JPH08292580A - Exposure equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to detect the position of an alignment mark under a resist without exposing the resist on an object to be exposed by illumination light in which two lights having different wavelengths are mixed. Constitution: Position detection means 21 to 27, which are formed of a thin film and detect the position of the object to be exposed based on light from an alignment mark provided on the object to be exposed 1, and two illuminations having different wavelengths. Illuminating means for mixing light and irradiating the mark, wherein the wavelength of each light is set so that the intensity of the mixed illuminating light reflected from the mark is averaged with respect to the change in the film thickness of the mark. In an exposure apparatus including 4 to 20, which aligns an object to be exposed for exposure based on the detection result of the position detection means, the resist applied to the object to be exposed and the mark is not exposed to the mixed illumination light. The control means 15, 28, 29 for controlling the irradiation time of at least one of the illumination light components is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus used for manufacturing a liquid crystal panel or the like.

[0002]

2. Description of the Related Art In general, a display panel to which a liquid crystal panel is applied is applied in a wide range of fields from a relatively small one such as a calculator and a clock to a large display for an automobile and a display such as a personal computer and a word processor. Has been done.

In the manufacturing process of such a liquid crystal panel, there is an exposure process for forming a transparent electrode, and in that process, the transparent electrode pattern of the liquid crystal panel and the pattern of the previous process are accurately aligned and exposed. There is a need to.
By the way, in general, an ITO film is often used as the transparent electrode material, and at the same time, the mark used for alignment is also formed from the same material in terms of production process and cost.
However, the transparent electrode thin film used for the liquid crystal panel is
The film is formed with a thickness of 50,000 Å or less, and it has the highest sensitivity to the human eye (54
In many cases, the thickness of the transparent electrode is about 0 nm (near 0 nm), and the image of the transparent electrode has a remarkably low contrast, and there is a problem that it is difficult to visually observe or observe with a TV camera.

In response to such a problem, in the case of simultaneously irradiating ultraviolet light and near infrared light having a relatively high reflectance, I
An observation illumination means has been proposed which is capable of obtaining a stable contrast with respect to the change in the film thickness of the TO electrode.

[0005]

However, according to this prior art, as a light source for observing an alignment mark formed of an ITO thin film (hereinafter referred to as an ITO mark), ultraviolet light having a wavelength of around 400 nm and 630 are used. [Nm]
Although near-infrared light is used in the vicinity, when this light source is used in an exposure apparatus, there arises a problem that the resist is exposed to ultraviolet light in the vicinity of 400 [nm].

An object of the present invention is to enable detection of the position of an alignment mark under the resist without exposing the resist on the object to be exposed with illumination light that is a mixture of two lights having different wavelengths. .

[0007]

In view of the above problems, the present invention determines the position of an exposed object based on light from an alignment mark formed of a thin film and provided on the exposed object. Position detecting means for detecting and different wavelength 2
This is an illuminating device that mixes two illumination lights and irradiates the mark, and the wavelength of each light is set so that the intensity of the mixed illumination light reflected from the marks is averaged with respect to the change in the thickness of the mark. In an exposure apparatus that includes an object for aligning an exposed object for exposure based on the detection result of the position detection means, at least the resist applied on the exposed object and the mark is not exposed to the mixed illumination light. It is characterized by comprising a control means for controlling the irradiation time of one of the illumination light components.

Further, the control means is characterized in that it comprises a blocking means for blocking the illumination light on the optical axis of the illumination means.

Further, the detecting means is characterized in that the image of the mark is taken into the memory in synchronization with the opening of the blocking means, and the position detecting process is executed on the image taken into the memory.

[0010]

[Function] The exposure of the resist is prevented by the illumination light, and the image of the ITO mark can be obtained with a good contrast by the mixed illumination light according to the film thickness of the resist on the object to be exposed, and the detection range can be made very large. It becomes possible to widen.

[0011]

1 is a schematic view of a projection type exposure apparatus according to an embodiment of the present invention. In the figure, reference numeral 20 denotes a white light source such as a halogen lamp or a xenon lamp, and the light flux emitted from this light source passes through or is reflected by the half mirror 18. The light reflected by the half mirror 18 is reflected by the half mirror 19 and is reflected by the band pass filter 17 by 63.
It becomes near-infrared monochromatic light near 0 [nm].

The light passing through the half mirror 18 is
By the bandpass filter 16, it becomes a monochromatic light of ultraviolet light around 400 [nm]. A liquid crystal shutter 15 is provided in the optical path of the ultraviolet light, and the irradiation time of the ultraviolet light is adjusted by opening and closing the liquid crystal shutter.

Reference numerals 11 and 12 denote ND filters arranged on the optical paths of ultraviolet light and near infrared light, and 13 and 14 denote stepping motors for rotating the ND filters 11 and 12, respectively, which are suitable for the stepping motors 13 and 14. By applying a pulse, it is possible to arbitrarily change the illumination light amounts of ultraviolet light and near infrared light.

Reference numerals 9 and 10 denote bifurcated light guides for guiding the ultraviolet light and the near infrared light from the ND filters 11 and 12 to two observation systems of a right system and a left system, respectively.

In the present embodiment, the alignment optical systems of the left and right observation systems are symmetrical, so the right alignment optical system will be described below.

Near-infrared light of the light flux divided by the bifurcated light guides 11 and 12 is a lens 7 and a half mirror 6.
And is reflected by the half mirror 5. The ultraviolet light passes through the lens 8 and is reflected by the half mirrors 6 and 5.

After that, the light flux reflected by the half mirror 5 illuminates the surface of the mask 3 by the objective lens 4 and the surface of the glass plate 1 which is the conjugate surface of the projection optical system 2 and is reflected.

The light reflected by the surface of the glass plate 1 passes through the objective lens 4, the half mirror 5 and the beam splitter 21, and then is guided to the image pickup surface of the TV camera 25 through the roof prism 22, the lenses 23 and 24. .

Next, ultraviolet light irradiation time control means and ITO
The mark position detecting means will be described.

In FIG. 1, reference numeral 28 denotes a microprocessor. When the ITO mark position is detected, the microprocessor 28 outputs a command to the liquid crystal shutter drive circuit 29 to open the shutter 15. Upon receiving the instruction, the liquid crystal shutter drive circuit 29 opens the liquid crystal shutter 15 in the ultraviolet light optical path. Further, the microprocessor 28 issues an image processing start command to the image processing unit 27 in synchronization with the liquid crystal shutter open command. In response to this, the image processing unit 27 stores the image obtained from the TV camera 25 through the video amplifier 26 in the memory,
Position detection processing is performed on the image on the memory.

Further, when a preset time has elapsed, the microprocessor 28 outputs a command to the liquid crystal shutter drive circuit 29 to close the shutter, and closes the liquid crystal shutter 15.

Here, if the opening time of the shutter 15 is set so that the integrated exposure amount on the glass substrate 1 provided with the resist is equal to or less than the photosensitivity of the resist,
It is possible to observe the image of the ITO mark by mixing illumination light of two wavelengths of ultraviolet and near infrared without exposing the resist. For example, a general resist has an illuminance of 20.
With a general exposure light source of about 00 [mw], the exposure time is 0.05 to 0.3 seconds. On the other hand, since the illuminance of the light source 20 for observation is from several mW to at most 10 mW, it takes 10 to 60 seconds to expose the resist. Therefore, in order to prevent the resist from being exposed by the light source 20, a time sufficiently shorter than the above-mentioned exposure time, that is, an observation illumination time of about 0.1 to 1 second is set,
The liquid crystal shutter may be controlled.

FIG. 2 shows the case of 640 [nm] near infrared light and 41
It is a figure showing the relationship between a resist film thickness and reflectance when a resist is irradiated with ultraviolet light of 0 [nm]. From this figure, it is possible to widen the detection range of the alignment mark by mixing and using the illumination light of these two wavelengths according to the film thickness of the resist on the glass substrate 1.

[0024]

As described above, according to the present invention,
Since the resist applied to the object to be exposed and the mark is not exposed to the mixed illumination light, a control means for controlling the irradiation time of at least one of the illumination light components is provided, so that the resist is exposed to the illumination light. This makes it possible to obtain an image of the ITO mark with good contrast by the mixed illumination light according to the film thickness of the resist on the object to be exposed, and to make the detection range extremely wide.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a projection type exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between resist film thickness and reflectance according to an example of the present invention.

[Explanation of symbols showing main parts of the drawing]

1: glass plate, 2: projection optical system, 3: mask,
4: Objective lens, 5, 5 ', 6, 6', 18, 18 ',
19, 19 ': Half mirror, 7, 7', 8, 8 ', 2
3,24: Lens, 9,10: Bifurcated light guide, 1
1, 12: stepless rotary ND filter, 13, 14: stepping motor, 15: liquid crystal shutter, 16, 17:
Bandpass filter, 20: white light source such as halogen lamp, xenon lamp, 21, 21 ': beam splitter, 22: roof prism, 25: TV camera, 26: video amplifier, 27: image processing unit, 28: microprocessor, 29 : Liquid crystal shutter drive circuit 30, 31: Stepping motor drive circuit.

Claims (3)

[Claims] 1. A position detecting means formed of a thin film for detecting the position of an exposed object based on light from an alignment mark provided on the exposed object, and two illumination lights having different wavelengths. An illumination means for mixing and irradiating the mark, wherein the wavelength of each light is set such that the intensity of the mixed illumination light reflected from the mark is averaged with respect to a change in the film thickness of the mark. In the exposure apparatus, which comprises: an object to be exposed for alignment based on a detection result of the position detection means, a resist applied on the object to be exposed and the mark is exposed by the mixed illumination light. An exposure apparatus comprising a control means for controlling the irradiation time of at least one of the illumination light components so as not to do so. 2. The exposure apparatus according to claim 1, wherein the control unit includes a blocking unit that blocks the illumination light on the optical axis of the illumination unit. 3. The detection means captures the image of the mark in a memory in synchronization with the opening of the blocking means, and executes a position detection process on the image captured in the memory. The exposure apparatus according to claim 2.