JP2014224942A - Proximity exposure machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a proximity exposure machine which monitors the exposure gap between a substrate and a mask.SOLUTION: A proximity exposure apparatus is used for executing exposure of a photomask and a substrate in a state where the photomask and the substrate are brought close to each other at a minute interval and includes a stage 20, a photomask pressing bar 24, an exposure gap sensor 23, substrate position detection sensors 25a- and 25b-1 and a control portion. While the stage 20 mounted with a substrate 22 is caused to ascend, the magnitudes of the gaps between the photomask 21 pressed with the photomask pressing bar and the four corners of the substrate 22 are measured by the exposure gap sensor 23. After the magnitudes of the gaps reach set values, the ascending of the stage 20 is stopped, and the magnitude between the photomask 21 and the central part of the substrate 22 is monitored by the substrate position detection sensors 25a-1 and 25b-1. The control portion executes exposure at the timing when a specified magnitude of the gap is reached.

Description

  The present invention is a so-called proximity exposure machine that performs exposure with a mask and a glass substrate close to each other, and in particular, a resist is applied to the glass substrate and patterned in the process of manufacturing a color filter. The present invention relates to a proximity exposure machine used when exposure is performed using a photomask.

  FIG. 1 is a cross-sectional view showing an example of a color filter substrate used in a color liquid crystal display device as an example of the substrate. The color filter 1 includes a black matrix (hereinafter referred to as BM) 3, a red R colored pixel (hereinafter referred to as R pixel) 4-1, a green G colored pixel (hereinafter referred to as G) on a transparent glass substrate (hereinafter referred to as substrate) 2. Pixel) 4-2, Blue B colored pixel (hereinafter referred to as B pixel) 4-3, transparent electrode 5, photo spacer (hereinafter referred to as PS) 6, vertical alignment (hereinafter referred to as VA) ) 7 are sequentially formed.

  The manufacturing method of the color filter having the above structure is known to use a photolithography method, a printing method, and an inkjet method. FIG. 2 is a flowchart showing a manufacturing process by a commonly used photolithography method. is there. For the color filter, first, as a pretreatment, a step of cleaning the substrate (C1), a step of forming a BM on the substrate (C2), a step of cleaning the substrate (C3), applying a colored photoresist and pre-drying Step (C4) for processing, prebaking step (C5) for drying and curing the colored photoresist, step (C6) for exposing the colored photoresist, step (C7) for developing, step for curing the colored photoresist (C8), a process of forming a transparent electrode (C9), and a process of forming PS and VA (C10) are performed in this order.

  For example, when the pixels are formed in the order of R pixel, G pixel, and B pixel, red R, green G between the process of cleaning the substrate (C3) and the process of curing the colored photoresist (C8). The colored photoresist is changed in the order of blue B, and the process is repeated three times to form R pixels, G pixels, and B pixels.

  In the exposure process in the BM formation process (C2), the process of exposing the colored photoresist (C6), and the process of forming PS and VA (C10), a resist is baked on the substrate to form a pattern.

  FIG. 3 is a view showing a proximity type exposure apparatus as an example of a method used for exposure in this case, and irradiates a substrate having a resist coated on its surface with ultraviolet rays through a photomask (hereinafter referred to as a mask). Thus, the resist surface of an arbitrary pattern is exposed. Proximity exposure equipment passes through a collimation mirror after the difference in the amount of light in the cross section of the integrator lens (compound eye lens) optical path from the illumination light (ultraviolet light) emitted from an exposure lamp using a high-pressure mercury lamp or the like is reduced. In this way, the light becomes substantially parallel light, and the substrate placed on the stage is exposed through a mask. The mask is exposed while floating from the substrate by the exposure gap.

  Compared with the projection exposure method, this exposure method does not require a complicated lens system or a high-precision stage, so it is easy to reduce the cost. Compared with the contact exposure method, the mask and the substrate are not in direct contact with each other, so that the photosensitive agent is peeled off. It has the advantage that it is difficult to cause defects.

  The element size (black matrix or RGB pixel size) in a color filter manufactured by the proximity method is greatly related to the exposure gap (distance between the mask and the substrate).

  That is, when the resist to be used is, for example, a negative type, the size is large when the exposure gap is large and the size is small when the exposure gap is small due to the influence of light diffraction. Therefore, it is necessary to control the exposure gap in order to make the pixel size the target size.

  FIG. 4 shows an example of the exposure gap control method. The stage 10 is lowered in advance, and the substrate 12 is set between the stage 10 and the mask 11. Next, the stage 10 moves up to the target exposure gap. At this time, whether or not the target exposure gap is reached is read by the exposure gap sensor 13 that optically reads the gaps provided at the four corners. Take control. After controlling the exposure gap, exposure is performed.

  As shown in FIG. 5, the exposure gap sensor 13 used at this time includes a light projecting unit 13 a that irradiates light to the mask 11 obliquely, and light 13 b that is irradiated from the light projecting unit and reflected from the lower surface of the mask 11. And a light receiving portion 13e that receives the light 13c irradiated from the light projecting portion 13a and reflected by the surface of the substrate 12 after passing through the lens 13d, and from the position of each light received by the light receiving portion 13e, a mask 11 and the substrate 12 are detected. A part of the light emitted from the light projecting unit 13 a to the mask 11 is reflected by the upper surface of the mask 11, and a part of the light is transmitted into the mask 11. A part of the light transmitted to the inside of the mask 11 is reflected by the lower surface of the mask 11, and a part of the light is irradiated from the lower surface of the mask 11 to the surface of the substrate 12. A part of the light irradiated to the surface of the substrate 12 is reflected by the surface of the substrate 12 and a part of the light is transmitted to the inside of the substrate 12. The light receiving unit 13e of the exposure gap sensor condenses the light 13b reflected by the lower surface of the mask 11 and the light 13c reflected by the surface of the substrate by the imaging lens 13d and forms an image on the light receiving surface of the light receiver 13e. Let In this way, the gap between the mask and the substrate is read.

  In the above-described conventional exposure gap control, when the substrate 12 is actually exposed, there is a possibility that a large difference is caused particularly in the exposure gap between the central portion and the end portion of the glass. FIG. 6 shows a diagram for explaining the reason.

  When the stage 10 rises to the target exposure gap (FIG. 6A), the central portion of the mask 11 receives air pressure due to the stage rise and bends upward in a convex shape (FIG. 6B). As a result, a difference in exposure gap occurs between the mask edge portion where the mask 11 is supported by the mask holding bar 14 and the mask central portion. Therefore, the process waits until the bending disappears, and exposure is performed at the timing when the bending disappears (FIG. 6C).

  However, since the actual deflection is not monitored, the exposure timing varies, so that the pixel size varies due to the influence of the exposure gap difference between the central portion and the end portion of the substrate 12. There was a problem that.

  Further, since the exposure gap is monitored only at the four corners when the substrate is inserted, there is a problem that the exposure gap at the center cannot be monitored.

JP-A-11-204394

  In view of the above problems, an object of the present invention is to provide a proximity exposure machine that monitors an exposure gap between a substrate and a mask.

Therefore, the invention described in claim 1 of the present invention is
A proximity exposure machine that performs exposure in a state where a photomask and a substrate are close to a minute distance,
A stage, a photomask holding bar, an exposure gap sensor, a substrate position detection sensor, and a control unit;
While raising the stage on which the substrate is placed, measure the size of the gap between the photomask pressed by the photomask holding bar and the four corners of the substrate with the exposure gap sensor, and after reaching the set exposure gap, The proximity exposure machine is characterized in that the rising is stopped, the size of the gap between the photomask and the central portion of the substrate is monitored by the substrate position detection sensor, and the control unit performs exposure at the timing when the predetermined gap is reached. .

The invention according to claim 2 of the present invention is
2. The proximity exposure apparatus according to claim 1, wherein a plurality of substrate position detection sensors are provided, and the exposure gap is monitored by detecting a plurality of substrate positions.

The invention according to claim 3 of the present invention is
3. The proximity exposure machine according to claim 1, wherein the substrate position detection sensor is provided in parallel with the photomask surface.

  By monitoring the exposure gap, exposure can be performed at the timing of the target exposure gap. As a result, the difference in the exposure gap in the photomask is reduced, and the variation in the pixel size of the color filter due to the change in the exposure gap can be reduced.

  Even when the stage surface on which the substrate is placed tilts and rises, the exposure gap difference from the photomask within the substrate surface can be monitored by monitoring the exposure gaps at multiple locations with multiple substrate position detection sensors. And the dimensional variation of the color filter due to the fluctuation of the exposure gap can be reduced.

  Since the change amount of the gap can be monitored by monitoring the position of the substrate, there is no need for a measurement pattern installed on the mask for monitoring the change amount of the gap as in the prior art.

The figure which shows an example of the color filter substrate used for a color liquid crystal display device in a cross section. The flowchart which shows the CF board | substrate manufacturing process by the photolithographic method. The figure which shows the exposure apparatus of the conventional proximity system. The figure which shows an example of the method of exposure gap control. The figure which shows a gap sensor. The figure which shows the conventional exposure gap control. (A) is a figure which shows the case where a stage raises to the target exposure gap. (B) is a figure which shows that the center part of a mask will bend upward convexly. FIG. 6C is a diagram showing that exposure is performed at a timing at which the bending disappears. The figure which shows an example of schematic structure of the proximity exposure machine of this invention. The figure which shows that the center part of a board | substrate will bend in convex shape. The figure for demonstrating the board | substrate position detection sensor of the proximity exposure machine of this invention. (A) is a figure which shows the light emitting element of a board | substrate position detection sensor. (B) is a diagram showing that the edge of the back surface of the substrate is detected when the central portion where the substrate position detection sensor is bent in a convex shape reaches the exposure gap. The figure which shows that the part which shifted | deviated from the center part of the board | substrate which concerns on this invention will bend upward convexly. The figure which shows the example of installation of a board | substrate position detection sensor.

  Hereinafter, an embodiment for carrying out a proximity exposure apparatus of the present invention will be described with reference to the drawings.

  FIG. 7 is a view showing an example of a schematic configuration of the proximity exposure apparatus of the present invention. The proximity exposure machine shown in FIG. 7 includes a stage 20, a mask holding bar 24, an exposure gap sensor 23, substrate position detection sensors 25a-1 and 25b-1, and a control unit (not shown). .

  The stage 20 is applied with a resist (for example, a resist for BM or a coloring resist) and a dried substrate 22 is placed thereon, and the stage 20 is raised in the direction of an arrow 26.

  The mask 21 is pressed at two end sides facing each other by a photomask holding bar 24.

  When the stage 20 is raised in the direction of the arrow 26, the exposure gap sensor 23 measures the size of the exposure gap between the four corners of the substrate 22 and the mask 21. The stage 23 has a mechanism in which its four corners rise independently, and since the exposure gap sensor 23 is provided above the four corners of the substrate 21, the four corners of the substrate 22 are kept at the set exposure gap positions. Be drunk.

  The size of the exposure gap to be set is set with an allowable range such as 100 μm ± 30 μm. The exposure gap is changed depending on the exposure target.

  When the stage 20 is raised in the direction of the arrow 26, as shown in FIG. 8, the central portion of the substrate 22 is bent in a convex shape, so that the gap size is not uniform at the four corners and the central portion of the substrate 22. Absent. For this reason, in the conventional proximity exposure apparatus, after measuring the gaps at the four corners of the substrate, the gap is set, and after a certain period of time has passed until the center portion of the substrate 22 is not bent, exposure is performed thereafter. . However, when the passage of time is short, the convex bend does not disappear, and conversely when it is too long, it bends in a concave shape, so that the exposure gap varies in the plane of the substrate 22.

  Therefore, the proximity exposure machine of the present invention includes substrate position detection sensors 25a-1 and 25b-1 (FIG. 7). As shown in FIG. 9A, the substrate position detection sensor includes a light emitting element 25a-1 (not shown) that emits a minute spot light 25c-1 and a light receiving sensor 25b-1 that receives the minute spot light.

  The substrate position detection sensors (25a-1, 25b-1) are provided at the exposure gap position of the substrate 22 in parallel with the photomask surface, and when the convex bent central portion reaches the exposure gap, the substrate 22 is detected. The edge of the back surface of the sheet is detected (FIG. 9B). Exposure is performed at the detected timing. The substrate position detection sensor detects the edge of the back surface of the substrate, and further determines the position of the substrate (the position of the substrate after detecting the edge of the substrate that is free from bending) based on the amount of light received by the minute spot light. A sensor that can detect the amount is desirable.

  The control unit is a substrate position detection sensor and controls to perform exposure when it is detected that the exposure gap is within the set range by (25a-1, 25b-1).

  FIG. 8 shows that the central portion of the substrate 22 bends in a convex shape when the stage 20 is raised in the direction of the arrow 26, but the substrate 22 placed on the stage 20 as shown in FIG. When it rises slightly tilted without rising in the horizontal state, the portion shifted from the central portion of the substrate 22 bends upward in a convex shape. Therefore, in the present invention, as shown in FIG. 11, in addition to (25a-1, 25b-1), (25a-2, 25b-2) and (25a-3, 25b-3) as substrate position detection sensors. Is provided.

  In this way, the control unit can control the exposure so that the entire surface of the substrate 22 is exposed at a timing within the allowable range of the exposure gap.

  The procedure for exposure by the proximity exposure apparatus according to the present invention will be described with reference to FIG.

  First, the target exposure gap is set to 100 μm ± 30 μm, and a setting range is set in the control unit. Next, the substrate 22 coated with BM resist and subjected to pre-exposure processing is set on the stage 20. Thereafter, the stage 20 is raised, and the exposure gap at the end face is controlled using the exposure gap sensors 23 at the four corners. In this way, the exposure gaps at the four corners are all contained within the target exposure gap.

  However, since the substrate 22 is bent upward at this point, the substrate position detection sensors (25a-1, 25b-1) at the center of the substrate remain OFF (exposure gap is 100 μm ± 30 μm). The exposure is not started.

  After a certain period of time, the convex deflection disappears, and the substrate position detection sensors (25a-1, 25b-1) in the center of the substrate detect the edge of the back surface of the substrate 22, and exposure is started at this timing. The

  In the above description, the case of a color filter has been exemplified, but the present invention is not limited to this, and the present invention can be widely applied to a proximity exposure machine when a mask pattern is exposed on a substrate.

  As described above, according to the proximity exposure apparatus of the present invention, the substrate position sensor can monitor the fact that the substrate bent in a convex shape has disappeared, and exposure can be performed at that timing. The exposure can be performed without any variation in the size of the substrate and the size within the substrate surface.

DESCRIPTION OF SYMBOLS 1 ... Color filter 2 ... Transparent glass substrate 3 ... Black matrix (BM)
4-1 ... R pixel 4-2 ... G pixel 4-3 ... B pixel 5 ... transparent electrode 6 ... PS
7 ... VA
DESCRIPTION OF SYMBOLS 10 ... Stage 11 ... Mask 12 ... Board | substrate 13 ... Gap sensor 13a ... Light projection part 13b ... Light reflected by the lower surface of a mask 13c ... Reflected by the surface of a board | substrate Light 13d ... Lens 13e ... Light receiving unit 14 ... Mask holding bar 20 ... Stage 21 ... Mask 22 ... Substrate 23 ... Exposure gap sensor 24 ... Mask holding bar 25a -1 to 25a-3... Light emitting unit 25b-1 to 25b-3 of the substrate position detection sensor.

Claims (3)

A proximity exposure machine that performs exposure in a state where a photomask and a substrate are close to a minute distance,
A stage, a photomask holding bar, an exposure gap sensor, a substrate position detection sensor, and a control unit;
While raising the stage on which the substrate is placed, measure the size of the gap between the photomask pressed by the photomask holding bar and the four corners of the substrate with the exposure gap sensor, and after reaching the set exposure gap, A proximity exposure machine characterized in that the rising is stopped, the size of the gap between the photomask and the central portion of the substrate is monitored by a substrate position detection sensor, and the control unit performs exposure at a predetermined gap.   2. The proximity exposure apparatus according to claim 1, wherein a plurality of substrate position detection sensors are provided, and the exposure gap is monitored by detecting a plurality of substrate positions.   The proximity exposure machine according to claim 1, wherein the substrate position detection sensor is provided in parallel with the photomask surface.

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