JP2012080001A - Inspection method and inspection device of polycrystalline silicon thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection method and an inspection device of a polycrystalline silicon thin film capable of detecting an image on the surface of the polycrystalline silicon thin film, observing the surface state of the polycrystalline silicon thin film, and inspecting the crystal state of the polycrystalline silicon thin film.SOLUTION: An inspection device of a polycrystalline silicon thin film comprises: light irradiation means 800 which irradiates a substrate 100 on which the polycrystalline silicon thin film is formed on its surface with light; imaging means 820 which takes an image of a scattered light from the polycrystalline silicon thin film in the vicinity of the light which transmitted the polycrystalline silicon thin film among the lights with which the light irradiation means 800 irradiated the substrate 100 or of the light specularly reflected on the polycrystalline silicon thin film; and image processing means 740 which processes the image of the scattered light taken by the imaging means 820 and inspects the crystal state of the polycrystalline silicon thin film.

Description

  The present invention relates to a method and apparatus for inspecting a crystal state of a polycrystalline silicon thin film obtained by polycrystallizing amorphous silicon formed on a substrate by laser annealing.

  Thin film transistors (TFTs) used in liquid crystal display elements and organic EL (Electro Luminescence) elements are annealed at low temperatures using excimer lasers on a portion of amorphous silicon formed on the substrate to ensure high-speed operation. By doing so, it is formed in a polycrystallized region.

  As described above, when a part of amorphous silicon is annealed at a low temperature with an excimer laser to be polycrystallized, it is required to uniformly polycrystallize, but in reality, the crystallinity varies due to the influence of fluctuations in the laser light source. May occur.

  Therefore, as a method of monitoring the occurrence state of the variation of the silicon crystal, Patent Document 1 discloses that the semiconductor film is irradiated with a pulse laser to perform laser annealing and the laser irradiation region is irradiated with inspection light, and the irradiated inspection light is irradiated. It is described that the reflected light from the substrate is detected and the state of crystallization of the semiconductor film is confirmed from the intensity change of the reflected light.

  In Patent Document 2, the amorphous silicon before the laser irradiation is irradiated with the inspection light and the reflected light or the transmitted light is detected, and the inspection light is emitted even during the irradiation of the laser to the amorphous silicon. Irradiate and detect the reflected or transmitted light, and return to the intensity of the reflected or transmitted light before the laser irradiation from the time when the difference in intensity between the reflected light or transmitted light before the laser irradiation and during the laser irradiation becomes maximum It is described that the time of the laser annealing is detected to monitor the state of laser annealing.

  Further, Patent Document 3 irradiates a region where amorphous silicon formed on a substrate is changed into polycrystalline silicon by excimer laser annealing with visible light from a direction of 10 to 85 degrees with respect to the substrate surface. It is described that reflected light is detected by a camera grounded in the same angle range as that of irradiation, and the arrangement state of protrusions on the crystal surface is inspected from the change of the reflected light.

  Further, in Patent Document 4, a polycrystalline silicon thin film formed by irradiating an excimer laser on an amorphous silicon film is irradiated with inspection light, and diffracted light from the polycrystalline silicon thin film is monitored by a diffracted light detector. By utilizing the fact that the intensity of diffracted light generated from a region with a regular fine concavo-convex structure with high crystallinity of a silicon thin film is higher than the intensity of diffracted / scattered light from a region with low crystallinity, a polycrystalline silicon thin film It is described that the state of the test is inspected.

JP 2002-305146 A Japanese Patent Laid-Open No. 10-144621 JP 2006-19408 A JP 2001-308209 A

  It is known that the surface of a polycrystalline silicon thin film (polysilicon film) formed by annealing an amorphous silicon thin film by irradiating it with an excimer laser is generated with a period having fine irregularities. These fine protrusions reflect the degree of crystallinity of the polycrystalline silicon thin film, and there are fine irregularities on the surface of the polycrystalline silicon thin film having a uniform crystalline state (with a uniform polycrystalline grain size). It is known that fine irregularities are irregularly formed on the surface of a polycrystalline silicon thin film that is periodically formed with a certain regularity and has low uniformity of crystal state (polycrystalline grain size is not uniform). .

  As described above, as a method for inspecting the surface state of the polycrystalline silicon thin film in which the crystal state is reflected in the reflected light, Patent Document 1 discloses that the intensity of the reflected light of the light irradiated to the laser annealed region is changed from that of the semiconductor film. Although it is described that the state of crystallization is confirmed, the crystallization state is monitored in-process, and since the detection light is a laser for annealing, scattering that always reflects the state of the crystal There is no description of detecting scattered light that is not detectable by light and reflects the state of the crystal.

  Patent Document 2 monitors the progress of annealing by comparing the reflected light from the laser irradiation area during laser annealing with the reflected light before annealing. It is for monitoring the crystallization state, and the detection light is an annealing laser, and there is no description about detecting scattered light reflecting the crystal state.

  On the other hand, Patent Document 3 describes that the quality of polycrystalline silicon crystal is inspected by the change of light reflected by the arrangement of protrusions on the surface of the polycrystalline silicon thin film formed by laser annealing. No consideration is given to changes in the amount of reflected light (diffracted light) and its distribution according to the growth of the crystal grain size of the silicon thin film.

  Further, Patent Document 4 describes the detection of diffracted light generated by protrusions on the surface of a polycrystalline silicon thin film formed by laser annealing, but the intensity level of diffracted light detected by a diffracted light detector. Is used to inspect the state of the polycrystalline silicon film, and to detect the image of the surface of the polycrystalline silicon thin film and observe the state of the protrusion on the surface of the polycrystalline silicon thin film. It has not been.

  The object of the present invention is to solve the above-mentioned problems of the prior art, observe the surface state of the polycrystalline silicon thin film from an image obtained by taking an optical image of the surface of the polycrystalline silicon thin film, It is an object of the present invention to provide a method and an apparatus for inspecting a polycrystalline silicon thin film that makes it possible to inspect the state of the crystal.

  In order to solve the above-described problems of the prior art, in the present invention, a polycrystalline silicon thin film inspection apparatus includes a light irradiation means for irradiating light onto a substrate having a polycrystalline silicon thin film formed thereon, and the light irradiation means. A first imaging means for capturing an image of scattered light from the polycrystalline silicon thin film in the vicinity of light transmitted through the polycrystalline silicon thin film or reflected by the polycrystalline silicon thin film among the light irradiated to the substrate by A second imaging unit that captures an image of the first-order diffracted light generated from the polycrystalline silicon thin film irradiated with light by the irradiating unit, an image of the scattered light obtained by imaging with the first imaging unit, and a second imaging Image processing means for inspecting the crystal state of the polycrystalline silicon thin film by processing an image of the first-order diffracted light obtained by imaging with the means.

  In order to solve the above-described problems of the prior art, in the present invention, as a method for inspecting a polycrystalline silicon thin film, a substrate having a polycrystalline silicon thin film formed on the surface is irradiated with light, and the substrate is irradiated with light. Takes an image of scattered light from the polycrystalline silicon thin film in the vicinity of the light transmitted through the polycrystalline silicon thin film or the light regularly reflected by the polycrystalline silicon thin film, and the light irradiated on the substrate from the polycrystalline silicon thin film. The image of the generated first-order diffracted light is picked up, and the image obtained by picking up the image of scattered light and the image obtained by picking up the image of the first-order diffracted light are processed to inspect the crystal state of the polycrystalline silicon thin film. It was made to do.

  According to the present invention, the crystal state of a polycrystalline silicon thin film formed by annealing with an excimer laser can be inspected with relatively high accuracy, and the quality of an organic EL glass substrate or a liquid crystal display glass substrate is improved. It becomes possible to maintain.

It is a figure for demonstrating the principle of this invention, Comprising: It is sectional drawing of a board | substrate which shows the relationship between the 1st-order diffracted light and substrate transmission light which generate | occur | produce when light is irradiated from the back surface to the board | substrate with which the polycrystalline silicon film was formed. is there. It is a graph which shows the qualitative relationship between the laser power at the time of annealing an amorphous silicon film with a laser, and the crystal grain diameter of a polycrystalline silicon. It is a graph which shows the relationship between the diffraction angle of the 1st-order diffracted light which generate | occur | produces from a board | substrate when the light with a wavelength of 0.4 micrometer is irradiated to the board | substrate with which the polycrystalline silicon film was formed, and the crystal grain diameter of a polycrystalline silicon film. For each of the substrates (1) to (5), 1st order diffracted light from the substrate when the laser power is changed and annealed is detected at an angle θ2 with respect to the substrate using a one-dimensional sensor array. It is the graph which plotted the output of each pixel of a two-dimensional sensor array. It is the graph which plotted the average value of the output value of the 1-dimensional sensor array of the P point of the graph of (1) to (5) of FIG. 3, and its vicinity, and the laser power at the time of annealing. Each of the substrates (1) to (5) of FIG. 3 annealed by changing the laser power is irradiated with light from the back surface of the substrate, and an image of scattered light near the light transmitted through the substrate is a one-dimensional sensor array. Is a graph plotting output values of each pixel of a one-dimensional sensor array when detected using. In the graph of FIG. 4, the average value of the outputs of the P point and the neighboring pixels and the output of each pixel in which the scattered light image of FIG. 5 is added are plotted, and the laser power during annealing is plotted on the horizontal axis. It is. It is a block diagram which shows the structure of the whole inspection apparatus of the polycrystalline silicon thin film in the Example of this invention. It is a block diagram which shows the schematic structure of the test | inspection unit and test | inspection data processing and control part in 1st Example of this invention. It is a block diagram which shows the structure of the outline of the modification of the test | inspection unit and test | inspection data processing and control part in 1st Example of this invention. It is a flowchart which shows the sequence of the imaging in 1st Example of this invention. It is a flowchart which shows the sequence of the image processing in 1st Example of this invention. It is a block diagram which shows the schematic structure of the test | inspection unit and test | inspection data process and control part in 2nd Example of this invention. It is a block diagram which shows the structure of the outline of the modification of the test | inspection unit and test | inspection data processing / control part in 2nd Example of this invention.

  As an embodiment of the present invention, an example applied to an apparatus for inspecting a polycrystalline silicon thin film formed on a glass substrate for organic EL or a glass substrate for liquid crystal display will be described.

  First, the principle of the present invention will be described with reference to FIGS.

  In an organic EL or liquid crystal display glass substrate 100 (hereinafter referred to as a substrate) shown in FIG. 1, an amorphous silicon thin film 110 is formed on the substrate. By irradiating a part of the amorphous silicon thin film 110 with an excimer laser (not shown) and scanning, the part of the amorphous silicon thin film 110 irradiated with the excimer laser is sequentially heated and melted. After the excimer laser is scanned, the melted amorphous silicon thin film 110 is gradually cooled, so that the silicon is polycrystallized, and a crystal grows in the state of polycrystal silicon. In the present invention, it is inspected whether or not the polycrystalline silicon is formed as a normal film in a state where the crystal grains are aligned in a desired size.

  In FIG. 1, a part of an amorphous silicon thin film 110 formed on a glass substrate 100 is subjected to excimer laser annealing to form a polycrystalline silicon thin film 120 with a uniform crystal grain size. Illuminating light 151 is irradiated from the back surface side of the substrate 100 at an incident angle θ1, and the first-order diffracted light 152 is generated in the θ2 direction on the front surface side of the substrate 100.

  The grain size of the polycrystalline silicon thin film 120 formed by this excimer laser annealing depends on the irradiation energy of the excimer laser (the product of the laser power density and the irradiation time). This relationship is qualitatively expressed as shown in FIG. 2A. That is, as the power of the laser irradiating the amorphous silicon thin film 110 is increased, the crystallization of the amorphous silicon thin film 110 starts to progress from a certain energy level, and the polycrystalline silicon thin film 120 grows. As the power of the laser to be irradiated is further increased, the grain size of the polycrystalline silicon thin film 120 grows larger.

  Here, when the polycrystalline silicon thin film 120 has a uniform grain size, protrusions are formed on the surface of the polycrystalline silicon thin film 120 at a substantially constant pitch P according to the grain size of the crystal (FIG. 1 drawing). Projections are formed at a constant pitch in a direction perpendicular to the surface). The pitch P of the protrusions on the film surface varies depending on the crystal grain size of the polycrystalline silicon thin film 120.

On the other hand, in the configuration shown in FIG. 1, the incident angle θ1 of the illumination light emitted from the light source 150 with the wavelength λ to the substrate 100 and the first-order diffracted light generated from the substrate 100 on which the polycrystalline silicon thin film 120 is formed. Between the emission angle θ2 and the pitch P of the protrusions on the surface of the polycrystalline silicon thin film 120,
sin θ1 + sin θ2 = λ / P (Equation 1)
The relationship expressed by

  Now, assuming that the incident angle θ1 of the illumination light to the substrate 100 is 75 degrees and the wavelength λ of the illumination light is 400 nm, the emission angle θ2 of the first-order diffracted light and the pitch P of the protrusions on the surface of the polycrystalline silicon thin film 120 are The relationship is as shown in 2B.

  That is, if there is variation (distribution) or variation (time-dependent change) in the power of the excimer laser when annealing the amorphous silicon thin film 110, the grain size of the polycrystalline silicon thin film 120 changes from the relationship shown in FIG. 2A. . As a result, from the relationship shown in FIG. 2B, the emission angle θ2 of the first-order diffracted light generated from the substrate 100 irradiated from the direction of θ1 changes. Therefore, when the angle for detecting the first-order diffracted light of the optical system (not shown in FIG. 1) for detecting the first-order diffracted light 152 is fixed, the first-order diffracted light is detected when the grain size of the polycrystalline silicon thin film 120 changes. And the reliability of the inspection of the polycrystalline silicon thin film 120 may be impaired.

  3 shows that the substrate 100 annealed by changing the power of the excimer laser is irradiated with a long illumination light 151 in a direction perpendicular to the paper surface emitted from the light source 150 as shown in FIG. 1, and fixed in the direction of θ2. The example which plotted the output from each element of a one-dimensional sensor array when it detects with the one-dimensional sensor array long in the direction perpendicular | vertical with respect to the paper surface which is not shown in figure is shown.

  (1) in FIG. 3 shows a case where the substrate 100 annealed with the lowest excimer laser power is irradiated with a long illumination light 151 in a direction perpendicular to the paper surface and detected by a one-dimensional sensor array. The example which plotted the output from each element of a one-dimensional sensor array is shown. An output from the one-dimensional sensor array reflecting the annealing state according to the intensity distribution of the excimer laser is obtained. In the example of (1) in FIG. 3, since the power of the excimer laser at the time of annealing is insufficient, the luminance exceeding the level of the threshold value 301 cannot be detected by the output from the one-dimensional sensor array.

  (2) to (5) in FIG. 3 are obtained from each element of the one-dimensional sensor array when the illumination light 151 is irradiated onto the annealed substrate 100 by sequentially increasing the power of the excimer laser with respect to the case of (1). Is a plot of the output of. (5) shows a case where annealing is performed with a laser power that does not damage the substrate 100. The distribution pattern of the light emitted in the direction of θ2 from the substrate 100 irradiated with the illumination light 151 changes according to the change in the excimer laser power during annealing.

  4 shows a one-dimensional sensor array corresponding to point P in FIG. 3 (1) to (5) and its vicinity (region sandwiched by solid lines on both sides of point P in FIG. 3 (1) to (5)). It shows the relationship between the average value of the output from the element and the excimer laser power during annealing.

  The hatched portion in FIG. 4 falls below the threshold value set at the level of the luminance value even when the laser power during annealing is below the limit value that damages the substrate 100, and laser annealing is performed. Is determined to be defective. This is a false detection.

  On the other hand, in the configuration of FIG. 1, transmitted light (direct light from the light source 150) that travels straight in the direction of 152 indicated by the dotted line through the substrate 100 among the illumination light 151 irradiated to the substrate 100. When the scattered light around the transmitted light is detected with the light shielded, the scattered light around the transmitted light is less affected by the size of the polycrystalline silicon thin film 120 when the grain size of the polycrystalline silicon thin film 120 becomes larger than a certain level.

  5 corresponds to the vicinity of the pixel P described in FIG. 3 among the outputs of the one-dimensional sensor array element that detects the scattered light in the vicinity of the transmitted light transmitted through the substrate 100 when the substrate 100 is irradiated with the illumination light 151. 3 shows the relationship between the average value of the output values from the element that detects the scattered light from the region to be irradiated and the excimer laser power during annealing.

  From this figure, it can be seen that the scattered light in the vicinity of the transmitted light transmitted through the substrate 100 becomes larger as the annealing power is lower and becomes smaller as the annealing power is increased.

  FIG. 6 shows the result of adding the result of detecting the first-order diffracted light shown in FIG. 4 and the result of detecting the scattered light in the vicinity of the transmitted light shown in FIG.

  In the case of FIG. 4, even if the hatched portion is in a state where the laser power during annealing is not more than a limit value that does not damage the substrate 100, the laser becomes below the threshold value set at the level of the luminance value. Although it was erroneously determined that the annealing was defective, it can be seen in FIG. 6 that the OK range on the side where the laser power during annealing is high can be expanded. That is, the lower limit value of the laser power during annealing is determined from the detection data of the first-order diffracted light shown in FIG. 4, and the detection data of the first-order diffracted light and the detection data of scattered light in the vicinity of the transmitted light shown in FIG. By determining the upper limit value of the laser power during annealing from the combined result, the setting range of the laser power during annealing can be further expanded.

  The example shown in FIG. 6 shows an example in which data obtained by detecting the first-order diffracted light shown in FIG. 4 and data obtained by detecting scattered light near the transmitted light shown in FIG. 5 are simply added. A weight may be added to the data in which the scattered light near the transmitted light shown in FIG. 5 is detected, and the data may be added to the data in which the first-order diffracted light shown in FIG. 4 is detected. In this case, from the result of adding both pieces of detection data corresponding to FIG. 6, the OK range on the side where the laser power during annealing is higher can be expanded and detected.

  The present invention has been made based on the above-described principle, and a specific configuration of an inspection apparatus for implementing the principle of the present invention will be described below.

  The entire configuration of an inspection apparatus 700 for inspecting the crystal state of a polycrystalline silicon thin film formed by laser annealing on a part of an amorphous silicon film on an organic EL glass substrate or a liquid crystal display glass substrate according to the present invention. As shown in FIG.

  The inspection apparatus 700 includes a substrate loading unit 710, an inspection unit 720, a substrate unloading unit 730, an inspection unit data processing / control unit 740, and an overall control unit 750.

  A glass substrate for organic EL or a glass substrate for liquid crystal display (hereinafter referred to as a substrate) 100 to be inspected has an amorphous silicon thin film formed on the glass substrate, and a partial area in the process immediately before this inspection process. When the region heated by the excimer laser is scanned and heated, the overheated region is annealed and the silicon is polycrystallized into a polycrystalline silicon thin film state. The inspection apparatus 100 images the surface of the substrate 100 and examines whether this polycrystalline silicon thin film is normally formed.

  The substrate 100 to be inspected is set on the load unit 710 by a transfer means (not shown). The substrate 100 set on the load unit 710 is transported to the inspection unit 720 by a transport unit (not shown) controlled by the overall control unit 750. The inspection unit is provided with an inspection unit 721 and inspects the state of the polycrystalline silicon thin film formed on the surface of the substrate 100 under the control of the inspection data processing / control unit 740. The data detected by the inspection unit 721 is processed by the inspection data processing / control unit 740 to evaluate the state of the polycrystalline silicon thin film formed on the surface of the substrate 100.

  The substrate 100 that has been inspected is transferred from the inspection unit 720 to the unload unit 730 by a transfer unit (not shown) controlled by the overall control unit 750, and is taken out from the inspection apparatus 700 by a handling unit (not shown). FIG. 7 shows a configuration in which one inspection unit 721 is provided in the inspection unit 720. However, depending on the size of the substrate 100 to be inspected and the area and arrangement of the formed polycrystalline silicon thin film. There may be two or three or more.

  The configuration of the inspection unit 721 and the inspection unit data processing / control unit 740 in the inspection unit 720 is shown in FIG. 8A.

  The inspection unit 721 includes an illumination optical system 800, a scattered light image capturing optical system 820, a first-order diffracted light image capturing optical system 830, and a substrate stage 850, and is connected to the inspection unit data processing / control unit 740. The inspection unit data processing / control unit 740 is connected to the overall control unit 750 shown in FIG.

  The illumination optical system 800 includes a light source 801 that emits light of multiple wavelengths, a magnifying lens 802, a collimating lens 803, a wavelength filter 804, a polarizing filter 805, and a cylindrical lens 806, which are housed in a lens barrel 810.

  The light source 801 emits light having a wide frequency (for example, 300 nm to 700 nm) from the ultraviolet region to the visible region. For example, a halogen lamp, a xenon lamp, or the like is used.

  The magnifying lens 802 expands the beam diameter of the light emitted from the light source 801. The collimating lens 803 emits the light whose beam diameter is enlarged by the magnifying lens 802 as parallel light.

  The wavelength filter 804 is for selecting a wavelength to be illuminated according to the state of the polycrystalline silicon 120 formed on the substrate 100 to be inspected, and from among the multi-wavelength light emitted from the light source 801, A wavelength suitable for inspection can be selected.

  The polarizing filter 805 is for controlling the polarization state of light that illuminates the substrate 100, and can detect an image with high contrast according to the state of the polycrystalline silicon 120 formed on the substrate 100 to be inspected. Thus, the polarization state of the illumination light can be changed.

  The cylindrical lens 806 is illuminated so that the light emitted from the light source 801, condensed by the magnifying lens 802, and collimated by the collimating lens 803 can be efficiently illuminated according to the size of the inspection region on the substrate 100. The light beam is condensed in one direction, and in a direction perpendicular to the light beam, a cross-sectional shape is formed in one direction (perpendicular to the drawing) in a parallel light state. By irradiating the substrate 100 with light condensed in one direction by the cylindrical lens 806, the amount of illumination light in the inspection region on the substrate 100 is increased, and the scattered light image capturing optical system 820 and the first order diffracted light image capturing optical system 830 are used. Therefore, it is possible to detect an image with higher contrast.

  The scattered light imaging optical system 820 includes a light shielding plate 821 that shields transmitted light (direct light from the light source 801) emitted from the light source 801 and transmitted through the substrate 100, an objective lens 822, a wavelength filter 823, a polarizing filter 824, An imaging lens 825 and an image sensor 826 are provided, and these are housed in the lens barrel portion 827.

  The objective lens 822 is for condensing diffracted light (first-order diffracted light) generated from the substrate 100 illuminated by the illumination optical system 800, and has a relatively large NA (lens) for condensing the diffracted light efficiently. Have a numerical aperture of :).

  The wavelength filter 823 selectively transmits light having a specific wavelength among the light from the substrate 100 collected by the objective lens 822, and the optical characteristics of the polycrystalline silicon thin film formed on the surface of the substrate 100. The wavelength to be selected can be set in accordance with. The wavelength filter 823 can cut light having a wavelength other than the illumination wavelength from the substrate 100 and the periphery.

  The polarization filter 824 adjusts the polarization state of light having a specific wavelength that has passed through the wavelength selection filter 823.

  The imaging lens 825 is for forming an optical image by the first-order diffracted light from the surface of the substrate 100, and the polarization state is adjusted by the polarization filter 824 with light having a specific wavelength that has passed through the wavelength selection filter 823. An image of the emitted light is formed.

  The image sensor 826 captures an optical image by first-order diffracted light from a pattern formed in a long region in one direction of the surface of the substrate 100 illuminated by the cylindrical lens 805 imaged by the imaging lens 825. It is composed of a one-dimensional CCD (electrically coupled device) image sensor or a two-dimensional CCD image sensor arranged in accordance with a long illuminated area of the substrate 100.

  The first-order diffracted light image pickup optical system 830 includes an objective lens 831, a wavelength filter 832, a polarization filter 833, an imaging lens 834, and an image sensor 835, and these are housed in a lens barrel portion 836.

  The objective lens 831 is for converging the diffracted light (first-order diffracted light) generated from the substrate 100 illuminated by the illumination optical system 800, and has a relatively large NA (lens) for condensing the diffracted light efficiently. Have a numerical aperture of :).

  The wavelength filter 832 selectively transmits light having a specific wavelength among the light from the substrate 100 collected by the objective lens 831, and the optical characteristics of the polycrystalline silicon thin film formed on the surface of the substrate 100. The wavelength to be selected can be set in accordance with.

  The polarization filter 833 adjusts the polarization state of light of a specific wavelength that has passed through the wavelength selection filter 832.

  The imaging lens 834 is for forming an optical image by the first-order diffracted light from the surface of the substrate 100, and the polarization state is adjusted by the polarization filter 833 with the light having a specific wavelength transmitted through the wavelength selection filter 832. An image of the emitted light is formed.

  The image sensor 835 detects an optical image by the first-order diffracted light from the surface of the substrate 100 imaged by the imaging lens 834, and is composed of a CCD (electrically coupled device) one-dimensional sensor or a two-dimensional sensor. ing.

  The substrate stage 850 is configured such that the inspection target substrate 100 is placed on the upper surface and can be moved in the XY plane by the driving means 851.

Outputs from the image sensor 826 of the scattered light imaging optical system 820 and the image sensor 835 of the first-order diffracted light detection optical system 830 are input to the inspection data processing / control unit 740, respectively.
The inspection data processing / control unit 740 converts an analog image signal output from the image sensor 826 of the scattered light image imaging optical system 820 and the image sensor 1165 of the first-order diffracted light detection optical system 830 into a digital image signal. Sections 841 and 843, image processing sections 842 and 844 for processing the respective digital image signals, defect determination section 845 for processing the respective digital image signals subjected to the image processing and determining defects from the image feature amounts, and the determined defects The input / output unit 846 provided with the display screen 847 for outputting the information, the image processing units 842 and 844, the defect determination unit 845, the input / output unit 846, the light source 800, the image sensors 826 and 835, and the drive unit of the substrate stage 850 A control unit 848 for controlling 851 is provided. The control unit 848 is connected to the overall control unit 750 shown in FIG.
FIG. 8B shows a configuration in which the illumination optical system 800 is arranged on the surface side of the substrate 100 as a modification. When the illumination optical system 800 and the first-order diffracted light detection optical system 830 and the scattered light detection optical system 820 do not mechanically interfere with each other, the illumination optical system 800 is moved to the substrate 100 for the first time as shown in FIG. 8B. The folded light detection optical system 830 and the scattered light detection optical system 820 may be disposed on the same side.

  Since the configuration shown in FIG. 8B is different only in the arrangement of the illumination optical system 800, detailed description thereof is omitted.

  With the configuration shown in FIG. 8A or 8B, the illumination optical system 800 irradiates the substrate 100 placed on the substrate stage 850 in a direction so that the incident angle of illumination light is θ1 from the back side of the substrate 100. The imaging optical system 820 captures an image of scattered light around the direct light from the light source 801 that has passed through the illuminated substrate 100, and the image of the first-order diffracted light generated from the illuminated substrate 100 is a first-order diffracted light image. Images are picked up by the detection optical system 830, and the respective picked-up image data are processed by the inspection data processing / control unit 740 to inspect the crystal state of the polycrystalline silicon thin film formed on the substrate 100.

  Next, a method for inspecting the state of the polycrystalline silicon thin film that has been annealed by the excimer laser on the substrate 100 and polycrystallized by the inspection unit 721 and the inspection data processing / control unit 740 having the configuration shown in FIG. 8A will be described. To do.

First, before performing the inspection, optical conditions are set using the substrate 100 on which a polycrystalline silicon thin film has been formed in advance. The optical conditions to be set are the illumination wavelength by the wavelength filter 804 of the illumination optical system 800, the polarization condition by the polarization filter 805, the detection wavelength by the wavelength filter 823 of the scattered light imaging optical system 820, and the polarization condition of the detection light by the polarization filter 824. The image formation position of the scattered light image by the imaging lens 825. These conditions are that a scattered light image obtained by observing the substrate 100 illuminated by the illumination optical system 800 with the scattered light image pickup optical system 820 and a first order diffracted light image obtained by picking up the image with the first order diffracted light detection optical system 830. Are displayed on the display screen 847 of the input / output unit 846 while adjusting so that a scattering structure with high contrast and a first-order diffracted light image can be obtained.
Next, the flow of processing for inspecting the inspection region of the polycrystalline silicon thin film formed by the excimer laser annealing on the substrate 100 under the set optical conditions will be described. The inspection processing includes an imaging sequence for imaging a predetermined region or the entire surface of the substrate, and an image processing sequence for processing an image obtained by imaging and detecting a defective portion.

First, the imaging sequence will be described with reference to FIG.
First, the control unit 846 controls the drive unit 851 of the substrate stage 850 so that the inspection start position of the inspection region of the polycrystalline silicon thin film falls within the field of view of the imaging optical system 820, and the substrate 100 is moved to the initial position (inspection start position). ) Is set (S901).

  Next, the illumination optical system 800 illuminates the polycrystalline silicon thin film (S902), and is driven by the control unit 847 so that the imaging area of the imaging optical system 820 moves along the inspection area of the illuminated polycrystalline silicon thin film. The unit 851 is controlled to start moving the substrate stage 850 at a constant speed (S903).

  Taking a first-order diffracted light image of a first-order diffracted light image generated by illumination light transmitted through a long inspection region in one direction illuminated by the illumination optical system 800 while moving the substrate stage 850 at a constant speed An image of the reflected light scattered light near the optical axis of the transmitted light (reflected light in the configuration of FIG. 8B) picked up by the optical system 830 is picked up by the imaging optical system 820 (S904). An analog signal is output from the image sensor 826 of the scattered light image capturing optical system 820 and input to the A / D converter 841 of the inspection data processing / control unit 740. An analog signal is output from the image sensor 835 of the first-order diffracted light imaging optical system 830 and input to the A / D converter 843 of the inspection data processing / control unit 740. The digital signal converted by the A / D conversion unit 841 is input to the image processing unit 842 and a digital image signal is created using the positional information of the substrate stage 850 obtained through the control unit 848, and A / D conversion is performed. The digital signal converted by the unit 843 is input to the image processing unit 844, and a digital image signal is created and processed using the position information of the substrate stage 850 obtained through the control unit 848 (S905). The above operation is repeated until the inspection area for one line is completed (S906).

  Next, it is checked whether or not there is an inspection area adjacent to the inspected area for one line (S907). If there is an adjacent inspection area, the substrate stage 850 is moved to the adjacent inspection area ( Steps S908) and S904 to S907 are repeated. When all the areas to be inspected have been inspected, the movement of the substrate stage 850 is stopped (S909), the illumination is turned off (S910), and the imaging sequence is ended.

  Next, a detailed sequence of the step (S905) of creating and processing the obtained digital image in the imaging sequence of FIG. 9 will be described with reference to FIG.

  9, the scattered light image is captured by the scattered light image capturing optical system 820 and the analog signal output from the image sensor 826 is input to the A / D conversion unit 841 of the inspection data processing / control unit 740. Then, the digital signal is converted into a digital signal by the A / D conversion unit 841 (S1002), and the converted digital signal of the scattered light image is sent to the image processing unit 842 to generate a digital image signal (S1003). The processed digital image signal of the scattered light image is subjected to preprocessing such as shading correction and averaging processing (S1004), and an image feature amount is extracted (S1005).

  On the other hand, an analog signal output from the image sensor 835 of the first-order diffracted light image detection optical system 830 that detects an image of the first-order diffracted light generated from the substrate 100 illuminated by the illumination optical system 800 is used as an inspection data processing / control unit 740. The digital signal is input to the A / D conversion unit 843 (S1011), converted into a digital signal by the A / D conversion unit 843 (S1012), and the converted digital signal of the first-order diffracted light image is sent to the image processing unit 844 to be a digital image. A signal is generated (S1013), and the generated digital image signal of the first-order diffracted light image is subjected to preprocessing such as shading correction and averaging processing (S1014), and image features such as pattern pitch and luminance of the first-order diffracted light image The amount is extracted (S1015). The scattered light digital image signal from which the image feature amount has been extracted and the digital image signal of the first-order diffracted light image are input to the defect determination unit 845 together with the extracted image feature amount information and integrated (S1021).

  In the defect determination unit 845, defect determination is performed by comparing the image feature amount of each image (for example, a signal obtained by adding the luminance value of one line scan for each pixel) with preset reference data (threshold value). Processing is performed (S1022). In this defect determination process, the principle described with reference to FIGS. 4 to 6 as to whether the region that is smaller than the threshold value and determined as a defect is due to insufficient laser annealing power or excessive power. Can be determined based on

  The digital image data including the determined defect is sent to the input / output unit 846, and the image of the scattered light is displayed on the display unit 847 together with the position information on the substrate 100 (S1023), and the image processing sequence is completed. On the image of the scattered light displayed on the display unit 847, an area determined as a defect by the defect determination unit 845 is displayed so as to be distinguished from a normal area. In addition, when the defect determination criterion is changed by inputting from the input / output unit 846, the defect area is also changed and displayed corresponding to the changed defect determination criterion.

  By inspecting with the above-described configuration, according to the first embodiment, the crystal state of the polycrystalline silicon thin film formed by annealing with the excimer laser can be inspected with relatively high accuracy, and the glass substrate for organic EL Alternatively, the quality of the glass substrate for liquid crystal display can be maintained high.

  In the first embodiment, the configuration in which the wavelength filter and the polarization filter are provided in each of the illumination optical system 800, the scattered light image pickup optical system 820, and the first-order diffracted light image detection optical system 830 has been described. Is not necessarily required for all the optical systems. For example, the illumination optical system 800 may be provided with a wavelength filter and a polarization filter, or the scattered light image pickup optical system 820 and the first-order diffracted light image detection optical system 830 A configuration may be adopted in which a wavelength filter and a polarizing filter are provided. Further, only one of the wavelength filter and the polarization filter may be used.

  Further, the configuration in which the cylindrical lens 805 is used for the illumination optical system 800 to illuminate a long region in one direction on the substrate 100 has been described, but the same effect can be obtained even if this is replaced with a normal circular lens.

  A second embodiment of the present invention will be described with reference to FIGS. 11A and 11B.

  The configuration of the second embodiment shown in FIG. 11A is the same as that of the first embodiment described with reference to FIG. 8A, and the illumination light emitted from the illumination optical system 800 by the scattered light image capturing optical system 1120 of the inspection unit 1110. Are different from each other in that they are installed to be inclined with respect to the optical axis of the transmitted light transmitted through the substrate 100.

  The scattered light image capturing optical system 1120 according to the second embodiment includes an objective lens 1121, a wavelength selection filter 1122, a polarization filter 1123, an imaging lens 1124, and an image sensor 1125, which are housed in a lens barrel 1126.

  By arranging the scattered light image capturing optical system 1120 to be inclined with respect to the transmitted optical axis, the traveling direction of the transmitted light transmitted through the substrate 100 is shifted from the optical axis of the scattered light image capturing optical system 1120, so The image sensor 1125 detects an image of scattered light near the transmitted light.

  That is, in the scattered light image capturing optical system 1120 in the second embodiment, it is not necessary to provide the light shielding plate 821 of the scattered light image capturing optical system 820 described in the first embodiment. The light receiving surface of the lens 822 can be made large. As a result, the amount of scattered light detected by the image sensor 1125 can be increased, so that the detection sensitivity can be improved.

  In the configuration shown in FIG. 11A, the signals output from the scattered light image capturing optical system 1120 and the first-order diffracted light image capturing optical system 830 are input to the A / D converters 1141 and 1143 of the inspection data processing / control unit 1140, respectively. Are converted into digital signals, image processed by the image processing units 1142 and 1144, respectively, sent to the defect determination unit 1145, and defect determination is performed from the image feature amount, and information on the determined defect is output from the input / output unit 1146. .

  Of the configuration shown in FIG. 11A, the configuration other than the scattered light imaging optical system 1120 is the same as the configuration shown in FIG. 8A described in the first embodiment including the inspection data processing / control unit 1140. Detailed description is omitted.

  11A shows an example in which the scattered light image pickup optical system 1120 is tilted to the lower side of the drawing with respect to the traveling direction of the transmitted light. The same effect can be obtained by tilting in a direction perpendicular to the direction.

  FIG. 11B corresponds to the configuration described in FIG. 8B of the first embodiment, and the scattered light image pickup optical system 1120 is installed to be inclined with respect to the traveling direction of the reflected light, as in FIG. 11A. The point is different.

  Since the operation of each part in the configuration shown in FIG. 11B is the same as that described in FIG. 8B of the first embodiment, the description thereof is omitted. In the case of FIG. 11B, similar to the case of FIG. 11A, the same effect can be obtained even when the scattered light image capturing optical system 1120 is tilted upward or laterally (in a direction perpendicular to the paper surface) with respect to the traveling direction of the reflected light. be able to.

  According to the first and second embodiments, the polycrystalline silicon thin film is illuminated to pick up an image of diffracted light generated by the unevenness of the film surface, and by processing the image of the diffracted light obtained by picking up the polycrystalline silicon thin film, It is possible to provide a method and an apparatus for evaluating the crystal state of a thin film.

  As mentioned above, although the invention made by the present inventor has been specifically described based on the embodiments, it is needless to say that the present invention is not limited to the above embodiments and can be variously modified without departing from the gist thereof. Yes.

  DESCRIPTION OF SYMBOLS 100 ... Board | substrate 700 ... Inspection apparatus 720 ... Inspection part 721 ... Inspection unit 740 ... Inspection data processing / control part 750 ... Overall control part 800, 1100 ... Illumination optical system 820 , 1120 ... Imaging optical system 850, 1150 ... Stage unit 1160 ... First-order diffracted light detection optical system.

Claims (12)

A light irradiating means for irradiating light onto a substrate having a polycrystalline silicon thin film formed on the surface;
An image of scattered light from the polycrystalline silicon thin film in the vicinity of light transmitted through the polycrystalline silicon thin film or reflected by the polycrystalline silicon thin film out of the light irradiated to the substrate by the light irradiation means is taken. First imaging means;
A second image pickup means for picking up an image of first-order diffracted light generated from the polycrystalline silicon thin film irradiated with light by the light irradiation means;
The state of the crystal of the polycrystalline silicon thin film by processing the image of the scattered light obtained by imaging with the first imaging means and the image of the first-order diffracted light obtained by imaging with the second imaging means Image processing means for inspecting
An inspection apparatus for a polycrystalline silicon thin film characterized by comprising:   The first imaging means includes a light shielding plate that shields light transmitted through the polycrystalline silicon thin film or light reflected by the polycrystalline silicon thin film, and the polycrystalline silicon thin film not shielded by the light shielding plate 2. The inspection apparatus for a polycrystalline silicon thin film according to claim 1, wherein an image of scattered light from the polycrystalline silicon thin film in the vicinity of light that has passed through or reflected by the polycrystalline silicon thin film is captured.   The first imaging means is reflected by the light transmitted through the polycrystalline silicon thin film or the polycrystalline silicon thin film so that light transmitted through the polycrystalline silicon thin film or light reflected by the polycrystalline silicon thin film is not detected. 2. The polycrystalline silicon thin film inspection apparatus according to claim 1, wherein the inspection apparatus is installed to be inclined with respect to the light traveling direction.   The light irradiation unit irradiates the light from the back side of the substrate, and the imaging unit irradiates the back side of the substrate by the light irradiation unit and scatters the scattered light from the surface side of the polycrystalline silicon thin film. 4. The polycrystalline silicon thin film inspection apparatus according to claim 1, wherein:   The light irradiation means irradiates the light from the surface side of the substrate, and the imaging means scatters light scattered from the surface side of the polycrystalline silicon thin film by the light irradiated to the surface side of the substrate by the light irradiation means. The polycrystalline silicon thin film inspection apparatus according to claim 1, wherein an image of the above is taken.   The light irradiating unit includes a wavelength selecting unit and irradiates the substrate with light having a wavelength selected by the wavelength selecting unit, and the first imaging unit includes a polarization filter for transmitting or reflecting light from the substrate. 6. The polycrystalline silicon thin film inspection apparatus according to claim 1, wherein a first-order diffracted light image is picked up by light transmitted through the polarizing filter among scattered light in the vicinity. Irradiate the substrate with a polycrystalline silicon thin film on the surface,
Taking an image of scattered light from the polycrystalline silicon thin film in the vicinity of light transmitted through the polycrystalline silicon thin film or light regularly reflected by the polycrystalline silicon thin film among the light irradiated on the substrate,
Taking an image of the first-order diffracted light generated from the polycrystalline silicon thin film by the light irradiated on the substrate,
Processing the image obtained by taking the image of the scattered light and the image obtained by taking the image of the first-order diffracted light to inspect the crystal state of the polycrystalline silicon thin film;
A method for inspecting a polycrystalline silicon thin film.   Capturing an image of scattered light from the polycrystalline silicon thin film in the vicinity of the light transmitted through the polycrystalline silicon thin film or the light regularly reflected by the polycrystalline silicon thin film, or the light transmitted through the polycrystalline silicon thin film or The light regularly reflected by the polycrystalline silicon thin film is shielded, and the light transmitted through the polycrystalline silicon thin film that is not shielded by the light shielding or the light reflected by the polycrystalline silicon thin film is near the polycrystalline silicon thin film. The method for inspecting a polycrystalline silicon thin film according to claim 7, wherein an image of the scattered light is picked up.   Capturing an image of scattered light from the polycrystalline silicon thin film in the vicinity of light transmitted through the polycrystalline silicon thin film or light regularly reflected by the polycrystalline silicon thin film among the light irradiated on the substrate, The light transmitted through the polycrystalline silicon thin film or the light reflected by the polycrystalline silicon thin film is tilted with respect to the traveling direction of the light transmitted through the polycrystalline silicon thin film or reflected by the polycrystalline silicon thin film so that the light is not detected. 8. The method for inspecting a polycrystalline silicon thin film according to claim 7, wherein imaging is performed.   Irradiating the substrate with light, irradiating light from the back surface side of the substrate, and capturing the image of the scattered light was irradiated on the back surface side of the substrate and scattered from the front surface side of the polycrystalline silicon thin film. 10. The method for inspecting a polycrystalline silicon thin film according to claim 7, wherein the inspection is performed by taking an image of scattered light.   Irradiating light to the substrate from the surface side of the substrate and irradiating the surface side of the substrate to irradiate light from the surface side of the substrate and scattering from the surface side of the polycrystalline silicon thin film 10. The method for inspecting a polycrystalline silicon thin film according to claim 7, wherein the inspection is performed by taking an image of scattered light in the vicinity of specularly reflected light from the substrate among scattered light.   The light applied to the substrate is light having a selected wavelength, and the scattered light in the vicinity of transmitted light or reflected light from the substrate to be imaged is an image of scattered light by light transmitted through a polarizing filter. The method for inspecting a polycrystalline silicon thin film according to any one of claims 7 to 11.

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