Inspection apparatus and inspection method

Abstract

This invention relates to an inspection apparatus and an inspection method. According to one embodiment, an inspection apparatus comprising a control unit, an irradiation unit, and a generation unit is provided. The control unit calculates the irradiation amount of multiple first beams based on pattern information of multiple inspection areas in an object to be inspected. The object to be inspected includes multiple inspection areas. The multiple first beams correspond to the multiple inspection areas. The irradiation unit preemptively irradiates the multiple inspection areas with the calculated irradiation amount using the multiple first beams. While preemptively irradiating, the irradiation unit irradiates the multiple inspection areas with multiple second beams. The generation unit generates an image of the multiple inspection areas irradiated by the multiple second beams.

Description

[0001] [Citation of relevant applications]

[0002] This application is based on and seeks the benefit of priority of Japanese Patent Application No. 2021-150452, filed earlier on September 15, 2021, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This embodiment relates to an inspection device and an inspection method. Background Technology

[0004] In inspection devices such as electron microscopes, specific inspections are performed by generating images of the object being inspected by irradiating it with beams of charged particles. There is a desire to improve the precision of these inspections. Summary of the Invention

[0005] One embodiment relates to an inspection apparatus and inspection method that can easily improve inspection accuracy.

[0006] According to one embodiment, an inspection apparatus is provided, comprising a control unit, an irradiation unit, and a generation unit. The control unit calculates the irradiation amount of multiple first beams based on pattern information of multiple inspection areas in an object to be inspected. The object to be inspected includes multiple inspection areas. The multiple first beams correspond to the multiple inspection areas. The irradiation unit pre-irradiates the multiple inspection areas with the calculated irradiation amount using the multiple first beams. While pre-irradiating, the irradiation unit irradiates the multiple inspection areas with multiple second beams. The generation unit generates an image of the multiple inspection areas irradiated by the multiple second beams.

[0007] Based on the above configuration, an inspection device and inspection method that can easily improve inspection accuracy can be provided. Attached Figure Description

[0008] Figure 1 This is a diagram showing the configuration of the inspection device according to the implementation method.

[0009] Figure 2 (a) to (c) are diagrams showing the multiple beams and multiple inspection areas of the implementation method.

[0010] Figure 3 (a) and (b) are diagrams showing pattern information and irradiation levels in multiple inspection areas according to the implementation method.

[0011] Figure 4 (a) to (f) are diagrams showing the adjustment action of the irradiation amount in the implementation method.

[0012] Figure 5 (a) to (d) are diagrams showing the operation of the inspection device in the embodiment.

[0013] Figure 6 (a) to (d) are diagrams showing the operation of the inspection device in the embodiment.

[0014] Figure 7 This is a flowchart illustrating the operation of the inspection device in the implementation method.

[0015] Figure 8 This is a diagram showing the configuration of an inspection device for a variation of the implementation method. Detailed Implementation

[0016] The inspection apparatus of the embodiment will be described in detail below with reference to the accompanying drawings. However, the present invention is not limited to this embodiment.

[0017] (Implementation Method) The inspection device in this implementation method is a multi-beam inspection device, which can be used as follows: Figure 1 It is constructed as shown. Figure 1 This is a diagram showing the configuration of the inspection device 1. Hereinafter, the vertical direction will be defined as the x-direction, and the two directions that are orthogonal to each other in the plane perpendicular to the z-direction will be defined as the x-direction and the y-direction.

[0018] Inspection device 1 splits the charged particle beam EB and irradiates multiple inspection areas of the object OB with the split beams (multi-beams) MB-1 to MB-n. n is any integer greater than 2. The inspection device acquires images of the multiple inspection areas to perform specific inspections on the object OB. The object OB can be a master for nanoimprint lithography or a device substrate for forming a device. The master for nanoimprint lithography is also called a template. Specific inspections can be to check for defects in the object OB or to check whether the size of the pattern formed on the object OB is within an appropriate range.

[0019] Before irradiating the object to be inspected OB with the multiple beams MB-1 to MB-n used for inspection, the inspection device 1 first performs preparatory irradiation on the object to be inspected OB.

[0020] For example, inspection device 1 acquires pattern information of multiple inspection areas. Based on the pattern information of the multiple inspection areas, inspection device 1 calculates the preparatory irradiation dose corresponding to each inspection area. Inspection device 1 can also calculate the preparatory irradiation dose separately to ensure that the charge levels of the multiple inspection areas are equal. Inspection device 1 preparatoryly irradiates multiple inspection areas of the object OB with beam MB at the calculated irradiation dose. Subsequently, while in the preparatory irradiation state, inspection device 1 irradiates the multiple inspection areas with multiple inspection beams MB-1 to MB-n. The irradiation doses of the multiple inspection beams MB-1 to MB-n can also be equal to each other.

[0021] Therefore, by irradiating the primary electrons with an inspection beam, the emission rate of secondary electrons relative to primary electrons in multiple inspection areas can be made equal through preparatory beam irradiation. As a result, the emission rate of secondary electrons for inspection can more accurately reflect the surface condition of the object being inspected, thus suppressing variations in brightness or contrast in each inspection image and improving the inspection accuracy of the inspection device 1.

[0022] Specifically, the inspection device 1 includes an inspection mechanism 2, a control computer 3, a pattern information storage device 4, a material information storage device 5, a pre-irradiation image 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 material information storage device 5 of the object to be inspected (OB), the pre-irradiation image storage device 6, the storage device 7, the display device 8, and the input device 9.

[0023] The inspection mechanism 2 includes an electron microscope tube 10, a sample chamber 20, an electron gun control unit 31, an illumination lens control unit 32, a forming aperture control unit 33, a blanking aperture control unit 34, a reducing 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 generation unit 41, and a stage control unit 42. The electron microscope tube 10 and the sample chamber 20 are configured to allow multiple beams (multiple beams MB-1 to MB-n) to pass through, and are also configured to allow multiple secondary beams SE-1 to SE-n to pass through.

[0024] The electron microscope tube 10 includes an electron gun 11, an illumination lens 12, a forming aperture 13, a blanking aperture 14, a reducing lens 15, a confining aperture 16, an objective lens 17, a deflector 18, and a detector 19. The electron gun 11, illumination lens 12, forming aperture 13, blanking aperture 14, reducing lens 15, confining aperture 16, objective lens 17, deflector 18, and detector 19 are respectively located within the tube wall 10a. The tube wall 10a is configured to be depressurized by a vacuum device (not shown).

[0025] The sample chamber 20 includes a stage 21 and a drive mechanism 22. The stage 21 is a plate-shaped component extending along the XY direction, on which the object to be inspected, OB, is placed. The drive mechanism 22 enables the stage 21 to move along the X, Y, and Z directions, as well as in rotational directions about the X-axis, about the Y-axis, and about the Z-axis. Furthermore, the X, Y, and Z directions associated with the drive of the stage 21 correspond to the x, y, and z directions defined above.

[0026] The control computer 3 is connected to the electron gun control unit 31, the illumination lens control unit 32, the forming aperture control unit 33, the blanking aperture control unit 34, the reducing 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 forming aperture control unit 33, the blanking aperture control unit 34, the reducing 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.

[0027] The stage control unit 42 is connected to the drive mechanism 22 within the sample chamber 20. The inspection object OB is placed on the surface of the stage 21 on the +z side. The stage control unit 42 controls the drive mechanism 22 to move the stage 21 such that multiple inspection areas in the inspection object OB correspond to the irradiation positions of multiple beams MB-1 to MB-n.

[0028] The electron gun control unit 31 controls the operation of the electron gun 11, causing it to emit a charged particle beam EB, or stopping it from emitting the charged particle beam EB. The electron gun 11 is connected to a high-voltage power supply circuit (not shown). The electron gun control unit 31 is connected to the high-voltage power supply circuit. Under the control of the electron gun control unit 31, the high-voltage power supply circuit applies an accelerating voltage and a specific bias voltage between the cathode and anode (not shown) within the electron gun 11. By applying a specific bias voltage and heating the cathode to a specific temperature by the high-voltage power supply circuit, the electron gun 11 accelerates the electron group emitted from the cathode, thereby generating and releasing the charged particle beam EB. The charged particle beam EB is, for example, an electron beam.

[0029] Along the optical axis of the principal ray of the charged particle beam EB, an illumination lens 12, a shaping aperture 13, a blanking aperture 14, a reducing lens 15, a limiting aperture 16, an objective lens 17, a deflector 18, (the object to be inspected OB), and a stage 21 are arranged in sequence. In addition, a detector 19 is arranged near the deflector 18 at a position offset from the optical axis of the principal ray.

[0030] An illumination lens control unit 32 is connected to an illumination lens 12 located within the lens barrel wall 10a. The illumination lens control unit 32 controls the illumination lens 12, adjusting its z-position, etc., thereby collimating and guiding the charged particle beam EB received by the illumination lens 12 from the electron gun 11 to the forming aperture 13. The illumination lens 12 changes the direction of the charged particle beam EB to be approximately perpendicular to the forming aperture 13, illuminating the entire forming aperture 13 with the charged particle beam EB.

[0031] A forming aperture control unit 33 is connected to the forming aperture 13. The forming aperture 13 has a structure with multiple rectangular holes. The forming aperture control unit 33 controls the forming aperture 13, and uses the forming aperture 13 to form the charged particle beam EB into a multi-beam. That is, the charged particle beam EB passes through the multiple rectangular holes in the forming aperture 13, thereby being divided into multiple beams MB-1 to MB-n. Each beam MB is, for example, an electron beam. The collection of multiple beams MB-1 to MB-n is also called a multi-beam.

[0032] The blanking aperture control unit 34 is connected to the blanking aperture 14. The blanking aperture 14 individually deflects each of the multiple beams formed through the forming aperture. The blanking aperture control unit 34 controls the blanking aperture 14 to tilt the optical axis of each beam relative to the z-direction, thereby causing the multiple beams MB-1 to MB-n to scan in multiple inspection areas.

[0033] A reducing lens control unit 35 is connected to the reducing lens 15. The reducing lens 15 reduces the beams MB-1 to MB-n that have passed through the blanking aperture 14, and changes the direction of each beam MB-1 to MB-n so that they are oriented towards the center of the limiting aperture 16. The reducing lens control unit 35 controls the reducing lens 15, adjusts the z-position of the reducing lens 15, etc., thereby causing multiple beams MB-1 to MB-n to be refracted by the reducing lens 15 and focused near the opening of the limiting aperture 16.

[0034] A limiting aperture control unit 36 ​​is connected to the limiting aperture 16. The limiting aperture control unit 36 ​​controls the limiting aperture 16, adjusts the xy position of the limiting aperture 16, etc., thereby positioning the aperture 16a of the limiting aperture 16 near the focal point of multiple beams MB-1 to MB-n. The limiting aperture 16 blocks the beams MB that have been deflected by the blanking aperture 14. On the other hand, the beams MB that have not been deflected by the blanking aperture 14 pass through the aperture 16a at the center of the limiting aperture 16.

[0035] Objective lens control unit 37 is connected to objective lens 17. Objective lens control unit 37 controls objective lens 17, adjusts the z-position of objective lens 17, etc., thereby causing multiple beams MB-1 to MB-n to be refracted by objective lens 17 and guided onto the object to be inspected OB. Objective lens 17 aligns the focal points of each beam MB passing through the central aperture of limiting aperture 16 with the surface of object to be inspected OB. Multiple beams MB-1 to MB-n illuminate multiple inspection areas in object to be inspected OB.

[0036] The deflector control unit 38 is connected to the deflector 18. The deflector control unit 38 controls the deflector 18 to deflect the secondary electrons generated on the object under inspection OB and guide them to the detector 19. The deflector 18 deflects the multiple secondary beams SE-1 to SE-n generated by multiple beams MB-1 to MB-n incident on the surface of the object under inspection OB towards the detector 18.

[0037] The signal processing unit 39 is connected to the detector 19. The detector 19 detects the secondary electron quantities of multiple inspection areas generated by multiple beams MB-1 to MB-n incident on the surface of the object to be inspected OB, and sends the detection signals of the multiple inspection areas to the signal processing unit 39. The signal processing unit 39 processes the detection signals of the multiple inspection areas to generate image signals of the multiple inspection areas.

[0038] The image generation unit 41 is connected to the signal processing unit 39. The image generation unit 41 receives image signals from 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 generation unit 41 supplies the image data to the control computer 3. The image data represents an image (inspection image) of a pattern formed on the surface of the object being inspected OB. The inspection image is displayed via the display device 8 through the control computer 3 and stored in the storage device 7.

[0039] The input device 9 is used to input design data, the material of the object to be inspected OB, beam conditions, the coordinate position of the inspection area, and various thresholds used for inspection into the interface of the control computer 3.

[0040] Storage device 7 stores information such as beam conditions, coordinate positions of the inspection area, and various thresholds used for inspection, which are input from input device 9. Storage device 7 also stores an image (inspection image) of the pattern formed on the surface of the object being inspected OB and the inspection results.

[0041] The pattern information storage device 4 stores design data, drawing data, and information such as the structure and material of the object to be inspected (OB). Furthermore, the pattern information storage device 4 stores pattern information for multiple inspection areas generated based on the design data. The pattern information for these multiple inspection areas will be explained below.

[0042] The material information storage device 5 stores material information related to the material of the object under inspection OB. When the object under inspection OB is a template for nanoimprinting, the material may include transparent insulating materials such as glass or quartz. When the object under inspection OB is a device substrate, the material may include semiconductors such as silicon.

[0043] The pre-illumination map storage device 6 stores the pre-illumination map for each irradiation area RR. The pre-illumination map is information mapping the irradiance to each of the multiple inspection areas. The pre-illumination map storage device 6 can also store information that associates the pre-illumination map with the location information of the irradiation areas RR for multiple locations. The pre-illumination map represents the distribution of irradiance from multiple beams (multi-beams) corresponding to the multiple inspection areas.

[0044] Next, use Figure 2The multiple inspection areas in the object OB are described. Figure 2 It is a diagram representing multiple beams and multiple inspection areas.

[0045] Figure 2 (a) is a top view showing an example of a patterned area PR formed in an object OB under inspection. The object OB under inspection can be rectangular or circular in the xy top view. Figure 2 (a) illustrates the case where the object OB being inspected is rectangular.

[0046] The pattern area PR, viewed from above in the xy-view, is the region contained within the surface OBa of the object under inspection OB. The pattern area PR can be rectangular or circular. When the object under inspection OB is a master for nanoimprinting, the pattern area PR can also be a raised area on the surface Oba in a pedestal-like shape.

[0047] Figure 2 (b) is a top view showing the composition within the pattern area PR, and is Figure 2 (a) shows Figure 2 (a) Enlarged top view.

[0048] The pattern area PR comprises multiple inspection stripe areas SR-1 to SR-k (k being any integer greater than 2). These multiple inspection stripe areas SR-1 to SR-k are obtained by dividing the pattern area PR, for example, into stripes along the y-direction width of the illumination area RR. The illumination area RR represents the area that can be illuminated once by multiple beams (i.e., multiple beams MB-1 to MB-n). Each inspection stripe area SR extends along the x-direction. If the pattern area PR is rectangular when viewed from above in xy, the x-direction length of each inspection stripe area SR may also be equal.

[0049] The illumination area RR is defined as (the x-direction dimension obtained by multiplying the beam spacing in the x-direction of the multi-beam array on the OB surface of the object being inspected by the number of beams in the x-direction) × (the y-direction dimension obtained by multiplying the beam spacing in the y-direction of the multi-beam array on the OB surface of the object being inspected by the number of beams in the y-direction). Figure 2 In the example, it indicates that the width (y-direction dimension) of the inspected stripe area is the same as the y-direction dimension of the irradiated area. However, it is not limited to this.

[0050] Additionally, the width (y-direction dimension) of the stripe area can be greater than the y-direction dimension of the irradiated area. For example, it is preferable to set the width (y-direction dimension) of the stripe area to be a natural multiple of the y-direction dimension of the irradiated area.

[0051] In this embodiment, the inspection device 1 scans the irradiation area RR along the x-direction in each inspection stripe area SR (scanning action) to obtain an image of each irradiation area RR.

[0052] Irradiation area RR as Figure 2 (c) shows multiple inspection areas DR(1,1) to DR(5,5). Each inspection area DR is a region obtained by dividing the irradiation area RR into multiple parts, also known as a sub-irradiation area. Figure 2 (c) represents multiple examination areas DR(1,1) to DR(5,5) within the irradiation area RR. The multiple examination areas DR(1,1) to DR(5,5) can be arranged along the xy direction within the irradiation area RR. Figure 2 (c) Example of a multi-beam configuration containing 25 beams MB-1 to MB-25, arranged in 5 rows and 5 columns.

[0053] like Figure 2 As shown in (c), each beam MB constituting a multi-beam array is responsible for a different inspection area DR, scanning the same location within the corresponding inspection area DR. The circle represents one beam BM in the multi-beam array.

[0054] In each inspection area DR, the beam BM performs a raster scan. Within the inspection area DR, the beam BM scans from the -x and -y sides towards the +y direction. When it reaches the +y end of the inspection area DR, it deflects towards the -y end of the inspection area DR while simultaneously shifting towards the +x direction. Then, the beam BM scans towards the +y direction. The inspection device 1 repeats this operation, sequentially illuminating one inspection area DR using a single beam BM.

[0055] Figure 1 Before irradiating the object OB with the multiple beams MB-1 to MB-n used for inspection, the inspection device 1 shown pre-irradiates the object OB. For example, the inspection device 1 acquires the design data of the irradiation area RR. The design data of the irradiation area RR can also be... Figure 3 (a) shows the design data.

[0056] Figure 3 (a) Example of design data for the irradiation area RR. The design data includes a pattern formed on the object to be inspected OB. When the object to be inspected OB is a master for nanoimprinting, the pattern is formed as an embossed pattern in the pattern area PR. When the object to be inspected OB is a device substrate, the pattern is formed as a wiring pattern or a pattern of trenches or holes in the pattern area PR.

[0057] Figure 1The inspection device 1 shown calculates the pattern information of multiple inspection areas DR(1,1) to DR(5,5) based on the design data of the irradiation area RR. Based on the calculated pattern information of the multiple inspection areas DR(1,1) to DR(5,5), the inspection device 1 calculates the preliminary irradiation dose corresponding to each of the multiple inspection areas DR(1,1) to DR(5,5). For example... Figure 3 As shown in (b), the inspection device 1 can also calculate the preliminary irradiation dose (pre-irradiation dose) to make the charge equal among the multiple inspection areas DR(1,1) to DR(5,5).

[0058] Figure 3 (b) is a diagram that overlays multiple inspection areas DR(1,1) to DR(5,5) with their design data. Figure 3 In (b), the pre-exposure dose of DR in each examination area is represented by the size and intensity of the circle's color. The larger the circle, the greater the pre-exposure dose; the smaller the circle, the less the pre-exposure dose. The darker the circle's color, the greater the pre-exposure dose; the lighter the circle's color, the less the pre-exposure dose.

[0059] For example, when the object being inspected, OB, is a master plate used for nanoimprinting, the glass, quartz, or other substrates used for the master plate accumulate static electricity due to beam irradiation during inspection, thereby altering the brightness or contrast of the inspected image. Moreover, the charging status varies depending on the material of the object being inspected, the pattern size, the pattern coverage, the spacing between patterns, and other factors.

[0060] Therefore, the inspection device 1 will Figure 3 (a) The design data for the irradiation area RR shown is as follows: Figure 3 (b) shows the design data divided into multiple inspection areas DR(1,1) to DR(5,5). The inspection device 1 calculates pattern information based on the design data of each divided inspection area DR, determines the preliminary irradiation amount (pre-irradiation amount) based on the pattern information, and stores the preliminary irradiation amount in the pattern information storage device 4. The pattern information may also include at least one of pattern size, pattern coverage, and inter-pattern distance.

[0061] For example, when inspecting an object OB that is a master plate for nanoimprinting, the concave and convex patterns in the pattern area PR exhibit the following tendencies: smaller patterns are less likely to become charged, while larger patterns are more likely to become charged. The pattern size can be the average width of the concave pattern in the x and y directions, or the average width of the convex pattern in the x and y directions. The pattern size can be the minimum width of the concave pattern in the x and y directions, or the minimum width of the convex pattern in the x and y directions. The pattern size can be the maximum width of the concave pattern in the x and y directions, or the maximum width of the convex pattern in the x and y directions.

[0062] The inspection device 1 can also determine the size of the pattern in each segmented inspection area DR and determine the pre-irradiation amount based on the pattern size. When determining the pre-irradiation amount in three stages, if the pattern size of the inspection area DR is smaller than Sth1, the inspection device 1 can also determine the pre-irradiation amount to be "large". If the pattern size of the inspection area DR is greater than Sth1 and less than Sth2 (> Sth1), the inspection device 1 can also determine the pre-irradiation amount to be "medium". If the pattern size of the inspection area DR is greater than Sth2, the inspection device 1 can also determine the pre-irradiation amount to be "small".

[0063] Alternatively, when the object being inspected, OB, is a master plate for nanoimprinting, the concave and convex patterns in the pattern area, PR, tend to exhibit the following characteristics: patterns with smaller coverage are less likely to become charged, while patterns with larger coverage are more likely to become charged. Pattern coverage can be the ratio of the area of ​​the concave pattern to the area of ​​the inspection area, convex pattern to the area of ​​the inspection area, or the ratio of the area of ​​the boundary between the concave and convex patterns to the area of ​​the inspection area, PR.

[0064] The inspection device 1 can also calculate the coverage of the pattern in each segmented inspection area DR and determine the pre-irradiation amount based on the pattern coverage. When determining the pre-irradiation amount in three stages, if the pattern coverage of the inspection area DR is less than Cth1, the inspection device 1 determines the pre-irradiation amount to be "large". If the pattern coverage of the inspection area DR is greater than Cth1 but less than Cth2 (>Cth1), the inspection device 1 determines the pre-irradiation amount to be "medium". If the pattern coverage of the inspection area DR is greater than Cth2, the inspection device 1 determines the pre-irradiation amount to be "small".

[0065] Alternatively, when the object OB being inspected is a master plate for nanoimprinting, the concave and convex patterns in the pattern area PR exhibit the following tendency: patterns with shorter inter-pattern distances are less likely to become charged, while patterns with longer inter-pattern distances are more likely to become charged. The inter-pattern distance can be the average xy-direction distance between concave patterns, the average xy-direction distance between convex patterns, or the average xy-direction distance between the boundary portions of concave and convex patterns.

[0066] The inspection device 1 can also calculate the inter-pattern distance for each segmented inspection area DR and determine the pre-irradiation amount based on the inter-pattern distance. When determining the pre-irradiation amount in three stages, if the inter-pattern distance of the inspection area DR is less than Dth1, the inspection device 1 determines the pre-irradiation amount to be "large". If the inter-pattern distance of the inspection area DR is greater than Dth1 but less than Dth2 (>Dth1), the inspection device 1 determines the pre-irradiation amount to be "medium". If the inter-pattern distance of the inspection area DR is greater than Dth2, the inspection device 1 determines the pre-irradiation amount to be "small".

[0067] Furthermore, the inspection device 1 can also adjust the irradiation dose of the DR in each inspection area based on the material information of the object OB being inspected. The material of the object OB being inspected is set to be K times that of the reference material, where the emission rate of secondary electrons relative to primary electrons is K times that of the reference material. In this case, the inspection device 1 can also adjust the irradiation dose of the DR in each inspection area using the following mathematical formulas 1 to 3: (Pre-irradiation dose of the DR in the inspection area with "high" irradiation dose) = ("high" irradiation dose) × K... Mathematical Formula 1 (Pre-irradiation dose of the DR in the inspection area with "medium" irradiation dose) = ("medium" irradiation dose) × K... Mathematical Formula 2 (Pre-irradiation dose of the DR in the inspection area with "low" irradiation dose) = ("low" irradiation dose) × K... Mathematical Formula 3

[0068] For example, the material information may also include information related to the K value. The inspection device 1 may also read the material information from the material information storage device 5 and adjust the irradiation dose of each inspection area using mathematical formulas 1 to 3 based on the read material information.

[0069] After determining the pre-irradiation dose of DR for each inspection area, the inspection device 1 manufactures... Figure 3 (b) The pre-irradiation map is shown and stored in the pre-irradiation map storage device 6. During preparatory irradiation, the inspection device 1 irradiates multiple inspection areas DR with multiple beams MB-1 to MB-n at a pre-irradiation amount corresponding to the pre-irradiation map.

[0070] in addition, Figure 3 (b) represents the pre-exposure dose in three stages: large, medium, and small, but it is not limited to this. Pre-exposure maps can also be created using pre-exposure doses in more stages, or even using pre-exposure doses in two stages.

[0071] Pre-irradiation dose can be as follows Figure 4 Adjustments are shown. Figure 4 This is a diagram showing the adjustment action of the pre-irradiation dose. Figure 1 In the inspection device 1 shown, the blanking aperture 14 can arbitrarily change the scanning trajectory and scanning speed of each beam MB in the inspection area DR through the blanking aperture control unit 34.

[0072] like Figure 4 (a)~ Figure 4 As shown in (c), the irradiation dose can also be adjusted by changing the scanning density in the raster scan. The higher the scanning density, the greater the irradiation dose. Figure 4 (a) Figure 4 (b) Figure 4 (c) Examples of scanning in the y direction using 9, 5, and 3 orbits arranged along the x direction. Figure 4 (a) Figure 4 (b) Figure 4 In (c), the scanning densities are large, medium, and small, respectively, which are equivalent to... Figure 3 (b) High exposure, medium exposure, low exposure.

[0073] like Figure 4 (d)~ Figure 4 As shown in (f), the irradiation dose can also be adjusted by changing the scanning speed in the raster scan. The higher the scanning speed, the greater the irradiation dose. Figure 4 (d) Figure 4 (e) Figure 4 (f) The arrow lengths illustrate the scanning in the y direction at high speed, medium speed, and low speed, respectively. Figure 4 (d) Figure 4 (e) Figure 4 The scan speeds in (f) are large, medium, and small, respectively, which are equivalent to... Figure 3 (b) High, medium, and low exposure levels. Alternatively, [the following can be considered]: Figure 4 (a)~ Figure 4 (c) shows the adjustment and Figure 4 (d)~ Figure 4 The adjustments shown in (f) are combined to adjust the irradiation dose by changing the scanning density and speed in the raster scan.

[0074] Next, the steps for preparatory irradiation (pre-irradiation) of the pattern area PR, irradiation for inspection, and image acquisition will be described. The implementation steps can be broadly categorized into two steps. The first step is... Figure 5 The implementation steps shown are for scanning the stripe area SR as a unit. The second step is to... Figure 6 The implementation steps for scanning the upper and lower halves of the striped area SR shown are as follows: the area is divided into two parts along the y-direction. Figure 5 and Figure 6 These are diagrams illustrating the operation of the inspection device 1.

[0075] Figure 5In the implementation steps, the inspection device 1 performs pre-irradiation on a single inspection stripe area SR by scanning the irradiation area RR along a first direction, and performs inspection irradiation and image acquisition on the same inspection stripe area SR by scanning the irradiation area RR along a second direction. The first direction is along the x-direction. The second direction is along the x-direction and is opposite to the first direction.

[0076] For example Figure 5 (a) As shown by the dashed arrow, the inspection device 1 performs pre-irradiation while scanning the irradiation area RR from the -x side end towards the +x direction within the inspection stripe area SR-1. Specifically, the inspection device 1 positions the irradiation area RR at the -x side end within the inspection stripe area SR-1 and pre-irradiates each inspection area DR within the irradiation area RR with various pre-irradiation amounts. After completing the pre-irradiation, the inspection device 1 moves the irradiation area RR to an adjacent position on the +x side within the inspection stripe area SR-1 and pre-irradiates each inspection area DR within the irradiation area RR with various pre-irradiation amounts. As shown by the dashed arrow, the inspection device 1 alternately repeats the pre-irradiation of the irradiation area RR and the movement of the irradiation area RR to the adjacent position until it reaches the +x side end position.

[0077] After pre-irradiation is completed at the +x side end of the SR-1 stripe area, the inspection device 1 is as follows: Figure 5 As shown by the solid arrow in (b), the inspection apparatus 1 scans the irradiation area RR in the -x direction while simultaneously performing inspection irradiation and image acquisition. Specifically, the inspection apparatus 1 maintains the irradiation area RR at the +x side end position and performs inspection irradiation and image acquisition on each inspection area DR within the irradiation area RR, for example, with equal irradiation amounts. When the inspection apparatus 1 completes the inspection irradiation at the +x side end position, it moves the irradiation area RR to a position adjacent to the inspection stripe area SR-1 on the -x side, and performs inspection irradiation and image acquisition on each inspection area DR within the irradiation area RR, for example, with equal irradiation amounts. As shown by the solid arrow, the inspection apparatus 1 alternately and repeatedly performs inspection irradiation and image acquisition on the irradiation area RR and moves the irradiation area RR to the adjacent position.

[0078] After pre-irradiation is completed at the -x side end of the inspection stripe area SR-1, the inspection device 1 moves the irradiation area RR in the +y direction, so that the irradiation area RR is located at the -x side end of the inspection stripe area SR-2.

[0079] Inspection device 1 as Figure 5 As shown by the dashed arrow in (c), in the stripe area SR-2, the irradiation area RR is scanned from the -x side position towards the +x direction while pre-irradiation is performed.

[0080] After pre-irradiation is completed at the +x side end of the SR-2 stripe area, the inspection device 1 is as follows: Figure 5 As shown by the solid arrow in (d), the irradiation area RR is scanned in the -x direction within the inspection stripe area SR-2 while the inspection irradiation and image acquisition are performed.

[0081] Figure 6 In the implementation steps, the inspection stripe area SR is divided into upper and lower halves (y-direction half), becoming the upper half (+y side) half-stripe area SRU and the lower half (-y side) half-stripe area SRL. The upper half of the irradiation area RR is designated as RRU, and the lower half as RRL. The inspection device 1 performs pre-irradiation by scanning the half-stripe area RRU along the first direction within the half-stripe area SRU, and performs inspection irradiation and image acquisition by scanning the half-stripe area RRL along the first direction within the half-stripe area SRL. The inspection device 1 moves the y-direction width of the half-stripe area by the amount in the +y direction. The inspection device 1 performs pre-irradiation by scanning the half-stripe area RRU along the second direction within the half-stripe area SRL, and performs inspection irradiation and image acquisition by scanning the half-stripe area RRL along the second direction within the half-stripe area SRU.

[0082] For example, inspection device 1 Figure 6 As shown by the dashed arrow in (a), pre-irradiation is performed on the half-region RRU within the half-striped region SRU-1, scanning from the -x side to the +x direction. Simultaneously, the inspection device 1... Figure 6 As shown by the dashed and solid arrows in (a), the half-striped region SRL is scanned from the -x side to the +x direction within the half-striped region SRL-1, while pre-irradiation, irradiation for inspection, and image acquisition are performed.

[0083] After pre-irradiation is completed at the +x side end position of half-striped region SRU-1 and image acquisition is completed at the +x side end position of half-striped region SRL-1, inspection device 1 moves half-region RRU in the +y direction to the +x side end of half-striped region SRL-2, and moves half-region RRL in the +y direction to the +x side end of half-striped region SRU-1.

[0084] Inspection device 1 as Figure 6 As shown by the dashed arrow in (b), pre-irradiation is performed on the half-region RRU within the half-striped region SRL-2, scanning from the +x side end towards the -x direction. Simultaneously, the inspection device 1... Figure 6 As shown by the solid arrow in (b), the half-striped region SRU-1 is scanned from the +x side to the -x direction to perform irradiation and image acquisition for inspection.

[0085] After pre-irradiation is completed at the -x side end position of the half-striped region SRL-2 and image acquisition is completed at the -x side end position of the half-striped region SRU-1, the inspection device 1 moves the half-region RRU in the +y direction to the -x side end of the half-striped region SRU-2, and moves the half-region RRL in the +y direction to the -x side end of the half-striped region SRL-2.

[0086] Inspection device 1 as Figure 6 As shown by the dashed arrow in (c), pre-irradiation is performed on the half-region RRU within the half-striped region SRU-2, scanning from the -x side to the +x direction. Simultaneously, the inspection device 1... Figure 6 As shown by the solid arrow in (c), the half-striped region SRL is scanned from the -x side to the +x direction within the half-striped region SRL-2, while irradiation and image acquisition for inspection are performed.

[0087] After pre-irradiation is completed at the +x side end position of the half-striped region SRU-2 and image acquisition is completed at the +x side end position of the half-striped region SRL-2, the inspection device 1 moves the half-region RRU in the +y direction to the +x side end position of the half-striped region SRL-3, and moves the half-region RRL in the +y direction to the +x side end position of the half-striped region SRU-2.

[0088] Inspection device 1 as Figure 6 As shown by the dashed arrow in (d), pre-irradiation is performed on the half-region RRU within the half-striped region SRL-3, scanning from the +x side end towards the -x direction. Simultaneously, the inspection device 1... Figure 6 As shown by the solid arrow in (d), the half-striped region SRU-2 is scanned from the +x side to the -x direction to perform irradiation and image acquisition for inspection.

[0089] Next, use Figure 7 The operation procedure of inspection device 1 is explained. Figure 7 This is a flowchart illustrating the operation of the inspection device 1. Figure 7 An example illustrating the steps of a multibeam inspection method.

[0090] The inspection device 1 reads the design data of the pattern area PR from the pattern information storage device 4 into the control computer 3 (S1). The design data can also be two-dimensional design data (e.g., layout design data). The inspection device 1 reads the material information of the object OB to be inspected from the material information storage device 5 into the control computer 3 (S2). Based on the design data read in S1 and the material information read in S2, the inspection device 1 creates pre-illumination maps of multiple inspection areas DR (S3) and stores them in the pre-illumination map storage device 6.

[0091] For example, inspection device 1 divides the design data of pattern area PR into design data of multiple inspection stripe areas SR, and further divides the design data of each inspection stripe area SR into design data of illumination areas RR at multiple locations. Inspection device 1 divides the design data of illumination areas RR at each location into design data of multiple inspection areas DR. Inspection device 1 calculates the pattern information of multiple inspection areas DR based on the design data of multiple inspection areas DR. The pattern information may also include at least one of pattern size, pattern coverage, and pattern spacing. Inspection device 1 calculates the illumination amount of multiple beams MB corresponding to multiple inspection areas based on the pattern information of multiple inspection areas DR. Inspection device 1 may also adjust the illumination amount of each inspection area DR according to the material information of the object OB being inspected. Inspection device 1 may also create a pre-illumination map of multiple inspection areas DR based on the illumination amount of each inspection area DR.

[0092] When the timing for pre-illumination is required, the inspection device 1 reads a pre-illumination map from the pre-illumination map storage device 6. Based on the pre-illumination map, the inspection device 1 determines the steps for performing pre-illumination in the pattern area PR, as well as illumination and image acquisition for inspection (S4). For example, the inspection device 1 may determine the steps for performing pre-illumination in the pattern area PR, as well as illumination and image acquisition for inspection, as follows: Figure 5 The implementation steps shown can also be determined as follows: Figure 6 The implementation steps are shown below. Following the implementation steps determined in S4, the inspection device 1 performs pre-illumination of multiple inspection areas DR, as well as illumination and image acquisition for inspection (S5). At this time, when focusing on the illumination areas RR at the same location, the inspection device 1 pre-illuminates multiple inspection areas DR with multiple beams MB at the calculated illumination amount. While performing this pre-illumination, the inspection device 1 illuminates the multiple inspection areas DR with multiple beams MB. The inspection device 1 generates images of the multiple inspection areas DR illuminated by the multiple beams MB.

[0093] Inspection device 1 performs inspection (S6). For example, inspection device 1 may also synthesize the images of each inspection area DR acquired in S5 for the entire pattern DR to generate a whole image, and use the whole image for inspection. Alternatively, inspection device 1 may also use the images of each inspection area DR acquired in S5 for the inspection stripe area SR (refer to...). Figure 5 The stripe image is generated by combining the images of the stripe regions (DR) acquired in S5, and then used to inspect each stripe region (SR). Alternatively, the inspection device 1 can also use the images of each inspection region (DR) acquired in S5 to target the irradiation region (RR) at each location (see reference). Figure 5 , Figure 6 The illumination area image is generated by synthesis, and the illumination area image is used to check the illumination area RR at each location.

[0094] As described above, in this embodiment, the inspection device 1 calculates a preliminary irradiation amount corresponding to each of the multiple inspection areas based on pattern information of those areas. The inspection device 1 then preliminarily irradiates the multiple inspection areas of the object to be inspected, OB, with the calculated irradiation amount. Afterward, with the preliminary irradiation complete, the inspection device 1 irradiates the multiple inspection areas with multiple inspection beams MB-1 to MB-n. This allows for the irradiation of primary electrons by the inspection beams, ensuring that the emission rate of secondary electrons relative to primary electrons is equal in the multiple inspection areas using the preliminary beam irradiation. As a result, the emission rate of secondary electrons more accurately reflects the surface condition of the object to be inspected, thus suppressing variations in brightness or contrast in each inspection image and improving the inspection accuracy of the inspection device 1.

[0095] In addition, such as Figure 8 As shown, the inspection device 1a may also obtain a pre-irradiation map from an external pre-irradiation map generation system 100 instead of generating a pre-irradiation map. Figure 8 This is a diagram showing the configuration of the inspection device 1a in a variation of the implementation method.

[0096] The pattern information storage device 4, material information storage device 5, and pre-irradiation image storage device 6 are omitted from the inspection device 1a (see reference). Figure 1 Furthermore, it has an interface (I / F) section 9a. The pre-irradiation image generation system 100 includes a control device 103, a pattern information storage device 104, a material information storage device 105, a pre-irradiation image storage device 106, and an interface (I / F) section 109a. The pre-irradiation image generation system 100 can also be implemented as a computer, for example.

[0097] For example, when the I / F unit 9a and I / F unit 109a are connected by a communication line, the inspection device 1a sends a pre-illumination pattern creation request from the I / F unit 9a to the pre-illumination pattern generation system 100 via the communication line. In the pre-illumination pattern generation system 100, when a pre-illumination pattern creation request is received through the I / F unit 9a, the control unit 103 reads design data from the pattern information storage device 4 and reads the material information of the inspection object OB from the material information storage device 5 into the control computer 3. Based on the read design data and the read material information, the control unit 103 creates pre-illumination patterns of multiple inspection areas DR and stores them in the pre-illumination pattern storage device 106.

[0098] When the timing for pre-irradiation is deemed appropriate, the inspection device 1a sends a pre-irradiation map acquisition request from the I / F unit 9a to the pre-irradiation map generation system 100 via a communication line. In the pre-irradiation map generation system 100, when a pre-irradiation map generation request is received via the I / F unit 9a, the control unit 103 reads the pre-irradiation map from the pre-irradiation map storage device 106 and sends the pre-irradiation map from the I / F unit 109a to the inspection device 1a via the communication line. Upon receiving the pre-irradiation map from the I / F unit 9a, the inspection device 1a performs... Figure 7 The processing of S5 and S6.

[0099] Alternatively, even if the I / F units 9a and 109a are not connected by a communication line, the pre-illumination pattern generation system 100 can still input a pre-illumination pattern creation request via the I / F unit 109a. When a pre-illumination pattern creation request is input, the control unit 103 reads design data from the pattern information storage device 4 and reads the material information of the inspection object OB from the material information storage device 5 into the control computer 3. Based on the read design data and the read material information, the control unit 103 creates pre-illumination patterns for multiple inspection areas DR and stores them in the pre-illumination pattern storage device 106.

[0100] When the inspection device 1a detects a pre-irradiation sequence, it displays a message indicating that pre-irradiation should be performed on the display device 8 to notify the user. Based on this notification, the pre-irradiation image generation system 100 can also connect an external storage medium (not shown) to the I / F section 109a and input a pre-irradiation image acquisition request via the I / F section 109a. When a pre-irradiation image acquisition request is input, the control unit 103 reads the pre-irradiation image from the pre-irradiation image storage device 106 and stores it in the external storage medium via the I / F section 109a. Corresponding to this storage, the inspection device 1a connects an external storage medium to the I / F section 9a and inputs a pre-irradiation image from the external storage medium via the I / F section 9a. When a pre-irradiation image is input via the I / F section 9a, the inspection device 1a performs... Figure 7 The processing of S5 and S6.

[0101] Thus, in the inspection device 1a, a pre-irradiation image is not generated; instead, it is obtained from an external pre-irradiation image generation system 100. Correspondingly, the pattern information storage device 4, the material information storage device 5, and the pre-irradiation image storage device 6 are omitted. This simplifies the configuration of the inspection device 1a and reduces its cost.

[0102] Furthermore, in the above embodiment, the original template used for nanoimprinting is used as an example to illustrate the object OB to be inspected. However, this embodiment can also be applied to the inspection of EUV (extreme ultraviolet) masks and actual device substrates. In this case, the positively charged state where the inspection image brightens may not be optimal; the point where the inspection image darkens and becomes negatively charged is the boundary between positive and negative charges. That is, pre-irradiation can also be performed in a state where the charge weakens.

[0103] Several embodiments of the present invention have been described, but these embodiments are provided by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, and are included in the invention as described in the claims and its equivalents.

Claims

1. An inspection apparatus capable of irradiating a plurality of first beams to a plurality of inspection regions with one irradiation, comprising: a control section that calculates, based on pattern information of the plurality of inspection regions in an inspection object including the plurality of inspection regions, an irradiation amount of the plurality of first beams corresponding to the plurality of inspection regions, respectively; an irradiation section that preliminarily irradiates the plurality of first beams to the plurality of inspection regions with the calculated irradiation amount, respectively, and irradiates a plurality of second beams to the plurality of inspection regions in a state where the preliminary irradiation is performed; and a generation section that generates images of the plurality of inspection regions irradiated with the plurality of second beams.

2. The inspection apparatus according to claim 1, wherein the control section detects a defect of the inspection object based on images of the plurality of inspection regions.

3. The inspection apparatus according to claim 1, wherein the pattern information includes at least one of a pattern size, a pattern coverage, and a distance between patterns.

4. The inspection apparatus according to claim 1, wherein the irradiation section has: a generation section that generates a charged particle beam; a division section that divides the generated charged particle beam into the plurality of first beams or the plurality of second beams; and an adjustment section that adjusts an irradiation amount of the divided plurality of first beams or the plurality of second beams to the plurality of inspection regions, respectively; and the control section controls driving of the generation section, the division section, and the adjustment section in a manner that preliminarily irradiates the plurality of first beams to the plurality of inspection regions with the calculated irradiation amount, respectively, and irradiates a plurality of second beams to the plurality of inspection regions in a state where the preliminary irradiation is performed. calculating, based on pattern information of the plurality of inspection regions, an irradiation amount of the plurality of first beams corresponding to the plurality of inspection regions, respectively; 5. An inspection method capable of irradiating a plurality of first beams to a plurality of inspection regions with one irradiation, comprising the step of acquiring pattern information of the plurality of inspection regions with respect to an inspection object including the plurality of inspection regions. preliminarily irradiating the plurality of first beams to the plurality of inspection regions with the calculated irradiation amount, respectively; irradiating a plurality of second beams to the plurality of inspection regions in a state where the preliminary irradiation is performed; and generating images of the plurality of inspection regions irradiated with the plurality of second beams.

6. The inspection method according to claim 5, wherein a defect of the inspection object is detected based on images of the plurality of inspection regions.

Images