JPH0876103A - Aligning device for aligning marks - Google Patents

Abstract

PURPOSE: To make it possible to exactly find the coordinate values of both marks having good reflectivity and to execute exact positioning by attenuating illumination light to both marks and the regions in the peripheries thereof by the component corresponding to the difference of reflectivity, thereby lessening the difference between the levels of the reflected light of both marks. CONSTITUTION: A liquid crystal filter 8 disposed in an illumination system 42 has liquid crystals and a TFT substrate and an impression voltage V is impressed on the respective TFT elements of the TFT substrate by a driving circuit 8. The orientation of the liquid crystal molecules of the liquid crystal filter 8 corresponding to the TFT elements impressed with the impression voltage V is continuously changed according to the intensity of the electric fields which the TFT elements generate by the impressed voltage and, therefore, the transmittance of the liquid crystal filter 8 changes as well according thereto. The impression voltage V corresponding to the difference in the level is then impressed to the TFT elements corresponding to the aligning marks having the good reflectivity and the regions in the peripheries thereof by the driving circuit 8a. Consequently, these regions are inrradiated with the light attenuated in the transmittance of the regions of the liquid crystal filter 8 for the regions corresponding to the level difference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alignment device for aligning the alignment marks of two works in the assembly of component works such as color liquid crystal plates.

[0002]

2. Description of the Related Art Recently, various image display devices include
Liquid crystal panels or plates that display images in color are often used. FIG. 4 shows, as an example, constituent materials of the color liquid crystal plate 1 used in a viewfinder of a video camera. The color liquid crystal plate 1 is a color filter in which pixels G of three primary colors are arranged in a matrix on the surface of a glass plate 111.
11 and the TF corresponding to each pixel G on the surface of the glass plate 121.
The TFT substrate 12 on which the T element is formed includes marks M _C1 and M _C2 and marks M _T1 and M _T2 for alignment, respectively, in the margins at both ends of the color filter 11 and the TFT substrate 12. Has been done. The marks M _C1 and M _C2 are formed by depositing chrome, and the marks M _T1 and M _T2 are formed of the same material as the TFT element. Further, a UV curable adhesive 122 that is cured by ultraviolet rays is applied to the marginal area around the TFT substrate 12 except for the filling port (IN).

FIG. 5 shows the structure of the assembling apparatus of the color liquid crystal plate 1 described above, and the assembling procedure of the liquid crystal plate 1 will be described. The TFT substrate 12 is placed on the XY moving table 2, while the color filter 11 is adsorbed and held by the adsorption plate 3 made of quartz glass, and lowered by the Z moving mechanism (not shown) to approach the TFT substrate 12. , Stop at the appropriate gap position. Two image-receiving cameras with detection optical system 4
41a and 41b receive the marks M _C1 and M _T1 on the right side and the marks M _C2 and M _T2 on the left side, respectively, and each image signal is processed by the signal processing unit 5 to detect the XY coordinates of each mark. This coordinate data is input to the movement control unit 6 to move the XY movement table 2 in X or Y, and the mark M _T1 becomes M.
_C1 and the mark M _T2 are on M _C2 at a constant interval δ.
x (described in detail below). When the alignment on both sides is completed, the suction plate 3 is further lowered to press the lower surface of the color filter 11 against the UV curable adhesive 122, and the UV curable adhesive 122 is cured by irradiation with ultraviolet rays so that the both are adhered. Then, after the suction of the color filter 11 is released and the suction plate 3 is pulled up, the filling mechanism 7 fills the liquid crystal (LC) with the filling port (I
N) is injected into the interior, and necessary ITO electrode film, polarizing film, etc. are attached to complete the color liquid crystal plate 1.

FIG. 6 shows a schematic structure of the above-mentioned detection optical system 4 and a mutual positional relationship between the marks M _C and M _T. Figure 6
In (a), the detection optical system 4 includes the above-mentioned two image receiving cameras 41a and 41b, a white light source 421, and two relay lenses 422 and 42.
The illumination system 42 is composed of three, a half mirror 43, and a telecentric lens 44. Illumination light L _T from the light source 421 is collimated by the relay lens 422, focused by the relay lens 423, reflected by the half mirror 43, and again converted into parallel by the telecentric lens 44, and then the color filter 11 and the TFT substrate. The marks M _C1 and M _T1 on the right side and the reflected light L _{R on the} periphery of the mark 12 which are radiated perpendicularly to 12 are projected onto the image receiving camera 41a, and marks _{C C2} and M on the left side
The reflected light L _R of _T2 and its surroundings is received by the image receiving camera 41b. In FIG. 6B, the corresponding two marks M _C and M _T are aligned with each other at an appropriate distance δx in the X direction. The reason for performing the alignment with the interval δx in this way is that in the method of matching the two, when the two overlap, they are not clearly distinguished from each other, and therefore, accurate alignment is not performed. On the other hand, in the state before the alignment, the mark M _C is, for example, at the position of M _C '
The mark M _T is located, for example, at the position of M _T 'in the figure. Therefore, with respect to both marks M _C and M _T in the aligned state, a position deviation circle C is assumed with respect to the maximum range of the position deviation, and the respective radii are set to δx / 2, and the positions of both marks M _C and M _T are set. The matching interval δx is defined.

[0005]

As described above, since the mark M _C of the color filter 11 is made of chrome, its reflectance is quite good. On the other hand, the mark M _T of the TFT substrate 12 is formed of the same material as the TFT element, and there are various materials, but the reflectance is considerably low in any case. In addition, if the UV curable adhesive 122 is pressed, the UV curable adhesive 122 oozes and spreads, and the image is often blurred and unclear because it covers the mark M _T. Due to these, a large difference occurs in the level of the reflected light of both marks M _C and M _T. FIG. 7 shows an example of the relative level of the reflected light of both marks M _C and M _T , where the level of the mark M _C is very large.
It exhibits a large S / N ratio with respect to the reflected light from the glass plate 111.
On the other hand, the mark M _C has a very small level,
It is recognized that the light slightly protrudes between the reflected lights of the glass plate 121 or the UV curing adhesive 122, and the level difference between the reflected lights of the marks M _C and M _T is large. When both the marks M _C and M _T having a large level difference are received by the image receiving camera 41, if the sensitivity of the image receiving camera 41 is increased in order to clearly receive the low level mark M _T , the image of the mark M _C is displayed. Is saturated, and the XY coordinate values cannot be obtained accurately. Therefore, the illumination light L _T for the mark M _{C is} dimmed and the mark M _C is reduced.
_{For T} , it is necessary not to dim, and a neutral density filter is effective for this. However, in the case of using a normal optical filter, a filter that divides the regions of both marks M _C and M _T forming the interval δx and dims only the region of the mark M _C is necessary. It is not always easy to manufacture a simple neutral density filter. Moreover, since the reflection level of the mark M _T changes depending on the lot of the TFT substrate 12, it is necessary to replace the neutral density filter accordingly.
Optical filters have some drawbacks. The present invention has been made in view of the above, and is provided on any two workpieces,
Targeting two alignment marks having a large difference in reflectance, the alignment mark having a good reflectance is provided with means for reducing the illumination light corresponding to the difference in reflectance between the two. An object is to provide an alignment device.

[0006]

SUMMARY OF THE INVENTION The present invention is an alignment mark alignment device, which is provided at both ends of two upper and lower workpieces, and has two alignment marks corresponding to each other. , When there is a large difference between the respective reflectances, the alignment mark having a good reflectance and the area around it are illuminated by dimming illumination light by an amount corresponding to the difference. The liquid crystal filter having the above is arranged in the illumination system, and a drive circuit for applying an applied voltage to each TFT element of the TFT substrate is provided.

[0007]

In the above alignment apparatus, the liquid crystal filter arranged in the illumination system has a liquid crystal and a TFT substrate, and T
An applied voltage is applied to each TFT element on the FT substrate by a drive circuit. In the liquid crystal of the liquid crystal filter, the orientation of the liquid crystal molecules corresponding to the TFT element to which an applied voltage is applied continuously changes according to the electric field strength generated by the TFT element due to the applied voltage. Also changes continuously. The application of the applied voltage to all the TFT elements is stopped in advance, two alignment marks are imaged by the image receiving camera, the image signal is processed by the signal processing unit, and the level difference between the light receiving levels of both alignment marks is calculated. Ask. When a driving circuit applies an applied voltage corresponding to the level difference to the alignment mark having a good reflectance and the TFT element corresponding to the peripheral region, the transmittance of the liquid crystal filter region with respect to this region becomes The illumination light is reduced by the amount corresponding to the level difference, and the alignment mark having a good reflectance and the area around it are irradiated. On the other hand, the alignment marks with poor reflectance are not dimmed, so the level difference between the two reflected lights becomes smaller or disappears, and both marks are clearly imaged by the image receiving camera, and their XY coordinates The value is calculated accurately,
The two workpieces are aligned correctly.

[0008]

1 is a block diagram of an embodiment of an alignment apparatus of the present invention, FIG. 2 is an exploded view of an embodiment of a liquid crystal filter 8 and a curve diagram of its transmittance, and FIG. 3 is a view of alignment. FIG. 8 is an explanatory view of the operation of the liquid crystal filter 8.

In FIG. 1, a detection optical system 4'according to the present invention is different from the detection optical system 4 shown in FIG.
The liquid crystal filter 8 is inserted between the relay lenses 412 and 413 of the illumination system 41.
and a microprocessor (MPU) 9 having a memory (MEM) 9a. Both image receiving cameras 41a, 41b
The conventional signal processing unit 5 is connected to the MPU 9.

In FIG. 2A, the liquid crystal filter 8 comprises, in order from the top, a polarizing film A81 and an ITO transparent electrode 82 on the upper surface.
1. A glass plate 82 having 1, a TFT substrate 83 having a TFT element 831 formed on its upper surface, a polarizing film B84, and a liquid crystal (LC) injected between the glass plate 82 and the TFT substrate 83,
After the glass plate 82 and the TFT substrate 83 are separated by an appropriate gap and LC is injected and sealed, the upper and lower layers are adhered to each other. The polarizing film A81 and the polarizing film B84 are arranged such that their polarization planes are perpendicular to each other, and the transparent electrode 821 is grounded. The LC is a TN type. Figure 2 (b) shows the TN
An example of a change curve of the light transmittance of the liquid crystal filter 8 constituted by the LC type is shown, the horizontal axis is the effective value v _rms of the applied voltage v to the TFT element 831 and the vertical axis is the light transmittance (%). When the applied voltage v _rms is 2 V or less, the transmittance is 100%. When the applied voltage v _rms is more than this, the transmittance drops to almost 0% at about 4 V.
The slope of the transmittance or the steepness of the curve depends on the thickness of the LC, the curves shown are for a thickness of about 9 μm.
In order to turn on and off the light rapidly, it is preferable to be steep, but in the case of the present invention, in order to obtain a desired transmittance for the illumination light L _T , a gentle inclination is easier to control. The thickness of the LC having such an inclination angle is selected, the transmittance characteristic with respect to the applied voltage v is measured, and the measured data is M
Store in EM9a.

The positioning procedure will be described below with reference to FIGS. 1 to 3 by taking the color liquid crystal plate 1 of FIG. 4 as an example. In FIG. 1, the application of the applied voltage v to all the TFT elements 831 is stopped and the transmittance of the liquid crystal filter 8 is set to 100%. Each mark on the appropriate color filter 11 and the TFT substrate 12 is used as a sample, and the corresponding two marks M _C and M _T are received by the image receiving camera 41. In this case, as above,
It is assumed that the reflectance of the mark M _C is good, the reflectance of the mark M _{T 2} is not good, and there is a large difference between the reflectances of the two. Figure 3 (a)
Indicates each image of the sample mark received by both image receiving cameras 41a and 41b, and the image of the image receiving camera 41a has a boundary line x ₁
Marks M _C1 and M _T1 are scattered in the misalignment circles C in the regions S ₁ and S ₂ on both sides of the image. Similarly, the image of the image receiving camera 41b is
The marks M _C1 and M _T1 are scattered in the misaligned circles C in the regions S ₃ and S ₄ on both sides of the boundary line x ₂ . Both receiver cameras 41
The image signals of a and 41b are processed by the signal processing unit 5 to obtain the level difference between the light receiving levels of the marks M _C and M _T on either side or the average value of the level differences between the two sides, and this data is stored in the MEM 9a. Remember. Further, the X coordinate data of the boundary lines x ₁ and x ₂ are stored in the MEM 9a in advance. In aligning the color filter 11 and the TFT substrate 12,
The coordinate data of the boundaries x ₁ and x ₂ stored in the MEM 9a, the level difference data of both marks M _C and M _T , and the measured data of the transmittance characteristic are read out by the MPU 9, and the applied voltage corresponding to the level difference is read out. Control data for the TFT element 831 such as v _s is created and passed to the TFT drive circuit 8a. In the TFT drive circuit 8a, when the applied voltage v _s is applied to each TFT element 831 corresponding to the regions S ₂ and S ₃ based on the control data, the orientation of the liquid crystal molecules corresponding to these is applied voltage v _s. According to Fig. 3 (b)
As shown by hatching in both areas S of the liquid crystal filter 8,
The transmittance of the portion corresponding to ₂ and S ₃ is reduced by the amount corresponding to the level difference. However, in the figure (b), the boundary lines x ₁ and x ₂ are indicated by Z coordinates z ₁ and z. From the above, the illumination light L _T from the light source 421
Is partly dimmed by the liquid crystal filter 8 so that both areas S ₂ ,
The reflected light of both marks M _C and M _T irradiated on S ₃ is shown in FIG.
As shown in (c), the level difference becomes smaller and
The images are clearly received by 41a and 41b respectively, and the XY coordinate values of both marks M _C and M _T are accurately detected by the signal processing unit 5, so that the color filter 11 and the TFT substrate 12 are properly aligned.

In the above embodiment, the color liquid crystal plate 1 is used.
However, the present invention is not limited to this, and both alignment marks can be applied to any two workpieces that have two alignment marks that have a large difference in reflectance and are appropriately separated. The difference in the level of the reflected light is reduced so that both are clearly received and the alignment can be performed correctly.

[0013]

As described above, the alignment apparatus according to the present invention is configured by disposing the liquid crystal filter in the illumination system of the detection optical system and providing the drive circuit for each TFT element of the liquid crystal filter. When there is a large difference in the reflectance between the two corresponding alignment marks provided on each of the workpieces, the illumination light for the marks with good reflectance and the surrounding area is reduced by the liquid crystal filter by an amount equivalent to the large difference. Light is emitted, and the level difference of the reflected light of both marks is reduced to clearly receive the image on the image receiving camera.
The effect that each coordinate value is accurately obtained and the correct alignment can be achieved has a great effect.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of an alignment apparatus of the present invention.

FIG. 2 is an exploded view of an example of a liquid crystal filter and a curve diagram of its transmittance.

FIG. 3 is an explanatory view of the action of the liquid crystal filter in alignment.

FIG. 4 is a surface view of constituent materials of a color liquid crystal plate used in a viewfinder of a video camera.

FIG. 5 is a schematic configuration diagram of a device for assembling a color liquid crystal plate.

FIG. 6 is a schematic configuration diagram of a detection optical system and an explanatory diagram of a mutual positional relationship between two marks.

FIG. 7 is a waveform diagram showing an example of relative levels of reflected light of two marks.

[Explanation of symbols]

1 ... Color liquid crystal plate, 11 ... Color filter, 111 ... Glass plate, 12 ... TFT substrate, 121 ... Glass plate, 122 ... UV curing adhesive, 2 ... XY moving table, 3 ... Suction plate, 4 ... Detection optical system, 4 '... Detection optical system according to the present invention, 41a, 41b
… Image receiving camera, 42… Illumination system, 421… White light source, 422, 423
... relay lens, 43 ... half mirror, 44 ... telecentric lens, 5 ... signal processing unit, 6 ... movement control unit, 7 ... filling mechanism, 8 ... liquid crystal filter, 81 ... polarizing film A, 82 ... glass plate, 821 ... ITO thin film electrode, 83 ... TFT substrate, 831 ...
TFT element, 84 ... Polarizing film B, 8a ... Driving circuit, 9 ... Microprocessor (MPU), 9a ... Memory (MEM),
M _C , M _T ... Alignment mark, M _C ', M _T ' ... Misaligned alignment mark, LC ... Liquid crystal, C ... Misaligned circle, δx ...
Alignment interval of alignment marks, S ₁ , S ₂ , S ₃ , S ₄ ... Region, x ₁ , x ₂ , z ₁ , z ₂ ... Boundary of each region, v ... Applied voltage, v _rms ... Applied voltage Effective value of.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H01L 21/027 21/68 F

Claims (1)

[Claims] 1. An illumination from a light source for two alignment marks which are provided at both ends of an upper work and a lower work respectively and which correspond to each other and are aligned at appropriate intervals. Telecentric light through half mirror
An illumination system that converts the parallel illumination light into parallel illumination light by a lens and irradiates the alignment plates that are superposed at a constant gap vertically to each other, and two alignment marks at both ends of the illumination system. Detection optical system having an image receiving camera of
And a signal processing unit for processing the image signals of both of the image receiving cameras, a good reflectance is obtained when there is a large difference in reflectance between the corresponding two alignment marks. A liquid crystal filter having a liquid crystal and a TFT substrate for illuminating the alignment mark and its surrounding area by dimming the illumination light by an amount corresponding to the difference is disposed in the illumination system. T
An alignment mark alignment device comprising a drive circuit for applying an applied voltage to each TFT element of an FT substrate.