JP5221066B2 - Film laminated substrate, counter substrate for liquid crystal panel and liquid crystal panel - Google Patents

Description

  The present invention relates to a film laminated substrate, a counter substrate for a liquid crystal panel, and a liquid crystal panel.

  2. Description of the Related Art Conventionally, a film laminated substrate in which a plurality of thin films are laminated on at least one surface of a flat substrate has been widely known as a polarizing plate, an antireflection filter, or the like. In addition, as a counter substrate for a liquid crystal panel, a “micro lens array corresponding to a liquid crystal pixel array” is formed on one side of a flat substrate, and each pixel of a black matrix for blocking illumination light by the formed micro lens array It is known to increase the light utilization efficiency by condensing light on a part.

  Of the thin films stacked on these film laminated substrates, many of them generate stress in the film surface direction (direction along the film surface) during the film formation process.

  On the other hand, “thinning” of a flat substrate on which films are laminated is progressing, and “warping” easily occurs due to the stress exerted on the formed thin film. When the film laminated substrate is warped, the “original function of the film laminated substrate” is impaired.

  As a measure for correcting such warpage of the substrate, a thin film that expresses tensile stress is formed on the substrate surface opposite to the side on which the film is laminated, and the tensile stress due to the film on the front and back of the substrate is offset, A method for ensuring flatness has been proposed (Patent Document 1).

  Recently, the use of “sol-gel materials” as membrane materials is contemplated. The sol-gel material is an inorganic material and can form a firm thin film, and thus has excellent environmental resistance. That is, when the siloxane bond of the sol-gel material is completely formed during the film formation process, a “three-dimensional skeleton structure made of silica glass” is obtained. This state is a “cured state (cured layer)”, which is a chemically stable and extremely strong structure. In addition, since the refractive index can be adjusted by the composition of the material, there is an advantage that a “thin film that can be used optically” having a desired refractive index can be easily obtained.

However, a sol-gel material thin film tends to generate “strong tensile stress” during the film formation process. This is because during film formation, a dehydration reaction occurs in the process of forming a three-dimensional skeleton structure made of silica glass, and the film shrinks. This problem is a general phenomenon when not only a sol-gel material but also a “polycondensation material having a SiO ₂ skeleton” is formed. Examples of the “polycondensation material having SiO ₂ skeleton” include HSQ and silsesquioxane in addition to the sol-gel material.

When such a thin film of “polycondensation material having SiO ₂ as a skeleton” is formed on a flat substrate, the substrate is warped by the action of the tensile stress as described above.
When trying to correct such “warp” by the method described in Patent Document 1, if the surface of the thin film is a free surface, cracks (cracks in the polycondensation material thin film having a SiO ₂ skeleton) accompany the correction. ) May occur. In addition, the method described in Patent Document 1 needs to form films on the front and back of a flat substrate, and the process of forming a film on the front side and the process of forming a film on the back side are completely separate processes. After the film formation, a process of turning the substrate upside down and forming the film on the other surface is required, and the number of film formation processes increases.

Japanese Patent Laid-Open No. 11-153788

  In view of the above, the present invention has an object to realize a novel film laminated substrate that effectively solves the “problem of warping” of a flat substrate and a counter substrate / liquid crystal panel for a liquid crystal panel using the film laminated substrate. To do.

The film laminated substrate of the present invention is “a film laminated substrate formed by laminating and forming N (4 ≧ N ≧ 2) thin films on at least one surface of a flat substrate”, and has the following characteristics. 1).
That is, a thin film pair consisting of “a thin film obtained by firing a silica-based sol-gel material that shrinks in the film surface direction during film formation” and “a thin film of SiO ₂ that extends in the film surface direction during film formation” on at least one surface of a flat substrate. Are formed in M pairs (1 ≦ M ≦ N / 2) .
The “SiO ₂ thin film” is formed by sputtering.
And in each thin film pair of a thin film that shrinks in the film surface direction during film formation (thin film obtained by firing a silica-based sol-gel material) and a thin film that extends in the film surface direction during film formation (a thin film of SiO ₂ by sputtering ) The film thickness after firing of the thin film that shrinks in the film surface direction during film formation: d1, and the film thickness of the thin film that extends in the film surface direction during film formation: d2
d2 = (1 / 4.5) d1
Satisfied.
As a result, the “film thickness of each M pair of thin films” is set so that the stress in the film surface direction is canceled out and the stress that causes warping of the substrate does not act on the entire N layer thin film formed on one side. ing.
The “stress in the film surface direction” is a stress acting along the surface direction of the film, and exerts a force that bends the substrate. In the film laminated substrate of the present invention, as described above, “M pairs of thin films are laminated on at least one surface of the substrate”, but the stress in the film surface direction is reduced as the entire N layer thin film formed on one surface. Offset.

For example, if the number of N thin films is N = 2 (the number of thin film pairs: M = 1) , the stress in the film surface direction is offset in the two thin films formed on one side of the substrate. The That is, if one thin film generates “tensile stress”, the other thin film generates “extension stress (stress that tends to extend in the direction of the film surface)” and cancels the tensile stress with the tensile stress. .

  In this case, for example, when the first layer thin film directly formed on the substrate generates a tensile stress, the second layer thin film formed on the first layer generates a tensile stress. Extends the “shrinkage due to tensile stress”. Then, as a whole of the two-layer film, the stress in the film surface direction is offset so that “the stress causing the warp to the substrate does not act”.

This can be done by adjusting the “material and film thickness of the first layer film” and the “material and film thickness of the second layer film”.
That is, supplementing the explanation for the case where the film formed on one side of the substrate is two layers, the stress in the substrate surface direction acting on the substrate surface (film formation surface) when the two layers of films are laminated is formed. F, if the stress in the film surface direction of the first layer is F1, and the stress in the film surface direction of the second layer is F2, between F, F1 and F2,
F = F1 + F2 (1)
The relationship became.

On the other hand, the stress in the film surface direction: F1 of the film of the first layer is proportional to the thickness of the first layer: D1,
F1 = a · D1 (2)
The stress in the film surface direction: F2 of the film of the second layer is proportional to the thickness of the second layer: D2,
F2 = b · D2 (3)
It is expressed. Proportional constants: a and b are determined by “film material”.

Further, the amount of warpage of the substrate due to stress: F1, F2: C1, C2 is proportional to the magnitude of the stress: F1, F2, and the proportionality constant: α determined by the substrate is used.
C1 = αF1 = αaD1 (4)
C2 = αF2 = αbD2 (5)
Given in.

Therefore, the condition that the warpage amount C1 due to the stress F1 is offset by the warpage amount C2 due to the stress F2 is:
C1 + C2 = 0 (6)
(4) and (5),
αaD1 + αbD2 = 0 (7)
Should just hold.

  At this time, since aD1 = −bD2, F1 = −F2, and the stress in the substrate surface direction acting on the substrate surface (film formation surface) is “F = F1 + F2 = 0”.

Condition: aD1 = −bD2
From the thickness of the first layer: D1, the thickness of the second layer: D2,
D2 = − (a / b) D1 (8)
If the setting is made, “substrate warpage” does not occur. Warpage amount: Since C1 and C2 have opposite signs, a and b are also opposite signs, and “− (a / b) D1” is a positive amount.

In the condition (8) in which no warp occurs, the proportionality constants: a and b are determined by the film materials of the first layer and the second layer, respectively, so the material and film thickness of the first layer and the second layer and the film thickness: D1, By selecting D2 so as to satisfy the equation (8), it is possible to prevent the substrate from being bent (warped).
According to claim 1, one of the thin film pairs of M (N / 2 ≧ M ≧ 1) pairs is “a thin film that contracts in the film surface direction during film formation (a thin film obtained by firing a silica-based sol-gel material). The other is “a thin film that stretches in the film surface direction during film formation (SiO ₂ thin film by sputtering )”, and the film thickness after firing of the thin film that contracts in the film surface direction during film formation: d1 is the above “D1” in Expression (8), and the film thickness d2 of the thin film extending in the film surface direction during film formation is “D2” in Expression (8) above, and the constant in Expression (8) above:
(A / b) is “(1 / 4.5)”.
When the N-layer thin film is formed of two thin film pairs as in Example 2 to be described later, the film thicknesses d1 and d2 in each thin film pair may be different for each “thin film pair”. .

  If the stress in the film surface direction acting on the first layer film is a tensile force, the film of the first layer receives from the film of the second layer “a force to extend the contraction of the first layer in the film surface direction. However, since the second layer is in close contact with the film surface of the first layer, the occurrence of cracks in the film of the first layer is effectively prevented.

The case where two layers of films are stacked on the substrate has been described above, but the above description can be applied to the case where the number of thin films is increased to three or more.
That is, the number of layers of thin films: N is the number of thin film pairs: greater than 2M against M, while the thin films of N layers, it is one that does not constitute the thin film pairs, constituting the case "thin film pairs The “non-thin film” is a layer that does not generate stress during film formation (claim 2).
When three layers of films are laminated on one side of the substrate , as described in claim 2 above , tensile stress is generated in one of the three layers, tensile stress is generated in the other layer, and the rest One layer may be “a film in which stress is not particularly generated” .
The “layer that does not generate stress during film formation” is, for example, the above-mentioned “thin film obtained by firing a silica-based sol-gel material” or “a thin film of SiO ₂ by sputtering”. In the case where no stress of a “size that warps” is generated, it can be a “layer that does not generate stress during film formation”.

In the case of forming an even-numbered layer (N = 2 or 4) film, a layer as a whole layered film is formed by alternately laminating a layer generating tensile stress and a layer generating tensile stress. The stress in the surface direction can be canceled out.

  The number of thin films laminated on one side of the substrate: The lower limit of N is 2, but the upper limit is not particularly limited, and the number of layers usually laminated (for example, tens to hundreds) is possible.

As described in claim 1, the N-layer thin film is formed on “at least one surface of a flat substrate”. The other surface of the substrate may or may not be formed. When a film is formed on the other surface, if the film to be formed is a film that “does not generate stress in the film surface direction”, the substrate as a whole will not be bent (warped). Further, as described above, the “film that generates tensile stress” and the “film that generates extensional stress” are combined in the same manner as in the above-described one side surface to cancel the stress in the film surface direction as a whole. It is only necessary to prevent the stress in the substrate surface direction from being generated on both sides of the substrate.

  In addition, as described in claim 1, “as the whole N layer thin film formed on one side of the substrate, the stress in the direction of the film is offset and the stress causing the warp on the substrate does not act”. The stress in the film surface direction is not necessarily “necessary to cancel out the stress to be completely zero”. As a result of the cancellation, even if some tensile stress or extensional stress remains, the residual stress is “substantial to the substrate. If it does not cause “warping,” there is no problem.

In the film laminated substrate according to claim 1 , a micro optical surface can be formed on the surface of the flat substrate on the side where the N-layer thin film is formed (claim 3) .

In the film laminated substrate according to claim 3, the micro optical surface formed on the surface of the flat substrate on the side where the thin film of the N layer is formed can be, for example, a “micro lens array”. It can be “an arrangement of microlens arrays” (claim 4).

  The “opposite substrate for a liquid crystal panel” according to the present invention is an N substrate in which an “array of microlens arrays” is formed on one side of a flat substrate and the laminated substrate is formed on the flat substrate. A black matrix pattern for light shielding and a transparent electrode film corresponding to the arrangement of the microlens are formed on the thin film of the layer for each arranged microlens array, and are separated for each microlens array. It is a substrate.

  The liquid crystal panel of the present invention is “a liquid crystal panel in which a liquid crystal layer is sealed between a counter substrate for a liquid crystal panel according to claim 5 and a drive electrode substrate”.

  As described above, according to the present invention, it is possible to realize a “film laminated substrate substantially free of warpage in a substrate”, and use this film laminated substrate to provide “a counter substrate / liquid crystal panel for a good liquid crystal panel without warping”. Can be realized.

Hereinafter, specific embodiments will be described.
FIG. 1 shows an embodiment of a liquid crystal panel as an explanatory diagram. The figure shows the structure in the thickness direction of the liquid crystal panel. Reference numeral 10 denotes a microlens array substrate, reference numeral 12 denotes a film laminated structure, reference numeral 14 denotes a black matrix pattern, reference numeral 15 denotes a transparent conductive film, reference numeral 16. Is a liquid crystal, 18 is an electrode film, and 20 is a substrate.

  The microlens array substrate 10 has a parallel plate shape, and microlenses ML are formed in an array on one side (upper surface in the drawing). The array arrangement of the microlenses ML corresponds to the array of pixels in the liquid crystal panel.

  On the surface of the microlens array substrate 10 on which the microlens array is formed, the film stack structure portion 12 is formed. As will be described later, the film laminated structure portion 12 is a structure portion in which two or more thin films are laminated, and “a stress in the film surface direction is canceled and the microlens that is a substrate is eliminated as the whole laminated structure formed by lamination. The materials and film thicknesses of the plurality of thin films are set so that the stress that causes warping of the substrate 10 does not act.

That is, in this embodiment, the microlens array substrate 10 formed with the laminated structure portion 12 is a “film laminated substrate” , and the microscopic surface of the flat substrate 10 on the side where the laminated structure portion 12 is formed is microscopic. A microlens array is formed as an optical surface .

  A light blocking black matrix pattern 14 for preventing crosstalk between pixels is formed on the surface portion of the multilayer structure portion 12, and a transparent conductive film 15 is further formed thereon. The transparent electrode film 15 is formed as a film having a single structure so as to cover the black matrix pattern 14 as a whole. The black matrix pattern 14 and the transparent conductive film 15 are conventionally known.

  The microlens array substrate 10, the laminated structure 12, the black matrix pattern 14, and the transparent conductive film 15 constitute “a counter substrate for a liquid crystal panel”.

  The electrode film 18 formed on the substrate 20 is “a two-dimensional array of TFTs that individually drive each pixel (corresponding to the array of openings of the black matrix pattern 14)” on one side of the substrate 20 ”. It is formed as. The electrode film 18 and the substrate 20 on which the electrode film 18 is formed constitute a “drive electrode substrate”. Accordingly, the liquid crystal 16 is sealed and sandwiched between the liquid crystal panel counter substrate and the drive electrode substrate. In this way, the liquid crystal 16 is sealed between the drive electrode substrate and the liquid crystal panel counter substrate to form a liquid crystal panel.

  “When a voltage is selectively applied to each TFT of the electrode film 18, an electric field acts on the liquid crystal 18 between the TFT to which the voltage is applied and the transparent electrode film 15. By modulating the voltage, the liquid crystal Can drive the panel.

  Illumination light (not shown) enters as a “linearly polarized light beam close to a parallel light beam” from the outer surface of the microlens array substrate 10 in FIG. 1 (the flat surface below in FIG. 1), and is collected by each microlens ML. The light is collected and condensed on the “opening portion of the black matrix pattern” corresponding to each microlens. In this state, by driving the liquid crystal panel as described above, a “light beam that is two-dimensionally modulated by the image information displayed on the liquid crystal panel” can be obtained. An image can be displayed by forming and projecting on a display surface such as a screen.

  Hereinafter, the counter substrate for a liquid crystal panel according to claim 5 will be described according to a specific manufacturing example.

The “opposite substrate for liquid crystal panel” of Example 1 has a configuration as shown in FIG. In order to avoid complications, the same reference numerals as those in FIG.
That is, the counter substrate for the liquid crystal panel of Example 1 is formed by laminating two thin films 121 and 122 on the surface of the microlens array substrate 10 on which the microlenses ML are arrayed as shown in FIG. The liquid layer structure (the part indicated by reference numeral 12 in FIG. 1) ”.

Such a counter substrate for a liquid crystal panel was produced as follows.
A circular quartz substrate 100 as shown in FIG. 4 was prepared. The quartz substrate 100 has a parallel plate shape with a diameter of 100 mm and a thickness of 1 mm. A large number of microlens arrays MLA were arranged in a circle having a diameter of 80 mm of the quartz substrate 100. All the microlens arrays MLA have the same structure.

The thin films 121 and 122 shown in FIG. 2 are laminated on the surface on which the microlens array MLA is formed, and the following are used as these thin films 121 and 122. That is, the “thin silica-based sol-gel material fired” as the thin film 121 and the “SIO ₂ thin film by sputtering” were used as the thin film 121.

  In order to investigate the conditions for canceling the stress in the film plane direction in these thin films, a quartz substrate 100A having the same size as the quartz substrate 100 (no microlens array is formed) is prepared as shown in FIG. Then, a “silica-based sol-gel material” having a viscosity of 15 cP was dropped on one surface in a sol state and spin-coated at a rotation speed of 1500 rpm for 30 seconds to form a liquid film 121A. This liquid film 121A was “pre-baked at 90 ° C. for 120 seconds” and then heated at 250 ° C. for 600 seconds to “fire”.

  FIG.5 (b) shows the state after baking. Reference numeral 121B denotes a “film obtained by firing”. The fired film 121B had a thickness of 4.5 μm.

  The fired sol-gel material thin film 121B is a “three-dimensional skeleton structure made of silica glass” as described above, but shrinks due to a dehydration reaction that occurs during the firing process, generates tensile stress in the film surface direction, and after firing, As shown in FIG. 5B, the warp of the quartz substrate 100A (a warp that becomes concave on the thin film 121B side due to the sintering of the sol-gel material) occurred.

  When the warpage amount: ξ in the figure was measured by an interferometer, the warpage amount: ξ = 2 with respect to the diameter: 80 mm in the circle of the quartz substrate 100A having a diameter of 80 mm (region forming the array of microlens arrays). .4 μm.

Next, as shown in FIG. 6, a SiO ₂ thin film 122B was formed on one side of a quartz substrate 100B of the same material and the same form by sputtering. The formed thin film 122B had a film thickness of 0.5 μm.

Since the SiO ₂ thin film 122B formed by sputtering expresses “extension stress” at the time of film formation, the quartz substrate 100B becomes “projected toward the thin film 122B as shown in FIG. To warp. That is, the direction of warpage of the quartz substrate 100A due to the “effect of tensile stress” of the thin film 121B due to the firing of the sol-gel material is opposite to the direction of warpage of the quartz substrate 121B due to the SiO ₂ thin film 122B formed by sputtering. .

  When the warpage amount: η of the quartz substrate 121B was measured by an interference measuring device, the warpage amount: η = 1.2 μm with respect to the diameter: 80 mm. This result will be applied to the above-described “condition for canceling the stress in the film surface direction”.

First, the amount of warpage of the fired sol-gel material by the thin film 121B:
C1 = ξ = αaD1 = αa · 4.5 = 2.4 μm,
Warpage amount due to SiO ₂ thin film 122B formed by sputtering:
C2 = η = αbD2 = αb · 0.5 = −1.2 μm
Because
a = 2.4 / 4.5α, b = −1.2 / 0.5α
And
(A / b) = (2.4 × 0.5) / (4.5 × −1.2) = − (1 / 4.5)
It becomes.

Conditions for canceling stress:
D2 = − (a / b) D1 (8)
If the film thickness of the thin film by sintering of the sol-gel material is 4.5 μm, the film thickness of the SiO ₂ thin film by sputtering is 4.5 / 4.5 = 1 μm. There is no warping of the quartz substrate.
Therefore, a “thin film by sintering of a sol-gel layer” was formed on the “surface on which the arrangement of the microlens array MLA was formed” of the quartz substrate 100 shown in FIG. 4 under the same conditions as described above. This thin film is denoted by reference numeral 121a in FIG. At this time, the thickness of the thin film 121a on the microlens array array surface was 4 μm. In order to prevent warping of the quartz substrate 100, when the SiO ₂ thin film 121b is formed to a thickness of 0.9 μm (≈4 μm / 4.5) by sputtering, the quartz substrate 100 has substantially “warping”. Did not occur.

After film formation of SiO _2, and Cr layer was 90nm deposited Cr and (chromium) by sputtering on the thin SiO ₂ film, a black matrix pattern is formed by photolithography on the Cr layer, "the resist layer by wet etching After transferring the “black matrix pattern” to the Cr layer, the resist residue was removed by washing with a “sulfuric acid / hydrogen peroxide mixture”.

Then, after forming ITO as a transparent conductive film on the patterned Cr layer to a thickness of 130 nm, the arrayed microlens arrays are separated separately, and each one is “microlens array substrate and laminated structure part” 2 having a black matrix and a transparent conductive film as shown in FIG. 2 was obtained. Each separated “opposite substrate for liquid crystal panel” had no substantial warpage.

  Here, to add a little about the point of film formation on the microlens array substrate, the significance of providing the microlens array in the microlens array substrate is that the light from the light source side is opened by the microlens as described above. By concentrating the light on the portion, the light shielding by the black matrix pattern is reduced, and the utilization efficiency of the light emitted from the light source is increased.

  The liquid crystal panel is preferably thin. From the viewpoint of thinning the liquid crystal panel, the distance between the microlens array substrate and the black matrix pattern is preferably small. To shorten this distance, the focal length of each microlens in the microlens array can be shortened. However, if the focal length is short, the light condensing by the microlens is enhanced, and the divergence of the light passing through the pixels in the liquid crystal panel is increased. Becomes larger, and it becomes difficult to make all the light effectively enter the projection lens.

  If the focal length of the microlens is increased to avoid such a problem, it is difficult to reduce the thickness of the liquid crystal panel. Therefore, as a method of ensuring the thinning of the liquid crystal panel while reducing the light condensing property by the microlens, the “focal length in the air” of the microlens is set to be small, and “ It is conceivable to “fill a material having a high refractive index”.

  Actually, a parallel light beam is incident on the microlens array and is condensed in the air at a focal length f of the microlens, and when the space between the microlens and the black matrix pattern is air or vacuum, the distance between the two However, if a material having a refractive index of N (> 1) is filled between the two, the distance between the two is compressed to 1 / N as an optical distance, so the distance between the two is D and the refractive index is N. The distance: D can be set so that DN is equal to the focal length: f. Since N> 1, D <f, and the focal length in air of the microlens is shorter than f. : D makes it possible to “focus light on the openings of the black matrix pattern”.

In the case of Example 1, the thin film 121a formed by sintering of the sol-gel material has a thickness of 4 μm, the thin film 121b of SiO ₂ formed by sputtering has a thickness of 0.9 μm, the refractive index of the thin film 121a is n1, and the thin film 121b. If the refractive index of n2 is n2, the mechanical distance between the microlens surface and the black matrix is 4.9 μm, but the optical distance is “4 · n1 + 0.9 · n2”, and n1> 1, n2 Since> 1, the optical spacing is larger than the equivalent spacing in air. Therefore, by using a microlens with a long focal length, it is possible to reduce the thickness of the liquid crystal panel while suppressing light condensing by the microlens.

Incidentally, in Example 1, the refractive index of the quartz substrate 100 is 1.46, the radius of curvature of the microlens is 4 μm, the focal length in the air: f = 8 μm, the refractive index of the sintered layer 121a of the sol-gel material: n1 = The refractive index of the layer of 1.41 and SiO ₂ : n2 is 1.45.

The “opposite substrate for liquid crystal panel” of Example 2 has a configuration as shown in FIG. In order to avoid complications, the same reference numerals as those in FIG.
That is, in the counter substrate for the liquid crystal panel of Example 2, as shown in FIG. 3, four layers of thin films 1211, 1221, 1212, and 1222 are laminated on the surface of the microlens array substrate 10 on which the microlenses ML are formed. It is formed into a “liquid layer structure”.

Such a counter substrate for a liquid crystal panel was produced as follows.
The same quartz substrate 100 as used in Example 1 was prepared. The quartz substrate 100 has a parallel plate shape with a diameter of 100 mm and a thickness of 1 mm. A large number of microlens arrays MLA were arranged in a circle with a diameter of 80 mm of the quartz substrate 100. All the microlens arrays MLA have the same structure.

On the surface on which the microlens array MLA is formed, four layers of thin films 1211, 1221, 1212, and 1222 shown in FIG. 3 are stacked. As these thin films, the following were used. That is, “thin film obtained by firing a silica-based sol-gel material” was used as the thin films 1211, 1212, and “SIO ₂ thin film by sputtering” was used as the thin films 1221 and 1222, respectively.

As shown in Example 1, the amount of warping due to “a thin film obtained by firing a silica-based sol-gel material” and the amount of warping due to “a thin film of SIO ₂ by sputtering” are already known. Therefore, if the thicknesses of the thin film 1211 and the thin film 1221 are D11 and D21, respectively, the conditions for canceling the stress in the film surface direction with these thin films: 1211 and 1221 are as follows:
D21 = − (a / b) D11 = (1 / 4.5) D11
It is.

Similarly, if the thicknesses of the thin film 1212 and the thin film 1222 are D12 and D22, respectively, the conditions for canceling the stress in the film surface direction with these thin films: 1212 and 1222 are:
D22 = − (a / b) D12 = (1 / 4.5) D12
It is.
Therefore, if the film thicknesses D11, D12, D21, and D22 are set so as to satisfy the above-described conditions, the stress in the film surface direction is canceled as a whole for the four layers of the thin films 1211, 1221, 1212, and 1222, and the quartz is removed. Substantially “warping” can be prevented from occurring in the substrate 100.

As shown in FIG. 7B, a thin film 1211a obtained by firing a silica-based sol-gel material on a quartz substrate 100 is formed in a thickness: D11 = 33 μm by the same method as in the first embodiment. A sputtering film 1221a of SIO ₂ is formed thereon with a thickness: D21 = 0.75 μm, and a thin film 1212b obtained by firing a silica-based sol-gel material is formed with a thickness: D12 = 3.3 μm. No. ₂ sputtering film 1222b was formed to a thickness: D22 = 0.75 μm.

As a result, the quartz substrate 100 was not substantially warped.
After forming the SiO ₂ thin film 1222b, a Cr layer was 90nm deposited Cr by sputtering onto the SiO ₂ film 1222b, thereon, to form a black matrix pattern by photolithography, the resist layer by wet etching The black matrix pattern was transferred onto the Cr layer, and the resist residue was removed by washing with a “sulfuric acid / hydrogen peroxide mixture”.

After that, after forming ITO as a transparent conductive film to a thickness of 130 nm on the Cr layer patterned as a black matrix pattern, the arrayed microlens arrays were separated separately, and each one was “microlens array”. A liquid crystal panel counter substrate having a substrate, a laminate structure, a black matrix, and a transparent conductive film was obtained. This counter substrate for a liquid crystal panel had no substantial warpage.

Incidentally, the focal length of each microlens formed on the quartz substrate 100 used in the second embodiment: f = 12 μm is larger than that of the first embodiment (8 μm), and therefore, between the microlens surface and the black matrix pattern. In order to increase the optical distance, it is necessary to make the “stack thickness” of the four thin films larger than in the case of the first embodiment. For this reason, a thin film obtained by firing a silica-based sol-gel material on the quartz substrate 100. And four layers of SIO ₂ thin films formed by sputtering are alternately laminated so that “the whole of the four thin films cancels out stress in the direction of the film surface” so that stress that causes warpage of the quartz substrate 100 does not act. Yes.

Instead of doing this, on the quartz substrate 100, one thin film obtained by firing a silica-based sol-gel material and one SIO ₂ sputtering film may be laminated in a total of two layers to cancel the stress. Good. However, in this case, the thickness of each thin film is increased in order to increase the optical film thickness. As described above, since the stress in the film surface direction of the formed thin film is proportional to the film thickness, the stress in the film surface direction generated in the film increases as the film thickness of the formed thin film increases.

For this reason, if stress is canceled by two layers having a large thickness, large stress cancellation is performed between the films. In some cases, the silica-based sol-gel material is baked to form a thick thin film. There is a possibility that permanent distortion may occur in the substrate. If permanent distortion occurs, the distortion of the quartz substrate cannot be removed even with the elongation stress of the SIO ₂ thin film caused by sputtering, and the quartz substrate remains warped. There is also a risk of it.

From this point of view, when the thickness of the laminated film to be formed is large to some extent, the thin film that generates tensile stress and the thin film that generates tensile stress are alternately stacked in four or more layers, and the stress cancellation as a whole Good to do.

It is a figure for demonstrating the structure of a liquid crystal panel. It is a figure for demonstrating an example of the opposing board | substrate for liquid crystal panels. It is a figure for demonstrating another example of the opposing board | substrate for liquid crystal panels. It is a figure for demonstrating an Example. It is a figure for demonstrating the curvature of the board | substrate by tensile stress. It is a figure for demonstrating the curvature of the board | substrate by an extension stress. It is a figure for demonstrating two examples of a film | membrane laminated substrate.

Explanation of symbols

10 Microlens array substrate
ML micro lens
12 Film laminated structure
14 Black matrix pattern
16 liquid crystal
18 Electrode film 20 Substrate

Claims (6)

A film laminated substrate formed by laminating N layers (4 ≧ N ≧ 2) thin films on at least one surface of a flat substrate, and a silica base that shrinks in the film surface direction during film formation on at least one surface of the substrate M pairs (1 ≦ M ≦ N / 2) are formed of a thin film obtained by firing the sol-gel material of the above and a thin film of SiO ₂ by sputtering that extends in the film surface direction during film formation,
In each thin film pair of the thin film that contracts in the film surface direction during film formation and the thin film that extends in the film surface direction during film formation, the film thickness after firing of the thin film that contracts in the film surface direction during film formation: d1; The film thickness d2 of the thin film that extends in the film surface direction during film formation is d2
d2 = (1 / 4.5) d1
By satisfying
The film thickness of each of the M pairs of thin films is set so that the stress in the film surface direction is canceled out and the stress that causes warping of the substrate does not act as the entire N layer thin film formed on one side. A laminated film substrate characterized by the above. The film laminated substrate according to claim 1,
Number of thin film pairs: A film laminated substrate , wherein M is 1 and the thin film that does not constitute the thin film pair is a layer that does not generate stress during film formation. The film laminated substrate according to claim 1 or 2,
A film laminated substrate, wherein a micro-optical surface is formed on a surface of a flat substrate on a side where an N-layer thin film is formed. The film-formed substrate according to claim 3,
A film laminated substrate, wherein the micro optical surface formed on the surface of the flat substrate on the side on which the N-layer thin film is formed is a microlens array or an array of microlens arrays.   5. An array of microlens arrays is formed on one side of a flat substrate of the film laminated substrate according to claim 4, and the microarrays are arranged on an N-layer thin film stacked on the flat substrate. A counter substrate for a liquid crystal panel, in which a black matrix pattern for light shielding and a transparent conductive film corresponding to the arrangement of microlenses are formed for each lens array, and obtained separately for each microlens array.   6. A liquid crystal panel comprising a liquid crystal layer sealed between a counter substrate for a liquid crystal panel according to claim 5 and a drive electrode substrate.

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