JP7257100B2 - Transparent substrate, thin film supporting substrate - Google Patents

Description

The present invention relates to a transparent substrate and a thin film support substrate obtained by laminating a thin film on a transparent substrate.

A transparent substrate that transmits light is used as a light extraction side substrate of a self-luminous element such as an organic EL element. As for such a transparent substrate, there is known one in which unevenness is formed on the surface for the purpose of improving light extraction efficiency (see Patent Document 1 below).

JP 2004-127746 A

The transparent substrate described above is patterned with a transparent electrode layer, an insulating layer, and the like on the surface thereof using a photolithography process. In that case, after forming a thin film to be patterned on a transparent substrate, a photoresist is applied thereon, and mask exposure with ultraviolet light is performed. In mask exposure, the ultraviolet rays passing through the opening of the photomask pass through the photoresist layer and thin film, and are reflected back at the interface of the transparent substrate. In the case of shaping, the photoresist layer under the light-shielding region of the photomask is exposed to ultraviolet rays reflected in various directions at the interfaces of the uneven shaping.

In this way, a transparent substrate on which a pattern is formed by a photolithography process on its surface is provided with irregularities on its front or back surface. There is a problem that edge blurring of the pattern occurs due to exposure of the layer.

An object of the present invention is to address such problems. That is, it is an object of the present invention to prevent blurring of the edges of a pattern when patterning a thin film laminated on a transparent substrate having unevenness on its front or back surface by a photolithography process. .

In order to solve such problems, the present invention has the following configurations.
A step of preparing a transparent substrate having an ultraviolet transmittance of 50% or less, and a step of forming unevenness on one or both of the front surface and the back surface simultaneously with or after the step of preparing the transparent substrate on the transparent substrate. , the uneven shaping reflects the ultraviolet rays in various directions at the interface, and then photolithography is performed using the ultraviolet rays to form a pattern to form a thin film supporting substrate ; A method for manufacturing a thin film laminated substrate having the patterned thin film supporting substrate, comprising the step of laminating a thin film including an electrode layer on a supporting substrate.

In the present invention having such characteristics, the ultraviolet rays passing through the openings of the photomask become difficult to transmit through the transparent substrate after exposing the photoresist layer, so that the ultraviolet rays are reflected at the interface of the transparent substrate having irregularities and are again reflected. Ultraviolet radiation that exposes the photoresist layer is suppressed. As a result, blurring of pattern edges can be suppressed, and a patterning layer with high dimensional accuracy can be formed on a transparent substrate having irregularities.

It is explanatory drawing which showed the state of the mask exposure in the photolithography process ((a) shows a comparative example, (b) has shown the transparent substrate of this invention.). 1 is a graph showing light transmittance for each wavelength in an example (substrate thickness: 1 mm) in which silicate glass containing cerium oxide is used as a transparent substrate ((a) is transmittance in a wide band including the visible range; ( b) is the transmittance in the ultraviolet region). 1 is a graph showing the transmittance for each wavelength of an example (substrate thickness 1 mm) in which soda lime glass containing vanadium oxide is used as a transparent substrate ((a) is the transmittance in a wide band including the visible range, (b) is the transmittance in the ultraviolet region). FIG. 2 is an explanatory diagram showing an organic EL element substrate as an example of a thin film supporting substrate in which a thin film is laminated on a transparent substrate;

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, when a photoresist layer R on a thin film (such as an ITO film) T formed on a transparent substrate G having irregularities is irradiated with ultraviolet UV through a photomask M, As shown in (a), when there is an ultraviolet ray UV that is reflected back at the interface of the uneven shaping, the ultraviolet ray UV is reflected in various directions at the interface of the uneven shaping. The reflected ultraviolet light UV will expose the light shielded areas of the photoresist layer R, which will result in edge blurring of the pattern.

On the other hand, when the transparent substrate G1 is a substrate having a low transmittance of ultraviolet rays (for example, 365 nm) used in the photolithography process, as shown in FIG. The passed ultraviolet rays UV expose the photoresist layer R and after passing through the thin film T on the transparent substrate G1, most of the ultraviolet rays UV are absorbed by the transparent substrate G1. As a result, the ultraviolet rays that are reflected at the unevenly shaped interface of the transparent substrate G1 to expose the photoresist layer R again are suppressed, and the photoresist layer R is exposed according to the opening pattern of the photomask M. As a result, in the subsequent development process of the photoresist layer R and the etching process of the thin film T, highly accurate pattern formation corresponding to the mask pattern becomes possible.

In FIG. 1(b), the transparent substrate G1 is formed with unevenness on only one side, but has unevenness-enhanced surfaces on both sides, and a thin film T is formed on the unevenness-enhanced surfaces. It may be a film-coated one. Alternatively, the thin film T may be formed on the uneven surface formed on only one surface of the transparent substrate G1. Also, in FIG. 1(b), the thin film T on the transparent substrate G1 is only one layer, but a multilayer thin film T may be laminated and a pattern may be formed on one of them. An example of the thin film T here is a transparent electrode layer, an insulating layer, or the like of a self-luminous element having a thin film lamination structure.

The relationship between the transmittance of ultraviolet rays in the transparent substrate G1 and the rate of light returning at the interface (return rate) is as follows. 1. As is clear from Table 1, by setting the transmittance to 50% or less, the return rate can be greatly reduced (to 25% or less), and by setting the transmittance to 30% or less, the return rate can be further reduced. It becomes possible to lower it (single digit % or less). In this way, by keeping the ultraviolet transmittance of the transparent substrate G1 low, it is possible to effectively suppress the ultraviolet rays that are reflected at the interfaces of the uneven shapes of the transparent substrate G1 and expose the photoresist layer R again.

When the transparent substrate G1 is a glass substrate, it is possible to reduce the transmittance of ultraviolet rays to a desired rate by making the glass substrate contain an ultraviolet absorbing component. At this time, when the transparent substrate G1 is the light extraction side substrate of the light emitting device for illumination, the material and content of the ultraviolet absorbing component are determined so that the light transmittance in the visible light region does not decrease due to the inclusion of the ultraviolet absorbing component. is desired to be selected as appropriate.

When the transparent substrate G1 is a glass substrate and is the light extraction side substrate of the light emitting device for illumination, cerium oxide (CeO ₂ ) and vanadium oxide (V ₂ O ₅ ) are exemplified as suitable ultraviolet absorbing components. can do.

FIG. 2 shows the light transmittance for each wavelength in an example of using silicate glass containing cerium oxide as a glass substrate (substrate thickness: 1 mm). Here, the light transmittance of 0% cerium oxide silicate glass, 0.24% cerium oxide silicate glass, and 0.47% cerium oxide silicate glass is shown. Silicate glass containing 0.24% by weight of cerium oxide suppresses the transmittance of ultraviolet light with a wavelength of 365 nm to about 50%, and the transmittance of visible light region (wavelength of 400 nm or more) to about 80% or more. In addition, the silicate glass containing 0.47% by weight of cerium oxide suppresses the transmittance of ultraviolet light with a wavelength of 365 nm to about 30%, and the transmittance of the visible light region (wavelength of 400 nm or more) to about 70% or more. .

FIG. 3 shows the light transmittance for each wavelength of an example in which soda-lime glass containing vanadium oxide is used as a glass substrate (substrate thickness: 1 mm). Here, the light transmittance of soda-lime glass with 0% vanadium oxide, soda-lime glass with 0.2% by weight vanadium oxide, and soda-lime glass with 0.5% by weight vanadium oxide is shown. The soda-lime glass containing 0.2% by weight of vanadium oxide suppresses the transmittance of ultraviolet light with a wavelength of 365 nm to about 57%, and the transmittance of the visible light region (wavelength of 400 nm or more) to about 87% or more. Also, the soda-lime glass containing 0.5% by weight of vanadium oxide suppresses the transmittance of ultraviolet light with a wavelength of 365 nm to about 30%, and the transmittance of the visible light region (wavelength of 400 nm or more) to about 81% or more.

As is clear from the examples of FIGS. 2 and 3, in the glass substrate containing cerium oxide or vanadium oxide, the content of cerium oxide or vanadium oxide is set to 0.2 to 0.5% by weight, and the effect is It can absorb ultraviolet light effectively and transmit visible light with high transmittance.

FIG. 4 shows an organic EL element substrate as an example of a thin film supporting substrate in which a thin film is laminated on a glass substrate. The organic EL element substrate 1 is a part of the light source of a light emitting device for illumination, and includes a glass substrate 2. On the glass substrate 2, a transparent electrode layer (anode layer) 3, an insulating layer 4, and a light emitting functional layer 5 are formed. , a metal electrode layer (cathode layer) 6 and other thin films are laminated. The glass substrate 2 is a substrate on the light extraction side, and light is extracted to the outside through the glass substrate 2 .

Since the glass substrate 2 contains an ultraviolet absorbing component, it is possible to accurately pattern the transparent electrode layer 3 and the insulating layer 4, which are pattern forming layers, using a photolithography process.

Table 2 below shows the transmittance of the cerium oxide (CeO ₂ ) content of the glass substrate 2 at a wavelength of 365 nm and visible light. Example 1 is a comparative example that does not contain cerium oxide (CeO ₂ ), which is an ultraviolet absorbing component _. This is an example in which the content is changed up to 31% by weight.

By increasing the content of CeO ₂ as a glass component in Examples 2 to 5, it is possible to suppress the transmittance of ultraviolet rays (wavelength: 365 nm). become. In order to secure the transmittance in the visible light region, it is preferable to set the content of CeO ₂ to 0.2 to 0.5% by weight, as described above.

Since the glass substrate 2 contains an ultraviolet absorbing component, pattern formation of the transparent electrode layer 3 and the insulating layer 4 can be performed with high accuracy. As a result, it is possible to realize a high-quality lighting device with less light emission unevenness.

1: organic EL element substrate, 2: glass substrate, 3: transparent electrode layer,
4: insulating layer, 5: light-emitting functional layer, 6: metal electrode layer

Claims (3)

A step of preparing a transparent substrate having an ultraviolet transmittance of 50% or less;
Simultaneously with or after the step of preparing the transparent substrate, the transparent substrate has a step of forming unevenness on one or both of the front surface and the back surface, and the unevenness shaping is performed by irradiating the ultraviolet rays at the interface. direction and then
A step of photolithography using the ultraviolet rays to form a pattern to form a thin film supporting substrate;
laminating a thin film including an electrode layer on the thin film supporting substrate;
A method of manufacturing a thin film laminated substrate having the patterned thin film support substrate comprising:
2. The method of manufacturing a thin film laminated substrate having the patterned thin film supporting substrate according to claim 1 , wherein the transparent substrate contains an ultraviolet absorbing component.
3. The method of manufacturing a thin film laminated substrate having the patterned thin film supporting substrate according to claim 2 , wherein the ultraviolet absorbing component is cerium oxide or vanadium oxide.

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