JPH09320939A - Position detection method and device - Google Patents

Abstract

(57) Abstract: A position detection method and device for irradiating an alignment mark formed on a glass substrate with visible light and detecting reflected light reflected by the alignment mark by a detection device to obtain position information. Provided is a position detection method and device capable of performing accurate position detection, by which easy detection and good reflected light can be obtained even when a film is further formed on the alignment mark on the glass substrate. To do. SOLUTION: An alignment mark formed on a glass substrate is irradiated with light, light passing through the glass substrate after reaching the alignment mark is detected, and the position of the glass substrate is obtained based on the detected light. And

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting the position of an apparatus which requires alignment, and more particularly, to a method for detecting the position of a glass substrate after forming a layer of an opaque substance such as metal on the glass substrate. The present invention relates to a position detection method and device in an exposure device that aligns and performs exposure, a defect inspection device that performs defect inspection, or a microscope that performs observation.

[0002]

2. Description of the Related Art When performing a defect inspection of a liquid crystal substrate with a defect inspection apparatus or observing the liquid crystal substrate with an observation microscope, it is necessary to position the liquid crystal substrate to be the defect inspection or the observation target. There is. Further, in the exposure apparatus, when an opaque layer such as a metal is formed on the glass substrate in the exposure process, when the layer before the layer and the pattern of the reticle to be transferred on the layer are superposed, It is necessary to position the board. Positioning in a conventional exposure apparatus for producing a liquid crystal display element has been performed by the method and apparatus shown in FIG.

In FIG. 1, an exposure apparatus 1 comprises a projection optical system PL, a reticle R as a mask, and an illumination optical system IL including a light source. The glass substrate 2 to be positioned is placed on the stage 3 via a vacuum suction means (not shown). The stage 3 can be moved in the left-right direction in the drawing by a motor 4. Also, stage 3
Can also be moved in the direction perpendicular to the drawing by a motor (not shown). An alignment mark 5 is formed on the glass substrate 2 simultaneously with an electronic circuit (not shown). The alignment mark 5 is made of metal such as chrome. As the alignment sensor 6,
A system that irradiates the alignment mark 5 on the glass substrate with laser light, relatively moves the laser light and the alignment mark, and measures the position of the alignment mark using the light diffracted and scattered from the mark (hereinafter, Laser
Step Alignment It is called "LSA". ). Such an LSA alignment system is disclosed in JP-A-60-13.
No. 0742 is disclosed in detail. The light emitted from the light source 7 reaches the alignment mark 5 through the condenser lens 8 and the light-sending slit 9. The light source 7 is a visible light (wavelength 3
80 to 780 nm), for example, a He-Ne laser (wavelength 633 nm) is used. The reflected light reflected by the alignment mark 5 passes through the relay lens 10, is polarized by the polarizing prism 11, and enters the detector 12. The detector 12 measures the position of the alignment mark 5.
The position information of the alignment mark 5 is sent to the control system 13. The control system 13 calculates the deviation amount from the position information, and based on the deviation amount, the position reader 14 such as a light wave interferometer or a linear encoder is used to move the stage 3 by the motor 4 to move the glass substrate. Position two.

As described above, in the conventional apparatus, the laser beam is irradiated from the upper surface of the glass substrate, that is, the surface on which the alignment mark is arranged, and the reflected light reflected on the same side is detected to detect the position of the glass substrate. Was measured and positioned. That is, the position of the alignment mark is detected by epi-illumination.

[0005]

As described above, in the exposure process for producing a liquid crystal display element, a fine electronic circuit is first formed on the glass substrate 2 at the same time as the alignment mark 5 as shown in FIG. 2, for example. Form. The electronic circuit and the alignment mark of the first layer are made of an opaque substance such as metal. Furthermore, the semiconductor film 15 and the resist 16 for the second and subsequent layers are formed on the first layer.
Is generally formed. Therefore, it is difficult to detect the alignment mark formed of the metal of the first layer by the conventional epi-illumination in order to position the glass substrate in the exposure and the defect inspection of the second and subsequent layers. However, there is a problem that the positioning accuracy is significantly reduced. In order to solve this problem, it is possible to adopt a method in which the alignment marks are replaced and a new alignment mark is used for positioning, but this method has a problem in that it is complicated.

In the exposure process for producing the liquid crystal display element, there are the following problems. The color filter of the liquid crystal display element includes a red (R) filter, a green (G) filter and a blue (B) filter.
These color filters are formed by applying color resists of the respective colors on an electronic circuit pattern formed of a metal film or a transparent conductive film (ITO film) on a glass substrate,
It may be produced through an exposure process. In this case, the alignment mark formed at the same time as the electronic circuit pattern is also made of the above metal film or transparent conductive film. The color resist has a remarkably lower transmittance for visible light than a normal resist, and in particular, the blue color resist has a transmittance for visible light of about 1%. For example, when this blue color resist is applied on the alignment mark, visible light is emitted from the upper surface of the glass substrate, that is, the surface on which the alignment mark is arranged, and the reflected light reflected on the same side is detected. In the conventional method, the light intensity of the reflected light is 0.01 × 0.01 times the light intensity of the irradiation light,
That is, it becomes about 0.01%, which makes it difficult to detect reflected light.

The present invention has been made in view of the above conventional problems, and irradiates an alignment mark formed on a glass substrate with visible light, and a reflected light reflected by the alignment mark is detected by a detection device. In the position detection method of obtaining the position information by detecting, even if a film is further formed on the alignment mark on the glass substrate, it is easy to detect and good detection light (reflected light, transmitted light, diffracted light, scattered light) Etc.) is obtained, and thereby a position detection method capable of performing accurate position detection is provided.

Further, according to the present invention, even when an opaque film such as a metal film is formed on the alignment mark formed on the first layer on the glass substrate, reflected light that can be easily detected is obtained. An object of the present invention is to provide a position detection method and a position detection device that can perform accurate position detection.

Further, according to the present invention, even when a color resist having a transmittance for visible light which is significantly lower than that of a normal resist is applied on the alignment mark formed on the first layer on the glass substrate. An object of the present invention is to provide a position detection method and a position detection device which can obtain reflected light or transmitted light that can be easily detected and can perform accurate position detection.

[0010]

In order to solve the above problems, the present invention irradiates a pattern formed on a test object with light and, after reaching the pattern, passes through the test object. Is detected, and the position of the test object is obtained based on the detected light.

In the present invention, the pattern formed on the test object is irradiated with light, and the light passing through the test object after reaching the pattern is detected. Therefore, the light diffracted and scattered by the pattern is detected. Can be easily detected through a test object, and accurate position detection can be performed. Further, because of the above-mentioned configuration, in the conventional method, in order to detect the light diffracted / scattered by the pattern through the metal layer or the color resist layer formed on the pattern, not through the test object. The problem that light is absorbed by these metal layers and color resist layers and detection becomes difficult can be solved.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a position detecting method for detecting the position of an object to be inspected, which comprises an irradiation step of irradiating a pattern formed on the object to be inspected with light, and an object to be inspected after reaching the pattern. The method includes a step of detecting light passing through the inspection object, and a step of obtaining the position of the inspection object based on the detected light.

In the irradiation step, light may be applied to the pattern through the test object. That is, the irradiation may be performed from the back side of the test object on which the pattern is formed.

Further, the present invention is a position detecting device for detecting the position of an object to be inspected, comprising: an irradiation optical system for irradiating a pattern formed on the object to be inspected with light; It is a position detecting device including a detector that detects light that passes through an object and a computer that determines the position of an object to be inspected based on the detected light.

The illuminating optical system may be arranged so as to illuminate the pattern through the test object. That is, it is preferable that the pattern is formed so as to be irradiated from the back side of the test object.

The test object may be a transparent substrate. The transparent substrate is preferably a glass substrate. Further, the pattern may be an alignment mark for alignment.

Furthermore, the present invention is a positioning method for positioning a stage, which comprises a step of disposing a transparent substrate on the stage, a step of forming an alignment mark on the transparent substrate, and a step of applying light to the alignment mark. An irradiation step of irradiating, a step of detecting light passing through the transparent substrate after reaching the alignment mark, and based on the detected light,
It is a positioning method including a step of obtaining position information of the transparent substrate and a step of moving the stage to position the stage based on the position information.

In the irradiation step, light may be applied to the pattern through the test object. That is, the irradiation may be performed from the back side of the test object on which the pattern is formed.

A step of applying a substance having a high light reflectance or a substance having a low light transmittance may be included on the alignment mark.

Furthermore, the present invention is a positioning device for positioning a stage, which comprises an irradiation optical system for irradiating an alignment mark formed on a transparent substrate arranged on the stage with light, and an alignment optical system. A detector that detects light that has passed through the transparent substrate after it has arrived, a calculator that calculates the amount of positional deviation of the transparent substrate based on the detected light, and a stage that moves to position the stage based on the amount of positional deviation. The positioning device comprises a driving device.

The stage has an opening at a position corresponding to the alignment mark, the irradiation optical system is arranged on the side of the transparent substrate opposite to the side where the alignment mark is formed, and It is configured to irradiate the alignment mark with light through the opening, and the detector is arranged on the side of the transparent substrate opposite to the side where the alignment mark is formed and is reflected by the alignment mark. Light emitted from the irradiation optical system may be detected through the transparent substrate and the opening of the stage.

The stage has an opening at a position corresponding to the alignment mark, the irradiation optical system is arranged on the side of the transparent substrate on which the alignment mark is formed, and the detector is the alignment on the transparent substrate. It is arranged on the side opposite to the side where the mark is formed, and is configured to detect the light from the irradiation optical system diffracted and scattered by the alignment mark through the transparent substrate and the opening of the stage. May be.

A substance having a high light reflectance or a substance having a low light transmittance may be coated on the alignment mark.

The positioning device may be provided in the exposure device.

According to the present invention configured as described above,
Even if a film is further formed on the pattern formed on the upper surface of the test object, after irradiating light from the back surface side of the test object and reaching the pattern through the test object and being reflected by the pattern The position of the test object can be detected by detecting the light passing through the test object again and photoelectrically converting the detected light. Further, according to the present invention, when a film having a low light transmittance is formed on the pattern of the test object, the light is reflected by the pattern even when the light is radiated from the upper surface of the test object. Since it is possible to detect the transmitted light that passes through the test object instead of the light that passes through the low-transmittance film again, the light diffracted and scattered by the pattern can be detected without passing through the low-transmittance film. Accurate position detection can be performed.

According to the present invention, in a liquid crystal substrate exposure process in which one substrate is exposed at least twice or more,
The position of the glass substrate when aligning the original plate and the glass substrate that have alignment marks for alignment with each other in the exposure device, or in the device for inspecting and observing the glass substrate already created including the alignment mark When performing the alignment, the light source and the light receiving element that can detect the reflected light from the glass substrate of the light emitted from the light source are arranged on the surface of the glass substrate that does not include the alignment mark, that is, on the back surface side. It can detect various positions.

In the present invention, if the test object is a liquid crystal substrate, the substrate is glass. Glass is usually
High transmittance for visible light. Further, when forming the metal layer on the liquid crystal substrate, the material thereof is chromium or aluminum, and these metals have high reflectance with respect to the laser light. Further, the resist used during exposure has a characteristic of high transmittance and low reflectance. Therefore, for example, when a pattern of a metal film is formed on a normal glass substrate, a metal film is further formed on which layer on the surface, and a resist is further applied on the metal film, position detection is performed. By irradiating from the back surface of the substrate as a method of irradiating from the light source and detecting the reflected light, it is difficult or impossible to detect the pattern position on the glass substrate by the method of reflecting or transmitting from the front surface of the substrate. Disappears.

[0028]

FIG. 3 is a diagram showing a first embodiment according to the present invention. In FIG. 3, the exposure device 21 includes a projection optical system PL.
And a reticle R as a mask and an illumination optical system IL including a light source. The liquid crystal board to be positioned is
It consists of a glass substrate 22. The glass substrate 22 is placed on the stage 23 via a vacuum suction means (not shown). The stage 23 can be moved in the left-right direction in the drawing by a motor 24. The stage 23 can also be moved in the direction perpendicular to the drawing by a motor (not shown). An alignment mark 25 is formed as a first layer on the glass substrate 22 with a metal film. The alignment mark 25 is formed simultaneously with an electronic circuit (not shown). The semiconductor film 26 and the resist 27 for the second exposure process are vapor-deposited and applied on the alignment mark 25 of the first layer to form the second layer.

When such a liquid crystal substrate is used to detect reflected light by epi-illuminating light from the upper surface side of the liquid crystal substrate by the conventional position detecting device shown in FIG.
Also, since the reflected light must be detected through the semiconductor film 26, the contrast of the alignment mark 25 is lowered and the position detection becomes difficult. Further, when the third layer is applied, position detection becomes more difficult than the position detection in the second layer.

Therefore, the first embodiment of the present invention is to irradiate light (beam) from the back side of the liquid crystal substrate. LSA is used as the alignment sensor 28 of the first embodiment. The light emitted from the light source 29 passes through the condenser lens 30 and the light transmission slit 31, and passes through the stage 2
3 through the opening 23a provided in the glass substrate 22
To reach the alignment mark 25. Here, in the opening 23a provided in the stage 23, at least a portion at a position corresponding to the alignment mark 25 may be hollow. The light source 29 uses visible light (wavelength 380 to 780 nm), for example, a He-Ne laser (wavelength 633 nm). The reflected light reflected by the alignment mark 25 again passes through the glass substrate 22 and the relay lens 32, is polarized by the polarization prism 33, and enters the detector 34. The detector 34 measures the position of the alignment mark 25 and generates position information. The position information of the alignment mark 25 is stored in the control system 35.
Sent to The control system 35 calculates a shift amount from the position information, and based on the shift amount, a position reader 36 such as a light wave interferometer or a linear encoder is used to drive the motor 24.
Thus, the stage 23 is moved to position the glass substrate 22.

The important point here is the alignment mark 2
Even if the material coated on the substrate 5 is not the semiconductor film 26 but the color resist for the color filter, the position can be similarly detected by the method shown in the first embodiment. .

FIG. 4 is a diagram showing a second embodiment according to the present invention. 4, the same components as those of the first embodiment shown in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted. Second
In the embodiment, the light source is arranged on the upper surface side of the liquid crystal substrate and the detector is arranged on the lower surface side of the liquid crystal substrate to detect the transmitted light. In the second embodiment, it is assumed that the color resist 41 is applied on the alignment mark 25 of the first layer. The light source 42 is arranged on the upper surface of the glass substrate 22, that is, on the side on which the alignment mark 25 is provided. The light emitted from the light source 42 is
The light enters the color resist 41 through the condenser lens 43 and the light-sending slit 44. The light passes through the color resist 41 and reaches the alignment mark 25. The color resist 41 has a low light transmittance, and for example, a blue color resist has a light transmittance of about 1%. Therefore, since the reflected light from the alignment mark 25 is about 0.01% of the incident light, if the reflected light is detected as in the conventional technique, the detection accuracy is lowered. On the other hand, the second embodiment is intended to detect the light diffracted / scattered by the alignment mark 25 via the glass substrate 22. That is, the light diffracted and scattered by the alignment mark 25 passes through the glass substrate 22 and passes through the stage 2
3 through the opening 23a provided to the relay lens 45 provided on the lower surface side of the glass substrate. The light that has passed through the relay lens 45 is polarized by the polarization prism 46 and enters the detector 47. The detector 47 measures the position of the alignment mark 25 and generates position information.
The position information of the alignment mark 25 is sent to the control system 35. The control system 35 positions the glass substrate 22 as in the first embodiment.

FIG. 5 is a diagram showing a third embodiment according to the present invention. 5, the same components as those of the first embodiment shown in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted. Third
The embodiment has a function of irradiating light from the upper surface side of the glass substrate and detecting reflected light to the upper surface side, and a function of irradiating light from the lower surface side of the glass substrate to reflect light to the lower surface side. It has both of the functions of detecting and the function of detecting, and these methods can be switched according to the object to be inspected.

In FIG. 5, when performing alignment for the exposure of the second layer using the alignment mark 25 of the first layer formed of a metal film, it is arranged on the upper surface side of the glass substrate 22. The light source 51 is used. The light emitted from the light source 51 passes through the condenser lens 52 and the light sending slit 53 to reach the alignment mark 25. The reflected light reflected by the alignment mark 25 passes through the relay lens 54, is polarized by the polarization prism 55, and is detected by the detector 5
It is incident on 6. The detector 56 uses the alignment mark 25.
The position information is generated by measuring the position of. The position information of the alignment mark 25 is sent to the control system 35. The control system 35 positions the glass substrate 22 as in the first embodiment.

Next, at the time of alignment for the exposure of the third layer, if the same method as that of the second layer is difficult, the light source 51 is moved to the glass substrate 2 by the changeover switch 57.
By switching to the light source 29 arranged on the lower surface side of No. 2, the alignment mark 25 is irradiated with light from the lower surface side of the glass substrate 22 as in the first embodiment. The reflected light from the alignment mark 25 is applied to the relay lens 3
2. It can be detected by the detector 34 via the polarization prism 33.

The same method as described above can be applied to the fourth and subsequent layers. After detecting the reflected light for alignment in this way, accurate positioning is performed using the position reader 36 such as a light wave interferometer or a linear encoder.

In the third embodiment described above, the alignment mark 25 is irradiated by the light source 51 arranged on the upper surface side of the glass substrate, and the transmitted light transmitted through the glass substrate 22 is detected through the polarization prism 33. A mechanism for detecting with the device 34 may also be used. Even in this case, it is preferable that the mechanism can be switched by the changeover switch 57.

In the above embodiment, the alignment mark 2
Although the light radiated to 5 is described on the premise that visible light is used, the present invention is not limited to visible light, and for example, a transparent conductive film (ITO) may be used.
The same can be applied to the case of using light having another wavelength such as infrared rays having a high reflectance for the film).

[0039]

The present invention is embodied in the form described above and has the following effects.

According to the present invention, since the alignment mark for aligning the glass substrate can be always detected with high contrast, it is possible to perform highly accurate alignment. Further, since there is an alignment mark that can always perform highly accurate alignment, it is not necessary to change the alignment mark for alignment in the third and subsequent layers, which simplifies the design of the original plate. There is also an effect that the processing time can be shortened.

Furthermore, the present invention can be applied not only to a liquid crystal substrate but also to an exposure process or an inspection process for a glass substrate coated with a photosensitive material having a low visible light transmittance such as a color filter.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a conventional alignment device.

FIG. 2 is a cross-sectional view when an alignment mark is formed on a glass substrate as a test object to be aligned, and a second layer is formed thereon and a resist is applied.

FIG. 3 is a diagram showing a first embodiment according to the present invention.

FIG. 4 is a diagram showing a second embodiment according to the present invention.

FIG. 5 is a diagram showing a third embodiment according to the present invention.

[Explanation of symbols]

 29, 42, 51 Light source 30, 43, 52 Condensing lens 31, 44, 53 Light-sending slit 32, 45, 54 Relay lens 33, 46, 55 Polarizing prism 34, 47, 56 Detector (photoelectric conversion element) 22 Glass Substrate 23 Stage 36 Position Reader 25 Alignment Mark 26 Semiconductor Film 27 Resist 41 Color Resist

Claims (18)

[Claims] 1. A position detecting method for detecting the position of an object to be inspected, comprising: an irradiation step of irradiating a pattern formed on the object to be inspected with light; A position detecting method comprising: a step of detecting light passing therethrough; and a step of obtaining the position of the test object based on the detected light. 2. The irradiation step irradiates the pattern with light through the test object.
The method described in. 3. The method according to claim 1, wherein the test object is a transparent substrate. 4. The method according to claim 1, wherein the pattern is an alignment mark. 5. A position detecting device for detecting the position of an object to be inspected, comprising: an irradiation optical system for irradiating light onto a pattern formed on the object to be inspected; and the object to be inspected after reaching the pattern. A position detecting device comprising a detector for detecting light passing through and a calculator for obtaining the position of the object to be measured based on the detected light. 6. The apparatus according to claim 5, wherein the irradiation optical system irradiates the pattern with light through the test object. 7. The apparatus according to claim 5, wherein the test object is a transparent substrate. 8. The apparatus according to claim 5, wherein the pattern is an alignment mark. 9. A positioning method for positioning a stage, comprising: disposing a transparent substrate on the stage; forming an alignment mark on the transparent substrate; and irradiating the alignment mark with light. A step of detecting light passing through the transparent substrate after reaching the alignment mark, a step of obtaining positional information of the transparent substrate based on the detected light, and a stage of the stage based on the positional information. And moving the stage to position the stage. 10. The method according to claim 9, wherein the irradiation step irradiates the alignment mark with light through the transparent substrate. 11. The method according to claim 9, further comprising the step of applying a substance having a high light reflectance onto the alignment mark. 12. The method according to claim 9, further comprising the step of applying a substance having a low light transmittance onto the alignment mark. 13. A positioning device for positioning a stage, comprising: an irradiation optical system for irradiating an alignment mark formed on a transparent substrate arranged on the stage with light; A detector for detecting light passing through the transparent substrate, a calculator for obtaining the amount of positional deviation of the transparent substrate based on the detected light, and the stage for positioning the stage based on the amount of positional deviation Positioning device comprising a drive device for moving the. 14. The stage has an opening at a position corresponding to the alignment mark, and the irradiation optical system is provided on a side of the transparent substrate opposite to a side where the alignment mark is formed. Is arranged and configured to irradiate the alignment mark with light through the opening of the stage, wherein the detector is a side on which the alignment mark on the transparent substrate is formed. Is arranged on the side opposite to the side, and is configured to detect the light from the irradiation optical system reflected by the alignment mark through the transparent substrate and the opening of the stage. 14. The apparatus of claim 13 characterized. 15. The stage has an opening at a position corresponding to the alignment mark, and the irradiation optical system is arranged on a side of the transparent substrate where the alignment mark is formed. The detector is disposed on the side opposite to the side where the alignment mark is formed on the transparent substrate, and the light from the irradiation optical system diffracted / scattered by the alignment mark 14. The apparatus according to claim 13, wherein the apparatus is configured to detect through the transparent substrate and the opening of the stage. 16. The apparatus according to claim 13, wherein the alignment mark is coated with a substance having a high light reflectance. 17. The apparatus according to claim 13, wherein the alignment mark is coated with a substance having a low light transmittance. 18. An exposure apparatus having the positioning device according to claim 13.