JP4241060B2 - Method for forming inclined surface of microlens array - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of forming an inclined surface for suppressing reflected return light on a light incident surface opposite to a lens forming surface in a microlens array.
[0002]
[Prior art]
Conventionally, in a microlens array for collimating (collimating) light emitted from an optical fiber, a light incident surface opposite to the lens forming surface is provided with an inclined surface having an inclination angle of about 8 degrees from the light incident surface. It is known that reflected return light is prevented from entering the optical fiber.
[0003]
As a method of forming an inclined surface in a microlens array, after forming a bar-shaped microlens array by dicing a lens substrate in which a large number of lenses are formed in a matrix on one main surface for each row, for example, A method is used in which a bar-shaped microlens array is mounted on a polishing jig so that the other main surface has a predetermined polishing angle (inclination angle) and is subjected to a polishing process. Although patents and utility model publications were searched using “microlens, antireflection, oblique” as a keyword, a technology close to the present invention could not be searched.
[0004]
[Problems to be solved by the invention]
According to the prior art described above, it is necessary to convert the microlens array in the wafer state (two-dimensional microlens array) into a bar-shaped microlens array (one-dimensional microlens array). Therefore, it is impossible to form an inclined surface for suppressing reflected return light. For this reason, work efficiency is inevitable due to handling in a bar state, attachment to and removal from a polishing jig, and the like. In addition, an antireflection film for preventing reflection at the interface may be formed on both surfaces of the microlens array after the inclined surface is formed. Such an antireflection film forming process is performed for each bar-shaped microlens array. The working efficiency was not good.
[0005]
An object of the present invention is to provide a novel method of forming an inclined surface of a microlens array that can efficiently form an inclined surface for suppressing reflected return light on the light incident surface of the microlens array in a wafer state.
[0006]
[Means for Solving the Problems]
The method of forming the inclined surface of the microlens array according to the present invention is as follows.
A step of creating a plurality of metal bar juxtaposed plates with a plurality of inclined surfaces in a sawtooth shape along one side in the length direction by a thin film process,
A step of holding the plurality of bar juxtaposed plates side by side so that the inclined surface positions are aligned in a direction perpendicular to the length direction of the bar juxtaposed plate with each inclined surface facing upward;
The step of arranging a plurality of prismatic bars on top of the plurality of bar juxtaposed plates by arranging a prismatic bar for each set of inclined surfaces aligned in a state where the plurality of bar juxtaposing plates are held side by side. When,
In a state where the plurality of prismatic bars are juxtaposed above the plurality of bar juxtaposed plates, the plurality of prismatic bars are bonded and fixed to a fixed substrate on the side opposite to the plurality of bar juxtaposed plates. Process,
In a state where the plurality of prismatic bars are fixed to the fixed substrate, the plurality of prismatic bars are saw-toothed on the side opposite to the fixed side by separating from the upper portions of the plurality of bar juxtaposed plates. A step of exposing the inclined surface chain pattern linked in a shape;
In a lens substrate having a plurality of lenses formed on one main surface, the inclined surface chain pattern of the plurality of prismatic bars is formed on the replica material layer formed on the other main surface, and the plurality of inclined surfaces are the plurality of lenses. And a process of transferring so as to face each other,
The inclined surface chain pattern transferred to the replica material layer is transferred to the other main surface of the lens substrate by an etching process so that the plurality of inclined surfaces are opposed to the plurality of lenses, respectively. Forming on the surface.
[0007]
According to the inclined surface forming method of the microlens array of the present invention, after a plurality of bar juxtaposed plates are formed by a thin film process, the plurality of bar juxtaposed plates are arranged such that the inclined surface positions are aligned with each inclined surface facing upward. Hold them side by side. At this time, it is convenient to use a juxtaposed plate holder having juxtaposed plate insertion grooves juxtaposed on one main surface as the holding means.
[0008]
In a state where a plurality of bar juxtaposed plates are held side by side, a prismatic bar is arranged for each set of inclined surfaces whose positions are aligned, and a plurality of prismatic bars are juxtaposed on top of the plurality of bar juxtaposed plates. The plurality of prismatic bars can be easily created by dicing a plate material made of quartz or the like. In a state where a plurality of prismatic bars are juxtaposed on top of a plurality of bar juxtaposed plates, a plurality of prismatic bars are bonded and fixed to a fixed substrate on the side opposite to the bar juxtaposed plate side. Are separated from the upper part of a plurality of bar juxtaposed plates. As a result, the plurality of prismatic bars fixed to the fixed substrate are exposed to an inclined surface chain pattern in which a plurality of inclined surfaces are connected in a sawtooth shape on the side opposite to the fixed side.
[0009]
Thereafter, the inclined surface chain pattern of the plurality of prismatic bars is transferred to the replica material layer made of resin or the like formed on the other main surface in the lens substrate on which the plurality of lenses are formed on one main surface. Then, the inclined surface chain pattern transferred to the replica material layer is transferred to the other main surface of the lens substrate by etching to form a plurality of inclined surfaces so as to face the plurality of lenses, respectively.
[0010]
As described above, in this invention, the inclined surface chain pattern is transferred to the replica material layer on the lens substrate, and the inclined surface chain pattern of the replica material layer is transferred to the lens substrate by the etching process. Thus, the inclined surface can be efficiently formed in the wafer state.
[0011]
In the method of forming the inclined surface of the microlens array according to the present invention, lenses arranged in a matrix as the plurality of lenses are formed on one main surface of the lens substrate, and the plurality of prismatic bars are formed on the replica material layer. In the step of transferring the inclined surface chain pattern, transfer is performed so that a plurality of inclined surfaces respectively face a plurality of lens rows (or lens columns) of the lens substrate, and the inclined surface chain pattern of the replica material layer is transferred to the In the step of transferring to the other main surface of the lens substrate, a plurality of inclined surfaces may be formed so as to face the plurality of lens rows (or lens columns) of the lens substrate. In this way, it is possible to efficiently form the inclined surface in the wafer state without dividing the lens substrate on which the lenses having the matrix arrangement (two-dimensional arrangement) are formed.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
1 to 6 show a method of forming an inclined surface of a microlens array according to an embodiment of the present invention, and steps (1) to (6) corresponding to the respective drawings will be sequentially described.
[0013]
(1) The bar juxtaposed plate 12a made of a Ni—Fe alloy is formed by a thin film process including plating. A specific method for producing the bar juxtaposed plate will be described later with reference to FIGS. The bar juxtaposed plate 12a is, for example, an elongated rectangular shape, and is provided such that the inclined surfaces R _{1 to} R ₇ are connected in a sawtooth shape along one side in the length direction. In the bar juxtaposed plate 12a, the length A can be 60 mm, the thickness T (see FIGS. 7 and 15) can be 50 to 100 μm, and the inclination angle θ of the inclined surface can be 5 to 15 degrees (preferably 8 degrees). The bar juxtaposed plate 12a having the inclination angle θ is formed with an accuracy of 0.1 to 0.2 μm, which is equal to the accuracy of the reduction projection exposure apparatus, because the resist pattern is determined using the reduction projection exposure apparatus in the thin film process. it can.
[0014]
In the process of FIG. 1, bar juxtaposed plates 12b and 12c (see FIG. 7) having the same configuration as the bar juxtaposed plate 12a are formed by a thin film process. In this embodiment, three bar juxtaposed plates 12a to 12c are used, but the number of bar juxtaposed plates used may be two or three or more.
[0015]
(2) Next, in the juxtaposed plate holder 10 as shown in FIG. 7, the juxtaposed plate insertion grooves 10a, 10b, 10c juxtaposed on one main surface are arranged with the juxtaposed plates 12a, 12b, 12c on the inclined surfaces. Insert each so that it faces upward. At this time, the bar juxtaposed plates 12a to 12c are in a state of being held side by side so that the inclined surface positions are aligned in a direction orthogonal to the length direction of the bar juxtaposed plate. Insertion groove 10a, spacing and insertion grooves 10b between 10b, the spacing between 10c, juxtaposed plate 12a~12c is previously set corresponding to the length of the quartz bar can hold the quartz bar _B 1 .about.B ₇ Yes.
[0016]
The quartz bars B _{1 to} B ₇ are formed by, for example, dicing a quartz plate, and are all in the shape of a prism (a cross section perpendicular to the length direction is a quadrilateral shape). In each quartz bar ₁ such B, the length Q respectively 1.2mm and 1.5mm of length P and Rinhen cross section of one side perpendicular to the longitudinal direction, the length R may be a 76mm .
[0017]
As shown in FIG. 7, a quartz bar is disposed on the upper side of the bar juxtaposed plates 12a to 12c held in parallel on the juxtaposed plate holder 10 for each pair of inclined surfaces having the same position. B _{1 to} B ₇ are juxtaposed. The cross-section shown in FIG. 2 corresponds to a cross section taken along a line so as to pass through the and inclined surfaces R ₁ to R ₇ along the length of the bar juxtaposition plate 12a shown in FIG. In the upper part of juxtaposed plates 12a, quartz bars _B 1 .about.B ₇ is held respectively by the inclined surfaces _R 1 to R _7, juxtaposed plates 12b, quartz bars _B 1 .about.B ₇ in the same manner in 12c is held The Since the apposition plate 12a~12c is dimensioned precisely formed by a thin film process, it can be accurately juxtaposed quartz bar _B 1 ~B _7.
[0018]
(3) In a state where the quartz bar _B 1 .about.B ₇ at the top of the bar juxtaposed plates 12a~12c is juxtaposed, the fixed substrate by an adhesive layer 16 on the opposite side to the quartz bar _B 1 .about.B ₇ apposition plate side 14 Adhere and fix to. As the fixed substrate 14, a quartz substrate having a thickness of about 2 mm can be used. As the adhesive constituting the adhesive layer 16, an ultraviolet curable UV adhesive can be used. In this case, a UV adhesive is applied to one main surface of the substrate 14 and the one main surface of the substrate 14 is pushed onto the quartz bars B _{1 to} B ₇ via the adhesive layer 16 in a state where it is fluid or flexible. In this state, fixing is achieved by irradiating the adhesive layer 16 with ultraviolet rays to cure the adhesive layer 16.
[0019]
(4) separating the quartz bar _B 1 .about.B ₇ which is fixed to the substrate 14 from the upper left bar juxtaposition plate 12a~12c fixed state. As a result, the quartz bars B _{1 to} B ₇ are exposed to an inclined surface chain pattern in which a plurality of inclined surfaces R _{11 to} R ₁₇ are connected in a sawtooth shape on the side opposite to the fixed side.
[0020]
Next, a lens substrate 18 made of quartz or the like is prepared. On one main surface of the lens substrate 18, as shown in FIGS. 4 and 8, lenses L ₁₁ , L ₁₂ , L ₁₃ , L ₁₄ ... Are convex in a matrix along the X and Y directions orthogonal to each other. _{L 21, L 22, L 23} , L 24 ..., L 31, L 32, L 33, L 34 ..., L 41, L 42, L 43, L 44 ..., L 51 ..., L 61 ..., L 71 ... Is formed. A replica material layer 20 is formed on the other main surface of the lens substrate 18 by a coating method or the like. As the replica material layer 20, a resin such as an epoxy resin, a silicone resin, or a resist can be used. The replica material layer 20 is used as an etching mask in a later process and can be formed with a thickness of about 0.1 to 0.2 mm.
[0021]
(5) As shown in FIG. 4, the side opposite to the fixed side of the quartz bars B _{1 to} B ₇ fixed to the fixed substrate 14 is pressed against the replica material layer 20 on the lens substrate 18 to obtain FIG. As shown, the inclined surface chain patterns of the quartz bars B _{1 to} B ₇ are transferred to the replica material layer 20. In order to facilitate separation of the quartz bars B _{1 to} B ₇ from the replica material layer 20 after the transfer, a release agent may be applied to the opposite side of the quartz bars B _{1 to} B _{7 from} the fixed side before the transfer. In FIG. 5, R _{21 to} R ₂₇ indicate inclined surfaces formed corresponding to the inclined surfaces R _{11 to} R ₁₇ of the quartz bars B _{1 to} B ₇ , respectively, and the replica material layer 20 includes the inclined surfaces R ₂₁ to R ₂₁ . a state having an inclined surface chained pattern R ₂₇ is connected to a sawtooth.
[0022]
When transferring the inclined surface chain pattern of the quartz bars B _{1 to} B ₇ to the replica material layer 20, as shown in FIGS. 5 and 8, the inclined surfaces R ₂₁ , R ₂₂ ... R ₂₇ are lenses L ₁₁ , L ₂₁ . Transfer is performed so as to face the first to seventh lens rows including L ₇₁ , respectively. As another example, transfer is performed so that the inclined surfaces R ₂₁ , R ₂₂ ... R ₂₇ face the first to seventh lens rows including lenses L ₁₁ , L ₁₂ ... L ₁₇ (not shown), respectively. You may do it.
[0023]
(6) The replica material layer 20 is obtained by subjecting the other main surface of the lens substrate 18 to dry etching using the replica material layer 20 having the inclined surface chain pattern in which the inclined surfaces R _{21 to} R ₂₇ are arranged in a sawtooth shape as an etching mask. The inclined surface chain pattern is transferred to the other main surface of the lens substrate 18. As a result, the other main surface of the lens substrate 18 faces the first to seventh lens rows including the lenses L ₁₁ , L ₂₁ ... L ₇₁ as shown in FIGS. Inclined surfaces R ₃₁ , R ₃₂ ... R ₃₇ are formed.
[0024]
Inclined surface _R 21 in step 5 as described _{above, R} 22 ... a quartz bar _{B 1} to _{R 27} are each opposed to the first to seventh lens array that includes a lens _{L 11, L} 12 ... _{L 17} each If you make a transfer of the inclined surface the chain pattern of .about.B ₇ is inclined faces so that each faces the lens _{L 11,} L 12 _... L ₁₇ in the first to seventh lens array that includes each in the step of FIG. 6 R ₃₁ , R ₃₂ ... R ₃₇ are formed.
[0025]
9 and 10 show how the microlens array obtained by the above-described inclined surface forming method is used. The light beams L emitted from the optical fibers F _{11 to} F ₁₄ are respectively applied to the lenses L _{11 to} L ₁₄ formed on one main surface of the lens substrate 18 through the inclined surface R ₃₁ formed on the other main surface. incident, the incident light L is collimated for each lens, such as L _11. At this time, the inclined surface R ₃₁ having the inclination angle θ as shown in FIG. 10, a portion of the incident light L is reflected, the reflected light Lr is deviated from the optical fiber F _11, it does not enter the optical fiber F _11. That is, it is possible to reduce the reflected light incident on the reflected light and the optical fiber F ₁₂ back to the optical fiber F ₁₁ by providing the inclined surface R _31. This also applies to the other inclined surface such as R _32.
[0026]
FIGS. 11-16 shows an example of the bar juxtaposition board preparation method based on this invention.
[0027]
In the process of FIG. 11, a Cr layer 32 and a Cu layer 34 are sequentially deposited on one main surface of the quartz substrate 30 by sputtering to form a Cu / Cr laminate as a plating underlayer. The thicknesses of the Cr layer 32 and the Cu layer 34 can be about 15 nm and 200 nm, respectively. The Cr layer 32 is used for improving the adhesion of the Cu layer 34.
[0028]
In the step of FIG. 12, a resist layer 36 is formed on the Cu layer 34 by photolithography. As shown in FIG. 13, the resist layer 36 has an elongated rectangular plating hole 36A, and is formed so that inclined surfaces R _{41 to} R ₄₇ are connected in a sawtooth shape along one side in the length direction of the plating hole 36A. . Such a resist layer 36 can be formed with high dimensional accuracy using a reduction projection exposure apparatus in a photolithography process.
[0029]
In the process of FIG. 14, the bar juxtaposed plate 12 made of Ni—Fe alloy is formed by selective plating of Ni—Fe alloy using the resist layer 36 as a mask. The juxtaposed plate 12 can have a thickness T (see FIG. 15) of about 50 to 100 μm.
[0030]
In the process of FIG. 15, the resist layer 36 is removed by chemical treatment or the like, and the juxtaposed plate 12 is left. In the process of FIG. 16, at least the Cu layer 34 of the Cu / Cr stack is removed by an etching process to separate the juxtaposed plate 12 from the substrate 30. 16, the cross section of the juxtaposed plate 12 corresponds to a cross section of the juxtaposed plate 12 shown in FIG. 15 cut in the horizontal direction. The juxtaposed plate 12 has inclined surfaces R _{1 to} R ₇ formed corresponding to the inclined surfaces R _{41 to} R ₄₇ of the resist layer 36 shown in FIG. It is connected in a sawtooth shape along one side in the length direction. The substrate 30 on which the Cr layer 32 remains can be reused by returning to the step of FIG. 11 and forming the Cu layer 34 on the Cr layer 32 by sputtering.
[0031]
According to the above-described juxtaposed plate production method, the bar juxtaposed plate 12 having the inclined surfaces R _{1 to} R ₇ can be produced with high accuracy.
[0032]
【The invention's effect】
As described above, according to the present invention, the inclined surface for suppressing the reflected return light can be formed on the light incident surface of the microlens array in the wafer state. Therefore, even in the two-dimensional microlens array, the one-dimensional microlens An effect of efficiently forming the inclined surface without dividing the array is obtained.
[0033]
In addition, an etching mask in which a plurality of inclined surfaces are connected in a sawtooth shape using a metal bar juxtaposed plate made by a thin film process is transferred to the lens substrate by etching. There is also an effect that it is possible to form an inclined surface with high accuracy.
[0034]
In addition, when the anti-reflection film forming process is performed on both surfaces of the microlens array after the inclined surface is formed, the process can be performed in the wafer state, which has an advantage of improving the working efficiency.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a bar juxtaposed plate used in an inclined surface forming method of a microlens array according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a process of juxtaposing quartz bars using the bar juxtaposition plate of FIG.
3 is a cross-sectional view showing a quartz bar fixing step subsequent to the step of FIG. 2. FIG.
4 is a cross-sectional view showing a replica material layer forming step that follows the step of FIG. 3. FIG.
FIG. 5 is a cross-sectional view showing an inclined surface chain pattern transfer process subsequent to the process of FIG. 4;
FIG. 6 is a cross-sectional view showing an etching process for transferring an inclined surface chain pattern of a replica material layer to a lens substrate.
7 is a perspective view showing in detail a quartz bar juxtaposition process of FIG. 2; FIG.
FIG. 8 is a plan view showing a lens arrangement and an inclined surface arrangement on a lens substrate.
9 is a cross-sectional view taken along line AA ′ of FIG.
10 is a cross-sectional view taken along line BB ′ of FIG.
FIG. 11 is a cross-sectional view showing a Cu / Cr lamination forming process in the bar juxtaposition plate making method according to the present invention.
12 is a cross-sectional view showing a resist layer forming step that follows the step of FIG. 11. FIG.
13 is a plan view showing a resist layer formed in the step of FIG.
FIG. 14 is a cross-sectional view showing a selective plating step following the step of FIG.
15 is a cross-sectional view showing a resist removing step that follows the step of FIG. 14;
16 is a cross-sectional view showing a bar juxtaposed plate separating step subsequent to the step of FIG.
[Explanation of symbols]
10: juxtaposed plate holder, 10a to 10c: juxtaposed plate insertion groove, 12a to 12c, 12: bar juxtaposed plate, 14: fixed substrate, 16: adhesive layer, 18: lens substrate, 20: replica material layer, 30: quartz Substrate, 32: Cr layer, 34: Cu layer, 36: Resist layer, 36A: Plating hole, R _{1 to} R ₇ , R _{11 to} R ₁₇ , R _{21 to} R ₂₇ , R _{31 to} R ₃₇ , R _{41 to} R _47: inclined _surface, B 1 .about.B _7: quartz _bar, L 11 _{~L 71: lens,} F 11 _{to F 14:} optical fiber.

Claims (2)

A step of creating a plurality of metal bar juxtaposed plates with a plurality of inclined surfaces in a sawtooth shape along one side in the length direction by a thin film process,
A step of holding the plurality of bar juxtaposed plates side by side so that the inclined surface positions are aligned in a direction perpendicular to the length direction of the bar juxtaposed plate with each inclined surface facing upward;
The step of arranging a plurality of prismatic bars on top of the plurality of bar juxtaposed plates by arranging a prismatic bar for each set of inclined surfaces aligned in a state where the plurality of bar juxtaposing plates are held side by side. When,
In a state where the plurality of prismatic bars are juxtaposed above the plurality of bar juxtaposed plates, the plurality of prismatic bars are bonded and fixed to a fixed substrate on the side opposite to the plurality of bar juxtaposed plates. Process,
In a state where the plurality of prismatic bars are fixed to the fixed substrate, the plurality of prismatic bars are saw-toothed on the side opposite to the fixed side by separating from the upper portions of the plurality of bar juxtaposed plates. A step of exposing the inclined surface chain pattern linked in a shape;
In a lens substrate having a plurality of lenses formed on one main surface, the inclined surface chain pattern of the plurality of prismatic bars is formed on the replica material layer formed on the other main surface, and the plurality of inclined surfaces are the plurality of lenses. And a process of transferring so as to face each other,
The inclined surface chain pattern transferred to the replica material layer is transferred to the other main surface of the lens substrate by an etching process so that the plurality of inclined surfaces are opposed to the plurality of lenses, respectively. A method of forming an inclined surface of a microlens array including a step of forming on a surface. A lens in a matrix arrangement is formed as the plurality of lenses on one main surface of the lens substrate. In the step of transferring the inclined surface chain pattern of the plurality of prismatic bars to the replica material layer, a plurality of lenses are arranged. In the step of transferring the inclined surface so as to face the plurality of lens rows (or lens columns) of the lens substrate, respectively, and transferring the inclined surface chain pattern of the replica material layer to the other main surface of the lens substrate, 2. The method of forming an inclined surface of a microlens array according to claim 1, wherein a plurality of inclined surfaces are formed so as to face a plurality of lens rows (or lens columns) of the lens substrate.

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