JP2014013303A - Exposure device for color filter and method for manufacturing color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exposure device that causes little decrease in illuminance and no decrease in productivity per unit time even when illumination light to a fly eye lens located in an optical path of the light is physically blocked so as to adjust a collimation half angle.SOLUTION: A proximity exposure device is provided, in which a photomask having a predetermined pattern is laid close to a substrate coated with a photosensitive resin and exposed to exposure light guided transmitted through a fly eye lens via a condensing mirror and guided by a concave mirror. A reflection mirror for reflecting light to the condensing mirror is disposed on a light-entering surface side in a periphery of the fly eye lens; and a light-shielding layer for adjusting a collimation half angle is formed on a light-transmitting surface side of a portion where the reflection mirror is disposed.

Description

  The present invention relates to an exposure apparatus and a manufacturing method, and more particularly to an exposure apparatus for a color filter that transfers a mask pattern of a mask onto a substrate of a flat panel display such as a liquid crystal display or an organic EL display, and a manufacturing method of the color filter. .

  A photolithographic method is generally used for manufacturing color filters. In pattern transfer in the photolithographic method, a proximity exposure method in which exposure is performed by bringing a photomask and an exposure target substrate close to each other, and a predetermined mask pattern is projected through an optical system without bringing the mask and the exposure substrate close to each other. There is a projection exposure method to transfer.

  In the production of color filters, the proximity exposure method is cheaper than the projection exposure method because of the initial investment cost, etc., so the initial proximity exposure method is often used, and the proximity exposure method is still used today. There are many.

  In recent years, the panel display quality of mobile devices for mobile devices has been drastically improved, the precision has been improved in accordance with the needs of the market, and the individual patterns required for color filters have been further refined. It is approaching the resolution limit of the exposure machine in the system. Therefore, as a method for adjusting the spectrum of the exposure bright line using a bright line cut filter or the like, a method for adjusting the spectrum of the exposure bright line using the bright line cut filter has been proposed (Patent Document 1).

  In the proximity exposure method, the pattern shape / characteristic value and the resolution to be transferred change as the distance (exposure gap) between the photomask and the substrate surface to be exposed varies. In general, increasing the exposure gap decreases the pattern resolution, but the anisotropy of the collimation half angle (angle θ with respect to the optical axis of the light beam) becomes more noticeable as the exposure gap increases. It has been proposed to improve the anisotropy of the collimation half angle (angle θ with respect to the optical axis of the light beam) by changing from a rectangle to a circle (Patent Document 2).

  In the production of a high-definition color filter, it has been proposed to use a band-pass filter that cuts out ultraviolet rays of 350 nm or more and passes only a specific wavelength with respect to improvement of fine pattern transfer in the proximity exposure method (Patent Document 3).

  As a method for adjusting the collimation half angle, it is common to physically shield a fly-eye lens (integration lens) located in the optical path of exposure light. However, since the adjustment of the collimation half angle is performed by physical light shielding of the fly-eye lens, a reduction in illuminance is inevitable.

In this case, since the fly-eye lens (integration lens) is shielded along the element lens constituting the fly-eye lens, the illuminance decreases in proportion to the exposure light being blocked, that is, in proportion to the shield area. . The amount of exposure (mJ / cm ² ) is the illuminance (mW / cm ² ) multiplied by time (sec). When the illuminance decreases, the tact increases and the productivity per unit time decreases. It will be a disadvantage.

To compensate for the decreased illuminance, the output of the exposure light source is increased, the optical design of the condenser mirror is adjusted, the distance between the light source and the fly-eye lens (integration lens) is adjusted, and a condenser lens is installed in front of the fly-eye lens (fly The light is condensed in the non-light-shielding area of the eye lens).

  When examining high-definition support in existing exposure tools, there is a problem with the additional lamp space, and the optical redesign of the condensing mirror requires replacement of the condensing mirror, making it necessary to adjust collimation for each product type. Become. In addition, the adjustment of the distance between the light source and the fly-eye lens is an operation for moving the condenser mirror back and forth in the optical path direction, and it is difficult to provide such a movable space in the existing machine.

  In addition, it is possible to install a condenser lens in front of a fly-eye lens in a small exposure machine, but in a large exposure machine, the condenser lens diameter becomes large. Due to the installation, it is difficult to adjust to an arbitrary collimation half angle.

JP 2001-296666 A JP 2008-158282 A JP 2007-94310 A

  In the present invention, due to the physical light shielding to the fly-eye lens located in the optical path of the irradiation light, which is performed to adjust the collimation half angle, there is little decrease in illuminance, no decrease in productivity per unit time, An object of the present invention is to provide an exposure apparatus capable of ensuring quality.

As means for solving the above problems, the invention according to claim 1
A proximity exposure apparatus that exposes exposure light through a concave mirror by bringing a photomask having a predetermined pattern close to a substrate coated with a photosensitive resin, passing through a condensing mirror, and passing through a fly-eye lens. And
A reflection mirror for returning to the condenser mirror is provided on the light incident surface side of the fly eye lens peripheral portion, and a collimation half-angle adjusting light shielding layer is provided on the light passage surface side of the portion where the reflection mirror is provided. The color filter exposure apparatus. The invention according to claim 2 is the color filter exposure apparatus according to claim 1, wherein the collimation half angle is 0.5 deg to 1.7 deg.

  Further, in the invention described in claim 3, the reflecting mirror returns exposure light including ultraviolet light and visible light, which is irradiated to the light shielding layer, to the condenser mirror. 3. The color filter exposure apparatus according to claim 1, wherein the color filter exposure apparatus is attached at an angle of.

  The invention according to claim 4 is the color filter exposure apparatus according to any one of claims 1 to 3, wherein an Al vapor deposition film is provided on the surface of the reflecting mirror. It is.

  A fifth aspect of the present invention is a color filter manufacturing method using the color filter exposure apparatus according to any one of the first to fourth aspects.

  According to the present invention, in order to increase the pattern resolution, even if the fly-eye lens located in the optical path of the irradiation light is physically shielded and the collimation half angle is adjusted to 0.5 deg to 1.7 deg. The increase can be suppressed to the limit and productivity per unit time can be maintained.

It is the schematic block diagram which showed one Embodiment of the exposure apparatus for color filters of this invention. It is the conceptual diagram which showed the structure of the fly eye lens unit of this invention. It is the conceptual diagram which showed the optical path by the reflective mirror in the exposure apparatus for color filters of this invention. It is the conceptual diagram which showed the general fly eye lens unit. It is the conceptual diagram which showed the distance f from the concave mirror 6 to the exposure irradiation surface 7, and the collimation half angle (theta). In the exposure apparatus for color filters of this invention, it is a conceptual diagram of the fly eye lens unit which provided the reflective mirror and the light-shielding plate. It is the conceptual diagram which showed the exposure state by a common exposure apparatus. FIG. 6 is a relationship diagram between line width and optical intensity, showing the influence of a collimation half angle (1.0 deg, 2.0 deg).

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic block diagram of an optical system of an exposure apparatus in proximity exposure according to the present invention. Exposure light 3 emitted from an exposure light source (mercury lamp) 1 is collected by a condenser mirror 2, enters a fly-eye lens unit 5 through a plane mirror 4, and passes through the fly-eye lens unit 5. 3 is irradiated to the exposure irradiation surface 7 through the concave mirror 6.

  FIG. 2 shows the configuration of the fly-eye lens unit 5 according to the present invention. The element lens 13 constituting the fly-eye lens unit 5 and the element elements other than 12 at the center of the fly-eye lens unit 5 among the 56 element lenses. The reflecting mirror 8 and the light shielding plate 9 are provided in this part.

  FIG. 3 shows an optical path by the reflecting mirror 8 in the color filter exposure apparatus of the present invention, and the exposure light 3 other than the twelve element lenses 13 constituting the fly-eye lens unit 5 is reflected by the reflecting mirror 8. The reflected light returns to the condenser mirror 2 and passes again through the 12 element lens 13 portions constituting the fly-eye lens unit 5 toward the exposure irradiation surface 7.

  The reflecting mirror 8 is covered with a metal vapor deposition film, but a vapor deposition film such as Al (aluminum) having a high reflectance is suitable.

  FIG. 4 shows a fly-eye lens unit 5 composed of 56 general element lenses 13. When the collimation half angle is adjusted to 1.0 deg within 0.5 deg to 1.7 deg, the outer peripheral portion of the fly-eye lens unit 5 is shielded by the light shielding plate 9 along the element lens, thereby the center portion. Only the element lens 13 located at is used.

  FIG. 4 shows the opening size 2r of the fly-eye lens 5 constituting the fly-eye lens unit 5, and FIG. 5 shows the distance f from the concave mirror 6 to the exposure irradiation surface 7 and the collimation half angle θ. The distance from the fly-eye lens unit 5 to the concave mirror 6 and the distance from the concave mirror 6 to the exposure irradiation surface 7 are designed to be the same value.

  FIG. 6 shows a fly-eye lens unit 5 provided with a reflecting mirror 8 and a light-shielding plate 9 according to the present invention, leaving the 12 element lenses 13 at the center of the fly-eye lens unit, and an exposure light source (mercury lamp). A reflecting mirror 8 is provided on one side, and a light shielding plate 9 is provided on the exposure irradiation surface 7 side. The exposure light 3 passes only through a region (fly-eye lens 13) that is not shielded by the reflecting mirror 8 and the light shielding plate 9, and the region that is shielded by the light shielding plate 9 is reflected by the reflecting mirror 8 to the condenser mirror 2. And reflected. Basically, the reflecting mirror 8 and the light shielding plate 9 are designed to have the same dimensions.

  FIG. 7 shows an exposure state by a general exposure apparatus. Since exposure light is not parallel light, it affects resolution.

  The collimation half angle is determined by the relationship between the size (2r) of the integrator lens size and the distance from the integrator lens to the concave mirror 6. The smaller the size (2r) of the integrator lens and the greater the distance from the integrator lens to the concave mirror 6, the smaller the collimation half angle.

When the collimation half angle is calculated, it is obtained from the distance f from the concave mirror 6 to the exposure irradiation surface 7 and the size 2r of the opening of the fly eye lens 5 of the fly eye lens unit, and the collimation half angle θ (deg) is Tan ⁻¹ ( r / f).

  A wavelength selection filter is used as necessary. The wavelength selection filter is a band-pass filter that cuts out ultraviolet rays of 350 nm or more and passes only a specific short wavelength, and is installed immediately before or immediately after the fly-eye lens unit 5. Also, the filter size is set to a size that can cover more than the condensed light region. The longer the wavelength, the wider the intensity distribution after transmitting through the mask, and the more difficult it is to resolve a fine pattern. In particular, this tendency becomes strong at a wavelength of 350 nm or more.

  The collimation half angle is adjusted to 0.5 to 1.7 ° and is adjusted by shielding the fly-eye lens unit 5 with a light shielding plate and changing the size (2r) of the non-light shielding region. The smaller the collimation half angle, the narrower the intensity distribution and the higher the resolution. However, when the angle is lower than 0.5 °, distortion of the shape occurs. On the other hand, when the angle is larger than 1.7 °, the entire surface is rounded due to the spread of the intensity distribution.

  In order to make the half angle of the collimation isotropic in all directions, the element lens 13 of the fly-eye lens unit 5 is close to a circle. Also, the overall shape of the lens combining the elements is assumed to be nearly circular. Ideally, it is desirable to make a circular fly-eye lens unit 5 by combining circular elements. However, in consideration of loss of light quantity, a method of combining polygonal elements or the like is used. The collimation half angle is isotropic in all directions on the surface of the substrate to be exposed, and the error in all directions is preferably within ± 0.2 °. If it is ± 0.2 ° or more, there is a concern that the shape may be distorted due to the influence of the anisotropy of the collimation half angle particularly when patterning a complicated shape.

  Although the reflection method using the concave mirror 6 is used, a transmission method using a convex lens may be adopted. The reflection lens is used to allow parallel light to enter the exposure irradiation surface 7 and may be omitted depending on the layout.

  The gap between the photomask 12 and the substrate has a mechanism that is automatically adjusted by a sensor, but the set value of the gap is preferably about 100 μm. This is because when a foreign object exists between the photomask 12 and the substrate, the mask is damaged if the gap is narrow.

  The exposure light 3 reflected by the reflecting mirror 8 is once returned to the condensing mirror 2 and irradiated again to the fly-eye lens unit 5. At this time, the optical design is such that light is incident on the inner side of the installation area of the reflecting mirror 8.

  As a result, the exposure light 3 that has conventionally been lost in the light shielding plate 9 can be effectively utilized without being lost, and the reduction in illuminance can be compensated.

An exposure light source (mercury lamp), leaving 12 central parts (3 horizontally and 4 vertically) of the fly-eye lens unit 5 composed of 56 (7 horizontally, 8 vertically) element lenses 13 A reflection mirror 8 on which silver is deposited on one side and a light shielding plate 9 on the exposure irradiation surface 7 side are used.

<Comparative Example 1>
The fly-eye lens unit 5 composed of 56 (7 horizontally, 8 vertically) element lenses 13 was used as it was.

<Comparative example 2>
The fly-eye lens unit 5 comprising 56 (7 horizontally, 8 vertically) element lenses 13 leaves 12 central portions (3 horizontally and 4 vertically) on the exposure irradiation surface 7 side. What provided the light-shielding plate 9 was used.

  Table 1 summarizes the results relating to the illuminance of Example 1, Comparative Example 1, and Comparative Example 2.

Table 2 shows a summary of line width characteristic values in Example 1, Comparative Example 1, and Comparative Example 2.

FIG. 8 shows the relationship between the line width (μm) and the optical intensity in Example 1 and Comparative Example 2 where the collimation half angle is 1.0 deg and Comparative Example 1 where the collimation half angle is 2.0 deg. It can be seen that the light spread through the photomask 12 can be suppressed by setting the half angle to 1.0 deg.

  The fly-eye lens unit 5 including the 56 element lenses 13 of Comparative Example 1 has a collimation half angle of 2.0 deg and an illuminance as high as 44,7 mW, but the difference in line width variation is as large as 1.9 μm. Oops. In Comparative Example 2, the collimation half angle was improved to 1.0 deg and the difference in line width variation was improved to 0.7 μm. However, the illuminance decreased to 9.7 mW (about 21%), and the exposure time was reduced. It has become about 5 times. In Example 0, the illuminance reduction at a collimation half angle of 1.0 deg was improved, the difference in line width variation was improved to 0.7 μm, and the illuminance was 34.2 mW, which is about one third of that in Comparative Example 2. The exposure time was improved.

1 ... Exposure light source (mercury lamp)
2 ... Condenser mirror 3 ... Exposure light 4 ... Plane mirror 5 ... Fly eye lens unit (integrator lens)
6 ... concave mirror 7 ... exposure irradiation surface 8 ... reflecting mirror 9 ... light shielding plate 10 ... reflected light 11 ... exposure light 12 that has passed through the fly-eye lens unit ... photo mask 13 ... Element lens 14 ... Collimation half-width

Claims (5)

A proximity exposure apparatus that exposes exposure light through a concave mirror by bringing a photomask having a predetermined pattern close to a substrate coated with a photosensitive resin, passing through a condensing mirror, and passing through a fly-eye lens. And
A reflection mirror for returning to the condenser mirror is provided on the light incident surface side of the fly eye lens peripheral portion, and a collimation half-angle adjusting light shielding layer is provided on the light passage surface side of the portion where the reflection mirror is provided. A color filter exposure apparatus.   The color filter exposure apparatus according to claim 1, wherein the collimation half angle is 0.5 deg to 1.7 deg.   The reflection mirror is attached at an angle of 90 degrees or less with respect to an irradiation optical axis in order to return exposure light including ultraviolet light and visible light irradiated to the light shielding layer to the condenser mirror. The color filter exposure apparatus according to claim 1 or 2.   The color filter exposure apparatus according to claim 1, wherein an Al vapor deposition film is provided on a surface of the reflecting mirror.   A color filter manufacturing method manufactured using the color filter exposure apparatus according to claim 1.