JP2018105853A - Gap measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gap measurement method capable of measuring a gap between a mask plate and a substrate.SOLUTION: The gap measurement method includes: a step for making two directions orthogonal to each other in one surface of a substrate Sw an X-axis direction and a Y-axis direction and separately arranging a measurement part 11 having light projection elements 6 and light receiving elements 7 under a measurement object; a step for acquiring scanned data corresponding to a displacement amount of a mask plate Mp with respect to the measurement part 11 by determining a position at which light from the light projection elements 6 is reflected at the lower surface of the substrate Sw as a start position, causing the measurement part 11 to relatively scan the measurement object from the start position at least in one direction of the X-axis direction and the Y-axis direction, irradiating a measurement position at which the light from the light projection elements 6 is reflected at the mask plate Mp with light from the light projection elements 6 and receiving the reflection light with the light receiving elements 7; and a step for measuring a gap Gp between the substrate Sw and the mask plate Mp from the scanned data and the plate thickness of the mask plate Mp.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a gap measurement method, and more specifically, includes a mask plate that has a through-hole penetrating in the thickness direction on one surface of a substrate to closely arrange (adhere) a mask plate that defines a processing range to the substrate. ) For measuring the gap between the substrate and the mask plate.

  For example, a vacuum deposition method is known as one of methods for manufacturing an organic EL device. In this vacuum deposition method, a vacuum chamber capable of forming a vacuum atmosphere is provided with a substrate such as a glass substrate and a through-hole (having an opening diameter of, for example, 20 to 50 μm) penetrating in the thickness direction (processed). ) A mask plate that defines the range is placed on top of each other, and the vapor deposition material is sublimated or vaporized from the vapor deposition source, and this sublimated or vaporized vapor deposition material passes through the mask plate on one side of the substrate (ie, the film formation surface). Various thin films are formed in a predetermined pattern by adhering and depositing on (see, for example, Patent Document 1). In this case, in consideration of the product yield, it is usual to form a film by a so-called deposition method by disposing an evaporation source below the mask plate. At this time, in order to form a film with a predetermined pattern while suppressing so-called mask blur as much as possible, at the time of film formation by vacuum vapor deposition, a mask plate is disposed close to one surface of the substrate, more preferably, the substrate and the mask plate Are preferably adhered over the entire surface.

  For this reason, the substrate and the mask plate are aligned and stacked in the vertical direction with the direction from the mask plate to the substrate facing upward, and the holding means is disposed on the substrate via the touch plate so as to sandwich the substrate. It is generally known that the mask plate is held on the touch plate. As the holding means, a magnet array in which a plurality of magnets are arranged in line is used. Here, in recent years, the substrate to be processed has been increased in size, and accordingly, the mask plate itself is also increased in size (for example, 1500 mm × 1800 mm), and is formed on the substrate through each through hole of the mask plate. In order to form a film with high accuracy so that the film has a substantially rectangular outline, a foil plate having a thickness of several tens to several hundreds of μm is used as the mask plate. In this case, even if the mask plate is held by the touch plate so that the substrate is sandwiched by the holding means, the mask plate and the substrate are caused by, for example, the bending due to the weight of the mask plate or the difference in the magnetic field strength of the magnet array in the mask plate surface. There may be a local gap between In this case, depending on the gap between the mask plate and the substrate, mask blur occurs and the product yield is reduced.

  Therefore, conventionally, the substrate is held by the holding means and the mask plate is held by the touch plate, and the film is transferred to the vacuum chamber and formed into a film. The position where has occurred was specified. However, such a method requires a great amount of time and cost to identify the gap. Therefore, it has been desired to develop a method for measuring the gap between the mask plate and the substrate without evaluating the substrate after film formation.

JP 2013-93278 A

  In view of the above points, the present invention provides a gap measuring method capable of measuring a gap between a mask plate and a substrate after the mask plate is held on the touch plate so as to sandwich the substrate with holding means. The task is to do.

  In order to solve the above problem, when a mask plate that has a through-hole penetrating in the thickness direction on one surface of the substrate and defines a processing range to the substrate is disposed close to the substrate, the space between the substrate and the mask plate The gap measuring method of the present invention for measuring the gap of the substrate is arranged by aligning the substrate and the mask plate in the vertical direction with the direction from the mask plate to the substrate facing up, and holding the substrate on the substrate via the touch plate A step of preparing a measurement object in which a mask plate is held on a touch plate so as to sandwich the substrate by arranging means, and two directions orthogonal to each other in one surface of the substrate are defined as an X-axis direction and a Y-axis. A measurement unit having a light projecting element and a light receiving element, and a position where light from the light projecting element is reflected from the lower surface of the substrate as a starting position. From the starting position, the measurement unit is scanned relative to the measurement object in at least one direction of the X axis direction and the Y axis direction, and the light from the light projecting element is reflected from the mask plate at the measurement position. The substrate and the mask are obtained from the step of acquiring the scanning data corresponding to the displacement amount of the mask plate with respect to the measurement unit by irradiating the light and receiving the reflected light by the light receiving element, and the thickness of the scanning data and the mask plate. The method includes measuring a gap between the plate and the plate.

  According to the present invention, the light from the light projecting element is irradiated to a predetermined position on the lower surface of the substrate at the starting position, and the reflected light from the lower surface is received by the light receiving element, which is used as a reference. Next, for example, when the spot diameter of light emitted from the light projecting element is set as a scanning pitch, the measurement unit is relatively intermittently scanned from the starting position at this scanning pitch, and light is emitted from the light projecting element. A rectangular wave shape corresponding to the amount of displacement of the mask plate with respect to the measurement unit, which is reflected on the mask plate bottom surface, one reflected on the inner surface of the through hole of the mask plate, and one reflected again on the bottom surface of the substrate is sequentially received by the light receiving element. Can be obtained. For example, when the mask plate is bent, the gap between the substrate and the mask plate is determined from the peak value at each measurement position reflected on the lower surface of the mask plate and the plate thickness of the mask plate. It can be measured. As described above, in the present invention, the gap between the substrate and the mask plate can be efficiently measured within the substrate surface without evaluating the substrate after film formation. The gap measurement method of the present invention can be performed not only in the air but also in a vacuum atmosphere. For example, in order to transport a substrate under atmospheric pressure into the vacuum chamber, the gap measurement method is connected to the vacuum chamber via a gate valve. It is possible to carry out the film formation as it is by transporting the measured material in a vacuum atmosphere. In the present invention, “proximity arrangement” is a concept including the case where the substrate and the mask plate are in close contact over the entire surface.

  By the way, among the through holes provided in the mask plate, for example, each through hole of the mask plate has an inner surface that extends downwardly for the purpose of improving the film formation rate. When such a through hole is formed in the mask plate by etching or the like, the end-spreading inner surface of each through hole may be distorted, resulting in a measurement error between the substrate and the mask plate. Apparent gaps can occur. Therefore, in the present invention, the measurement position can include a light receiving light reflected from the inner edge of the bottom surface of the through hole (that is, a light reflected from the edge of the through hole). As a result, if the peak value at the measurement position matches the mask plate and the plate thickness, it can be determined that there is no gap between the substrate and the mask plate, and the peak value of the rectangular wave and the plate thickness of the mask plate can be determined. This difference can be measured as a gap between the substrate and the mask plate. In this case, in order to perform more accurate measurement, it is preferable to irradiate light perpendicularly to the substrate from the light projecting element. Therefore, the position where the light from the light projecting element is reflected by the lower surface of the substrate is set as the starting position. The measurement unit is scanned relative to the measurement object in at least one of the X-axis direction and the Y-axis direction from the starting position, and the light-receiving element at a plurality of positions where the light from the light projecting element is reflected by the lower surface of the substrate. The step of receiving the reflected light and measuring the tilt of the substrate with respect to the XY plane and tilting the measuring unit according to the measured tilt of the substrate so that the light from the light projecting element is incident at a right angle to the substrate. You may employ | adopt the structure which further includes a process. In the present invention, it is preferable that the measurement unit measures the displacement amount by spectral interference using a broadband laser.

  By the way, as described above, the measurement object is irradiated with laser light having a spot diameter smaller than the diameter of the through-hole, for example, and the spot diameter is set as the scanning pitch. When measuring the displacement of the mask plate relative to the measurement part by scanning relatively across the hole, the viewing angle is very small, so check which position on the mask plate is actually measured. There is a possibility that a gap generated between the mask plate and the substrate that causes mask blur cannot be specified. Therefore, in the present invention, it is preferable that the method further includes a step of enlarging and displaying a region irradiated with light from the light projecting element of the measurement unit to the measurement object.

(A) is a schematic cross section which shows the measuring apparatus which enforces the gap measuring method of embodiment of this invention, (b) is a schematic cross section which follows the Ib-Ib line | wire of Fig.1 (a). The schematic cross section which shows a measurement object. (A) And (b) is a figure explaining the gap measuring method of embodiment of this invention. The figure which shows typically the modification of the measuring device shown in FIG.

  Hereinafter, with reference to the drawings, the substrate is a rectangular glass substrate (hereinafter simply referred to as “substrate Sw”), and one surface of the substrate Sw is provided with a through-hole Mf penetrating in the plate thickness direction to process the substrate Sw. An embodiment of the gap measuring method of the present invention for measuring the gap Gp between the substrate Sw and the mask plate Mp when the mask plate Mp defining the range is brought into close contact will be described. In the following, the direction from the mask plate Mp toward the substrate Sw is defined as the Z-axis direction, and two directions orthogonal to each other within one surface of the substrate orthogonal to the Z-axis direction are defined as the X-axis direction and the Y-axis direction.

  Referring to FIG. 1, LC is a spare chamber connected to a vacuum chamber (not shown) through a gate valve (not shown) in which a film can be formed on the substrate Sw by a vacuum deposition method. A vacuum pump 10 is connected to the preliminary chamber LC so that the inside thereof can be evacuated from atmospheric pressure to a predetermined pressure. The preliminary chamber LC is provided with a measuring device 1 that performs the gap measuring method of the present embodiment. The measuring device 1 includes a measuring unit 11 and a moving unit 12 that can move the measuring unit 11 in at least one of the X-axis direction and the Y-axis direction. The moving unit 12 includes a gate-shaped frame 3 having a slider (not shown) slidably engaged with two rails 2 and 2 laid on the bottom surface of the spare chamber LC along the X-axis direction. The frame 3 can be moved back and forth in the X-axis direction at a predetermined pitch by a motor (not shown). The frame 3 is provided with a feed screw 4 extending in the Y-axis direction. A mounting portion (not shown) of the support base 5 is screwed to the feed screw 4, and the support base 5 is fixed at a predetermined pitch by a motor (not shown). It can be moved forward and backward in the Y-axis direction. A measuring unit 11 is provided on the support 5.

  The measurement unit 11 includes a displacement sensor having a light projecting element 6 and a light receiving element 7. In this case, a semiconductor laser, a fiber head, or the like can be used as the light projecting element 6, a CMOS or CCD can be used as the light receiving element 7, and the measurement method is based on reflected light. In addition, it is possible to use what measures by the principle of triangulation and what measures by the phase difference between the projected laser and its reflected light. Further, in order to efficiently measure the gap Gp on the order of μm, it is preferable that the displacement amount can be measured by the spectral interference method using a broadband laser. In addition, since the measurement part 11 itself is a well-known thing, the detailed description beyond this is abbreviate | omitted. Although not specifically illustrated and described, the measuring device 1 includes a controller that performs overall control of the operation of the measuring unit 11 and the moving unit 12 and measurement processing, and the controller acquires, for example, scan data described later, The gap Gp between Sw and the mask plate Mp is measured.

  A support frame 8 is provided in the upper space of the preliminary chamber LC separated from the measurement unit 11, and the measurement object Mo is supported by the support frame 8 in a posture with a mask plate Mp described below on the lower side. Referring to FIG. 2, the measurement object Mo is composed of a mask plate Mp, a substrate Sw, a touch plate Tp, and a magnet array Ma serving as a holding unit. The mask plate Mp is selected from a metal material having a small coefficient of thermal expansion near normal temperature, and is made of, for example, Invar. In the mask plate Mp, a plurality of through holes Mf penetrating in the thickness direction are opened in a predetermined pattern. In this case, as the mask plate Mp, a film that is formed on the substrate Sw through the through hole Mf has a substantially rectangular outline, and in order to form such a film with high accuracy, several A foil-like one having a thickness of 10 μm to several hundred μm is used, and is held by a support frame 8 having a thickness greater than that of the mask plate Mp. Further, the inner surface of the through hole Mf is formed in a mortar shape that spreads downward toward the bottom for the purpose of improving the film formation rate (see FIG. 3). In this case, the outline of the through hole Mf on the upper surface of the mask plate Mp is appropriately set according to the pattern to be formed, such as a circle or an ellipse. Note that when such a through hole Mf is opened, the inner surface of each through hole Mf may be distorted, resulting in a distortion between the substrate Sw and the mask plate Mp. Apparent gaps can occur.

  The touch plate Tp is selected from a metal material having a low magnetic permeability, and for example, austenitic stainless steel is used. In this case, the lower surface of the touch plate Tp with which the substrate Sw is in close contact is processed to have a predetermined flatness, and when the substrate Sw is in close contact with the entire surface of the touch plate Tp, the substrate Sw is held flat. To fulfill. The magnet array Ma has a plate-like yoke Yo and a bar magnet Bm having the same shape and the same kind of longitudinally long Y-axis on the lower surface of the yoke Yo, with the lower magnetic poles alternately spaced in the X-axis direction. They are arranged in line. Below, the gap measuring method of this embodiment is demonstrated concretely.

  First, the measurement object Mo is prepared in the preliminary chamber LC. A mask plate Mp is installed on the support frame 8 provided in the preliminary chamber LC. Next, the substrate Sw is superimposed on the mask plate Mp. In this case, an alignment mark (not shown) is provided at a predetermined position between the mask plate Mp and the substrate Sw, and the position of the substrate Sw with respect to the mask plate Mp is adjusted while imaging the alignment mark with a CCD camera or the like. Then, after the touch plate Tp is placed on the substrate Sw by being lowered from above, the magnet array Ma is placed on the touch plate Tp by being lowered from above. Thereby, the mask plate Mp is held in close contact with the touch plate Tp so as to sandwich the substrate Sw, and the measurement object Mo is prepared.

  Next, when the measurement object Mo is prepared, a position where the light from the light projecting element 6 is reflected by the substrate lower surface Sw1 is set as a starting position (a position where the measurement unit 11 is at the leftmost end in FIG. 3A). At this starting position, light is projected from the light projecting element 6 to a predetermined position on the substrate lower surface Sw1 (a position where the light passes through the through hole Mf of the mask plate Mp), and the reflected light from the substrate lower surface Sw1 is irradiated. Light is received by the light receiving element 7, and this is used as a reference. Then, the measuring unit 11 is relatively scanned by the moving unit 12 from the starting position in at least one of the X-axis direction and the Y-axis direction. Here, for example, the spot diameter of the light emitted from the light projecting element 6 is set as a scanning pitch, and the measuring unit 11 is relatively intermittently scanned from the starting position to the right side in FIG. 3A at this scanning pitch. When the light is emitted from the light projecting element 6, the light reflected by the inner surface of the through hole Mf of the mask plate Mp and the light reflected by the lower inner edge portion Mp2 of the through hole Mf (that is, in FIG. 3A) The light reflected at the left edge of the through hole Mf), the light reflected by the mask plate lower surface Mp1, and the light reflected by the other lower surface inner edge Mp2 of the through hole Mf (that is, the through hole Mf in FIG. 3A). The light reflected at the other lower surface inner edge Mp2 of the through hole Mf (that is, the reflected light at the right edge) is sequentially received by the light receiving element 7 for one cycle. This operation is repeated (see FIG. 3A). Thereby, the rectangular wave-shaped scanning data (refer FIG.3 (b)) according to the displacement amount of the mask plate Mp with respect to the measurement part 11 is acquirable. When the mask plate Mp is bent, for example, the peak value at each measurement position reflected by the mask plate lower surface Mp1 and the thickness of the mask plate Mp are used to determine the distance between the substrate Sw and the mask plate Mp. The gap Gp can be measured. After the measurement, when all the gaps Gp between the substrate Sw and the mask plate Mp are in a predetermined range, the measurement object Mo is transferred from the preliminary chamber LC to a vacuum chamber (not shown), and a predetermined deposition process is performed. Done.

  As described above, in this embodiment, the gap Gp between the substrate Sw and the mask plate Mp can be efficiently measured in the surface of the substrate Sw without evaluating the substrate Sw after film formation. In this case, since the configuration in which the measurement unit 11 is arranged separately below the measurement object Mo is employed, there is no problem that the measurement unit 11 comes into contact with the mask plate Mp and scratches when measuring the gap Gp.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. In the above-described embodiment, the example using the magnet array Ma as the holding unit has been described as an example. However, as long as the mask plate Mp can be held on the touch plate Tp so as to sandwich the substrate Sw, the form is not limited. Moreover, in the said embodiment, although the thing provided with the flame | frame 3 and the feed screw 4 was demonstrated to the example as the moving part 12 of the measuring device 1, it is not limited to this, The measuring part 11 is from the measurement object Mo. Any form may be used as long as it can move in the X-axis direction and the Y-axis direction while maintaining a constant interval in the Z-axis direction. On the other hand, the measurement unit 11 may be fixed, and the measurement object Mo may be configured to be movable in the X-axis direction and the Y-axis direction.

  In the above embodiment, the position of the measurement unit 11 in the Z-axis direction cannot be changed. However, when the measurement unit 11 is configured to be movable up and down in the Z-axis direction and the measurement object Mo is installed at a predetermined position, It may be configured to be retracted to a position away from the measuring object Mo and to be close to the measurement object Mo during gap measurement. Furthermore, an angle adjusting mechanism is attached to the light emitting element 6 and the light receiving element 7 so that the incident angle of light with respect to the mask plate Mp and the reflection angle at the mask plate Mp can be adjusted. Since a well-known thing can be used as the raising / lowering mechanism and angle adjustment mechanism of the measurement part 11, detailed description is abbreviate | omitted here.

  By the way, when the through-holes Mf having inner surfaces that are diverging downward as shown in FIGS. 2 and 3A are formed in the mask plate Mp by etching or the like, the divergent inner surfaces of the respective through-holes Mf are distorted. As a result, an apparent gap due to a measurement error may occur between the substrate Sw and the mask plate Mp. In such a case, if the light reflected by the lower surface inner edge portion Mp2 of the through hole Mf is included as the measurement position, the substrate Sw can be obtained if the peak value at the measurement position matches the plate thickness of the mask plate Mp. If there is a difference between the peak value of the rectangular wave and the plate thickness of the mask plate Mp, this difference is calculated between the substrate Sw and the mask plate Mp. It can be measured as the gap Gp.

  Further, in the case where the measurement position includes light reflected by the lower surface inner edge portion Mp2 of the through hole Mf, it is necessary to irradiate light perpendicularly to the substrate Sw from the light projecting element 6 in order to accurately measure. Therefore, a position where the light from the light projecting element 6 is reflected by the substrate lower surface Sw1 is set as a starting position, and the measuring unit 11 is relative to the measurement object Mo in at least one direction of the X axis direction and the Y axis direction from the starting position. Scanning is performed, and the reflected light is received by the light receiving element 7 at a plurality of positions (at least three points) where the light from the light projecting element 6 is reflected by the substrate lower surface Sw1, and the inclination of the substrate Sw with respect to the XY plane is measured. . Then, according to the measured tilt of the substrate Sw, if the measuring unit 11 is tilted using a known tilt mechanism or the like, the light from the light projecting element 6 can be incident on the substrate Sw at a right angle. It is advantageous. It should be noted that an articulated robot having five or more axes can be used for moving the measuring unit 11.

  In addition, when using what has high resolution as the measurement part 11, it is necessary to shorten the distance of the measurement part 11 and the mask plate Mp. For this reason, when there is much deflection amount of the mask plate Mp, if the measurement part 11 is moved, there exists a possibility that the measurement part 11 may contact the mask plate Mp. Therefore, in addition to the measurement unit 11, another measurement unit having a low resolution that can increase the distance between the measurement unit 11 and the mask plate Mp is further provided, and the tilt and the deflection of the substrate Sw are made the same as the above by the other measurement unit. The measurement may be performed, and it may be scanned after confirming that it does not contact the mask plate Mp even if the measurement unit 11 is moved.

  By the way, as described above, the measuring object Mo is irradiated with laser light having a spot diameter smaller than the diameter of the through hole Mf, for example, by the light projecting element 6 and the spot diameter is set as the scanning pitch. Is scanned relative to the mask plate Mp so as to cross the through-hole Mf (see FIG. 3A), and the displacement of the mask plate relative to the measurement unit is measured, the viewing angle is very high. Therefore, there is a possibility that it is not possible to confirm which part of the mask plate Mp is actually measured (for example, whether the light from the light projecting element 6 is accurately irradiated to the starting position where measurement is to be started). I cannot judge).

  Therefore, in the measuring apparatus 1 according to the modification of the above embodiment, the imaging unit 20 including, for example, a CCD camera or a microscope is provided on the support base 5 on which the light projecting element 6 and the light receiving element 7 of the measuring unit 11 are installed. Furthermore, it is provided. Then, when light is emitted from the light projecting element 6 to the measuring object Mo by the image pickup means 20, a predetermined area including the light irradiation position is picked up, and this is subjected to image processing to display means such as a display (not shown). ) Can be enlarged and displayed. In this case, after the light projecting element 6 irradiates the measurement object Mo and before the relative scanning of the measurement unit 11 with respect to the mask plate Mp, the imaging unit 20 includes a predetermined position including the light irradiation position. A step of imaging the region is further provided, for example, confirmation of a starting position where measurement is to be started is performed. Thereby, it is possible to surely grasp which part of the mask plate Mp is actually measured, and it is possible to reliably identify the gap Gp generated between the mask plate Mp and the substrate Sw causing the mask blur.

Gp ... Gap, Sw ... Substrate, Mf ... Through hole, Mp ... Mask plate, Tp ... Touch plate, Ma ... Magnet array, holding means, Mo ... Measurement object, 11 ... Measurement unit, 6 ... Light projecting element, 7 ... Light receiving element, Bm ... magnet.

Claims (5)

A gap for measuring the gap between the substrate and the mask plate when a mask plate that has a through-hole penetrating in the thickness direction on one side of the substrate and that defines the processing range for the substrate is placed close to the substrate. Measuring method,
With the direction from the mask plate to the substrate facing up, the substrate and the mask plate are aligned and stacked in the vertical direction, and the holding means is arranged on the substrate via the touch plate so as to sandwich the substrate. Preparing a measurement object with a mask plate held on,
A step in which two directions orthogonal to each other in one surface of the substrate are set as an X-axis direction and a Y-axis direction, and a measuring unit having a light projecting element and a light receiving element is separately arranged below the measurement object;
The position where the light from the light projecting element is reflected from the lower surface of the substrate is set as a starting position, and the measuring unit is scanned relative to the measurement object in at least one of the X-axis direction and the Y-axis direction from this starting position. By irradiating light from the light projecting element at the measurement position where the light from the optical element is reflected by the mask plate and receiving the reflected light by the light receiving element, scanning data corresponding to the amount of displacement of the mask plate relative to the measurement unit is obtained. A process of acquiring;
A gap measuring method comprising a step of measuring a gap between a substrate and a mask plate from scanning data and a plate thickness of the mask plate. The gap measuring method according to claim 1, wherein each through hole of the mask plate has an inner surface that is diverging downward.
The gap measurement method characterized by including what receives the light reflected in the lower surface inner edge part of a through-hole in the said measurement position. The gap measuring method according to claim 2, wherein the light is irradiated from the light projecting element perpendicularly to the substrate.
The position where the light from the light projecting element is reflected from the lower surface of the substrate is set as a starting position, and the measuring unit is scanned relative to the measurement object in at least one of the X-axis direction and the Y-axis direction from this starting position. The light receiving element receives the reflected light at a plurality of positions where the light from the optical element reflects on the lower surface of the substrate, measures the inclination of the substrate with respect to the XY plane, and the light from the light projecting element is perpendicular to the substrate. And a step of tilting the measurement unit according to the measured tilt of the substrate so as to be incident on the gap.   The gap measurement method according to claim 1, wherein the measurement unit measures the displacement by spectral interference using a broadband laser. The gap according to any one of claims 1 to 4, further comprising a step of enlarging and displaying a region irradiated with light from the light projecting element of the measurement unit to the measurement object. Measurement method.

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