Mask inspection apparatus and mask inspection method

Abstract

PURPOSE: To provide an inspection device with which it is possible to suppress background reflections of a ghost image.CONSTITUTION: An inspection device 100 in one embodiment of the present invention is characterized by having: a lens array 304 for dividing inspection light into multiple rays of light upon receiving radiation of the inspection light; a lens array stage 320 for supporting the lens array and capable of moving in a plane orthogonal to the optical axis of the inspection light; an objective lens 104 for irradiating a mask substrate on which a diagram pattern is formed, with at least some of the multiple rays of light; an imaging sensor 105 for capturing an optical image of the mask substrate that is obtained by irradiating the mask substrate with light; a luminous quantity sensor 324 for measuring the luminous quantity of the inspection light; and a stage control circuit 140 for controlling a stage so that the position of the lens array is changed when the integral amount of measured luminous quantities increases to a threshold or greater.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a mask inspection apparatus and a mask inspection method, for example, to an inspection apparatus that inspects a pattern on a mask substrate for defects. [Background technology]

[0002] In recent years, with the increasing integration and capacity of large-scale integrated circuits (LSI), the circuit line width required for semiconductor elements has become increasingly narrow. These semiconductor elements are manufactured by forming circuits by exposing and transferring the pattern onto a wafer using a reduced projection exposure device called a stepper, using an original pattern (also called a mask or reticle, hereinafter collectively referred to as a mask) on which the circuit pattern is formed.

[0003] Improving yield is essential for the manufacture of LSIs, which are very costly to manufacture. One of the major factors that reduces yield is pattern defects, such as shape and / or dimensional defects, in the mask patterns used when exposing and transferring ultra-fine patterns onto semiconductor wafers using photolithography technology. In recent years, as the dimensions of LSI patterns formed on semiconductor wafers have become increasingly miniaturized, the dimensions that must be detected as pattern defects have also become extremely small. This has led to a need for higher-precision pattern inspection systems that inspect the transfer masks used in LSI manufacturing for defects.

[0004] Inspection techniques include, for example, "die-to-die inspection," which compares optical image data captured of the same pattern at different locations on the same mask, and "die-to-database inspection," which converts pattern-design CAD data into a device input format for input by a drawing device when drawing the pattern on a mask, inputs the converted drawing data (design data) into an inspection device, generates a reference image based on this, and compares it with an optical image that serves as measurement data captured from the pattern.

[0005] When imaging a pattern on a mask, Koehler illumination, for example, is used to generate inspection light that can uniformly illuminate the surface. In Koehler illumination, a lens array is used to split laser light at equal intervals. When imaging a pattern on a mask using such Koehler illumination, reflections (ghost images) may occur in the resulting image. If each light split by the lens array is condensed and an optical element is placed at a position where the irradiation energy is concentrated, the optical element at each condensed position will be deteriorated due to prolonged irradiation of each light with concentrated irradiation energy, resulting in the formation of a phase grating. When a phase grating is formed, part of the inspection light is diffracted and captured as a ghost image. Therefore, it is desirable to suppress the reflection of ghost images.

[0006] Conventionally, measures have been taken to suppress deterioration by slightly moving the lens array in a direction perpendicular to the optical axis every time a predetermined time has elapsed (see, for example, Patent Document 1). However, ghosting still occurs in some cases. For this reason, further improvements are needed. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-267903 Summary of the Invention [Problem to be solved by the invention]

[0008] Therefore, an embodiment of the present invention provides an inspection device and method that can suppress the reflection of ghost images. [Means for solving the problem]

[0009] A mask inspection apparatus according to one aspect of the present invention includes: a lens array that receives the inspection light and splits the inspection light into a plurality of beams; a stage that supports the lens array and is movable in a plane perpendicular to the optical axis of the inspection light; a lens for irradiating a mask substrate on which a graphic pattern is formed with at least some of the plurality of light beams; an imaging sensor that captures an optical image of the mask substrate by illuminating the mask substrate; a light intensity sensor for measuring the intensity of the inspection light; a control unit that controls the stage to change the position of the lens array when the measured integrated light amount becomes equal to or greater than a threshold value; The present invention is characterized by the following.

[0010] The stage also moves in a direction parallel to the surface within the plane. Preferably, the control unit controls the stage so that the position of the lens array is shifted by translation when the measured integrated light amount becomes equal to or greater than a threshold value.

[0011] and / or the stage rotates in a plane; Preferably, the control unit controls the stage so that the position of the lens array is shifted by rotation when the measured integrated light amount becomes equal to or greater than a threshold value.

[0012] Another aspect of the mask inspection apparatus of the present invention is First and second lens arrays, each having a different lens arrangement pitch, receive the inspection light and split the inspection light into a plurality of beams; a stage that supports the first and second lens arrays and is movable in a plane perpendicular to the optical axis of the inspection light; a lens that irradiates a mask substrate on which a graphic pattern is formed with at least some of the light beams split by one of the first and second lens arrays; an imaging sensor that captures an optical image of the mask substrate by illuminating the mask substrate; a light intensity sensor for measuring the intensity of the inspection light; a control unit that controls the stage to switch the lens array irradiated with the inspection light from one of the first and second lens arrays to the other when the measured integrated light amount becomes equal to or greater than a threshold value; The present invention is characterized by the following.

[0013] Another aspect of the mask inspection apparatus of the present invention is a lens array that receives the inspection light and splits the inspection light into a plurality of beams; a stage that supports the lens array and is movable in a plane perpendicular to the optical axis of the inspection light; a lens for irradiating a mask substrate on which a graphic pattern is formed with at least some of the plurality of light beams; an imaging sensor that captures an optical image of the mask substrate by illuminating the mask substrate; a control unit that controls the stage to shift the position of the lens array under predetermined conditions; a recording processing unit that uses the captured optical image to record a gradation value at a predetermined position on the image of the figure pattern for each position of the lens array; an order determination unit that determines the order in which the lens array is to be moved next, giving priority to the lens array positions corresponding to smaller gradation values ​​than the lens array positions corresponding to larger gradation values ​​among the gradation values ​​recorded for each position of the lens array in the kth iteration; The present invention is characterized by the following.

[0014] The image forming apparatus further includes a sorting processing unit that sorts the recorded gradation values ​​for each position of the lens array in the kth iteration in ascending order, The order determination unit preferably determines the order of movement of each position of the lens array in the (k+1)th turn in ascending order of tone value.

[0015] Alternatively, an extracting unit may be further provided that extracts gradation values ​​equal to or less than a threshold value from among the gradation values ​​recorded for each position of the lens array in the kth iteration, It is preferable that the order determination unit determines the movement order so that before moving to each position of the lens array in the k+1th cycle, the lens array is moved to a position corresponding to at least one extracted gradation value, and then the lens array is moved to each position of the k+1th cycle.

[0016] A mask inspection method according to one aspect of the present invention includes: a step of irradiating an inspection light onto a lens array and splitting the inspection light into a plurality of light beams by the lens array; irradiating a mask substrate having a graphic pattern formed thereon with at least some of the plurality of lights using a lens; capturing an optical image of the mask substrate using an imaging sensor, the optical image being obtained by illuminating the mask substrate; comparing the captured optical image of the mask substrate with a predetermined image and outputting the result; measuring the amount of inspection light using a light amount sensor; changing the position of the lens array in a plane perpendicular to the optical axis of the inspection light when the measured integrated light amount is equal to or greater than a threshold value; The present invention is characterized by the following.

[0017] Another aspect of the present invention is a mask inspection method, A step of irradiating a first lens array with inspection light and dividing the inspection light into a plurality of light beams by the lens array; irradiating a mask substrate having a graphic pattern formed thereon with at least some of the plurality of lights using a lens; capturing an optical image of the mask substrate using an imaging sensor, the optical image being obtained by illuminating the mask substrate; comparing the captured optical image of the mask substrate with a predetermined image and outputting the result; measuring the amount of inspection light using a light amount sensor; a step of switching the lens array irradiated with the inspection light from the first lens array to a second lens array having a lens arrangement pitch different from that of the first lens array when the measured integrated light amount is equal to or greater than a threshold value; The present invention is characterized by the following.

[0018] Another aspect of the present invention is a mask inspection method, shifting the position of the lens array under predetermined conditions; a step of irradiating the lens array with inspection light at each position of the lens array and dividing the inspection light into a plurality of light beams by the lens array; irradiating, at each position of the lens array, a corresponding mask substrate among a plurality of mask substrates on which graphic patterns are formed, with at least some of the plurality of lights using a lens; capturing, for each position of the lens array, an optical image of the corresponding mask substrate obtained by illuminating the corresponding mask substrate using an imaging sensor; comparing the captured optical image of the corresponding mask substrate with a predetermined image for each position of the lens array and outputting the result; a step of recording a gradation value at a predetermined position of the image of the graphic pattern using the captured optical image for each position of the lens array; determining the order of movement of each position of the lens array to be moved next by prioritizing the lens array position corresponding to a smaller gradation value among the gradation values ​​recorded for each position of the lens array in the kth iteration over the lens array position corresponding to a larger gradation value; A mask inspection method comprising: [Effects of the Invention]

[0019] According to the embodiment of the present invention, ghost images can be suppressed, and as a result, detection of false defects can be suppressed. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a configuration diagram showing a configuration of a pattern inspection device according to a first embodiment. [Figure 2] FIG. 2 is a conceptual diagram for explaining an inspection area in the first embodiment. [Figure 3] FIG. 10 is a diagram for explaining the influence of the lens array in the first comparative example of the first embodiment. [Figure 4] FIG. 10 is a diagram for explaining the occurrence of a ghost image in Comparative Example 1 of Embodiment 1. [Figure 5] FIG. 10 is a diagram showing an example of a ghost image in Comparative Example 1 of the first embodiment. [Figure 6] FIG. 10 is a diagram showing another example of a ghost image in Comparative Example 1 of Embodiment 1. [Figure 7] 1 is a front view showing an example of the configuration of a lens array according to the first embodiment. [Figure 8] 1 is a side view showing an example of the configuration of a lens array according to the first embodiment. [Figure 9] FIG. 3 is a diagram showing an example of a shift position of the lens array according to the first embodiment. [Figure 10] FIG. 10 is a diagram showing an example of a plurality of focal points on an objective lens in a first comparative example of the first embodiment. [Figure 11] FIG. 10 is a diagram showing an example of a plurality of focal points on the objective lens after one shift cycle has been completed in the first embodiment. [Figure 12] FIG. 10 is a diagram showing an example of a shift order of the lens array in a second comparative example of the first embodiment. [Figure 13] 10A and 10B are front views showing an example of positions of the lens array before and after shifting in a modification of the first embodiment. [Figure 14] FIG. 10 is a diagram showing an example of a plurality of light-converging points before and after a shift in a modification of the first embodiment. [Figure 15] FIG. 3 is a diagram illustrating a filter process according to the first embodiment. [Figure 16] 3 is a diagram illustrating an example of an internal configuration of a comparison circuit according to the first embodiment. FIG. [Figure 17] FIG. 10 is a configuration diagram showing the configuration of a pattern inspection device according to a second embodiment. [Figure 18] 10 is a side view showing an example of a plurality of lens arrays according to the second embodiment. FIG. [Figure 19] FIG. 10 is a configuration diagram showing the configuration of a pattern inspection device according to a third embodiment. [Figure 20] FIG. 11 is a block diagram showing an example of the internal configuration of a lens array position control circuit according to the third embodiment. [Figure 21] FIG. 11 is a flowchart showing an example of main steps of an inspection method according to the third embodiment. [Figure 22] FIG. 11 is a top view showing an example of a mask substrate according to the third embodiment. [Figure 23]FIG. 11 is a diagram showing an example of a moving table in the third embodiment. [Figure 24] FIG. 11 is a diagram showing an example of a moving table after sorting processing in the third embodiment. [Figure 25] FIG. 11 is a diagram showing an example of the relationship between shift position and glare intensity in the third embodiment. [Figure 26] FIG. 11 is a diagram showing another example of the relationship between the shift position and the reflection intensity in the third embodiment. [Figure 27] FIG. 13 is a block diagram showing an example of the internal configuration of a lens array position control circuit according to the fourth embodiment. [Figure 28] FIG. 11 is a flowchart showing an example of some of the main steps of an inspection method according to the fourth embodiment. [Figure 29] FIG. 13 is a flowchart showing an example of the remaining main steps of the inspection method according to the fourth embodiment. [Figure 30] FIG. 13 is a diagram showing an example of an extraction table in the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0021] Embodiment 1 Fig. 1 is a configuration diagram showing the configuration of a pattern inspection device according to embodiment 1. In Fig. 1, an inspection device 100 that inspects pattern defects formed on a substrate 101 (an example of a substrate to be inspected) includes an optical image acquisition mechanism 150 and a control system circuit 160 (a control unit).

[0022] The optical image acquisition mechanism 150 includes a light source 103 that generates laser light, a Kohler illumination optical system 300, a lens array stage 320, a drive mechanism 322, a relay lens 31, a beam splitter 32, a reflective illumination optical system 270, an XYθ table 102, an objective lens 104, a beam splitter 176, an imaging optical system 178, an imaging sensor 105, a sensor circuit 106, a stripe pattern memory 123, and a light intensity sensor 324.

[0023] The reflective illumination optical system 270 is configured by one or more lenses and / or one or more mirrors. In the example of FIG.

[0024] A substrate 101, which has been transferred from an autoloader (not shown), is placed on the XYθ table 102. The substrate 101 includes, for example, a photomask for exposure that transfers a pattern onto a semiconductor substrate such as a wafer. This photomask has a plurality of graphic patterns formed thereon to be inspected. The substrate 101 is placed on the XYθ table 102 with the pattern-formed surface facing downward, for example.

[0025] It is preferable to use, for example, a TDI (time delay integration) sensor as the image sensor 105. A TDI sensor has a plurality of photosensor elements arranged two-dimensionally. When capturing an image, a predetermined image accumulation time (sometimes referred to as a scan time; the same applies hereinafter) is set for each photosensor element. In a TDI sensor, the outputs of a plurality of photosensor elements arranged in the scan direction are integrated and output. The plurality of photosensor elements arranged in the scan direction capture the same pixel at different times in accordance with the movement of the XYθ table 102.

[0026] The Koehler illumination optical system 300 includes, for example, a beam expander 302 , a lens array 304 , a collimator lens 308 , and an illumination slit 310 .

[0027] The lens array 304 is disposed on a lens array stage 320. The lens array stage 320 supports the lens array 304 and is disposed so as to be movable in a plane perpendicular to the optical axis of the inspection light. The lens array stage 320 is moved in the plane perpendicular to the optical axis by a driving mechanism 322.

[0028] The objective lens 104 may be made up of a single lens, or may be made up of a combination of multiple lenses.

[0029] In the control system circuit 160, a control computer 110 that controls the entire inspection device 100 is connected via a bus 120 to a magnetic disk device 109, a memory 111, a position circuit 107, a comparison circuit 108, a reference image creation circuit 112, a table control circuit 114, and a stage control circuit 140.

[0030] The stripe pattern memory 123 is connected to the comparison circuit 108. The reference image creation circuit 112 is also connected to the comparison circuit 108.

[0031] The output of the light amount sensor 324 is connected to the stage control circuit 140. The stage control circuit 140 also controls the drive mechanism 322.

[0032] The XYθ table 102 is driven by a driving mechanism 115. The driving mechanism 115 has, for example, an X-axis motor, a Y-axis motor, and a θ-axis motor in a coordinate system within a plane perpendicular to the optical axis of the inspection light incident on the substrate 101, and the XYθ table 102 is driven by the X-axis motor, the Y-axis motor, and the θ-axis motor. The XYθ table 102 is an example of a stage.

[0033] The driving mechanism 322 also has, for example, an X-axis motor, a Y-axis motor, and a θ-axis motor in a coordinate system in a plane perpendicular to the optical axis of the inspection light incident on the lens array 304, and the lens array stage 320 is driven by the X-axis motor, the Y-axis motor, and the θ-axis motor.

[0034] The X-axis motor, Y-axis motor, and θ-axis motor may be, for example, a linear motor. The XYθ table 102 can be moved in the horizontal direction and in the rotational direction by the motors of the X, Y, and θ axes.

[0035] Furthermore, the XYθ table 102 is adjusted to the focal position (optical axis direction: Z axis direction) between the pattern-formed surface of the substrate 101 and the imaging sensor 105 under the control of the control computer 110. The movement position of the substrate 101 placed on the XYθ table 102 is measured by a laser length measurement system (not shown) and supplied to a position circuit 107.

[0036] Note that a series of "circuits" such as the position circuit 107, the comparison circuit 108, the reference image creation circuit 112, the table control circuit 114, and the stage control circuit 140 comprise a processing circuit. Such processing circuits include an electric circuit, a computer, a processor, a circuit board, a quantum circuit, or a semiconductor device. Alternatively, different processing circuits (separate processing circuits) may be used. For example, a series of "circuits" such as the position circuit 107, the comparison circuit 108, the reference image creation circuit 112, the table control circuit 114, and the stage control circuit 140 may be configured and executed by the control computer 110. Input data or calculated results required for the position circuit 107, the comparison circuit 108, the reference image creation circuit 112, the table control circuit 114, and the stage control circuit 140 are stored in a memory (not shown) within each circuit or in the memory 111. Input data or calculated results required for the control computer 110 are stored in a memory (not shown) within the control computer 110 or in the memory 111. The program for causing the computer or processor to execute the program may be recorded on a recording medium such as the magnetic disk device 109 .

[0037] In the inspection device 100, a reflection inspection optical system with a high magnification M1 is configured by the light source 103, the Kohler illumination optical system 300, the relay lens 31, the beam splitter 32, the reflection illumination optical system 270, the beam splitter 176, the objective lens 104, the imaging optical system 178, the imaging sensor 105, and the sensor circuit 106. The inspection optical system has a magnification M1 of, for example, 200 to 300 times.

[0038] Drawing data (design data) that is the basis for forming a pattern on the inspected substrate 101 is input from outside the inspection device 100 and stored in the magnetic disk device 109. The drawing data defines a plurality of graphic patterns, and each graphic pattern is usually composed of a combination of a plurality of element graphics. However, a graphic pattern composed of a single graphic may also be present. On the inspected substrate 101, corresponding patterns are formed based on each graphic pattern defined in the drawing data.

[0039] 1 shows components necessary for explaining the first embodiment. It goes without saying that the inspection device 100 may include other components that are normally required.

[0040] The light source 103 generates, as inspection illumination light, for example, laser light (e.g., DUV light) (an example of ultraviolet light) with a wavelength of about 190 to 200 nm. By making the laser light 301 emitted from the light source 103 incident on the Koehler illumination optical system 300, inspection light that can ideally uniformly illuminate a surface is generated. Specifically, the operation is as follows. The laser light 301 emitted from the light source 103 is expanded by the beam expander 302, and a surface light source is generated by the lens array 304. Specifically, the lens array 304 is irradiated with the laser light 301 (inspection light) and splits the laser light 301 into multiple light beams. A surface light source is generated by the multiple split light beams. Thereafter, a Fourier plane of the surface light source is generated by the collimator lens 308, and an illumination slit 310 is positioned at the position of this Fourier plane.

[0041] The inspection light that passes through the illumination slit 310 is projected onto the beam splitter 32 by the relay lens 31. The beam splitter 32 splits the inspection light into light for measuring the light intensity and light for reflected illumination. The beam splitter 32 reflects 0.1 to 10% (for example, 1%) of the inspection light intensity toward the light intensity sensor 324, and transmits the remaining inspection light intensity toward the reflection optical system 270.

[0042] The light intensity sensor 324 receives a portion of the inspection light split by the beam splitter 32, measures the intensity of that portion of the inspection light, and converts it into the intensity of the entire inspection light, thereby measuring the intensity of the inspection light. It is also possible to simply measure the intensity of the received portion of the inspection light without converting it into the intensity of the entire inspection light.

[0043] 1, the amount of inspection light after passing through the Koehler illumination optical system 300 is measured, but the present invention is not limited to this. The amount of light may be measured at any position on the optical path from the light source 103 to the substrate 101. Therefore, the beam splitter 32 for branching part of the inspection light to the light amount sensor 324 side may be disposed on the optical path from the light source 103 to the substrate 101.

[0044] In the reflection inspection, the inspection light for reflection inspection that has passed through the beam splitter 32 is reflected by the beam splitter 176 and is irradiated onto the substrate 101 by the objective lens 104. In other words, the objective lens 104 irradiates the substrate 101 (mask substrate) on which a graphic pattern is formed with at least a portion of the multiple light beams split by the lens array 320. In yet other words, the illumination optical system consisting of the reflection illumination optical system 270, the beam splitter 176, and the objective lens 104 illuminates the inspected substrate 101 on which a pattern is formed. The reflected light from the substrate 101 passes through the objective lens 104 and the beam splitter 174 and is formed as an optical image (reflection image) by the imaging optical system 178 and enters the image sensor 105. In this way, the image sensor 105 captures an optical image (reflection image) of the substrate 101 obtained by illuminating the substrate 101.

[0045] The pattern image formed on the image sensor 105 is photoelectrically converted by each photosensor element of the image sensor 105, and the integrated value of the multiple photosensor elements arranged in the scanning direction is output to the sensor circuit 106. The sensor circuit 106 then performs A / D (analog-to-digital) conversion.

[0046] 2 is a conceptual diagram illustrating the inspection area in the first embodiment. As shown in FIG. 2, the inspection area 10 (the entire inspection area) of the substrate 101 is virtually divided, for example, in the Y direction, into a plurality of rectangular inspection stripes 20 each having a scan width W of the image sensor 105. The inspection device 100 then acquires an image (stripe area image) for each inspection stripe 20. For each inspection stripe 20, a laser beam (inspection light) is used to capture an image of the graphic pattern arranged within the inspection stripe 20 in the longitudinal direction (X direction) of the stripe area. Note that, to prevent missing images, the inspection stripes 20 are preferably set so that adjacent inspection stripes 20 overlap with each other by a predetermined margin width.

[0047] The movement of the XYθ table 102 causes the image sensor 105 to continuously move relatively in the X direction, thereby acquiring optical images. The image sensor 105 continuously captures optical images with a scan width W as shown in FIG. 2. In other words, the image sensor 105 captures optical images of the surface of the substrate 101 on which multiple graphic patterns are formed, while moving relatively in the integration direction of the image sensor 105. In the first embodiment, after capturing an optical image of one inspection stripe 20, the image sensor 105 moves in the Y direction to the position of the next inspection stripe 20, and then moves in the reverse direction while continuously capturing optical images with the scan width W in the same manner. In other words, imaging is repeated in the forward (FWD)-backward (BWD) directions, which are opposite directions on the outward and return paths.

[0048] Furthermore, in actual inspection, the stripe region image of each inspection stripe 20 is divided into a plurality of rectangular frame region 30 images, as shown in FIG. 2. Then, inspection is performed for each frame region 30 image. For example, it is divided into a size of 1024 x 1024 pixels. Therefore, a reference image to be compared with the frame image of the frame region 30 is also created for each frame region 30.

[0049] Here, the imaging direction is not limited to repeated forward (FWD)-backward (BWD). Imaging may be performed from one direction. For example, FWD-FWD may be repeated. Alternatively, BWD-BWD may be repeated.

[0050] FIG. 3 is a diagram illustrating the effect of a lens array in Comparative Example 1 of Embodiment 1. In FIG. 3 , in the comparative example, laser light 501 generated from a light source (not shown) is expanded by beam expander 502 and enters lens array 504. Then, multiple light beams formed as a surface light source by lens array 504 enter objective lens 506 via relay lens 505. Each light beam split by lens array 504, in which individual lenses are arranged at equal intervals, travels to objective lens 506 while repeatedly passing through an intermediate image plane. When each light beam split by lens array 504 is condensed and objective lens 506 is positioned at a position where the irradiated energy is concentrated, the irradiated light beams with concentrated irradiated energy are irradiated onto objective lens 506 for a long time, deteriorating objective lens 506 at each condensed position and changing the lens refractive index. Therefore, a phase grating with equal intervals is formed on objective lens 506. As shown in FIG. 3 , a phase grating is formed on objective lens 506 near the pupil plane of each light beam split by lens array 504.

[0051] FIG. 4 is a diagram for explaining the occurrence of a ghost image in Comparative Example 1 of Embodiment 1. FIG. 4 shows the path of an image of a mask substrate 508 illuminated by the objective lens 506 shown in FIG. 3 until it is captured by an imaging sensor 512. The examples of FIGS. 3 and 4 show reflection inspection. The reflected image of the mask substrate 508 illuminated by the objective lens 506 passes through the objective lens 506 and is formed on the imaging sensor 512 by an imaging lens 510. In this case, a portion of the reflected image is diffracted by a phase grating formed on the objective lens 506, becoming a ghost image (reflected image), which is then formed on the imaging sensor 512 by the imaging lens 510. A shift amount ΔY at which a ghost image occurs can be defined by the following equation (1) using the diffraction angle θ and the focal length f of the imaging lens. (1) ΔY=f tan(θ) The diffraction angle θ can be defined by the following equation (2) using the wavelength λ and the period p of the phase grating. (2) θ=λ / p Therefore, it is desirable to suppress the ghost image from appearing.

[0052] Fig. 5 is a diagram showing an example of a ghost image in Comparative Example 1 of Embodiment 1. The example of Fig. 5 shows an image of a cross mark formed on a mask substrate. The example of Fig. 5 shows a case where a ghost image is reflected below a line extending in the horizontal direction (x direction).

[0053] Fig. 6 is a diagram showing another example of a ghost image in Comparative Example 1 of Embodiment 1. The example of Fig. 6 shows an image of a cross mark formed on a mask substrate. The example of Fig. 6 shows a case where a ghost image is reflected above a line extending in the horizontal direction (x direction).

[0054] The period p of the phase grating described above depends on the arrangement pitch of the individual lenses in the lens array. Therefore, in the first embodiment, the lens array 304 is shifted at a predetermined timing to prevent each light beam with concentrated irradiation energy from being irradiated at the same position on the objective lens 104 for a long period of time. Alternatively, a method may be employed in which the period for shifting the lens array 304 is determined in advance. However, when shifting at a fixed time (period), the amount of illumination light per period is not necessarily constant. This is because the number of inspections of the mask substrate within a period may be large or small. When the number of inspections is large, the time during which each light beam with concentrated irradiation energy is irradiated naturally becomes longer. Therefore, the integrated amount of light increases. Conversely, when the number of inspections is small, the time during which each light beam with concentrated irradiation energy is irradiated becomes shorter. Therefore, the integrated amount of light decreases. Furthermore, the amount of light used varies depending on the reflectivity of the mask substrate to be inspected. Therefore, even when the lens array 304 is shifted at a fixed period, a phase grating may be formed.

[0055] Therefore, in the first embodiment, the timing for shifting the lens array 304 is not fixed, but is set to the time when the integrated light amount reaches a threshold value.

[0056] First, in the inspection device 100, calibration is performed and then the inspection process is started.

[0057] In the scanning process, the optical image capturing mechanism 150 uses the calibrated imaging sensor 105 to capture an image of the substrate 101, obtained by irradiating the substrate 101 with light (first light) that has passed through the beam splitter 32 for inspection illumination light, and outputs the captured optical image data. To achieve this, the optical image capturing mechanism 150 first scans the inspection stripes 20 with laser light (inspection light), and captures an image of the stripe region for each inspection stripe 20 using the imaging sensor 105. Specifically, the operation is as follows: The XYθ table 102 is moved to a position where the target inspection stripe 20 can be imaged. In the reflection inspection, light reflected from the substrate 101 is focused as an optical image on the imaging sensor 105.

[0058] The image of the pattern formed on the image sensor 105 is photoelectrically converted by each photosensor element of the image sensor 105 and is further A / D (analog-to-digital) converted by a sensor circuit 106 .

[0059] The gradation value (image data) of each pixel is output to a stripe pattern memory 123.

[0060] Then, pixel value data of the inspection stripe 20 to be measured is stored in the stripe pattern memory 123. The measurement data (pixel data) is, for example, 8-bit unsigned data, and represents the brightness gradation (light amount) of each pixel. The pixel value data of the inspection stripe 20 is output to the comparison circuit 108.

[0061] In the comparison step, the presence or absence of defects is inspected by performing a comparison process in the comparison circuit 108 as will be described later.

[0062] When the inspection process of all the inspection stripes 20 that are the inspection areas of the target substrate 101 is completed, the process proceeds to the inspection process of the next substrate 101. For example, the inspection of one substrate 101 is completed in one to several hours. During that time, the objective lens 104 continues to be irradiated with the respective lights with concentrated irradiation energy at the same position for a long time.

[0063] In the light intensity measurement step, the light intensity sensor 324 continues to measure the intensity of the inspection light while the inspection process is being performed on at least one substrate 101. Alternatively, the light intensity sensor 324 measures the intensity of the inspection light at a predetermined sampling interval, such as several μs to several seconds. The light intensity measured by the light intensity sensor 324 is output to the stage control circuit 140.

[0064] In the lens array shifting step, the stage control circuit 140 (controller) controls the lens array stage 320 to change the position of the lens array 304 when the measured integrated light amount is equal to or greater than a threshold. The lens array stage 320 moves in a direction parallel to a plane perpendicular to the optical axis of the inspection light. When the measured integrated light amount is equal to or greater than a threshold, the stage control circuit 140 controls the lens array stage 320 to shift the position of the lens array 304 by translation.

[0065] From the value V measured by the light intensity sensor 324, the intensity F of the light incident on the objective lens 104 can be defined by the following equation (3): where k is a proportionality coefficient. (3) F=k V Furthermore, the amount of light can be calculated by multiplying the intensity F of the incident light by the time. Therefore, the integrated amount of light F' incident on the objective lens 104 can be defined by the following equation (4). (4) F' = Σ(F × time)

[0066] Then, the stage control circuit 140 shifts the lens array 304 when the integrated light amount F' becomes equal to or greater than the threshold value Th. It is expected that inspection processes for a plurality of substrates 101 will be performed before the integrated light amount F' reaches the threshold value Th. For this reason, the lens array 304 is not shifted during the inspection of each substrate 101, but is shifted between the inspection process of one substrate 101 and the inspection process of the next substrate 101. When the lens array 304 is shifted, the integrated light amount F' is reset to zero, and the light amount is similarly accumulated from the next inspection process onwards.

[0067] FIG. 7 is a front view showing an example of the configuration of the lens array according to the first embodiment. FIG. 8 is a side view showing an example of the configuration of the lens array according to the first embodiment. 7 and 8 show a lens array 304 in which, for example, 5 × 5 individual lenses 33 are arrayed at a pitch P. On an intermediate image plane where light is collected by the individual lenses 33 to form a surface light source, the respective condensing points 34 (intermediate images) are arranged at a pitch P as shown in the right diagram of FIG. 8. If the magnification is the same, the respective intermediate images (condensing points) are similarly arranged at a pitch P near the pupil plane on the objective lens 104. In the first embodiment, the corresponding condensing points 34 (intermediate images) are controlled to move within a shift region 36 surrounded by four adjacent condensing points 34 (intermediate images) before forming irradiation marks (degraded portions) on the objective lens 104 that are deteriorated to the extent that they constitute a phase grating. The other condensing points 34 (intermediate images) are also similar in that they move within the shift region 36 containing the condensing points 34 (intermediate images) themselves before forming deteriorated portions on the objective lens 104.

[0068] 9 is a diagram showing an example of the shift position of the lens array in the first embodiment. The example of FIG. 9 shows an example of the shift order of one of the plurality of light-focusing points 34 (intermediate images) formed by the lens array 304. The plurality of individual lenses 33 constituting the lens array 304 are moved as a unit by the lens array stage 320. Therefore, the irradiated position within each shift region 36 is the same for each light.

[0069] The shift area 36 is divided in the x and y directions by the beam size at the focal point 34, and the shift results in a plurality of mesh-like small areas, for example, which become the plurality of positions to be irradiated with the light from the focal point by the shift. In the first embodiment, the order in which the plurality of small areas are irradiated is determined randomly. In other words, the shift area 36 is moved randomly. The example in FIG. 9 shows a case in which the shift is performed in the order of near the right center of the shift area 36 the first time, the upper left the second time, the lower right the third time, slightly below the upper right the fourth time, and slightly above the lower left the fifth time. The focal point 34 (intermediate image) is also shifted to each of the remaining positions in the shift area 36 in one of the orders from the sixth time onwards.

[0070] FIG. 10 is a diagram showing an example of a plurality of focal points on an objective lens in a first comparative example of the first embodiment. FIG. 11 is a diagram showing an example of a plurality of focal points on the objective lens after one shift cycle has been completed in the first embodiment. The example in Fig. 10 shows a case where a lens array 304 in which 5 x 5 individual lenses 33 are arranged in an array is used. After light is collected by each individual lens 33 to form a surface light source, each light collection point 12 (intermediate image) is arranged at a predetermined pitch on the objective lens 104 arranged near the pupil plane. If irradiation continues for a long time in this state, each irradiation position on the objective lens 104 deteriorates, and irradiation marks are formed at equal intervals. As a result, a phase grating is formed by these irradiation marks.

[0071] In contrast, in the first embodiment, as described above, the lens array 304 is shifted each time the integrated light amount reaches a threshold value, thereby shifting each irradiation position of the objective lens 104. By randomly shifting the focal point 34 (intermediate image) to each position within each shift region 36, when the first shift cycle is completed, the entire area surrounding the plurality of focal points 12 on the objective lens 104 is filled with the focal points 12, as shown in FIG. 11 . This makes it possible to prevent the formation of irradiation marks on the objective lens 104. Alternatively, even if irradiation marks are formed on the objective lens 104, they can be made to be weak and uniform. This makes it possible to avoid the formation of irradiation marks at equal intervals as shown in FIG. 10 . As a result, it is possible to avoid the formation of a phase grating.

[0072] FIG. 12 is a diagram showing an example of the shift order of the lens array in Comparative Example 2 of Embodiment 1. The example in FIG. 12 shows, for example, a case where the lens array is shifted sequentially in the vertical direction at fixed time intervals (periods). If the lenses are shifted sequentially in a fixed direction, as shown in FIG. 12, linear irradiation marks are formed that are strongly influenced by the arrangement pitch P of the multiple individual lenses that make up the lens array 304. As a result, a phase grating with a period equal to the arrangement pitch P may be formed. In contrast, in Embodiment 1, the shift position changes randomly each time the integrated light amount reaches a threshold value. Therefore, even if irradiation marks are formed, the irradiation marks can be made to be non-periodic. Therefore, the formation of a phase grating can be suppressed.

[0073] In the above example, the lens array 304 is shifted by translation, but the present invention is not limited to this.

[0074] Fig. 13 is a front view showing an example of the position of the lens array before and after shifting in a modification of the first embodiment. The example in Fig. 13 shows a lens array 304 in which, for example, 5 x 5 individual lenses 33 are arranged in an array. In the modification of the first embodiment, as a lens array shifting step, the lens array stage 320 rotates in a plane perpendicular to the optical axis of the inspection light. As shown in Fig. 13, the stage control circuit 140 (controller) controls the lens array stage 320 to shift the position of the lens array 304 by rotation when the measured integrated light amount becomes equal to or greater than a threshold.

[0075] 14 is a diagram showing an example of a plurality of focal points before and after shifting in a modification of the first embodiment. The example in FIG. 14 shows the positions of the focal points on the objective lens 104. By shifting the position of the lens array 304 by rotation, the positions of the plurality of focal points 12 on the objective lens 104 can be shifted in the rotation direction. This makes it possible to prevent the formation of strong irradiation marks on the objective lens 104 that would result in the formation of a phase grating. Alternatively, even if irradiation marks are formed on the objective lens 104, weak irradiation marks that do not have a predetermined period can be formed.

[0076] Here, when rotating, it is preferable to position the rotation center so that it does not coincide with the center of any of the individual lenses 33. In other words, it is preferable to configure the centers of all the individual lenses 33 so that they do not coincide with the rotation center for the rotation. This makes it possible to shift the positions of all of the multiple light-focusing points 12 by rotation.

[0077] In the above examples, the lens array 304 is shifted by translation or rotation, but the present invention is not limited to this. The lens array 304 may be shifted by a combination of translation and rotation.

[0078] Furthermore, when shifting the lens array 304 by translation and / or rotation, it is not limited to step movement. Shifting by continuous movement is also possible. When shifting by continuous movement, it is preferable to control the movement speed so that it is proportional to the amount of light incident on the objective lens 104. Since the amount of light can be defined as the intensity of incident light multiplied by time, the amount of light is proportional to the intensity of incident light divided by the movement speed. If the intensity of incident light is doubled, doubling the speed can make the amount of light approximately the same as when the intensity of incident light is 1 and the speed is 1.

[0079] Next, a supplementary explanation will be given of the operation of the inspection process described above: In parallel with the scanning process, a reference image creation process is carried out.

[0080] In the reference image creation process, the reference image creation circuit 112 uses graphic pattern data (design data) to create a reference image that serves as a reference. The creation of the reference image is performed for each inspection stripe 20 in parallel with the scanning operation of that inspection stripe 20. Specifically, the operation is as follows: The reference image creation circuit 112 inputs graphic pattern data (design data) for each frame region 30 of the target inspection stripe 20, and converts each graphic pattern defined in the graphic pattern data into binary or multi-value image data.

[0081] The figures defined in the figure pattern data are, for example, rectangles or triangles as basic figures, and the figure data stored defines the shape, size, position, etc. of each pattern figure using information such as the coordinates (x, y) at the reference position of the figure, the length of the sides, and a figure code that serves as an identifier to distinguish between figure types such as rectangles and triangles.

[0082] When the design pattern data that becomes such graphic data is input to the reference image creation circuit 112, it is expanded into data for each graphic, and the graphic code and graphic dimensions that indicate the graphic shape of the graphic data are interpreted. Then, it is expanded into binary or multi-valued design pattern image data as a pattern to be arranged in a grid with a predetermined quantized dimension as a unit, and output. In other words, the design data is read, the frame area is virtually divided into grids with a predetermined dimension as a unit, and the occupancy rate of the graphic in the design pattern is calculated for each grid, and n-bit occupancy data (design image data) is output. For example, it is preferable to set one grid as one pixel. Then, 1 / 2 is assigned to one pixel. 8 If a pixel has a resolution of (=1 / 256), a small area of ​​1 / 256 is allocated to the area of ​​the figure placed within the pixel, and the occupancy rate within the pixel is calculated. This is then created as 8-bit occupancy data. The grid (inspection pixel) can be aligned with the pixels of the measurement data.

[0083] Next, the reference image creation circuit 112 performs filtering using a filter function on the design image data of the design pattern, which is image data of the graphic.

[0084] FIG. 15 is a diagram illustrating the filtering process in the first embodiment. The pixel data of the optical image captured from the substrate 101 is filtered according to the resolution characteristics of the optical system used for capturing the image, in other words, is in a continuously changing analog state. Therefore, as shown in FIG. 15, the image intensity (gray value) differs from that of the expanded image (design image), which has a digital value. On the other hand, as described above, the figure pattern data is defined by a figure code, and therefore the image intensity (gray value) of the expanded design image may be a digital value. Therefore, the reference image creation circuit 112 performs image processing (filtering) on ​​the expanded image to create a reference image that approximates the optical image. This allows the design image data, which is image data on the design side with a digital image intensity (gray value), to be matched to the image generation characteristics of the measurement data (optical image). The created reference image is output to the comparison circuit 108.

[0085] FIG. 16 is a diagram showing an example of the internal configuration of a comparison circuit according to the first embodiment. In FIG. 16, comparison circuit 108 includes storage devices 70, 72, and 76, such as magnetic disk devices, a frame image creation unit 74, an alignment unit 78, and a comparison processing unit 79. A series of "units" such as frame image creation unit 74, alignment unit 78, and comparison processing unit 79 each have a processing circuit. Such processing circuits include an electric circuit, a computer, a processor, a circuit board, a quantum circuit, or a semiconductor device. Each "unit" may share a common processing circuit (the same processing circuit), or may use different processing circuits (separate processing circuits). Input data or calculation results required for frame image creation unit 74, alignment unit 78, and comparison processing unit 79 are stored in a memory (not shown) within comparison circuit 108 or in memory 111, as needed.

[0086] The stripe data (stripe area image) input to the comparison circuit 108 is stored in the storage device 70. The reference image data input to the comparison circuit 108 is stored in the storage device 72.

[0087] In the comparison step (S140), the comparison circuit 108 (an example of a comparison unit) compares the inspection image using the image data with a predetermined image. Specifically, the operation is as follows.

[0088] In the comparison circuit 108, the frame image creation unit 74 first generates a plurality of frame images 31 by dividing the stripe region image (optical image) at a predetermined width. Specifically, as shown in FIG. 2, the stripe region image is divided into a plurality of rectangular frame region 30 frame images. For example, the size is divided into 1024 x 1024 pixels. Data for each frame region 30 is stored in the storage device 76.

[0089] Next, the alignment unit 78 reads out the corresponding frame image 31 and the corresponding reference image for each frame region 30 from the storage devices 72, 76, and aligns the frame image 31 with the corresponding reference image using a predetermined algorithm. For example, alignment is performed using the least squares method.

[0090] Then, the comparison processing unit 79 (another example of a comparison unit) compares the frame image 31 with the reference image corresponding to that frame image 31. For example, it compares them pixel by pixel. Here, the two are compared pixel by pixel according to predetermined judgment conditions to determine whether or not there is a defect, such as a shape defect. The judgment conditions may, for example, be to compare the two pixel by pixel according to a predetermined algorithm to determine whether or not there is a defect. For example, the difference between the pixel values ​​of the two images is calculated for each pixel, and if the difference value is greater than a threshold value Th, it is determined that there is a defect. The comparison results may then be output, for example, to the magnetic disk device 109, or a pattern monitor (not shown), or from a printer (not shown).

[0091] Although the above example describes the case of die-to-database inspection, die-to-die inspection may also be used. In this case, for the frame regions 30 among the plurality of frame regions 30 for which die-to-die inspection is performed, the comparison circuit 108 uses the frame image (optical image) of die 2 acquired for one of the frame regions as a reference (reference image). First, for each frame region 30 for which die-to-die inspection is performed, the alignment unit 78 reads the frame image 31 of die 1 and the frame image of die 2 corresponding to the frame region 30 for which die-to-die inspection is performed from the storage device 76, and aligns the frame image 31 of die 1 with the frame image of die 2 using a predetermined algorithm. For example, the least squares method is used for alignment. Then, the comparison processing unit 79 (comparison unit) compares the frame image 31 of die 1 with the frame image of die 2 for each frame region 30 for which die-to-die inspection is performed, pixel by pixel. For example, a pixel-by-pixel comparison is performed. Here, the two are compared pixel by pixel according to predetermined judgment conditions to determine the presence or absence of defects, such as shape defects. The comparison result may then be output to, for example, the magnetic disk device 109, or a pattern monitor (not shown), or may be output from a printer (not shown).

[0092] As described above, according to the first embodiment, it is possible to prevent a phase grating from being formed on an optical element such as the objective lens 104. Therefore, it is possible to prevent diffraction due to the phase grating. Therefore, it is possible to prevent ghost images from being reflected. As a result, it is possible to prevent the detection of false defects.

[0093] Embodiment 2 In the first embodiment, a configuration has been described in which the lens array 304 is slightly shifted to shift the position of the focal point. The method of suppressing the formation of a phase grating is not limited to this. In the second embodiment, an inspection device equipped with multiple lens arrays will be described. Furthermore, points that are not specifically explained below are the same as those in the first embodiment.

[0094] Fig. 17 is a configuration diagram showing the configuration of a pattern inspection apparatus according to embodiment 2. Fig. 17 is the same as Fig. 1 except that a lens array 304-1 (first lens array) and a lens array 304-2 (second lens array) are arranged on a lens array stage 320.

[0095] FIG. 18 is a side view showing an example of a plurality of lens arrays according to the second embodiment. In FIG. 18, lens array 304-1 is irradiated with inspection light and splits the inspection light into multiple beams. Similarly, lens array 304-2 is irradiated with inspection light and splits the inspection light into multiple beams. Lens array 304-2 has a different lens arrangement pitch from lens array 304-1. In the example shown in FIG. 18, lens array 304-1 is arranged at an arrangement pitch P1, and lens array 304-2 is arranged at an arrangement pitch P2 that is, for example, smaller than the arrangement pitch P1. Because the arrangement pitches of the individual lenses 33 are different, it is possible to prevent a light convergence point 34-1 formed by lens array 304-1 and a light convergence point 34-2 formed by lens array 304-2 from overlapping.

[0096] The lens array stage 320 supports the lens array 304-1 and the lens array 304-2, and is arranged to be movable within a plane perpendicular to the optical axis of the inspection light.

[0097] For example, first, lens array 304-1 is placed on the optical path.

[0098] As a scanning process, the optical image acquisition mechanism 150 uses the calibrated imaging sensor 105 to capture an image of the substrate 101 obtained by irradiating the substrate 101 on which a pattern is formed with light (first light) that has passed through the beam splitter 32 for inspection illumination light, and outputs the captured optical image data.

[0099] The image of the pattern formed on the image sensor 105 is photoelectrically converted by each photosensor element of the image sensor 105 and is further A / D (analog-to-digital) converted by a sensor circuit 106 .

[0100] The gradation value (image data) of each pixel is output to a stripe pattern memory 123.

[0101] Then, pixel value data of the inspection stripe 20 to be measured is stored in the stripe pattern memory 123. The pixel value data of the inspection stripe 20 is output to the comparison circuit .

[0102] In the comparison step, similarly to the first embodiment, a comparison process is performed in the comparison circuit 108 to check for the presence or absence of defects.

[0103] When the inspection process of all the inspection stripes 20 that are the inspection areas of the target substrate 101 is completed, the process proceeds to the inspection process of the next substrate 101. For example, the inspection of one substrate 101 is completed in one to several hours. During that time, the objective lens 104 continues to be irradiated with the respective lights with concentrated irradiation energy at the same position for a long time.

[0104] In the light intensity measurement step, the light intensity sensor 324 continues to measure the intensity of the inspection light while the inspection process is being performed on at least one substrate 101. Alternatively, the light intensity sensor 324 measures the intensity of the inspection light at a predetermined sampling interval, such as several μs to several seconds. The light intensity measured by the light intensity sensor 324 is output to the stage control circuit 140.

[0105] In the lens array shifting step, when the measured integrated light amount becomes equal to or greater than a threshold value, the stage control circuit 140 (controller) controls the lens array stage 320 to switch the lens array irradiated with the inspection light from one of the lens array 304-1 and the lens array 304-2 to the other. Here, for example, the lens array 304-1 is switched to the lens array 304-2. When the measured integrated light amount becomes equal to or greater than a threshold value, the stage control circuit 140 controls the lens array stage 320 to switch the lens array by translating the position of the lens array 304.

[0106] Then, when the lens array is switched, the integrated light amount F' is reset to zero, and the light amount is integrated in the same manner from the next inspection process onwards. Therefore, the objective lens 104 irradiates the substrate 101 on which the graphic pattern is formed with at least some of the multiple light beams split by either the lens array 304-1 or the lens array 304-2.

[0107] Then, when the measured integrated light amount again becomes equal to or greater than the threshold value, for example, the lens array 304-2 is switched to the lens array 304-1.

[0108] In the second embodiment, as described above, the lens array is switched to another lens array with a different arrangement pitch each time the integrated light amount reaches a threshold value. This shifts the irradiation position of each objective lens 104. As a result, it is possible to prevent the formation of irradiation marks on the objective lens 104. Alternatively, even if irradiation marks are formed on the objective lens 104, they are weak, and it is possible to suppress the formation of irradiation marks strong enough to form a phase grating. As a result, it is possible to avoid the formation of a phase grating. This suppresses diffraction by the phase grating. Therefore, it is possible to suppress the reflection of ghost images. As a result, it is possible to suppress the detection of false defects.

[0109] Embodiment 3 In the above-described embodiments, a configuration for preventing or making it difficult for a phase grating to be formed has been described. In embodiment 3, a configuration for suppressing or reducing reflections caused by a phase grating after the phase grating has been formed will be described. Furthermore, points that are not particularly described below are the same as embodiment 1.

[0110] Fig. 19 is a configuration diagram showing the configuration of a pattern inspection apparatus according to embodiment 3. Fig. 19 is the same as Fig. 1 except that a lens array position control circuit 142 is added. In Fig. 19, the beam splitter 32 and the light intensity sensor 324 may be omitted.

[0111] FIG. 20 is a block diagram showing an example of the internal configuration of the lens array position control circuit according to the third embodiment. In FIG. 20, lens array position control circuit 142 includes storage devices 50, 53, 56, and 60, such as magnetic disk devices, reflection gradation value calculation unit 51, recording processing unit 52, determination unit 54, recording processing unit 55, determination unit 57, shift processing unit 58, sorting processing unit 59, and order determination unit 61. Each of the "~ units" including reflection gradation value calculation unit 51, recording processing unit 52, determination unit 54, recording processing unit 55, determination unit 57, shift processing unit 58, sorting processing unit 59, and order determination unit 61 has a processing circuit. Such a processing circuit may include an electric circuit, a computer, a processor, a circuit board, a quantum circuit, or a semiconductor device. Each of the "~ units" may share a common processing circuit (the same processing circuit), or may use different processing circuits (separate processing circuits). The input data or calculated results required for the reflection gradation value calculation unit 51, recording processing unit 52, judgment unit 54, recording processing unit 55, judgment unit 57, shift processing unit 58, sorting processing unit 59, and order determination unit 61 are stored each time in a memory (not shown) within the lens array position control circuit 142 or in memory 111.

[0112] Fig. 21 is a flowchart showing an example of main steps of the inspection method according to embodiment 3. In Fig. 21, the inspection method according to embodiment 3 carries out a series of steps, namely, an inspection process step (S100), a mark scanning process step (S108), a reflection gradation value calculation process (S110), a recording process step (S112), a determination process (S114), a recording process step (S116), a determination process (S118), a lens array shifting process (S120), a sorting process step (S130), and an order determination process (S132).

[0113] As internal steps of the inspection processing step (S100), a series of steps including a scanning step (S102), a reference image creation step (S104), and a comparison step (S106) are carried out.

[0114] As the inspection process step (S100), the inspection process is performed in the inspection device 100 with the lens array 304 set at a predetermined position. As described in the first embodiment, the lens array 304 has its irradiation positions sequenced so as to randomly irradiate each position within the shift area 36, ​​and therefore, here, the inspection process is started with the lens array 304 set at the initial position.

[0115] In the scanning process (S102), the optical image acquisition mechanism 150 captures an image of the substrate 101 obtained by irradiating the substrate 101 on which a pattern is formed with inspection illumination light (first light) using the imaging sensor 105, and outputs the captured optical image data.

[0116] The image of the pattern formed on the image sensor 105 is photoelectrically converted by each photosensor element of the image sensor 105 and is further A / D (analog-to-digital) converted by a sensor circuit 106 .

[0117] The gradation value (image data) of each pixel is output to a stripe pattern memory 123.

[0118] Then, pixel value data of the inspection stripe 20 to be measured is stored in the stripe pattern memory 123. The measurement data (pixel data) is, for example, 8-bit unsigned data, and represents the brightness gradation (light amount) of each pixel. The pixel value data of the inspection stripe 20 is output to the comparison circuit 108. The contents of the scanning step (S102) are the same as those in the first embodiment.

[0119] In the reference image creation step (S104), the reference image creation circuit 112 creates a reference image to serve as a reference using graphic pattern data (design data). The creation of the reference image is performed for each inspection stripe 20 in parallel with the scanning step (S102) of that inspection stripe 20. The content of the reference image creation step (S104) is the same as in the first embodiment.

[0120] In the comparison step (S106), the comparison circuit 108 compares the frame image 31 (image to be inspected) using the image data with the reference image (predetermined image). The details of the comparison step (S106) are the same as those in the first embodiment.

[0121] When the inspection process for all the inspection stripes 20 that are the inspection areas of the target substrate 101 has been completed, the process proceeds to the mark scanning step (S108).

[0122] In the mark scanning step (S108), an image of the substrate 101, on which a mark pattern is formed, is captured by the imaging sensor 105 by irradiating the substrate 101 with inspection illumination light (first light), and the captured optical image data is output. In other words, the optical image acquisition mechanism 150 captures an image of the mark, obtained by scanning the mark formed on the substrate 101, by the imaging sensor 105, and outputs the captured optical image data.

[0123] FIG. 22 is a top view showing an example of a mask substrate in the third embodiment. In FIG. 22, a plurality of mark patterns 11 are formed around a central pattern formation region 13 on a substrate 101. The example of FIG. 22 shows a case where a mark pattern 11 is formed at each of the four corners of the pattern formation region 13. The position of the mark pattern 11 is not limited to this. The mark pattern 11 may also be formed within the pattern formation region 13. It is preferable to use a cross-shaped graphic pattern as the mark pattern 11.

[0124] In the mark scanning step (S108), an image of a preset position of the mark pattern 11 is acquired. In the example of FIG. 22, it is preferable to acquire an image of an area including two pixels 37 that straddle both edges of the vertical lines that form the cross shape, and two pixels 37 that straddle both edges of the horizontal lines. For example, it is preferable to set this to an image of the same size as the frame area 30. Alternatively, an image of an area size larger or smaller than the frame area 30 may be used.

[0125] The image of the pattern formed on the image sensor 105 is photoelectrically converted by each photosensor element of the image sensor 105 and is further A / D (analog-to-digital) converted by a sensor circuit 106 .

[0126] The gradation value (image data) of each pixel is output to a stripe pattern memory 123.

[0127] Then, pixel value data of the mark image to be measured is stored in stripe pattern memory 123. The measurement data (pixel data) is, for example, 8-bit unsigned data, and represents the brightness gradation (light amount) of each pixel. The pixel value data of the mark image is output to lens array position control circuit 142.

[0128] The pixel value (grayscale value) data of the mark image input into the lens array position control circuit 142 is stored in the storage device 50.

[0129] In the reflection gradation value calculation step (S110), the reflection gradation value calculation unit 51 calculates the gradation value of a ghost image reflected in the mark image. Specifically, a difference value is calculated by subtracting the gradation value of the pixel straddling the edge portion of the captured mark pattern shown in FIG. 22 from the gradation value of the pixel at the same position in a reference mark image where no ghost image occurs. Since the mark image obtained in the first mark scanning step (S108) after shifting the lens array 304 does not yet have any ghost image reflection, it is preferable to use this mark image as the reference mark image. Therefore, in the first reflection gradation value calculation step (S110), the captured mark image becomes the reference mark image, and the gradation value of the ghost image becomes zero. With the lens array 304 in the same position, a difference value may be generated in the second reflection gradation value calculation step (S110).

[0130] Alternatively, there may be cases where no ghost image reflection occurs in the first cycle of shifting each position within the shift area 36. As this process is repeated for the second, third, and so on cycle, deterioration progresses at each light irradiation position on the objective lens 104, and ghost image reflection occurs.

[0131] In the example of FIG. 22, pixels including the edge portion of the mark pattern 11 are used, but this is not limiting. The gradation value of the ghost image may also be calculated using pixels adjacent to pixels including the edge portion of the mark pattern 11. If a ghost image is reflected, the pixel value is expected to change. If the mark pattern is a white pattern, the gradation value of the pixel including the ghost image will be larger than the gradation value of the same pixel in the reference mark image. If the mark pattern is a black pattern, the gradation value of the pixel including the ghost image will be smaller than the gradation value of the same pixel in the reference mark image.

[0132] In the recording process step (S112), the recording processing unit 52 records the calculated gradation value of the ghost image (reflection gradation value) in the storage device 53 in association with the arrangement position coordinates of the lens array 304.

[0133] In the determination step (S114), the determination unit 54 determines whether the elapsed time T from the time when the lens array 304 was last shifted to the present time has reached a threshold value Tth. The threshold value Tth is preferably set to, for example, 10 to 50 hours. If the elapsed time T has not reached the threshold value Tth, the process returns to the inspection process step (S100), and each step from the inspection process step (S100) to the determination process (S114) is repeated for each different substrate 101 until the elapsed time T reaches the threshold value Tth. If the elapsed time T has reached the threshold value Tth, the process proceeds to the recording process step (S118).

[0134] As a result, for multiple substrates 101 whose images are captured using the lens array 304 with the same shift position, the gradation value of the ghost image (reflection gradation value) is recorded each time the inspection process for each substrate 101 is completed.

[0135] Here, among the multiple mark images captured at different times, the mark image captured immediately before it is determined in the determination step (S114) that the elapsed time T has reached the threshold value Tth is the image captured in a state where the light beams with concentrated irradiation energy were irradiated for the longest time at the same position on the objective lens 104. Therefore, the ghost image may be most strongly reflected in the mark image captured last with the lens array 304 at the same position.

[0136] In the recording process step (S116), the recording processing unit 55 uses the captured mark image (an example of an optical image) to record the gradation value of the ghost image of a pixel (position) that is set in advance for the image of the mark pattern (figure pattern) for each position of the lens array 304. Specifically, the recording processing unit 55 records the gradation value (reflection gradation value) of the ghost image that was last recorded among the gradation values ​​(reflection gradation values) of the multiple ghost images recorded in the storage device 53 for each position of the lens array 304 in a movement table in association with the arrangement position coordinates of the lens array 304, and stores the movement table in the storage device 56. The recording processing unit 55 is an example of a movement table creation unit.

[0137] In the determination step (S118), the determination unit 57 determines whether shifting has been completed to all positions within the shift area 36. In the third embodiment, shifting is performed once to all positions within the shift area 36 in a random order. When shifting has been completed to all positions within the shift area 36, ​​one cycle of shifting has been completed for each position within the shift area 36. In other words, the determination unit 57 determines whether the kth cycle of shifting has been completed. If the kth cycle of shifting has been completed, the process proceeds to the sorting process step (S130). If the kth cycle of shifting has not yet been completed, the process proceeds to the lens array shifting step (S120).

[0138] In the lens array shifting step (S120), the shift processing unit 58 controls the stage control circuit 140 to shift the position of the lens array 304 to the next position. The stage control circuit 140 (control unit) controls the lens array stage 320 to shift the position of the lens array 304 to the next position under predetermined conditions. Here, for example, the position of the lens array 304 is shifted to the next position every time the elapsed time T reaches the threshold value Tth. The lens array 304 is shifted so that the focal points 12 of the divided light beams irradiate each position in the corresponding shift region 36 once in a random order.

[0139] After each shift, the process returns to the inspection process step (S100), and the steps from the inspection process step (S100) to the lens array shift step (S120) are repeated until the kth shift is completed in the determination step (S118).

[0140] As a result of the above, for each position of the shifted lens array 304, the gradation value of the ghost image (reflection gradation value) is recorded in the movement table in association with the arrangement position coordinates of the lens array 304.

[0141] FIG. 23 is a diagram showing an example of a shift table in the third embodiment. The shift table defines a correlation between the reflection gradation value, the x-value of the coordinate of the lens array 304, and the y-value of the coordinate of the lens array 304. The example of FIG. 23 shows a case where the coordinates of each position in the x and y directions within the shift area 36 are defined with a resolution of 1024 gradations. For example, it is shown that when the lens array 304 is placed at coordinates (512, 777), the reflection gradation value becomes 5.5. It is also shown that when the lens array 304 is placed at coordinates (478, 677), the reflection gradation value becomes 3.2. It is also shown that when the lens array 304 is placed at coordinates (299, 512), the reflection gradation value becomes 1.3.

[0142] In the sorting process step (S130), the sorting unit 59 sorts the gradation values ​​of the ghost images recorded at each position of the lens array 304 in the kth cycle in ascending order.

[0143] FIG. 24 is a diagram showing an example of a translation table after sorting in the third embodiment. In the translation table, the reflection gradation value is defined so as to be associated with the x value of the coordinate of the lens array 304 and the y value of the coordinate of the lens array 304. In the example of FIG. 24, it can be seen that the coordinate of the lens array 304 at the smallest reflection gradation value, for example, 1.1, is (246,642). It can also be seen that the coordinate of the lens array 304 at the second smallest reflection gradation value, for example, 1.3, is (299,512). The translation table (sort data) after sorting is stored in the storage device 60.

[0144] In the order determination step (S132), the order determination unit 61 determines the order in which the lens array 304 is to be moved next, by prioritizing the positions of the lens array 304 corresponding to smaller gradation values ​​of the ghost images recorded at each position of the k-th cycle of the lens array 304 over the positions of the lens array 304 corresponding to larger gradation values. Specifically, the order determination unit 61 determines the order in which the lens array 304 is to be moved next, in order of increasing gradation values ​​of the ghost images.

[0145] Then, the process proceeds to the lens array shifting step (S120). In the lens array shifting step (S120), the lens array 304 is shifted in the determined order for the (k+1)th shift position, and the process returns to the inspection processing step (S100). In the determination step (S118), the inspection processing step (S100) to the lens array shifting step (S120) are repeated until the (k+1)th shift is completed.

[0146] As a result, for each position of the lens array 304 in the (k+1)th cycle, the gradation value of the ghost image (reflection gradation value) is recorded in the movement table in association with the arrangement position coordinates of the lens array 304. Thereafter, the sorting process step (S130) and the order determination step (S132) are similarly performed to determine the order for the (k+2)th cycle. Thereafter, each step is similarly repeated.

[0147] In the above example, the elapsed time T is used as the timing for shifting, but this is not limiting. It is also possible to shift the phase grating each time the integrated light amount reaches a threshold, as described in the first and second embodiments. In this case, as described in the first and second embodiments, it is more difficult to form a phase grating than when the shift is performed based on the elapsed time T. Therefore, it is possible that no ghost image reflection occurs during the first to several cycles in which each position within the shift region 36 is shifted once. As this is repeated 10 times, 20 times, and so on, deterioration progresses at each light irradiation position on the objective lens 104, and ghost image reflection may occur.

[0148] FIG. 25 is a diagram showing an example of the relationship between the shift position and the reflection intensity in the third embodiment. FIG. 26 illustrates another example of the relationship between shift position and reflection intensity in the third embodiment. As described above, when shifting at fixed intervals (periods), the illumination light intensity for each period is not necessarily constant. Furthermore, the amount of light used varies depending on the reflectivity of the mask substrate to be inspected. Therefore, even when the lens array 304 is shifted at fixed intervals, a phase grating may be formed. For example, after the first shift cycle is completed, as shown in FIG. 25, some positions have strong reflection intensity of the ghost image and others have weak reflection intensity, depending on the shift position, resulting in variations in reflection intensity. In contrast, by shifting the lens array 304 preferentially to positions with small gradation values ​​of the ghost image (reflection gradation values), as in the third embodiment, the reflection intensity of the ghost image at each position can be made uniform, or can be made nearly uniform, as shown in FIG. 26. As a result, the periodicity is eliminated, and the formation of a phase grating can be eliminated.

[0149] As described above, according to the third embodiment, even if ghost images are reflected, the periodicity of the phase grating can be eliminated, and the ghost images can be suppressed or reduced.

[0150] Embodiment 4 In the third embodiment, a configuration has been described in which the order of the shift positions in each cycle, where one shift to each position in the shift area 36 is made, is in ascending order of the gradation value of the ghost image, but this is not limiting. In the fourth embodiment, a different configuration will be described.

[0151] The configuration of the inspection device 100 in the fourth embodiment is the same as that shown in Fig. 19. In addition, the contents other than those particularly explained below are the same as those in the third embodiment. As in the third embodiment, the beam splitter 32 and the light intensity sensor 324 may be omitted.

[0152] Fig. 27 is a block diagram showing an example of the internal configuration of the lens array position control circuit in embodiment 4. Fig. 27 is the same as Fig. 20 except that, instead of sorting processing unit 59, storage device 60, and order determination unit 61, an extraction unit 65, storage device 66, order determination unit 67, and determination unit 68 are arranged in lens array position control circuit 142. A series of "units" such as the reflection gradation value calculation unit 51, the recording processing unit 52, the determination unit 54, the recording processing unit 55, the determination unit 57, the shift processing unit 58, the extraction unit 65, the order determination unit 67, and the determination unit 68 each have a processing circuit. Such processing circuits include an electric circuit, a computer, a processor, a circuit board, a quantum circuit, or a semiconductor device. Each "unit" may use a common processing circuit (the same processing circuit), or may use different processing circuits (separate processing circuits). Input data or calculation results required for the reflection gradation value calculation unit 51, the recording processing unit 52, the determination unit 54, the recording processing unit 55, the determination unit 57, the shift processing unit 58, the extraction unit 65, the order determination unit 67, and the determination unit 68 are stored in a memory (not shown) in the lens array position control circuit 142 or in memory 111 each time.

[0153] FIG. 28 is a flowchart showing an example of some of the main steps of the inspection method according to the fourth embodiment. FIG. 29 is a flowchart showing an example of the remaining main steps of the inspection method according to the fourth embodiment. 28 and 29 are the same as those in FIG. 21 except that instead of the sorting process step (S130) and the order determination process (S132), an extraction process (S131), an order determination process (S133), a lens array shifting process (S140), an inspection process step (S200), a judgment process (S214), and a judgment process (S218) are performed.

[0154] As internal steps of the inspection processing step (S200), a series of steps including a scanning step (S202), a reference image creation step (S204), and a comparison step (S206) are carried out.

[0155] The contents of each of the inspection processing step (S100), mark scanning step (S108), reflection gradation value calculation step (S110), recording processing step (S112), judgment step (S114), recording processing step (S116), judgment step (S118), and lens array shifting step (S120) are the same as those in embodiment 3.

[0156] Therefore, in the determination step (S118), the steps from the inspection processing step (S100) to the lens array shift step (S120) are repeated until the k-th shift is completed.

[0157] As a result of the above, for each position of the shifted lens array 304, the gradation value of the ghost image (reflection gradation value) is recorded in the movement table in association with the arrangement position coordinates of the lens array 304.

[0158] In the extraction step (S131), the extraction unit 65 extracts the gradation values ​​equal to or less than the threshold value from among the gradation values ​​of the ghost image recorded for each position of the lens array 304 in the kth cycle.

[0159] FIG. 30 is a diagram showing an example of an extraction table in the fourth embodiment. In the extraction table, the reflection gradation value is defined so as to be associated with the x-value of the coordinate of the lens array 304 and the y-value of the coordinate of the lens array 304. For example, data in which the reflection gradation value is, for example, 5 or less as a threshold is extracted from the data recorded in the movement table such as that shown in FIG. 23. In the example of FIG. 30, for example, data in which the reflection gradation value is 3.2 and the coordinate of the lens array 304 is (478, 677) can be cited. For example, data in which the reflection gradation value is 1.1 and the coordinate of the lens array 304 is (246, 642) can be cited. For example, data in which the reflection gradation value is 3.3 and the coordinate of the lens array 304 is (654, ​​123) can be cited. For example, data in which the reflection gradation value is 1.3 and the coordinate of the lens array 304 is (299, 512) can be cited. For example, data with a reflection gradation value of 4.9 and coordinates of the lens array 304 of (333, 546) can be cited. Since no sorting process has been performed on the extraction table, the reflection gradation values ​​are not sorted in ascending order. Sorting may also be performed. The extraction table (extracted data) is stored in the storage device 66.

[0160] In the order determination step (S133), the order determination unit 67 determines the order of movement of each position of the lens array 304 to be next moved, giving priority to positions of the lens array 304 corresponding to smaller gradation values ​​of the ghost images recorded for each position of the lens array 304 in the kth cycle over positions of the lens array 304 corresponding to larger gradation values. Specifically, the order determination unit 67 determines the order of movement so that before movement to each position of the lens array 304 in the k+1th cycle, movement to a position of the lens array 304 corresponding to at least one extracted gradation value is performed, and then movement to each position of the lens array in the k+1th cycle is performed. Thus, here, the order of the k'th cycle is determined for some extracted positions to be shifted between the kth cycle and the k+1th cycle in the order listed in the extracted data.

[0161] In the lens array shifting step (S140), the shift processing unit 58 controls the stage control circuit 140 to shift the lens array 304 in the determined order for the k'th shift position. The stage control circuit 140 (control unit) controls the lens array stage 320 to shift the position of the lens array 304 to the next position under predetermined conditions. Here, for example, the position of the lens array 304 is shifted to the next position each time the elapsed time T reaches the threshold value Tth. The lens array 304 is shifted so that the focal points 12 of each divided light beam irradiate each position in the corresponding shift region 36 once in the order according to the extraction table. Next, the process proceeds to the inspection processing step (S200).

[0162] In the inspection process step (S200), the inspection device 100 performs an inspection process on a new substrate 101 with the lens array 304 shifted to a position along the extraction table.

[0163] In the scanning process (S202), the optical image acquisition mechanism 150 captures an image of the substrate 101 obtained by irradiating the substrate 101 on which a pattern is formed with inspection illumination light (first light) using the imaging sensor 105, and outputs the captured optical image data.

[0164] The image of the pattern formed on the image sensor 105 is photoelectrically converted by each photosensor element of the image sensor 105 and is further A / D (analog-to-digital) converted by a sensor circuit 106 .

[0165] The gradation value (image data) of each pixel is output to a stripe pattern memory 123.

[0166] Then, pixel value data of the inspection stripe 20 to be measured is stored in the stripe pattern memory 123. The measurement data (pixel data) is, for example, 8-bit unsigned data, and represents the brightness gradation (light amount) of each pixel. The pixel value data of the inspection stripe 20 is output to the comparison circuit 108. The contents of the scanning step (S102) are the same as those in the first embodiment.

[0167] In the reference image creation step (S204), the reference image creation circuit 112 creates a reference image to serve as a reference using graphic pattern data (design data). The creation of the reference image is performed for each inspection stripe 20 in parallel with the scanning step (S202) of that inspection stripe 20. The content of the reference image creation step (S104) is the same as in the first embodiment.

[0168] In the comparison step (S206), the comparison circuit 108 compares the frame image 31 (image to be inspected) using the image data with the reference image (predetermined image). The details of the comparison step (S206) are the same as those in the first embodiment.

[0169] When the inspection process for all the inspection stripes 20 that are the inspection areas of the target substrate 101 has been completed, the process proceeds to the determination step (S214).

[0170] In the determination step (S214), the determination unit 54 determines whether the elapsed time T from the time the lens array 304 was last shifted to the present has reached a threshold value Tth. The contents of the determination step (S214) are the same as those of the determination step (S114). If the elapsed time T from the time the lens array 304 was last shifted to the present has not reached the threshold value Tth, the process returns to the inspection process step (S200), and the inspection process step (S200) is repeated for each different substrate 101 until the elapsed time T reaches the threshold value Tth. If the elapsed time T has reached the threshold value Tth, the process proceeds to the determination step (S218).

[0171] In the determination step (S218), the determination unit 68 determines whether shifting has been performed to all positions defined in the extraction table. When shifting has been performed once to all positions defined in the extraction table, one cycle of each position defined in the extraction table has been completed. In other words, the determination unit 68 determines whether the k'th cycle of shifting has been completed. If the k'th cycle of shifting has been completed, the process proceeds to the lens array shifting step (S120). If the k'th cycle of shifting has not yet been completed, the process proceeds to the lens array shifting step (S140).

[0172] In the determination step (S218), the steps from the lens array shift step (S140) to the determination step (S218) are repeated until the k'th shift is completed.

[0173] As described above, the objective lens 104 is irradiated with each light at each position of the lens array 304 defined in the extraction table. In the fourth embodiment, by shifting the lens array 304 preferentially to positions where the gradation value (reflection gradation value) of the ghost image is small, the reflection intensity of the ghost image at each position can be made uniform or close to uniform, as shown in FIG. 26. As a result, the periodicity is eliminated, and the formation of a phase grating can be eliminated.

[0174] After the shift to each position where the gradation value (reflection gradation value) of the ghost image defined in the extraction table is small is completed, the process proceeds to the lens array shift step (S120) for the (k+1)th shift.

[0175] In the lens array shifting process (S120), the lens array 304 is shifted in a random order for the k+1th shift position, and the process returns to the inspection processing process (S100). In the judgment process (S118), each step from the inspection processing process (S100) to the lens array shifting process (S120) is repeated until the k+1th shift is completed.

[0176] As a result, for each position of the lens array 304 in the k+1th cycle, the gradation value of the ghost image (reflection gradation value) is recorded in the movement table in association with the arrangement position coordinates of the lens array 304. Thereafter, in the same manner, shifting is repeated for only some positions where the gradation value of the ghost image (reflection gradation value) defined in the extraction table is small during each cycle.

[0177] As described above, according to the fourth embodiment, even if ghost images are reflected, the periodicity of the phase grating can be eliminated, and the ghost images can be suppressed or reduced.

[0178] In the above description, the term "circuit" includes a processing circuit. Such processing circuits include, for example, an electric circuit, a computer, a processor, a circuit board, a quantum circuit, or a semiconductor device. Each "circuit" may use a common processing circuit (the same processing circuit), or may use different processing circuits (separate processing circuits). Furthermore, when a program is used, the program is recorded on a recording medium such as a magnetic disk device, a magnetic tape device, a FD, or a ROM (read-only memory).

[0179] Although the embodiments have been described above with reference to specific examples, the present invention is not limited to these specific examples.

[0180] In the above example, a case of reflection inspection using a reflective illumination optical system has been described, but the present invention is not limited to this. A phase grating can also be formed on the illumination lens when a transmission inspection is performed using a transmission illumination optical system. When a phase grating is formed on the illumination lens of a transmission illumination optical system, a ghost image can also be reflected in the image captured during transmission inspection, although the effect is smaller than that on the image captured during reflection inspection. Therefore, the above-described embodiments can also be applied when a transmission inspection is performed using a transmission illumination optical system. Therefore, the lens that irradiates the substrate 101 (mask substrate) with at least some of the multiple light beams split by the lens array 304 includes an objective lens and an illumination lens.

[0181] Furthermore, although descriptions of the device configuration, control method, and other parts not directly necessary for the explanation of the present invention have been omitted, the required device configuration and control method can be appropriately selected and used. For example, although the description of the control unit configuration that controls the inspection device 100 has been omitted, it goes without saying that the required control unit configuration can be appropriately selected and used.

[0182] In addition, all pattern inspection devices and pattern inspection methods that include the elements of the present invention and that can be appropriately modified by those skilled in the art are included within the scope of the present invention. [Explanation of symbols]

[0183] 10 Inspection Area 11 Mark Pattern 12 Focusing point 13 Pattern formation area 20 Inspection Stripes 30 Frame Area 31 Relay Lens 32 Beam Splitter 34 Focus point 36 Shift Area 50, 53,56,60,66 storage device 51 Reflection gradation value calculation unit 52 Recording processing section 54 Judgment section 55 Recording processing section 57 Judgment section 58 Shift processing section 59 Sorting processing section 61 Order determining part 65 Extraction part 66 Storage device 67 Order determining part 68 Judgment section 70,72,76 storage device 74 Frame image creation section 78 Alignment section 79 Comparison processing section 100 Inspection equipment 101 Mask substrate 102 XYθ table 103 Light source 104 Objective Lens 105 Image Sensor 106 Sensor Circuit 107 Position circuit 108 Comparison circuit 109 Magnetic disk unit 110 Control computer 111 memory 112 Reference image creation circuit 114 Table control circuit 115 Drive mechanism 120 Bus 123 Stripe Pattern Memory 140 Stage control circuit 150 Optical image acquisition mechanism 160 Control Circuits 176 Beam Splitter 178 Imaging Optical System 270 Reflected illumination optical system 271 Lens 300 Kohler illumination optical system 302 Beam Expander 304 Lens Array 308 Collimator Lens 310 Lighting slit 320 Lens Array Stage 322 Drive Mechanism 324 Light Sensor 501 Laser light 502 Beam Expander 504 Lens Array 505 relay lens 506 Objective Lens 508 Mask substrate 510 Imaging Lens 512 Image Sensor

Claims

1. First and second lens arrays, each having a different lens arrangement pitch, receive an inspection light and split the inspection light into a plurality of light beams; a stage that supports the first and second lens arrays and is movable within a plane perpendicular to the optical axis of the inspection light; a lens that irradiates a mask substrate on which a graphic pattern is formed with at least some of the light beams split by one of the first and second lens arrays; an imaging sensor that captures an optical image of the mask substrate by illuminating the mask substrate; a light intensity sensor for measuring the intensity of the inspection light; a control unit that controls the stage so as to switch the lens array irradiated with the inspection light from one of the first and second lens arrays to the other when the measured integrated light amount becomes equal to or greater than a threshold value; A mask inspection apparatus comprising:

2. a lens array that receives the inspection light and splits the inspection light into a plurality of beams; a stage that supports the lens array and is movable within a plane perpendicular to the optical axis of the inspection light; a lens for irradiating a mask substrate on which a graphic pattern is formed with at least some of the plurality of light beams; an imaging sensor that captures an optical image of the mask substrate by illuminating the mask substrate; a control unit that controls the stage to shift the position of the lens array under a predetermined condition; a recording processing unit that records a gradation value at a predetermined position of the image of the figure pattern using the captured optical image for each position of the lens array; an order determination unit that determines the order in which the lens array is moved next, giving priority to positions of the lens array corresponding to smaller gradation values ​​than positions of the lens array corresponding to larger gradation values ​​among the gradation values ​​recorded for each position of the lens array in the kth cycle; A mask inspection apparatus comprising:

3. a sorting processing unit that sorts the gradation values ​​recorded for each position of the lens array in the kth iteration in ascending order, 3. The mask inspection apparatus according to claim 2, wherein the order determination unit determines the order of movement of each position of the lens array in the (k+1)th turn in ascending order of gradation value.

4. an extracting unit that extracts gradation values ​​equal to or less than a threshold value from among the gradation values ​​recorded for each position of the lens array for the kth cycle; 3. The mask inspection apparatus according to claim 2, wherein the order determination unit determines the movement order so that, before the lens array moves to each position in the (k+1)th cycle, the lens array moves to a position corresponding to at least one extracted gradation value, and then the lens array moves to each position in the (k+1)th cycle.

5. 5. The mask inspection apparatus according to claim 1, wherein the lens for illuminating the mask substrate is either an objective lens or an illumination lens.

6. receiving inspection light irradiated onto a first lens array and dividing the inspection light into a plurality of light beams by the lens array; irradiating a mask substrate having a graphic pattern formed thereon with at least some of the plurality of light beams using a lens; capturing an optical image of the mask substrate using an imaging sensor, the optical image being obtained by illuminating the mask substrate; comparing the captured optical image of the mask substrate with a predetermined image and outputting the result; measuring the amount of the inspection light using a light amount sensor; when the measured integrated light amount is equal to or greater than a threshold, switching the lens array irradiated with the inspection light from the first lens array to a second lens array having lenses arranged at a different pitch from that of the first lens array; A mask inspection method comprising:

7. shifting the position of the lens array under predetermined conditions; a step of irradiating the lens array with inspection light for each position of the lens array and dividing the inspection light into a plurality of light beams by the lens array; a step of irradiating a corresponding mask substrate among a plurality of mask substrates on which graphic patterns are formed with at least some of the plurality of lights using a lens at each position of the lens array; capturing an optical image of the corresponding mask substrate using an imaging sensor at each position of the lens array by illuminating the corresponding mask substrate; For each position of the lens array, comparing the captured optical image of the corresponding mask substrate with a predetermined image and outputting the result; a step of recording a gradation value at a predetermined position with respect to an image of the graphic pattern using an optical image captured for each position of the lens array; determining a movement order of the positions of the lens array to be moved next by prioritizing the positions of the lens array corresponding to smaller gradation values ​​among the gradation values ​​recorded for each position of the lens array in the kth cycle over the positions of the lens array corresponding to larger gradation values; A mask inspection method comprising:

Images