JP2001147203A - Substrate inspecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure a sufficiently large high sensitivity detection region without lowering detection sensitivity even if diffracted light and scattered light are intensively generated from a part having a TFT pattern provided thereto. SOLUTION: A laser 10 irradiates the surface of a substrate 20 with laser beam and a photodetector 14 receives the diffracted beam and scattered beam of the laser beam applied to the substrate 20. An integrating circuit 17 integrates the signal corresponding to one line of the photodetector 14 and a conversion table 18 outputs the value related to the intensity of the laser beam emitted from the laser on the basis of the integrated value. A PWN control and oscillation circuit 19 and a drive means 11 drive the laser 10 based on the value related to the intensity of laser beam to control the laser 10 so as to emit laser beam with a predetermined intensity from the laser 10.

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 for detecting whether or not foreign matter is attached to a substrate having a predetermined repetitive pattern, for example, an electrode pattern formed on a glass substrate in a process of manufacturing a liquid crystal display. More particularly, the present invention relates to a substrate inspection apparatus in which control of irradiation intensity of a beam such as a laser during inspection is improved.

[0002]

2. Description of the Related Art A liquid crystal display (LCD: Liqui)
d Crystal Display) is a CRT (C
Since it can be made thinner and lighter than an Anode Ray Tube, a CTV (Color Tele Tube) can be used.
vision) and OA equipment, etc., and the screen size is increased to 10 inches or more.
Higher definition is being promoted. The liquid crystal display has TN (Twisted Nematic)
Type, STN (Super Twisted Neati)
c) type and TFT (Thin Film Trans)
isor) type. TFT-type liquid crystal displays use a TF patterned on each pixel electrode substrate.
T is provided.

[0003] A substrate inspection apparatus detects whether or not a minute foreign substance exists on the pixel electrode substrate. A conventional substrate inspection apparatus irradiates a laser beam from obliquely above a glass substrate on which an electrode pattern is provided, observes scattered light of foreign matter from above, and inspects whether or not foreign matter exists. Conventionally, foreign matter was detected by attenuating the diffracted light using a method such as a spatial filter so that the beam irradiated at the time of inspection would not be diffracted at the electrode pattern part and would not be difficult to distinguish the foreign matter. .

[0004]

However, in a portion where a TFT pattern is present, both diffracted light and scattered light are generated due to the surface shape of the portion, and a sufficient attenuation effect cannot be obtained only with a spatial filter. Was. Therefore, when the detection sensitivity is improved and the beam intensity is increased in order to detect minute foreign matter on the glass substrate, the scattering intensity of the TFT pattern portion increases, thereby saturating the CCD light receiving element, and increasing the intensity. Due to the diffracted light and the scattered light, the inspection area on the glass substrate (pixel area) is reduced, the detection sensitivity is reduced as a whole, and the high-sensitivity detection area is conversely reduced. This will be described below with reference to the drawings.

FIG. 3 is a view schematically showing a positional relationship between a pixel electrode substrate formed on a glass substrate and a CCD light receiving element. FIG. 4 is a diagram showing values of signals output from the CCD light receiving elements in the CCD pixel direction in each positional relationship of FIG. As is clear from FIG. 3, one pixel area is a square area surrounded by TFT driving wirings 31 and 32 provided in the vertical direction and TFT elements and wirings 41 and 42 provided in the horizontal direction. The CCD light receiving element is constituted by a line sensor in which a plurality of pixels are arranged in a horizontal direction. In the drawing, regions 21 to 23 indicate regions detected by the line sensor. When the line sensor is located in the region 21, as shown in FIG. 4A, the beam is scattered by the TFT element and the wiring 41, and the output of the line sensor is saturated. When the line sensor is located in the region 22 near the TFT element and the wiring 41, the influence of the scattered light from the TFT element and the wiring 41 is reduced, and the line sensor is not saturated. On the other hand, when the line-type sensor is located substantially at the center of the pixel area, the influence of the scattered light from the TFT element and the wiring 41 is reduced, and
Only the influence of the scattered light from the driving wires 31 and 32 appears.

When a foreign substance inspection is performed on such a glass substrate, it is necessary to set the laser output to a beam intensity such that the output of the line sensor does not saturate as shown in FIG. However, if the beam intensity is reduced in accordance with the output of the area 21, the detection sensitivity of the pixel area is greatly reduced as shown in FIG. Was.

[0007] The present invention has been made in view of the above-mentioned point, and even when diffraction light and scattered light are strongly generated from a portion provided with a TFT pattern or the like, the detection sensitivity is not reduced. It is an object of the present invention to provide a board inspection apparatus capable of securing a sufficiently large high-sensitivity detection area.

[0008]

According to a first aspect of the present invention, there is provided a substrate inspection apparatus, comprising: an irradiating means for irradiating a light beam onto a substrate surface having a predetermined repetitive pattern; Light receiving element means configured to receive diffracted light and scattered light, and the light beam emitted from the irradiation means based on a signal corresponding to a characteristic portion in a signal output from the light receiving element means Beam intensity converting means for outputting a value relating to the intensity of the light beam; and driving means for driving the irradiating means based on the value relating to the intensity of the light beam output from the beam intensity converting means.

The irradiating means is driven by the driving means,
A light beam having an intensity corresponding to the driving current is emitted to the surface of the substrate to be inspected. The light beam is taken into the light receiving element means as scattered light and diffracted light due to a foreign substance, a TFT pattern, a wiring pattern, or the like existing on the substrate. At this time, the scattered light and the diffracted light due to the TFT pattern and the wiring pattern change periodically according to the pattern shape. For example, when a light beam irradiates a TFT pattern portion, scattered light and diffracted light due to the light beam become strongest,
A large value is output from the light receiving element means. When the light beam irradiates the wiring pattern portion, the scattered light and the diffracted light due to the light beam become minimum, and a small value is output from the light receiving element means. Further, when the light beam irradiates the vicinity of the TFT pattern, the scattered light and the diffracted light due to the light beam have almost the intermediate intensity between the two, and an intermediate value is output from the light receiving element means. Therefore, based on the signal corresponding to the characteristic portion in the signal output from the light receiving element means, which side in the vicinity of the TFT pattern portion, the wiring pattern portion, and the TFT pattern the light beam irradiates is roughly determined. The irradiation position can be specified. Therefore, a value relating to the intensity of the light beam emitted from the irradiating means is obtained based on a signal corresponding to a characteristic portion in a signal output from the light receiving element means using a beam intensity value converting means, and The intensity of the light beam output to the driving means and emitted from the irradiating means is optimized according to the pattern shape on the glass substrate. As a result, even when diffraction light and scattered light are strongly generated from a portion provided with a TFT pattern or the like, a sufficiently large high-sensitivity detection area can be secured without lowering the detection sensitivity.

According to a second aspect of the present invention, in the substrate inspection apparatus according to the first aspect, the beam intensity value converting means outputs a signal for one line or a signal for one line in a signal output from the light receiving element means. , A signal portion corresponding to the repetition pattern is integrated, and a value related to the intensity of the light beam emitted from the irradiation unit is output based on the integrated value. This means that the beam intensity value converting means converts a signal portion corresponding to one line in the signal output from the light receiving element means or a signal portion corresponding to the repetitive pattern in a signal corresponding to one line into a characteristic portion. The integration is limited to output a value related to the intensity of the light beam based on the integration value.

According to a third aspect of the present invention, in the substrate inspection apparatus according to the first aspect, the beam intensity value converting means is equal to or more than a predetermined threshold value in one line signal output from the light receiving element means. And outputs a value related to the intensity of the light beam emitted from the irradiating means based on the integrated value. This means that instead of integrating all the signals for one line, only the signals above a certain threshold are integrated from among them.
On the basis of this, a value related to the intensity of the light beam is limited to be output.

According to a fourth aspect of the present invention, in the substrate inspection apparatus according to the third aspect, the beam intensity value converting means creates a histogram of a signal for one line output from the light receiving element means, and generates the histogram. The predetermined threshold value is determined based on the predetermined threshold value. This limits the threshold value for determining the integration target to be determined based on the histogram.

According to a fifth aspect of the present invention, in the substrate inspection apparatus according to the second, third or fourth aspect, the beam intensity value converting means outputs the signal or the signal for one line in the signal output from the light receiving element means. Integrating means for integrating a signal portion corresponding to the repetitive pattern in a line signal, and a conversion table for converting an integrated value output from the integrating means into a value relating to the intensity of the light beam emitted from the irradiating means And means. This is limited to the case where the beam intensity value converting means is constituted by an integrating means and a conversion table. Therefore, it is needless to say that the beam intensity value conversion means described in claim 1 may be constituted by other calculation means.

According to a sixth aspect of the present invention, in the substrate inspection apparatus according to the fifth aspect, the conversion table means is created based on diffracted light and scattered light of the light beam on the glass substrate detected in advance. It is. This is limited to the case where the conversion table is created based on the scattered light and the diffracted light by irradiating the glass substrate with a light beam in advance, and the conversion table corresponding to various wiring patterns and TFT patterns is created. By doing so, inspection of all glass substrates can be performed smoothly.

According to a seventh aspect of the present invention, in the substrate inspection apparatus according to the first aspect, the beam intensity value converting means outputs a value related to a pulse width in PWM control as a value related to the intensity of the light beam, and the driving means includes A driving current based on the value of the pulse width is supplied to the irradiation unit. This is because the irradiation means is PWM
It is limited to drive by control.

According to a seventh aspect of the present invention, in the substrate inspection apparatus according to the seventh aspect, the driving means includes a bias current close to analog modulation based on a value related to the pulse width, and a current which changes in a pulsed manner to the bias current. Is supplied to the irradiation means. This is limited to the case where the irradiation unit is driven by a drive current in which a bias current and a current on a pulse are superimposed in consideration of the life of the irradiation unit.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a substrate inspection apparatus according to the present invention. The glass substrate 20 is CC
It is configured to automatically move in accordance with the signal capturing timing of the D light receiving element 14. The laser 10 irradiates a laser beam to the glass substrate 20 from obliquely above. The laser drive circuit 11 drives the laser 10 based on a PWM control signal output from the PWM control oscillation circuit 19. Beam position detection sensor 12 for focus adjustment
Receives the laser beam reflected by the glass substrate 20 on the opposite side, and generates a control signal for adjusting the focus and the irradiation position of the laser 10. Here, description of the focus adjustment and the irradiation position adjustment will be omitted.

The detection lens 13 forms an image of the diffracted light and the scattered light from the glass substrate 20 on the CCD light receiving element 14. The CCD light receiving element 14 outputs an electric signal corresponding to the intensity of the beam incident through the detection lens 13 to the amplifier 15.
To the A / D converter 16 via A / D converter 1
6 converts an analog signal from the CCD light receiving element 14 into a digital signal in synchronization with a predetermined clock CLK,
The signal is output to an image processing circuit (not shown) or a one-line integration circuit 17. The one-line integration circuit 17 is a signal for one line of the CCD light-receiving element 14 output from the A / D converter 16 or a characteristic part of the one-line signal, for example, a repetition signal corresponding to a repetition pattern. One or more signals are integrated and the value is output to the conversion table 18. Also, the one-line integration circuit 17 integrates only a signal of a predetermined threshold or more in the one-line signal as a characteristic part from the one-line signal, and converts the value into a conversion table 18. May be output. In order to determine the threshold, a histogram of the signal for one line may be created, and the threshold may be determined based on the histogram. The conversion table 18 converts the integrated value output from the one-line integration circuit 17 into a signal relating to the beam intensity of the laser 10 and outputs the signal to the PWM control oscillation circuit 19.

A laser beam having a constant intensity is applied to the glass substrate 20.
As shown in FIG. 4, the output level from the CCD light-receiving element 14, that is, the integrated value differs according to the irradiation position (regions 21 to 23). Thus, it is possible to specify which position on the glass substrate 20 the laser beam is irradiating based on the integrated value. That is, since the integrated value and the irradiation position are in a corresponding relationship, the substrate inspection apparatus controls the laser 10 so that the laser beam is emitted at a beam intensity such that the CCD light receiving element 14 is not saturated at the irradiation position. I have.

That is, the PWM control oscillation circuit 19 outputs a PWM control signal (a signal whose pulse width is controlled) to the laser drive circuit 11 based on the signal regarding the beam intensity output from the conversion table 18. The laser drive circuit 11 drives the laser 10 based on the PWM control signal. The laser drive circuit 11 supplies the laser 10 with a bias current close to analog modulation and a drive current in which a pulse-like drive current is superimposed on the bias current in consideration of the life of the laser 10.

FIG. 2 shows the positional relationships (regions 21 to 2) of FIG.
FIG. 3C is a diagram illustrating a value in the pixel direction of a signal output from the CCD light receiving element 14 in 3), and corresponds to FIG. 4. When the CCD light receiving element 14 is located in the area 21, a saturated signal as shown in FIG. 4A is output, and the beam intensity at this position must be reduced.

In this embodiment, when a value corresponding to the integral value of the saturation signal as shown in FIG. 4A is detected, the conversion table 18 changes the value to decrease the beam intensity by the PWM control oscillation. Since the light is output to the circuit 19, the beam intensity of the laser 10 is reduced, and
From this, a signal without saturation as shown in FIG. 2A is output. Next, the CCD light receiving element 14 is
, A signal as shown in FIG. 4B is output. Since the beam intensity at this position is appropriate, the value as it is is used. On the other hand, when the CCD light receiving element 14 is located in the area 23, a relatively small signal as shown in FIG. 4C is output, so that the beam intensity at this position must be increased.

In this embodiment, when a relatively small detection signal as shown in FIG. 4C is detected, the conversion table 18 outputs a value for increasing the beam intensity to the PWM control oscillation circuit 19. Laser 10
Is increased, and a relatively high-sensitivity detection signal as shown in FIG. 2C is output from the CCD light receiving element 14. It should be noted that the conversion table 18 is prepared so that diffraction light and scattered light of a light beam on the glass substrate 20 are detected in advance, and an optimum output signal is obtained based on the detected value. by this,
An optimum beam can be irradiated according to various pattern configurations of the glass substrate 20.

In the above-described embodiment, the case where the laser beam intensity is controlled by PWM control has been described. However, it is needless to say that the laser beam intensity may be controlled by other methods. Further, in the above-described embodiment, the one-line integration circuit 18 outputs C
The case where the output of the CD light receiving element 14 is integrated and the value of the conversion table is determined based on the integration has been described.
The PWM control oscillation circuit 19 may be controlled so that the output of the D light receiving element 14 does not become larger than a predetermined value, that is, so as not to be saturated. Alternatively, the case where the output of the CCD light receiving element 14 is saturated may be detected, and the laser beam intensity may be reduced to a value that does not saturate. In this case, instead of the one-line integration circuit 18, a histogram may be created based on the output of the CCD light receiving element 14, and the laser beam intensity may be controlled based on the histogram.

In the above embodiment, the irradiation means is described as a laser. However, the irradiation means is not limited to a laser, but may be white light such as a xenon lamp. Further, the present invention provides a mask having a predetermined repeating pattern other than a glass substrate,
It goes without saying that the present invention can be applied to a reticle, a wafer, and the like.

[0026]

According to the present invention, even when diffraction light and scattered light are strongly generated from a portion provided with a TFT pattern or the like, a sufficiently large high-sensitivity detection can be performed without lowering the detection sensitivity. There is an effect that an area can be secured.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a glass substrate inspection system of the present invention.

FIG. 2 is a diagram illustrating a C of a signal output from a CCD light receiving element in each of the positional relationships shown in FIG.
FIG. 4 is a diagram illustrating values in a CD pixel direction.

FIG. 3 shows a pixel electrode substrate formed on a glass substrate and C
It is a figure which shows the outline of the positional relationship with a CD light receiving element.

FIG. 4 is a diagram showing values of signals output from a CCD light receiving element in a conventional glass substrate inspection system in a CCD pixel direction in each positional relationship of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Laser 11 ... Laser drive circuit 12 ... Beam position detection sensor 13 ... Detection lens 14 ... CCD light receiving element 15 ... Amplifier 16 ... A / D converter 17 ... One line integration circuit 18 ... Conversion table 19 ... PWM control oscillation circuit 20 ... Glass substrate 31, 32 ... TFT drive wiring part 41,42 ... TFT element part and wiring part

Claims (8)

[Claims] An irradiating means for irradiating a substrate surface having a predetermined repetitive pattern with a light beam; and a light receiving element means configured to receive diffracted light and scattered light of the light beam irradiated on the substrate. Beam intensity value converting means for outputting a value relating to the intensity of the light beam emitted from the irradiating means based on a signal corresponding to a characteristic portion in a signal output from the light receiving element means; A substrate inspection apparatus comprising: a driving unit that drives the irradiation unit based on a value related to the intensity of the light beam output from the intensity value conversion unit. 2. The signal part according to claim 1, wherein the beam intensity value converting means includes a signal for one line in the signal output from the light receiving element means or a signal portion corresponding to the repetitive pattern in the signal for one line. And outputting a value related to the intensity of the light beam emitted from the irradiation means based on the integrated value. 3. The beam intensity conversion means according to claim 1, wherein the beam intensity value conversion means integrates only a signal having a predetermined threshold value or more among signals of one line output from the light receiving element means, and the integrated value is obtained. A substrate inspection apparatus for outputting a value relating to the intensity of the light beam emitted from the irradiating means on the basis of the following. 4. The apparatus according to claim 3, wherein the beam intensity value conversion means creates a histogram of the signal for one line output from the light receiving element means, and determines the predetermined threshold value based on the histogram. A substrate inspection apparatus. 5. The signal according to claim 2, 3 or 4, wherein the beam intensity value converting means converts the signal for one line in the signal output from the light receiving element means or the repetitive pattern in the signal for one line. Integrating means for integrating a corresponding signal portion; and conversion table means for converting an integrated value output from the integrating means into a value relating to the intensity of the light beam emitted from the irradiating means. Substrate inspection equipment. 6. The substrate inspection apparatus according to claim 5, wherein the conversion table means is created based on diffraction light and scattered light of the light beam on the glass substrate detected in advance. . 7. The apparatus according to claim 1, wherein the beam intensity value conversion unit outputs a value related to a pulse width in PWM control as a value related to the intensity of the light beam, and the driving unit drives based on a value related to the pulse width. A substrate inspection apparatus configured to supply a current to the irradiation unit. 8. The irradiation device according to claim 7, wherein the driving unit irradiates a bias current close to analog modulation based on the value related to the pulse width, and a drive current obtained by superimposing a pulse-like current on the bias current. A substrate inspection apparatus characterized in that it is supplied to a means.