each design data of the inspection region DR after division, determines a preliminary irradiation amount (pre-irradiation amount) according to the pattern information, and stores it in the pattern information storage device 4. The pattern information may include at least one of the pattern size, the pattern coverage, and the pattern distance.

[0052] For example, when the inspection object OB is an original plate for nanoimprinting, the smaller the size of the concave and convex patterns in the pattern region PR, the less likely they are to be charged, and the larger the size of the pattern, the more likely they are to be charged. The size of the pattern may be the average width in the xy directions of the concave pattern, or the average width in the xy directions of the convex pattern. The size of the pattern may be the minimum width in the xy directions of the concave pattern, or the minimum width in the xy directions of the convex pattern. The size of the pattern may be the maximum width in the xy directions of the concave pattern, or the maximum width in the xy directions of the convex pattern.

[0053] The inspection device 1 may obtain the size of each pattern of the inspection area DR after division, and determine the pre-irradiation amount according to the size of the pattern. When determining the pre-irradiation amount in three stages, the inspection device 1 may determine the pre-irradiation amount to be "large" if the size of the pattern of the inspection area DR is less than Sth1. The inspection device 1 may determine the pre-irradiation amount to be "medium" if the size of the pattern of the inspection area DR is equal to or greater than Sth1 and less than Sth2 (>Sth1). The inspection device 1 may determine the pre-irradiation amount to be "small" if the size of the pattern of the inspection area DR is equal to or greater than Sth2.

[0054] Alternatively, when the inspection object OB is a master for nanoimprinting, the concave and convex patterns in the pattern region PR tend to be less likely to be charged when their pattern coverage is small, and more likely to be charged when their pattern coverage is large. The pattern coverage may be the ratio of the area of ​​the concave pattern to the area of ​​the inspection region DR, the ratio of the area of ​​the convex pattern to the area of ​​the inspection region DR, or the ratio of the area of ​​the boundary between the concave pattern and the convex pattern to the area of ​​the inspection region DR.

[0055] The inspection device 1 may obtain the coverage rate for each pattern of the divided inspection area DR, and determine the pre-irradiation amount according to the coverage rate of the pattern. When determining the pre-irradiation amount in three stages, the inspection device 1 may determine the pre-irradiation amount to be "large" if the coverage rate of the pattern of the inspection area DR is less than Cth1. The inspection device 1 may determine the pre-irradiation amount to be "medium" if the coverage rate of the pattern of the inspection area DR is equal to or greater than Cth1 and less than Cth2 (>Cth1). The inspection device 1 may determine the pre-irradiation amount to be "small" if the coverage rate of the pattern of the inspection area DR is equal to or greater than Cth2.

[0056] Alternatively, when the inspection object OB is a master for nanoimprinting, the concave patterns and the convex patterns in the pattern region PR tend to be less likely to be charged when the distance between the patterns is shorter, and more likely to be charged when the distance between the patterns is longer. The distance between the patterns may be the average distance in the xy directions between the concave patterns, the average distance in the xy directions between the convex patterns, or the average distance in the xy directions between the boundary portions of the concave patterns and the convex patterns.

[0057] The inspection device 1 may obtain the inter-pattern distance for each pattern in the divided inspection area DR, and determine the pre-irradiation amount according to the inter-pattern distance. When determining the pre-irradiation amount in three stages, the inspection device 1 may determine the pre-irradiation amount to be "large" if the inter-pattern distance in the inspection area DR is less than Dth1. The inspection device 1 may determine the pre-irradiation amount to be "medium" if the inter-pattern distance in the inspection area DR is equal to or greater than Dth1 and less than Dth2 (>Dth1). The inspection device 1 may determine the pre-irradiation amount to be "small" if the inter-pattern distance in the inspection area DR is equal to or greater than Dth2.

[0058] Furthermore, the inspection device 1 may adjust the dose of each inspection region DR according to material information of the inspection object OB. It is assumed that the material of the inspection object OB has an emission rate of secondary electrons K times higher than that of primary electrons compared to a reference material (e.g., glass). In this case, the inspection device 1 may adjust the dose of each inspection region DR according to the following formulas 1 to 3. (Pre-irradiation dose of inspection area DR for "large" irradiation dose) = ("large" irradiation dose) × K Formula 1 (Pre-irradiation dose of inspection area DR with "medium" irradiation dose) = ("medium" irradiation dose) × K Equation 2 (Pre-irradiation dose of the inspection area DR for "small" irradiation dose) = ("small" irradiation dose) × K Equation 3

[0059] For example, the material information may include information about the value of K. The inspection device 1 may read out the material information from the material information storage device 5, and adjust the irradiation amount of each inspection region DR according to the read-out material information using formulas 1 to 3.

[0060] After determining the pre-irradiation amount for each inspection region DR, the inspection device 1 creates a pre-irradiation map as shown in Fig. 3(b) and stores it in the pre-irradiation map storage device 6. In the preliminary irradiation, the inspection device 1 irradiates the multiple inspection regions DR with multiple beams MB-1 to MB-n at pre-irradiation amounts according to the pre-irradiation map.

[0061] In Fig. 3(b), the pre-irradiation amount is expressed in three stages, large, medium, and small, but is not limited to this. The pre-irradiation map may be created with more stages of pre-irradiation amount, or may be created with two stages of pre-irradiation amount.

[0062] The pre-irradiation amount can be adjusted as shown in Fig. 4. Fig. 4 is a diagram showing the adjustment operation of the pre-irradiation amount. In the inspection device 1 shown in Fig. 1, the blanking aperture control unit 34 allows the blanking aperture 14 to arbitrarily change the scanning trajectory and scanning speed of each beam MB within the inspection region DR.

[0063] As shown in Figures 4(a) to 4(c), the dose may be adjusted by changing the scan density in the raster scan. The higher the scan density, the higher the dose. Figures 4(a), 4(b), and 4(c) respectively illustrate the case where the scan in the y direction is performed on an orbit of 9 rows, 5 rows, and 3 rows aligned in the x direction. Figures 4(a), 4(b), and 4(c) respectively show high, medium, and small scan densities, which correspond to the high, medium, and small doses of irradiation in Figure 3(b).

[0064] As shown in FIG. 4(d) to FIG. 4(f), the dose may be adjusted by changing the scanning speed in the raster scan. The higher the scanning speed, the higher the dose. FIG. 4(d), FIG. 4(e), and FIG. 4(f) respectively show examples of scanning in the y direction at high, medium, and low speeds, as indicated by the lengths of the arrows. FIG. 4(d), FIG. 4(e), and FIG. 4(f) show scanning densities of large, medium, and small, respectively, which correspond to the large, medium, and small doses of irradiation in FIG. 3(b). The dose may be adjusted by changing the scanning density and speed in the raster scan by combining the adjustments shown in FIG. 4(a) to FIG. 4(c) and the adjustments shown in FIG. 4(d) to FIG. 4(f).

[0065] Next, the procedures for preliminary irradiation (pre-irradiation) of the pattern area PR and irradiation / image acquisition for inspection will be described. The procedures can be roughly classified into two. The first is an implementation procedure for scanning in units of an inspection stripe area SR as shown in Fig. 5, and the second is an implementation procedure for scanning each of the upper half area and the lower half area obtained by dividing the inspection stripe area SR in the y direction as shown in Fig. 6. Figs. 5 and 6 are each a diagram showing the operation of the inspection apparatus 1.

[0066] In the implementation procedure of FIG. 5, the inspection device 1 performs pre-irradiation on one inspection stripe region SR while scanning the irradiation region RR in a first direction, and performs irradiation and image acquisition for inspection on the same inspection stripe region SR while scanning the irradiation region RR in a second direction. The first direction is along the x direction. The second direction is along the x direction, which is the opposite direction to the first direction.

[0067] For example, as shown by the dotted arrow in Fig. 5(a), the inspection device 1 performs pre-irradiation while scanning the irradiation region RR from the position of the -x side end in the +x direction in the inspection stripe region SR-1. Specifically, the inspection device 1 positions the irradiation region RR at the -x side end in the inspection stripe region SR-1, and performs pre-irradiation with the respective pre-irradiation doses on each inspection region DR in the irradiation region RR. When the pre-irradiation is completed, the inspection device 1 moves the irradiation region RR to an adjacent position on the +x side in the inspection stripe region SR-1, and performs pre-irradiation with the respective pre-irradiation doses on each inspection region DR in the irradiation region RR. As shown by the dotted arrow, the inspection device 1 alternately repeats the execution of pre-irradiation on the irradiation region RR and the movement of the irradiation region RR to the adjacent position up to the position of the +x side end.

[0068] When the pre-irradiation at the +x end position of the inspection stripe region SR-1 is completed, the inspection device 1 performs inspection irradiation and image acquisition while scanning the irradiation region RR in the -x direction, as shown by the solid arrow in FIG. 5(b). Specifically, the inspection device 1 performs inspection irradiation and image acquisition, for example, with a uniform irradiation amount, for each inspection region DR in the irradiation region RR while maintaining the irradiation region RR at the +x end position. When the inspection device 1 completes the inspection irradiation at the +x end position, it moves the irradiation region RR to a position adjacent to the -x side in the inspection stripe region SR-1, and performs inspection irradiation and image acquisition, for example, with a uniform irradiation amount, for each inspection region DR in the irradiation region RR. The inspection device 1 alternately repeats the execution of inspection irradiation and image acquisition for the irradiation region RR and the movement of the irradiation region RR to an adjacent position, as shown by the solid arrow.

[0069] When pre-irradiation at the -x end position of the inspection stripe region SR-1 is completed, the inspection apparatus 1 moves the irradiation region RR in the +y direction and positions the irradiation region RR at the -x end of the inspection stripe region SR-2.

[0070] As indicated by the dotted arrow in FIG. 5(c), the inspection device 1 performs pre-irradiation while scanning the irradiation region RR in the inspection stripe region SR-2 from the position of the -x side end in the +x direction.

[0071] When pre-irradiation at the +x end position of the inspection stripe region SR-2 is completed, the inspection device 1 performs irradiation and image acquisition for inspection while scanning the irradiation region RR in the -x direction within the inspection stripe region SR-2, as shown by the solid arrow in Figure 5 (d).

[0072] In the implementation procedure of FIG. 6, the inspection stripe region SR is divided into upper and lower halves (halves in the y direction), and the upper half (+y side) is a half stripe region SRU and the lower half (-y side) is a half stripe region SRL. The upper half of the irradiation region RR is RRU, and the lower half of the irradiation region RR is RRL. The inspection device 1 performs pre-irradiation while scanning the half region RRU in the first direction within the half stripe region SRU, and performs irradiation and image acquisition for inspection while scanning the half region RRL in the first direction within the half stripe region SRL. The inspection device 1 moves in the +y direction by the y direction width of the half stripe region. The inspection device 1 performs pre-irradiation while scanning the half region RRU in the second direction within the half stripe region SRL, and performs irradiation and image acquisition for inspection while scanning the half region RRL in the second direction within the half stripe region SRU.

[0073] For example, the inspection device 1 performs pre-irradiation while scanning the half region RRU in the half stripe region SRU-1 from the position of the -x end in the +x direction, as shown by the dotted arrow in Fig. 6(a). At the same time, the inspection device 1 performs pre-irradiation, irradiation for inspection, and image acquisition while scanning the half region RRL in the half stripe region SRL-1 from the position of the -x end in the +x direction, as shown by the dotted arrow and solid arrow in Fig. 6(a).

[0074] When pre-irradiation at the +x end of half stripe region SRU-1 is completed and image acquisition at the +x end of half stripe region SRL-1 is completed, inspection device 1 moves half region RRU in the +y direction to position it at the +x end of half stripe region SRL-2, and moves half region RRL in the +y direction to position it at the +x end of half stripe region SRU-1.

[0075] The inspection device 1 performs pre-irradiation while scanning the half region RRU in the half stripe region SRL-2 from the position on the +x side end in the -x direction, as shown by the dotted arrow in Fig. 6(b). At the same time, the inspection device 1 performs irradiation and image acquisition for inspection while scanning the half region RRL in the half stripe region SRU-1 from the position on the +x side end in the -x direction, as shown by the solid arrow in Fig. 6(b).

[0076] When pre-irradiation at the -x end of half stripe region SRL-2 is completed and image acquisition at the -x end of half stripe region SRU-1 is completed, inspection device 1 moves half region RRU in the +y direction to position it at the -x end of half stripe region SRU-2, and moves half region RRL in the +y direction to position it at the -x end of half stripe region SRL-2.

[0077] The inspection device 1 performs pre-irradiation while scanning the half region RRU in the half stripe region SRU-2 from the position of the -x end in the +x direction, as shown by the dotted arrow in Fig. 6(c). At the same time, the inspection device 1 performs irradiation and image acquisition for inspection while scanning the half region RRL in the half stripe region SRL-2 from the position of the -x end in the +x direction, as shown by the solid arrow in Fig. 6(c).

[0078] When pre-irradiation at the +x end of half stripe region SRU-2 is completed and image acquisition at the +x end of half stripe region SRL-2 is completed, inspection device 1 moves half region RRU in the +y direction to position it at the +x end of half stripe region SRL-3, and moves half region RRL in the +y direction to position it at the +x end of half stripe region SRU-2.

[0079] The inspection device 1 performs pre-irradiation while scanning the half region RRU in the half stripe region SRL-3 from the position on the +x side end in the -x direction, as shown by the dotted arrow in Fig. 6(d). At the same time, the inspection device 1 performs irradiation and image acquisition for inspection while scanning the half region RRL in the half stripe region SRU-2 from the position on the +x side end in the -x direction, as shown by the solid arrow in Fig. 6(d).

[0080] Next, the flow of operations of the inspection device 1 will be described with reference to Fig. 7. Fig. 7 is a flowchart showing the operations of the inspection device 1. Fig. 7 shows an example of the procedure of a multi-beam inspection method.

[0081] The inspection apparatus 1 reads design data of the pattern area PR from the pattern information storage device 4 into the control computer 3 (S1). The design data may be two-dimensional design data (e.g., layout design data). The inspection apparatus 1 reads material information of the inspection object OB from the material information storage device 5 into the control computer 3 (S2). The inspection apparatus 1 creates pre-irradiation maps of multiple inspection areas DR based on the design data read in S1 and the material information read in S2 (S3) and stores the maps in the pre-irradiation map storage device 6.

[0082] For example, the inspection apparatus 1 divides the design data of the pattern region PR into design data of a plurality of inspection stripe regions SR, and divides the design data of each inspection stripe region SR into design data of irradiation regions RR at a plurality of positions. The inspection apparatus 1 divides the design data of the irradiation region RR at each position into design data of a plurality of inspection regions DR. The inspection apparatus 1 obtains pattern information of the plurality of inspection regions DR based on the design data of the plurality of inspection regions DR. The pattern information may include at least one of the size of the pattern, the coverage rate of the pattern, and the distance between the patterns. The inspection apparatus 1 obtains the doses of the plurality of beams MB corresponding to the plurality of inspection regions based on the pattern information of the plurality of inspection regions DR. The inspection apparatus 1 may adjust the dose of each inspection region DR according to material information of the inspection object OB. The inspection apparatus 1 creates a pre-irradiation map of the plurality of inspection regions DR according to the dose of each inspection region DR.

[0083] When it is time to perform pre-irradiation, the inspection device 1 reads the pre-irradiation map from the pre-irradiation map storage device 6. The inspection device 1 determines the implementation procedure of pre-irradiation and irradiation / image acquisition for inspection in the pattern area PR based on the pre-irradiation map (S4). For example, the inspection device 1 may determine the implementation procedure of pre-irradiation and irradiation / image acquisition for inspection in the pattern area PR to be the implementation procedure shown in FIG. 5 or the implementation procedure shown in FIG. 6. The inspection device 1 performs pre-irradiation and irradiation / image acquisition for inspection of the multiple inspection areas DR according to the implementation procedure determined in S4 (S5). At this time, when focusing on the irradiation area RR at the same position, the inspection device 1 preliminarily irradiates the multiple inspection areas DR with the multiple beams MB at the irradiation amount obtained for each. The inspection device 1 irradiates the multiple inspection areas DR with the multiple beams MB in a state in which the preliminary irradiation (pre-irradiation) has been performed. The inspection device 1 generates images of the multiple inspection areas DR irradiated with the multiple beams MB.

[0084] The inspection device 1 performs inspection (S6). For example, the inspection device 1 may generate an overall image by synthesizing the images of each inspection region DR acquired in S5 for the entire pattern DR, and perform inspection using the overall image. Alternatively, the inspection device 1 may generate a stripe image by synthesizing the images of each inspection region DR acquired in S5 for an inspection stripe region SR (see FIG. 5), and perform inspection for each inspection stripe region SR using the stripe image. Alternatively, the inspection device 1 may generate an irradiation region image by synthesizing the images of each inspection region DR acquired in S5 for an irradiation region RR at each position (see FIG. 5 and FIG. 6), and perform inspection for each irradiation region RR at each position using the irradiation region image.

[0085] As described above, in the embodiment, the inspection device 1 determines the preliminary doses corresponding to the multiple inspection areas based on the pattern information of the multiple inspection areas. The inspection device 1 preliminarily irradiates each of the multiple inspection areas in the inspection object OB with the beam MB at the determined dose. After that, the inspection device 1 irradiates the multiple inspection areas with the multiple inspection beams MB-1 to MB-n in a state where the preliminary irradiation has been performed. This allows the primary electrons to be irradiated by the inspection beam irradiation in a state where the emission rate of the secondary electrons relative to the primary electrons in the multiple inspection areas is equalized by the preliminary beam irradiation. As a result, the emission rate of the secondary electrons for inspection can be made to more appropriately reflect the surface state of the inspection object, so that the variation in brightness or contrast for each inspection image can be suppressed, and the inspection accuracy by the inspection device 1 can be improved.

[0086] As shown in Fig. 8, the inspection device 1a may not generate the pre-irradiation map but may obtain it from an external pre-irradiation map generating system 100. Fig. 8 is a diagram showing the configuration of an inspection device 1a according to a modified example of the embodiment.

[0087] The inspection device 1a omits the pattern information storage device 4, the material information storage device 5, and the pre-irradiation map storage device 6 (see FIG. 1), and further includes an interface (I / F) unit 9a. The pre-irradiation map generating system 100 includes a control device 103, a pattern information storage device 104, a material information storage device 105, a pre-irradiation map storage device 106, and an interface (I / F) unit 109a. The pre-irradiation map generating system 100 may be realized, for example, as a computer.

[0088] For example, when the I / F unit 9a and the I / F unit 109a are connected by a communication line, the inspection device 1a transmits a pre-irradiation map creation request from the I / F unit 9a via the communication line to the pre-irradiation map generating system 100. In the pre-irradiation map generating system 100, when the I / F unit 9a receives the pre-irradiation map creation request, the control unit 103 reads design data from the pattern information storage device 4 and reads material information of the inspection object OB from the material information storage device 5 to the control computer 3. The control unit 103 creates pre-irradiation maps of multiple inspection regions DR based on the read design data and the read material information, and stores the maps in the pre-irradiation map storage device 106.

[0089] When the timing for performing pre-irradiation arrives, the inspection device 1a transmits a pre-irradiation map acquisition request from the I / F unit 9a via a communication line to the pre-irradiation map generation system 100. When the I / F unit 9a receives the pre-irradiation map creation request in the pre-irradiation map generation system 100, the control unit 103 reads out the pre-irradiation map from the pre-irradiation map storage device 106 and transmits the pre-irradiation map from the I / F unit 109a via a communication line to the inspection device 1a. When the inspection device 1a receives the pre-irradiation map at the I / F unit 9a, it performs the processes of S5 and S6 in FIG. 7.

[0090] Alternatively, when the I / F unit 9a and the I / F unit 109a are not connected by a communication line, the pre-irradiation map generating system 100 may receive a pre-irradiation map creation request via the I / F unit 109a. When the pre-irradiation map creation request is received, the control unit 103 reads design data from the pattern information storage device 4, and reads material information of the inspection object OB from the material information storage device 5 to the control computer 3. The control unit 103 creates pre-irradiation maps of multiple inspection regions DR based on the read design data and the read material information, and stores the maps in the pre-irradiation map storage device 106.

[0091] When the timing for performing pre-irradiation arrives, the inspection device 1a displays information such as a message indicating that pre-irradiation should be performed on the display device 8 to notify the user. In response to this notification, the pre-irradiation map generating system 100 may have an external storage medium (not shown) connected to the I / F unit 109a and a pre-irradiation map acquisition request input via the I / F unit 109a. When the pre-irradiation map acquisition request is input, the control unit 103 reads the pre-irradiation map from the pre-irradiation map storage device 106 and stores it in the external storage medium via the I / F unit 109a. In response to this storage, the inspection device 1a connects the external storage medium to the I / F unit 9a and inputs the pre-irradiation map from the external storage medium via the I / F unit 9a. When the pre-irradiation map is input via the I / F unit 9a, the inspection device 1a performs the processes of S5 and S6 in FIG. 7.

[0092] In this way, in the inspection device 1a, the pattern information storage device 4, the material information storage device 5, and the pre-irradiation map storage device 6 are omitted in accordance with the fact that the pre-irradiation map is not generated but is acquired from the external pre-irradiation map generating system 100. This allows the configuration of the inspection device 1a to be simplified and the cost of the inspection device 1a to be reduced.

[0093] In the above embodiment, the object to be inspected OB is an original (template) for nanoimprinting, but the present embodiment can also be applied to the inspection of EUV masks and actual device substrates. In this case, the positive charge state where the inspection image becomes bright is not necessarily the best, and the point where the charge changes to negative charge where the inspection image becomes dark is the boundary between positive and negative charging. In other words, pre-irradiation may be performed so that the charge becomes weak.

[0094] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0095] 1,1a inspection device, 3 control computer, 10 electron lens column, 11 electron gun, 13 shaping aperture, 14 blanking aperture, 41 image generation unit.

Claims

1. a control unit that determines irradiation doses of a plurality of first beams corresponding to each of a plurality of inspection regions on an object to be inspected, the plurality of inspection regions being arranged in a first direction and a second direction, based on pattern information of the plurality of inspection regions in the object to be inspected; an irradiation unit that preliminarily irradiates the plurality of first beams to the plurality of inspection regions at irradiation amounts determined respectively, and irradiates the plurality of second beams to the plurality of inspection regions in a state in which the preliminary irradiation has been performed; a generation unit that generates images of the plurality of inspection regions irradiated with the plurality of second beams; Equipped with The control unit determines, for each of the plurality of inspection regions, a larger irradiation amount of the first beam corresponding to the inspection region as a pattern size or a distance between patterns becomes smaller. Inspection equipment.

2. The control unit determines, for each of the plurality of inspection regions, a stepwise increase in the irradiation amount of the first beam corresponding to the inspection region as the pattern size or the distance between the patterns becomes smaller.

2. The inspection device according to claim 1.

3. The control unit determines the irradiation amount of the first beam corresponding to the first inspection area to be a first irradiation amount based on the fact that a pattern size of a first inspection area among the multiple inspection areas is a first size or the inter-pattern distance of the first inspection area is a first distance, and determines the irradiation amount of the first beam corresponding to the second inspection area to be a second irradiation amount greater than the first irradiation amount based on the fact that a pattern size of a second inspection area among the multiple inspection areas is a second size smaller than the first size or the inter-pattern distance of the second inspection area is a second distance shorter than the first distance; The irradiation unit irradiates the first inspection region with the first beam at the first irradiation amount, and irradiates the second inspection region with the first beam at the second irradiation amount.

3. The inspection device according to claim 2.

4. The control unit detects defects of the inspection object from images of the plurality of inspection areas.

2. The inspection device according to claim 1.

5. The pattern information includes at least one of a pattern size, a pattern coverage rate, and a pattern distance.

2. The inspection device according to claim 1.

6. The irradiation unit includes: A generating unit that generates a charged particle beam; a splitting unit that splits the generated charged particle beam into the plurality of first beams or the plurality of second beams; an adjustment unit that adjusts the irradiation amount of each of the divided first beams or the divided second beams with respect to the multiple inspection regions; having The control unit is The driving of the generating unit, the dividing unit, and the adjusting unit is controlled so that the plurality of first beams are preliminarily irradiated to the plurality of inspection regions at the irradiation amounts respectively determined, and the plurality of second beams are irradiated to the plurality of inspection regions in a state in which the preliminarily irradiation has been performed.

2. The inspection device according to claim 1.

7. The adjustment unit is By adjusting a raster scan speed of each of the plurality of first beams within a corresponding inspection region, an irradiation amount of each of the plurality of first beams with respect to the plurality of inspection regions is adjusted.

7. The inspection device according to claim 6.

8. The adjustment unit is The raster scan density of each of the plurality of first beams is adjusted within the corresponding inspection area to adjust the irradiation amount of each of the plurality of first beams with respect to the plurality of inspection areas.

7. The inspection apparatus according to claim 6.

9. acquiring pattern information of a plurality of inspection areas arranged in a first direction and a second direction for an object to be inspected, the inspection areas being divided into a plurality of irradiation areas; determining irradiation doses of a plurality of first beams corresponding to each of the plurality of inspection regions based on pattern information of the plurality of inspection regions; Preliminarily irradiating the inspection areas with the first beams at respective determined irradiation doses; irradiating the inspection areas with a plurality of second beams after the preliminary irradiation; generating images of the plurality of inspection areas illuminated with the plurality of second beams; Including, The obtaining includes: determining, for each of the plurality of inspection regions, a larger irradiation amount of the first beam corresponding to the inspection region as a size of a pattern or a distance between patterns becomes smaller. Testing method.

10. A preliminary dose of each of the plurality of first beams on the plurality of inspection areas is adjusted by changing a raster scan speed of each of the plurality of first beams within a corresponding inspection area. The inspection method according to claim 9.

11. A preliminary dose of each of the plurality of first beams on the plurality of inspection areas is adjusted by changing a density of a raster scan of each of the plurality of first beams within a corresponding inspection area. The inspection method according to claim 9.

12. and detecting defects in the inspection object from images of the plurality of inspection areas. The inspection method according to claim 9.

Images