JP4220571B1 - Minute height measuring device - Google Patents

Abstract

An optical configuration of an apparatus is simplified.
A white light source 2 that irradiates a pinhole member 3 having a plurality of pinholes with white light L1 and a white light L1 that is provided opposite to the object to be measured 11 and passes through the pinhole is measured. An objective lens 4 that condenses on the light 11, an imaging means 6 that includes a plurality of light receiving elements and receives the reflected light L 2 from the DUT 11 of the white light L 1 that has passed through the pinhole, and the objective lens 4. Displacement means 10 for displacing the distance between the object to be measured 11 is provided.
[Selection] Figure 1

Description

  The present invention relates to a minute height measuring apparatus for measuring a minute height of a protrusion or the like on an object to be measured, and particularly relates to a minute height measuring apparatus using a pinhole.

A conventional minute height measuring device radiates measurement light to irradiate a Nippon disk that has a plurality of pinholes and irradiates measurement light that is provided opposite to the object to be measured and passes through the pinhole. An objective lens for focusing on the object to be measured; an imaging means for receiving reflected light from the object to be measured that has passed through the pinhole through the pinhole; and the objective lens is displaced in the direction of the optical axis. Displacement means to be provided (see, for example, Patent Document 1).
JP 2004-177173 A

  However, such a conventional minute height measuring device receives the reflected light from the object to be measured that has passed through the pinhole of the Nippon disk through the same pinhole. An optical system for uniformly irradiating light on the Nippon disk, and an image for forming an image of the pinhole on the light receiving surface of an image pickup means provided on the optical path branched from the optical path of the optical system There is a problem that the optical configuration of the apparatus becomes complicated because it is necessary to provide an optical system behind the Nippon disk.

  Accordingly, an object of the present invention is to provide a minute height measuring apparatus that addresses such problems and simplifies the optical configuration of the apparatus.

In order to achieve the above object, a minute height measuring apparatus according to the present invention includes a measurement light source for irradiating measurement light to a pinhole member in which a plurality of pinholes are formed, and the pin provided to face the object to be measured. An objective lens that condenses the measurement light that has passed through the hole on the object to be measured, and an optical path that is branched from an optical path from the objective lens toward the pinhole member. imaging means for directly receiving the reflected light from the measurement point the measurement light passing through the hole is specified by irradiating onto the object to be measured, the displacement means for displacing the distance between the measured object and the objective lens And a plurality of light receiving elements of the imaging means for receiving reflected light from a measurement point on the measurement object designated by measurement light that has passed through any one pinhole of the pinhole member The most And selects the output from one of the light receiving element showed a high detection output as an output from the light receiving element corresponding to the measurement point.

With such a configuration, the pinhole member in which a plurality of pinholes is formed is irradiated with the measurement light by the measurement light source, and the measurement light that has passed through the pinhole is covered by the objective lens that is provided facing the object to be measured. focused on the measurement object, the optical path toward the pinhole member from the objective lens is provided on the branched optical path, a plurality of measuring light having passed through the pinhole member in an imaging means having a light receiving element on the object to be measured The reflected light from the specified measurement point is received as it is, and the distance between the objective lens and the object to be measured is displaced by the displacement means, and the measurement passes through any one pinhole of the pinhole member. Among the plurality of light receiving elements of the imaging means for receiving the reflected light from the measurement point on the object to be measured designated by the light, the output from the one light receiving element showing the highest detection output corresponds to the measurement point. From light receiving element Selected as a force to measure minute height.

  The pinhole member is formed by forming a plurality of pinholes in a matrix at predetermined intervals on a transparent substrate. Thereby, measurement light is allowed to pass through a plurality of pinholes formed in a matrix at predetermined intervals on a transparent substrate.

  The pinhole member is a Nippon disc having a plurality of pinholes formed in a spiral shape. Thereby, measurement light is allowed to pass through a plurality of pinholes spirally formed on the Nippon disc.

According to the first aspect of the present invention, the plurality of light receiving elements of the imaging means for receiving the reflected light from the measurement point on the measurement object designated by the measurement light that has passed through any one pinhole of the pinhole member Among them, the output from one light receiving element showing the highest detection output can be selected as the output from the light receiving element corresponding to the measurement point, and the minute height can be measured. Therefore, the measurement light that has passed through the pinhole irradiates the object to be measured, and the reflected light from the designated measurement point can be received as it is without passing through the pinhole by the imaging means, and on the light receiving surface of the imaging means. Further, it is not necessary to provide an imaging optical system for forming the pinhole image behind the pinhole member. In addition, since it is not necessary to provide such an imaging optical system, a measurement light source can be provided close to the pinhole member, and an optical system for uniformly irradiating the pinhole member with measurement light from the measurement light source is provided. There is no need to provide it. Therefore, the optical configuration of the apparatus can be simplified, and the apparatus can be manufactured at low cost.

  Moreover, according to the invention which concerns on Claim 2, the measurement of micro height becomes simple and can reduce the manufacturing cost of an apparatus.

  And according to the invention which concerns on Claim 3, the height measurement in an observation area | region can be performed more precisely.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a front view showing an embodiment of a minute height measuring apparatus according to the present invention. This minute height measuring device measures minute heights of protrusions and the like on the object to be measured, and includes a stage 1, a white light source 2, a pinhole member 3, an objective lens 4, and an imaging lens 5. The imaging unit 6, the illumination light source 7, the laser light source 8, the luminous flux regulating unit 9, and the displacing unit 10.

  The stage 1 is configured to place an object 11 to be measured on the upper surface and move it in the horizontal plane in the X and Y directions. The stage 1 is moved by driving means that combines a motor and gears (not shown). . The Y direction is the depth direction in FIG.

  Above the stage 1, a white light source 2 as a measurement light source is provided close to a pinhole member 3 described later. The white light source 2 irradiates the pinhole member 3 with white light (measurement light) L1, and is a xenon lamp, an ultrahigh pressure mercury lamp, a white laser light source, a white LED, or the like.

  A pinhole member 3 is provided in front of the white light L1 in the radiation direction of the white light source 2. As shown in FIG. 2, the pinhole member 3 is formed by forming a plurality of pinholes 12 in a matrix at predetermined intervals. For example, the pinhole member 3 is an opaque film such as chromium (Cr) formed on a transparent substrate 13. 14 is a pinhole mask in which a plurality of pinholes 12 are formed by etching 14. Note that the arrangement pitch of the pinholes 12 is preferably set to be approximately an integral multiple of the arrangement pitch of the light receiving elements of the imaging means 6 described later. Further, the arrangement pitch of the pinholes 12 is preferably sufficiently wide so that the reflected light from the object to be measured 11 of the light passing through the adjacent pinholes 12 does not interfere on the light receiving surface of the imaging means 6. Each pinhole 12 is preferably aligned so as to have a one-to-one correspondence with each light receiving element of the imaging means 6.

  An objective lens 4 is provided on the optical axis connecting the white light source 2 and the stage 1 so as to face the object to be measured 11 placed on the stage 1. The objective lens 4 collects the white light L1 that has passed through the pinhole 12 of the pinhole member 3 on the object to be measured 11, and is attached to the lens holder 15 that is movable parallel to the surface of the stage 1. It consists of a plurality of types of objective lenses 4a to 4d having different magnifications that are detachably held.

  An imaging lens 5 is provided on the optical path between the white light source 2 and the objective lens 4. The imaging lens 5 is combined with the objective lens 4 to form an image of the pinhole 12 of the pinhole member 3 on the object to be measured 11.

An imaging means 6 is provided on the optical path where the optical path from the imaging lens 5 toward the pinhole member 3 is branched by the beam splitter 16. The image pickup means 6 is provided with a plurality of light receiving elements in a matrix and picks up a two-dimensional image on the object 11 to be measured. When measuring a minute height, the pinhole of the pinhole member 3 is used. 12 functions as detection means for detecting the brightness of the reflected light L2 by directly receiving the reflected light L2 from the object 11 to be measured without passing through the pinhole member , such as a CCD camera or a CMOS camera. It is. In this case, the number of light receiving elements that receive the reflected light L2 from the designated measurement point by irradiating the measured object 11 with the white light L1 that has passed through any one pinhole 12 is not one, but a plurality of groups. The light receiving element. However, when the height measurement, in the image processing section not shown, the output from one of the light receiving element shown the detection output of the highest brightness among the group of the plurality of light receiving elements from the light receiving element corresponding to the measurement point Is selected as the output .

  An illumination light source 7 is provided on the optical path where the optical path from the objective lens 4 toward the imaging lens 5 is branched by the beam splitter 17. The illumination light source 7 irradiates the measurement object 11 with illumination light L3 to enable the imaging means 6 to image the surface of the measurement object 11, and is a halogen lamp or the like.

  A laser light source 8 is provided on an optical path where an optical path from the imaging lens 5 toward the white light source 2 is branched by a beam splitter 18. The laser light source 8 emits a laser beam L4, irradiates the object to be measured 11 to process the object to be measured 11, and is a pulse laser that emits a laser beam L4 having a wavelength of 532 nm or 355 nm, for example. .

  Between the imaging lens 4 and the laser light source 8, a light beam restricting means 9 is provided. This light beam restricting means 9 emits the light beam cross-sectional shape of the laser light L4 irradiated to the object 11 to be controlled by the shape restricting portion 19 to a shape corresponding to the machining shape, for example, sliding in the XY plane. It is configured by combining a plurality of possible members. As shown in FIG. 3, a specific example of the configuration is a pair of first members 20 that slide in the X direction in the XY plane and rotate in the directions of arrows A and B in the plane, and above the pair. And a pair of second members 21 that slide in the Y direction and rotate in the directions of arrows C and D in the XY plane, and are formed by the pair of first members 20 and the second member 21. The enclosed opening is used as the shape restricting portion 19.

  Displacement means for moving the main body of the optical system including the white light source 2, the pinhole member 3, the objective lens 4, the imaging lens 5, the imaging means 6, the illumination light source 7, the laser light source 8, and the light beam restricting means 9 so as to move up and down. 10 is provided. The displacing means 10 moves the optical system main body part within a predetermined movement range from below to above or from above to below at a predetermined speed, so that the distance between the objective lens 4 and the object to be measured 11 is increased. For example, a combination of a motor and a gear is used.

  In the above optical system, the position of the pinhole 12 of the pinhole member 3, the position of the light receiving surface of the imaging means 6, and the position of the shape restricting portion 19 of the light flux restricting means 9 are respectively at the imaging position of the objective lens 4. On the other hand, it has a conjugate relationship. In FIG. 1, reference numeral 22 denotes a motor for moving the lens holder 15 in the X direction, reference numeral 23 denotes a ball screw connected to the motor 22 to rotate and move the lens holder 15 in the X direction, and reference numeral 24 denotes the lens holder 15. A reference numeral 25 denotes a total reflection mirror, and reference numeral 26 denotes a field lens that uniformly illuminates the imaging area of the imaging means 6.

Next, the operation of the minute height measuring apparatus configured as described above and the procedure for removing abnormal protrusions (foreign matter) will be described with reference to FIGS. In the following description, the case where the DUT 11 is a color filter substrate will be described.
First, in step S1, the color filter substrate is placed on the stage 1 of the minute height measuring apparatus. Then, the start switch of the apparatus is turned on, and the illumination light source 7 is turned on. Thereby, the illumination light L3 irradiates the color filter substrate surface via the objective lens 4. At the same time, the imaging means 6 is turned on to image the surface of the color filter substrate. At this time, the white light source 2 and the laser light source 8 remain off. In addition, as the objective lens 4, any one of the low-magnification objective lenses 4a to 4c is selected.

  In step S2, the displacing means 10 is turned ON to move the optical system main body up and down, and the autofocus adjustment is performed so that the color filter substrate pattern image picked up by the image pickup means 6 becomes clear. At this time, the image captured by the imaging unit 6 is displayed on a monitor screen (not shown).

  In step S3, a known pattern matching method is applied to the pattern image of the color filter substrate picked up by the image pickup means 6 to detect pattern defects, for example, foreign matters (abnormal protrusions) attached to the pattern. Here, when the pattern defect is not detected ("NO" determination), the process proceeds to step S4, the stage 1 is moved by a predetermined amount in a predetermined direction, and the next observation area is selected.

  On the other hand, if a pattern defect is detected in step S3 ("YES" determination), the process proceeds to step S5, the stage 1 is moved in the X and Y directions, and the defect (foreign material 27) (see FIG. 5) is the objective. It is positioned at the center of the field of view F of the lens 4.

  In step S6, the motor 22 is driven to move the lens holder 15 in the X direction, and the objective lens 4 is replaced with a high-magnification objective lens 4d. When the optical axis of the objective lens 4d and the optical axis of the optical system main body are shifted, the motor 24 is further driven to move the lens holder 15 in the Y direction, and the optical axes are aligned.

  When the objective lens 4 is replaced with a high-magnification objective lens 4d, the displacement means 10 is turned ON again to move the optical system body up and down, and the color filter substrate pattern image picked up by the image pickup means 6 is clear. The autofocus adjustment is performed so that (see FIG. 5A).

  In step S7, the illumination light source 7 is turned off and the white light source 2 is turned on. Thereby, the white light L1 emitted from the white light source 2 passes through the plurality of pinholes 12 of the pinhole member 3 and is irradiated onto the color filter substrate via the objective lens 4. Then, a plurality of measurement points 28 corresponding to the pinholes 12 are designated on the color filter substrate (see FIG. 5B). Further, the reflected light L <b> 2 from each measurement point 28 returns to the white light source 2 side through the objective lens 4, is reflected by the beam splitter 16, and enters the imaging unit 6 as it is.

  In step S8, height measurement is started. That is, the luminance of the reflected light L2 is detected by the light receiving element of the imaging means 6, and the luminance information is stored in a corresponding area of a storage unit (not shown) for each light receiving element that has received the reflected light. At the same time, the height information of the displacement means 10 at this time is detected by a position sensor provided in the displacement means 10 and stored in the storage unit in association with the luminance information.

  Subsequently, the displacing means 10 is turned ON to move the optical system main body upward, for example, at a predetermined speed. At this time, the reflected light L2 from the color filter substrate of the white light L1 that has passed through the plurality of pinholes 12 is received by the plurality of light receiving elements of the imaging means 6, and the luminance of the reflected light L2 is detected at predetermined time intervals. The At the same time, the height information of the displacement means 10 is acquired in synchronization with the detection of the brightness based on the output of the position sensor of the displacement means 10. The luminance information and the height information are associated with each other and stored in the storage unit for each light receiving element.

  Specifically, every time the luminance information is input at a predetermined time interval, the newly input luminance information is compared with the previous luminance information stored in the storage unit. When the new luminance information exceeds the previous luminance information, the luminance information stored in the storage unit is updated. At the same time, the height information is updated. On the other hand, when the brightness information is not updated a plurality of times set in advance, the stored brightness information is detected as the maximum brightness, and the height information when the brightness information is last updated is measured. Save as point height.

  In the present invention, the reflected light L2 from any one measurement point 28 on the color filter substrate is received by a plurality of light receiving elements of the imaging means 6. However, since each light receiving element outputs luminance information individually, at the time of height measurement, an output from one light receiving element that outputs the highest luminance information among the plurality of light receiving elements is performed in an image processing unit (not shown). The output from the light receiving element corresponding to the measurement point 28 is selected and used for height measurement.

  In step S9, when the height measurement of all the measurement points 28 is completed ("YES" determination), the process proceeds to step S10 and the white light source 2 is turned off. At the same time, the displacement means 10 is driven to adjust the height of the optical system body to a predetermined height. This height depends on the power of the laser beam to be irradiated, and is, for example, the pattern surface of the color filter substrate, the apex of the foreign material 27, or the intermediate height position thereof, and is determined by experiments.

  Then, it moves to the removal stage of the foreign material 27 by laser irradiation. In this case, first, in step S <b> 11, the illumination light source 7 is turned on, and an image of a defect pattern including the foreign material 27 is captured by the imaging unit 6.

  In step S12, the first member 20 and the second member 21 of the light beam restricting means 9 are moved so that the size of the shape restricting portion 19 matches the size of the foreign matter 27. This operation is changed in conjunction with the movement of the first member 20 and the second member 21, for example, and a window 29 corresponding to the shape restricting portion 19 is displayed on the monitor screen. The positions of the first member 20 and the second member 21 are manually adjusted so as to be accommodated (see FIG. 5C). Alternatively, the contour of the foreign material 27 is detected from the contrast of the image captured by the imaging means 6, and the maximum width in the X and Y directions of the foreign material 27 (the width considering the magnification of the objective lens 4) is calculated based on the detected contour. The positions of the first member 20 and the second member 21 are automatically adjusted so that the width in the X and Y directions of the shape restricting portion 19 of the restricting means 9 matches the calculated width in the X and Y directions. May be. The window 29 can be generated by providing the first member 20 and the second member 21 with position sensors and using the outputs of the position sensors.

  In step S <b> 13, the laser light source 8 is turned ON, and the laser light L <b> 4 is irradiated for a predetermined time with a preset power or a power automatically set according to the height of the foreign material 27. Thereby, the foreign material 27 is instantaneously gasified and removed by the heat of the laser beam L4 (see FIG. 5D).

  In step S14, the substrate surface is observed by a monitor, and the removal status of the foreign matter 27 is confirmed. In step S15, the motor 22 is driven and the lens holder 15 is moved to replace the objective lens 4 with one of the low-magnification objective lenses 4a to 4c. Then, the process proceeds to step S4, where the stage 1 is moved to X, Moving in the Y direction, the observation area of the color filter substrate is moved to the next area. In this way, steps S1 to S14 are executed in the next observation region.

  In step S14, after confirming the removal status of the foreign matter 27, the height may be measured again in the same manner as described above. In this case, for example, when the foreign matter 27 cannot be completely removed and a height exceeding the allowable range is detected, the laser light irradiation may be performed again.

  In the above description, the defect correction of the color filter substrate, particularly the removal of the foreign matter 27 has been described. However, the present invention is not limited to this, and the present invention is also applicable to the case where a recess having a predetermined depth is formed in the object to be measured 11. Can be applied. In this case, the processing accuracy can be improved by performing laser processing while measuring the processing amount (processing depth) for the DUT 11.

  In the above embodiment, the case where the distance between the objective lens 4 and the object to be measured 11 is displaced by moving the optical system main body in the vertical direction when performing height measurement has been described. The invention is not limited to this, and the stage 1 may be moved in the vertical direction, or the imaging lens 5 may be displaced in the optical axis direction.

  Further, in the above embodiment, the case where the pinhole member 3, the white light source 2, and the imaging unit 6 are provided on the optical path branched from the imaging lens 5 to the light beam regulating unit 9 by the beam splitter 18 has been described. The present invention is not limited to this, and each of the above-described components may be provided on an optical path branched from the optical path from the objective lens 4 toward the imaging lens 5. Also in this case, the formation position of the pinhole 12 of the pinhole member 3, the position of the light receiving surface of the imaging means 6, and the position of the shape restricting portion 19 of the light flux restricting means 9 are respectively conjugate with the imaging position of the objective lens 4. It is comprised so that it may become a relationship.

  In the above embodiment, the case where the measurement light source is the white light source 2 has been described. However, the present invention is not limited to this, and may be, for example, a laser light source or LED that emits monochromatic light of red, green, and blue. Alternatively, the white light source 2 and the laser light source or the like may be switched using a switch.

  Furthermore, in the above-described embodiment, the case where the light flux restricting means 9 is configured by combining a plurality of members that can slide in the XY plane has been described. However, the present invention is not limited to this, and the light flux restricting means 9 is Alternatively, a micromirror device in which a plurality of individually tiltable micromirrors are arranged in a matrix may be used. Thereby, the light beam cross-sectional shape of a laser beam can be arbitrarily set according to a processing shape.

  Furthermore, in the above embodiment, the case where the pinhole member 3 is formed by forming a plurality of pinholes 12 in a matrix at a predetermined interval on a transparent substrate has been described, but the present invention is not limited to this, The pinhole member 3 may be a Nippon disc having a plurality of pinholes formed in a spiral shape. In this case, the height in the observation region can be measured more precisely by rotating the Nippon disc at a predetermined speed.

  In the above description, the laser processing function has been described. However, the present invention is not limited to this, and the height of the projection is measured and the projection is removed by tape polishing. Can be applied.

It is a front view which shows embodiment of the micro height measuring apparatus by this invention. It is a top view which shows the example of 1 structure of the pinhole member used in the said micro height measurement apparatus. It is a top view which shows the example of 1 structure of the light beam control means used in the said micro height measuring apparatus. It is a flowchart explaining the removal procedure of the abnormal protrusion (foreign material) by the said micro height measurement apparatus. It is explanatory drawing shown about the removal procedure of the abnormal protrusion (foreign material) by the said micro height measurement apparatus.

Explanation of symbols

2 ... White light source (light source for measurement)
DESCRIPTION OF SYMBOLS 3 ... Pinhole member 4 ... Objective lens 5 ... Imaging lens 6 ... Imaging means 8 ... Laser light source 9 ... Light beam control means 10 ... Displacement means 11 ... Object to be measured 19 ... Shape control part L1 ... White light (measurement light)
L2 ... Reflected light L4 ... Laser light

Claims (3)

A measurement light source for irradiating measurement light to a pinhole member formed with a plurality of pinholes;
An objective lens that is provided opposite to the object to be measured and collects the measurement light that has passed through the pinhole on the object to be measured;
The optical path extending from the objective lens to the pinhole member is provided on the branched optical path, the measurement point the measurement light passing through the pinhole comprises a plurality of light receiving elements specified by irradiating onto the object to be measured Imaging means for receiving reflected light from the light as it is,
Displacement means for displacing a distance between the objective lens and the object to be measured;
Equipped with a,
The highest detection output among the plurality of light receiving elements of the imaging means that receives the reflected light from the measurement point on the measurement object designated by the measurement light that has passed through any one pinhole of the pinhole member A minute height measuring apparatus , wherein the output from one light receiving element indicating the above is selected as the output from the light receiving element corresponding to the measurement point .   2. The minute height measuring device according to claim 1, wherein the pinhole member is formed by forming a plurality of pinholes in a matrix at predetermined intervals on a transparent substrate.   2. The minute height measuring device according to claim 1, wherein the pinhole member is a nippo disk in which a plurality of pinholes are spirally formed.

Images