CN112055831A

CN112055831A - Light irradiation device

Info

Publication number: CN112055831A
Application number: CN201980026975.2A
Authority: CN
Inventors: 吉田祐治; 池田聪; 新井敏成
Original assignee: V Technology Co Ltd
Current assignee: V Technology Co Ltd
Priority date: 2018-06-08
Filing date: 2019-06-07
Publication date: 2020-12-08
Also published as: TW202001382A; JP2019211725A; KR20210016510A; WO2019235629A1

Abstract

The invention provides a light irradiation device for irradiating scattered light to an exposed surface, which can irradiate light with proper wavelength according to the wavelength dependence of a photosensitive material. The light irradiation device is provided with: a light source unit that emits scattered light toward an exposed surface; and an optical filter that transmits the light emitted from the light source unit, wherein the light source unit emits light in a short-wavelength-side band in which a selected wavelength set in the optical filter is cut.

Description

Light irradiation device

Technical Field

The present invention relates to a light irradiation device for irradiating a photosensitive material with light having a specific wavelength.

Background

A light irradiation device for exposing a photosensitive material to light is known to include a light irradiation device for irradiating parallel light and a light irradiation device for irradiating scattered light, depending on the type of light source or the optical system. A light irradiation device for irradiating parallel light requires an optical system such as a light source for emitting light with high directivity, a collimator lens, or a collimator mirror, and has a problem of high cost and large size. The light irradiation device for irradiating scattered light is relatively inexpensive and can be miniaturized.

In a light irradiation device for obtaining a photo-alignment film of a liquid crystal panel, a large light irradiation area is required as the liquid crystal panel is increased in size, and therefore, a scattering light source such as a long-arc mercury lamp or a metal halide lamp is used to irradiate a scattering light to an exposure surface. Such a light irradiation device includes a lamp housed inside an elliptical mirror, an optical filter for transmitting light having a wavelength of 320 to 450nm is disposed at a light exit of the elliptical mirror, and a polarizing mirror such as a wire grid for polarizing the light transmitted through the optical filter is disposed (see patent document 1 below).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2017-53910

Disclosure of Invention

Technical problem to be solved by the invention

In exposure of a photo-alignment film or the like, it is sometimes necessary to set the wavelength of light to be irradiated in an appropriate range depending on the wavelength dependence of the photosensitive material. In this case, as the optical filter used in the light irradiation device, a band-pass filter is used in which the wavelength of the transmitted light is specified to a relatively narrow band.

In the light irradiation device that irradiates the exposure surface with the scattered light, the directions of light transmitted through the band pass filter are various. The band-pass filter can obtain a selected wavelength at which the direction of transmitted light is set with respect to light parallel to the thickness direction, and has a characteristic that the selected wavelength shifts to the short wavelength side with respect to light transmitted obliquely with respect to the thickness direction.

Therefore, even when the selection wavelength of the band pass filter is appropriately set according to the wavelength dependency of the photosensitive material, most of the transmitted light is transmitted obliquely to the thickness direction of the band pass filter when the scattered light is irradiated, and therefore the selection wavelength of the transmitted light is shifted to the shorter wavelength side than the set wavelength, and an appropriate exposure state cannot be obtained.

The present invention has been made to solve such problems. That is, the subject of the present invention is to provide a light irradiation device for irradiating a light irradiation surface with scattered light, which can irradiate light of an appropriate wavelength according to the wavelength dependence of a photosensitive material.

Means for solving the technical problem

In order to solve the above problem, the present invention has the following configuration.

A light irradiation device is characterized by comprising: a light source unit that emits scattered light toward an exposed surface; and an optical filter that transmits light emitted from the light source unit, wherein the light source unit emits light in a short-wavelength-side band in which a selected wavelength set in the optical filter is cut off.

Drawings

Fig. 1 is an explanatory view showing a conventional light irradiation device ((a) is a side view and (b) is a front view of a lamp).

Fig. 2 is an explanatory diagram showing the wavelength selection characteristics of the optical filter.

Fig. 3 is an explanatory view showing a light irradiation device according to an embodiment of the present invention ((a) is a side view and (b) is a front view of a lamp).

Fig. 4 (a) is a diagram showing the wavelength selection characteristic of the optical filter, (b) is a diagram showing the wavelength characteristic of light emitted from the light source unit, and (c) is a diagram showing the wavelength characteristic of light transmitted through the optical filter.

Fig. 5 is an explanatory view showing an example of use of the light irradiation device according to the embodiment of the present invention.

Fig. 6 is an explanatory diagram showing another use example of the light irradiation device according to the embodiment of the present invention.

Detailed Description

Hereinafter, the present invention is explained with reference to drawings (in the following drawings, an arrow X direction indicates a scanning direction, an arrow Y direction and a Z direction are orthogonal to each other and indicate a direction orthogonal to the arrow X direction).

Fig. 1 shows a conventional light irradiation device. The light irradiation device J1 includes a reflector J2, a lamp J3, an optical filter J4, and a polarizer (e.g., a wire grid) J5. The lamp J3 is a long-arc mercury lamp or the like, is a long lamp extending in a direction (the illustrated Y direction) intersecting the scanning direction (the illustrated X direction), and emits scattered light. The reflector J2 has an elliptical reflecting surface that accommodates the lamp J3, and reflects light emitted from the lamp J3 and emits the light toward an exposure surface, which is not shown.

In the light irradiation device J1, light directly emitted from the lamp J3 toward the exposed surface and light reflected by the reflector J2 and emitted toward the exposed surface transmit the optical filter J4 at various angles. In particular, as shown in fig. 1 (b), light emitted in a plane along the longitudinal direction of the lamp J3 is not restricted in the reflection direction by the reflector J2, and therefore passes through the optical filter J4 at an emission angle of scattered light emitted from the lamp J3.

At this time, the wavelength selective characteristic of the optical filter J4 becomes the selective wavelength shown in a of fig. 2 with respect to the light parallel to the thickness direction of the optical filter J4, but the selective wavelength shifts to the shorter wavelength side with respect to the light obliquely transmitting through the optical filter J4 as shown in b of fig. 2 according to the angle thereof. Therefore, assuming that the wavelength band of the light emitted from the lamp J3 is a band including λ 1, λ 2, and λ 3, the wavelengths of the light transmitted in the thickness direction of the optical filter J4 are selected to be λ 2 and λ 3, and the wavelength of the light obliquely transmitted through the optical filter J4 is a wavelength band including λ 1, λ 2, and λ 3, and the light is transmitted at the wavelength λ 1 on the short wavelength side shorter than the selected wavelength set in the optical filter J4.

According to such a conventional example, although light in wavelength bands of λ 2 and λ 3, which are the selective wavelengths of the optical filter J4, is originally irradiated to the exposure target surface, most of the light irradiated to the exposure target surface is in the wavelength bands of λ 1, λ 2, and λ 3, and a large amount of light having a short wavelength shorter than the set selective wavelength is irradiated, so that an overexposure state is caused, and a problem arises in that an appropriate exposure state cannot be obtained.

The light irradiation device 1 according to the embodiment of the present invention shown in fig. 3 includes a light source unit 2, an optical filter 3, and a polarizer (wire grid, etc.) 4. In the example shown in the figure, the exposed surface is the treated surface of the photo-alignment film, and the polarizer 4 is provided to polarize the light transmitted through the optical filter 3, but in the case of an exposure apparatus used for another purpose, the polarizer 4 can be omitted as appropriate.

In the light irradiation apparatus 1, the light source unit 2 emits scattered light toward the surface to be exposed, and the light emitted from the light source unit 2 passes through the optical filter 3 and is irradiated with light of a specific wavelength. Here, the wavelength selective characteristic of the optical filter 3 is similar to the above-described conventional technique, and the selected wavelength is shifted to the shorter wavelength side as shown by a graph a in fig. 4 (a) with respect to the light parallel to the thickness direction of the optical filter 3, and the selected wavelength is shifted to the shorter wavelength side as shown by a graph b in fig. 4 (a) with respect to the light obliquely transmitting the optical filter 3.

On the other hand, as shown in fig. 4 (b), the light source section 2 emits light in a short-wavelength side band in which the selected wavelengths λ 2 and λ 3 set in the optical filter 3 are cut off. Therefore, the wavelength band of the light emitted from the light source unit 2 does not include the light of the wavelength λ 1, and even if the wavelength selection characteristic of the optical filter 3 shifts to the shorter wavelength side with respect to the light obliquely passing through the optical filter 3, the wavelengths of all the lights passing through the optical filter 3 are selected to be λ 2 and λ 3 as shown in fig. 4 (c), and therefore, the problem of excessive exposure as in the conventional technique does not occur.

In the embodiment shown in fig. 3, the light source unit 2 of the light irradiation device 1 includes a reflector 2A having an elliptical reflecting surface and a lamp 2B housed in the reflector 2A, as in the conventional art. The lamp 2B is a long-arc mercury lamp or the like, and is a long lamp extending in a direction (illustrated Y direction) intersecting the scanning direction (illustrated X direction). The lamp 2B is provided with a coating layer 2C of a wavelength selective base material that cuts off a band on the shorter wavelength side of the selected wavelength of the optical filter 3.

The coating layer 2C has a two-layer structure including a zirconium oxide film formed as a 1 st layer and a silicon oxide film formed as a 2 nd layer on the outer surface of the lamp, and has a light transmittance of 2% or less in a wavelength region of 200nm or less, 75% to 95% or less in a wavelength region of 254nm, and 50% in a wavelength region of 220 to 235 nm. The thickness of the zirconia film is appropriately selected, but too thin increases the transmittance of light on the short wavelength side, whereas too thick decreases the transmittance of light of 254nm, and therefore, the thickness is preferably in the range of 30 to 80 nm. The thickness of the silicon oxide film is also preferably about 10 to 30 nm.

By providing such a coating layer 2C, the light source section 2 emits light with a wavelength λ 1 cut off at a short wavelength side shorter than the selected wavelength of the optical filter 3. In the embodiment shown in fig. 3, the coating layer 2C is provided only on the lamp 2B, but a coating layer that absorbs the wavelength λ 1, for example, may be provided on the reflecting surface of the reflector 2A in addition to the coating layer 2C provided on the lamp 2B.

Fig. 5 and 6 show an example of use of the light irradiation device 1. In the example shown in fig. 5, when the exposure is performed on the workpiece W having the surface to be exposed while moving the light source section 2 in the X direction shown in the drawing, the light source section 2 is constituted by 1 long lamp and is provided to extend in the direction (Y direction shown in the drawing) intersecting the scanning direction. In the example shown in fig. 6, the lamps of the light source unit 2 are short lamps extending in the same direction as the scanning direction (X direction in the figure), and a plurality of the lamps are arranged in a direction intersecting the scanning direction.

In the examples shown in fig. 5 and 6, the light irradiation device 1 in either example irradiates the exposure surface of the workpiece W with diffused light, but the wavelength of light irradiated to the exposure surface is the wavelength selected by the optical filter 3, and the problem of overexposure as in the conventional technique can be avoided.

As described above, the light irradiation device 1 according to the embodiment of the present invention can set the wavelengths of all the lights transmitted through the optical filter 3 to the set selected wavelengths when the scattered lights are irradiated to the surface to be exposed. This makes it possible to expose the photosensitive material to light of an appropriate wavelength according to the wavelength dependence of the photosensitive material to be exposed. In particular, in the exposure of the photo-alignment film, unevenness in the exposure wavelength can be suppressed, and a high-quality photo-alignment film can be obtained.

Description of the symbols

1-light irradiation device, 2-light source section, 2A-reflector, 2B-lamp, 2C-coating layer, 3-optical filter, 4-polarizer (wire grid), W-workpiece.

Claims

1. A light irradiation device is characterized by comprising:

a light source unit that emits scattered light toward an exposed surface; and an optical filter for transmitting the light emitted from the light source,

the light source unit emits light in a short wavelength side band in which a selected wavelength set in the optical filter is cut off.

2. The light irradiation apparatus according to claim 1,

the light source unit includes: a lamp that emits scattered light; and a reflector for reflecting the light emitted from the lamp toward the exposed surface,

the lamp is coated with a wavelength-selective substrate in a band on the short wavelength side of which the selected wavelength is cut off.

3. The light irradiation apparatus according to claim 2,

the lamps are long lamps extending in the direction crossing the scanning direction.

4. The light irradiation apparatus according to claim 2,

the lamps are short lamps extending in the same direction as the scanning direction, and are arranged in a plurality of directions intersecting the scanning direction.

5. The light irradiation device according to claim 1, comprising:

a polarizer for polarizing light transmitted through the optical filter,

the exposed surface is a processed surface of the photo-alignment film.