Pattern inspection device and pattern inspection method

Abstract

The invention provides a pattern inspection device and a pattern inspection method, which can focus the focal point of the light beam of each detection optical system on each imaging sensor even when a plurality of inspection images are simultaneously captured by different imaging sensors. A pattern inspection device according to one embodiment of the present invention is provided with: a first detection means for detecting a change in a first positional relationship between a focal position of a first light beam and a first sensor; a second detection mechanism that detects a change in a second positional relationship between the focal position of the second light beam and the second sensor; a third detection mechanism that detects a change in a third positional relationship between the focal position of the separated third light beam and the focal position on the substrate side of the common detection optical system; the control circuit controls at least two of the first adjusting mechanism, the second adjusting mechanism and the third adjusting mechanism so as to adjust at least two of the first position relation, the second position relation and the third position relation.

Description

[0001] This application claims priority to Japanese Patent Application No. 2024-135118 (Filing Date: August 13, 2024). The entire contents of the base application are incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to a pattern inspection apparatus and a pattern inspection method. For example, it relates to an apparatus for inspecting a pattern defect of an exposure mask used for semiconductor manufacturing and a focus position adjustment method of the apparatus. BACKGROUND

[0003] In recent years, with high integration and large capacity of large scale integrated circuits (LSIs), circuit line widths required for semiconductor elements are becoming narrower. These semiconductor elements are manufactured by forming a circuit by exposing and transferring a pattern onto a wafer using a so-called reduction projection exposure apparatus called a stepper, using a reticle pattern (also called a mask or an intermediate mask, hereinafter collectively referred to as a mask) on which a circuit pattern is formed.

[0004] Furthermore, for the manufacturing of LSIs which cost a large amount of manufacturing cost, improvement of yield is indispensable. As one of the main reasons for lowering the yield, a pattern defect of a mask used when exposing and transferring a super-fine pattern on a semiconductor wafer using a lithography technique can be cited. In recent years, with miniaturization of the size of an LSI pattern formed on a semiconductor wafer, the size to be detected as a pattern defect has become extremely small. Therefore, high precision of a pattern inspection apparatus for inspecting a defect of a transfer mask used for LSI manufacturing is required.

[0005] As an inspection method, for example, there are "die to die inspection" in which optical image data obtained by photographing the same pattern on different places on the same mask are compared with each other, and "die to database inspection" in which CAD data of a pattern design is converted into drawing data (design data) in a device input format inputted to a drawing device when a pattern is drawn on a mask, and a reference image is generated based on this, and an optical image of measurement data obtained by photographing a pattern is compared.

[0006] In the inspection apparatus, it is necessary to clearly capture an image of a pattern on a mask as an inspection object. However, since there is a limited depth of focus in the optical system of the inspection apparatus, it is necessary to continuously hold the inspection surface of the inspection object within the depth of focus of the optical system in the inspection. In other words, it is required to hold the contrast of the captured image within an allowable range. In the inspection apparatus, it is necessary to continuously capture images while scanning the mask by moving a stage, and it is not realistic to calculate the image contrast one by one in the inspection to adjust the focus of the optical system due to insufficient processing time.

[0007] Therefore, in the inspection apparatus, in addition to the inspection optical system for image capturing, an autofocus mechanism that detects displacement of the inspection object in the height direction with respect to the inspection optical system and adjusts the height position is employed.

[0008] With recent miniaturization of patterns, shortening of the wavelength of inspection light is progressing. Along with this, the depth of focus of the inspection optical system is becoming shallower. Therefore, the precision of the measurement system of the independent autofocus mechanism that was conventionally provided in the vicinity of the inspection optical system was sufficient, but without performing in-situ measurement using the inspection optical system itself, it was not possible to detect various fluctuation factors (temperature / mechanical deformation dependency) possessed by the inspection optical system, and high-precision focus adjustment was not possible. Therefore, as the autofocus mechanism, a method of utilizing a part of the inspection optical system was employed (for example, refer to Japanese Patent Application Publication No. 2020-125941).

[0009] For example, the height position of the mask is measured by measuring the light amount passing through a slit disposed before and after the focus position of the image from the mask, calculating the difference between the two measured light amounts, and thereby performing autofocus. In the optical system of this autofocus mechanism, it is ideal to adjust in such a manner that the focus of the detection optical system that captures the inspection image is aligned with the imaging sensor in a state where the focus adjustment is performed in such a manner that the difference between the two light amounts becomes zero. However, in a case where different imaging sensors are used to simultaneously capture different regions on the mask, the focus position of one detection optical system and the focus position of the other detection optical system do not necessarily coincide. Therefore, if they coincide with one, there is a problem that the other deviates. SUMMARY

[0010] One aspect of the present application provides a pattern inspection apparatus and a pattern inspection method that can focus the focus of the light beam of each detection optical system on each imaging sensor even in a case where a plurality of inspection images are simultaneously captured using different imaging sensors.

[0011] The pattern inspection apparatus of one aspect of the present application includes:

[0012] A stage on which a substrate on which a pattern is formed is placed;

[0013] A first sensor that captures a first optical image of the substrate by receiving a first light beam transmitted or reflected at a first region of the substrate;

[0014] A second sensor that captures a second optical image of the substrate by receiving a second light beam transmitted or reflected at a second region of the substrate at the same timing as the receiving timing of the first sensor;

[0015] A common detection optical system that illuminates a third region of the substrate with light for focus adjustment and guides the first light beam, the second light beam, and a third light beam reflected at the third region of the substrate onto a common detection optical path;

[0016] A light beam separation mechanism that separates the first light beam, the second light beam, and the third light beam;

[0017] A first detection optical system that images the separated first light beam on the first sensor;

[0018] A second detection optical system that images the separated second light beam on the second sensor;

[0019] A first detection mechanism that detects a change in a first positional relationship between a focal point position of the first light beam and the first sensor;

[0020] A second detection mechanism that detects a change in a second positional relationship between a focal point position of the second light beam and the second sensor;

[0021] A third detection mechanism that detects a change in a third positional relationship between a focal point position of the separated third light beam and a focal point position of the common detection optical system on the substrate side;

[0022] A first adjustment mechanism that automatically adjusts the first positional relationship;

[0023] A second adjustment mechanism that automatically adjusts the second positional relationship;

[0024] A third adjustment mechanism that automatically adjusts the third positional relationship; and

[0025] A control circuit that controls at least two of the first adjustment mechanism, the second adjustment mechanism, and the third adjustment mechanism based on the change in the first positional relationship, the change in the second positional relationship, and the change in the third positional relationship to adjust at least two of the first positional relationship, the second positional relationship, and the third positional relationship.

[0026] A pattern inspection method according to one aspect of the present invention is,

[0027] using the first sensor, receiving a first light beam transmitted or reflected at a first region of a substrate on which a patterned pattern is formed, placed on a stage, thereby capturing a first optical image of the substrate,

[0028] using the second sensor, receiving a second light beam transmitted or reflected at a second region of the substrate at the same timing as the receiving timing of the first sensor, thereby capturing a second optical image of the substrate,

[0029] using a common detection optical system, illuminating a third region of the substrate with light for focus adjustment, and guiding the first light beam, the second light beam, and a third light beam reflected at the third region of the substrate onto a common detection optical path,

[0030] separating the first light beam, the second light beam, and the third light beam,

[0031] using the first detection optical system, imaging the separated first light beam on the first sensor,

[0032] using the second detection optical system, imaging the separated second light beam on the second sensor,

[0033] detecting a change in a first positional relationship between a focal position of the first light beam and the first sensor,

[0034] detecting a change in a second positional relationship between a focal position of the second light beam and the second sensor,

[0035] detecting a change in a third positional relationship between a focal position of the separated third light beam and a focal position of the substrate side of the common detection optical system,

[0036] based on the change in the first positional relationship, the change in the second positional relationship, and the change in the third positional relationship, controlling at least two of a first adjustment mechanism that automatically adjusts the first positional relationship, a second adjustment mechanism that automatically adjusts the second positional relationship, and a third adjustment mechanism that automatically adjusts the third positional relationship, to adjust at least two of the first positional relationship, the second positional relationship, and the third positional relationship. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a structural diagram showing an example of the structure of the pattern inspection apparatus in Embodiment 1.

[0038] Figure 2 is a structural diagram showing an example of the structure of the reflection illumination optical system and an example of the detection optical system in Embodiment 1.

[0039] Figure 3 is a conceptual diagram for explaining the inspection region in Embodiment 1.

[0040] Figure 4is a diagram showing an example of each region in the substrate surface in Embodiment 1.

[0041] Figure 5 is a plan view of another example of the light beam separating mechanism in Embodiment 1.

[0042] Figure 6 is a sectional view of another example of the light beam separating mechanism in Embodiment 1.

[0043] Figure 7 is a diagram showing an example of the structure of the imaging sensor in Embodiment 1.

[0044] Figure 8 is a diagram for explaining an example of a method of focus detection using a part of the imaging sensor in Embodiment 1.

[0045] Figure 9 is a diagram showing another example of the structure of the imaging sensor in Embodiment 1.

[0046] Figure 10 is a block diagram showing an example of the internal structure of the auto focus control circuit in Embodiment 1.

[0047] Figure 11 is a flowchart showing an example of the main part of the procedure of the inspection method in Embodiment 1.

[0048] Figure 12 is a diagram for explaining the filter processing in Embodiment 1.

[0049] Figure 13 is a diagram showing an example of the internal structure of the comparison circuit in Embodiment 1.

[0050] Figure 14 is a structure diagram showing an example of the structure of the pattern inspection apparatus in Embodiment 2.

[0051] Figure 15 is a structure diagram showing an example of the structure of the reflection illumination optical system and an example of the detection optical system in Embodiment 2. DETAILED DESCRIPTION

[0052] Embodiment 1

[0053] Figure 1 is a structure diagram showing an example of the structure of the pattern inspection apparatus in Embodiment 1.

[0054] Figure 2 is a structure diagram showing an example of the structure of the reflection illumination optical system and an example of the detection optical system in Embodiment 1.

[0055] In Figure 1 andFigure 2 In the present embodiment, an inspection apparatus 100 that inspects a defect of a pattern formed on an inspection target substrate, such as a mask, is provided with an optical image acquisition mechanism 150 and a control system circuit 160.

[0056] The optical image acquisition mechanism 150 has a light source 103, a transmission illumination optical system 170, a reflection illumination optical system 171, a movably arranged XYθ stage 102, a shared detection optical system 172, a split mirror 177 (fixed mirror: an example of a beam splitting mechanism), a detection optical system 176, a detection optical system 276, an autofocusing mechanism 131, an imaging sensor 105, a sensor circuit 106, a strip pattern memory 123, an imaging sensor 205, a sensor circuit 206, a strip pattern memory 223, a laser length measuring system 122, and an automatic loader 130.

[0057] The shared detection optical system 172 includes a magnification optical system 104, a beam splitter 174, and an imaging lens 175.

[0058] The detection optical system 176 includes a collimator lens 178, an imaging lens 179, and a driving mechanism 135.

[0059] The detection optical system 276 includes a collimator lens 278, an imaging lens 279, and a driving mechanism 235.

[0060] The autofocusing mechanism 131 includes an autofocusing optical system 180, a light quantity sensor 185 (first light quantity sensor), a light quantity sensor 187 (second light quantity sensor), a Z driving mechanism 132, and a position sensor 134. A confocal sensor is configured by the autofocusing optical system 180, the light quantity sensor 185, the light quantity sensor 187, and an autofocusing control circuit 140.

[0061] The autofocusing optical system 180 includes an imaging optical system 181, a beam splitter 182, a slit plate 184, and a slit plate 186. The autofocusing optical system 180 guides light (third light beam) reflected in an autofocusing (AF) field region (third region) of the inspected substrate 101 to the light quantity sensor 185 and the light quantity sensor 187. The beam splitter 182 is arranged immediately before a focal position. The slit plate 184 is arranged at a front focal position (front-side focal position) and receives light transmitted through the beam splitter 182. The light quantity sensor 185 measures the light quantity of light that has passed through the slit plate 184 arranged at the front focal position (front-side focal position). The slit plate 186 is arranged at a rear focal position (rear-side focal position) and receives light split by the beam splitter 182. The light quantity sensor 187 measures the light quantity of light that has passed through the slit plate 186 arranged at the rear focal position (rear-side focal position).

[0062] The position sensor 134 measures the height position of the pattern formation surface of the substrate 101. For example, the height position of the surface of the glass substrate is measured.

[0063] The substrate 101 to be inspected, which is carried from the automatic loader 130, is arranged on the XYθ stage 102 (stage). As the substrate 101 to be inspected, for example, a photomask for exposure that transfers a pattern to a semiconductor substrate such as a wafer is included. Further, a pattern to be inspected is formed on the photomask. The substrate 101 is placed on the XYθ stage 102 with the pattern formation surface facing the lower side, for example. The stage is an example of the stage of the XYθ stage 102.

[0064] As the imaging sensor 105, a line sensor or a two-dimensional sensor is used. For example, a TDI (Time Delay Integration) sensor is preferably used. The TDI sensor has a plurality of photo sensor elements (detection elements) arranged in two dimensions. When each photo sensor element photographs an image, a predetermined image accumulation time is set. In the TDI sensor, the outputs of the plurality of photo sensor elements arranged in the scanning direction are integrated and output. The plurality of photo sensor elements arranged in the scanning direction photograph the same pixel while shifting the time according to the movement of the XYθ stage 102. In the case of using the line sensor, the plurality of photo sensor elements are arranged in a direction orthogonal to the scanning direction.

[0065] In the control system circuit 160, the control computer 110 that controls the entire inspection apparatus 100 is connected to the position circuit 107, the plurality of comparison circuits 108, the reference image creation circuit 112, the automatic loader control circuit 113, the stage control circuit 114, the autofocus control circuit 140, the disk device 109, the memory 111, the floppy disk device (FD) 115, the tape device 116, the CRT 117, the pattern monitor 118, and the printer 119 via the bus 120. Further, the imaging sensor 105 is connected to the strip pattern memory 123, and the strip pattern memory 123 is connected to the comparison circuit 108a in the plurality of comparison circuits 108, for example. The imaging sensor 205 is connected to the strip pattern memory 223, and the strip pattern memory 223 is connected to the comparison circuit 108b in the plurality of comparison circuits 108, for example. Further, the reference image creation circuit 112 is connected to the plurality of comparison circuits 108.

[0066] The output of the position sensor 134 is connected to the autofocus control circuit 140. Further, the outputs of the light quantity sensors 185, 187 are connected to the autofocus control circuit 140.

[0067] In addition, the series of "circuit" such as the position circuit 107, the plurality of comparison circuits 108, the reference image creation circuit 112, the auto loader control circuit 113, the stage control circuit 114, and the auto focus control circuit 140 has a processing circuit. The processing circuit includes an electric circuit, a computer, a processor, a circuit board, a quantum circuit, or a semiconductor device, and the like. Each circuit can be configured using the same processing circuit (one processing circuit) or using different processing circuits (separate processing circuits). For example, the series of "circuit" such as the position circuit 107, the plurality of comparison circuits 108, the reference image creation circuit 112, the auto loader control circuit 113, the stage control circuit 114, and the auto focus control circuit 140 can also be configured by the control computer 110 and executed. The input data required for the position circuit 107, the plurality of comparison circuits 108, the reference image creation circuit 112, the auto loader control circuit 113, the stage control circuit 114, and the auto focus control circuit 140 or the result of the operation is stored in a memory or the memory 111 not shown in each circuit each time. The input data required for the control computer 110 or the result of the operation is stored in a memory or the memory 111 not shown in the control computer 110 each time. A program executed by the processor or the like can be recorded in the disk device 109, the FD 115, the tape device 116, or a recording medium such as a ROM (Read Only Memory).

[0068] In the inspection device 100, as an inspection optical system, a reflection inspection optical system and / or a transmission inspection optical system are mounted. The reflection inspection optical system of high magnification is configured by the light source 103, the reflection illumination optical system 171, the beam splitter 174, the magnification optical system 104, the XYθ stage 102, the imaging lens 175, the collimator lens 178, and the imaging lens 179.

[0069] In addition, the transmission inspection optical system of high magnification is configured by the light source 103, the transmission illumination optical system 170, the XYθ stage 102, the magnification optical system 104, the beam splitter 174, the imaging lens 175, the collimator lens 278, and the imaging lens 279.

[0070] In addition, the XYθ stage 102 is driven by the stage control circuit 114 under the control of the control computer 110. It is possible to move by a drive system such as a 3-axis (X-Y-θ) motor driven in the X direction, the Y direction, and the θ direction. These X-axis motor, Y-axis motor, and θ-axis motor can use, for example, a stepping motor. The XYθ stage 102 is able to move in the horizontal direction and the rotational direction by the motors of the respective axes of the XYθ. The XYθ stage 102 is an example of a stage. Furthermore, the moving position of the substrate 101 disposed on the XYθ stage 102 is measured by the laser length measuring system 122, and is supplied to the position circuit 107. In addition, the conveyance processing of the substrate 101 from the automatic loader 130 to the XYθ stage 102 and the conveyance processing of the substrate 101 from the XYθ stage 102 to the automatic loader 130 are controlled by the automatic loader control circuit 113.

[0071] In addition, the XYθ stage 102 is driven in the z direction by the Z drive mechanism 132 controlled by the autofocus control circuit 140. As the Z drive mechanism 132, for example, a piezoelectric element or a stepping motor is preferably used. In addition, the height position of the XYθ stage 102 is measured by the position sensor 134, and the measurement result is output to the autofocus control circuit 140. In Figure 1 and Figure 2 In the example of the above, the case where the Z drive mechanism 132 moves the XYθ stage 102 is shown, but is not limited thereto. The Z drive mechanism 132 can also move, for example, the magnification optical system 104 (objective lens) in the z direction.

[0072] Furthermore, the collimator lens 178 is driven in the optical axis direction by the drive circuit 135 controlled by the autofocus control circuit 140. As the drive circuit 135, for example, a piezoelectric element or a stepping motor is preferably used. In Figure 1 and Figure 2 In the example of the above, the case where the drive mechanism 135 moves the collimator lens 178 is shown, but is not limited thereto. For example, the drive circuit 135 can drive the imaging lens 179 or the imaging sensor 105 in the optical axis direction.

[0073] Likewise, the collimator lens 278 is driven in the optical axis direction by the drive circuit 235 controlled by the autofocus control circuit 140. As the drive circuit 235, for example, a piezoelectric element or a stepping motor is preferably used. In Figure 1 and Figure 2 In the example of the above, the case where the drive mechanism 235 moves the collimator lens 278 is shown, but is not limited thereto. For example, the drive circuit 235 can drive the imaging lens 279 or the imaging sensor 205 in the optical axis direction.

[0074] The drawing data (design data) that forms the basis for the pattern formation of the substrate 101 under inspection is input from outside the inspection device 100 and stored in the disk device 109. Multiple graphic patterns are defined in the drawing data, each typically consisting of a combination of multiple element graphics. Alternatively, a graphic pattern consisting of a single graphic may also be used. On the substrate 101 under inspection, corresponding patterns are formed based on the graphic patterns defined in the drawing data.

[0075] The light generated from light source 103 is separated into light for transmission inspection and light for reflection inspection by an optical element (not shown). Figure 2 The image shows an example of the structure of a reflective illumination optical system 171 for incident reflection inspection of light 11.

[0076] The reflective illumination optical system 171 includes a half-wave plate 40, a Rosen prism 42, a collimating lens 44, a half-wave plate 49, a half-wave plate 45, a slit plate 46-1, and a lens 43.

[0077] exist Figure 2 In the example, the polarization direction (electric field vibration direction) of the light 11 incident on the reflective illumination optical system 171 is adjusted to a certain direction by an optical element not shown. For example, light 11 (P-wave) with a polarization direction of 90 degrees from the x-axis is incident on the reflective illumination optical system 171 relative to a plane (xz plane) orthogonal to the direction of travel of the light 11.

[0078] The polarization direction of the light 11 (first light) incident on the half-wave plate 40 is changed by adjusting the angle of the half-wave plate 40. At this time, as... Figure 2 As shown, the angle is adjusted to accommodate a higher proportion of P-wave components, used as the inspection light, and a lower proportion of S-wave components, used as the measurement light for autofocus. Light 12, containing both P-wave and S-wave components, output from the half-wave plate 40, is incident on the Rosen prism 42, separating the tracks of the P-wave and S-wave components. For example, the P-wave component is output directly, while the S-wave component is output at an angle. This separates the light into an inspection light 14 and a measurement light 16. Both the inspection light 14 and the measurement light 16 are incident on the collimating lens 44 and refracted to form parallel tracks. For example, the inspection light 14 passes through the center of the collimating lens 44 and is output in a straight direction. The measurement light 16 passes through the outer periphery of the collimating lens 44, is refracted in the focusing direction, and is output in a direction parallel to the inspection light 14.

[0079] The inspection light 14 that has passed through the collimator lens 44 becomes a polarization direction of, for example, a P wave, and the measurement light 16 that has passed through the collimator lens 44 becomes a polarization direction of, for example, an S wave. Therefore, the measurement light 16 is incident on the 1 / 2 wavelength plate 49, is converted into light (for example, a P wave) of the same polarization direction as the inspection light 14, and is output. Both the inspection light 14 and the measurement light 16 are incident on the slit plate 46-1 in parallel after being converted into, for example, S waves and being output.

[0080] A slit opening portion 47 of, for example, a rectangular shape for forming a reflection field of view for reflection inspection is formed in the slit plate 46-1. In addition, a slit opening portion 48 that limits passage of measurement light (light for auto-focusing) for measuring a height position deviation of the substrate 101 from a focal height is formed in the slit plate 46-1. As the slit opening portion 48, for example, a cross-shaped opening portion is preferably used. The inspection light 14 is irradiated in a manner that includes the entire slit opening portion 47. Likewise, the measurement light 16 is irradiated in a manner that includes the entire slit opening portion 48. The inspection light 14 of the reflection field of view slit image that has passed through the slit opening portion 47 is incident on the beam splitter 174 via the lens 43 in a state of, for example, a polarization direction of an S wave. Likewise, the measurement light 16 of the focus slit image (F slit image) that has passed through the slit opening portion 48 is incident on the beam splitter 174 via the lens 43 in a state of, for example, a polarization direction of an S wave.

[0081] The reflection illumination optical system 171 illuminates an auto-focusing illumination field region (third region) of the substrate 101 with the measurement light 16 that has passed through the slit plate 46-1. The reflection illumination optical system 171 also illuminates a reflection illumination field region (an example of the first region) of the substrate 101 with the inspection light 14. Specifically, the inspection light 14 and the measurement light 16 that are incident on the beam splitter 174 are reflected by the beam splitter 174 and are irradiated onto the substrate 101 by the magnification optical system 104. In other words, the common detection optical system 172 illuminates a focus field region of the substrate 101 under inspection with the measurement light 16 for focus adjustment.

[0082] Since the inspection light 14 and the measurement light 16 are imaged with the same lens, the focal height position of the inspection light 14 is the same as the focal height position of the measurement light 16. In this way, in the reflection inspection, the beam splitter 174 and the magnification optical system 104 function as a part of the reflection illumination optical system 171.

[0083] On the other hand, in the transmission illumination optical system 170, also similarly, the inspection light 15 of the same polarization direction (electric field vibration direction), for example, is irradiated in a manner of containing the entire slit opening portion of a rectangle, for example, not illustrated, which forms a transmission field of view for transmission inspection, and the transmission illumination field region (an example of the second region) of the substrate 101 is illuminated with the inspection light 15 of the transmission field of view slit image passing through the slit opening portion.

[0084] The light beam 19-1 (first light beam) reflected by the reflection illumination field region (an example of the first region) of the substrate 101, the light beam 19-2 (second light beam) transmitted through the transmission illumination field region (an example of the second region) of the substrate 101, and the light beam 19-3 (third light beam) reflected by the autofocus illumination field region (an example of the third region) of the substrate 101 are all guided onto the common detection light path by the common detection optical system 172. Specifically, the light beam 19-1 reflected by the reflection illumination field region of the substrate 101, the light beam 19-2 transmitted through the transmission illumination field region of the substrate 101, and the light beam 19-3 reflected by the autofocus illumination field region of the substrate 101 all pass through the magnification optical system 104, the beam splitter 174, and the imaging lens 175 as the common detection optical system 172, and travel to the separation mirror 177. The imaging lens 175 images the three light beams 19-1, 19-2, and 19-3 on the reflection surface of the separation mirror 177.

[0085] The separation mirror 177 (an example of a light beam separation mechanism) has, for example, two reflection surfaces facing different directions, for example, with a gap formed between the reflection surfaces. Each reflection surface reflects a predetermined light beam and causes the predetermined light beam to pass through the gap. Thus, the separation mirror 177 (an example of a light beam separation mechanism) separates the light beam 19-1 reflected in the reflection illumination field region of the substrate 101, the light beam 19-2 transmitted through the transmission illumination field region of the substrate 101, and the light beam 19-3 reflected in the autofocus illumination field region of the substrate 101. Specifically, the light beam 19-1 reflected in the reflection illumination field region of the substrate 101, for example, enters the detection optical system 176 by the separation mirror 177. The light beam 19-2 transmitted through the transmission illumination field region of the substrate 101, for example, is reflected by the separation mirror 177 and enters the detection optical system 276. The light beam 19-3 reflected in the autofocus illumination field region of the substrate 101 is reflected by the separation mirror 177 and enters the autofocus optical system 180.

[0086] The light flux 19-1 which is split and incident to the detection optical system 176 is imaged on the imaging sensor 105 (first sensor) by the detection optical system 176 (first detection optical system). Specifically, the light flux 19-1 which is incident to the detection optical system 176 is refracted by the collimator lens 178 to become parallel light and enters the imaging lens 179 while expanding in the diverging direction. Then, the imaging lens 179 refracts the light flux 19-1 in the converging direction and images on the detection surface of the imaging sensor 105. The imaging sensor 105 captures an optical image (first optical image) of the inspected substrate 101 by receiving the light flux 19-1 which is reflected by, for example, the reflected illumination field region (first region) of the inspected substrate 101 (or also the light flux which is transmitted through the transmitted illumination field region).

[0087] The light flux 19-2 which is split and incident to the detection optical system 276 is imaged on the imaging sensor 205 (second sensor) by the detection optical system 276 (second detection optical system). Specifically, the light flux 19-2 which is incident to the detection optical system 276 is refracted by the collimator lens 278 to become parallel light and enters the imaging lens 279 while expanding in the diverging direction. Then, the imaging lens 279 refracts the light flux 19-2 in the converging direction and images on the detection surface of the imaging sensor 205. The imaging sensor 205 captures an optical image (second optical image) of the inspected substrate 101 by receiving the light flux 19-2 which is transmitted through, for example, the transmitted illumination field region (second region) of the inspected substrate 101 (or also the light flux which is reflected by the reflected illumination field region) at the same timing as the reception timing of the imaging sensor 105.

[0088] The light flux 19-3 which is incident to the auto focus optical system 180 is refracted in the converging direction by the imaging optical system 181 and irradiates the beam splitter 182. A part of the light which is transmitted through the beam splitter 182 is limited by the slit plate 184 of the front focal position (front focal position) and the light quantity of the light which passes through the slit plate 184 is measured by the light quantity sensor 185. A part of the light which is branched by the beam splitter 182 is limited by the slit plate 186 of the rear focal position (rear focal position) and the light quantity of the light which passes through the slit plate 186 is measured by the light quantity sensor 187. Thus, the light quantity at the front focal position and the light quantity at the rear focal position can be measured. The respective light quantity data (light intensity data) of the light quantity at the front focal position and the light quantity at the rear focal position which are measured in the scanning are output to the auto focus control circuit 140.

[0089] Here, in Figure 1 and Figure 2 , the constituent parts required for the embodiment 1 are described. For the inspection apparatus 100, of course, other structures which are necessary can also be included as usual.

[0090] Figure 3 is a conceptual diagram for explaining the inspection area in Embodiment 1. As shown in Figure 3 , the inspection area 10 (the entire inspection area) of the substrate 101 is virtually divided into a plurality of inspection strips 20 in a long strip shape of the scan width W of the imaging sensor 105 (205), for example, in the Y direction.

[0091] In addition, as will be described later, in Embodiment 1, instead of imaging for inspection images, a group of a part of the plurality of detection elements of the imaging sensor 105 (205) is used for focus detection of the optical system 176 (276). Therefore, the scan width W here refers to the width of the detection element column that captures the inspection image other than the detection element column for focus detection.

[0092] Further, in the inspection apparatus 100, an image (strip area image) is acquired for each inspection strip 20. For each inspection strip 20, an image of a patterned pattern arranged in the inspection strip 20 is captured in the long side direction (X direction) of the strip area using laser light (inspection light). In addition, in order to prevent omission of the image, the plurality of inspection strips 20 are preferably set so that adjacent inspection strips 20 overlap each other by a prescribed margin width.

[0093] By the movement of the XYθ stage 102, the imaging sensor 105 continuously moves in the X direction while capturing the optical image. The imaging sensor 105 (205) continuously captures the optical image in the scan width W as shown in Figure 3 . In Embodiment 1, after the optical image in one inspection strip 20 is captured, the position of the next inspection strip 20 is moved in the Y direction, and the optical image in the scan width W is continuously captured in the same manner while moving in the opposite direction. That is, the capturing is repeated in the forward (FWD) -backward (BWD) direction toward the opposite direction in the forward and backward directions.

[0094] In addition, at the time of actual inspection, as shown in Figure 3 , the strip area image of each inspection strip 20 is divided into images (frame images 31) of a plurality of frame areas 30 in a rectangular shape. Then, each frame image 31 of the frame area 30 is subjected to inspection. For example, the division is in a size of 512 x 512 pixels. Therefore, a reference image for comparison with the frame image 31 of the frame area 30 is also made for each frame area 30 in the same manner.

[0095] Here, the direction of imaging is not limited to the repetition of the forward (FWD) -backward (BWD). The capturing can also be performed from one direction. For example, it can also be FWD-FWD repetition. Or, it can also be BWD-BWD repetition.

[0096] Figure 4 is a diagram showing an example of each region in the substrate surface in Embodiment 1. In Figure 4 , an example of each irradiation position in the case of scanning the k-th inspection strip 20 is shown. In Figure 4 , in the case of performing scanning of each inspection strip 20, with respect to the inspection strip 20 of the object, the transmission field of view (slit image) of the inspection light 15 for transmission inspection is irradiated to the transmission illumination field of view region (an example of the second region) of the substrate 101, and the reflection field of view (slit image) of the inspection light 14 for reflection inspection is irradiated to the reflection illumination field of view region (an example of the first region). Further, the autofocus (AF) image of the measurement light is irradiated to the autofocus (AF) illumination field of view region (an example of the third region) of the substrate 101. The transmission illumination field of view region and the reflection illumination field of view region of the substrate 101 are configured in a manner arranged in the scanning direction. In addition, the AF field of view region is disposed in the vicinity of, for example, the front in the scanning direction with respect to each inspection field of view. The transmission illumination field of view region, the reflection illumination field of view region, and the AF field of view region change their positions in time as the scanning operation based on the movement of the XYθ stage 102 is performed, in a state of maintaining the relative positional relationship.

[0097] Figure 5 is a plan view of another example of the beam splitting mechanism in Embodiment 1.

[0098] Figure 6 is a cross-sectional view of another example of the beam splitting mechanism in Embodiment 1.

[0099] In the example of Figure 1 , a case using a fixed split mirror 177 is explained as an example of the beam splitting mechanism, but is not limited thereto. In Figure 5 and Figure 6In the present embodiment, as another example of the light beam separating mechanism, a time division mirror mechanism 173 is shown. The time division mirror mechanism 173 has two time division mirrors 90-1, 90-2 in a disc shape and three slit plates 94-1, 94-2, 94-3 having an opening portion formed in a central portion. The time division mirrors 90-1, 90-2 are composed of a glass substrate, and a mirror 92 is arranged in, for example, 1 / 3 of the area in the surface. For example, the mirror 92 is arranged in a sector-shaped area of 120° from the center of rotation of the glass substrate. For example, the two time division mirrors 90-1 and 90-2 are arranged so as to be inclined by 45° in opposite directions to each other. The light beams 19-1, 19-2 of each inspection field and the light beam 19-3 of the AF field which have passed through the common detection optical system 172 are incident to positions deviated from the center of rotation of the first stage time division mirror 90-1. In this case, the light beams 19-1, 19-2 of each inspection field and the light beam 19-3 of the AF field are reflected in, for example, the orthogonal direction for 1 / 3 of the time during which the time division mirror 90-1 rotates one revolution, and pass through for the remaining 2 / 3 of the time. Thereby, by means of the slit plate 94-1, the light beam 19-3 of the reflected light of, for example, the AF image in the reflected light beam group passes through the opening portion, and the remaining light beams are shielded by a shield plate. Then, the light beams which have passed through the slit plate 94-1 enter the auto focus optical system 180. Further, the light beams of each inspection field and the light beam of the AF field which have passed through the time division mirror 90-1 are incident to positions deviated from the center of rotation of the second stage time division mirror 90-2. Then, the light beams 19-1, 19-2 of each inspection field and the light beam 19-3 of the AF field are reflected in, for example, the orthogonal direction for 1 / 3 of the time during which the time division mirror 90 rotates one revolution, and pass through for the remaining 2 / 3 of the time. Thereby, in the light beam group reflected by the slit plate 94, the light beam 19-2 of the transmitted light of the slit image of, for example, the transmission field passes through the opening portion, and the remaining light beams are shielded by a shield plate. The light beam 19-2 which has passed through the slit plate 94 enters the detection optical system 276. In addition, by means of the slit plate 94-3, the light beam 19-1 of the reflected light of the slit image of, for example, the reflection field in the transmitted light beam group passes through the opening portion, and the remaining light beams are shielded by a shield plate. The light beam 19-1 which has passed through the slit plate 94-3 enters the detection optical system 176. By synchronizing the phases of the time division mirrors 90-1, 90-2 during rotation, and adjusting the positions of the mirrors 92 during rotation so as not to overlap, it is possible to divide the light beams in, for example, 1 / 3 of the time during one revolution. Thereby, it is possible to separate each light beam in time division.

[0100] Figure 7 FIG. 1 is a diagram showing an example of the structure of the image pickup sensor in Embodiment 1. The image pickup sensor 105 has a plurality of detection elements 1 (first detection elements). Similarly, the image pickup sensor 205 has a plurality of detection elements 1 (second detection elements).

[0101] A portion of the plurality of detection elements 1 of the camera sensor 105, namely detection elements 3a, 3b, and 3c, are used as elements constituting the detection unit 6 (first detection unit). The remaining plurality of detection elements 2 are used as the sensor 4 for image acquisition. The detection unit 6 also has an optical element 8 (first optical element).

[0102] A portion of the multiple detection elements 1 of the camera sensor 205, including multiple detection elements 3a, 3b, and 3c, are used as elements constituting the detection unit 7 (second detection unit). The remaining multiple detection elements 2 are used as the sensor 5 for image acquisition. The detection unit 7 also includes an optical element 9 (second optical element).

[0103] Optical element 8 (9) is disposed, for example, near the optical path of detection elements 3b and 3c. Optical elements 8 and 9 are formed, for example, from a block of glass material, with the thickness of the portion through which light incident on detection element 3b passes being different from the thickness of the portion through which light incident on detection element 3c passes. The light passing through the block of glass material travels parallel without focusing. Thus, the focal points of the light incident on detection element 3a, the light incident on detection element 3b, and the light incident on detection element 3c in the beam imaged by imaging lens 179 (279) can be staggered. Figure 7 In the example, when a light beam focused at position A of the detection surface of detection element 3a is incident on the image sensor 105 (205), in detection element 3a, the image is incident at the same focal position A as each detection element 2 of the image capturing sensor 4 (5). In detection element 3b, the image is incident at position B, which is further back than each detection element 2 of the image capturing sensor 4 (5). In detection element 3c, the image is incident at position C, which is further back than detection element 3b. Therefore, in detection units 6 and 7, images with three different focal positions can be generated and detected.

[0104] The detection unit 6 (first detection unit) detects, for example, changes in the positional relationship (first positional relationship) between the focal position of a light beam 19-1 (first beam) reflected by the reflective illumination field of view and formed by the detection optical system 176 and the image sensor 105. The detection unit 6 (an example of the first detection mechanism) uses, for example, the light beam 19-1 that has passed through the optical element 8 to detect changes in the positional relationship between the focal position of the light beam 19-1 and the image sensor 105. Furthermore, the detection unit 6 (an example of the first detection mechanism) uses, for example, grayscale data detected by receiving a portion of the light beam 19-1 by a portion of the plurality of detection elements 1 of the image sensor 105 to detect changes in the positional relationship between the focal position of the light beam 19-1 and the image sensor 105.

[0105] The detection unit 7 (second detection unit) detects, for example, changes in the positional relationship (second positional relationship) between the focal position of the light beam 19-2 (second light beam) that passes through the transmitted illumination field of view and is imaged by the detection optical system 276 and the image sensor 205. The detection unit 7 (an example of the second detection mechanism) detects changes in the positional relationship between the focal position of the light beam 19-2 and the image sensor 205, for example, using the light beam 19-2 that has passed through the optical element 9. Furthermore, the detection unit 7 (an example of the second detection mechanism) detects changes in the positional relationship between the focal position of the light beam 19-2 and the image sensor 205, for example, using grayscale data detected by receiving a portion of the light beam 19-2 by a portion of the plurality of detection elements 1 of the image sensor 205.

[0106] Figure 8 This is a diagram illustrating an example of a focus detection method using a portion of the camera sensor described in Embodiment 1. Figure 8 The example shown illustrates a case where a line and spacing pattern are scanned, revealing the grayscale profile of an image detected by detection elements 3a, 3b, and 3c. For instance, the grayscale difference between the grayscale value (maximum value) of the white pattern and the grayscale value (minimum value) of the black pattern is measured. Through the scanning action, the grayscale values ​​of each pixel are accumulated, thus obtaining a profile. The height position on the optical axis where the profile with the largest grayscale difference is obtained is the position with the highest image contrast, and therefore the focal point. Figure 8 In the example, the grayscale difference obtained by detection element 3b is the largest. Then, the grayscale difference obtained by detection element 3c continues, and the grayscale difference obtained by detection element 3a is the smallest. The contour where the grayscale difference is largest by detection element 3a is the design focal point position. Therefore, by fitting the grayscale differences in each detection element, the offset of the focal point position from position A of detection element 3a can be calculated. Figure 7 In the detection section 6(7), for example, after obtaining Figure 8 In the case of the measurement results of the example, it is possible to calculate the sum of the lengths of the beam of the object being detected, which is located on the optical axis closer to the detection surface of the detection element 3a than the length of the beam from position A to position B and the length of the beam from position B to position C.

[0107] Furthermore, for example, even if the focal position of the beam of the object being detected is located behind the optical axis of the detection surface of the detection element 3a, the offset can be calculated by fitting the same method as long as the grayscale difference of the black and white pattern in the state of pit alignment is measured in advance.

[0108] In addition, Figure 7 The example shows a configuration of individual detection elements for focus detection, but it is not limited to this. Multiple detection elements can also be configured at each position in a direction orthogonal to the scanning direction.

[0109] Figure 9 This is a diagram illustrating another example of the structure of the camera sensor in Embodiment 1. Figure 9 In this example, a portion of the plurality of detection elements 1 of the camera sensor 105, namely detection elements 3a, 3b, and 3c, are used as elements constituting the detection unit 6 (first detection unit, first detection mechanism), while the remaining plurality of detection elements 2 are used as the sensor 4 for image capture. At least one of this portion of the plurality of detection elements 3a, 3b, and 3c is positioned at a height different from the other detection elements 2 along the optical axis. Figure 9 In the example, detection element 3a is positioned at the same height A on the optical axis as detection element 2. Detection element 3b is positioned at a height B further rearward on the optical axis than detection element 3a. Detection element 3c is positioned at a height C further rearward on the optical axis than detection element 3b.

[0110] Similarly, a portion of the plurality of detection elements 1 of the camera sensor 205, namely detection elements 3a, 3b, and 3c, are used as elements constituting the detection unit 7 (second detection unit, second detection mechanism), and the remaining plurality of detection elements 2 are used as the sensor 5 for image capture. At least one of this portion of the plurality of detection elements 3a, 3b, and 3c is positioned at a height different from the other detection elements 2 along the optical axis. Figure 9 In the example, detection element 3a is positioned at the same height A on the optical axis as detection element 2. Detection element 3b is positioned at a height B further rearward on the optical axis than detection element 3a. Detection element 3c is positioned at a height C further rearward on the optical axis than detection element 3b. Figure 9 In the example, the detection element is positioned at a height that is the same as or further behind the detection element 2 on the optical axis, but it is not limited to this. The detection element can also be positioned at a height that is closer to the front of the detection element 2 on the optical axis. Alternatively, by positioning the detection element at a height that is closer to the front of the detection element 2 on the optical axis, at the same height as the detection element 2, and at a height that is further behind the detection element 2 on the optical axis, detection can be performed at three points: the front focal point, the designed focal point, and the rear focal point.

[0111] By shifting the height position on the optical axis, light at different focal points can be detected. Figure 9 In the detection section 6(7), for example, after obtaining Figure 8 In the case of the measurement results of the example, it is possible to calculate the sum of the length of the beam focal position of the object being detected, which is located further back on the optical axis than the detection surface of the detection element 3a, from position A to position B and the length of the midpoint between position B and position C.

[0112] Here, the inspection apparatus 100 in Embodiment 1 has autofocus functions in three locations: the focus adjustment function in the shared detection optical system 172, the focus adjustment function in the detection optical system 176, and the focus adjustment function in the detection optical system 276. For example, the inspection light 14 for reflection inspection and the measurement light 16 for focus adjustment in the shared detection optical system 172 illuminate the substrate 101 through the same reflection illumination optical system 171, so the focal position is likely to be the same. In contrast, the inspection light 15 for transmission inspection illuminates the substrate through a different optical system, so the focal position is likely to shift. Therefore, if only the focus adjustment in the shared detection optical system 172 is performed, the focal position of at least one of the inspection light 14 for reflection inspection and the inspection light 15 for transmission inspection is likely to shift. Therefore, in Embodiment 1, for example, when acquiring two different optical images, a reflection inspection image and a transmission inspection image, the image is captured while at least two of the focus adjustment functions in the shared detection optical system 172, the detection optical system 176, and the detection optical system 276 are in focus. The following is a detailed explanation.

[0113] Figure 10 This is a block diagram illustrating an example of the internal structure of the autofocus control circuit in Embodiment 1. Figure 10 In the case of the autofocus control circuit 140, there are storage devices such as disk drives 51, 53, 61, and 65, an autofocus (AF) signal calculation unit 50, a common detection optical system offset 1 calculation unit 52, a common detection optical system offset 2 calculation unit 54, a common detection optical system autofocus processing unit 56, a determination unit 58, a detection optical system 1 offset calculation unit 62, a detection optical system 1 autofocus processing unit 64, a detection optical system 2 offset calculation unit 66, and a detection optical system 2 autofocus processing unit 68.

[0114] The series of units, including an autofocus (AF) signal calculation unit 50, a common detection optical system offset 1 calculation unit 52, a common detection optical system offset 2 calculation unit 54, a common detection optical system autofocus processing unit 56, a determination unit 58, a detection optical system 1 offset calculation unit 62, a detection optical system 1 autofocus processing unit 64, a detection optical system 2 offset calculation unit 66, and a detection optical system 2 autofocus processing unit 68, has processing circuitry. This processing circuitry includes electrical circuits, a computer, a processor, a circuit board, a quantum circuit, or a semiconductor device. Alternatively, each unit may use a common processing circuit (the same processing circuit), or different processing circuits (separate processing circuits). The input data or calculated results required by the autofocus (AF) signal calculation unit 50, the common detection optical system offset 1 calculation unit 52, the common detection optical system offset 2 calculation unit 54, the common detection optical system autofocus processing unit 56, the determination unit 58, the detection optical system 1 offset calculation unit 62, the detection optical system 1 autofocus processing unit 64, the detection optical system 2 offset calculation unit 66, and the detection optical system 2 autofocus processing unit 68 are stored each time in a memory (not shown) or memory 111 within the autofocus control circuit 140.

[0115] Figure 11 This is a flowchart illustrating an example of the main steps in the inspection method of Implementation Method 1. Figure 11 In the inspection method of Implementation 1, a series of steps are performed, including image acquisition (S101), reference image production (S200), and comparison (S300).

[0116] The image acquisition process (S101) includes the following internal processes: scanning process (S102), substrate height measurement process (S104), common detection optical system offset 1 calculation process (S106), light intensity measurement process (S114), common detection optical system offset 2 calculation process (S116), grayscale measurement process (S124), detection optical system 1 offset calculation process (S126), grayscale measurement process (S134), detection optical system 2 offset calculation process (S136), maximum offset determination process (S140), and common detection optical system offset 1 calculation process (S102). The system adjustment process (S150), grayscale measurement process (S151), grayscale measurement process (S152), offset calculation process for detection optical system 1 (S153), offset calculation process for detection optical system 2 (S154), adjustment process for detection optical system 1 (S155), adjustment process for detection optical system 2 (S156), adjustment process for detection optical system 1 (S160), adjustment process for detection optical system 2 (S162), adjustment process for detection optical system 2 (S170), and adjustment process for detection optical system 1 (S172) are a series of processes.

[0117] As part of the image acquisition process (S101), the autofocus control circuit 140 controls at least two of the autofocus mechanism 131, drive mechanism 135, and drive mechanism 235 based on changes in the relationship between the focal position of beam 19-1 and the position of the camera sensor 105, changes in the relationship between the focal position of beam 19-2 and the position of the camera sensor 205, and changes in the relationship between the focal position of beam 19-3 and the focal position on the substrate 101 side of the common detection optical system 172. This adjusts at least two of these relationships. Furthermore, with at least two of the autofocus mechanism 131, drive mechanism 135, and drive mechanism 235 under control, the optical image acquisition mechanism 150, while the substrate 101 to be inspected is placed on the XYθ stage 102, receives the light reflected from the substrate 101 to be inspected by the camera sensor 105 via the detection optical system 176, and receives the light transmitted through the substrate 101 to be inspected via the camera sensor 205 via the detection optical system 276, thereby simultaneously capturing an optical image that becomes a reflected inspection image of the substrate 101 to be inspected and an optical image that becomes a transmitted inspection image.

[0118] Furthermore, the autofocus control circuit 140 determines the positional relationship with the largest change among the changes in the relationship between the focal position of beam 19-1 and the position of image sensor 105, the relationship between the focal position of beam 19-2 and the position of image sensor 205, and the relationship between the focal position of beam 19-3 and the focal position on the substrate 101 side of the shared detection optical system 172. The autofocus control circuit 140 controls at least two of the autofocus mechanism 131, drive mechanism 135, and drive mechanism 235 in such a way that the positional relationship with the largest change is adjusted first. Specifically, it operates as follows.

[0119] As part of the scanning process (S102), the camera sensor 105 receives a beam of light 19-1 transmitted or reflected from a certain field of view (first region) (e.g., a reflective illumination field of view) of a substrate 101 with a pattern formed on it, which is placed on the XYθ stage 102, thereby capturing an optical image (first optical image) of the substrate 101. Figure 1 In the example, the camera sensor 105 captures a reflection inspection image (first optical image) of the substrate 101 by receiving a light beam 19-1 reflected in the reflective illumination field of view of the substrate 101.

[0120] Additionally, at the same timing as the receiving timing of the camera sensor 105, the camera sensor 205 receives the light beam 19-2 transmitted or reflected in another field of view (second region) of the substrate 101, thereby capturing an optical image (second optical image) of the substrate 101. Figure 1 In the example, the camera sensor 205 captures a transmission inspection image (second optical image) of the substrate 101 by receiving a beam of light 19-2 that transmits through the transmission illumination field of view of the substrate 101.

[0121] The image of the pattern formed on the camera sensor 105 is photoelectrically converted by the photoelectric sensor elements of the camera sensor 105 and then converted by the sensor circuit 106 via A / D (analog-to-digital) conversion. The pixel values ​​of the test strip 20 of the measured object are then stored in the strip pattern memory 123. The measurement data (pixel data) is, for example, 8-bit unsigned data representing the brightness level (light intensity) of each pixel. The strip data, along with the position information measured by the position circuit 107, is output to the comparison circuit 108a.

[0122] The image of the pattern projected onto the camera sensor 205 is photoelectrically converted by the photoelectric sensor elements of the camera sensor 205 and then converted by the sensor circuit 206 via A / D (analog-to-digital) conversion. The pixel values ​​of the test strip 20 of the measured object are then stored in the strip pattern memory 223. The measurement data (pixel data) is, for example, 8-bit unsigned data representing the brightness level (light intensity) of each pixel. The strip data, along with the position information measured by the position circuit 107, is output to the comparison circuit 108b.

[0123] During the scanning process (S102), the following autofocus action is performed simultaneously.

[0124] Here, the focal position on the substrate 101 side of the objective lens constituting the magnifying optical system 104 and the focal position in the design of the autofocusing optical system 180 are set as conjugates. Therefore, when the height position of the pattern forming surface of the substrate 101 shifts from the focal position on the substrate 101 side of the objective lens constituting the magnifying optical system 104, the focal position of the beam 19-3, which becomes the reflected image of the AF image detected by the autofocusing optical system 180, also shifts. In other words, the positional relationship between the focal position of the beam 19-3 (the third beam) reflected from the AF field of view and separated by the separation mirror and the focal position on the substrate 101 side of the shared detection optical system 172 changes. Therefore, the light quantity data (light intensity data) at the front focal position and the light quantity at the rear focal position, which are used to obtain the offset of the focal position of the beam 19-3 reflected from the AF field of view region of the substrate 101 used for detecting the focal position of the beam 19-3, become parameters for detecting the change in the positional relationship (third positional relationship) between the focal position of the beam 19-3 reflected from the AF field of view region of the substrate 101 and the focal position on the substrate 101 side of the common detection optical system 172.

[0125] Furthermore, the offset of the height position of the pattern forming surface of the substrate 101 from the focal position of the objective lens constituting the magnifying optical system 104 can also be used as a parameter to detect the change in the positional relationship (third positional relationship) between the focal position of the beam 19-3 reflected from the AF field of view of the substrate 101 and the focal position of the common detection optical system 172 on the substrate 101 side.

[0126] The height position of the patterned surface of substrate 101 is detected by position sensor 134. The amount of light at the front focal position is detected by light quantity sensor 185. The amount of light at the rear focal position is detected by light quantity sensor 187. Therefore, the confocal sensor including light quantity sensor 185 and light quantity sensor 187 becomes an example of a detection unit (third detection unit) that detects the change in the positional relationship (third positional relationship) between the focal position of the beam 19-3 reflected from the AF field of view region of substrate 101 and the focal position of the common detection optical system 172 on the substrate 101 side. In other words, the confocal sensor measures the amount of light at the front focal position and the amount of light at the rear focal position of beam 19-3, and uses the amount of light at the front focal position and the amount of light at the rear focal position of beam 19-3 to detect the change in the positional relationship between the focal position of beam 19-3 and the focal position of the common detection optical system 172 on the substrate 101 side. In addition, the position sensor 134 is another example of a detection unit (third detection unit) that detects the change in the positional relationship (third positional relationship) between the focal position of the light beam 19-3 reflected from the AF field of view area of ​​the substrate 101 and the focal position of the common detection optical system 172 on the substrate 101 side.

[0127] Furthermore, the parameter used to detect the change in the relationship (first positional relationship) between the focal position of the light beam 19-1 reflected from the reflective illumination field of view of the substrate 101 and the position of the image sensor 105 is grayscale data detected by the detection unit 6 (first detection unit). The parameter used to detect the change in the relationship (second positional relationship) between the focal position of the light beam 19-2 transmitted in the transmissive illumination field of view of the substrate 101 and the position of the image sensor 205 is grayscale data detected by the detection unit 7 (second detection unit).

[0128] Therefore, the parameters used to detect changes (offsets) in these positional relationships are measured (detected), and the respective offsets are calculated based on these parameters. Specifically, the operation is performed as follows.

[0129] As part of the substrate height measurement process (S104), the position sensor 134 measures the height position of the pattern forming surface of the substrate 101. The measured height position of the pattern forming surface of the substrate 101 (mask surface height position) is output to the autofocus control circuit 140 and stored in the storage device 53.

[0130] As part of the common detection optical system offset 1 calculation step (S106), the common detection optical system offset 1 calculation unit 52 reads the height position data of the pattern forming surface of the substrate 101 from the storage device 53 and calculates the offset (common detection optical system offset 1) from a preset reference height position. The reference height position is set as the focal position on the substrate 101 side of the magnifying optical system 104.

[0131] As part of the light intensity measurement process (S114), the light intensity at the front focal position of the light beam 19-3 incident on the autofocus optical system 180 is measured using the light intensity sensor 185, and the light intensity at the rear focal position is measured using the light intensity sensor 187. The light intensity data (light intensity data) at the front focal position and the rear focal position are output to the autofocus control circuit 140 and stored in the storage device 51.

[0132] As part of the common detection optical system offset 2 calculation step (S116), the common detection optical system offset 2 calculation unit 54 first calculates the autofocus signal used by the common detection optical system. The autofocus signal εi used by the common detection optical system can be calculated by the sum and difference of the light quantity Ai at the front focal position and the light quantity Bi at the rear focal position. The autofocus signal εi is defined by the following formula (1). i represents the index.

[0133] (1) εi=(Ai-Bi) / (Ai+Bi)

[0134] Next, the common detection optical system offset 2 calculation unit 54 calculates the amount of movement (offset) of the height position of the pattern forming surface of the substrate 101 used to make the calculated autofocus signal εi zero as the common detection optical system offset 2.

[0135] As part of the grayscale measurement process (S124), the detection unit 6 detects the grayscale values ​​of each light beam 19-1 reflected from the reflected illumination field of view of the substrate 101 by receiving the light beams 19-1 from the detection elements 3a, 3b, and 3c of the camera sensor 105. The detected grayscale data (data from the detection optical system 1) are output to the autofocus control circuit 140 via the comparison circuit 108a and stored in the storage device 61.

[0136] As part of the offset calculation process (S126) of the detection optical system 1, the offset calculation unit 62 of the detection optical system 1 calculates the offset between the focal position of the light beam 19-1 reflected from the reflective illumination field area of ​​the substrate 101 and the detection surface of the camera sensor 105 as the offset of the detection optical system 1.

[0137] As part of the grayscale measurement process (S134), the detection unit 7 uses the detection elements 3a, 3b, and 3c of the image sensor 205 to receive the light beam 19-2 transmitted in the field of view of the transmitted illumination on the substrate 101, thereby detecting the grayscale value data of each element. The detected grayscale data (data from the detection optical system 2) is output to the autofocus control circuit 140 via the comparison circuit 108b and stored in the storage device 65.

[0138] As part of the offset calculation process (S136) of the detection optical system 2, the offset calculation unit 66 of the detection optical system 2 calculates the offset between the focal position of the light beam 19-2 transmitted in the transmission illumination field of view of the substrate 101 and the detection surface of the camera sensor 205 as the offset of the detection optical system 2.

[0139] As part of the maximum offset determination step (S140), the determination unit 58 determines the maximum offset among the common detection optical system offset 1, common detection optical system offset 2, detection optical system 1 offset, and detection optical system 2 offset. If the maximum offset is common detection optical system offset 1 or common detection optical system offset 2, the common detection optical system adjustment step (S150) is initiated. If the maximum offset is detection optical system 1 offset, the detection optical system 1 adjustment step (S160) is initiated. If the maximum offset is detection optical system 2 offset, the detection optical system 2 adjustment step (S170) is initiated.

[0140] When either the common detection optical system offset 1 or the common detection optical system offset 2 becomes the maximum offset, the operation is as follows.

[0141] As part of the common detection optical system adjustment process (S150), the autofocus mechanism 131 (third adjustment mechanism) automatically adjusts the positional relationship between the focal position of the beam 19-3 and the focal position on the substrate 101 side of the common detection optical system 172. The autofocus mechanism 131 adjusts the height relationship between the pattern forming surface of the substrate 101 and the objective lens by moving the objective lens constituting the substrate 101 or the magnifying optical system 104, so that the beam 19-3 is focused at the designed focal position. Figure 1 In one example, the autofocus processing unit 56 of the shared detection optical system drives the Z-drive mechanism 132 to move the height position of the XYθ stage 102 so that the autofocus signal εi is zero. This moves the height position of the pattern forming surface of the substrate 101 placed on the XYθ stage 102 to coincide with the focal position on the substrate 101 side of the shared detection optical system 172. Therefore, the positional relationship between the focal position of the beam 19-3 and the focal position on the substrate 101 side of the shared detection optical system 172 can be made conjugate.

[0142] As part of the grayscale measurement process (S151), the detection unit 6 detects the adjusted grayscale values ​​in the common detection optical system 172 by receiving the light beams 19-1 reflected from the reflected illumination field of view of the substrate 101 by the detection elements 3a, 3b, and 3c of the camera sensor 105.

[0143] As part of the grayscale measurement process (S152), the detection unit 7 detects the adjusted grayscale values ​​in the common detection optical system 172 by receiving the light beams 19-2 transmitted in the transmitted illumination field of view of the substrate 101 by the detection elements 3a, 3b, and 3c of the camera sensor 205.

[0144] As part of the offset calculation process (S153) of the detection optical system 1, the offset calculation unit 62 of the detection optical system 1 calculates the offset between the focal position of the beam 19-1 reflected from the reflective illumination field area of ​​the substrate 101 after adjustment by the common detection optical system 172 and the detection surface of the camera sensor 105 as the offset of the detection optical system 1.

[0145] As part of the offset calculation process (S154) of the detection optical system 2, the offset calculation unit 66 of the detection optical system 2 calculates the offset between the focal position of the beam 19-2 transmitted in the transmission illumination field of the substrate 101 after adjustment in the common detection optical system 172 and the detection surface of the camera sensor 205, and uses it as the offset of the detection optical system 2.

[0146] As part of the adjustment process (S155) of the detection optical system 1, the automatic focusing processing unit 64 of the detection optical system 1 controls the drive mechanism 135, which automatically adjusts the focal position of the beam 19-1 relative to the position of the image sensor 105. The drive mechanism 135 moves at least one of the collimating lens 178, the imaging lens 179, and the image sensor 105 to align the focal position of the beam 19-1 with the detection surface of the image sensor 105. Figure 1 and Figure 2 In one example, by using a drive mechanism 135 to move the collimating lens 178 along the optical axis, the focal point of the beam 19-1 is aligned with the detection surface of the image sensor 105. Thus, the detection optical system 176 images the separated beam 19-1 onto the image sensor 105.

[0147] As part of the adjustment process (S156) of the detection optical system 2, the automatic focusing processing unit 68 of the detection optical system 2 controls the drive mechanism 235, which automatically adjusts the focal position of the beam 19-2 and its positional relationship with the image sensor 205. The drive mechanism 235 moves at least one of the collimating lens 278, the imaging lens 279, and the image sensor 205 to align the focal position of the beam 19-2 with the detection surface of the image sensor 205. Figure 2 In one example, the collimating lens 278 is moved along the optical axis by the drive mechanism 235, thereby aligning the focal point of the beam 19-2 with the detection surface of the image sensor 205. Thus, the detection optical system 276 images the separated beam 19-2 onto the image sensor 205.

[0148] Furthermore, the height position of the focus point during the scanning operation is the leading edge of the film constituting the pattern in the patterned area. The common detection optical system adjustment process (S150) detects the amount of movement of the height position of the pattern forming surface, but as the amount of movement increases, the movement error caused by the nonlinearity of the signal becomes significant. On the other hand, in order to determine the height position of the glass substrate surface, the position sensor 134 cannot simply align with the focus position because there is a difference between the substrate surface and the leading edge of the film. However, the amount of movement of the height position of the glass substrate measured by the position sensor 134 remains sufficiently linear even as the amount of movement increases. Therefore, when the amount of movement of the height position of the pattern forming surface increases, the output of the position sensor 134 becomes larger than the output of the common detection optical system adjustment process (S150). As a result, when the offset of the glass substrate surface from the reference height position becomes the largest of the four offsets, the common detection optical system 172 is aligned first, and then the offsets of the detection optical system 1 and the detection optical system 2 are aligned. This allows for the adjustment of the detection optical system 1 and the detection optical system 2 through fine adjustments. This also applies to the case where the offset of the detection result based on the confocal sensor (the offset 2 of the shared detection optics system) is the maximum offset.

[0149] If the offset of the detection optical system 1 is the maximum offset, the following actions are performed.

[0150] As part of the adjustment process (S160) of the detection optical system 1, the adjustment in the common detection optical system 172 is not performed. The automatic focusing processing unit 64 of the detection optical system 1 controls the drive mechanism 135, which automatically adjusts the focal position of the beam 19-1 and the positional relationship with the image sensor 105. The drive mechanism 135 only needs to move at least one of the collimating lens 178, the imaging lens 179, and the image sensor 105; this is consistent across all cases. Figure 1 and Figure 2 In one example, by using a drive mechanism 135 to move the collimating lens 178 along the optical axis, the focal point of the beam 19-1 is aligned with the detection surface of the image sensor 105. Thus, the detection optical system 176 images the separated beam 19-1 onto the image sensor 105.

[0151] Furthermore, as part of the adjustment process (S162) for the detection optical system 2, the adjustment in the shared detection optical system 172 is not performed. The automatic focusing processing unit 68 of the detection optical system 2 controls the drive mechanism 235, which automatically adjusts the focal position of the beam 19-2 and the positional relationship with the image sensor 205. The drive mechanism 235 only needs to move at least one of the collimating lens 278, the imaging lens 279, and the image sensor 205; this is consistent with the previous process. Figure 2In one example, the collimating lens 278 is moved along the optical axis by the drive mechanism 235, thereby aligning the focal point of the beam 19-2 with the detection surface of the image sensor 205. Thus, the detection optical system 276 images the separated beam 19-2 onto the image sensor 205.

[0152] When the offset of the detection optical system 2 is at its maximum, the operation is performed as follows.

[0153] As part of the adjustment process (S170) of the detection optical system 2, the adjustment in the shared detection optical system 172 is not performed. The automatic focusing processing unit 68 of the detection optical system 2 controls the drive mechanism 235, which automatically adjusts the focal position of the beam 19-2 and the positional relationship with the image sensor 205. The drive mechanism 235 only needs to move at least one of the collimating lens 278, the imaging lens 279, and the image sensor 205; this is consistent with the previous process. Figure 2 In one example, the collimating lens 278 is moved along the optical axis by the drive mechanism 235, thereby aligning the focal point of the beam 19-2 with the detection surface of the image sensor 205. Thus, the detection optical system 276 images the separated beam 19-2 onto the image sensor 205.

[0154] Furthermore, as part of the adjustment process (S172) for the detection optical system 1, the adjustment in the common detection optical system 172 is not performed. The automatic focusing processing unit 64 of the detection optical system 1 controls the drive mechanism 135, which automatically adjusts the focal position of the beam 19-1 and the positional relationship with the image sensor 105. The drive mechanism 135 only needs to move at least one of the collimating lens 178, the imaging lens 179, and the image sensor 105; this is consistent with the previous process. Figure 1 and Figure 2 In one example, by using a drive mechanism 135 to move the collimating lens 178 along the optical axis, the focal point of the beam 19-1 is aligned with the detection surface of the image sensor 105. Thus, the detection optical system 176 images the separated beam 19-1 onto the image sensor 105.

[0155] When the offset of detection optical system 1 or detection optical system 2 is at its maximum, even if adjustments are made in the shared detection optical system 172, the remaining adjustment amount is still relatively large. Therefore, individual adjustments can avoid or reduce adjustment delays relative to the scanning operation.

[0156] As described above, in Embodiment 1, with at least two of the following focus adjustments performed: focus adjustment in the shared detection optical system 172, focus adjustment in the detection optical system 176, and focus adjustment in the detection optical system 276, the optical image acquisition mechanism 150 simultaneously captures two different optical images of each inspection strip 20.

[0157] As part of the reference image creation process (S200), the reference image creation circuit 112 uses graphic pattern data (design data) to create a reference image for reference. The creation of the reference image is performed in parallel with the scanning operation of each inspection strip 20 of the substrate 101 being inspected. Specifically, the operation is performed as follows: The reference image creation circuit 112 inputs graphic pattern data (design data) for each frame region 30 of the inspection strip 20 to be inspected, and transforms each graphic pattern defined in the graphic pattern data into binary or multi-valued image data.

[0158] The graphic pattern data defines a graphic as a basic shape, such as a rectangle or triangle. For example, the data stores graphic data that uses information such as the coordinates (x, y) of the graphic's reference position, the length of the side, and the graphic code as an identifier to distinguish between different types of graphics, such as rectangles or triangles, to define the shape, size, position, etc. of each graphic pattern.

[0159] When the design pattern data, which becomes the graphic data, is input to the reference image fabrication circuit 112, it is expanded to the data of each graphic, and the graphic code representing the graphic shape, graphic size, etc., of the graphic data are interpreted. Then, as a pattern arranged in squares with a grid of a specified quantization size, it is expanded into binary or multi-valued design pattern image data and output. In other words, design data is read in, and for each square obtained by virtually dividing the frame area into squares of a specified size, the occupancy rate of the graphic in the design pattern is calculated, and n bits of occupancy rate data (design image data) are output. For example, it is preferable to set one square as one pixel. Moreover, if one pixel has 1 / 2 8 For a resolution of (1 / 256), a small region of 1 / 256 of the area of ​​the graphic within a pixel is allocated to calculate the occupancy within the pixel. Then, 8 bits of occupancy data are generated. This square (check pixel) should match the pixel in the measured data.

[0160] Next, referring to the image fabrication circuit 112, a filtering function is used to perform filtering processing on the design image data of the design pattern, which is the graphic image data.

[0161] Figure 12This diagram illustrates the filtering process in Embodiment 1. The pixel data of the optical image captured from the substrate 101 being inspected is in a state where the filter is active, depending on the resolution characteristics of the optical system used for capture, etc. In other words, it is in a continuously changing analog state, therefore, for example... Figure 13 As shown, the image intensity (darkness value) differs from the unfolded image (design image) with digital values. On the other hand, in graphic pattern data, as described above, it is defined by graphic codes, etc., so the image intensity (darkness value) may be a digital value in the unfolded design image. Therefore, the image processing circuit 112 performs image processing (filtering) on ​​the unfolded image to create a reference image that approximates an optical image. Thus, it is possible to make the image generation characteristics of the design image data (design image data) with digital image intensity (darkness value) consistent with those of the measurement data (optical image). The created reference image is output to the comparison circuits 108a and 108b.

[0162] Figure 13 This is a diagram illustrating an example of the internal structure of the comparator circuit in Embodiment 1. Figure 13 In this system, storage devices such as disk drives 70, 72, and 76, a frame image creation unit 74, a registration unit 78, and a comparison processing unit 79 are arranged within the comparison circuits 108 (108a, 108b). Each of these "~units," including the frame image creation unit 74, the registration unit 78, and the comparison processing unit 79, has processing circuitry. This processing circuitry may include electrical circuits, a computer, a processor, a circuit board, a quantum circuit, or a semiconductor device. Alternatively, each "~unit" may use a common processing circuit (the same processing circuit), or different processing circuits (separate processing circuits). The input data required by the frame image creation unit 74, the registration unit 78, and the comparison processing unit 79, or the results of their calculations, are stored each time in a memory (not shown) or a memory 111 within the comparison circuit 108.

[0163] The strip data (strip area image) for reflection inspection input to the comparison circuit 108a is stored in the storage device 70. The reference image data input to the comparison circuit 108a is stored in the storage device 72.

[0164] The strip data (strip area image) for transmission inspection input to the comparison circuit 108b is stored in the storage device 70. The reference image data input to the comparison circuit 108b is stored in the storage device 72.

[0165] The comparison process (S300) and comparison circuit 108a (an example of a comparison unit) compare the captured optical image with the reference image using the reference image and output the result. Similarly, comparison circuit 108b (an example of a comparison unit) compares the captured optical pixels with the reference image using the reference image and outputs the result. The comparison processing for transmission inspection and the comparison processing for reflection inspection are the same. Specifically, the operation is performed as follows.

[0166] In the comparison circuits 108 (108a, 108b), firstly, the frame image generation unit 74 generates multiple frame images 31 that divide the stripe region image (optical image) by a predetermined width. Specifically, as... Figure 2 As shown, the striped region image is divided into multiple rectangular frame regions 30. For example, it is divided into 512×512 pixel dimensions. The data of each frame region 30 is stored in the storage device 76.

[0167] Next, the alignment unit 78 reads the corresponding frame image 31 and the corresponding reference image from the storage devices 72 and 76 for each frame region 30, and performs alignment of the frame image 31 and the corresponding reference image using a predetermined algorithm. For example, alignment is performed using the least squares method.

[0168] Then, the comparison processing unit 79 (another example of a comparison unit) compares the frame image 31 with the reference image corresponding to the frame image 31. For example, it compares each pixel. Here, each pixel is compared according to a predetermined determination condition, such as determining whether there is a defect like a shape defect. As a determination condition, for example, each pixel is compared according to a predetermined algorithm to determine whether there is a defect. For example, the difference between the pixel values ​​of the two images is calculated for each pixel, and a defect is determined if the difference value is greater than a threshold Th. The comparison result can be output to, for example, a disk drive 109, a magnetic tape drive 115, a floppy disk drive (FD) 116, a CRT 117, a pattern monitor 118, or a printer 119.

[0169] The above example illustrates a die-to-database check, but a die-to-die check is also possible. In this case, the comparison circuit 108 (108a, 108b) uses the frame image (optical image) of the die 2 obtained for one of the frame regions 30 undergoing the die-to-die check as a reference (reference image). First, the alignment unit 78 reads the corresponding frame image 31 of the die 1 and the frame image of the die 2 from the storage device 76 for each frame region 30 undergoing the die-to-die check, and aligns the frame images 31 of the die 1 and the frame images of the 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 corresponding frame image 31 of the die 1 and the frame image of the die 2 for each pixel in each frame region 30 undergoing the die-to-die check.

[0170] As described above, according to Embodiment 1, even when multiple inspection images are captured simultaneously using different camera sensors, the focal points of the beams 19-1 and 19-2 of each inspection optical system 176 and 276 can be focused on each camera sensor.

[0171] Implementation Method 2

[0172] In Embodiment 1, a structure for simultaneously performing reflection and transmission inspection was described, but it is not limited to this. In Embodiment 2, a structure for simultaneously performing two different reflection inspections is described. Hereinafter, except for points specifically noted, the content is the same as in Embodiment 1.

[0173] Figure 14 This is a structural diagram illustrating an example of the structure of the pattern inspection device in Embodiment 2.

[0174] Figure 15 This is a structural diagram showing an example of the structure of the reflective illumination optical system and an example of the detection optical system in Embodiment 2.

[0175] exist Figure 14 and Figure 15 Except for the absence of a transmission illumination optical system 170, and the addition of a concave lens 17, a convex lens 18, a slit plate 46-2, and a half-wavelength plate 41 in the reflection illumination optical system 171 instead of the slit plate 46-1, it is otherwise similar to... Figure 1 and Figure 2 same.

[0176] For example, in an EUV mask inspection apparatus, the substrate 101 is illuminated with multiple different polarization states, and a reflection inspection image for each polarization state is acquired simultaneously. The inspection apparatus 100 in Embodiment 2, for example, can be used for simultaneous inspection using reflection inspection images for each polarization state.

[0177] The reflective illumination optical system 171 includes a half-wave plate 40, a Rosen prism 42, a collimating lens 44, a half-wave plate 49, a half-wave plate 45, a concave lens 17, a convex lens 18, a slit plate 46-2, a half-wave plate 41, and a lens 43.

[0178] exist Figure 15 In the example, the polarization direction (electric field vibration direction) of the light 11 incident on the reflective illumination optical system 171 is adjusted to a certain direction by an optical element not shown. For example, light 11 (P-wave) with a polarization direction of 90 degrees from the x-axis is incident on the reflective illumination optical system 171 relative to a plane (xz plane) orthogonal to the direction of travel of the light 11.

[0179] The polarization direction of the light 11 (first light) incident on the half-wave plate 40 is changed by adjusting the angle of the half-wave plate 40. At this time, as... Figure 2 As shown, the angle is adjusted to accommodate a higher proportion of P-wave components, used as the inspection light, and a lower proportion of S-wave components, used as the measurement light for autofocus. Light 12, containing both P-wave and S-wave components, output from the half-wave plate 40, is incident on the Rosen prism 42, separating the tracks of the P-wave and S-wave components. For example, the P-wave component is output in a straight line, while the S-wave component is output at an angle. This separates the light into an inspection light 14 and a measurement light 16. Both the inspection light 14 and the measurement light 16 are incident on the collimating lens 44 and refracted to form parallel tracks. For example, the inspection light 14 passes through the center of the collimating lens 44 and is output in a straight line. The measurement light 16 passes through the outer periphery of the collimating lens 44, is refracted in the focusing direction, and is output in a direction parallel to the inspection light 14.

[0180] The inspection light 14, passing through the collimating lens 44, becomes polarized, for example, in the direction of a P-wave, while the measurement light 16, also passing through the collimating lens 44, becomes polarized, for example, in the direction of an S-wave. Therefore, the measurement light 16 is incident on the half-wave plate 49, converted into light with the same polarization direction as the inspection light 14 (e.g., a P-wave), and output. Both the inspection light 14 and the measurement light 16 are incident on the half-wave plate 45 and are both converted into, for example, S-waves.

[0181] The inspection light 14, passing through the half-wave plate 45, is extended in a divergent direction by the concave lens 17, and then becomes parallel light in an extended state by the convex lens 18, and is incident on the slit plate 46-2 parallel to the measurement light 16.

[0182] Two rectangular slit openings 47-1 and 47-2 are formed on the slit plate 46-2 to form two reflective fields of view for reflection inspection. Additionally, a slit opening 48 is formed on the slit plate 46-2, which restricts the passage of the measurement light (light for autofocusing) used to measure the height position offset of the substrate 101 relative to the focal height. The shape of the slit opening 48 is the same as in Embodiment 1. The extended inspection light 14 illuminates in a manner that includes both slit openings 47-1 and 47-2 as a whole. Similarly, the measurement light 16 illuminates in a manner that includes the slit opening 48 as a whole. The inspection light 13-1, passing through the first reflective field of view slit image of the slit opening 47-1, is incident on the beam splitter 174 via the lens 43, for example, with an S-wave polarization direction. The inspection light 13-2, passing through the second reflective field of view slit image of the slit opening 47-2, is incident on the beam splitter 174 via the lens 43, for example, with an S-wave polarization direction. Additionally, the measurement light 16, which passes through the autofocus slit image (AF slit image) of the slit opening 48, is incident on the beam splitter 174 via the lens 43, for example, in an S-wave polarization direction.

[0183] The inspection light 13-2, which is reflected by the beam splitter 174, is incident on the half-wave plate 41 and transformed into light with a different polarization direction than the inspection light 13-1 and then output.

[0184] The following will Figure 4 The reflected field of view is used as the first reflected illumination field of view, and the transmitted field of view is used as the second reflected illumination field of view.

[0185] The reflective illumination optical system 171 illuminates the autofocus illumination field of view (third region) of the substrate 101 using the measurement light 16 passing through the slit plate 46. The reflective illumination optical system 171 also illuminates the first reflective illumination field of view (another example of the first region) of the substrate 101 using the inspection light 13-1. The reflective illumination optical system 171 further illuminates the second reflective illumination field of view (another example of the second region) of the substrate 101 using the inspection light 13-2, which has a different polarization direction than the inspection light 13-1. Specifically, the inspection light 13-1, inspection light 13-2, and measurement light 16 incident on the beam splitter 174 are reflected by the beam splitter 174 and illuminate the substrate 101 through the magnifying optical system 104. In other words, the shared detection optical system 172 illuminates the focused field of view of the substrate 101 under inspection using the measurement light 16 for focus adjustment.

[0186] Since the inspection light 13-1, inspection light 13-2, and measuring light 16 are imaged through the same lens, the focal height positions of the inspection light 13-1, inspection light 13-2, and measuring light 16 are the same. Thus, in reflection inspection, the beam splitter 174 and the magnifying optical system 104 function as part of the reflection illumination optical system 171.

[0187] The beam 19-4 (another example of the first beam) reflected by the first reflective illumination field area (another example of the first region) of the substrate 101, the beam 19-5 (another example of the second beam) transmitted through the second reflective illumination field area (another example of the second region) of the substrate 101, and the beam 19-3 (the third beam) reflected by the autofocus illumination field area (an example of the third region) of the substrate 101 are all guided onto the common detection optical path by the common detection optical system 172.

[0188] Specifically, the beam 19-4 reflected by the first reflective illumination field of the substrate 101, the beam 19-5 transmitted through the second reflective illumination field of the substrate 101, and the beam 19-3 reflected by the autofocus illumination field of the substrate 101 all pass through the magnifying optical system 104, beam splitter 174, and imaging lens 175, which serve as a common detection optical system 172, and travel to the splitting mirror 177. The imaging lens 175 images the three beams 19-4, 19-5, and 19-3 on the reflecting surface of the splitting mirror 177. At this time, beam 19-5 is incident on the half-wave plate 41, and after being converted into light with the same polarization direction as beam 19-4, it is incident on the beam splitter 174. Thus, beam 19-5 can pass through the beam splitter 174 together with beam 19-4.

[0189] The beam splitter 177 (an example of a beam splitting mechanism) separates the beam 19-4 reflected in the first reflective illumination field of view of the substrate 101, the beam 19-5 transmitted through the second reflective illumination field of view of the substrate 101, and the beam 19-3 reflected in the autofocus illumination field of view of the substrate 101. Specifically, the beam 19-4 reflected in the first reflective illumination field of view of the substrate 101, for example, passes through the beam splitter 177 and enters the detection optical system 176. The beam 19-5 transmitted through the second reflective illumination field of view of the substrate 101, for example, is reflected by the beam splitter 177 and enters the detection optical system 276. The beam 19-3 reflected in the autofocus illumination field of view of the substrate 101 is reflected by the beam splitter 177 and enters the autofocus optical system 180.

[0190] After separation, the beam 19-4 incident on the detection optical system 176 is imaged on the camera sensor 105 (first sensor) by means of the detection optical system 176 (first detection optical system). Specifically, the beam 19-4 incident on the detection optical system 176 is incident on the detection optical system 176 while extending in the divergent direction, is refracted into parallel light by the collimating lens 178 and enters the imaging lens 179. Furthermore, the imaging lens 179 refracts the beam 19-4 in the focusing direction, and images it on the detection surface of the camera sensor 105. The camera sensor 105 captures an optical image (first optical image) of the substrate 101 under inspection by receiving the beam 19-4 reflected in, for example, a first reflected illumination field region (first region) of the substrate 101 under inspection.

[0191] After separation, the beam 19-5 incident on the detection optical system 276 is imaged on the camera sensor 205 (second sensor) by means of the detection optical system 276 (second detection optical system). Specifically, the beam 19-5 incident on the detection optical system 276 is incident on the detection optical system 276 while extending in the divergent direction, is refracted into parallel light by the collimating lens 278 and enters the imaging lens 279. Furthermore, the imaging lens 279 refracts the beam 19-5 in the focusing direction, forming an image on the detection surface of the camera sensor 205. The camera sensor 205 receives the beam 19-5 reflected from, for example, the second reflected illumination field region (second region) of the substrate 101 under inspection at the same timing as the receiving timing of the camera sensor 105, thereby capturing an optical image (second optical image) of the substrate 101 under inspection.

[0192] The following is the same as Embodiment 1, in which "reflected illumination field of view area" is replaced with "first reflected illumination field of view area", "transmitted illumination field of view area" is replaced with "second reflected illumination field of view area", "transmission" is replaced with "reflection", "reflection inspection" is replaced with "first reflection inspection", "transmission inspection" is replaced with "second reflection inspection", "beam 19-1" is replaced with "beam 19-4", and "beam 19-2" is replaced with "beam 19-5".

[0193] As described above, according to Embodiment 2, even when illumination light with different polarization states is irradiated using the same illumination method, it is possible to capture optical images obtained from each polarization state while in focus.

[0194] The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples.

[0195] Furthermore, details regarding the device structure, control method, and other aspects not directly required in the description of this invention have been omitted, but the appropriate device structure and control method can be selected for use. For example, the control unit structure of the control inspection device 100 has been omitted, but of course, the appropriate control unit structure can be selected for use.

[0196] Furthermore, all pattern inspection devices and methods that incorporate the elements of this invention and can be appropriately modified by those skilled in the art are included within the scope of this invention.

Claims

1. A pattern inspection apparatus comprising: a stage on which a substrate on which a patterned design is formed is placed; a first sensor that captures a first optical image of the substrate by receiving a first light beam transmitted or reflected at a first region of the substrate; a second sensor that captures a second optical image of the substrate by receiving a second light beam transmitted or reflected at a second region of the substrate at the same timing as the timing at which the first sensor receives the first light beam; a common detection optical system that illuminates a third region of the substrate with light for focus adjustment and guides the first light beam, the second light beam, and a third light beam reflected at the third region of the substrate onto a common optical path of a detection system; a light beam separation mechanism that separates the first light beam, the second light beam, and the third light beam; a first detection optical system that images the separated first light beam on the first sensor; a second detection optical system that images the separated second light beam on the second sensor; a first detection mechanism that detects a change in a first positional relationship between a focal point position of the first light beam and the first sensor; a second detection mechanism that detects a change in a second positional relationship between a focal point position of the second light beam and the second sensor; a third detection mechanism that detects a change in a third positional relationship between a focal point position of the separated third light beam and a focal point position of the common detection optical system on the substrate side; a first adjustment mechanism that automatically adjusts the first positional relationship; a second adjustment mechanism that automatically adjusts the second positional relationship; a third adjustment mechanism that automatically adjusts the third positional relationship; and a control circuit that controls at least two of the first adjustment mechanism, the second adjustment mechanism, and the third adjustment mechanism based on the change in the first positional relationship, the change in the second positional relationship, and the change in the third positional relationship, to adjust at least two of the first positional relationship, the second positional relationship, and the third positional relationship.

2. The pattern inspection apparatus according to claim 1, wherein the light beam separation mechanism has a fixed mirror or a time division mirror.

3. The pattern inspection apparatus according to claim 1, wherein the third detection mechanism has a confocal sensor that receives the third light beam.

4. The pattern inspection apparatus according to claim 1, wherein the first sensor has a plurality of first detection elements, the second sensor has a plurality of second detection elements, the first detection mechanism is configured using a portion of the plurality of first detection elements, and the second detection mechanism is configured using a portion of the plurality of second detection elements.

5. The pattern inspection apparatus according to claim 1, wherein the first sensor has a plurality of first detection elements, at least one of a portion of the plurality of first detection elements is disposed at a height position in an optical axis direction that is different from other first detection elements, the second sensor has a plurality of second detection elements, at least one of a portion of the plurality of second detection elements is disposed at a height position in an optical axis direction that is different from other second detection elements, and the first detection mechanism is configured using a portion of the plurality of first detection elements, and the second detection mechanism is configured using a portion of the plurality of second detection elements. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ the first detecting mechanism is configured using a portion of the plurality of first detecting elements having different height positions in the optical axis direction, the second detecting mechanism is configured using a portion of the plurality of second detecting elements having different height positions in the optical axis direction.

6. The pattern inspection apparatus according to claim 1, wherein the common detecting optical system has an objective lens, the third adjusting mechanism adjusts the positional relationship between the height position of the pattern formation surface of the substrate and the objective lens by moving the substrate or the objective lens, so that the design focal position of the third light beam is in focus.

7. The pattern inspection apparatus according to claim 1, wherein the first detecting optical system has a first collimator lens and a first imaging lens, the first adjusting mechanism moves at least one of the first collimator lens, the first imaging lens, and the first sensor, so that the focal position of the first light beam coincides with the detection surface of the first sensor.

8. The pattern inspection apparatus according to claim 7, wherein the second detecting optical system has a second collimator lens and a second imaging lens, the second adjusting mechanism moves at least one of the second collimator lens, the second imaging lens, and the second sensor, so that the focal position of the second light beam coincides with the detection surface of the second sensor.

9. The pattern inspection apparatus according to claim 1, wherein the control circuit determines which of the first positional relationship, the second positional relationship, and the third positional relationship has the largest amount of change, and controls at least two of the first adjusting mechanism, the second adjusting mechanism, and the third adjusting mechanism in such a manner that the positional relationship having the largest amount of change is adjusted first.

10. The pattern inspection apparatus according to claim 1, wherein further comprising: an illumination slit plate that forms a first illumination slit image and a second illumination slit image that illuminate the first region and the second region of the substrate, the first sensor receives the first light beam reflected from the first region of the substrate, the second sensor receives the second light beam reflected from the second region of the substrate.

11. The pattern inspection apparatus according to claim 4, wherein the first detecting mechanism detects the change in the first positional relationship using data detected by receiving a portion of the first light beam by a portion of the plurality of first detecting elements, the second detecting mechanism detects the change in the second positional relationship using data detected by receiving a portion of the second light beam by a portion of the plurality of second detecting elements.

12. The pattern inspection apparatus according to claim 3, wherein the confocal sensor measures the amount of light at the front focal position and the amount of light at the back focal position of the third light beam, and detects the change in the third positional relationship using the amount of light at the front focal position and the amount of light at the back focal position of the third light beam.

13. The pattern inspection apparatus according to claim 1, wherein The third detection mechanism has a position sensor that detects a height position of a pattern formation surface of the substrate.

14. A pattern inspection method, wherein a first light beam transmitted or reflected by a first region of a substrate on which a pattern is formed and placed on a stage is received by a first sensor, thereby capturing a first optical image of the substrate, a second light beam transmitted or reflected by a second region of the substrate is received by a second sensor at the same timing as the receiving timing of the first sensor, thereby capturing a second optical image of the substrate, a third region of the substrate is illuminated with light for focus adjustment using a common detection optical system, and the first light beam, the second light beam, and a third light beam reflected by the third region of the substrate are guided to a common detection optical path, the first light beam, the second light beam, and the third light beam are separated, the separated first light beam is imaged on the first sensor using a first detection optical system, the separated second light beam is imaged on the second sensor using a second detection optical system, a change in a first positional relationship between a focal point position of the first light beam and the first sensor is detected, a change in a second positional relationship between a focal point position of the second light beam and the second sensor is detected, a change in a third positional relationship between a focal point position of the separated third light beam and a focal point position of the substrate side of the common detection optical system is detected, based on the change in the first positional relationship, the change in the second positional relationship, and the change in the third positional relationship, at least two of a first adjustment mechanism that automatically adjusts the first positional relationship, a second adjustment mechanism that automatically adjusts the second positional relationship, and a third adjustment mechanism that automatically adjusts the third positional relationship are controlled to adjust at least two of the first positional relationship, the second positional relationship, and the third positional relationship.

Images