JP5320936B2 - Inspection condition setting method and inspection apparatus in periodic pattern unevenness inspection apparatus - Google Patents

Description

  The present invention relates to an apparatus and method for inspecting pattern unevenness in an inspection object having a periodic pattern. A periodic pattern refers to an aggregate of patterns having a constant interval. For example, a periodic pattern of stripes in which patterns are arranged at a predetermined pitch, or a pattern of openings is two-dimensionally arranged at a predetermined period. Such a matrix pattern corresponds to this. Examples of the inspection object having a periodic pattern include a photomask used in an exposure process of a photolithography process when manufacturing a semiconductor device, an imaging device, a display device, and the like.

  Conventionally, as a photomask used in a manufacturing process of a semiconductor device, an imaging device, a display device and the like, a photomask that is configured by partially removing a light shielding film such as chromium on a transparent substrate such as glass in a certain pattern is used. Are known.

  Uneven defects in periodic patterns such as photomasks are usually caused by the regular arrangement of fine pitch deviations and positional deviations, and are therefore difficult to find by individual pattern inspection. However, this is a defect recognized for the first time when the periodic pattern is observed in a wide area.

  In the conventional unevenness inspection of periodic patterns, a transmittance image is captured using coaxial transmission illumination or planar illumination, and the normal portion and the unevenness portion are visually recognized by comparing the light intensity in each image. . However, the difference in light intensity between the normal part and the uneven part is not always large, and the contrast of the obtained image is low. For this reason, the contrast difference is improved by devising an intensity difference processing method for an image having a low contrast, and a nonuniformity portion is extracted for inspection (see Patent Document 1).

  However, in the above-described conventional technique, in the imaging of the black matrix unevenness of the lattice-like periodic pattern, particularly the black matrix unevenness having a large opening, the contrast between the normal portion and the uneven portion is not expected to be improved. However, the inspection in the case of an image with a low contrast of the original image has a problem that only an inspection ability lower than the visual sensory inspection method can be achieved.

  On the other hand, due to the miniaturization of semiconductors and the increase in electronic components with fine displays and bright screens, the periodic pattern tends to be miniaturized or the ratio of openings is increased. In the future, a non-uniformity inspection apparatus and method for a periodic pattern having a finer shape and a larger opening will be required. That is, there is a limit in the conventional output with only the intensity (brightness) of light based on the amplitude of light.

  Therefore, for the purpose of providing a periodic pattern unevenness inspection apparatus capable of imaging and detecting a periodic pattern, for example, black matrix unevenness stably and with high accuracy, illumination light is irradiated onto the object to be inspected. For example, an inspection apparatus such as Patent Document 2 for inspecting transmitted diffracted light generated by a pattern has been proposed. In the normal part of the periodic pattern, the shape and pitch of the openings are constant, so that they interfere with each other and generate diffracted light in a certain direction. On the other hand, since the shape and pitch of the opening are irregular in the uneven portion, diffracted light is generated with various intensities in various directions according to the shape and pitch. In this inspection apparatus, a method of detecting a nonuniformity portion from the difference in diffracted light intensity contrast between the normal portion and the nonuniformity portion is adopted. However, in this apparatus, in order to obtain an image satisfying a desired defect inspection sensitivity, it is necessary to set an optimal inspection condition for each type of inspection object. A lot of time is required. In addition, since it includes a sensory test element that inspection accuracy varies among workers, it is not preferable from the viewpoint of standardization of the inspection method.

  By the way, in a periodic pattern, for example, a photomask, the miniaturization of the pattern is rapidly progressing. Particularly, in a photomask for a CCD / CMOS imager, generations are generated at such a momentum that the cell pitch at the time of wafer transfer approaches 1 μm. Progressing.

  On the other hand, with CCD / CMOS imager masks, there is still a high need for unevenness inspection for existing products having a cell pitch of about several tens of μm, and the cell pitch in products to be inspected varies widely. Accordingly, there is a demand for an inspection apparatus having a function capable of automatically setting inspection conditions flexibly for each kind of such a wide variety of inspection objects.

  In addition, for the purpose of providing a defect inspection apparatus capable of easily selecting an appropriate inspection condition, reflectance data at a part having no subject defect measured at a plurality of center wavelengths and incident angles is obtained. A defect inspection apparatus that acquires and sets a center wavelength and an incident angle at the time of capturing an image used for defect detection based on the reflectance data has been proposed (see, for example, Patent Document 3). However, even in this device, the process of determining the center wavelength and the incident angle from the reflectance data largely depends on the operator's senses, and there is a possibility of accuracy problems and variations in inspection accuracy among operators. Still exists.

The known literature is described below.
JP 2002-148210 A JP 2006-208084 A JP 2005-274156 A

  The present invention has been made in view of the above problems, and the object of the present invention is to have a periodic pattern, particularly a cell pitch and pattern directionality as in a photomask for a CCD / CMOS imager. It is an object of the present invention to provide an optimal inspection condition setting method for acquiring an image for accurately discriminating between a normal part and a fluctuating part from the contrast of diffracted light.

In order to solve the above problems, the invention according to claim 1 is directed to inspecting a substrate having a periodic pattern formed on the substrate surface, and irradiating illumination light obliquely at a plurality of irradiation angles to the substrate. An inspection condition setting method in a non-uniformity inspection apparatus that inspects using diffracted light generated by the periodic pattern, the inspection target substrate information input step for inputting information related to the shape of the periodic pattern, and on the substrate surface Positioning step for positioning the substrate in the X-axis and Y-axis directions, which are two orthogonal directions, and positioning the substrate in a rotation direction around a substrate surface normal line orthogonal to the substrate surface, and the inspection target substrate information input step Irradiating light from a light source of a predetermined wavelength from the normal direction of the substrate surface with respect to the periodic pattern based on the information on the periodic pattern input in Diffracted light intensity peak angle calculation step of obtaining a diffracted light angle and a diffracted light order at that time by a theoretical calculation to obtain a maximum value of the diffracted light intensity among the diffracted light that can be generated in the case of diffracted light, and the diffracted light intensity peak angle Based on the diffracted light angle and the diffracted light order obtained in the calculation step, a measurement angle range is determined when measuring the diffracted light intensity by irradiating the periodic pattern with the illumination light at a plurality of irradiation angles. The diffracted light measurement angle range determining step for measuring the diffracted light intensity is performed for the plurality of irradiation angles in the measurement angle range determined in the diffracted light measurement angle range determining step, and for each irradiation angle A diffracted light intensity acquisition step for obtaining a diffracted light intensity profile comprising diffracted light intensity, a diffracted light intensity profile obtained in the diffracted light intensity acquisition step, and the diffracted light intensity peak Diffracted light order diffracted light angles obtained in degrees calculation step, derived based on the illumination light wavelength, the irradiation angle of the illumination light, and inspection condition setting step of setting the inspection conditions including an imaging magnification and illumination light wavelength The diffracted light intensity peak angle calculating step is performed based on Bragg diffraction conditions, and the calculated diffracted light angle relates to diffracted light having a diffracted light order of 20th order or less, The value of the diffracted light angle is at least 10 degrees or more .

According to a second aspect of the present invention, a substrate having a periodic pattern formed on the substrate surface is an inspection target, and illumination light is obliquely irradiated to the substrate at a plurality of irradiation angles, and diffracted light generated by the periodic pattern. An inspection condition setting method in a non-uniformity inspection apparatus for inspecting using a substrate, an inspection target substrate information input step for inputting information relating to the shape of the periodic pattern, and an X axis Y that is two orthogonal directions on the substrate surface A positioning step for positioning the substrate in the axial direction, and a positioning step for positioning the substrate in a rotation direction around a substrate surface normal perpendicular to the substrate surface; and the periodic pattern input in the inspection target substrate information input step Based on the information, the diffracted light generated when light from a light source of a predetermined wavelength is irradiated from the normal direction of the substrate surface to the periodic pattern. A diffracted light intensity peak angle calculating step for obtaining the maximum value of the diffracted light intensity and the diffracted light order at that time by theoretical calculation; and a diffracted light angle obtained in the diffracted light intensity peak angle calculating step. Diffracted light measurement angle range determination for determining the measurement angle range when measuring the diffracted light intensity by irradiating the periodic pattern with a plurality of irradiation angles based on the diffraction light order And measuring the diffracted light intensity for the plurality of irradiation angles in the measurement angle range determined in the diffracted light measurement angle range determining step, and a diffracted light intensity profile comprising the diffracted light intensity for each irradiation angle. Diffracted light intensity acquisition step, diffracted light intensity profile obtained in the diffracted light intensity acquisition step, and diffracted light intensity peak angle obtained in the step An inspection condition setting step for setting an inspection condition including an irradiation angle of the illumination light, an imaging magnification, and an illumination light wavelength, which is derived based on the folding angle, the diffracted light order, and the illumination light wavelength. Is the maximum value at the irradiation angle that is substantially the same as the value of the diffracted light angle calculated in the diffracted light intensity peak angle calculating step among the maximum values of the diffracted light intensity profile obtained in the diffracted light intensity obtaining step. Among them, the irradiation angle when the light intensity value takes the minimum value is set as the inspection condition.

Further, in the invention according to claim 3, the inspection target substrate information input step is a diffraction in a case where illumination light is irradiated at an arbitrary angle in a rotation direction around the normal to the substrate surface with respect to the periodic pattern. acquisition of the light intensity, so that it can be configured for test conditions, wherein the condition input with respect to the angle in the rotational direction of the substrate surface normal rotation is possible, in the unevenness inspection device according to claim 1 or 2 This is an inspection condition setting method.

  The invention according to claim 4 is characterized in that, in the diffracted light measurement angle range determination step, the measurement angle range determined is within a range of at least 10 degrees and not more than 60 degrees. 4. The inspection condition setting method in the unevenness inspection apparatus according to any one of 3 above.

  The diffracted light intensity acquisition step of the invention described in claim 5 is a method in which the diffracted light from the periodic pattern is measured by light intensity measuring means using a photoelectric conversion element, and the light The intensity measuring means has an optical system for extracting only diffracted light perpendicular to the substrate surface from diffracted light generated by the periodic pattern. This is an inspection condition setting method in the unevenness inspection apparatus.

According to a sixth aspect of the present invention, a substrate having a periodic pattern formed on the substrate surface is an inspection target, and illumination light is obliquely irradiated to the substrate at a plurality of irradiation angles, and diffracted light generated by the periodic pattern. A non-uniformity inspection apparatus that inspects using the inspection substrate information input means for inputting information related to the shape of the periodic pattern, and the substrate in the X-axis and Y-axis directions that are two orthogonal directions on the substrate surface And positioning means for positioning the substrate in a rotation direction around a substrate surface normal perpendicular to the substrate surface, and information on the periodic pattern input in the inspection target substrate information input means, Of diffracted light that can be generated when light from a light source of a predetermined wavelength is irradiated from the normal direction of the substrate surface to the periodic pattern, the diffracted light intensity is maximized Based on the diffracted light angle and diffracted light order obtained in the diffracted light intensity peak angle calculating means, the diffracted light intensity peak angle calculating means for obtaining the diffracted light angle and the diffracted light order at that time by theoretical calculation, Diffracted light measurement angle range determining means for determining a measurement angle range when measuring the diffracted light intensity by irradiating the periodic pattern with the illumination light at a plurality of irradiation angles; Diffracted light intensity acquisition means for performing measurement for the plurality of irradiation angles in the measurement angle range determined by the diffracted light measurement angle range determining means, and obtaining a diffracted light intensity profile comprising the diffracted light intensity for each irradiation angle; Diffracted light intensity profile obtained in the diffracted light intensity acquisition means, diffracted light angle and diffracted light order obtained in the diffracted light intensity peak angle calculating means, Inspection condition setting means for setting an inspection condition including an illumination angle of illumination light, an imaging magnification, and an illumination light wavelength, derived based on the bright light wavelength, and the diffracted light intensity peak angle calculation means includes Bragg's The calculation is executed based on the diffraction conditions, and the calculated diffracted light angle relates to diffracted light having a diffracted light order of 20th order or less, and the value of the diffracted light angle is at least 10 degrees or more. And

According to a seventh aspect of the present invention, a substrate having a periodic pattern formed on the substrate surface is an inspection object, and illumination light is obliquely irradiated to the substrate at a plurality of irradiation angles, and diffracted light generated by the periodic pattern a unevenness inspection device for inspecting with the in inspection and target substrate information input means, a two orthogonal directions on the substrate plane X-axis Y-axis direction for inputting information about the shape of the periodic pattern substrate And positioning means for positioning the substrate in a rotation direction around a substrate surface normal perpendicular to the substrate surface, and information on the periodic pattern input in the inspection target substrate information input means, Of diffracted light that can be generated when light from a light source of a predetermined wavelength is irradiated from the normal direction of the substrate surface to the periodic pattern, the diffracted light intensity is maximized Based on the diffracted light angle and diffracted light order obtained in the diffracted light intensity peak angle calculating means, the diffracted light intensity peak angle calculating means for obtaining the diffracted light angle and the diffracted light order at that time by theoretical calculation, Diffracted light measurement angle range determining means for determining a measurement angle range when measuring the diffracted light intensity by irradiating the periodic pattern with the illumination light at a plurality of irradiation angles; Diffracted light intensity acquisition means for performing measurement for the plurality of irradiation angles in the measurement angle range determined by the diffracted light measurement angle range determining means, and obtaining a diffracted light intensity profile comprising the diffracted light intensity for each irradiation angle; Diffracted light intensity profile obtained in the diffracted light intensity acquisition means, diffracted light angle and diffracted light order obtained in the diffracted light intensity peak angle calculating means, Meiko derived based on the wavelength, the irradiation angle of the illumination light, and a test condition setting means for setting the inspection conditions including an imaging magnification and illumination light wavelength, said inspection condition setting means, the diffracted light intensity acquisition Among the maximum values of the diffracted light intensity profile obtained in the process, the light intensity value is among the maximum values at the irradiation angle that approximately matches the value of the diffracted light intensity peak angle calculated in the diffracted light intensity peak angle calculating step. The irradiation angle when taking the smallest maximum value is set as an inspection condition .

  According to the periodic pattern unevenness inspection apparatus and method of the present invention, a periodic pattern, particularly a test object having a wide range of cell pitches and pattern orientations, such as a photomask for a CCD / CMOS imager. Therefore, it is possible to set an optimum inspection condition when acquiring an image for accurately discriminating between a normal part and a fluctuating part from the contrast by diffracted light.

  A first embodiment of an inspection condition setting method in a periodic pattern unevenness inspection apparatus to which the present invention is applied will be described below.

  FIG. 1 is a configuration diagram schematically showing a part of an unevenness inspection apparatus 1 to which a method of a first embodiment according to the present invention is applied. FIG. 1 shows an apparatus configuration example for obtaining transmitted diffracted light. It is desirable that this apparatus be operated in a dark environment where disturbance light and stray light are reduced as much as possible and in a clean environment that prevents foreign matter from adhering to the substrate to be inspected.

As shown in FIG. 1, the apparatus performs positioning of the transmitted illumination unit 10, the XY-θ stage unit 20 capable of positioning and transporting the substrate 60 to be inspected, and the substrate 60 to be inspected. The imaging unit 30 for alignment, the diffracted light intensity measuring unit 40 for acquiring the diffracted light intensity from the substrate 60 to be inspected, and the processing / control unit 100 are configured.
Here, a periodic pattern is formed on the substrate surface of the inspected substrate 60. Here, the substrate surface is a surface located on one side in the thickness direction of the inspected substrate 60.

  The processing / control unit 100 controls the operation of the devices that constitute the transmitted illumination unit 10, the XY-θ stage unit 20, the alignment imaging unit 30, and the diffracted light intensity measurement unit 40, and the alignment imaging unit 30 and The output from the diffracted light intensity measurement unit 40 is input as image information or signal information, and calculation processing is performed. Further, the processing result and the processed image are displayed on the display unit 104.

  In the transmitted illumination unit 10, an arc rail 11 is installed, and an illumination head 12 is provided on the arc rail 11, and the light source 13 guides light using a light guide 14. By driving the illumination head 12 on the arc rail 11, the irradiation angle can be adjusted in the direction perpendicular to the substrate surface of the substrate 60 to be inspected (this drive axis is defined as the φ axis). The illumination head 12 is adjusted so that it can irradiate illumination light to a predetermined position on the XY-θ stage unit 20 at any position on the arc rail 11, and thereby, XY Transmission illumination from various irradiation angles can be performed on the substrate surface of the substrate 60 to be inspected on the −θ stage unit 20.

  The illumination head 12 is provided with a parallel optical system. The light source 13 is provided with a filter changer mechanism, and a plurality of wavelength selection filters can be used. In the present embodiment, a metal halide lamp is used as the light source 13, and a light amount fluctuation range with respect to the operation time is 1% or less and a light amount stability is high.

  FIG. 2 schematically shows the XY-θ stage unit 20. The inspected substrate 60 is placed at a predetermined position of the XY-θ stage unit 20. The inspected substrate 60 mounting portion is characterized by being hollow.

  The XY-θ stage unit 20 functions to translate the substrate 60 to be inspected in the X-axis direction and the Y-axis direction in FIG. 2 and to rotate the substrate 60 to be inspected about a normal to the substrate surface perpendicular to the substrate surface. It has a function of rotating 360 ° in the direction (the axis of rotation center is the θ axis). As a result, the inspected substrate 60 is driven in the X-axis and Y-axis directions according to a preset operation procedure. Further, by rotating the inspected substrate 60 in the plane about the θ axis, it is possible to adjust the illumination irradiation direction in the substrate surface of the inspected substrate 60.

  The alignment imaging unit 30 includes a camera 31, a lens 32, an illumination 33, and an illumination control device 34. Illumination light is radiated to the region including the alignment mark on the inspected substrate 60 in the coaxial epi-illumination format, and the observation image is captured by the camera 31. Note that the illumination control device 34 can turn on / off the illumination and adjust the illumination light intensity, and the actual control operation is performed by the processing / control unit 100. In this embodiment, the camera 31 is an area CCD camera, the lens 32 is a coaxial incident type fixed magnification telecentric lens, and the illumination 33 is a high brightness spot type white LED.

  The diffracted light intensity measurement unit 40 includes a photoelectric sensor 41 and a parallel optical system 42. The photoelectric sensor 41 preferably includes a photoelectric conversion element having spectral sensitivity characteristics in the visible light range.

  In the processing / control unit 100, the information processing unit 101 performs operation management and control of the transmitted illumination unit 10, the XY-θ stage unit 20, the alignment imaging unit 30, and the diffracted light intensity measurement unit 40.

  FIG. 3 is a flow chart illustrating a method according to the first embodiment of the present invention. The method according to the first embodiment of the present invention is performed by a series of steps S1 to S7. Hereinafter, the contents of each step will be described in the order of steps. Note that operation operations such as attachment / detachment of the inspected substrate 60 are omitted from the flow.

The pitch, chip layout, management No. And the like are input to the information processing means 101 (S1). At this stage, the type of the θ axis described above is also input.
The information processing means 101 constitutes inspection target board information input means for inputting information related to the shape of the periodic pattern.
Here, FIG. 4 shows the correspondence relationship between the inspected substrate 60 and θ (in this case, four types of θ = 0 °, 45 °, 90 °, and 135 ° are defined as an example).

An alignment operation for the inspected substrate 60 is performed by adjusting the X, Y, and θ axes and the alignment imaging unit 30 (S2).
That is, positioning in the X-axis and Y-axis directions, which are two directions orthogonal to each other on the substrate surface, and the substrate surface orthogonal to the substrate surface by the XY-θ stage unit 20, the alignment imaging unit 30, and the processing / control unit 100. Positioning means for positioning in the rotational direction around the normal is configured.

Based on the diffraction grating equation shown in Expression (1), an angle φ (m) at which the peak of the diffracted light intensity is obtained from the pitch value input in S1 is calculated for each diffracted light order m (S3).
In this embodiment, all angles φ (m) satisfying 10 ° ≦ φ (m) ≦ 60 ° and m ≦ 20 are calculated. Here, the reason why φ (m) and m are in the above ranges is as follows. When φ (m) is smaller than 10 °, direct light (0th-order diffracted light) from the illumination head 12 may be incident on the diffracted light intensity measuring unit 40, so that the photoelectric sensor 41 is driven by direct light having high light intensity. The 0th order diffracted light does not contribute to the determination of the presence or absence of unevenness of the object to be inspected, and therefore should not be incident as much as possible. Further, when φ (m) is larger than 60 ° or m is larger than 20, the intensity of diffracted light becomes weak, so that the diffracted light intensity profile cannot be said to be useful data for determining the inspection condition. .
For the above reasons, φ (m) and m are in the above ranges.
Further, the calculation according to the equation (1) is performed for each of the illumination light center wavelengths λ when the R, G, and B optical filters are used. Λ = 670 nm when using the R filter, λ = 540 nm when using the G filter, and λ = 435 nm when using the G filter. In this embodiment, a case where a G filter is used will be described. However, since the apparent pitch value corresponding to the light irradiation direction changes according to θ determined in S1, it is necessary to derive the apparent pitch di on each θ axis. When 0 ° ≦ θ ≦ 45 ° and 90 ° ≦ θ ≦ 135 °, it is derived as di = (pitch) / cos θ, and when 45 ° ≦ θ ≦ 90 ° and 135 ° ≦ θ ≦ 180 °, It is derived as di = (pitch) / cos (90 ° −θ). FIG. 5 shows the relationship between the diffracted light order m and the diffraction angle φ (m) when the calculation is performed with di = 15 μm when the G filter is used.

  Of all diffraction angles φ (m) satisfying 10 ° ≦ φ (m) ≦ 60 ° and m ≦ 20 calculated in S3, the minimum angle is φs and the maximum angle is φe, and the diffracted light intensity measurement is performed. The angle range to be implemented is defined as φs ≦ φ (m) ≦ φe (S4). In this embodiment, Δφ (m) = 0.5 °.

  The XY-θ stage unit 20 is driven so that the diffracted light intensity measurement target pattern comes to the center position of the photoelectric sensor 41 (S5).

  Utilizing the diffracted light intensity measurement unit 40 and the transmitted illumination unit 10, constant in the diffracted light measurement angle range φs ≦ φ (m) ≦ φe set in S 4 on the predetermined θ axis set in S 1. The diffracted light intensity at the inspected substrate 60 is measured with a step angle width of (in this embodiment, 0.5 ° increments) to obtain a diffracted light intensity profile (S6).

  The arc rail 11 is driven at a constant step angle within a range of φs ≦ φ (m) ≦ φe, and illumination light is projected onto the substrate 60 to be inspected. At that time, the intensity of diffracted light generated in the periodic pattern on the substrate 60 to be inspected continuously changes. This diffracted light intensity change is acquired as light intensity by the photoelectric sensor 41. At this time, the inspected substrate 60 remains fixed. FIG. 6 shows a schematic diagram of the measurement method in this example, and FIG. 7 shows an example of the diffracted light intensity profile obtained by the measurement.

  In the diffracted light intensity profile acquired in S6, paying attention to the maximum value corresponding to the diffraction angle φ (m) obtained in S3, the value of the angle φ (m) at the maximum value with the smallest light intensity value. Is determined as the inspection angle φI. After adjusting the illumination light quantity so as to ensure a desired light quantity value at the determined illumination angle, inspection conditions are set (S7). FIG. 8 schematically shows a method for setting conditions from the diffracted light intensity profile and the calculated diffraction angle φ (m).

  The parameter called evaluation value C shown in FIG. 8 is a value obtained by taking the contrast ratio of the luminance values in the normal part and the fluctuation part in the actually detected mura defect image. It is shown that the value of C varies depending on the illumination angle, and the value is the largest at the inspection angle φI. That is, it is shown that the contrast between the normal part and the fluctuation part can be best identified at this illumination angle.

The flow from S3 to S7 is repeated for the θ axis set in S1.
After the inspection conditions are determined for all the θ axes, the process proceeds to an actual inspection operation.
The flow from S3 to S7 is executed by the processing / control unit 100.
That is, when the processing / control unit 100 irradiates light from a light source having a predetermined wavelength λ from the normal direction of the substrate surface based on the information related to the periodic pattern input in S1. Of the diffracted light that can be generated, a diffracted light intensity peak angle calculating means for obtaining the diffracted light angle at which the maximum value of the diffracted light intensity is obtained and the diffracted light order at that time is obtained by theoretical calculation (S3).
Further, the processing / control unit 100 irradiates the periodic pattern with illumination light at a plurality of irradiation angles based on the diffracted light angle and the diffracted light order obtained in S3, and measures the diffracted light intensity. The diffracted light measurement angle range determining means for determining the measurement angle range is also configured (S4).
In addition, the processing / control unit 100 measures the diffracted light intensity for a plurality of irradiation angles in the measurement angle range determined in S4, and obtains a diffracted light intensity profile including the diffracted light intensity for each irradiation angle. It also constitutes an intensity acquisition means (S6).
In addition, the processing / control unit 100 determines the illumination light irradiation angle derived based on the diffracted light intensity profile obtained in S6, the diffracted light angle and the diffracted light order obtained in S3, and the illumination light wavelength, The inspection condition setting means for setting the inspection condition including the imaging magnification and the illumination light wavelength is also configured (S7).

  In the method of the first embodiment according to the present invention, when setting the inspection conditions, it is conventionally necessary to change the inspection conditions until the desired inspection sensitivity is obtained, and to repeat the inspection execution and the inspection result confirmation. Therefore, it is possible to reduce labor and tact spent on setting inspection conditions. In addition, by using a quantitative method, it is possible to eliminate variations in inspection accuracy among workers.

  Next, a method according to the second embodiment of the present invention will be described. The schematic apparatus configuration of the second embodiment according to the present invention is the same as that of FIG. 1, and the method according to the second embodiment of the present invention is similarly performed according to the flowchart shown in FIG. However, in the method of the second embodiment according to the present invention, a line sensor camera is used as the photoelectric sensor 41. In the method according to the second embodiment of the present invention, the camera 41 uses a 4096-pixel line sensor camera, but when a constant luminance value cannot be secured even using the camera exposure time adjustment function, A TDI line sensor camera may be used. Further, by providing a plurality of cameras having different performances and a camera switching mechanism, it may be possible to select an optimal one for each measurement by switching the camera used. Further, the lighting head 12 may be a line type lighting head.

  For the parallel optical system 42, an electric zoom lens with a variable optical magnification or a plurality of telecentric lenses for a single-line sensor equipped with a lens switching mechanism such as a turret or a revolver is used. At this time, an automatic aperture adjustment function may be provided. Although the imaging magnification depends on the pitch of the periodic pattern on the substrate 60 to be inspected, it is desirable that the imaging magnification is secured from a low magnification range of about 0.2 times to a high magnification range of about 3 times. In the method according to the second embodiment of the present invention, measurement was performed using a telecentric lens for a line sensor having a lens magnification of 1.4 times.

  A method according to the second embodiment of the present invention will be described based on the flow shown in FIG. Note that steps S1 to S4 are omitted because they are the same as the method of the first embodiment according to the present invention.

  The XY-θ stage unit 20 is driven so that the diffracted light intensity measurement target pattern comes to the center position of the line sensor camera that is the photoelectric sensor 41 (S5).

  Utilizing the diffracted light intensity measurement unit 40 and the transmitted illumination unit 10, constant in the diffracted light measurement angle range φs ≦ φ (m) ≦ φe set in S 4 on the predetermined θ axis set in S 1. The diffracted light intensity at the substrate 60 to be inspected is measured with a step angle width (in this example, 0.5 ° increments) to obtain a diffracted light intensity profile (S6).

  The arc rail 11 is driven at a constant step angle within a range of φs ≦ φ (m) ≦ φe, and illumination light is projected onto the substrate 60 to be inspected. At that time, the intensity of diffracted light generated in the periodic pattern on the substrate 60 to be inspected changes continuously. This diffracted light intensity change is acquired as luminance information for 1 LINE by the line sensor camera used as the photoelectric sensor 41. As the brightness value acquired at this time, the average value of the brightness values acquired with the number of pixels for 1 LINE (4096 pixels in the method according to the present embodiment) is used, but the brightness value acquired with the number of pixels for 1 LINE is used. A maximum value may be used. FIG. 9 shows an example of a diffracted light intensity profile acquired using a line sensor camera.

  In the diffracted light intensity profile acquired in S6, paying attention to the maximum value corresponding to the diffraction angle φ (m) obtained in S3, the value of the angle φ (m) at the maximum value with the smallest light intensity value. Is determined as the inspection angle φI. After adjusting the illumination light quantity so as to ensure a desired light quantity value at the determined illumination angle, inspection conditions are set (S7).

  Also in the method of the second embodiment according to the present invention, the flow from S3 to S7 is repeated for the θ axis set in S1. After the inspection conditions are determined for all the θ axes, a line sensor camera is used as an inspection imaging unit, and the process proceeds to an actual inspection operation.

  In the method of the second embodiment according to the present invention, since a line sensor camera is used as the photoelectric sensor 41, the inspection conditions set in the method of the second embodiment according to the present invention are utilized to perform actual inspection imaging. The line sensor camera of the photoelectric sensor 41 can also be used as an imaging unit for the image acquisition operation by the above. That is, the diffracted light intensity measurement unit 40 and the inspection imaging unit can be shared, which can contribute to cost reduction by reducing the mechanism unit and the equipment.

  As described above, according to the method of the embodiment of the present invention, it is possible to reduce labor for setting inspection conditions in an inspection apparatus for a product having a periodic pattern such as a photomask or a black matrix, and with high accuracy. The optimal illumination angle for defect inspection can be set based on theory. In addition, it is possible to suppress variations in inspection accuracy among workers.

It is the schematic diagram which showed schematically a part of nonuniformity inspection apparatus structure of the periodic pattern which concerns on this invention. FIG. 3 is a schematic diagram of an XY-θ stage unit 20 in the periodic pattern unevenness inspection apparatus according to the present invention. It is a flowchart figure which shows the method of 1st, 2nd embodiment which concerns on this invention. It is a figure which shows the correspondence of the to-be-inspected board | substrate 60 and the light projection direction (theta) axis | shaft in the method of 1st, 2nd embodiment which concerns on this invention. It is the figure which showed the example of calculation by Formula (1) in the method of 1st, 2nd embodiment which concerns on this invention. It is a schematic diagram of the example of a diffracted light intensity profile acquisition means in the method of 1st, 2nd embodiment which concerns on this invention. It is an example of diffracted light intensity profile acquisition in the methods of the first and second embodiments according to the present invention. It is the schematic diagram showing the determination method of the test | inspection angle (phi) I in the method of 1st, 2nd embodiment which concerns on this invention. It is an example of diffracted light intensity profile acquisition in the method of the second embodiment according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Transmitting illumination part 11 Arc rail 12 Illumination head 13 Light source 14 Light guide 20 XY-theta stage part 30 Imaging unit 31 Camera 32 Lens 33 Illumination 34 Illumination control device 40 Diffracted light intensity measurement part 41 Photoelectric sensor 42 Parallel optics System 60 Inspected substrate 100 Processing / control unit 101 Information processing means 102 Signal input device 103 Signal input device 104 Display means 105 Interpersonal operation means

Claims (7)

Inspection in a non-uniformity inspection apparatus that inspects a substrate having a periodic pattern formed on the substrate surface, irradiates the substrate obliquely with illumination light at a plurality of irradiation angles, and inspects using diffracted light generated by the periodic pattern A condition setting method,
An inspection target substrate information input step for inputting information on the shape of the periodic pattern;
A positioning step for positioning the substrate in two orthogonal positioning of the substrate in the X-axis Y-axis direction is a direction, and the rotation direction of the substrate surface normal rotation perpendicular to the substrate surface on the substrate surface,
Occurs when light from a light source of a predetermined wavelength is irradiated from the normal direction of the substrate surface to the periodic pattern based on information on the periodic pattern input in the inspection target substrate information input step. Diffracted light intensity peak angle calculation step of obtaining the diffracted light angle and the diffracted light order at that time from the theoretical calculation among the diffracted light that can be obtained,
Based on the diffracted light angle and the diffracted light order obtained in the diffracted light intensity peak angle calculating step, the diffracted light intensity is measured by irradiating the periodic pattern with the illumination light at a plurality of irradiation angles. Diffracted light measurement angle range determining step for determining the measurement angle range;
The diffracted light intensity is measured for the plurality of irradiation angles in the measurement angle range determined in the diffracted light measurement angle range determination step, and diffraction is obtained to obtain a diffracted light intensity profile composed of the diffracted light intensity for each irradiation angle. A light intensity acquisition step;
Based on the diffracted light intensity profile obtained in the diffracted light intensity acquisition step, the diffracted light angle obtained in the diffracted light intensity peak angle calculating step, the diffracted light order, and the illumination light wavelength, the illumination light is derived. Including an inspection condition setting step for setting an inspection condition including an irradiation angle, an imaging magnification, and an illumination light wavelength ,
In the diffracted light intensity peak angle calculating step, calculation is performed based on Bragg diffraction conditions, and the calculated diffracted light angle relates to diffracted light having a diffracted light order of 20th or less. The value of is at least 10 degrees,
An inspection condition setting method in a non- uniformity inspection apparatus.   Inspection in a non-uniformity inspection apparatus that inspects a substrate having a periodic pattern formed on the substrate surface, irradiates the substrate obliquely with illumination light at a plurality of irradiation angles, and inspects using diffracted light generated by the periodic pattern A condition setting method,
  An inspection target substrate information input step for inputting information on the shape of the periodic pattern;
  A positioning step for positioning the substrate in the X-axis and Y-axis directions, which are two orthogonal directions on the substrate surface, and for positioning the substrate in a rotation direction about a substrate surface normal perpendicular to the substrate surface;
  Occurs when light from a light source of a predetermined wavelength is irradiated from the normal direction of the substrate surface to the periodic pattern based on information on the periodic pattern input in the inspection target substrate information input step. Diffracted light intensity peak angle calculation step of obtaining the diffracted light angle and the diffracted light order at that time from the theoretical calculation among the diffracted light that can be obtained,
  Based on the diffracted light angle and the diffracted light order obtained in the diffracted light intensity peak angle calculating step, the diffracted light intensity is measured by irradiating the periodic pattern with the illumination light at a plurality of irradiation angles. Diffracted light measurement angle range determining step for determining the measurement angle range;
  The diffracted light intensity is measured for the plurality of irradiation angles in the measurement angle range determined in the diffracted light measurement angle range determination step, and diffraction is obtained to obtain a diffracted light intensity profile composed of the diffracted light intensity for each irradiation angle. A light intensity acquisition step;
  Based on the diffracted light intensity profile obtained in the diffracted light intensity acquisition step, the diffracted light angle obtained in the diffracted light intensity peak angle calculating step, the diffracted light order, and the illumination light wavelength, the illumination light is derived. Including an inspection condition setting step for setting an inspection condition including an irradiation angle, an imaging magnification, and an illumination light wavelength,
  The inspection condition setting step includes an irradiation that substantially matches the value of the diffracted light angle calculated in the diffracted light intensity peak angle calculating step among the maximum values of the diffracted light intensity profile obtained in the diffracted light intensity acquiring step. Set the irradiation angle as the inspection condition when the light intensity value is the smallest among the maximum values in the angle,
  It is characterized by
  Inspection condition setting method in unevenness inspection apparatus. In the inspection target substrate information input step, the diffracted light intensity is obtained when the illumination light is irradiated at an arbitrary angle in the rotation direction around the substrate surface normal to the periodic pattern, and the inspection condition is set. as can, characterized in that it is a possible condition input with respect to the angle in the rotational direction of the substrate plane normal direction, the inspection condition setting method in the unevenness inspection device according to claim 1 or 2.   The unevenness inspection apparatus according to claim 1, wherein the measurement angle range determined in the diffracted light measurement angle range determination step is within a range of at least 10 degrees and not more than 60 degrees. Inspection condition setting method.   In the diffracted light intensity acquisition step, the measurement of diffracted light from the periodic pattern is performed by light intensity measuring means using a photoelectric conversion element, and the light intensity measuring means is measured by the periodic pattern. The inspection condition setting method in the unevenness inspection apparatus according to claim 1, further comprising an optical system that extracts only diffracted light perpendicular to the substrate surface from the generated diffracted light.   A non-uniformity inspection apparatus that inspects a substrate having a periodic pattern formed on the substrate surface, irradiates the substrate obliquely with illumination light at a plurality of irradiation angles, and inspects using diffracted light generated by the periodic pattern. And
  Inspection target substrate information input means for inputting information on the shape of the periodic pattern;
  Positioning means for positioning the substrate in the X-axis and Y-axis directions, which are two orthogonal directions on the substrate surface, and positioning the substrate in a rotational direction around a normal to the substrate surface orthogonal to the substrate surface;
  Occurs when light from a light source of a predetermined wavelength is irradiated from the normal direction of the substrate surface to the periodic pattern based on information on the periodic pattern input by the inspection target substrate information input means. Diffracted light intensity peak angle calculating means for obtaining a diffracted light angle and a diffracted light order at that time by a theoretical calculation among the diffracted light,
  Based on the diffracted light angle and the diffracted light order obtained by the diffracted light intensity peak angle calculating means, the diffracted light intensity is measured by irradiating the periodic pattern with the illumination light at a plurality of irradiation angles. Diffracted light measurement angle range determining means for determining the measurement angle range;
  The diffracted light intensity is measured for the plurality of irradiation angles in the measurement angle range determined by the diffracted light measurement angle range determining means, and a diffraction is obtained to obtain a diffracted light intensity profile composed of the diffracted light intensity for each irradiation angle Light intensity acquisition means;
  The illumination light derived from the diffracted light intensity profile obtained by the diffracted light intensity acquisition means, the diffracted light angle obtained by the diffracted light intensity peak angle calculating means, the diffracted light order, and the illumination light wavelength. An inspection condition setting means for setting an inspection condition including an irradiation angle, an imaging magnification, and an illumination light wavelength;
  The diffracted light intensity peak angle calculating means performs calculation based on Bragg diffraction conditions, and the calculated diffracted light angle relates to diffracted light having a diffracted light order of 20th or less. The value of is at least 10 degrees,
  An unevenness inspection apparatus characterized by that. A non-uniformity inspection apparatus that inspects a substrate having a periodic pattern formed on the substrate surface, irradiates the substrate obliquely with illumination light at a plurality of irradiation angles, and inspects using diffracted light generated by the periodic pattern. And
Inspection target substrate information input means for inputting information on the shape of the periodic pattern;
And positioning means for positioning the substrate in two directions perpendicular to the a X-axis positioning of the substrate in the Y-axis direction, and rotational direction of the substrate surface normal rotation perpendicular to the substrate surface on the substrate surface,
Occurs when light from a light source of a predetermined wavelength is irradiated from the normal direction of the substrate surface to the periodic pattern based on information on the periodic pattern input by the inspection target substrate information input means. Diffracted light intensity peak angle calculating means for obtaining a diffracted light angle and a diffracted light order at that time by a theoretical calculation among the diffracted light,
Based on the diffracted light angle and the diffracted light order obtained by the diffracted light intensity peak angle calculating means, the diffracted light intensity is measured by irradiating the periodic pattern with the illumination light at a plurality of irradiation angles. Diffracted light measurement angle range determining means for determining the measurement angle range;
The diffracted light intensity is measured for the plurality of irradiation angles in the measurement angle range determined by the diffracted light measurement angle range determining means, and a diffraction is obtained to obtain a diffracted light intensity profile composed of the diffracted light intensity for each irradiation angle. Light intensity acquisition means;
The illumination light derived from the diffracted light intensity profile obtained by the diffracted light intensity acquisition means, the diffracted light angle obtained by the diffracted light intensity peak angle calculating means, the diffracted light order, and the illumination light wavelength. An inspection condition setting means for setting an inspection condition including an irradiation angle, an imaging magnification, and an illumination light wavelength ;
The inspection condition setting means is an irradiation that substantially matches the value of the diffracted light angle calculated in the diffracted light intensity peak angle calculating step among the maximum values of the diffracted light intensity profile obtained in the diffracted light intensity obtaining step. Set the irradiation angle as the inspection condition when the light intensity value is the smallest among the maximum values in the angle,
An unevenness inspection apparatus characterized by that .

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