JP2004226639A - Manufacturing method of microlens array - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely manufacture a microlens array having convex lenses which have high protrusion heights. <P>SOLUTION: A plurality of negative resist layers are formed on a first substrate through a plated substrate film. A metal layer 14, which has recessed sections corresponding to the plurality of negative resist layers and which is made of an Ni-Fe alloy or the like, is formed in a plating process. The plated substrate layer and the plurality of the negative resist layers are removed. The back surface of the layer 14 is fixed to a second substrate 16 by an adhesive layer 18. Positive resist layers having R<SB>11</SB>or the like are formed on the recessed sections of the layer 14 through a water-soluble polymer layer 20. The substrate 16 is turned over and each positive resist layer is adhered to one of the main surfaces of a quartz substrate 22. The layer 14 and the substrate 16 are separated from the substrate 22 by dissolving the layer 20. Positive resist layers are subjected to heated reflow processing to provide a convex lens shape. The shape of the positive resist layer is transferred to the substrate 22 by an etching process to form a convex lens. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a microlens array having a convex lens having a high protrusion height.
[0002]
[Prior art]
Conventionally, as a method of manufacturing a microlens array, a positive resist layer corresponding to a desired lens is formed on one main surface of a quartz substrate by photolithography, and then the positive resist layer is directed downward (in the same direction as gravity). The positive resist layer is subjected to a heat reflow treatment to give a convex lens shape to the positive resist layer, and the convex lens shape of the positive resist layer is transferred to one main surface of the quartz substrate by dry etching to form a convex lens. It is known (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-7-174903
[Problems to be solved by the invention]
According to the above-mentioned prior art, when the thickness of the positive resist layer is, for example, 1.5 μm, a convex lens having a protrusion height of about 2 μm is obtained. In order to increase the projection height of the convex lens, the thickness of the positive resist layer may be increased. However, with the performance of the current positive resist, the thickness that can be patterned (thickness at the resolution limit) is about 30 μm to 40 μm, and it is difficult to form a convex lens having a higher protruding height.
[0005]
On the other hand, a negative resist can form a thicker pattern than a positive resist. This is based on the difference in the pattern formation principle that the exposed part is dissolved by development and the unexposed part remains in the positive resist, whereas the unexposed part is dissolved by the development and the exposed part remains in the negative resist. . At present, a negative resist pattern having a thickness of about 500 μm is formed. However, since the exposed portion of the negative resist becomes resin, a convex lens shape cannot be imparted by the heat reflow treatment.
[0006]
An object of the present invention is to provide a novel microlens array manufacturing method capable of accurately manufacturing a microlens array having a convex lens having a high protrusion height.
[0007]
[Means for Solving the Problems]
The method for manufacturing the first microlens array according to the present invention includes:
Forming a negative resist layer corresponding to a desired convex lens on one main surface of the first substrate via a plating underlayer by photolithography;
A step of forming a metal layer by plating on the plating base layer so as to cover the negative resist layer, and providing a concave portion corresponding to the negative resist layer in the metal layer;
Removing the plating underlayer and separating the metal layer from the first substrate;
Removing the negative resist layer from the separated metal layer to expose the recess,
Fixing the metal layer to the second substrate such that the surface of the metal layer opposite to the concave side faces one main surface of the second substrate;
Forming a resin layer made of a filled resin having a shape corresponding to the concave portion of the metal layer by filling the concave portion of the metal layer with a reflowable resin through a soluble sacrificial film,
A step of separating the metal layer and the second substrate from the resin layer by dissolving the sacrificial film in a state where the resin layer is in close contact with one main surface of a third substrate made of a lens material;
Performing a heat reflow treatment on the resin layer on one main surface of the third substrate to impart a convex lens shape to the resin layer;
Transferring the convex lens shape of the resin layer to one main surface of the third substrate by etching to form a convex lens.
[0008]
According to the first microlens array manufacturing method, a metal layer is formed by plating using a negative resist layer corresponding to a desired convex lens as a mask, and a concave portion corresponding to the negative resist layer is provided in the metal layer. . The concave portions are exposed by removing the negative resist layer from the metal layer. By filling a concave portion of the metal layer with a reflowable resin (for example, a positive resist layer) via a soluble sacrificial film, a resin layer made of a filling resin having a shape corresponding to the concave portion is formed. The metal layer is separated from the resin layer by dissolving the sacrificial film in a state of being in close contact with the lens material substrate. By performing a heating reflow process on the resin layer in the lens material substrate, a convex lens shape is imparted to the resin layer, and the convex lens shape is formed by transferring the convex lens shape to the substrate surface by etching. The negative resist layer can be formed with a thickness of 50 μm or more, and a convex lens having a protrusion height of 50 μm or more can be manufactured with high accuracy.
[0009]
The method for manufacturing the second microlens array according to the present invention includes:
Forming a negative resist layer corresponding to a desired convex lens by photolithography on one main surface of the first substrate via a first plating base layer;
Forming a metal layer by plating on the first plating base layer so as to cover the negative resist layer, and providing a concave portion corresponding to the negative resist layer in the metal layer;
Removing the first plating underlayer and separating the metal layer from the first substrate;
Removing the negative resist layer from the separated metal layer to expose the recess,
Fixing the metal layer to the second substrate such that the surface of the metal layer opposite to the concave side faces one main surface of the second substrate;
Forming a resin layer made of a filled resin having a shape corresponding to the concave portion of the metal layer by filling the concave portion of the metal layer with a reflowable resin through a soluble sacrificial film,
Separating the metal layer and the second substrate from the resin layer by dissolving the sacrificial film in a state where the resin layer is adhered to one main surface of the third substrate;
Performing a heat reflow treatment on the resin layer on one main surface of the third substrate to impart a convex lens shape to the resin layer;
Forming a second plating base layer on one main surface of the third substrate so as to cover the resin layer provided with the convex lens shape;
Forming a plating metal mold having a spherical concave portion corresponding to the convex lens shape of the resin layer by plating a metal on the second plating base layer;
Removing the second plating base layer and separating the mold from the third substrate;
Forming a convex lens corresponding to a concave portion of the molding die on one main surface of the lens material layer using the separated molding die.
[0010]
The manufacturing method of the second microlens array is the same as the manufacturing method of the first microlens array except that another substrate is used instead of the lens material substrate up to the step of performing the heat reflow treatment on the resin layer. After the heating reflow process, a plating process using a resin layer provided with a convex lens shape forms a plating metal mold having a spherical recess corresponding to the convex lens shape, and the spherical recess is formed using the mold. Is formed. According to such a manufacturing method, by setting the thickness of the negative resist layer to 50 μm or more, it is possible to mass-produce convex lenses having a protrusion height of 50 μm or more with high accuracy.
[0011]
In the method of manufacturing the first or second microlens array, in the step of forming the negative resist layer, the negative resist layer is formed so as to gradually decrease in size from a lower portion to an upper portion, and a concave portion is formed in the metal layer. In the step of providing the concave portion, the concave portion may be provided so that the size gradually increases as the concave portion advances from the bottom to the opening end. This facilitates the separation operation in the step of separating the metal layer and the second substrate from the resin layer.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
1 to 10 show a method for manufacturing a microlens array according to one embodiment of the present invention.
[0013]
In the process of FIG. 1, a Cr layer and a Cu layer are sequentially formed on one main surface of a first substrate 10 made of quartz, silicon, glass, or the like by a sputtering method to form a Cu / Cr stack (a Cu layer is stacked on a Cr layer). (Laminated) 12 is formed. The Cu / Cr laminate 12 is used as a plating underlayer, and the thicknesses of the Cr layer and the Cu layer can be set to 20 nm and 150 nm, respectively. The Cr layer is used to improve the adhesion of the Cu layer.
[0014]
In the step of FIG. 2, negative resist layers R _{1 to} R ₆ corresponding to the desired six convex lenses are formed on the Cu / Cr laminate 12 by photolithography. Each negative resist layer, such as R ₁ may be a diameter 0.5 mm, thickness t is formed so as to 70 [mu] m.
[0015]
In the step of FIG. 3, a metal layer 14 made of a Ni—Fe alloy is formed on the Cu / Cr stack 12 by, for example, plating with a Ni—Fe alloy so as to cover the resist layers R _{1 to} R ₆ . The thickness T of the metal layer 14 can be set to 200 μm. The metal layers 14 are provided with concave portions Q _{1 to} Q ₆ corresponding to the resist layers R _{1 to} R ₆ , respectively.
[0016]
In the step of FIG. 4, at least the Cu layer in the Cu / Cr laminate 12 is removed by etching to separate the metal layer 14 from the substrate 10. Then, the resist layers R _{1 to} R ₆ attached to the metal layer 14 are removed by a chemical solution treatment or the like to expose the concave portions Q _{1 to} Q ₆ respectively corresponding to the resist layers R _{1 to} R ₆ . Thereafter, the metal layer 14 is bonded to the adhesive layer 18 such that the surface of the metal layer 14 opposite to the surface on the side of the concave portions Q _{1 to} Q ₆ faces one main surface of the second substrate 16 made of quartz or the like. To fix and adhere to the substrate 16.
[0017]
In the process shown in FIG. 5, applying a water-soluble polymer film 20 as a sacrificial layer of solubility on the surface of the recess Q ₁ to Q ₆ side of the metal layer 14. Polymer film 20 is formed so as to cover the bottom and side wall surfaces in each recess such Q _1.
[0018]
In the step of FIG. 6, the positive resist having a shape corresponding respectively to the positive resist recess Q ₁ to Q ₆ is filled in the recess Q ₁ to Q ₆ of the metal layer 14 via the polymer film 20 as a reflow of the resin forming a layer _R 11 _{to R 16.} Each resist layer such as R ₁₁ is formed so as to form a flat surface with the plane of the surrounding.
[0019]
In the step of FIG. 7, it is brought into close contact with the resist layer R ₁₁ to R ₁₆ on the one main surface of the quartz substrate 22 as the lens material substrate is turned over the structure shown in FIG.
[0020]
In the process shown in FIG. 8, separating the metal layer 14 and the substrate 16 from the resist layer R ₁₁ to R ₁₆ by dissolving the polymer film 20 was immersed in water at close contact state as shown in FIG. Each resist layer such as R ₁₁ is left in a state of being in close contact with the one main surface of the quartz substrate 22.
[0021]
In the step of FIG. 9, the resist layers R _{11 to} R ₁₆ are subjected to a heat reflow treatment on one main surface of the substrate 22 so that each resist layer such as R ₁₁ has a convex lens shape. Each resist layer such as R _11, the height from before the reflow is increased after the reflow, is the height of about 100μm when the resist thickness t was 70μm in the step of FIG.
[0022]
In the process shown in FIG. 10, a convex lens _L 1 ~L ₆ respectively corresponding to the convex lens shape of the resist layer _R 11 _{to R 16} by a dry etching process to the resist layer _R 11 _{to R 16} is transferred to one main surface of the substrate 22 It is formed on one main surface of the substrate 22. In the dry etching treatment, etching can be performed using a fluorine-based gas such as CHF ₃ , CF ₄ , C ₃ F ₈ or a mixed gas thereof, or a gas in which oxygen, argon, or the like is added thereto.
[0023]
According to production method described above, the projection height H of each lens, such as L ₁ is obtained a microlens array, which is also 100 [mu] m, the accuracy of the pitch P between adjacent lenses, such as L _1, L ₂ is, ± 0 High precision of 0.5 μm or less was obtained.
[0024]
FIG. 11 shows a metal layer 14 'according to a modification. This metal layer 14' can be used in place of the metal layer 14 described above in the steps of FIGS.
[0025]
To obtain a metal layer 14 'of FIG. 11 may be formed so that the size gradually decreases as it travels both the negative resist layer R ₁ to R ₆ from bottom to top in the step of FIG. In order to obtain such a forward tapered resist shape, when a stepper (reduction projection exposure apparatus) is used,
(1) a method of setting the focus position in the resist,
(2) In the exposure mask, any one of the methods of gradually changing the transmittance of the mask portion (to increase the transmittance toward the bottom of the resist) can be used.
[0026]
If each resist layer such as R ₁ in step 2 was tapered forward, in the plating step 3, the process proceeds to the open end of the recess Q ₁₁ to Q ₁₆ are both bottom as shown in FIG. 11 Is applied to the metal layer 14 ′ so that the size gradually increases. The use of such metal layer 14 ', in the step of FIG. 6, the positive resist layer _R 11 _{to R 16} is formed in a shape corresponding respectively to the recess _Q 11 _{to Q 16,} in the step of FIG. 8, the resist layer R When separating the metal layer 14 ′ from _{11 to} R ₁₆ , the separating operation is facilitated.
[0027]
12 to 15 show a method of manufacturing a microlens array according to another embodiment of the present invention. In this manufacturing method, the steps up to and including the step in FIG. 12 are the same as the steps described above with reference to FIGS. 1 to 9, and the same portions are denoted by the same reference numerals and detailed description thereof will be omitted. However, the substrate 22 is not limited to the lens material substrate, and may be an opaque substrate such as a metal.
[0028]
In the step of FIG. 12, a Cu / Cr laminate 24 as a plating underlayer is formed on one main surface of the substrate 22 by a sputtering method so as to cover the positive resist layers R _{11 to} R _{16 provided} with the convex lens shape by the heat reflow process. I do. The thicknesses of the Cr layer and the Cu layer can be 20 nm and 150 nm, respectively.
[0029]
In the step of FIG. 13, a mold 26 made of a Ni—Fe alloy is formed on the Cu / Cr laminate 24 by, for example, plating of a Ni—Fe alloy. The plating thickness at this time can be about 200 μm. The mold 26, the resist layer _R 11 recess _Q 21 _{to Q 26,} respectively in a convex lens shape corresponding spherical in _{to R 16} is applied.
[0030]
In the step of FIG. 14, to separate the mold 26 is removed by etching at least a Cu layer of the Cu / Cr laminate 24 from the substrate 22 and the resist layer _R 11 _{to R 16.} As a result, the recess _Q 21 _{to Q 26} of the mold 26 is exposed.
[0031]
Figure in 15 steps, each mold 26 in the recess Q ₂₁ to Q ₂₆ on one main surface of the glass layer 28 as the lens material layer by securing the type of seat for glass mode performs glass molding process to form the corresponding convex lens _L 11 _{~L 16.} Then, separating the glass layer (microlens array) 28 having a convex lens _L 11 _{~L 16} from the mold 26. Thereafter, by repeating the same glass molding process, the micro lens array can be mass-produced.
[0032]
According to production method described above with respect to FIG. 12 to _15, the projecting height of the convex lenses, such as _{L 11} is obtained a microlens array, which is also 100 [mu] _m, the pitch accuracy between adjacent lenses, such as L _{11, L 12} is High accuracy of ± 0.5 μm or less was obtained.
[0033]
In the embodiment described above, the lens arrangement is a one-dimensional arrangement, but may be a two-dimensional arrangement. Further, a concave lens type microlens array may be manufactured using the convex lens type microlens array obtained in the process of FIG. 10 or FIG. That is, after transferring the convex lens pattern of the convex lens type microlens array as a concave lens pattern to a fluid resin layer formed on a lens material substrate, this resin layer is cured, and the concave lens pattern of the resin layer is etched by a lens material. The concave lens type microlens array may be manufactured by transferring to a substrate.
[0034]
【The invention's effect】
As described above, according to the present invention, a negative resist pattern is transferred as a concave pattern to a plated metal layer by plating, and a reflowable resin layer is formed in a concave of the plated metal layer via a soluble sacrificial film. Dissolves the sacrificial film while the resin layer is in close contact with one main surface of the lens material substrate, separates the plated metal layer from the resin layer, and gives the resin layer a convex lens shape by heating and reflow processing on the lens material substrate Then, the convex lens shape of the resin layer is transferred to one main surface of the lens material substrate by etching to form the convex lens, so that the effect of accurately manufacturing a microlens array having a convex lens having a high protrusion height is obtained. can get.
[0035]
In addition, another substrate is used in place of the lens material substrate, a convex lens shape is imparted to the resin layer by heating reflow processing on the other substrate, and then the convex lens shape of the resin layer is transferred to a molding die by plating treatment. Is used to form a convex lens, so that an effect of accurately mass-producing a microlens array having a convex lens having a high protrusion height can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a Cu / Cr layer forming step in a method for manufacturing a microlens array according to an embodiment of the present invention.
FIG. 2 is a sectional view showing a negative resist layer forming step following the step of FIG. 1;
FIG. 3 is a cross-sectional view showing a plating step following the step of FIG. 2;
FIG. 4 is a cross-sectional view showing a metal layer separating step, a resist removing step, and a metal layer bonding step following the step of FIG. 3;
FIG. 5 is a cross-sectional view showing a water-soluble polymer application step following the step of FIG. 4;
FIG. 6 is a cross-sectional view showing a positive resist layer forming step following the step of FIG. 5;
FIG. 7 is a cross-sectional view showing a positive resist layer adhesion step following the step of FIG. 6;
8 is a cross-sectional view showing a water-soluble polymer dissolving step and a metal layer separating step following the step of FIG.
FIG. 9 is a cross-sectional view showing a heating reflow step following the step of FIG. 8;
FIG. 10 is a cross-sectional view showing a lens forming step following the step in FIG. 9;
FIG. 11 is a cross-sectional view showing a modification of the metal layer.
FIG. 12 is a cross-sectional view showing a Cu / Cr layer forming step in a method for manufacturing a microlens array according to another embodiment of the present invention.
FIG. 13 is a cross-sectional view showing a plating step following the step of FIG.
FIG. 14 is a cross-sectional view showing a mold separating step following the step of FIG.
15 is a cross-sectional view showing a glass forming step following the step in FIG.
[Explanation of symbols]
10: first substrate, 12, 24: Cu / Cr laminate, 14, 14 ': metal layer, 16: second substrate, 18: adhesive layer, 20: water-soluble polymer film, 22: quartz substrate, 26: mold, 28: glass _layer, R 1 to R _6: a negative resist _layer, R 11 _{to R 16:} the positive resist _{layer, Q 1 ~Q 6, Q 11} ~Q 16, Q 21 ~Q 26: recess, _{L 1 ~L 6, L} 11 ~L _16: convex lens.

Claims (3)

Forming a negative resist layer corresponding to a desired convex lens on one main surface of the first substrate via a plating underlayer by photolithography;
A step of forming a metal layer by plating on the plating base layer so as to cover the negative resist layer, and providing a concave portion corresponding to the negative resist layer in the metal layer;
Removing the plating underlayer and separating the metal layer from the first substrate;
Removing the negative resist layer from the separated metal layer to expose the recess,
Fixing the metal layer to the second substrate such that the surface of the metal layer opposite to the concave side faces one main surface of the second substrate;
Forming a resin layer made of a filled resin having a shape corresponding to the concave portion of the metal layer by filling the concave portion of the metal layer with a reflowable resin through a soluble sacrificial film,
A step of separating the metal layer and the second substrate from the resin layer by dissolving the sacrificial film in a state where the resin layer is in close contact with one main surface of a third substrate made of a lens material;
Performing a heat reflow treatment on the resin layer on one main surface of the third substrate to impart a convex lens shape to the resin layer;
Transferring a convex lens shape of the resin layer to one main surface of the third substrate by etching to form a convex lens. Forming a negative resist layer corresponding to a desired convex lens by photolithography on one main surface of the first substrate via a first plating base layer;
Forming a metal layer by plating on the first plating base layer so as to cover the negative resist layer, and providing a concave portion corresponding to the negative resist layer in the metal layer;
Removing the first plating underlayer and separating the metal layer from the first substrate;
Removing the negative resist layer from the separated metal layer to expose the recess,
Fixing the metal layer to the second substrate such that the surface of the metal layer opposite to the concave side faces one main surface of the second substrate;
Forming a resin layer made of a filled resin having a shape corresponding to the concave portion of the metal layer by filling the concave portion of the metal layer with a reflowable resin through a soluble sacrificial film,
Separating the metal layer and the second substrate from the resin layer by dissolving the sacrificial film in a state where the resin layer is adhered to one main surface of the third substrate;
Performing a heat reflow treatment on the resin layer on one main surface of the third substrate to impart a convex lens shape to the resin layer;
Forming a second plating base layer on one main surface of the third substrate so as to cover the resin layer provided with the convex lens shape;
Forming a plating metal mold having a spherical concave portion corresponding to the convex lens shape of the resin layer by plating a metal on the second plating base layer;
Removing the second plating base layer and separating the mold from the third substrate;
Forming a convex lens corresponding to a concave portion of the molding die on one main surface of the lens material layer using the separated molding die. In the step of forming the negative resist layer, the negative resist layer is formed so as to gradually decrease in size as proceeding from the lower part to the upper part, and in the step of providing the metal layer with a concave part, the concave part is formed from the bottom to the open end. 3. The method for manufacturing a microlens array according to claim 1, wherein the size is gradually increased as the process proceeds.

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