JP2006313143A - Irregularity inspection device and method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately detect film thickness irregularity, concerning a technology for inspecting the film thickness irregularity of a film formed on an object. <P>SOLUTION: This irregularity inspection device 1 is equipped with a stage 2 for holding a substrate 9, a light emission part 3 for emitting linear light toward the upper surface 91 where a film 92 of the substrate 9 is formed, a light reception part 4 for receiving reflected light from the substrate 9, a wavelength band switching mechanism 5 for switching the wavelength band of light received by the light reception part 4, a polarizer 6 arranged on an optical path from the substrate 9 to the wavelength band switching mechanism 5 and transmitting selectively S-polarized light in reflected light from the film 92, a moving mechanism 21 for moving the stage 2, and an inspection part 7 for inspecting the film thickness irregularity based on an intensity distribution of the received light. Since fluctuation of the reflectivity to the S-polarized light is larger, compared with fluctuation of the reflectivity to non-polarized light or P-polarized light, the film thickness irregularity can be detected accurately by improving sensitivity to the film thickness irregularity of a line sensor 41, by changing the light received by the light reception part 4 into the S-polarized light by the polarizer 6 in the irregularity inspection device 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for inspecting film thickness unevenness of a film formed on an object.

  Conventionally, when inspecting a thin film such as a resist film formed on a main surface of a glass substrate or a semiconductor substrate (hereinafter simply referred to as “substrate”) for a display device, the thin film is irradiated with light from a light source. The film thickness unevenness is inspected by utilizing the light interference in the reflected light or transmitted light from the thin film.

  In such a non-uniformity inspection, when a monochromatic light source such as a sodium lamp is used, sufficient sensitivity cannot be obtained depending on the thickness and refractive index of the thin film (that is, interference fringes due to optical interference cannot be clearly shown). Sometimes. Therefore, in visual inspection, unevenness detection is reliably performed by changing the incident angle of light by tilting the substrate and clarifying the interference fringes. Moreover, although light with a plurality of wavelengths is simultaneously irradiated onto the substrate, interference fringes corresponding to the respective wavelengths appear at the same time, so that the sensitivity as a whole may be lowered.

In Patent Document 1, in a surface defect inspection apparatus that performs a defect inspection on the surface of an object, one of a plurality of narrowband filters that limit the wavelength band of reflected light from the object is a thin film on the surface of the object. A technique for inspecting in an appropriate wavelength band by inserting the optical path in accordance with the characteristics (material, refractive index, film thickness, reflectance, etc.) is disclosed. Also disclosed is a technique for changing the angle of the illumination unit that irradiates light to the subject (that is, the incident angle of illumination light to the subject) in accordance with the characteristics of the thin film.
JP 2002-267416 A

  By the way, in the surface defect inspection apparatus of Patent Document 1, the sensitivity of unevenness detection can be improved by switching the narrow band filter or changing the angle of the illumination unit with respect to the subject. Therefore, further improvement in sensitivity is required.

  The present invention has been made in view of the above problems, and an object thereof is to detect film thickness unevenness with high accuracy.

  The invention according to claim 1 is a non-uniformity inspection apparatus for inspecting film thickness nonuniformity of a film formed on a substrate, wherein the holding unit holds a substrate on which a light transmissive film is formed on a main surface. And a light emitting unit that emits light that is incident on the film at an angle, and receives light in a specific wavelength band after being reflected by the film, and receives the light in the specific wavelength band from the film. A sensor that acquires a light intensity distribution; and a polarizer that is disposed on an optical path from the light emitting unit to the sensor and selectively transmits S-polarized light to the film.

  A second aspect of the present invention is the unevenness inspection apparatus according to the first aspect, further comprising wavelength band switching means for switching the specific wavelength band among a plurality of different wavelength bands.

  A third aspect of the present invention is the unevenness inspection apparatus according to the second aspect, wherein the light emitting unit emits light including light of a plurality of wavelength bands, and the wavelength band switching unit includes the plurality of wavelength band switching units. A plurality of optical filters that selectively transmit light in a wavelength band, and one optical filter arranged on the optical path among the plurality of optical filters is switched to another optical filter to change the specific wavelength band. An optical filter switching mechanism to be changed.

  A fourth aspect of the present invention is the unevenness inspection apparatus according to any one of the first to third aspects, wherein the polarizer is disposed between the substrate and the sensor.

  A fifth aspect of the invention is the unevenness inspection apparatus according to the fourth aspect of the invention, which is arranged on an optical path from the substrate to the sensor and collects light of the specific wavelength band toward the sensor. A light collecting lens is further provided, and the polarizer is disposed between the light collecting lens and the sensor.

  A sixth aspect of the present invention is the unevenness inspection apparatus according to any one of the first to third aspects, wherein the polarizer is disposed between the light emitting portion and the substrate.

  A seventh aspect of the invention is the unevenness inspection apparatus according to the sixth aspect of the invention, which is arranged on an optical path from the substrate to the sensor and collects light of the specific wavelength band toward the sensor. A light collecting lens is further provided.

  The invention according to claim 8 is the unevenness inspection apparatus according to any one of claims 1 to 7, wherein the holding unit is arranged in the predetermined movement direction along the main surface of the substrate, and the light emitting unit and the light emitting unit. The light emitting unit further includes a moving mechanism that moves relative to the sensor, and the light emitting unit converts the light from the light source and linear light that extends along the main surface and perpendicular to the moving direction. And an illumination optical system that guides the film to the film, and the sensor repeats the intensity distribution of the light in the specific wavelength band from the irradiation region of the linear light on the substrate during the movement of the holding unit. It is a line sensor to acquire.

  The invention according to claim 9 is a non-uniformity inspection method for inspecting non-uniformity in film thickness of a film formed on the substrate, wherein the film of the substrate having a light-transmitting film formed on the main surface is used. A step of emitting incident light that is inclined, and light of a specific wavelength band after being reflected by the film, and before or after being reflected by the film, S-polarized light with respect to the film Receiving light that has passed through a polarizer that selectively transmits light, and obtaining an intensity distribution of light in the specific wavelength band from the film.

  In the present invention, film thickness unevenness can be detected with high accuracy.

  FIG. 1 is a diagram showing a configuration of an unevenness inspection apparatus 1 according to the first embodiment of the present invention. The unevenness inspection apparatus 1 includes a resist film (hereinafter referred to as a pattern forming resist film) formed on one main surface 91 of a glass substrate (hereinafter simply referred to as “substrate”) 9 used in a display device such as a liquid crystal display device. This is an apparatus for inspecting the film thickness unevenness of 92. The film 92 on the substrate 9 is formed by applying a resist solution on the main surface 91 of the substrate 9.

  As shown in FIG. 1, the unevenness inspection apparatus 1 includes a substrate 9 on which a film 92 is formed on a main surface 91 (hereinafter referred to as “upper surface 91”), with the upper surface 91 on the upper side (the (+ Z) side in FIG. 1. ) Toward the film 92 on the upper surface 91 of the substrate 9 held by the stage 2, and the film 92 emitted from the light emitting unit 3. The light receiving unit 4 that receives the light after being reflected by the light receiving unit 4, the wavelength band switching mechanism 5 that is arranged between the substrate 9 and the light receiving unit 4 and switches the wavelength band of the light received by the light receiving unit 4, the substrate 9 To the wavelength band switching mechanism 5 and the polarizer 6 that selectively transmits S-polarized light out of the reflected light from the film 92, the stage 2 through the light emitting unit 3, the light receiving unit 4, and the wavelength band Light is received by the light receiving unit 4 and the moving mechanism 21 that moves relative to the switching mechanism 5 and the polarizer 6 Inspection unit 7 for inspecting the thickness irregularity of the film 92 based on the intensity distribution of the (corresponding to the region of the upper surface 91 distribution), as well as a control unit 8 for controlling these configurations.

  The (+ Z) side surface of the stage 2 is preferably black matte. The moving mechanism 21 has a configuration in which a ball screw (not shown) is connected to a motor 211, and the stage 211 moves along the upper surface 91 of the substrate 9 along the guide 212 by rotating the motor 211 in FIG. Move in the direction.

  The light emitting section 3 extends in the Y direction in FIG. 1 perpendicular to the movement direction of the halogen lamp 31 and the stage 2 that are white light (that is, light including light in all wavelength bands in the visible region). A cylindrical quartz rod 32 and a cylindrical lens 33 extending in the Y direction are provided. In the light emitting part 3, a halogen lamp 31 is attached to the end on the (+ Y) side of the quartz rod 32, and the light incident on the quartz rod 32 from the halogen lamp 31 is linear light extending in the Y direction (that is, The light beam cross-section is converted to light that is long in the Y direction), is emitted from the side surface of the quartz rod 32, and is guided to the upper surface 91 of the substrate 9 through the cylindrical lens 33. In other words, the quartz rod 32 and the cylindrical lens 33 convert the light from the halogen lamp 31 into linear light along the upper surface 91 of the stage 2 and perpendicular to the moving direction to convert the film 92 on the upper surface 91 of the substrate 9. It is an illumination optical system that leads to

  In FIG. 1, the optical path from the light emitting part 3 to the substrate 9 is indicated by a one-dot chain line (the same applies to the optical path from the substrate 9 to the light receiving part 4). A part of the light emitted from the light emitting portion 3 and incident on the film 92 on the upper surface 91 of the substrate 9 with an inclination (that is, at an incident angle larger than 0 °) is on the upper surface 91 of the substrate 9. Is reflected on the upper surface of the film 92 on the (+ Z) side. The film 92 is light transmissive to the light from the light emitting part 3, and the light that has not been reflected by the upper surface of the film 92 out of the light from the light emitting part 3 passes through the film 92. Reflected by the upper surface 91 of the substrate 9 (that is, the lower surface of the film 92). In the unevenness inspection apparatus 1, interference light (hereinafter simply referred to as “reflected light”) between the light reflected by the upper surface of the film 92 and the light reflected by the upper surface 91 of the substrate 9 is a wavelength band. The light enters the light receiving unit 4 via the switching mechanism 5.

  The wavelength band switching mechanism 5 is a disk-like shape that holds a plurality of optical filters (for example, interference filters having a half-value width of 10 nm) 51 that selectively transmit light of a plurality of different narrow wavelength bands, respectively, and a plurality of optical filters 51. And a filter rotation motor 53 that is attached to the center of the filter wheel 52 and rotates the filter wheel 52. The filter wheel 52 is arranged so that the normal direction thereof is parallel to the optical path from the substrate 9 to the light receiving unit 4.

  FIG. 2 is a view of the wavelength band switching mechanism 5 as viewed from the substrate 9 side along the direction perpendicular to the filter wheel 52. As shown in FIG. 2, the filter wheel 52 has six circular openings 521 formed at equal intervals in the circumferential direction, and five of these openings 521 have five types of optical filters having different transmission wavelength bands. 51 is attached.

  In the wavelength band switching mechanism 5 shown in FIG. 1, the filter wheel 52 is rotated by the filter rotation motor 53 controlled by the control unit 8, and the film 92 to be inspected among the five optical filters 51 (see FIG. 2). Any one optical filter 51 (hereinafter, referred to as “selected optical filter 51a” to be distinguished from other optical filters 51) is selected in accordance with the film thickness, refractive index, and the like, and the substrate 9 receives the light receiving unit 4 from the substrate 9. It is arranged on the optical path to reach. Thereby, among the reflected light from the substrate 9 (that is, reflected light of white light including light of five transmission wavelength bands corresponding to the five optical filters 51), it corresponds to the selected optical filter 51a arranged on the optical path. Only light in a specific wavelength band (hereinafter referred to as “selected wavelength band”) is transmitted through the selective optical filter 51 a and guided to the light receiving unit 4.

  When the filter wheel 52 is rotated by the filter rotation motor 53, the selected optical filter 51 a disposed on the optical path from the light emitting unit 3 to the light receiving unit 4 among the plurality of optical filters 51 is switched to another optical filter 51. The wavelength band of light received by the light receiving unit 4 (that is, the selected wavelength band) is changed. Thus, the filter rotation motor 53 and the filter wheel 52 serve as an optical filter switching mechanism.

  The light receiving unit 4 includes a line sensor 41 in which a plurality of light receiving elements CCD (Charge Coupled Device) are linearly arranged in the Y direction, and an optical path from the substrate 9 to the line sensor 41. A condensing lens 42 is provided between the wavelength band switching mechanism 5 and the selection optical filter 51a. The condenser lens 42 is reflected by a film 92 in a linear irradiation region (hereinafter referred to as “linear irradiation region”) that is emitted from the light emitting unit 3 and extends in the Y direction on the upper surface 91 of the substrate 9. Of the subsequent linear light, the light in the selected wavelength band that has passed through the selection optical filter 51 a is condensed toward the line sensor 41. The line sensor 41 receives the light in the selected wavelength band that is condensed and imaged by the condenser lens 42, and calculates the intensity distribution of the received light (that is, the distribution in the Y direction of the output value from each CCD). Obtain and output to the inspection unit 7. In the unevenness inspection apparatus 1, the intensity distribution of the reflected light from the film 92 formed on the upper surface 91 of the substrate 9 is repeatedly acquired by the line sensor 41 during the movement of the substrate 9 and the stage 2.

  The inspection unit 7 receives the output from the line sensor 41 and generates a two-dimensional image of the upper surface 91 of the substrate 9, and the value of each pixel of the two-dimensional image generated by the image generation unit 71. A non-uniformity detection unit 72 that detects film thickness non-uniformity of the film 92 is provided.

  Next, the flow of inspection of film thickness unevenness by the unevenness inspection apparatus 1 will be described. 3 and 4 are diagrams showing a flow of inspection by the unevenness inspection apparatus 1. When the film thickness unevenness of the film 92 on the upper surface 91 of the substrate 9 is inspected by the unevenness inspection apparatus 1, first, the substrate 9 is held on the stage 2 positioned at the inspection start position indicated by the solid line in FIG. After that, the movement of the substrate 9 and the stage 2 in the (+ X) direction is started (step S11). Subsequently, the linear light emitted from the light emitting unit 3 and incident on the upper surface 91 of the substrate 9 at an incident angle of 60 ° is irradiated to the linear irradiation region on the upper surface 91 of the substrate 9 (step S12). The linear irradiation area moves relative to the substrate 9.

  The light from the light emitting portion 3 is reflected by the upper surface 91 of the substrate 9 and passes through the polarizer 6 so that only S-polarized light is extracted. Then, after passing through the selection optical filter 51a of the wavelength band switching mechanism 5, only light in a specific wavelength band (for example, the center wavelength is 550 nm and the half width is 10 nm) is extracted from the S-polarized light, and then the light receiving unit 4 leads to. In the light receiving unit 4, the S-polarized light in the selected wavelength band after reflection on the upper surface 91 of the substrate 9 is imaged while being condensed toward the line sensor 41 by the condenser lens 42 and received by the line sensor 41 (step). S13) Of the reflected light from the linear irradiation region on the substrate 9, the intensity distribution in the selected wavelength band of S-polarized light is acquired (step S14). The output value from each CCD of the line sensor 41 is sent to the image generation unit 71 of the inspection unit 7.

  In the unevenness inspection apparatus 1, whether or not the substrate 9 and the stage 2 have moved to the inspection end position indicated by a two-dot chain line in FIG. S15) If not moved to the inspection end position, the process returns to step S13 to receive the S-polarized light in the selected wavelength band of the reflected light and the intensity distribution of the S-polarized light in the selected wavelength band in the linear irradiation region. (Steps S13 and S14) are repeated. In the unevenness inspection apparatus 1, while the stage 2 moves in the (+ X) direction, the operations in steps S <b> 13 to S <b> 15 are repeated and the intensity distribution of the reflected light from the linear irradiation region on the substrate 9 is repeatedly acquired. Thus, the intensity distribution in the selected wavelength band of the S-polarized light out of the reflected light from the upper surface 91 is obtained for the entire substrate 9.

  When the substrate 9 and the stage 2 move to the inspection end position (step S15), the movement of the substrate 9 and the stage 2 by the moving mechanism 21 is stopped, and the illumination light irradiation is also stopped (step S16). In the image generation unit 71 of the inspection unit 7, image processing for emphasizing the difference in luminance value caused by the change in film thickness with respect to the intensity distribution in the selected wavelength band of the reflected light from the upper surface 91 acquired by the light receiving unit 4 (For example, a two-dimensional image showing the intensity distribution on the upper surface 91 (hereinafter referred to as “original image”) is smoothed by a median filter to obtain a smoothed image, and the value of each pixel of the original image is determined. By dividing by the value of the corresponding pixel in the smoothed image, a process such as removing a luminance value variation over a wider range than that caused by the film thickness variation) is performed, so that the emphasized film thickness variation is A two-dimensional image (hereinafter referred to as “enhanced image”) of the upper surface 91 expressed as a change in pixel value is generated (step S21).

  The generated emphasized image is displayed on a display device such as a display as necessary, and the unevenness detection unit 72 of the inspection unit 7 detects film thickness unevenness based on the emphasized image (step S22).

  FIG. 5 is a diagram showing the relationship between the film thickness of the film 92 formed on the upper surface 91 of the substrate 9 and the reflectance. A line 101 in FIG. 5 indicates the reflectance under the same conditions as the unevenness inspection apparatus 1 according to the present embodiment (that is, the reflectance with respect to S-polarized light). A line 102 represents the reflectance under the same conditions as the apparatus in which the polarizer 6 is omitted from the unevenness inspection apparatus 1 (that is, the reflectance with respect to unpolarized light (hereinafter referred to as “non-polarized light”)). The line 103 indicates the reflectance under the same conditions as the apparatus provided with other polarizers that selectively transmit only the P-polarized light instead of the polarizer 6 of the unevenness inspection apparatus 1 (that is, with respect to the P-polarized light). Reflectivity). Lines 101 to 103 indicate the reflectance with respect to light having a wavelength of 550 nm, and the relationship between the film thickness and the reflectance changes when the wavelength is changed.

  As shown in FIG. 5, when the film thickness of the film 92 is different, the reflectance of the film 92 is also different, so that the intensity of the reflected light received by the light receiving unit 4 is also different. Therefore, if there is unevenness in the film thickness distribution of the film 92, the two-dimensional image (original image and emphasized image) of the upper surface 91 of the substrate 9 generated by the image generation unit 71 of the inspection unit 7 is also a pixel. Unevenness occurs in the value of. In the unevenness inspection apparatus 1, the unevenness detection unit 72 of the inspection unit 7 inspects the degree of variation in the value of each pixel in the emphasized image on the upper surface 91, and an area in which the degree of variation is larger than a preset unevenness threshold value. If present, the corresponding region on the upper surface 91 is detected as a region where the film thickness unevenness exceeds the allowable range.

  FIG. 6 is a diagram showing the change in reflectance when the film thickness of the film 92 changes by 1 nm. Lines 201 to 203 in FIG. 6 correspond to the lines 101 to 103 in FIG. 5, and indicate fluctuations in reflectance with respect to S-polarized light, non-polarized light, and P-polarized light, respectively.

  As shown in FIG. 6, since the variation in reflectance with respect to S-polarized light is larger than the variation in reflectance with respect to non-polarized light or P-polarized light, the unevenness inspection apparatus 1 receives light at the light receiving unit 4 with the polarizer 6. By examining the film thickness unevenness based on the intensity distribution of the S-polarized light using the light to be S-polarized light, the film thickness variation can be acquired with high sensitivity as the pixel value variation in the enhanced image. As described above, the unevenness inspection apparatus 1 can detect the unevenness in film thickness with high accuracy by improving the sensitivity to the uneven film thickness.

  By the way, the reflectance of the film 92 varies with periodicity with respect to the variation of the film thickness as shown in FIG. 5, and in the vicinity of the maximum point and the minimum point of the reflectance as shown in FIGS. The variation of the reflectance with respect to the variation of the film thickness becomes very small. For this reason, in the case where the variation in the film thickness is slight, the pixel value hardly varies in the two-dimensional image (original image and enhanced image) generated by the image generation unit 71, and the unevenness ( That is, the accuracy of detection of film thickness fluctuations is reduced. Hereinafter, a region having a film thickness in which the ratio of the reflectance variation to the film thickness variation is extremely small is referred to as a “low sensitivity region”.

  If the film thickness of the film 92 on the substrate 9 fluctuates in the low sensitivity region of the line 101 in FIG. 5, such film thickness unevenness can be detected with high accuracy based only on the line 101. difficult. Therefore, in the unevenness inspection apparatus 1, as described above, one optical filter 51 is used as the selected optical filter 51 a to detect the first film thickness unevenness (step S <b> 23), and then the control unit 8 uses the wavelength band switching mechanism 5. The filter rotation motor 53 is driven to rotate the filter wheel 52, and the other optical filter 51 is arranged on the optical path from the substrate 9 to the light receiving unit 4 to change the selected wavelength band in the wavelength band switching mechanism 5 (step). S231). By changing the selected wavelength band, the low sensitivity region of the film thickness is also moved.

  Thereafter, the stage 2 is returned to the inspection start position by the moving mechanism 21, and the movement of the substrate 9 and the stage 2 is started again (step S11). In the unevenness inspection apparatus 1, S-polarized light having a selection wavelength band different from that at the time of the first unevenness detection is reflected among the reflected light on the substrate 9 of the light from the light emitting unit 3 until the stage 2 reaches the inspection end position. After the light receiving unit 4 receives the light and the intensity distribution of the reflected light from the linear irradiation region on the substrate 9 is repeatedly acquired and sent to the image generating unit 71 of the inspection unit 7, the movement of the substrate 9 and the stage 2 is performed. It stops and irradiation of illumination light is also stopped (steps S12 to S16).

  Then, an emphasized image of the upper surface 91 of the substrate 9 is generated by the image generation unit 71 of the inspection unit 7 (step S21), and the film thickness unevenness of the film 92 on the upper surface 91 is detected by the unevenness detection unit 72 (step S21). S22). When the second detection of film thickness unevenness is completed (step S23), the film thickness unevenness of the film 92 formed on the upper surface 91 of the substrate 9 is finally detected based on the first and second detection results. Detection of film thickness unevenness by the unevenness inspection apparatus 1 ends.

  In the unevenness inspection apparatus 1, the thickness of the first unevenness detection and the second unevenness detection is changed by switching the selected wavelength band between a plurality of different wavelength bands by the plurality of optical filters 51 of the wavelength band switching mechanism 5. The low sensitivity area is different. Thereby, even if a part (or all) of the fluctuation range of the film thickness of the film 92 is included in the low sensitivity region at the time of the first unevenness detection, for example, the low sensitivity is detected at the second unevenness detection. Since the regions are different, the portion included in the low sensitivity region at the time of the first unevenness detection can be detected with high sensitivity, and the film thickness unevenness can be detected with higher accuracy.

  In the unevenness inspection apparatus 1, by rotating the filter wheel 52 and switching the selected optical filter 51 a on the optical path from the substrate 9 to the light receiving unit 4 to another optical filter 51, the light receiving unit 4 receives light from the substrate 9. The wavelength band of reflected light (that is, the selected wavelength band) can be easily changed to an appropriate wavelength band. Further, by emitting linear light from the light emitting unit 3 and repeatedly receiving the reflected light from the substrate 9 moving in the direction perpendicular to the linear light while the substrate 9 is moving by the line sensor 41, The incident angle of light with respect to the substrate 9 can be made constant over the entire upper surface 91. Thereby, since it is not necessary to consider the influence of the incident angle on the reflectance in the detection of the film thickness unevenness, the process for detecting the film thickness unevenness by the unevenness detection unit 72 can be simplified.

  In the unevenness inspection apparatus 1, since the polarizer 6 is disposed between the substrate 9 and the line sensor 41 (that is, on the light path on the light receiving side), the influence of heat from the light emitting unit 3 on the polarizer 6 is prevented. be able to. Further, since the polarizer 6 is arranged between the substrate 9 and the wavelength band switching mechanism 5, the degree of freedom of arrangement of the polarizer 6 is increased, so that the configuration of the apparatus can be prevented from becoming complicated. .

  Next, the unevenness inspection apparatus 1a according to the second embodiment of the present invention will be described. FIG. 7 is a front view showing the configuration of the unevenness inspection apparatus 1a. In the unevenness inspection apparatus 1 a, the polarizer 6 is disposed on the optical path between the condenser lens 42 of the light receiving unit 4 and the line sensor 41. Other configurations are the same as those in FIG. 1, and the same reference numerals are given in the following description.

  The flow of film thickness unevenness inspection by the unevenness inspection apparatus 1a according to the second embodiment is substantially the same as that of the first embodiment, and will be described below with reference to FIGS. First, the movement of the substrate 9 and the stage 2 is started, and linear white light is emitted from the light emitting unit 3 and irradiated onto the linear irradiation region on the substrate 9 (steps S11 and S12).

  The light from the light emitting unit 3 is reflected by the upper surface 91 of the substrate 9 and passes through the selective optical filter 51a of the wavelength band switching mechanism 5 so that only light in the selected wavelength band is extracted and guided to the light receiving unit 4. It is burned. In the light receiving unit 4, the light in the selected wavelength band from the wavelength band switching mechanism 5 is collected by the condenser lens 42 and guided to the polarizer 6, and only the S-polarized light is extracted by passing through the polarizer 6. The light is received while being imaged on the line sensor 41 (step S13). The intensity distribution in the selected wavelength band of the S-polarized light out of the reflected light from the linear irradiation region on the substrate 9 is acquired and sent to the image generation unit 71 of the inspection unit 7 (step S14).

  In the unevenness inspection apparatus 1a, the reflected light from the upper surface 91 is obtained by repeatedly acquiring the intensity distribution of the reflected light from the linear irradiation region on the substrate 9 until the stage 2 reaches the inspection end position (step S15). Among these, the intensity distribution in the selected wavelength band of the S-polarized light is acquired (steps S13 to S16). Thereafter, the movement of the substrate 9 and the stage 2 and the irradiation of illumination light are stopped (step S17), and an enhanced image is generated by the image generation unit 71 and the film thickness unevenness of the film 92 formed on the upper surface 91 is uneven. It is detected (steps S21 and S22).

  When the first detection of film thickness unevenness is completed, the wavelength band switching mechanism 5 changes the selected wavelength band (steps S23 and S231), and the process returns to step S11 to detect the second film thickness unevenness (step S11). To S17, S21 to S23). Based on the first and second detection results, the film thickness unevenness of the film 92 formed on the upper surface 91 of the substrate 9 is finally detected, and the film thickness unevenness detection by the unevenness inspection apparatus 1a ends.

  As described above, in the unevenness inspection apparatus 1a, the light received by the light receiving unit 4 by the polarizer 6 is S-polarized light, so that the film of the line sensor 41 is the same as in the first embodiment. It is possible to improve the sensitivity to thickness unevenness and detect film thickness unevenness with high accuracy. Moreover, since the polarizer 6 is disposed between the substrate 9 and the line sensor 41 (that is, on the light path on the light receiving side), the influence of heat from the light emitting unit 3 on the polarizer 6 can be prevented. In the unevenness inspection apparatus 1a, in particular, since the polarizer 6 is disposed between the condenser lens 42 and the line sensor 41, the polarizer 6 has a size corresponding to the linear light collected by the condenser lens 42. can do. Therefore, compared with the case where the polarizer 6 is disposed in front of the condenser lens 42 (for example, on the optical path from the light emitting unit 3 to the condenser lens 42), the polarizer 6 can be reduced in size.

  In the unevenness inspection apparatus 1a, similarly to the first embodiment, the low sensitivity region of the film thickness at the time of unevenness detection is appropriately changed by detecting the film thickness unevenness twice by changing the selected wavelength band. In addition, film thickness unevenness can be detected with higher accuracy. Further, by rotating the filter wheel 52 and switching the selected optical filter 51a to another optical filter 51, the wavelength band of reflected light from the substrate 9 that is received by the light receiving unit 4 (that is, the selected wavelength band) can be easily obtained. Can be changed. Furthermore, since the linear light from the light emitting portion 3 is repeatedly received by the line sensor 41 during the movement of the substrate 9, the incident angle of the light with respect to the substrate 9 can be made constant over the entire upper surface 91. It is possible to simplify the detection processing of the film thickness unevenness by the detection unit 72.

  Next, an unevenness inspection apparatus 1b according to the third embodiment of the present invention will be described. FIG. 8 is a front view showing the configuration of the unevenness inspection apparatus 1b. In the unevenness inspection apparatus 1 b, the polarizer 6 is disposed on the optical path between the cylindrical lens 33 of the light emitting unit 3 and the substrate 9. Other configurations are the same as those in FIG. 1, and the same reference numerals are given in the following description.

  The flow of film thickness unevenness inspection by the unevenness inspection apparatus 1b according to the third embodiment is substantially the same as that of the first embodiment, and will be described below with reference to FIGS. First, the movement of the substrate 9 and the stage 2 is started, and linear white light is emitted from the light emitting unit 3, and only the S-polarized light is extracted by passing through the polarizer 6. The irradiation area is irradiated (steps S11 and S12).

  Subsequently, the S-polarized light reflected by the upper surface 91 of the substrate 9 is transmitted through the selection optical filter 51 a of the wavelength band switching mechanism 5, whereby only the light in the selected wavelength band is extracted, and the condensing lens 42 of the light receiving unit 4. And is received while being focused on the line sensor 41 (step S13). Then, the intensity distribution of the S-polarized light in the selected wavelength band is acquired and sent to the image generation unit 71 of the inspection unit 7 (step S14).

  Hereinafter, similarly to the first embodiment, after the intensity distribution of the reflected light from the linear irradiation region on the substrate 9 is repeatedly acquired until the stage 2 reaches the inspection end position, the film is detected by the unevenness detection unit 72. The film thickness unevenness 92 is detected (steps S15 to S22). Next, the selected wavelength band is changed in the wavelength band switching mechanism 5 (steps S23 and S231), and the process returns to step S11 to detect the second film thickness unevenness (steps S11 to S17 and S21 to S23). Based on the first and second detection results, the film thickness unevenness of the film 92 formed on the upper surface 91 of the substrate 9 is finally detected, and the film thickness unevenness detection by the unevenness inspection apparatus 1b ends.

  As described above, in the unevenness inspection apparatus 1b, the light received by the light receiving unit 4 by the polarizer 6 is changed to S-polarized light, so that the film of the line sensor 41 is the same as in the first embodiment. It is possible to improve the sensitivity to thickness unevenness and detect film thickness unevenness with high accuracy. In particular, the film thickness unevenness of the substrate 9 on which the film 92 having a relatively rough surface (for example, the film 92 in which the ratio of scattered light contained in the light reflected by the substrate 9 to the regular reflection light is 1% or more) is formed. When the inspection is performed, the polarizer 6 is disposed between the substrate 9 and the line sensor 41 by arranging the polarizer 6 between the light emitting unit 3 and the substrate 9 (that is, on the light path on the emission side). The film thickness unevenness can be detected with higher accuracy than in the case of being arranged on the light path on the light receiving side.

  In the unevenness inspection apparatus 1b, as in the first embodiment, it is possible to detect film thickness unevenness more accurately by changing the selected wavelength band and detecting the film thickness unevenness twice. Further, by switching the selected optical filter 51a to another optical filter 51, the wavelength band of reflected light from the substrate 9 that is received by the light receiving unit 4 (that is, the selected wavelength band) can be easily changed. Furthermore, by detecting the linear light from the light emitting unit 3 repeatedly while the substrate 9 is moved by the line sensor 41, it is possible to simplify the process of detecting the film thickness unevenness by the unevenness detecting unit 72.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to the said embodiment, A various change is possible.

  For example, the stage 2 may be moved relative to the light emitting unit 3, the light receiving unit 4, the wavelength band switching mechanism 5, and the polarizer 6, and the stage 2 is fixed, and the light emitting unit 3, the light receiving unit 4, The wavelength band switching mechanism 5 and the polarizer 6 may be moved while being fixed to each other.

  In the unevenness inspection apparatus according to the above embodiment, when the light emitted from the halogen lamp 31 includes light in a wavelength band that adversely affects the film 92 formed on the substrate 9, A filter or the like that does not transmit light is provided on the optical path from the halogen lamp 31 to the substrate 9. In addition, when the film 92 on the upper surface 91 of the substrate 9 is transparent to infrared light, a light source that emits infrared light may be provided in the light emitting unit 3 instead of the halogen lamp 31 that emits white light.

  In the light emitting unit 3, a fiber array in which a plurality of optical fibers are linearly arranged is provided in place of the quartz rod 32, and light from the halogen lamp 31 is converted into linear light by passing through the fiber array. Also good. Further, instead of the halogen lamp 31 and the quartz rod 32, a plurality of light source elements arranged in a straight line may be provided as a light source that emits linear light.

  From the viewpoint of simplifying the detection process of the film thickness unevenness by making the incident angle of light with respect to the substrate 9 constant over the entire upper surface 91, the light emitting portion 3 is detected by the line sensor 41 that moves relative to the substrate 9. However, when it is necessary to shorten the imaging time of the substrate 9, a two-dimensional CCD sensor is provided in the light receiving unit 4 instead of the line sensor 41. Also good.

  From the standpoint of receiving S-polarized light by the line sensor 41, the polarizer 6 may be disposed anywhere on the optical path from the light emitting unit 3 to the line sensor 41. For example, the polarizer 6 may be combined with the selective optical filter 51a. You may arrange | position between the optical lenses 42.

  The wavelength band switching mechanism 5 is not necessarily disposed on the optical path from the substrate 9 to the light receiving unit 4, and may be disposed on the optical path from the light emitting unit 3 to the substrate 9, for example. The switching of the selected wavelength band by the wavelength band switching mechanism 5 is not limited to the switching of the plurality of optical filters 51, and a plurality of light sources that emit light of a plurality of different wavelength bands are provided in the light emitting unit 3. The wavelength band of light emitted from the light emitting unit 3 may be switched by controlling a plurality of light sources by the wavelength band switching mechanism 5.

  In the unevenness inspection apparatus according to the above-described embodiment, the film thickness unevenness of the film 92 is detected by inspecting the degree of variation in the value of each pixel in the emphasized image on the upper surface 91 by the unevenness detection unit 72. The detection of the thickness unevenness may be performed by the operator visually comparing the emphasized image of the upper surface 91 displayed on the display or the like and comparing it with the reference image.

  The unevenness inspection apparatus according to the above embodiment may be used for detection of film thickness unevenness of other films other than the resist film, for example, an insulating film or a conductive film formed on the substrate 9. It may be formed by a method other than coating of the coating solution, for example, vapor deposition, chemical vapor deposition (CVD), sputtering, or the like. In addition, the unevenness inspection apparatus may be used for inspection of film thickness unevenness of a film formed on another substrate such as a semiconductor substrate.

It is a figure which shows the structure of the nonuniformity inspection apparatus which concerns on 1st Embodiment. It is a figure which shows a wavelength band switching mechanism. It is a figure which shows the flow of a test | inspection of film thickness nonuniformity. It is a figure which shows the flow of a test | inspection of film thickness nonuniformity. It is a figure which shows the relationship between a film thickness and a reflectance. It is a figure which shows the relationship between a film thickness and the fluctuation | variation of a reflectance. It is a figure which shows the structure of the nonuniformity inspection apparatus which concerns on 2nd Embodiment. It is a figure which shows the structure of the nonuniformity inspection apparatus which concerns on 3rd Embodiment.

Explanation of symbols

1, 1a, 1b Unevenness inspection apparatus 2 Stage 3 Light emitting part 5 Wavelength band switching mechanism 6 Polarizer 9 Substrate 21 Moving mechanism 31 Halogen lamp 32 Quartz rod 33 Cylindrical lens 41 Line sensor 42 Condensing lens 51 Optical filter 51a Selective optical filter 52 Filter wheel 53 Filter rotation motor 91 Upper surface 92 Film S11-S17, S21-S23, S231 Step

Claims (9)

An unevenness inspection apparatus for inspecting film thickness unevenness of a film formed on a substrate,
A holding unit for holding a substrate on which a light-transmitting film is formed on the main surface;
A light emitting portion for emitting light incident on the film at an angle;
A sensor that receives light in a specific wavelength band after being reflected by the film and acquires an intensity distribution of the light in the specific wavelength band from the film;
A polarizer that is disposed on an optical path from the light emitting section to the sensor and selectively transmits S-polarized light to the film;
A nonuniformity inspection apparatus comprising: The unevenness inspection apparatus according to claim 1,
The unevenness inspection apparatus further comprising wavelength band switching means for switching the specific wavelength band between a plurality of different wavelength bands. The unevenness inspection apparatus according to claim 2,
The light emitting part emits light including light of a plurality of wavelength bands;
The wavelength band switching means,
A plurality of optical filters that selectively transmit light of the plurality of wavelength bands, respectively;
An optical filter switching mechanism that changes the specific wavelength band by switching one optical filter arranged on the optical path among the plurality of optical filters to another optical filter;
A nonuniformity inspection apparatus comprising: The unevenness inspection apparatus according to any one of claims 1 to 3,
The unevenness inspection apparatus, wherein the polarizer is disposed between the substrate and the sensor. The unevenness inspection apparatus according to claim 4,
A condenser lens that is disposed on an optical path from the substrate to the sensor and collects the light of the specific wavelength band toward the sensor;
The unevenness inspection apparatus, wherein the polarizer is disposed between the condenser lens and the sensor. The unevenness inspection apparatus according to any one of claims 1 to 3,
The unevenness inspection apparatus, wherein the polarizer is disposed between the light emitting portion and the substrate. The unevenness inspection apparatus according to claim 6,
An unevenness inspection apparatus, further comprising a condensing lens that is disposed on an optical path from the substrate to the sensor and collects light of the specific wavelength band toward the sensor. The unevenness inspection apparatus according to any one of claims 1 to 7,
A moving mechanism for moving the holding unit relative to the light emitting unit and the sensor in a predetermined moving direction along the main surface of the substrate;
The light emitting part is
A light source;
An illumination optical system that converts the light from the light source into linear light that extends along the main surface and extends in a direction perpendicular to the moving direction, and guides the light to the film;
With
The unevenness inspection apparatus, wherein the sensor is a line sensor that repeatedly acquires an intensity distribution of light of the specific wavelength band from an irradiation region on the substrate of the linear light during movement of the holding unit. . An unevenness inspection method for inspecting film thickness unevenness of a film formed on a substrate,
Emitting light incident on the main surface of the substrate on which the light-transmitting film is formed at an angle with respect to the film;
Light having a specific wavelength band after being reflected by the film and transmitted through a polarizer that selectively transmits S-polarized light to the film before or after being reflected by the film. Receiving light to obtain an intensity distribution of light of the specific wavelength band from the film;
An unevenness inspection method comprising:

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