JP5201185B2 - Observation optical system and laser processing apparatus - Google Patents

Description

  The present invention relates to an observation optical system and a laser processing apparatus, and more particularly, to an observation optical system and a laser processing apparatus that can favorably observe a mark for positioning an object and a light and shade pattern.

  Conventionally, a bright field optical system has been used as an observation optical system used for observing a positioning alignment mark provided on an object such as a substrate. However, in the conventional bright-field optical system, the alignment mark signal light included in the reflected light from the object is smaller than other noise lights, and the alignment mark may be observed only with low contrast.

  Therefore, a dark field optical system that can observe the alignment mark with high contrast may be used (for example, see Patent Document 1).

JP-A-8-306609

  However, in the conventional dark field optical system, a region where the scattered light of the object does not occur (hereinafter, referred to as a non-scattering region) such as a smooth flat surface becomes dark, and the grayscale pattern in that region cannot be observed. . Therefore, in order to observe the shading pattern in the non-scattering region, the optical system to be used must be switched from the dark field optical system to the bright field optical system.

  The present invention has been made in view of such a situation, and makes it possible to satisfactorily observe both the alignment mark and the shading pattern of the object.

  An observation optical system according to a first aspect of the present invention is an observation optical system for observing a mark for positioning an object, and forms an objective lens and illumination light emitted from a light source at the pupil of the objective lens. A condensing lens, an imaging lens that forms an image of reflected light from the object irradiated with the illumination light through the objective lens and transmitted through the objective lens, and the collecting lens; Branch means for branching the optical path of the illumination light and the reflected light between the optical lens and the objective lens, and between the objective lens and the imaging lens, λ the wavelength of the illumination light, and the positioning When the width of the narrowest part of the mark is w, the illumination light that is provided between the condenser lens and the branching unit and is incident within a numerical aperture of less than about 2λ / w of the objective lens A light blocking means for blocking, and said And at least one of light blocking means provided between the branching means and the objective lens for blocking the reflected light that enters the numerical aperture of the objective lens within a numerical aperture of less than about 2λ / w.

  In the observation optical system according to the first aspect of the present invention, illumination light is imaged at the pupil of the objective lens, irradiated onto the object through the objective lens, and reflected light from the object is transmitted through the objective lens. Then, an image is formed by an imaging lens. In addition, illumination light or reflected light that enters within the numerical aperture range of less than about 2λ / w of the objective lens is blocked.

  Therefore, it is possible to satisfactorily observe both the mark for positioning the object and the shading pattern. In addition, the positioning accuracy of the object is improved and the positioning time is shortened.

  This light source is comprised by LED, for example. This branching means is constituted by, for example, a half mirror. This light shielding means is constituted by, for example, a light shielding body made of a metal plate or a light shielding body in which a light shielding film is formed on a glass plate.

  The light shielding means may have a light shielding region having substantially the same shape as the section of the illumination light.

  Thereby, the nonuniformity of the illumination light irradiated to a target object can be eliminated.

  This illumination light can be monochromatic light.

  Thereby, the mark for positioning can be observed more clearly.

  A laser processing apparatus according to a second aspect of the present invention includes an observation optical system for observing a mark for positioning an object, and a processing optical system for irradiating the object with a processing laser beam. In the laser processing apparatus, the observation optical system includes a light source that emits illumination light, an objective lens, a condensing lens that forms an image of the illumination light on a pupil of the objective lens, and the illumination light that passes through the objective lens. An imaging lens that forms an image of the reflected light from the irradiated object after passing through the objective lens, between the condenser lens and the objective lens, and the objective lens Between the imaging lenses, a branching unit that branches the optical path of the illumination light and the reflected light, a wavelength of the illumination light is λ, and a width of the narrowest portion of the positioning mark is w, Condensing lens and branching means A light blocking means for blocking the illumination light incident within a numerical aperture of less than about 2λ / w of the objective lens, and provided between the branching means and the objective lens, And at least one of light shielding means for blocking the reflected light incident within a numerical aperture range of less than about 2λ / w.

  Therefore, it is possible to satisfactorily observe both the mark for positioning the object and the shading pattern. In addition, the positioning accuracy of the object is improved and the positioning time is shortened. As a result, the processing accuracy of laser processing is improved and the processing time is shortened.

  This light source is comprised by LED, for example. This branching means is constituted by, for example, a half mirror. This light shielding means is constituted by, for example, a light shielding body made of a metal plate or a light shielding body in which a light shielding film is formed on a glass plate.

  This laser beam can be applied to the object through the objective lens.

  Thereby, the objective lens of the observation optical system and the processing optical system can be shared, and the number of parts can be reduced.

  According to the first aspect or the second aspect of the present invention, it is possible to satisfactorily observe both the mark for positioning the object to be observed and the light and shade pattern.

It is a block diagram which shows one Embodiment of the laser processing apparatus to which this invention is applied. It is a figure which shows the 1st example of a light-shielding body. It is a figure which shows the 2nd example of a light-shielding body. It is a figure which shows the 3rd example of a light-shielding body. It is a figure which shows the 4th example of a light-shielding body. It is a figure which shows the example of an alignment mark. It is a figure for demonstrating the conditions which make an alignment mark observable. It is a graph which shows the example of the OTF characteristic of an objective lens. It is a graph which shows the example of the OTF characteristic except the center area | region of the objective lens. It is a figure for demonstrating the effect of a laser processing apparatus. It is a figure for demonstrating the effect of a laser processing apparatus. It is a figure for demonstrating the effect of a laser processing apparatus. It is a figure for demonstrating the effect of a laser processing apparatus. It is a figure for demonstrating the effect of a laser processing apparatus. It is a figure which shows the example of the cross section of illumination light. It is a figure which shows the example of the cross section of the illumination light after permeate | transmitting a condensing lens. It is a figure which shows the example of the cross section of the illumination light after passing through the light shielding body which has a circular light shielding area. It is a figure which shows the example of the cross section of the illumination light after passing through the light shielding body which has a rectangular light shielding area. It is a figure which shows the 5th example of a light-shielding body. It is a figure which shows the 6th example of a light-shielding body.

Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described. The description will be given in the following order.
1. Embodiment 2. FIG. Modified example

<1. Embodiment>
[Configuration example of laser processing equipment]
FIG. 1 is a diagram showing an embodiment of an optical system of a laser processing apparatus 101 to which the present invention is applied.

  The laser processing apparatus 101 is an apparatus that performs laser processing on an object to be processed such as a substrate. Hereinafter, the solar cell panel 102 will be described as an example of the processing object.

  The optical system of the laser processing apparatus 101 includes a laser oscillator 111, a beam expander 112, a slit 113, an imaging lens 114, a dichroic mirror 115, an objective lens 116, an illumination device 117, a condensing lens 118, a light shield 119, and a half mirror 120. And an imaging lens 121 and a CCD (Charge Coupled Device) camera 122. Among them, the laser oscillator 111, the beam expander 112, the slit 113, the imaging lens 114, the dichroic mirror 115, and the objective lens 116 constitute a processing optical system for irradiating the solar cell panel 102 with processing laser light. Is done. The objective lens 116, the illumination device 117, the condenser lens 118, the light shield 119, the half mirror 120, the imaging lens 121, and the CCD camera 122 constitute an observation optical system for observing the solar cell panel 102. The

  First, the operation of the processing optical system will be described.

  The laser beam emitted from the laser oscillator 111 is collimated and expanded by the beam expander 112, and passes through the slit 113, so that the beam diameter is limited to a predetermined size. The laser light that has passed through the slit 113 is collimated by the imaging lens 114, reflected by the dichroic mirror 115 in the direction of the objective lens 116, and collected by the objective lens 116 on the processing surface of the solar cell panel 102. The laser light is scanned on the processed surface of the solar cell panel 102 by scanning means (not shown) such as a galvanometer mirror. And the processing surface of the solar cell panel 102 is processed by this laser beam.

  Next, the operation of the observation optical system will be described.

  The illumination device 117 includes, for example, a circular light source composed of a single color LED (Light Emitting Diode) having a predetermined wavelength (for example, 0.6 μm). The light source of the present invention can be considered as a surface light source. The illumination light having a circular cross section emitted from the light source of the illumination device 117 is collected by the condenser lens 118, reflected by the half mirror 120 in the direction of the objective lens 116, and imaged at the pupil of the objective lens 116. The Illumination light imaged at the pupil of the objective lens 116 is Fourier transformed by the objective lens 116 and applied to the solar cell panel 102.

  Light reflected by the solar cell panel 102 (hereinafter referred to as reflected light) passes through the objective lens 116, the dichroic mirror 115, the half mirror 120, and the imaging lens 121 and enters the CCD camera 122. At this time, the reflected light is transmitted through the objective lens 116 and then imaged on the light receiving surface of the CCD image sensor (not shown) of the CCD camera 122 by the imaging lens 121. Imaged.

  Further, between the condenser lens 118 and the objective lens 116, a light shield 119 is provided in the vicinity of the condenser lens 118 on the half mirror 120 side. The light shield 119 is obtained by processing a metal plate such as stainless steel, for example, and blocks light in the vicinity of the optical axis of the condenser lens 118 out of illumination light transmitted through the condenser lens 118.

[Configuration example of light shielding body]
Here, with reference to FIG. 2 thru | or FIG. 5, the structural example of the light-shielding body used for the laser processing apparatus 101 is demonstrated. In FIG. 2 to FIG. 5, a light shielding region that blocks incident illumination light is shown by shading.

  The light shielding body 151 in FIG. 2 is provided with a circular light shielding area 151A in the center. In addition, in order to support the light shielding region 151A, the light shielding region 151A and the ring-shaped outer peripheral portion 151B are connected via linear connection portions 151C to 151F. By disposing the center of the light shield 151 so as to coincide with the optical axis of the condenser lens 118, among the illumination light transmitted through the condenser lens 118, a circular light shielding region 151A in the vicinity of the optical axis of the condenser lens 118. The light incident on is blocked.

  In the light shielding body 152 of FIG. 3, a plurality of circular openings of the same size are arranged at equal intervals in a ring shape so as to surround the central, substantially circular light shielding region 152A. By arranging the center of the light shielding body 152 so as to coincide with the optical axis of the condensing lens 118, out of the illumination light transmitted through the condensing lens 118, a substantially circular light shielding region in the vicinity of the optical axis of the condensing lens 118. Light incident on 152A is blocked.

  In addition, in the light shield 151 of FIG. 2, light incident on the connecting portions 151C to 151F is blocked, so that the brightness of the light passing through the light shield 151 varies depending on the direction from the optical axis. The light passing through 152 does not have such brightness variations and has almost uniform brightness.

  The light shield 153 in FIG. 4 and the light shield 154 in FIG. 5 are modifications of the light shield 152 in FIG. In the light shielding body 153 of FIG. 4, a plurality of circular openings of the same size are arranged in a double ring at equal intervals so as to surround the substantially circular light shielding region 153A at the center. In the light shielding body 154 of FIG. 5, a plurality of circular openings are arranged in a double ring at equal intervals so as to surround a substantially circular light shielding region 154A at the center, and the outer opening is on the inner side. It is larger than the opening. In this way, by adjusting the size and arrangement of the circular openings, it is possible to adjust the size and the like of the central light shielding region.

[Light shielding range of light shielding body 119]
Next, the light shielding range of the light shield 119 will be discussed with reference to FIGS.

  FIG. 6 shows an example of an alignment mark 201 provided as a positioning mark on the solar cell panel 102. The alignment mark 201 has a shape in which line segments having a width w (for example, 20 μm), a length l (for example, 120 μm), and a thickness t (for example, 2 μm) are crossed. The alignment mark 201 is formed, for example, by vapor-depositing an aluminum thin film on the glass substrate of the solar cell panel 102 or by partially removing the laminated thin film in the manufacturing process of the solar cell panel 102. . Hereinafter, a case where the alignment mark 201 is formed mainly by vapor deposition will be described.

  In order to observe the alignment mark 201 having the line width w, it is necessary that the observation optical system of the laser processing apparatus 101 has an ability to observe the concavo-convex pattern having the pitch p ≦ w / 2 according to Shannon's information theorem. . This condition will be briefly described with reference to FIG.

  When the pitch p of the diffraction grating 211 in FIG. 7 is p = 2, the diffraction angle of the primary diffraction light of the diffraction grating 211 is α, and the wavelength of the illumination light is λ, the following equation is established.

  sin α = λ / p = 2λ / w (1)

  Therefore, when the numerical aperture (NA) of the objective lens 116 in the air is sin β, it is possible to observe the uneven pattern with the pitch p = w / 2 by setting sin β ≧ sin α = 2λ / w. Note that the angle β is the maximum expected angle of the objective lens 116.

  Further, from the equation (1), the first-order diffraction angle α of the diffraction grating 211 increases as the pitch p decreases, and decreases as the pitch p increases. Accordingly, the light including information on the uneven pattern on the surface of the solar cell panel 102 (having a high spatial frequency) is an angle with respect to the optical axis when viewed from the area around the objective lens 116, that is, the solar cell panel 102 (expected angle). Passes through a large area. On the other hand, the information on the uneven pattern with a rough surface (low spatial frequency) of the solar cell panel 102 passes through a central region of the objective lens 116, that is, a region with a small prospective angle.

  FIG. 8 is a graph showing an example of an optical transfer function (hereinafter referred to as OTF) of the objective lens 116. The horizontal axis represents the spatial frequency (unit: cycle / mm), and the vertical axis represents OTF. A curve 221 represents an OTF curve of the entire objective lens 116, and a curve 222 is a central area (hereinafter referred to as a central area α) of the objective lens 116 where the prospective angle θ <α, in other words, the objective lens. The OTF curve for the region within the numerical aperture range of less than 116 sin α (= 2λ / w) is shown. The OTF curve 222 has a narrower spatial frequency band than the OTF curve 221. Specifically, the OTF curve 222 ranges from 0 to 1 / p (= 2 / w).

  Further, an OTF curve when the central region α of the objective lens 116 is shielded, that is, an OTF curve in a region around the objective lens 116 where the prospective angle θ ≧ α is obtained by subtracting the curve 222 from the curve 221. Specifically, the curve 231 shown in FIG. 9 is obtained. The OTF curve 231 has a characteristic in which the spatial frequency has a peak at 1 / p (= 2 / w).

  Therefore, by shielding the central region α of the objective lens 116, the concave / convex pattern having a spatial frequency of less than 2 / w is attenuated, and the concave / convex pattern having the same pitch as the line width w of the alignment mark 201 is emphasized and observed. it can. As a result, the alignment mark 201 having the line width w can be emphasized and observed.

  Therefore, in the laser processing apparatus 101, a part of the illumination light is blocked by the light shield 119 so that the illumination light does not enter the central region α of the objective lens 116. That is, the illumination light transmitted through the condensing lens 118 is blocked by the light shield 119 in the vicinity of the optical axis and imaged at the pupil of the objective lens 116, and then in an area outside the central area α of the objective lens 116. Incident light is applied to the solar cell panel 102. Therefore, compared with the case where a part of the illumination light is not blocked by the light shield 119, the low-frequency component having a spatial frequency of less than 2 / w is included in the uneven pattern on the observation surface (= processed surface) of the solar cell panel 102. Excited weakly, high frequency components having a spatial frequency of 2 / w or more are excited with substantially the same intensity. As a result, the OTF characteristic of the objective lens 116 becomes substantially the same as that shown in FIG. 9, and the alignment mark 201 can be emphasized and observed.

[Operational effects of laser processing apparatus 101]
Here, with reference to FIG. 10 thru | or FIG. 14, the effect of the laser processing apparatus 101 is demonstrated in more detail.

  As shown in FIG. 10, the illumination light emitted from the objective lens 116 is collected as a substantially parallel wavefront on the observation surface of the solar cell panel 102, and the reflected light reflected by the observation surface is reflected on the objective lens 116. Return.

  11 and 12 are enlarged views of a range 251 near the condensing point surrounded by a dotted line in FIG. FIG. 11 schematically shows a state in which illumination light is incident on the solar cell panel 102 being manufactured, and FIG. 12 schematically shows a state in which the illumination light is reflected on the solar cell panel 102 being manufactured. ing.

  In the example of FIGS. 11 and 12, the solar cell panel 102 is configured by three layers of a layer 102A, a layer 102B, and a layer 102C from the bottom, and a power generation region is formed by the layers 102B and 102C. The layer 102B has a higher reflectance than the layer 102C, and a gray pattern is formed by a region where the layer 102C is formed and a region where the layer 102B appears on the surface without the layer 102C being formed. The wavelength λ of the illumination light is set to a value larger than the step L1 (for example, 0.3 μm) between the layer 102B and the layer 102C.

  In the region where the rightmost layer 102B and layer 102C are not formed, an alignment mark 201 is formed on the upper surface of the layer 102A. The wavelength λ of the illumination light is set to a value smaller than the step L2 (for example, 2.0 μm) between the alignment mark 201 and the layer 102A.

  The illumination light incident at a wavefront parallel to the observation surface of the solar cell panel 102 is modulated on the observation surface of the solar cell panel 102 to become reflected light. Of the reflected light, light and shade information is superimposed on the light reflected on the light and shade pattern formed by the layers 102B and 102C. Since the reflected light on which the grayscale information is superimposed has the step L1 of less than the wavelength λ, as shown in a range 261 surrounded by a dotted line in FIG. Changes. In this figure, the change in amplitude is represented by the thickness of the line. On the other hand, in the reflected light, the light reflected in the vicinity of the alignment mark 201 is superimposed with the unevenness information in addition to the shading information. The reflected light on which the unevenness information is superimposed has a step L2 larger than the wavelength λ, so that the amplitude changes and the reflection angle changes with respect to the incident angle as shown in the range 262 surrounded by the dotted line in FIG. To do.

  This is considered by returning from the near field near the condensing point to the far field near the objective lens 116, and when the incident angle of the illumination light A1 is θi and the reflection angle of the reflected light B1 is θo as shown in FIG. When only the density information is superimposed on the observation surface of the solar cell panel 102 and the unevenness information is not superimposed, the incident angle θi = the reflection angle θo. On the other hand, when unevenness information is superimposed on the observation surface of the solar cell panel 102, the incident angle θi is not equal to the reflection angle θo.

  In the conventional dark field optical system, the reflected light on which only the density information is superimposed, where the incident angle θi = the reflection angle θo, passes through the outside of the objective lens or is interrupted and is not observed. On the other hand, a part of the reflected light on which the concave / convex information is superimposed, where the incident angle θi ≠ the reflection angle θo, is incident on the objective lens and is observed without being interrupted. Therefore, if the conventional dark field optical system is used, the uneven pattern on the observation surface of the solar cell panel 102 can be observed with a high SNR, and the alignment mark 201 can also be observed with a high SNR. On the other hand, the shading pattern on the observation surface of the solar cell panel 102 cannot be observed.

  In the conventional bright field optical system, a part of the reflected light on which only the grayscale information is superimposed and the reflected light on which the unevenness information is superimposed are incident on the objective lens and observed. Therefore, if the conventional bright-field optical system is used, both the shading pattern and the uneven pattern on the observation surface of the solar cell panel 102 can be observed. On the other hand, the SNR of the concavo-convex pattern on the observation surface of the solar cell panel 102 is lowered, and the alignment mark 201 cannot be observed with a high SNR compared to the dark field optical system.

  On the other hand, in the laser processing apparatus 101, regardless of whether or not the reflection angle θo is different from the incident angle θi, the reflected light is incident on the objective lens 116 and observed if α ≦ θo ≦ β. it can. For example, in the example of FIG. 14, both the reflected light B11 having the same reflection angle θo and the reflected light B12 having a different reflection angle θo with respect to the incident light A11 are incident on the objective lens 116 and can be observed. Therefore, it is possible to observe both the shading pattern and the uneven pattern on the observation surface of the solar cell panel 102.

  Note that light such as the reflected light B13 having a reflection angle θo> β in FIG. 14 does not enter the objective lens 116, and thus cannot be observed as in the conventional dark field optical system and bright field optical system.

  In addition, since the illumination light does not enter the central region α indicated by the oblique lines in FIG. 14, the reflected light with the reflection angle θo ≦ α is substantially reduced. Therefore, a component lower than the spatial frequency corresponding to the line width w of the alignment mark 201 in the uneven pattern on the observation surface of the solar cell panel 102 can be attenuated. Therefore, the alignment mark 201 can be observed with high SNR.

  Furthermore, for example, when the alignment mark 201 is formed by removing a part of the thin film of the solar cell panel 102, a shading pattern by laser processing may be formed in the alignment mark 201. In the laser processing apparatus 101, such a shading pattern in the alignment mark 201 can be observed, and as a result, the alignment mark 201 can be observed more clearly.

  As described above, the laser processing apparatus 101 can favorably observe both the alignment mark 201 and the shading pattern of the solar cell panel 102. In addition, since the alignment mark 201 can be observed well, the positioning accuracy of the solar cell panel 102 can be improved and the time required for positioning can be shortened. As a result, the processing accuracy of the solar cell panel 102 is improved and the processing time can be shortened.

<2. Modification>
In the above description, the example in which the light shield 119 is provided between the condenser lens 118 and the half mirror 120 has been described. However, more strictly, the half mirror 120 and the dichroic mirror are provided between the half mirror 120 and the objective lens 116. A light blocking body may be provided between the light source 115 and the illumination light incident on the central region α of the objective lens 116. As a result, the OTF characteristic of the objective lens 116 is substantially the same as that shown in FIG. As a result, as in the above-described embodiment, both the shading pattern and the uneven pattern of the solar cell panel 102 can be observed, and the alignment mark 201 can be observed with emphasis.

  In this case, not only the illumination light incident on the central region α but also the light passing through the vicinity of the optical axis of the objective lens 116 among the reflected light from the solar cell panel 102 can be blocked. Therefore, it is possible to block more components lower than the spatial frequency corresponding to the line width w of the alignment mark 201 in the uneven pattern on the observation surface of the solar cell panel 102, and to observe the alignment mark 201 with more emphasis. Is possible.

  In the above description, an example in which a circular light source is provided in the lighting device 117 has been described, but a light source having another shape may be provided. For example, as shown in FIG. 15, a light source that emits illumination light having a rectangular cross section may be provided. However, in this case, as described below, it is desirable that the shape of the light shielding region of the light shielding body is not circular but rectangular.

  FIG. 16 shows an example of the shape of the cross section after the illumination light having the cross section shown in FIG. The cross section of the illumination light after passing through the condenser lens 118 has a slightly rounded corner as compared with the cross section of the illumination light in the illumination device 117.

  FIG. 17 shows the light shielding region and the light shielding when the illumination light shown in FIG. 16 is shielded by using a light shielding body having a substantially circular light shielding region as described above with reference to FIGS. An example of a region that is not performed is shown. In addition, the area | region shown with a shade in the figure has shown the area | region where light shielding is carried out. As shown in this figure, when illumination light having a substantially rectangular cross section is shielded by a circular light shielding region, the brightness of the illumination light after passing through the light shield varies depending on the position. That is, the closer to the four corners of the cross section of the illumination light, the more illumination light passes through the light shielding body, and the further away from the four corners, the less illumination light passes through the light shielding body. Therefore, the brightness of the illumination light becomes brighter as it approaches the four corners of the cross section, and becomes darker as it moves away from the four corners. As a result, unevenness occurs in the brightness of the illumination light applied to the solar cell panel 102.

  Therefore, as shown in FIG. 18, it is desirable to block the rectangular area at the center of the illumination light in accordance with the cross section of the illumination light.

  FIG. 19 and FIG. 20 are diagrams illustrating an example of a light shielding body that shields a central rectangular area of illumination light. In the light shielding body 301 of FIG. 19, a rectangular light shielding region 301A is provided in the center. Further, in order to support the light shielding region 301A, the corners of the light shielding region 301A and the ring-shaped outer peripheral portion 301B are connected by linear support members 301C to 301F. Similarly to the light shield 301, the light shield 311 in FIG. 20 is also provided with a rectangular light shield region 311A at the center. Further, in order to support the light shielding region 311A, the central portion of each side of the light shielding region 311A and the ring-shaped outer peripheral portion 311B are connected by linear support members 311C to 311F.

  By arranging the center of the light shielding body 301 or the light shielding body 311 so as to coincide with the optical axis of the condensing lens 118, out of the illumination light transmitted through the condensing lens 118, a rectangle near the optical axis of the condensing lens 118 is obtained. The light incident on the light shielding region 301A or the light shielding region 311A is blocked.

  Thus, it is desirable that the shape of the light shielding region of the light shielding body is substantially the same as the shape of the cross section of the illumination light.

  In the above description, the example in which the light shielding member 119 is formed of a metal plate has been described. However, for example, a light shielding member in which a light shielding region such as a light shielding film is formed on a transparent member such as glass may be used. Further, a light shielding film may be directly formed on the objective lens 116 or the condenser lens 118.

  Moreover, although the example which applies this invention to the laser processing apparatus 101 was shown in the above description, this invention is applicable to the whole apparatus which positions a target object based on an alignment mark. Furthermore, the object to be observed according to the present invention is not limited to the solar cell panel 102, and various kinds of substrates on which alignment marks are provided can be used as objects.

  In the above description, an example in which an LED is used as the light source of the lighting device 117 has been described. However, other types of light sources may be used.

  In the above description, the example in which the illumination light is monochromatic light has been described. However, illumination light having a predetermined wavelength width may be used. In this case, as the wavelength λ of the illumination light used in the above-described formula (1) and the like, a representative wavelength of the illumination light, for example, a peak wavelength, a center wavelength, a maximum wavelength, and the like may be used. For example, when white light is used as illumination light, it is conceivable to use a central green wavelength (546.1 nm).

  Note that the alignment mark can be observed more clearly when the illumination light is monochromatic light. On the other hand, when the illumination light is white light, not only the density pattern of the object but also the color of the object can be observed.

  Furthermore, in the above description, an example in which the shape of the alignment mark is a cruciform shape is shown, but the present invention is not limited to this example, and an arbitrary shape can be adopted. When the alignment mark has a shape other than the cross shape, for example, the width of the narrowest portion of the alignment mark is used as the width w used in the above-described equation (1).

  In the above description, the direction of the illumination light is changed by the half mirror 120 to branch the optical path of the illumination light from the illumination device 117 to the half mirror 120 and the optical path of the reflected light from the half mirror 120 to the CCD camera 122. However, the two light paths may be branched by changing the direction of the reflected light or changing the directions of both the illumination light and the reflected light.

  Further, the laser oscillator 111, the illumination device 117, and the CCD camera 122 can be externally attached to the outside of the laser processing device 101, separately from the laser processing device 101.

  The embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 101 Laser processing apparatus 102 Solar cell panel 111 Laser oscillator 112 Beam expander 113 Slit 114 Imaging lens 115 Dichroic mirror 116 Objective lens 117 Illumination apparatus 118 Condensing lens 119 Light-shielding body 120 Half mirror 121 Imaging lens 122 CCD camera 151 to 154 Light shielding body 151A to 154A Light shielding area 201 Alignment mark 301 Light shielding body 301A Light shielding area

Claims (5)

In the observation optical system for observing the mark for positioning the object,
An objective lens;
A condenser lens that forms an image of illumination light emitted from a light source at the pupil of the objective lens;
An imaging lens that forms an image of the reflected light from the object irradiated with the illumination light through the objective lens and transmitted through the objective lens;
Branch means for branching the optical path of the illumination light and the reflected light between the condenser lens and the objective lens and between the objective lens and the imaging lens;
When the wavelength of the illumination light is λ, and the width of the narrowest portion of the positioning mark is w, the aperture is provided between the condenser lens and the branching unit and is less than about 2λ / w of the objective lens. A light shielding means for blocking the illumination light incident within a range of numbers, and the light incident between the branching means and the objective lens and incident within a numerical aperture of less than about 2λ / w of the objective lens An observation optical system comprising: at least one of light shielding means for blocking reflected light. The observation optical system according to claim 1, wherein the light shielding unit includes a light shielding region having substantially the same shape as a section of the illumination light. The observation optical system according to claim 1, wherein the illumination light is monochromatic light. In a laser processing apparatus comprising: an observation optical system for observing a mark for positioning an object; and a processing optical system for irradiating the object with laser light for processing;
The observation optical system is
A light source that emits illumination light;
An objective lens;
A condenser lens that forms an image of the illumination light at the pupil of the objective lens;
An imaging lens that forms an image of the reflected light from the object irradiated with the illumination light through the objective lens and transmitted through the objective lens;
Branch means for branching the optical path of the illumination light and the reflected light between the condenser lens and the objective lens and between the objective lens and the imaging lens;
When the wavelength of the illumination light is λ, and the width of the narrowest portion of the positioning mark is w, the aperture is provided between the condenser lens and the branching unit and is less than about 2λ / w of the objective lens. A light shielding means for blocking the illumination light incident within a range of numbers, and the light incident between the branching means and the objective lens and incident within a numerical aperture of less than about 2λ / w of the objective lens A laser processing apparatus comprising: at least one of light shielding means for blocking reflected light. The laser processing apparatus according to claim 4, wherein the laser beam is applied to the object through the objective lens.

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