JP2011102834A - Substrate exposure apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simply structured substrate exposure apparatus capable of reducing variations in a gap between a substrate to be exposed and a photomask, at a proximity exposure without having to prepare special peripheral equipment for correcting the deflection, thereby attaining reduction in the variations in the line width and the film thickness of a pattern formed on the substrate to be exposed. <P>SOLUTION: The substrate exposure apparatus is equipped with an exposure stage for holding the substrate to be exposed, on which a photosensitive film is formed, on its upper surface, and a mask holder for holding a photomask (original plate) of a rectangular shape in planar view over the upper surface of the substrate to be exposed, by making the photomask face the substrate to be exposed, for performing pattern exposure from above the substrate to be exposed, and performs pattern exposure to the substrate to be exposed by providing a predetermined proximity gap between the photomask and the substrate to be exposed, and radiating light from above the photomask. The exposure stage has the same deflection amount as that of the photomask. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a substrate exposure apparatus that irradiates light from above a photomask and performs pattern exposure on a substrate to be exposed that is opposed to the photomask at a predetermined minute interval with light that has passed through the photomask.

  A conventional substrate exposure apparatus includes an exposure stage that holds a glass or plastic substrate (hereinafter referred to as an exposure substrate) on a surface of which a photosensitive film made of a photosensitive resin or the like is formed, and an upper side of the exposure substrate. A mask holder is provided for holding a photomask having a predetermined pattern on the upper surface of the substrate to be exposed, in order to perform pattern exposure. There are some exposure machines that bring the photomask and the exposed substrate into close contact during pattern exposure, but in the case of contact exposure, the photomask and the exposed substrate are damaged by foreign matter entering between the photomask and the exposed substrate. Cheap. Therefore, in pattern exposure, a proximity exposure method is used in which pattern exposure is performed on the exposed substrate by irradiating light from above the photomask with a predetermined minute gap (proximity gap) between the photomask and the glass substrate. Substrate exposure apparatuses (proximity type exposure machines) are used.

  However, in the case of a proximity type substrate exposure apparatus, since there is a gap below the photomask, the photomask is likely to be bent due to its own weight during pattern exposure. In recent years, when manufacturing CF (color filter) substrates for liquid crystal display devices, which have been increased in size, using a series of photolithographic methods such as pattern exposure and development using colored photosensitive resin, the photomask used is also large. It has become. When the size of the photomask is increased, the photomask's own weight is naturally increased, and the deflection of the photomask during the proximity exposure is also increasing. If the distance (gap) between the photomask and the substrate to be exposed varies in the proximity exposure, the line width and film thickness of the pattern formed on the substrate to be exposed by pattern exposure and development will vary. Become. In recent years, the demand for deflection correction has become more and more severe with the increase in size of the mask accompanying the increase in size of the substrate and the increase in the definition of pixels.

  When the substrate to be exposed is a CF (color filter) substrate for a liquid crystal display device, if the CF pixels in the CF substrate formed by pattern exposure and development have variations in line width and film thickness, the CF substrate is incorporated. The liquid crystal display device cannot exhibit desired display performance such as color variation. Therefore, it is necessary to reduce the gap variation between the photomask and the CF substrate during pattern exposure. One of the causes of variations in the gap between the substrate to be exposed and the photomask during proximity exposure is bending due to the photomask's own weight, so an apparatus and method have been proposed to reduce the bending due to the photomask's own weight. Yes.

  In the conventional exposure apparatus, as shown in the schematic sectional view of FIG. 1, the photomask (original plate) (10) is vacuum-fixed by the original plate support adsorption groove (1) on the mask holder (20). In such a conventional support mechanism, since the photomask is supported only by the outer edge portion, there is a problem that the exposure gap (70) in the center portion is narrowed due to bending due to its own weight. Patent Document 1 discloses an exposure apparatus that includes a support member that supports a mask from below and a pressing means of a heavy stone that applies a predetermined pressure to the mask from above on the outside of a support point of the support member. . Further, in Patent Document 2, a mask holder that holds two sides on both sides and edge portions on both sides of a photomask held on the mask holder are provided in the same manner as the technique disclosed in Patent Document 1. A substrate exposure apparatus having a mechanism for variably pressing from above according to the amount of deflection of a mask has been proposed. Here, as the deflection correction mechanism, the edge of the mask is pressed down by the tip portions made of bearing-like resin of a plurality of pressing members provided at predetermined intervals on the upper surface of the connecting member outside the mask, and the entire connecting member is lowered. Thus, the edge of the mask is pressed at the tip, and the central part of the mask is lifted by the principle of scissors so as to cancel out the bending and become generally flat as a whole.

  Also, in recent years, the demand for deflection correction has become stricter with the increase in size of the mask accompanying the increase in size of the substrate and the increase in the definition of pixels, and in order to increase the durability of the pressing member for correction, for example, a patent As disclosed in Document 3, a CF substrate exposure apparatus is used that presses the edge of a mask with a correction bar using ultrahigh molecular weight polyethylene as a contact site, while applying a load from above.

  However, the techniques disclosed in Patent Documents 1 to 3 have a problem in that special peripheral equipment is separately required, the apparatus itself is complicated, and the cost is high. Further, the mask deflection is corrected to some extent by the deflection correction bar, and variations in the exposure gap can be reduced. However, the exposure gap in the surface may change due to deterioration of the deflection correction bar or the like. As described above, when the variation in the in-plane exposure gap becomes large, a negative effect is exerted on the quality such as photolithography characteristics (line width, film thickness) or pattern transfer accuracy. In addition, the overlay accuracy of each layer constituting the CF also deteriorates, and it takes time to adjust the offset, leading to a reduction in the time operation rate. Therefore, in order to reduce this variation, there has been a problem that the deflection correction bar needs to be replaced periodically.

Japanese Patent Laid-Open No. 09-306832 JP 2001-109160 A JP 2009-260172 A

  The present invention has been made in view of the above-described problems, has a simple structure, and reduces gap variation at the time of proximity exposure between a substrate to be exposed and a photomask without preparing special peripheral equipment for deflection correction. Accordingly, an object of the present invention is to provide a substrate exposure apparatus that can reduce the line width and film thickness variation of the pattern formed on the substrate to be exposed.

  The invention according to claim 1 of the present invention includes an exposure stage for holding an exposed substrate on which a photosensitive film is formed on an upper surface, and a photomask (original) having a rectangular shape in plan view for performing pattern exposure from above the exposed substrate. And a mask holder that holds the substrate on the upper surface of the substrate to be exposed, with a predetermined minute gap between the photomask and the substrate to be exposed, and light from above the photomask. In the substrate exposure apparatus for performing pattern exposure on the substrate to be exposed by irradiation, the exposure stage has the same deflection amount as that of the photomask.

  In the invention according to claim 2 of the present invention, the exposure stage is supported on its two sides by an exposure stage support, the exposure stage support is movable, and the support interval (span) between the two sides is changed. The substrate exposure apparatus according to claim 1, further comprising a mechanism that makes the deflection amount of the exposure stage variable.

The invention according to claim 3 of the present invention is the substrate exposure apparatus according to claim 1 or 2, wherein the exposure stage is made of fused silica glass or synthetic quartz glass.

  In the substrate exposure apparatus of the present invention, the distance (exposure gap) between the photomask and the substrate to be exposed held on the exposure stage is made uniform by setting the exposure stage to the same deflection amount as the exposure photomask. I can do it. Thereby, it is possible to reduce the line width and film thickness variation of the pattern formed on the substrate to be exposed.

  Further, in the substrate exposure apparatus of the present invention, the exposure stage is supported on the two sides by the exposure stage support, and the exposure stage support is moved to change the support interval (span) between the two sides. A mechanism for adjusting the amount of deflection of the exposure stage according to the amount of deflection of the photomask is provided. Therefore, it is possible to change the amount of deflection of the exposure stage in accordance with, for example, a photomask having a different thickness or size and a different amount of deflection. Therefore, it is not necessary to forcibly correct the amount of bending of the photomask with the conventional deflection correction bar. As a result, there is little damage to the photomask, and the influence on quality due to deterioration of the deflection correction bar is reduced. According to the substrate exposure apparatus of the present invention, the gap variation during the proximity exposure between the substrate to be exposed and the photomask is reduced, and the quality variation such as the line width and film thickness of the photosensitive film pattern obtained after pattern exposure and development is reduced. Can be reduced.

Schematic explaining the mask deflection correction in a cross section in a conventional substrate exposure apparatus. The schematic which shows the principal part in one Embodiment of the exposure apparatus of this invention, and demonstrates a photomask bending and exposure stage bending by a cross section.

  Hereinafter, an example of an embodiment of a substrate exposure apparatus according to the present invention will be described with reference to the drawings, taking a CF (color filter) substrate for a liquid crystal display device as an example.

  FIG. 2 is a side view showing a main part of an example of the substrate exposure apparatus of the present invention, illustrating the photomask bending and the exposure stage bending in section, and is a side view seen from the short side direction of the photomask (10). is there. That is, to perform pattern exposure from above an exposure stage (60) that holds an exposed substrate (50) such as a glass substrate having a photosensitive film made of a photosensitive resin or the like on its upper surface, and the exposed substrate (50). A mask holder (20) holding a photomask (10) having a rectangular shape in plan view at both ends of two sides in the normal longitudinal direction and facing the substrate to be exposed (50) above the substrate to be exposed (50), An exposure gap (70) having a predetermined minute interval is formed between the photomask (10) and the substrate to be exposed (50), and parallel light is emitted from a light source (not shown) located above the photomask (10). A substrate exposure apparatus that performs pattern exposure on a substrate to be exposed (50) by irradiation.

  The exposure stage (60) of the substrate exposure apparatus of the present invention is made of a material having substantially the same amount of deflection as the photomask (10) to be used. In this exposure stage (60), for example, two sides opposite to the two sides of the photomask (10) are carried by the exposure stage support (80). At least one of the exposure stage support (80) is movable, and the exposure stage support (80) is moved to change the carrying interval (span) between the two sides, thereby deflecting the photomask (10). And a mechanism for adjusting the amount of deflection of the exposure stage (60). Therefore, for example, it is possible to change the deflection amount of the exposure stage in accordance with a photomask having different thicknesses or dimensions and different deflection amounts.

  In the present embodiment, a rectangular plate material made of fused silica glass or synthetic quartz glass having a thickness of 8 to 10 mm, which is the same material as the photomask, can be used for the exposure stage. The amount of bending of the rectangular plate material can be calculated by the following mathematical formula (1).

W = k (ρ / E) (l ⁴ / t ² ) (1)
Here, W: self-weight deflection amount, E: Young [GPa], k: constant (thermal expansion coefficient [10 ⁻⁷ / ° C.]), l: supported span [mm], ρ: density [g / cm ³ ], t: Thickness [mm]
When the substrate exposure apparatus of the present invention is used in the current apparatus, the photomask holding position and the exposure stage plate thickness are fixed, and at least one movable exposure stage support (80) is moved to move two sides. By changing the support interval (span) 1 between them, the deflection amount of the exposure stage (60) is adjusted in accordance with the deflection amount of the photomask (10).

  The substrate exposure apparatus according to the present invention is provided with a master support suction groove (1) for fixing two sides of the photomask (10) by vacuum suction. The original support suction groove (1) is composed of a suction hole of φ2 mm connected to a vacuum suction device (not shown). The suction force generated by the vacuum suction device fixes the photomask (10) in the original plate support adsorption groove (1). In the example of this embodiment, the dimension of the photomask is 550 mm in the long side direction and 450 mm in the short side direction, but the dimension of the photomask may be larger than this. Further, it is needless to say that the shape and interval of the vacuum suction groove are not limited to the above values, and can be selected depending on the size, thickness and shape of the photomask.

  As described above, depending on the type of photomask set in the exposure apparatus, the form of bending (the amount of bending, the portion where the bending occurs, etc.) that occurs in the photomask due to its own weight varies. In the substrate exposure apparatus of the present invention, the exposure gap is kept in a stable region by flexing the exposure stage in the same manner as the photomask without intentionally correcting the deflection of the photomask. In the figure, for the sake of explanation, the deflection is shown largely. However, since a material having high rigidity is used for both the photomask and the exposure stage, the exposure gap variation due to both deflections in the substrate exposure apparatus of the present invention is minimal. It becomes.

  Specific examples of the present invention will be described below.

<Evaluation conditions>
The following conditions were set as basic exposure conditions.
Photomask: 10mm thick synthetic quartz mask (Young's modulus 74GPa)
Dimensions 450 x 550mm
Measurement substrate: Raw glass, dimension 400 × 500 mm, thickness 0.6 mm
Exposure stage: Dimensions 420 x 520mm
Set exposure gap: 100 μm.

<In-plane exposure gap distribution evaluation>
Using a conventional substrate exposure apparatus shown in FIG. 1A (condition 1), a photomask is sucked and fixed in the original plate supporting suction groove 1 of the mask holder, and the distance (gap) between the exposed substrate and the photomask facing each other ) Was measured. Note that the gap was measured at 25 points on a line passing through the central portion of the photomask and intersecting the sides at right angles. As a result, in (Condition 1), the gap value near the center was small, and the gap value on the side of the photomask was large. The gap variation was 37 μm.

On the other hand, using the substrate exposure apparatus of the present invention (Condition 2), using a fused silica glass having a thickness of 10 mm as an exposure stage and a supporting span of 410 mm,
In the same manner as in 1), the distance (gap) between the opposite substrate to be exposed and the photomask was measured. Similarly, the gap was measured at 25 points on a line passing through the central portion of the photomask and intersecting the sides at right angles. As a result, in (Condition 2), there was little variation in the gap value near the center and the gap value on the side of the photomask, and the variation in gap was reduced to 12 μm.

DESCRIPTION OF SYMBOLS 1 ... Master support adsorption groove 10 ... Photomask 20 ... Mask holder 50 ... Substrate to be exposed 60 ... Exposure stage 70 ... Exposure gap 80 ... Exposure stage support

Claims (3)

An exposure stage that holds the substrate to be exposed on which the photosensitive film is formed on the upper surface, and a photomask (original plate) having a rectangular shape in plan view facing the substrate to be exposed in order to perform pattern exposure from above the substrate to be exposed. A mask holder for holding on the upper surface of the exposure substrate, and exposing the pattern to the substrate by irradiating light from above the photomask with a predetermined minute gap between the photomask and the substrate to be exposed. In the substrate exposure apparatus to perform,
The substrate exposure apparatus, wherein the exposure stage has the same deflection amount as the photomask.   The exposure stage is supported by an exposure stage support on its two sides, the exposure stage support is movable, and the amount of deflection of the exposure stage is variable by changing the support interval (span) between the two sides. The substrate exposure apparatus according to claim 1, further comprising a mechanism.   The substrate exposure apparatus according to claim 1, wherein the exposure stage is made of fused silica glass or synthetic quartz glass.

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