JPH10213522A - Substrate inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform stable substrate observation even if the vibration of a substrate is not sufficiently controlled by always displaying a substrate image having a high focusing degree at the time of outputting a timing signal in the manufacturing prosess for a large substrate such as a liquid crystal display. SOLUTION: When the focusing mechanism of an optical microscope 1 is fixed in a reference focus position for the observed surface of a sample, the wave form 35 of a focusing signal is displayed based on a positional relationship between an objective lens and a vibrated glass board. An image fetching trigger signal 36 is produced matching a focusing time appearing in the focusing signal 35 fetched by a timing generator, an image from a photographing device 3 is fetched in an image storage device 4 by the timing of the trigger signal 36 and this stored image is displayed and thus a still image having a high focusing degree is obtained to be used for observation of the substrate. Thus, even for observation of high magnification where the vibration of the glass board is not suppressed, since the image at the time of focusing is displayed as a still image, stable substrate observation is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate inspection apparatus used in a process of manufacturing a substrate such as a liquid crystal display (LCD) and a plasma display panel (PDP).

[0002]

2. Description of the Related Art Glass substrates used in the manufacturing process of devices such as liquid crystal displays have recently been increasing in size.
It becomes more and more flexible as the device is made thinner, and may be affected by vibration when handled in a downflow type clean room.

[0003] In such a glass substrate inspection apparatus, when performing high-magnification observation with a microscope, it is particularly susceptible to vibration, and stable observation may be difficult.

Conventionally, stable observation at high magnification has been realized by holding the glass substrate so as not to vibrate. For example, there is a method of suppressing vibration by vacuum-adsorbing a glass substrate over a large area.

FIG. 6 is a diagram showing a schematic configuration of a conventional glass substrate holding device. In this glass substrate holding device, the glass substrate support 1 on the upper surface of the glass substrate mounting table 101
The glass substrate 103 is placed on the substrate 02.

The glass substrate 103 placed on the glass substrate support 102 is illuminated by a transmission illumination device 105 provided at the bottom of a glass substrate transfer device insertion space 104,
An image is taken by an observation means (not shown), and the image is provided for observation.

[0007]

In the case of the apparatus as shown in FIG. 6, an arm for mounting the glass substrate 103 on the glass substrate mounting table 101 is housed.
In order to allow the glass substrate 103 to be sufficiently observed with the use of the glass substrate 104, it is necessary to provide the glass substrate transfer device insertion space 104.

However, when such a space 104 is provided, it may be difficult to adopt a configuration capable of holding the glass substrate 103 over a wide area, and the vibration of the glass substrate 103 cannot be sufficiently suppressed. There is.

In such a case, if vacuum suction is performed to sufficiently hold the glass substrate, adverse effects such as electrostatic breakdown may occur. The present invention has been made in view of such circumstances, and in a manufacturing process of a large-sized substrate such as a liquid crystal display, a substrate that enables stable substrate observation even when vibration of the substrate cannot be sufficiently suppressed. It is an object to provide an inspection device.

[0010]

According to a first aspect of the present invention, there is provided a substrate inspection apparatus for inspecting a large substrate used in a process of manufacturing a device such as a flat display or a semiconductor element. The imaging means, the microscope means for forming an image of the substrate on the imaging surface of the imaging means, and the microscope means for controlling the substrate image so as to be in focus. A focusing unit that outputs a focus signal; an image storage unit that stores an image signal of a board image captured by the imaging unit; a display unit that displays an image signal stored in the image storage unit; Timing generating means for outputting a timing signal for capturing an image signal from the imaging means to the image storage means in accordance with a timing at which the degree of focusing of the substrate image becomes high based on the focusing signal. An inspection apparatus.

According to a second aspect of the present invention, in the first aspect of the present invention, a period of a timing at which the degree of focusing of the substrate image becomes high is detected, and a shutter timing in the imaging means is detected. This is a substrate inspection apparatus provided with a control unit that performs control based on a cycle.

Further, the invention corresponding to claim 3 is the substrate inspection apparatus according to claim 2, wherein the control means controls the shutter timing so as to be shorter than the detected cycle. (Action) Therefore,
First, in the substrate inspection apparatus according to the first aspect of the present invention, a substrate image is captured by the imaging unit.

This substrate image is enlarged to a predetermined size by the microscope means, and is formed on the imaging surface of the imaging means. At the time of this image formation, focusing is performed by focusing means, and the focus position is fixed.

Here, when the substrate is vibrating, although the substrate is focused once, the position of the substrate moves up and down near the true focal point, and the image is blurred and stable observation becomes difficult.

In order to prevent this, the following processing is performed. That is, first, after the focusing position is fixed, the focusing unit outputs a focusing signal indicating the degree of focusing of the substrate image.

Based on the focus signal, a timing signal is output from the timing generation means in accordance with the timing at which the degree of focus of the substrate image becomes higher. When this timing signal is input to the image storage means, the image storage means takes in the image signal from the imaging means.

Since the display means displays the image signal stored in the image storage means, the display means displays a substrate image having a high degree of focus at the time when the timing signal is output. It will always be displayed.

Further, the substrate inspection apparatus according to the second aspect of the present invention operates in the same manner as the first aspect of the present invention, and detects the period of the timing at which the degree of focusing of the substrate image becomes high, and captures the image. Shutter timing in the means
Control is performed based on the detected cycle. Therefore, a substrate image with a high degree of focus can be displayed more reliably without blurring.

Further, in the substrate inspection apparatus according to the third aspect of the present invention, in addition to the same operation as the second aspect of the invention, the control means makes the cycle of the shutter timing shorter than the detected cycle. Control.

[0020]

Embodiments of the present invention will be described below. (First Embodiment of the Invention) FIG. 1 is a block diagram showing an example of a substrate inspection apparatus according to a first embodiment of the present invention.

This substrate inspection apparatus is an apparatus for inspecting a glass substrate 8 supplied to a liquid crystal display manufacturing process. As shown in FIG. 1, an optical microscope 1 having automatic focusing means, and an automatic focusing control apparatus 2 and an imaging device 3 having a high-speed shutter function. Further, the board inspection device includes an image storage device 4 that stores an image signal of an observation image of the optical microscope 1 obtained by the imaging device 3, a display device 5 that displays the image signal stored by the image storage device 4, A timing generator 6 for generating a timing for fetching an image signal into the image storage device 4 by using a focusing signal of the automatic focusing control device 2, and a control device 7 for controlling each part and adjusting the operation thereof. I have.

Here, the automatic focusing control device 2 is configured to control the automatic focusing means and to store the reference focusing position. The imaging device 3 is composed of a CCD camera or the like, and its shutter function is based on a so-called electronic shutter.

Next, the operation of the substrate inspection apparatus according to the embodiment of the present invention configured as described above will be described.
First, when the glass substrate 8 as a sample vibrates on a glass substrate holding device (not shown), as shown in FIG.
Vibrates mainly in the focusing direction of the optical microscope.

FIG. 2 is a view showing a state in which the glass substrate vibrates on the glass substrate holding device. The focusing operation using the automatic focusing means of the optical microscope 1 is usually performed when the focusing mechanism of the optical microscope is mechanically operated on the observation surface of the sample and a signal indicating that the focusing is performed is detected. The operation of the focusing mechanism is stopped. The position of this focusing mechanism is defined as a reference focusing position. Also,
Even when the glass substrate 8 is vibrating, a certain degree of focusing has been performed at this reference focusing position, and a signal output from the automatic focusing control device 2 in this state is also simply referred to as a focusing signal. Various methods can be used for focusing by the automatic focusing unit. In the present embodiment, focusing is performed by a method using a contrast value.

In the present embodiment, a case is considered where the glass substrate 8 as a sample is vibrating during observation. As shown in FIG. 2A, the glass substrate 8 to be observed is bent downward 32 due to vibration, placed at the center 33 of the amplitude, and moved upward due to vibration with respect to the objective lens 31 of the optical microscope. The sagging state 34 is repeated.

Therefore, when the focusing mechanism of the optical microscope 1 is fixed at the reference focusing position with respect to the observation surface of the sample, the objective lens 31 and the vibrating glass substrate 8/32 /
Focus signal waveform 3 determined by the positional relationship with 33/34
5 is as shown in FIG.

Here, the glass substrate 8/32/33/34
Reciprocates in the quasi-focusing direction, the point at which the automatic focusing control device 2 is most focused is, as shown in FIG.
Appear at an interval of one half of the oscillation period of. That is, the period of the timing at which the degree of focusing becomes high is one half of the vibration period of the glass substrate 8.

FIG. 3 is a diagram showing an example of a waveform of a focus signal and a waveform of an image capture trigger signal generated in synchronization with the focus signal. After fixing the reference focus position in the optical microscope 1, a waveform 35 of a focus signal as shown in FIG. 3A is taken into the timing generator 6 from the automatic focus control device 2.

In the timing generator 6, an image capture trigger signal 36 is generated in accordance with the in-focus time periodically appearing in the captured focus signal 35. That is, the focus signal is converted into a signal form suitable for the trigger for capturing the image signal, and the trigger signal 3 output at the time of focusing
It becomes 6.

The trigger signal 36 from the timing generator 6
The image storage device 4 that has received the image signal stores the image signal from the imaging device 3 at that time and displays it on the display device 5. The observation image captured by the image capture trigger signal 36 is displayed as a still image on the display device 5 by the image storage device 4 until the next image capture trigger signal is input. That is, each time the image capture trigger signal 36 is input, the still image on the display device 5 is updated.

The high-speed shutter used in the image pickup apparatus 3 of the present embodiment is about 60 Hz, and the vibration of the glass substrate 8 in this embodiment is usually about 40 Hz or less. A well-focused image can be captured.

As described above, in the board inspection apparatus according to the embodiment of the present invention, the timing generator 6 adjusts the image capture trigger signal in accordance with the focus point that appears in the waveform 35 of the captured focus signal. 36, the image from the imaging device 3 is taken into the image storage device 4 at the timing of the trigger signal 36, and the stored image is displayed. Images can be obtained.

Therefore, even in high-magnification observation when vibration of the glass substrate cannot be suppressed, the image at the time of focusing is displayed as a still image on the display device, so that stable substrate observation can be performed. . (Second Embodiment of the Invention) FIG. 4 is a block diagram showing an example of a substrate inspection apparatus according to a second embodiment of the present invention.
The same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted.

In this board inspection device, the optical microscope 1, the automatic focusing control device 2, the imaging device 3, the display device 5, and the timing generator 6 'configured in the same manner as in the first embodiment.
And an image storage device 4 ', a shutter switch 43, a frequency counter 45, and a control device 7 are provided. In this embodiment, the glass substrate 8
A glass substrate holding device 41 and a glass substrate holding control device 42 for holding the substrate are shown.

Note that the automatic focusing control device 2, the timing generator 6 ', the frequency counter 45, the glass substrate holding control device 42, the shutter switching device 43, and the display switching device 44 are connected to the control device 7 for data transfer. It is connected to a data bus line 46.

The shutter switch 43 switches a shutter speed in a shutter function of the image pickup device 3. The switching control is performed based on a command from the control device 7.

The image storage device 4 'comprises an image storage section 49 and a display switch 44. When the image storage unit 49 receives the image capture trigger signal 53 from the timing generator 6 ′, the image storage unit 49 captures and stores the image signal output from the imaging device 3 at that time. Further, the captured image signal is transmitted to the next image capturing trigger signal 53.
Until the display switch 44 is received.

The display switching unit 44 outputs to the display device 5 either the image signal from the image storage unit 49 or the image signal directly from the imaging device 3. Switching between the two signals is performed based on a display selection signal from the control device 7.

The glass substrate holding device 41 holds the glass substrate 8
And the position of the glass substrate 8 can be changed according to the observable visual field of the optical microscope 1.
In order to control the operation of the glass substrate holding device 41,
A glass substrate holding control device 42 is provided, and information on the position of the glass substrate holding device 41 is managed by the glass substrate holding control device 42 as coordinate data. The coordinate data is input from the glass substrate holding controller 42 to the controller 7.

The timing generator 6 'includes a waveform 35 of a focus signal from the automatic focus control device 2 similar to that of the first embodiment, and a
2, and the shutter speed selection signal which is output to the shutter switch 43 by the control device 7 originally. As the shutter speed selection signal, a signal corresponding to the case where the control device 7 does not actually switch the shutter speed is input.

When the waveform 35 of the in-focus signal is input, the timing generator 6 ′ converts the waveform of the in-focus signal synchronous waveform signal 52 corresponding to the peak of the in-focus signal periodically appearing in the waveform 35. Generated and input to the frequency counter 45.

Further, upon receiving the coordinate data and the selection signal from the control device 7, the timing generator 6 'receives the focus signal synchronous waveform signal 52 generated at the next timing.
Is output to the image storage device 4 ′ as an image capture trigger signal 53.

The frequency counter 45 measures the frequency of the focus signal periodically appearing in the waveform 35 of the focus signal based on the focus signal synchronization waveform signal 52 input from the timing generator 6 '. The data is input to the control device 7 as frequency data.

The control device 7 is composed of a computer such as a personal computer or a work station.
6, a CPU 47 for executing each process, and a memory 4 for storing a control program for each process and also serving as a work area for the CPU 47.
8 is provided. Although not shown, a man-machine interface is connected to the control device 7 so that various setting inputs and instruction inputs can be performed.

The controller 7 receives the coordinate data from the glass substrate holding controller 42 and the frequency data from the frequency counter 45. After the frequency data becomes substantially constant, the frequency data is also stored. And glass substrate 8
Is determined, and a shutter speed selection signal is output to the shutter switch 43 so as to capture an image at a shutter speed faster than a half of the vibration period. On the other hand, coordinate data is output to the timing generator 6 ′, and a signal is output at the same timing as the output of the shutter speed selection signal to the shutter switch 43. The shutter speed selection signal outputs a signal corresponding to the shutter speed selection signal to the timing generator 6 'even when the shutter speed is not actually switched.

Further, the control device 7 outputs a display selection signal to the display switch 44 when an instruction is input from the man-machine interface or a predetermined condition is satisfied. In a normal setting, when the glass substrate 8 is vibrating,
When the glass substrate is observed and when the substrate is moved during the same substrate observation, the image stored in the image storage unit 49 is displayed, and at other times, the display is switched to display the direct signal from the imaging device 3.

Next, the operation of the substrate inspection apparatus according to the embodiment of the present invention configured as described above will be described with reference to FIGS.
This will be described with reference to FIG. FIG. 5 is a diagram showing the timing of each operation in the present embodiment.

The natural frequency of the glass substrate 8 varies depending on the size, thickness and vibration mode, but is up to about 100 Hz. In practice, the frequency is often about 40 Hz or less. Here, for the sake of explanation, it is assumed that the glass substrate 8 is oscillating with a frequency f [Hz] on the glass substrate holding device.

It is assumed that the observation image of the optical microscope 1 obtained by the imaging device 3 is displayed on the display device 5 through the display switching device 44, and as a result, it is determined that the observation is difficult due to vibrations. The inspector sends the display switch 4 to the control device 7.
4 is switched to the output from the image storage unit 49.

Next, when a control signal is sent to the automatic focusing control device 2 via the data bus line 46, the focusing mechanism of the optical microscope 1 is controlled so as to be at the reference focusing position on the observation surface. Since the glass substrate is vibrating and the focusing mechanism of the optical microscope 1 is fixed at the reference focusing position, the focusing apparatus as shown in FIG. A waveform 35 of the focus signal is generated, and the focal point periodically appears.

The frequency of the focal point is measured by a frequency counter 45, and the data bus line 46 is used as frequency data.
Is sent to the control device 7 through The control device 7 determines whether or not it is necessary to switch the shutter of the imaging device 3 to a higher speed shutter based on the value of the frequency data. Data bus line 46
Through the shutter switch 43.

For example, when the glass substrate 8 is vibrating at the frequency f [Hz], the frequency at which the focus signal appears is 2f [H].
z]. In order to improve the resolution of the observation surface moving at a cycle of 2f [Hz], for example, shutter speed <1 /
(10 × 2f [Hz]) A high-speed shutter speed of [sec] is selected, and the shutter switch 43 sets the imaging device 3
Is switched. The cycle of the shutter speed is preferably at least １ ／ or less of the oscillation cycle of the glass substrate 8.

At the same time, the image output signal of the display switching unit 44 is switched to the image signal from the image storage unit 49. The image signal obtained by the imaging device 3 is always input to the image storage unit 49, but is captured as a still image only when the image capture trigger signal 53 generated by the timing generator 6 ′ is stored in the image storage unit 49. It is when it is input.

The image capture trigger signal 53 is generated when the observation area is changed, that is, when the coordinate data from the glass substrate holding controller 42 is changed. And is generated in the timing generator 6 ′ when the selection signal 54 is input from the control device 7. That is, after the movement of the glass substrate 8, its vibration mode is analyzed, and after the shutter speed is switched based on this, the image capture trigger signal 53 is generated as shown in FIG.

In order to ensure that still image capture is performed, after the shutter switching determination is made in the control device 7, the selection signal 54 is output regardless of the actual switching instruction to the shutter switching device 43.
Is input to the timing generator 6 '.

The generation of the coordinate data change detection signal 51 shown in FIG. 5 will be described. First, the difference between the coordinate data input to the timing generator 6 'through the data bus line 46 is as follows.
′. For example, a difference between certain coordinate data and coordinate data after a lapse of a predetermined time is obtained. If the difference is not 0, the coordinate data has changed. Therefore, when this data difference occurs, a coordinate data change detection signal 51 is generated. Is done.

Further, although not particularly shown, a rising signal is generated in the timing generator 6 'even after the selection signal 54 is inputted, and the rising signal and the coordinate data change detection signal 51 are focused on. The image capture trigger signal 53 is generated as described above by taking the logical product with the signal synchronization waveform signal 52. After the image capture trigger signal 53 is generated, the rising signal becomes 0 again.

The image capture trigger signal 53 generated by the timing generator 6 'is input to the image storage section 49, and the image signal from the imaging device 3 is captured as a still image. The captured still image is displayed on the display device 5 through the display switch 44 until the next image is captured or the display is switched.

As described above, the board inspection apparatus according to the embodiment of the present invention has the same configuration as that of the first embodiment, and also switches the shutter speed based on the frequency data by the control device 7. As a result, the same effect as that of the first embodiment can be obtained, and a substrate image with a high degree of focus can be displayed more reliably.

Further, in the present embodiment, by controlling the cycle of the shutter timing to be shorter than the cycle of detecting the focal point, a secure focused image is ensured. However, the present invention is not limited to this. It is not something that can be done. For example, the present invention can be applied to various cases, such as opening a shutter and taking in an image signal at a focus point predicted from a focus detection cycle.

The present invention is not limited to the above embodiments, but can be variously modified without departing from the gist thereof. Further, in the present embodiment, the case of a glass substrate in the case of a liquid crystal substrate or a PDP has been described.
The present invention is not limited to this, and can be applied to inspection and observation of other substrates such as a silicon wafer. For example, a silicon wafer used for a semiconductor device is currently a large 8-inch wafer, and a next-generation 12-inch wafer will be used in the next generation. These are suitable for the purpose of the present invention. In recent years, a flat display in which a plasma panel and a liquid crystal panel are overlapped with each other has been developed, but it goes without saying that the present invention can be applied to a substrate of such a device.

Further, the method described in the embodiment may be a program that can be executed by a computer, for example, a storage medium such as a magnetic disk (floppy disk, hard disk, etc.), an optical disk (CD-ROM, DVD, etc.), a semiconductor memory, etc. And can also be transmitted and distributed via a communication medium. A computer that implements the present apparatus reads a program recorded on a storage medium, and executes the above-described processing by controlling the operation of the program.

[0063]

As described above in detail, according to the present invention, an image is stored at the time when the degree of focusing is high, and the stored image is displayed. Therefore, in the process of manufacturing a large-sized substrate such as a liquid crystal display. Even if the vibration of the substrate cannot be sufficiently suppressed, it is possible to provide a substrate inspection apparatus that enables stable substrate observation.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an example of a substrate inspection apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a state in which a glass substrate vibrates on a glass substrate holding device.

FIG. 3 is a diagram illustrating an example of a waveform of a focus signal and a waveform of an image capture trigger signal generated in synchronization with the focus signal.

FIG. 4 is a configuration diagram showing an example of a board inspection device according to a second embodiment of the present invention.

FIG. 5 is an exemplary view showing the timing of each operation in the embodiment.

FIG. 6 is a diagram showing a schematic configuration of a conventional glass substrate holding device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical microscope 2 ... Automatic focusing control apparatus 3 ... Image pickup apparatus 4 ... Image storage apparatus 5 ... Display apparatus 6, 6 '... Timing generator 7 ... Control apparatus 8 ... Glass substrate 31 ... Objective lens 32 ... Downward by vibration Deflected state 33 ... State at the center of amplitude 34 ... Deflected state due to vibration 35 ... Waveform of focus signal 36 ... Image capture trigger signal 41 ... Glass substrate holding device 42 ... Glass substrate holding control device 43 ... Shutter switcher 44 Display switcher 45 Frequency counter 46 Data bus line 49 Image storage unit 51 Coordinate data change detection signal 52 Focusing signal synchronous waveform signal 53 Image capture trigger signal 54 Selection signal

Claims (3)

[Claims] 1. A substrate inspection apparatus for inspecting a large substrate used in a manufacturing process of a device such as a flat display or a semiconductor element, comprising: an imaging unit; and a microscope for forming an image of the substrate on an imaging surface of the imaging unit. Means for controlling the microscope means to focus the substrate image, a focusing means for outputting a focus signal indicating a degree of focusing of the substrate image after fixing a focus position, and an image taken by the imaging means Image storage means for storing an image signal of the substrate image, display means for displaying the image signal stored in the image storage means, and focusing of the substrate image based on a focus signal from the focusing means. Timing generating means for outputting a timing signal for capturing an image signal from the imaging means to the image storage means in accordance with the timing at which the degree becomes high. Board inspection equipment. 2. A control unit for detecting a period of a timing at which the degree of focusing of the substrate image becomes high, and controlling a shutter timing of the imaging unit based on the detected period. Item 2. The substrate inspection apparatus according to Item 1. 3. The substrate inspection apparatus according to claim 2, wherein said control means controls the cycle of the shutter timing to be shorter than the detected cycle.