JPS62183517A - Exposure apparatus - Google Patents

Abstract

PURPOSE:To reduce the tact time of an apparatus and improve productivity by a method wherein alignment by using alignment marks is not performed for exposure after 2nd shot and an object to be exposed is transferred step by step so as to be placed at a predetermined position accurately by the other means such as a laser interferometer. CONSTITUTION:When 1st mask 1a is exposed, at first the mask 1a is aligned with mask reference marks 17 by a microscope 19. After that, the alignment marks of the mask 1a and the alignment marks of a substrate 3 formed in a previous process are measured by the microscope 19 to align the mask 1a and the substrate 3 and the 1st exposure is performed. When 2nd mask 1b is exposed, the mask 1b is aligned with the mask reference marks 17 by the microscope 19. After that, the substrate 3 is transferred accurately step by step so as to be placed at a predetermined position and be exposed while the position of the substrate 3 is being measured by a laser interferometer 14 and a scourer 15 provided on a stage.

Description

[Detailed Description of the Invention] [Field of the Invention] The present invention relates to an exposure apparatus that prints a pattern image on an original plate, such as a liquid crystal pattern, onto an exposed object with good positional alignment, and particularly relates to an exposure apparatus that prints a pattern image on an original plate, such as a liquid crystal pattern, onto an exposed object with good positional alignment, and particularly relates to an exposure apparatus that prints a pattern image on an original plate, such as a liquid crystal pattern, on an exposed object with good positional alignment. Regarding equipment.

[Conventional Technique #i] Conventionally, display devices used for displaying the output of computers, etc., have generally been based on the CRT system. However, in the CRT system, (1) the device is large in size and heavy;

■High power consumption.

■Flickering on the screen makes your eyes tired.

There were drawbacks such as. Therefore, in recent years, display devices other than the CRT type have been considered, and among them, liquid crystal displays have attracted particular attention.

The process of manufacturing this liquid crystal display is very similar to the semiconductor manufacturing process, and a semiconductor exposure device is used as the exposure device during manufacturing.

Common exposure methods for manufacturing liquid crystal displays include a method in which a mask and a substrate are exposed by contacting each other, and a proximity exposure method in which a gap of several tens of micrometers is maintained between the mask and the substrate for exposure. be. However, with these methods, productivity is low because many pattern defects occur due to mask damage or dust. Therefore, recently, a lens projection system or a mirror projection system is used, and multiple masks of different types are used to separate several exposed areas of the substrate, and the pattern of the mask corresponding to each exposed area is printed. An exposure method for forming a large liquid crystal screen is being considered. This involves changing the mask and aligning the mask substrate for each substrate step, performing static exposure in a lens projection system, and scanning exposure in a mirror projection system, and sequentially performing such partial exposure operations. By repeating this process, a large liquid crystal screen is formed.

An important point to consider when forming a large LCD screen using such divided exposure is that the patterns of multiple masks can be combined into one.
This is the placement accuracy of each mask pattern when transferred onto a single substrate. If this placement accuracy is poor, patterns may overlap or be separated from each other in the boundary area between each mask pattern, making it impossible to obtain sufficient performance of the liquid crystal screen. Therefore, it is necessary to transfer each mask pattern onto the substrate with high placement accuracy.

Normally, four to five overlapping exposure steps are required to form a liquid crystal screen. First, in the first step, each mask is positioned at a predetermined position, the substrate side is measured with a high-precision length measuring device such as a laser interferometer, and the image of a different type of mask is transferred at each step. do. After the second step,
With respect to the pattern printed in the first step, the substrate is again moved in steps in the same manner as in the first step to transfer the mask image in the second and subsequent steps.

The present invention relates to an exposure apparatus that suitably performs alignment of a mask and a substrate in a second step and subsequent steps in which overlay printing is performed on the pattern printed in the first step.

Conventionally, a die-by-die method has been common as a mask and substrate alignment method for this type of device. In the die-by-die method, both the alignment mark made on the mask positioned at a predetermined position and the alignment mark made on the substrate in the previous process are irradiated with light such as a laser, and the light is reflected through the projection optical system and microscope. This system detects the positions of both marks from changes in the amount of light coming in, calculates the amount of misalignment between the mask and the substrate using an arithmetic circuit, and performs a positioning operation to drive the substrate based on the amount of misalignment for each shot. be.

In the die-by-die method, the exposed area of the substrate is divided into several areas and alignment is performed for each shot area. Therefore, positional deviations due to substrate factors such as expansion and contraction due to substrate temperature, positional deviation due to local deformation of the substrate, and projection optical system Positional deviations due to magnification can be corrected, improving alignment accuracy. However, since alignment is performed for each shot,
This has the disadvantage that the time required for alignment (normal shot alignment time of 2 seconds) is added, which increases the takt time of the apparatus and reduces productivity.

[Object of the Invention] In view of the above-mentioned problems of the conventional method, an object of the present invention is to eliminate the alignment time when exposing the second and subsequent masks in an exposure apparatus using a divided exposure method, and to reduce the takt time of the apparatus. The goal is to shorten it and improve productivity.

[Summary of the Invention] In order to achieve the above object, in the present invention, the mask is always positioned at a predetermined position, and the positioning mark of the mask exposed first and the positioning mark of the substrate formed in the previous process are used. Measures the misalignment between the mask and the substrate, and aligns the mask and substrate by driving the substrate side.
Perform exposure.

Next, when exposing the second and subsequent masks, the masks are positioned at a predetermined position, and the substrate side is moved step by step to a predetermined position while being measured by a laser interferometer, etc., and exposure is performed. In this case, the time required for the second and subsequent alignments is not necessary, the takt time of the apparatus is shortened, and productivity is improved.

[Explanation of Examples] Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 shows a schematic configuration of an exposure apparatus according to an embodiment of the present invention. The apparatus shown in the figure is a step-and-scan type exposure apparatus that uses a mirror projection system to expose a large screen by divided scanning.

In the figure, 1 is a photomask on which a printed pattern is formed, and 2 is an X with mask 1 mounted thereon.

This is a mask stage that can move in the Y and θ directions.

3 is a glass substrate on which a large number of pixels and switching transistors for controlling on/off of these pixels are formed by normal photolithography procedures in order to manufacture a liquid crystal display board, and the length of the diagonal line is is about 14 inches square. Reference numeral 4 denotes a substrate stage that can hold the substrate 3 and move in the X, Y, and θ directions. The step movement of the substrate stage 4 is controlled by a precision length measurement system using a laser interferometer (not shown). 5 is a well-known mirror projection system consisting of a combination of a concave mirror and a convex mirror, and the mask stage 2
The pattern image of the mask 1 aligned at a predetermined position is projected onto the substrate 3 at the same size.

Reference numeral 6 denotes an illumination optical system that illuminates the mask 1 at the exposure position with light of a specific wavelength from a light source (not shown), and by exposing the photosensitive layer on the substrate 3 through the pattern on the mask, This is to enable the pattern to be transferred onto the substrate 3. Note that the optical axis of the projection system 5 is made to coincide with the optical axis of the illumination system 6.

7 is a LAB (linear air bearing) that can be moved along two guide rails 8 provided in the Y direction (perpendicular to the page), one of which is movable in the X direction (horizontal direction of the page) and Z direction (direction perpendicular to the page). The other type is a Z-direction restraint type. 9 is a holder (carriage) that holds the mask stage 2 and substrate stage 4 in a fixed relationship;
7, the mask 1 on the mask stage 2 and the substrate 3 on the substrate stage 4 can be integrally transferred.

11 is a mask transport device for sequentially transporting each mask 1 to the mask stage 2; 12 is a gap sensor for detecting the distance between the focal plane of the projection system 5 and the surface of the substrate 3;
For example, an air microsensor or a photoelectric type sensor that detects the distance using reflected light from the substrate 3 is used. Reference numeral 13 denotes a base on which the projection system 5, illumination system 6, and guide rail 8 are mounted in a fixed relationship.

In the apparatus shown in the figure, the surface of the substrate 3 is divided into, for example, four exposed areas, and these exposed areas are sequentially sent to the exposure area under the mask 1 and the projection optical system 5 by step movement of the substrate stage 4. The mask pattern is exposed four times, and the pattern for the liquid crystal display board is printed on the entire surface of the substrate 3.

FIG. 2 is a schematic configuration diagram for explaining the exposure operation after the second step in the apparatus of FIG. 1.

Note that the same or common parts as in FIG. 1 are indicated by the same reference numerals. In Fig. 2, 1a is a photomask on which a pattern is formed on the first printing, and 1b, 1c, and ld are photomasks on which a pattern is similarly formed on the 2nd, 3rd, and 4th printings. . In addition, 14 is a laser interferometer, 1
Reference numeral 5 denotes a scorer, 17 a mask reference mark on the apparatus side, and 19 a microscope for measuring the positioning mark of the mask 1 and the mask reference mark 17, and for measuring the positioning marks of the mask 1 and the substrate 3. Note that in order to show the path of light from the laser interferometer 14, parts of the LAB 7 and the holder 9 are omitted.

In FIG. 2, when exposing the first mask 1a, the mask 1a is first positioned with respect to the mask reference mark 17 on the apparatus side using the microscope 19.

Thereafter, the positioning mark of the mask 1a and the positioning mark of the substrate 3 formed in the previous step are measured using the microscope 19 to position the mask 1a and the substrate 3, and the first exposure is performed.

Next, when exposing the second mask 1b, the mask 1b is first positioned with respect to the mask reference mark 17 on the apparatus side using the microscope 19. After that, the laser interferometer 14
While measuring the position of the substrate 3 using a scorer 15 provided on the stage, the substrate 3 is accurately moved step by step so that the substrate 3 is set at a predetermined position, and exposure is performed.

FIG. 3 shows a schematic configuration of an exposure apparatus according to another embodiment of the present invention. The apparatus shown in the figure is a step-and-repeat type exposure apparatus that exposes a large screen by dividing exposure using a lens projection system.

In the figure, 1 is a photomask on which a printed pattern is formed, and 2 is an X with mask 1 mounted thereon.

This is a mask stage that can move in the Y and θ directions.

3 is a glass substrate on which a large number of pixels and switching transistors for controlling on/off of these pixels are formed by normal photolithography procedures in order to manufacture a liquid crystal display board, and the length of the diagonal line is is about 14 inches square. Reference numeral 4 denotes a substrate stage that can hold the substrate 3 and move in the X, Y, and θ directions. The step movement of the substrate stage 4 is performed by a precision length measurement system using a laser interferometer (not shown). A lens projection system 31 includes a plurality of lenses, and projects a pattern image of the mask 1 aligned at a predetermined position by the mask stage 2 onto the substrate 3. Note that the projection magnification is reduced, enlarged,
Any size of the same size will do. Reference numeral 32 denotes an illumination optical system that illuminates the mask 1 at the exposure position with light of a specific wavelength from a light source (not shown). This is to enable the upper pattern to be transferred onto the substrate 3. Note that the optical axis of the projection system 31 is made to coincide with the optical axis of the illumination system 32.

11 is a mask transport device for sequentially transporting each mask 1 to the mask stage 2, and 13 is a base for mounting the projection system 31, the illumination system 32, and the substrate stage 4 in a fixed relationship.

In the apparatus shown in the figure, the surface of the substrate 3 is divided into, for example, four regions to be exposed, and these regions are divided into the mask 1 and the projection optical system 31 by step movement of the substrate stage 4.
The mask pattern is exposed to light four times by sequentially sending it to the lower exposure area, and a pattern for the LCD panel is printed on the entire surface of the substrate 3.

FIG. 4 is a schematic configuration diagram for explaining the exposure operation after the second step in the apparatus of FIG. 3.

Note that the same or common parts as in FIG. 3 are indicated by the same reference numerals. In FIG. 4, 1a is a photomask on which a pattern is formed in the first printing, lb, 1c, 1d
Similarly, the 2nd, 3rd, and 4th printing is a photomask on which a pattern is formed. In addition, 14 is a laser interferometer, 15 is a scorer, 17 is a mask reference mark on the device side, 1
9 is the positioning mark of mask 1 and mask reference mark 17
This is a microscope for measuring the positioning marks of the mask 1 and the substrate 3.

In FIG. 4, when exposing the first mask 1a, first, the mask 1a is positioned with respect to the mask reference mark 17 on the apparatus side using the microscope 19.

Thereafter, the positioning mark of the mask 1a and the positioning mark of the substrate 3 formed in the previous step are measured using the microscope 19 to position the mask 1a and the substrate 3, and the first exposure is performed.

Next, when exposing the second mask 1b, the mask 1b is first positioned with respect to the mask reference mark 17 on the apparatus side using the microscope 19. After that, the laser interferometer 14
While measuring the position of the substrate 3 using a scorer 15 provided on the stage, the substrate 3 is accurately moved step by step so that the substrate 3 is set at a predetermined position, and exposure is performed.

[Effects of the Invention] As explained above, according to the present invention, in an exposure apparatus using a divided exposure method, alignment is performed using the positioning mark on the original plate and the positioning mark on the exposed object for the first exposure, and For the second and subsequent exposures, alignment using positioning marks is not performed, but a separate device such as a laser interferometer is used to move the exposed object step by step so that it is precisely at the predetermined position, so that the second and subsequent masks can be exposed. It is possible to eliminate the alignment time during the process, shorten the takt time of the device, and improve productivity.

[Brief explanation of drawings]

1 is a schematic configuration diagram of an exposure apparatus according to an embodiment of the present invention, FIG. 2 is a schematic configuration diagram for explaining the exposure operation after the second step in the apparatus of FIG. 1, and FIG. 4 is a schematic configuration diagram of an exposure apparatus according to an embodiment of the present invention, and FIG. 4 is a schematic configuration diagram for explaining the exposure operation after the second step in the apparatus of FIG. 3. 1: Photomask, 2: Mask stage, 3: Substrate, 4: Substrate stage, 5: Mirror projection system, 9: Holder (
carriage), 13: base, 14: laser interferometer,
15: Scoya, 17: Mask reference mark,
19: Microscope, 31: Lens projection system, 32
:Lighting system.

Claims (1)

[Scope of Claims] 1. An exposure apparatus that divides the surface of an exposed object into a plurality of exposed areas and projects images of different types of originals onto each exposed area, which exposes each of the exposed areas. an original plate positioning means for positioning an original plate having a pattern to be projected onto the exposed area at a predetermined position during the process; a positioning mark attached to the original plate and a positioning mark on the exposed object formed in advance in a previous process; an exposed object positioning means for positioning the exposed object with respect to the original plate using the exposure object, and a measuring means for measuring the position of the exposed object, and in the first exposure, after positioning the corresponding original plate. The exposed object is positioned by the exposed object positioning means, and in the second and subsequent exposures, after positioning the corresponding original plate, the exposed object is moved stepwise to a predetermined position based on the measurement result of the measuring means and the exposure is performed. An exposure apparatus characterized by: 2. The exposure apparatus according to claim 1, wherein the measuring means is a laser interferometer. 3. Claim 1 or 2, wherein the exposure device projects an image of the original plate onto the exposed object by integrally scanning the original plate and the exposed object with respect to a projection optical system. Exposure apparatus described in Section 2. 4. The exposure apparatus according to claim 1, wherein the exposure apparatus projects an image of the original plate onto the object to be exposed using a lens. 5. The exposure apparatus according to claim 1, wherein the exposure apparatus exposes the original plate and the object to be exposed in close proximity or in close contact with each other.