JP4639034B2 - Focus adjustment method and focus adjustment apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a focus adjustment method and a focus adjustment apparatus necessary for accurately aligning a pair of aligned objects, and more particularly, to manufacture flat panel displays such as organic EL (electroluminescence) displays and liquid crystal displays. The present invention relates to a focus adjustment method and apparatus performed at the time of alignment of a glass substrate required in the above.
[0002]
[Prior art]
In the organic EL display manufacturing apparatus, in a film forming apparatus for forming and patterning an organic EL material on a glass substrate, a metal mask 5 provided with openings 8 having a desired pattern is formed on the glass substrate 4 as shown in FIG. A pattern is placed on the glass substrate 4 that is disposed underneath and evaporates the material from below to match the opening. Therefore, it is necessary to align the glass substrate 4 and the metal mask 5 with high accuracy prior to the vapor deposition process.
[0003]
As an alignment method, alignment marks 6 and 7 are provided on the glass substrate 4 and the metal mask 5, respectively, and the image is taken by the imaging device 1 including the CCD camera 2 from above, and the amount of displacement of the alignment marks 6 and 7 is determined. Glass so that the centers of these marks 6 and 7 coincide with each other, that is, the deviation amount of the alignment marks 6 and 7 obtained by photographing is within a predetermined range set in advance. The substrate 4 is moved.
[0004]
As shown in FIG. 5, the alignment marks 6 and 7 are formed of a reflective film such as chromium on the glass substrate 4 and a dedicated opening provided separately from the one for vapor deposition on the metal mask 5. It is common. It is desirable to make the alignment mark 6 on the glass substrate 4 as small as possible so as not to hide the alignment mark 7 on the metal mask 5.
[0005]
When the metal mask 5 is aligned with the glass substrate 4, it is necessary to keep the glass substrate 4 and the metal mask 5 spaced apart from each other up and down, but the glass substrate 4 is enlarged and the amount of bending is somewhat large. In this case, the above-described interval must be increased, and in some cases, the depth of field of the imaging device 1 may be exceeded. In order to adapt to such a situation, an elevating mechanism 13 capable of raising and lowering the imaging apparatus 1 is provided, and an operation for focusing on the alignment marks 6 and 7 is required every time the glass substrate 4 and the metal mask 5 are imaged. Met.
[0006]
As described above, as a focus adjustment method in the alignment step, there is conventionally a method based on the differential component of the video signal from the CCD camera. The integrated value of the differential signal of the image is used as an index of image sharpness (hereinafter abbreviated as a sharpness value), and the position where the sharpness value is maximized is detected while moving the focus position. For example, the one disclosed in Patent Document 1 is known.
[0007]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 8-21281
[Problems to be solved by the invention]
FIG. 6 shows a graph in which sharpness values are plotted with the horizontal axis representing the focal length by the vertical movement of the imaging apparatus 1 using the lifting mechanism 13 in the focus adjustment method according to the conventional technique. As can be seen from this graph, the sharpness value at the in-focus position of the metal mask 5 is relatively large and easy to detect, whereas the alignment mark 6 to be imaged is small at the in-focus position of the glass substrate 4. In many cases, the maximum value of the sharpness value becomes small, so that it cannot be detected or erroneous detection occurs.
[0009]
An object of the present invention is to provide a focus adjustment method and a focus adjustment apparatus that can clearly detect both in-focus positions of a pair of aligned objects such as a glass substrate and a metal mask as described above. .
[0010]
[Means for Solving the Problems]
According to the method of the present invention, a first alignment mark is set on one or both of a pair of aligned objects that are arranged to face each other at a predetermined interval, and the other is paired with the first alignment mark. Both alignment bodies are set so that the second alignment mark is set and the amount of deviation from the normal position of both marks in the image including both alignment marks imaged by the imaging means is within a preset range. Prior to the alignment for adjusting the relative position of each of the alignment objects, a focus adjustment method for focusing each of the pair of alignment objects is provided with an auxiliary mark on one of the alignment objects in close proximity to the alignment mark. The imaging means is operated while adjusting the distance between the imaging means and the to-be-aligned body, and the focal position is when the differential component of the video signal by the imaging means takes a maximum value.
[0011]
According to the method of the present invention , since the auxiliary mark is provided in the vicinity of at least one of the pair of alignment marks, the differential component of the video signal is increased by adding the image of the auxiliary mark. Accordingly, even if only the first alignment mark or only the second alignment mark has a small size, the sharpness value obtained by imaging cannot be detected small, or erroneous detection has occurred. The ingredients are increased so that sufficient sharpness values are obtained.
[0012]
As a result, even when the alignment mark of the alignment target is small, erroneous detection of the focal position is reduced, and the focus adjustment can be performed reliably and easily, and a focus adjustment method with excellent reliability can be provided. It was.
[0013]
The method of the present invention, when the previous SL auxiliary mark is placed only on one of the alignment body, and an auxiliary mark, so as not to be captured which overlap the alignment indicia of the alignment member is not set Further, the auxiliary mark and the alignment mark are misaligned.
[0014]
According to the method of the present invention , an image taken by the imaging means can be obtained in a state where the auxiliary mark and the alignment mark of the alignment object to which the alignment mark is not set do not overlap, so that “the differential component of the video signal increases. And a sufficient sharpness value can be obtained ”.
[0015]
The method of the invention, while the glass substrate of the alignment of a pair, and, together with the other is metal mask, a reflective film for the first alignment mark provided on the surface of the glass substrate, and, The second alignment mark is a through hole formed in the metal mask in a state larger than the reflective film.
[0016]
According to the method of the present invention , it is suitable for a focus adjustment method performed at the time of alignment of a glass substrate that is necessary in the manufacture of a panel display. The product can be used, and the metal mask alignment mark can be made inexpensively by making holes.
[0017]
The configuration of the present invention includes a first alignment mark set on one alignment body of a pair of alignment bodies opposed to each other at a predetermined interval in the focus adjustment device, and the first alignment mark An imaging means capable of imaging an auxiliary mark provided in the vicinity and a second alignment mark set on the other aligned body, and differentiation of an image signal of a portion including the alignment mark imaged by the imaging means Means for extracting a component and means for detecting a focal position at which the differential component of the imaging signal takes a maximum value are provided.
[0018]
The configuration of the present invention is an apparatus of the method of the present invention , and can obtain the same effects as the effects of the method of the present invention .
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the alignment apparatus I includes a glass substrate 4, a metal mask 5, and a vapor deposition source 11 that are supported by a substrate moving mechanism 9 so as to be movable in the vertical and horizontal directions. A plurality of imaging devices (an example of imaging means) 1 are mounted on the vacuum vessel 10 so that the vertical position can be adjusted via the lifting mechanism 13 and the image processing device (the differential component in the present invention is extracted). An example of both the means t for performing the operation and the means k for detecting the focal position) 14 and the actuator control device 15 are provided.
[0020]
The two image pickup devices 1 are configured to include a CCD camera 2, a lens 3, and the like, and are supported by an elevating mechanism 13 so as to be vertically movable and locked. Reference numeral 12 denotes a window for photographing the inside of the vacuum vessel 10 with the CCD camera 2, that is, photographing an alignment mark and focusing necessary for an alignment step (described later). In FIG. 1, the support structure of the metal mask 5 is omitted. Note that the number of the imaging devices 1 is not limited to two and may be any number.
[0021]
The glass substrate 4 is attached to the movement output unit 9a of the substrate moving mechanism 9, and a circular substrate alignment mark (first alignment) is used for alignment with the metal mask 5 on each of the left and right ends of the lower surface thereof. An example of the mark) 6 is attached. The metal mask 5 is formed with a plurality of vapor deposition openings 8 and a mask alignment mark (an example of a second alignment mark) 7 that forms a pair with the substrate alignment mark 6 described above. The vapor deposition opening 8 and the mask alignment mark 7 are both formed as through holes, and the mask alignment mark 7 is a circular hole having a diameter several times (3 to 6 times) that of the substrate alignment mark 6.
[0022]
Further, the glass substrate 4 is provided with an auxiliary alignment mark 16 (which is an example of an auxiliary mark, hereinafter abbreviated as an auxiliary mark) 16 surrounding the substrate alignment mark 6. That is, the same chrome and small width as the substrate alignment mark 6 is formed in a state where the shape in plan view is a slightly horizontally long rectangle, that is, like a cross-sectional shape of a square pipe.
[0023]
The image processing device 14 to which each imaging device 1 is electrically connected and the actuator control device 15 to which the substrate moving mechanism 9 is electrically connected are electrically connected to constitute the alignment control device B. . This alignment control device B is configured to exhibit a focus position detection function and an alignment function.
[0024]
Next, the operation of the alignment apparatus I will be described. The alignment method of the glass substrate 4 and the metal mask 5 by this alignment apparatus I is performed including a focus adjustment process and an alignment process. First, a preparatory process for visually aligning the metal mask 5 with respect to the glass substrate 4 is performed so that the left and right substrate alignment marks 6 are positioned at the centers of the corresponding mask alignment marks 7.
[0025]
Then, the image pickup apparatus 1 is moved up from the lowest position by the lifting mechanism 13 with the CCD camera 2 operated (or moved down from the highest position), and each of the alignment marks 6 and 7 and the auxiliary mark 16 is included. The video signal is processed by the image processing device 14 (see FIG. 1), and the sharpness value based on the differential component is calculated. That is, the elevating mechanism 13 is driven to calculate the sharpness value while changing the focus adjustment of the image pickup apparatus 1, and the position where the maximum value is detected is detected to perform the focus adjustment. This is to detect the relationship between the sharpness value with respect to the focal position (see FIG. 3) and calculate the focal position of the glass substrate 4 and the metal mask 5 from the point where the sharpness value is maximized. It is.
[0026]
FIG. 3 shows the relationship between the sharpness value and the focal position when the substrate auxiliary mark 16 is added. By adding the image of the auxiliary mark 16 to the image of the substrate alignment mark 6, the maximum value of the sharpness value at the in-focus position of the glass substrate 4 becomes larger, so that the focus position can be detected without error.
[0027]
When the focal position is determined, the alignment control device B performs imaging by the imaging device 1, and the alignment marks 6 and 7 are determined in advance from the obtained images (or within the position range of the predetermined region). A positioning step is performed in which the glass substrate 4 is moved back and forth and left and right so as to match the target position. That is, the image (video) output of the imaging device 1 is sent to the image processing device 14 and analyzed, and the automatic position where the substrate moving mechanism 9 is driven based on the command issued from the actuator control device 15 based on the analysis result. Matching control is performed.
[0028]
Here, the relationship between the substrate alignment mark 6 and the auxiliary mark 16 will be described. It is assumed that the pattern of the auxiliary mark 16 does not overlap the mask alignment mark 7 in the field of view of the imaging device 1. That is, as shown in FIG. 2, when the mask alignment mark 7 has a small circular shape, the shortest distance A from the center of the substrate alignment mark 6 to the pattern of the auxiliary mark 16 may be set as shown in Expression (1). (See FIG. 4).
A> r + Δ (1)
r: radius of mask alignment mark 7 Δ: maximum amount of displacement of the center position of each alignment mark 6, 7 assumed in the state before the start of alignment When the mask alignment mark 7 is square, formula (1) However, other mark shapes such as taking 1/2 of the diagonal length instead of the radius can be easily applied.
[0029]
As mentioned above, although the focus adjustment method and focus adjustment apparatus by this invention demonstrated embodiment as a part of the alignment apparatus in organic electroluminescent display manufacture, other devices, such as a glass substrate bonding apparatus (method) in liquid crystal display manufacture, are described. It can be applied to a flat panel display manufacturing apparatus.
[0030]
[Another embodiment]
<1> In the present embodiment described above, the auxiliary mark 16 is provided on the glass substrate 4. However, when the mask alignment mark 7 is smaller than the substrate alignment mark 6, an opening (through hole) is formed in the metal mask 5. An auxiliary mark may be provided.
[0031]
<2> When both the substrate alignment mark 6 and the mask alignment mark 7 are small with respect to the field of view of the imaging apparatus 1 and the sharpness value is small, auxiliary marks may be provided on both.
[0032]
<3> The auxiliary mark 16 may be a single pattern as in the above-described embodiment, or may be composed of a plurality of patterns. In this case, the pattern of the auxiliary mark 16 is preferably different in shape, size, etc. from the alignment marks 6 and 7 in order to prevent erroneous recognition with the alignment marks 6 and 7.
[0033]
<4> If the auxiliary mark 16 is made of the same material (chromium reflective film) as the substrate alignment mark 6, it can be manufactured at the same time as the substrate alignment mark 6, but the reflection between the substrate alignment mark 6 and the metal mask 5 is desirable. When the difference in rate is small, the contrast of the auxiliary mark 16 can be increased and the sharpness value can be increased by making the material of the auxiliary mark 16 have a large difference in reflectance from the metal mask 5. .
[0034]
【The invention's effect】
As described above, according to the present invention, the first alignment mark is set on one of the pair of aligned bodies that are opposed to each other with a predetermined interval, and the first alignment mark is paired with the other. The second alignment mark to be formed is set, and both the alignment is performed so that the deviation amount from the normal position of both marks in the image including both the alignment marks imaged by the imaging means is within a preset range. Prior to alignment to adjust the relative position of the body, in the focus adjustment method to focus each pair of aligned objects, an auxiliary mark is placed on one of the aligned objects close to the alignment mark. Then, the imaging means is operated while adjusting the distance between the imaging means and the object to be aligned, and the focal position is when the differential component of the video signal by the imaging means takes a maximum value.
[0035]
A first alignment mark set on one of the pair of aligned bodies opposed to each other at a predetermined interval; an auxiliary mark provided in the vicinity thereof; and Imaging means capable of imaging the second alignment mark set on the other alignment body, means for extracting a differential component of the image signal of the portion including the alignment mark imaged by the imaging means, and It is also a feature that the focus adjustment device is configured by providing a focus position for detecting the focal position where the differential component of the imaging signal takes a maximum value.
[0036]
According to these focus adjustment methods or apparatuses, even when the alignment mark of the alignment target is small, the differential component of the video signal is increased by adding the image of the auxiliary mark. False detection is reduced, focus adjustment can be performed reliably and easily, and reliability can be improved. Thereby, the effect that the alignment of a pair of to-be-aligned bodies, such as a glass substrate and a metal mask, can be performed with higher accuracy is obtained.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a schematic structure of an alignment apparatus. FIG. 2 shows each alignment mark, (a) is a cross-sectional view, and (b) is a captured image. FIG. 3 is a graph of a relationship between a sharpness value and a focus position. FIG. 4 is a bottom view showing the relationship between each alignment mark and auxiliary mark. FIG. 5 shows each conventional alignment mark, (a) is a cross-sectional view, and (b) is a captured image. That shows the graph of the relationship between the sharpness value and the focal point position
DESCRIPTION OF SYMBOLS 1 Image pickup means 4 One to-be-aligned body 5 The other to-be-aligned body 6 1st alignment mark 7 2nd alignment mark 16 Auxiliary mark k Means to detect a focus position t Means to extract a differential component

Claims (4)

One is a glass substrate on which an organic EL material is deposited through a metal mask having a vapor deposition opening to form a film and patterned, and the other is a metal having the vapor deposition opening. the setting of the first alignment indicia on the other side of the surface of the alignment member in one said pair of the alignment member is a mask, and the second forming the first alignment indicia paired to the other The registration mark is set, and the both alignment is performed so that the deviation amount from the normal position of both marks in the image including both the registration marks imaged by the imaging unit is within a preset range. Prior to alignment for adjusting the relative position of the body, a focus adjustment method for focusing each of the pair of aligned bodies,
The position of the imaging means with respect to the alignment object is adjusted by moving the imaging means, and the alignment mark of one or both of the alignment objects and the alignment object in one of the alignment objects are adjusted . wherein an auxiliary indicia provided in proximity to the other side the one of the alignment indicia on the surface of the Kakomeru preparative an and the second alignment indicia state surrounding the indicia for one alignment the size the alignment An operation step of the imaging means for imaging from one side of the body ;
The in-focus position of the imaging means with respect to each of the pair of aligned bodies is detected from the maximum value of the sharpness value based on the differential component of the video signal output by the imaging means according to the position of the imaging means. A focus adjustment method comprising a process.   The perspective adjustment of the imaging unit is performed by moving the position of the imaging unit with respect to the object to be aligned to a position away from a close position or a position close to a position away from the close position. 2. The focus adjustment method according to 1. One is a glass substrate on which an organic EL material is deposited through a metal mask having a vapor deposition opening to form a film and patterned, and the other is a metal having the vapor deposition opening. The first alignment mark set on the other surface of the alignment object in the alignment object of one of the pair of alignment objects that are masks, and the vicinity of the first alignment mark wherein the other side of the auxiliary mark is provided in a state surrounding the one of the alignment indicia said the surface, and the other of the alignment member to the size of the alignment member falls within a range surrounding the said auxiliary mark imaging means for imaging from one side of such a set second alignment indicia of the object to be aligned body,
A position adjusting unit of the imaging unit that adjusts a distance of the imaging unit with respect to the alignment target body by moving the imaging unit;
Means for extracting a differential component of the video signal output by the imaging means;
Means for calculating a sharpness value for the position of the imaging means based on the differential component;
A focus adjustment device comprising: means for detecting a focus position of the imaging means with respect to each of the pair of objects to be aligned from the maximum value of the sharpness value.   The focus according to claim 3, wherein the position adjusting unit moves the position of the imaging unit with respect to the alignment target to a position away from a close position or a position close to the distant position. Adjusting device.

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