JPS61100817A - Positioning method - Google Patents

Abstract

PURPOSE:To easily make accurate positioning, by scanning such two objects that contain the overlapped sections of their area type marks in their scanning areas by using two scanning lines. CONSTITUTION:Filters 10, condenser lenses 11, and half mirrors 14 are respectively arranged along the optical paths of lights sources 9 and diaphragms 13 and image forming lenses 12 are provided along reflecting optical paths. Luminous fluxes transmitted by the lenses illuminate two similar square marks 1R and 2R and another two similar square marks 2R and 2L on glass bases 1 and 2, respectively. Moreover, by respectively providing half mirrors 14 and image pickup tubes 15 along optical paths reflected by the bases 1 and 2, picked up images are displayed on a monitor TV 17 through camera control units 16. Therefore, picture images of the above-mentioned right and left marks 1R-2L separately taken by the image pickup tubes 15 are combined by means of a center wiper 100 and displayed in one monitor. In this case, video signals are inputted in a CPU18 and positioning is performed by performing relative position detection and driving a motor 19.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for aligning two objects, such as glass substrates for liquid crystals.

[Prior art]

Generally, transparent electrodes are used in various display boards including liquid crystal display boards, and these display boards are used in optical devices, electronic devices, dials of watches, large LCD TV displays, thermometers, etc. covers a wide range of fields. In such display boards, two substrates are used to encapsulate materials such as liquid crystal, and transparent electrodes are formed on each substrate, but the accuracy of the pattern of these transparent electrodes determines the performance of the product. It becomes more important.

Conventionally, this type of alignment has been carried out by printing an alignment mark M1 on one substrate and a similar mark M2 on the other substrate, as shown in FIG.
If 2 falls within the mark M1, it is determined that the two boards have been aligned, but this judgment is done by visual inspection, which is difficult to do, and therefore the work efficiency is low and the alignment accuracy is also hindered. .

〔the purpose〕

An object of the present invention is to eliminate the drawbacks of the above-mentioned conventional examples and to provide a highly accurate positioning method.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In FIG. 1, along the optical paths of light sources 9R and 9L, filters 10R and IOL, condenser lenses 11R and 11L, and half mirrors 14R and 14 are arranged to block infrared light, respectively.
Apertures 15R, 15L and imaging lenses 12R, 12L are arranged, respectively, along the optical path reflected by the half mirror 14R114L.
The light beams transmitted through 12L illuminate the glass substrates 1 and 2, respectively. Incidentally, since the glass substrate and mark used in this embodiment exhibit a high luminous intensity difference in reflected light with short wavelength illumination light, filters 10R and 10L that block infrared light are used. Furthermore, this illumination system employs a bright field illumination method. Bright-field illumination involves placing apertures 15R and 15L at the focal positions behind the imaging lenses 12R and 12L to form a telesend link optical system for the illumination light, and observing objects using specularly reflected light from the illumination light. It is a lighting method.

Half mirrors 14R, 14L and image pickup tubes 15R, 15L are arranged along the optical paths reflected by the substrates 1, 2, respectively, and the images taken by the image pickup tubes 15R, 15LK are sent via camera control units 16R, 16L. The image is taken out on the monitor television 17.

Here, images of the left and right marks separately photographed by the image pickup tubes 15R and 15LK are combined by the center wiper 100 and displayed on one monitor.

Additionally, the positions of the two scanning lines for each mark image can be adjusted separately and independently in the vertical direction of the monitor by an electrical processing section to be described later.

Now, the video signals from the image pickup tubes 15R and 15L are input to a central processing unit (cpσ) 18 that detects the relative positions of the substrates 1 and 2, as will be described later, and the motor 19 is activated according to the calculation results of the central processing unit 18. The substrates 1 and 2 are aligned by operating stage mechanisms (not shown) that are driven and hold the substrates 1 and 2, respectively.

Here, to explain the operation of the above configuration, the substrate 1.2 is first roughly aligned in advance, and similar square marks 1R and 2R and marks 1L and 2L are placed within the projection fields of the imaging lenses 12R and 12L, respectively. are arranged so as to overlap each other.

If a positional error occurs here, the mark image iR' on the substrate 1 will appear on the monitor and review 17 as shown in the upper part of FIG.
, IL' and the mark images 2R', 2L' on the substrate 2 are photographed with a misalignment. In order to simplify the explanation, the relationship between mark images I R1 and 2 R' will be described below.

As shown in FIG. 2(A), when the two scanning lines Sm and Sn of the video signal of the image are detected by the central processing unit in one day, the intensity of the reflected light at the position on each scanning line from the mark images 1ul and 2R1, respectively. Depending on the difference, a high voltage signal is obtained over a predetermined period of time.

That is, at least the mark 1R is reflective and translucent, and at least the mark 1L is reflective, and when illuminated from above, the reflected light reflects the marks IR and IR on the two substrates 1 and 2. In the area where 2R overlaps, the reflection from the mark 1R on the upper substrate 1 and the reflection from the mark 2R on the lower substrate 2 are added, and the highest light intensity is obtained. The intensity of the reflected light becomes weak in a portion where a mark is formed on only one of the two substrates (see FIG. 2 (Bl, (C)).

In other words, it is possible to clearly distinguish between the part where the marks IR and 2R on the two boards overlap, the part with the mark 2R on one side of the board, and the part with only the board, and the relative position of the two marks IR and 2R. You can check the exact location.

Here, the marks IR and 2R have a square shape as shown in FIG. 2 (Al), and each side intersects the mutually parallel scanning lines Sm and Sn of the video signal at an angle of 45 degrees. Note that if the intersection angle is 0° (or 90''), positional deviation in the Y direction cannot be detected; any other angle is fine, but if it is 45°, it will be detected in the X direction.

The detection t# degrees in the Y direction can be made equal.

The size of the square is 2a in each diagonal direction.
, 2b, the critical displacement at which the smaller square (which overlaps with the larger square) no longer intersects the fixed scanning lines Sm, Sn is Δ, and the scanning lines Sm, Sn
Taking into account the interval 21o, it is determined, for example, as follows.

That is, the condition that the upper left side of the mark image I R' intersects the scanning line am is Δ=a-! ! o1111...(1) Also, the condition that the lower left side of the mark image 1R' intersects the scanning line an is Δ=la...(2) Also, the mark image I RJ is in the horizontal direction and the vertical direction. As a condition that the mark image IL' does not protrude even if the mark image is displaced by 2Δ at a time, 2 degrees are calculated as follows. , b=6Δ.

Now - now the distance 11,1 detected by the two scanning lines Sm, Sn as shown in FIG. 2 (B><0)
2. Is.

1, J, 12', lJ, the alignment error ΔX, ΔY,
Δθ is determined as follows.

That is, regarding mark images 1R' and 2R' Ic, in the X direction,
If the errors in the Y direction are △XR and ΔYR, (ls -61) + (13'-11') ΔXx=
...(4) (A!1+ls)
C11'+ls')ΔYR:=□-...(5) Similarly, regarding mark images I L' and 2L',
The direction errors ΔXb and ΔYIJ are found, but the marks IR,
Letting R be the distance between 2R, IL, and 2L projected onto the imaging surface, ΔX, ΔY, and Δθ are determined as follows.

ΔY==□　　　−Φ・・(7) Next, FIG. 3 shows an actual example of video signal processing.

Reference numeral 22 denotes a left/right selector switch, which is used to detect the left and right mark positions with one detection system.

25 is a video amplifier, 24.25 is a level comparator, and the amplified video signal is binarized as shown in FIG. 2 (B).

26 is a synchronization separation circuit, 27 is a cursor counter, 28 is a digital comparator, and 29.31 is a cursor extraction circuit that displays two scanning lines Sm and an on the monitor 17. That is, the video signal input to the synchronization separation circuit 26 is extracted as a horizontal synchronization signal and a vertical synchronization signal, and is input to the cursor counter 27, where the number of pulses of the horizontal synchronization signal is counted. The counting data is sent to the digital comparator 28
The scanning line 8 inputted to and instructed by the arithmetic processing unit 58 in advance
A coincidence pulse is outputted from the digital comparator 28 at the time of coincidence with the position data of m. The cursor A extraction circuit 29 outputs one horizontal scanning line immediately after the coincidence pulse is generated as a cursorm scanning period signal. Also, delay circuit 3
0 and the cursor extracting circuit 51 outputs a scanning time signal for displaying the scanning line an at a certain time later than the cursor A.

Here, the frequency of the reference clock 52 is set so that the number of pulses represents the actual mark position information. For example, if the distance resolution is 10 μm and the image pickup tube of a television camera is % inch, then the clock frequency f is 55 x T [1-6 sec], where To is the effective horizontal scanning time.
where β is the magnification of the projection optical system, and if β=2.5, then f”=6.6 MHz.

Each output of the level comparators 24 and 25, each output of the cursor extraction circuit 29 and 51, and the clock pulse are AN
Through the D gate circuit 65, each position counter 5
4 to 57 are input.

The position counter 64 detects the mark image 1R at the cursor A.
The position data TAH1, TiH2 from the horizontal synchronizing pulse in the portion where the mark image 2R1 and 2R/ overlap are obtained, and the position counter 35 obtains the position data TAV1. TAV2 is obtained, and TBJ is similarly obtained from the position counter 36.

TBII2, TBvl, TBV from position counter 37
2 data are obtained.

These data are input to the arithmetic processing section 58 via the common path line. As a result, the relative position errors ΔX, ΔY, and Δθ as described above are determined.

In FIG. 5, 100 is a center wiper that electrically shifts the image on the monitor, 68 is an arithmetic processing section, and 59a to 59c are each X.

Y and θ-axis stepping motor controller, 40a~
40c are drive motors for the X, Y, and θ axes, respectively.

By the way, in the above-mentioned embodiment, when detecting the position using the scanning lines 8m and 8m, it was shown that the substrates 1 and 2 exist together and are scanned at the same time. It is also possible to store the scanning signal obtained by storing the scanning signal, and then compare it with the scanning signal obtained by loading the substrate 2 and scanning it.

That is, by the stage mechanism, first, the upper substrate 1 is
The marks IR and IL are set within the depth of the imaging lenses 12R and 12L, and the marks IR and IL enter the field of view of the monitor TV.Then, the lower substrate is sent on the stage, and then the imaging lenses 12R and 12L are moved by the stage's push-up mechanism. The marks 2R and 2L are placed within the field of view of the monitor television.

After the marks IR and IL enter the depth of the focusing lens, the position information of the marks IR and IL is stored until the marks 2R and 2L on the substrate 2 enter the field of view.

At this time, the scanning signal can be binarized at the threshold level L instead of the threshold level ■ shown in FIG. 2(B) (0).

Since the binarization of the scanning signal obtained when the substrate 2 is carried in and scanned is at the threshold level L as shown in Fig. 2 (B) and (C), when scanning with such a time difference is performed , the level for binarization is the same, and
There are advantages in that the number of level comparators H24 can be reduced, the processing process can be simplified, and information on the substrate 1 and information on the substrate 2 can be stored separately.

For example, even if alignment is not possible during the -th cycle of processing, if substrate 1 is fixed and the stage of substrate 2 is driven and alignment is performed, information on substrate 2 can be obtained only from marks 2R and 2L. , the second alignment can be performed.

By the way, in the above embodiment, the first. In addition to detecting reflected light from the second object, transmitted light may also be detected, and one object may be detected using reflected light and the other object may be detected using transmitted light. Note that the reflected light is not limited to specularly reflected light, and may be scattered light.

In addition, area-type marks are not limited to square marks, but also include other polygonal marks. A mark of an opening provided on the second object or equivalent thereto but transparent through the mark part,
It may be something that is reflected or absorbed in a non-marked area.

That is, it may be in a negative/positive (black and white inversion) relationship with the above embodiment.

An example of the output of the scanning signal in this case is shown in FIG. 4(B).

Note that the scanning is not limited to television scanning, and the object may be scanned with a laser or the like.

Also, 1st. The size relationship of the second marks is that one is larger,
It is not limited to the case where the other is small, and both may be of the same size. Note that the number of scanning lines is not limited to two, but may be six or more.

〔effect〕

As described above, according to the present invention, at least two scanning lines are used,
Not only can two objects be scanned so that the overlapping portions of the area-type marks on the two objects are included in the scanning area to perform accurate alignment, but since the area-type marks are area-type marks, rough adjustment is also easy. In particular, if a square mark is used, it will appeal to the senses and coarse adjustment will be extremely easy.

As described in the embodiment, if the output of the mark superimposing section becomes high, stable position detection can be performed even if noise such as dust enters the superimposing section and the output decreases slightly.

[Brief explanation of the drawing]

Fig. 1 is a diagram of an embodiment of a device using the present invention, and Fig. 2 (
A), (B), and (C) are explanatory diagrams of alignment using two scanning lines. Figure 3 is a diagram of an example of video signal processing. Figure 4 (A)
CB) is a diagram of an example of a different opening mark, and Figure 5 is a diagram of a conventional example.
. . . Image pickup tube 17 . . . Monitor Sm, 8n . . . [Phase] scanning line.

Claims (1)

[Claims] 1. In a method for aligning a first object and a second object, a first area-type mark is formed on the first object, and an area-type first mark is formed on the second object. scanning the first and second objects or their images with at least two scanning lines such that at least the scanning area includes an overlapping portion of both marks when viewed from a predetermined direction; A relative positional shift between the first object and the second object is detected by detecting a scanning signal from the object or its image and a scanning signal from the second object or its image. alignment method. 2. The alignment method according to claim 1, wherein the first and second marks are polygonal marks. 3. The positioning method according to claim 2, wherein the first and second marks are square marks inclined at 45 degrees with respect to the scanning line. 4. The alignment method according to claim 1, wherein the first and second objects or their images are simultaneously scanned. 5. The alignment method according to claim 1, wherein the first and second objects or their images are scanned with a time difference. 6. Bring in the first object before the second object, store the scanning signal obtained by scanning the first object or its image in advance, and store the scanning signal obtained by scanning when the second object is carried in. 6. The positioning method according to claim 5, wherein the positioning method is compared with a scanning signal. 7. Claim 6, wherein the level for binarizing the scanning signal is the same when the first object or its image is scanned in advance and when the second object is carried in and scanned.
Alignment method described in section. 8. The alignment method according to claim 1, wherein the scanning is performed using a scanning line of a television on which the first and second objects are imaged. 9. The alignment method according to claim 1, wherein at least one of the first and second marks is a mark placed on an object. 10. The positioning method according to claim 1, wherein at least one of the first and second marks is a mark consisting of an opening in an object. 11. The alignment method according to claim 1, wherein the first mark is at least translucent and reflective, and the second mark is at least reflective.