JP2014089230A - Microlens array manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microlens array manufacturing method which enables manufacturing of a highly light resistant microlens array and provides high molding accuracy in the manufacturing process.SOLUTION: A method of manufacturing a microlens array includes the steps of; forming a plurality of lenticular recesses 21 on an upper surface of a light transmissive substrate 2; forming a first inorganic layer 34, which is light transmissive and has a higher refractive index than the substrate at least at an interface with the substrate, by filling the lenticular recesses and covering the upper surface with a light transmissive inorganic material to a level above the upper surface; forming a mask 5 having a shape corresponding to the plurality of lenticular recesses on a surface of the first inorganic layer using a photolithographic method and etching the first inorganic layer via the mask to form a plurality of lenses which overlaps one on one with the plurality of lenticular recesses in a planar view; and forming a second light transmissive inorganic layer which covers at least the surfaces of the plurality of lenses.

Description

  The present invention relates to a method for manufacturing a microlens array.

Conventionally, a microlens array in which a plurality of microlenses are arranged on a substrate is known. The microlens array is, for example, disposed between a light source and a liquid crystal light valve in a liquid crystal projector to suppress loss of light amount, disposed on a solid-state imaging device, to increase incident light, or communication means using an optical fiber Are used for many purposes, such as effectively allowing a signal to enter the optical fiber.

Such a microlens array is, for example, filling a transparent substrate with transparent substrates each having a plurality of recesses, and further stacking transparent substrates having recesses or projections that are paired with each recess,
It can be formed by sandwiching a transparent resin between transparent substrates. Each transparent substrate is bonded with an adhesive material (resin) containing a spacer. The transparent resin sealed between the concave portions of each transparent substrate or between the concave portions and the convex portions forms a plurality of microlenses (for example, see Patent Documents 1 and 2).

Japanese Patent Laid-Open No. 2002-14205 Japanese Patent Laid-Open No. 2002-6115

However, the microlens array obtained by the above method has low light resistance because the lens is resinous. In addition, the separation distance between the pair of transparent substrates (that is, the separation distance of the lens surface forming the microlens) is controlled by a spherical spacer disposed between the substrates. The distance may be affected, and it may be difficult to maintain the design value. Further, since the transparent resins are bonded with resin, it is difficult to obtain the position accuracy of the bonding position of the transparent substrate due to volume deformation when the resin is cured.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for manufacturing a microlens array having high light resistance and high molding accuracy (positional accuracy) during manufacturing.

In order to solve the above problems, one embodiment of the present invention includes a step of forming a plurality of lens-shaped depressions on an upper surface of a light-transmitting substrate and filling the lens-shaped depressions with a light-transmitting inorganic material. And a step of forming a first inorganic layer that covers the upper surface and is laminated above the upper surface, has a light transmittance, and has a refractive index higher than that of the substrate at least at the interface with the substrate; Using a lithography method, a mask corresponding to the plurality of lens-shaped recesses is formed on the surface of the first inorganic layer, the first inorganic layer is etched through the mask, and the plurality of lens-shaped recesses Forming a lens having a plurality of lenses that are one-to-one and planarly overlapped with each of the first and second lenses, covering at least the surface of the lens and having optical transparency.
And a step of forming an inorganic layer.

The first inorganic layer formed on the substrate becomes a plurality of lenses (hereinafter referred to as first lenses) corresponding to the lens-shaped concave portions of the substrate on the substrate side. Also, on the opposite side of the first inorganic layer from the substrate,
A plurality of lenses (hereinafter referred to as second lenses) are formed. As a result, a plurality of microlenses having a first lens and a second lens using an inorganic material, that is, a microlens array is formed. Since the obtained microlens array uses an inorganic material as a forming material, it has high light resistance.

Further, the distance between the first lens and the second lens can be easily controlled by controlling the thickness of the first inorganic layer.

Furthermore, since the resin material is not included in the microlens, there is no possibility of displacement due to the volume change of the resin.

Therefore, according to this method, it is possible to provide a method for manufacturing a microlens array having high light resistance and high molding accuracy during manufacturing.

In one aspect of the present invention, it is preferable to have a step of planarizing the surface of the first inorganic layer prior to the step of forming the plurality of lenses.
According to this configuration, since a plurality of lenses can be formed with high dimensional accuracy, a high-quality microlens array can be manufactured.

In one aspect of the present invention, it is preferable to have a step of flattening the surface of the second inorganic layer after the step of forming the second inorganic layer.
According to this configuration, it is possible to manufacture a high-quality microlens array while suppressing irregular reflection and refraction disturbance on the surface.

In one aspect of the present invention, in the step of laminating the first inorganic layer, after filling at least the lens-shaped recess using a first inorganic material that has optical transparency and a higher refractive index than the substrate. It is preferable to laminate a second inorganic material that covers the upper surface and has optical transparency.
According to this configuration, since the first lens can be formed by filling the lens-shaped concave portion with the first inorganic material and then laminated using the second inorganic material, the degree of design freedom increases. For example, the manufacturing time can be shortened by selecting a material that is easier to stack than the first inorganic material as the second inorganic material.

In one aspect of the present invention, at the interface between the plurality of lenses and the second inorganic layer, the plurality of lenses have a higher refractive index than the second inorganic layer, and the shape of the plurality of lenses is convex. The shape is preferred.
According to this configuration, a microlens array having a light condensing function can be easily manufactured.

In one aspect of the present invention, at the interface between the plurality of lenses and the second inorganic layer, the plurality of lenses have a higher refractive index than the second inorganic layer, and the shape of the plurality of lenses is concave. The shape is preferred.
According to this configuration, a microlens array having an effect of reducing the line width of the light beam can be easily manufactured.

It is explanatory drawing of the micro lens array manufactured with the manufacturing method of 1st Embodiment. It is a figure which shows the usage example of the micro lens array manufactured by 1st Embodiment. It is process drawing which shows the manufacturing method of the micro lens array of 1st Embodiment. It is process drawing which shows the manufacturing method of the micro lens array of 1st Embodiment. It is process drawing which shows the manufacturing method of the micro lens array of 1st Embodiment. It is process drawing which shows the manufacturing method of the micro lens array of 1st Embodiment. It is explanatory drawing of the micro lens array manufactured with the manufacturing method of 2nd Embodiment. It is process drawing which shows the manufacturing method of the micro lens array of 2nd Embodiment. It is process drawing which shows the manufacturing method of the micro lens array of 2nd Embodiment. It is process drawing which shows the manufacturing method of the micro lens array of 2nd Embodiment. It is explanatory drawing which shows the microlens array of a modification. It is explanatory drawing which shows the process of manufacturing several micro lens array.

[First Embodiment]
Hereinafter, a method for manufacturing a microlens array according to the first embodiment of the present invention will be described with reference to FIGS. In all the drawings below, the dimensions and ratios of the constituent elements are appropriately changed in order to make the drawings easy to see.

FIG. 1 is an explanatory view showing a microlens array manufactured by the method for manufacturing a microlens array of the present embodiment. 1 (a) is a schematic perspective view, (b) is a plan view, and (c) is (a).
It is arrow sectional drawing in line segment AA.

As shown in FIGS. 1A to 1C, the microlens array 1A includes a substrate 2, a lens layer 3 having a plurality of microlenses 31, and an inorganic layer (second layer) provided so as to cover the lens layer 3. Inorganic layer) 4 is provided.

The substrate 2 has a plurality of concave portions (lens-shaped concave portions) 21 corresponding to the plurality of microlenses 31, and a material for forming the plurality of microlenses 31 is fixed inside the lens-shaped concave portions 21 to form the microlenses 31. ing.

The substrate 2 is made of an inorganic material having high heat resistance and light resistance. For example, substrate 2
As a quartz glass substrate having a high light transmittance (refractive index (589.3 nm): 1.46)
) Or neo-serum glass substrate (refractive index (589.3 nm): 1.54) is preferably used.

The lens layer 3 has optical transparency and has a refractive index higher than that of the substrate 2 at least at the interface between the microlens 31 and the substrate 2 included in the lens layer 3. In the present embodiment, the entire lens layer 3 has a higher refractive index than the substrate 2. The lens layer 3 is made of, for example, Al ₂ O
₃ (refractive index (589.3 nm): 1.77) or an inorganic material such as SiON. SiON is composed of SiO ₂ (refractive index (589.3 nm): n = 1.46) and Si ₃ N ₄ (refractive index (58) depending on the composition (ratio) of oxygen atoms (O) and nitrogen atoms (N).
9.3 nm): n = 2.00).

The second inorganic layer 4 is made of an inorganic material having optical transparency. For example, the second inorganic layer 4 can be made of SiO ₂ or SiON.

The plurality of microlenses 31 have a biconvex shape having convex shapes in both the light incident direction and the light emitting direction. The adjacent microlenses 31 are in contact with each other in a plan view and have a rectangular shape in plan view. A plurality of such microlenses 31 are arranged in a matrix to form a lens portion 32.

The microlens 31 includes a first lens 31a that is fixed to the substrate 2, a second lens 31b that is a portion covered with the second inorganic layer 4, and a space between the first lens 31a and the second lens 31b. The optical path length adjusting layer 31c is disposed. The optical path length adjustment layer includes the first lens 31a.
This is a layer for adjusting the optical path length between the first lens 31b and the second lens 31b.

2A and 2B are schematic views showing an example of use of the microlens array 1A manufactured by the manufacturing method of the microlens array of the present embodiment, FIG. 2A is a plan view, and FIG. 2B is a line segment B- It is arrow sectional drawing in B. In the figure, the microlens array 1A is connected to the color filter substrate CF.
And a state of being further bonded to the liquid crystal light valve LV.

As shown in FIG. 2A, the microlens 31 has a rectangular shape in plan view similar to the plan view shape of the black matrix BM included in the color filter substrate CF, and the boundary line between adjacent microlenses 31 is black. The matrix BM is arranged so as to overlap with the plane.

As shown in FIG. 2 (b), the microlens array 1A uses light L1 incident from the outside on the substrate 2 side, the interface between the substrate 2 and the microlens 31, and the microlens 31 and the second inorganic layer 4. Refract at the interface. Furthermore, the microlens array 1A is adjusted via the color filter substrate CF by adjusting the optical path length adjusting layer 31c and the second inorganic layer 4 included in the microlens 31 so that the focal point of the microlens 31 is at the optimum position. Light L
1 enters the liquid crystal light valve LV.

Of course, the configuration shown in FIG. 2 is an example. For example, the microlens array 1A may be directly bonded to the liquid crystal light valve LV without using the color filter substrate CF.

Next, the manufacturing method of the microlens array of this embodiment is demonstrated using FIGS.

FIG. 3 shows a process of forming a plurality of lens-shaped recesses in this embodiment.
First, as shown in FIG. 3A, a glass substrate 20 having a uniform thickness, no scratches, and a quartz glass or neo-ceram glass whose surface is cleaned is prepared, and the surface of the glass substrate 20 is prepared. A mask forming film 22 is formed.

The mask forming film 22 functions as a mask by forming an opening (initial hole) in a later step. As will be described later, an initial hole 23 is formed in the mask forming film 22 by laser irradiation, and then a recess is formed in the glass substrate 20 from the initial hole 23 by etching. Therefore, the mask forming film 22 is preferably resistant to etching. That is, the etching rate of the mask forming film 22 is sufficiently smaller than that of the glass substrate 20.

Therefore, as the material of the mask forming film 22, for example, a metal such as Cr, Au, Ni, or Pt, or an alloy containing two or more selected from these, an oxide such as Cr, Au, Ni, or Pt is used. (Metal oxide), silicon, resin and the like are used. Moreover, it is good also as a several laminated structure which consists of a different material like Cu and Au or oxide Cr and Cr. The method for forming the mask forming film 22 is not particularly limited, and includes vapor deposition, sputtering, and CV.
The optimum method for the film material is appropriately selected and used from the D method (Chemical Vapor Deposition). The film thickness is appropriately set according to the initial hole formation conditions and etching conditions, but is preferably about 0.01 μm to 0.2 μm.

Next, as shown in FIG. 3B, an initial hole 23 is formed at the position where the lens-shaped recess is formed in the mask forming film 22 to obtain a mask 24 having a predetermined opening pattern. Initial hole 23
As the forming method, laser light irradiation, etching treatment or the like is employed. In particular, high positional accuracy can be maintained, and the interval between the adjacent initial holes 23 can be accurately controlled. Therefore, laser beam irradiation is preferably employed.

Next, as shown in FIG. 3C, the lens-shaped recess 21 is formed in the glass substrate 20 by etching through the initial hole 23 formed in the mask 24. In the present embodiment, the lens-shaped recess 21 is formed by wet etching. Although the etching solution is not particularly limited, in this embodiment, since the glass substrate 20 is used as the substrate, an etching solution (hydrofluoric acid-based etching solution) containing hydrofluoric acid (hydrogen fluoride) is preferably used. By using a hydrofluoric acid-based etching solution, the glass substrate 20 can be etched more selectively, and the lens-shaped recess 21 can be suitably formed.

The glass substrate 2 is etched by etching the glass substrate 20 covered with the mask 24.
0 is isotropically etched from the initial hole 23 formed in the mask 24 with an etching solution, and the lens-shaped recess 21 is formed.

By controlling the etching time and the like, the lens-shaped recess 21 having a predetermined depth can be formed as shown in FIG. In addition, about this lens-shaped recessed part 21, in order to make the thickness of the microlens formed thin, it is preferable to make the depth as shallow as possible. Therefore, in this embodiment, the lens-shaped recess 21 is formed in a hemispherical shape so that its depth is about the radius of the hemisphere.

Next, as shown in FIG. 3E, the mask 24 is removed by etching or the like to obtain the substrate 2 having a plurality of lens-shaped recesses 21 on the upper surface 2a.

FIG. 4 shows a step of forming the first inorganic layer in the present embodiment.
As shown in FIG. 4A, the first inorganic layer 33 is formed by laminating a light-transmitting inorganic material on the upper surface 2 a of the substrate 2. The first inorganic layer 33 includes a plurality of lens-shaped recesses 2 provided on the substrate 2.
1, and is further laminated so as to cover the upper surface 2 a of the substrate 2 and above the upper surface 2 a. The 1st inorganic layer 33 with which the lens-shaped recessed part 21 was filled becomes the 1st lens 31a.

Such a first inorganic layer 33 has a refractive index higher than that of the substrate 2 at least at the interface with the substrate 2. As the material for forming the first inorganic layer 33, the above-described materials can be used as the material for forming the lens layer 3 shown in FIG.

As a method for forming the first inorganic layer 33, either a dry method or a wet method can be employed. As the dry method, a physical vapor deposition method such as CVD, sputtering or EB (electron beam) vapor deposition can be suitably used. As a wet method, SOG (Spin On Glas
s) or a method in which a glass frit dispersion is applied and then baked for formation.

Further, as shown in FIG. 4B, the surface of the first inorganic layer (a layer obtained by laminating inorganic materials) 33 is flattened to obtain a first inorganic layer 34 having a flattened surface 34a. It is preferable. As the planarization treatment, CMP (Chemical Mechanical Polishing) or etching can be employed.

Of course, if the surface of the first inorganic layer 33 obtained in the process of FIG. 4A is sufficiently flat with respect to the requirements of design and processing accuracy, the planarization process may not be performed.

By performing such an operation, a plurality of lenses can be formed with high dimensional accuracy in a subsequent manufacturing process, and thus a high-quality microlens array can be manufactured.
In the following description, it is assumed that a target microlens array is manufactured using the first inorganic layer 34 subjected to the surface planarization process.

Further, the thickness of the first inorganic layer 34 can be controlled by the planarization process. The thickness of the first inorganic layer 34 can be controlled according to the design of the microlens 31 to be formed, and is, for example, 10 μm to 100 μm.

FIG. 5 shows a process of forming a plurality of lenses in the present embodiment.
As shown in FIG. 5A, the surface 3 of the first inorganic layer 34 is formed by photolithography.
A mask 5 corresponding to the plurality of lens-shaped recesses 21 is formed on 4a. In FIG. 5A, the mask 5 having a convex shape is formed.

Such a mask 5 is, for example, coated with a positive photoresist, exposed and developed through a photomask having an opening pattern at a position overlapping the boundary portions of the plurality of lens-shaped recesses 21, and then the softening temperature of the remaining photoresist. The substrate 2, the first inorganic layer 34, and the photoresist can be heated up to the above.

Next, as shown in FIG. 5B, the shape of the mask 5 is transferred to the first inorganic layer 34 by anisotropic dry etching and etch back, thereby forming the second lens 31b. First inorganic layer 34
In the thickness direction, the portion where the second lens 31b is not formed is the optical path length adjusting layer 31c.
It becomes. Thus, the lens layer 3 is obtained by forming the second lens 31b and the optical path length adjustment layer 31c and forming the lens portion 32 having the plurality of microlenses 31. Examples of the etching gas E1 used for dry etching include CF ₄ , CHF ₃ , and C _2.
Fluorine-containing gases such as F ₆ and SF ₆ can be used.

Alternatively, the method of forming the mask 5 does not use the softening of the photoresist as described above, but forms a stepwise mask in cross section by laminating a layered resist layer that gradually decreases in plan view. It is good as well. Even when the microlens 31 is formed by dry etching using such a mask, the stepped corners of the mask are gently leveled in the etch back process, and a desired lens shape can be formed. Is possible.

FIG. 6 shows a step of forming the second inorganic layer in the present embodiment.
As shown in FIG. 6A, the surface 3a of the lens layer 3 is covered (covering the surfaces of the plurality of second lenses 31b), an optically transparent inorganic material is laminated, and the second inorganic layer 41 is formed. Form. Second
As the material for forming the inorganic layer 41, the materials described above as the material for forming the second inorganic layer 4 shown in FIG. 1 can be used. As a method of forming the second inorganic layer 41, the first inorganic layer 3 described above is used.
A method similar to the method of forming 3 can be employed.

Further, as shown in FIG. 6B, the surface of the second inorganic layer (layer obtained by laminating the material for forming the second inorganic layer) 41 is planarized, and the second surface 4a is planarized. The inorganic layer 4 is preferable. As the planarization treatment, CMP or etching can be employed. By performing such an operation, irregular reflection of light and refraction disturbance on the surface 4a can be suppressed, and a high-quality microlens array can be manufactured.

Of course, if the surface of the second inorganic layer 41 obtained in the process of FIG. 6A is sufficiently flat with respect to the design requirements, the planarization process may not be performed. Further, the thickness of the second inorganic layer 4 can be controlled by the planarization treatment. Thereby, the distance from the surface 4a to the focal position of the microlens 31 can be controlled, and light can be condensed at a desired position in a member such as a liquid crystal light valve provided on the surface 4a.
As described above, the microlens array 1A can be manufactured by carrying out the method for manufacturing the microlens array of the present embodiment.

According to the method for manufacturing a microlens array having the above-described configuration, the microlens 31 manufactured using the first inorganic layer 34 has high light resistance because it uses an inorganic material as a forming material.

Further, by controlling the layer thickness of the first inorganic layer 34, the separation distance between the first lens 31a and the second lens 31b (that is, the thickness of the optical path length adjusting layer 31c) can be easily controlled.

Further, since the resin material is not included in the microlens 31, there is no possibility of positional displacement due to the volume change of the resin.

Therefore, the microlens array 1A having high light resistance and high molding accuracy at the time of manufacture can be manufactured.

In the present embodiment, the planar view shape of the microlens 31 included in the manufactured microlens array 1A is rectangular. However, the shape is not limited to this, and the adjacent microlenses 31 are not in contact with each other. It does not matter as being. Such a microlens array can be manufactured, for example, by ending etching in the state shown in FIG. 3C in the etching shown in FIG. In this case, the microlens 3
The shape of 1 in plan view is substantially circular.

[Second Embodiment]
FIGS. 7-10 is explanatory drawing of the manufacturing method of the microlens array which concerns on 2nd Embodiment of this invention. Since the microlens array 1B manufactured in the present embodiment is partly in common with the microlens array 1A manufactured in the first embodiment, the same components in the present embodiment as in the first embodiment are the same. Reference numerals are assigned and detailed description is omitted.

FIG. 7 is an explanatory view showing a microlens array 1B manufactured by the method for manufacturing a microlens array of the present embodiment. Fig.7 (a) is a schematic perspective view, and is a figure corresponding to Fig.1 (a). FIG. 7B is a cross-sectional view taken along line CC in FIG. 7A and corresponds to FIG. FIG.7 (c) is a figure explaining an effect | action and is a figure corresponding to FIG.2 (b).

As shown in FIGS. 7A and 7B, the microlens array 1B includes a substrate 2, a lens layer 6 having a plurality of microlenses 61, and an inorganic layer (second inorganic layer) provided so as to cover the lens layer 6. Layer) 7.

The substrate 2 has a plurality of concave portions (lens-shaped concave portions) 21 corresponding to the plurality of microlenses 61, and the forming material of the plurality of microlenses 61 is fixed inside the lens-shaped concave portions 21 to form the microlenses 61. ing.

The lens layer 6 is light transmissive and has a refractive index higher than that of the substrate 2 at least at the interface between the microlens 61 and the substrate 2 included in the lens layer 6. As the material for forming the lens layer 6, the same material as the material for forming the lens layer 3 of the first embodiment can be used.

The second inorganic layer 7 is made of an inorganic material having optical transparency. For example, the second inorganic layer 7 can be made of SiO ₂ or SiON.

The plurality of microlenses 61 is the substrate 2 as viewed from the center side in the thickness direction of the microlens 61.
This is a so-called meniscus lens having a convex shape on the side and a concave shape on the second inorganic layer 7 side. The adjacent microlenses 61 are in contact with each other in a plan view and have a rectangular shape in plan view. A plurality of such microlenses 61 are arranged in a matrix to form a lens unit 62.

The micro lens 61 is a first lens 61 a that is fixed to the substrate 2 and a second lens 61 b that is a portion covered with the second inorganic layer 7 and is a recess filled with the second inorganic layer 7. The optical path length adjusting layer 61c is sandwiched between the first lens 61a and the second lens 61b.

As shown in FIG. 7C, the microlens array 1 </ b> B transmits light L <b> 2 incident from the outside on the substrate 2 side, the interface between the substrate 2 and the microlens 61, and the microlens 61 and the second inorganic layer 7. The light beam is refracted at the interface to converge the light flux. That is, the code L
When the width of the light bundle of the light L2 indicated by a is compared with the width of the light bundle indicated by the reference Lb, a relationship of La> Lb is established. In such a microlens array 1B, by controlling the thickness of the optical path length adjusting layer 61c included in the microlens 61, the width Lb of the converged light bundle is adjusted to be optimal, and the light L2 is converted into a liquid crystal light. The light enters the valve LV.

Next, the manufacturing method of the microlens array of this embodiment is demonstrated using FIGS.

FIG. 8 shows a step of forming the first inorganic layer in the present embodiment.
First, as shown in FIG. 8A, an upper surface 2a of a substrate 2 formed by the method shown in FIG. 3 of the first embodiment (step of forming a plurality of lens-shaped recesses) is the same as that of the first embodiment. In addition, a first inorganic layer 63 is formed by laminating a light-transmitting inorganic material. The first inorganic layer 63 is formed by filling the plurality of lens-shaped concave portions 21 provided on the substrate 2 and further stacking the upper surface 2a of the substrate 2 to the upper side of the upper surface 2a. The 1st inorganic layer 63 with which the lens-shaped recessed part 21 was filled becomes the 1st lens 61a.

Such a first inorganic layer 63 has a refractive index higher than that of the substrate 2 at least at the interface with the substrate 2. As a material for forming the first inorganic layer 63, the materials described above can be used as the material for forming the lens layer 6 shown in FIG.

As a method of forming the first inorganic layer 63, a method similar to the method of forming the first inorganic layer 33 of the first embodiment can be employed.

Further, as shown in FIG. 8B, a first inorganic layer (a layer obtained by laminating inorganic materials) 63
It is preferable to perform the surface flattening process of the first inorganic layer 64 with the surface 64a flattened. As the planarization treatment, CMP or etching can be employed.

Of course, if the surface of the first inorganic layer 63 obtained in the step of FIG. 8A is sufficiently flat with respect to the requirements of design and processing accuracy, the planarization process may not be performed.

By performing such an operation, a plurality of lenses can be formed with high dimensional accuracy in a subsequent manufacturing process, and thus a high-quality microlens array can be manufactured.
In the following description, it is assumed that a target microlens array is manufactured using the first inorganic layer 64 that has been subjected to surface planarization. Further, the first inorganic layer 6 is obtained by the planarization process.
The thickness of 4 can be controlled.

FIG. 9 shows a process of forming a plurality of lenses in the present embodiment.
As shown in FIG. 9A, a mask 82 having initial holes 81 at positions corresponding to the plurality of lens-shaped recesses 21 is formed on the surface 64 a of the first inorganic layer 64. As a forming material of the mask 82 and a processing method of the initial hole 81, the same material and method as those of the mask 24 shown in FIG. 3 of the first embodiment can be adopted.

Next, as shown in FIG. 9B, the first inorganic layer 64 is etched by etching through the initial hole 81 formed in the mask 82, thereby forming the second lens 61b. In this embodiment,
The second lens 61b is formed by wet etching. In the thickness direction of the first inorganic layer 64, the portion where the second lens 61b is not formed becomes the optical path length adjustment layer 61c. Thus, the lens layer 6 is obtained by forming the second lens 61b and the optical path length adjusting layer 61c and forming the lens portion 62 having the plurality of microlenses 61. Etching solution E
As 2, the fluorine-based etching solution is preferably used.

FIG. 10 shows a step of forming the second inorganic layer in the present embodiment.
As shown in FIG. 10A, the surface 6a of the lens layer 6 is covered (a plurality of second lenses 61b).
The second inorganic layer 71 is formed by laminating a light-transmitting inorganic material. As a material for forming the second inorganic layer 71, the materials described above can be used as the material for forming the second inorganic layer 7 shown in FIG. As a method of forming the second inorganic layer 71, a method similar to the method of forming the first inorganic layer 63 described above can be employed.

Further, as shown in FIG. 10B, the surface of the second inorganic layer (layer obtained by laminating the material for forming the second inorganic layer) 71 is flattened, and the second surface 7a is flattened. The inorganic layer 7 is preferable. As the planarization treatment, CMP or etching can be employed. By performing such an operation, irregular reflection of light and refraction disturbance on the surface 7a can be suppressed, and a high-quality microlens array 1B can be manufactured.

Of course, if the surface of the second inorganic layer 71 obtained in the step of FIG. 10A is sufficiently flat with respect to the design requirements, the planarization process may not be performed.

Further, the thickness of the second inorganic layer 7 can be controlled by the planarization process. Thereby, the lens tip distance between the first lens 61a and the second lens 61b (indicated by symbol a in the figure),
It is possible to control the relationship between the distance between the second lens 61b and the surface 7a of the second inorganic layer 7 (indicated by symbol b in the figure).

That is, in the microlens array 1B manufactured by the microlens array manufacturing method of the present embodiment, it is preferable that the distance a and the distance b have a relationship represented by b <a. Furthermore, the distance b is preferably 1 μm or more and 10 μm or less. By setting the distance b to 10 μm or less, a thin microlens array can be obtained.

As described above, the microlens array 1B can be manufactured by implementing the method of manufacturing the microlens array of the present embodiment.

The microlens array 1B having high light resistance and high molding accuracy at the time of manufacture can also be manufactured by the method for manufacturing a microlens array having the above configuration.

The preferred embodiment of the present invention has been described above with reference to the accompanying drawings.
It goes without saying that the present invention is not limited to such examples. Various shapes, combinations, and the like of the constituent members shown in the above-described examples are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

[Modification]
For example, in the first embodiment, the first inorganic layer 34 is illustrated and described as being formed of a single forming material, but has a refractive index higher than that of the substrate 2 at least at the interface with the substrate 2. If so, a plurality of forming materials may be stacked. FIG.
It is explanatory drawing which shows the microlens array of a modification, and is a figure corresponding to FIG.1 (c) of 1st Embodiment.

In the microlens array 1C shown in FIG. 11A, the lens layer 9A having the microlens 91 is formed by laminating a first layer 9a and a second layer 9b.

The first layer 9 a is formed using a first inorganic material that is light transmissive and has a higher refractive index than the substrate 2. The first layer 9a fills the lens-shaped recess 21 of the substrate 2 and forms the first lens 91a.

The second layer 9b is laminated so as to cover the upper surface of the first layer 9a using a second inorganic material having optical transparency. The second layer 9b forms a second lens 91b and an optical path length adjustment layer 91c.

The microlens array having such a structure first fills at least the lens-shaped concave portion 21 with a first inorganic material having optical transparency and a higher refractive index than that of the substrate 2, and then covers the upper surface of the substrate 2. By laminating the second inorganic material having light transmittance, a first inorganic layer in which the first inorganic material and the second inorganic material are laminated is formed. Thereafter, the second lens 91b can be formed by dry etching by the method shown in the first embodiment.

In the microlens array 1D shown in FIG. 11B, the lens layer 9B having the microlens 92 is formed by laminating a first layer 9a, a second layer 9c, and a third layer 9d.

The first layer 9a is the same as the first layer 9a in FIG. 11A, and forms the first lens 92a.

The second layer 9c is laminated so as to cover the upper surface of the first layer 9a using a light-transmitting second inorganic material, thereby forming an optical path length adjusting layer 92c.

The third layer 9d is laminated so as to cover the upper surface of the second layer 9c using a third inorganic material having optical transparency, thereby forming a second lens 92b.

The microlens array having such a structure first fills at least the lens-shaped concave portion 21 with a first inorganic material having optical transparency and a higher refractive index than that of the substrate 2, and then covers the upper surface of the substrate 2. By laminating the second inorganic material and the third inorganic material having light transmittance,
A first inorganic layer in which the first to third inorganic materials are stacked is formed. Then, after forming the 1st inorganic layer which laminated | stacked the 1st-3rd inorganic material, it can manufacture by dry-etching by the method shown in 1st Embodiment, and forming the 2nd lens 92b.

When forming a plurality of layers constituting the first inorganic layer, the surface may be planarized before forming the layers made of different materials. Further, when the microlens array 1D shown in FIG. 11B is manufactured, the first layer 9a and the substrate 2 are shaved by a planarization process performed before the formation of the second layer 9c. It is good also as separating the adjacent lens-shaped recessed part 21 (1st lens 92a).

As described above, when a plurality of layers are stacked using a plurality of different materials to form the first inorganic layer, the degree of freedom in designing the microlens array is increased. For example, by selecting a material that is easier to stack than the first inorganic material as the second inorganic material, the manufacturing time of the layer corresponding to the optical path length adjusting layer can be shortened.

In addition, when a plurality of layers are laminated using a plurality of different materials to form the first inorganic layer, a compressive stress is applied to the substrate 2 in a direction perpendicular to the normal direction of the substrate 2 as the formed layer. The inorganic layer (first inorganic layer) that expresses and the inorganic layer (second inorganic layer) that expresses tensile stress in a direction perpendicular to the normal direction of the substrate 2 with respect to the substrate 2 are alternately laminated. It is good to do.

When manufacturing a laminate (microlens array) formed by stacking different materials as in the microlens array manufacturing method of the present embodiment, for example, heating of the substrate inevitably generated during the formation of the inorganic film, The laminated body may be warped due to a difference in thermal expansion coefficient of each layer due to a difference in formation material or thickness of each layer to be laminated.

Therefore, when a plurality of layers are stacked using a plurality of different materials to form the first inorganic layer, a stress that warps the substrate 2 in a direction that cancels the warp of the substrate 2 forming the first inorganic layer is applied. The film to be expressed may be selected from the first inorganic layer and the second inorganic layer and stacked on the substrate 2.

Alternatively, even when the substrate 2 is not warped, when warping occurs by forming one of the plurality of layers constituting the first inorganic layer on the substrate 2, the warping that has occurred is offset. A layer that develops stress that warps the substrate 2 may be selected from the first inorganic layer and the second inorganic layer described above.

For example, the first inorganic layer and the second inorganic layer may be formed by plasma CVD using silicon oxide (SiO ₂ ).
When the film is formed in (1), it can be made by selecting either the high-frequency plasma source or the low-frequency plasma source. Specifically, using a high-frequency plasma source, the resulting SiO
_{The first} film becomes rough, and a first inorganic layer that expresses compressive stress in a direction perpendicular to the normal direction of the substrate 2 with respect to the substrate 2 is obtained. When a low frequency plasma source is used, the resulting SiO ₂ film becomes dense, and a second inorganic layer that exhibits tensile stress in a direction perpendicular to the normal direction of the substrate 2 with respect to the substrate 2 is obtained.

In the above-described embodiments, the process of manufacturing one microlens array has been described. However, the present invention is not limited to this, and a plurality of lens portions are formed on a large glass substrate and then divided. Thus, a microlens array may be manufactured. FIG.
FIG. 2 is an explanatory diagram showing a process of manufacturing a plurality of microlens arrays by multiple chamfering.

For example, as shown in FIG. 12 (a), in the large glass substrate 120, the step of forming the plurality of lens-shaped recesses described above, the step of forming the first inorganic layer, and the step of forming the plurality of lens portions, By performing the process at a plurality of positions, the lens layer 130 in which a plurality of (four positions in the figure) lens portions 32 are formed is formed.

Next, as shown in FIG. 12B, the second inorganic layer 140 covers the surface of the lens layer 130.
To form the original plate 100 on which four microlens arrays 1A are formed.

Thereafter, the four microlens arrays 1A can be manufactured by dividing into four along the dividing line indicated by the symbol X.

12 shows a configuration in which the four lens portions 32 that are spaced apart from each other are formed on the glass substrate 120. However, the present invention is not limited to this, and the lens portion 32 is formed on the entire upper surface of the glass substrate 120. After the microlens array is formed, it may be divided into a predetermined size. According to such a method, in the macro lens array unit obtained after the division, there are locations where microlenses are formed (hereinafter, formation regions) and locations where microlenses are not formed (hereinafter, non-formation regions). There is no mixing. For this reason, the shape of the microlens is not affected by the fluctuation in processing accuracy at the boundary between the non-formation region and the formation region, and a plurality of microlenses can be formed with high accuracy up to the end of the microlens array. .

When the microlens array is formed after the microlens array original plate 100 is manufactured, an alignment mark used for alignment for forming the microlens is preferably formed in a non-formation region. Such an alignment mark may be formed at a position where it disappears at the time of division, or may remain in a non-formation region of the obtained microlens array.

1A, 1B, 1C, 1D ... micro lens array, 2 ... substrate, 2a ... upper surface, 3a, 4a
, 6a, 7a, 34a, 64a ... surface, 4, 7, 31, 41, 71, 140 ... second inorganic layer, 4, 7 ... inorganic layer, 4, 7 ... inorganic layer (second inorganic layer), 5, 24, 82 ... mask, 21 ... lenticular recess, 21 ... recess (lens-like recess), 31, 61, 91, 92 ... microlens,
33, 34, 63, 64 ... first inorganic layer, 41, 71 ... second inorganic layer (a layer obtained by laminating the forming material of the second inorganic layer), L1, L2 ... light

Claims (6)

Forming a plurality of lens-shaped recesses on the upper surface of the substrate having light transparency;
An optically transparent inorganic material is filled in the lens-shaped recess and is laminated to cover the upper surface and above the upper surface so as to have light transmittance and at least at the interface with the substrate is higher than the substrate. Forming a first inorganic layer having a refractive index;
Using a photolithography method, a mask corresponding to the plurality of lens-shaped recesses is formed on the surface of the first inorganic layer, and the first inorganic layer is etched through the mask to form the plurality of lens-shaped Forming a plurality of lenses planarly overlapping with each of the recesses in a one-to-one correspondence;
Forming a second inorganic layer having light permeability so as to cover at least the surfaces of the plurality of lenses. 2. The method of manufacturing a microlens array according to claim 1, wherein in the step of forming the first inorganic layer, a surface of a layer obtained by laminating a material for forming the first inorganic layer is flattened. 3. The method for manufacturing a microlens array according to claim 1, wherein in the step of forming the second inorganic layer, a surface of a layer obtained by laminating the material for forming the second inorganic layer is planarized. In the step of forming the first inorganic layer, at least the lens-shaped concave portion is filled with a first inorganic material that has light transmittance and a higher refractive index than the substrate, and then covers the upper surface to transmit light. The manufacturing method of the micro lens array of any one of Claim 1 to 3 which laminates | stacks the 2nd inorganic material provided with property. At the interface between the plurality of lenses and the second inorganic layer, the plurality of lenses have a higher refractive index than the second inorganic layer;
The method of manufacturing a microlens array according to claim 1, wherein the plurality of lenses have a convex shape. At the interface between the plurality of lenses and the second inorganic layer, the plurality of lenses have a higher refractive index than the second inorganic layer;
The method of manufacturing a microlens array according to claim 1, wherein the plurality of lenses have a concave shape.

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