JP2002103336A - Method for manufacturing microstructure array - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a microstructure array high in controllability and capable of enhancing a yield by etching a plating layer by a suitable etching solution. SOLUTION: First mask layers 3 are formed on a substrate having a conductive layer 2, a plurality of aperture parts 4 are formed to the first mask layers 3 at an interval corresponding to desired microstructure array arrangement, and first plating layers 5 are formed through the aperture parts 4 by electroplating. Second mask layers 6 are formed on the first plating layers 5 of the desired microstructure array region and the first plating layers 5 of the regions where no second mask layers 6 are formed by chemical etching, and the second mask layers 6 are removed to manufacture the microstructure array. In this method, the etching solution comprising a mixed aqueous solution of aqueous hydrogen peroxide and hydrochloric acid is used in chemical etching.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for manufacturing a microstructure array such as a microlens array used in the field of optoelectronics and the like (in this specification, unless otherwise specified, a metal mold is used). The term "mold" is used in a sense including a mold and a mold master).

[0002]

2. Description of the Related Art A microlens array has a plurality of microscopic substantially hemispherical lenses each having a diameter of several μm to several hundreds of μm. It has come to be used for applications.

On the other hand, the development of surface emitting lasers and the like, in which the interval between light emitting elements can be narrowed and which can be easily arrayed, has been advanced, and the demand for microlenses having a large numerical aperture (NA) which can narrow the interval between lens arrays has been increasing.

[0004] Similarly, with the development of semiconductor process technology, the distance between the elements has been narrowed, and the size of the light receiving elements has been increasingly reduced as seen in CCDs and the like. As a result, here too, a microlens array with a small lens spacing and a large numerical aperture is required. In such a microlens, a microlens with a high light-collecting rate and high utilization efficiency of light incident on the lens surface is desired.

[0005] Further, there is a similar demand in optical parallel processing / calculation, optical interconnection and the like, which are expected fields of optical information processing in the future.

Further, electroluminescence (EL)
Research and development of self-luminous display devices such as the above are also being actively conducted, and high-definition and high-luminance displays have been proposed. In such a display, there is a demand for a low-cost, large-area microlens array in addition to a small and large numerical aperture microlens array.

Further, in a microlens array mounted on a liquid crystal projector or the like, a drive substrate is provided to eliminate a decrease in the light collection rate due to a shift between the microlens and the pixel portion and to obtain a brighter image. It is necessary to provide an alignment marker for realizing high-accuracy alignment with the above.

[0008]

Under the circumstances described above, the ion exchange method (M. Oikawa, et al., Jpn. J.
Appl. Phys. 20 (1) L51-54, 1981), a method of manufacturing a microlens array in which a plurality of portions on a substrate made of multi-component glass are made to have a high refractive index to form a plurality of lenses. It has been known. However, in this method, the aperture diameter of the lens cannot be made larger than the distance between the lenses, and it is difficult to design a lens having a large numerical aperture.
Further, in order to produce a large-area microlens array, a large-scale production device such as an ion diffusion device is required, and there is a problem that production is not easy. Also, compared to molding using a mold, it is necessary to perform an ion exchange step for each glass, and if the manufacturing condition management of the manufacturing apparatus is not sufficiently performed, the quality of the lens, for example, variation in the focal length is large between lots. There was a problem of becoming. Also, this method is more expensive than the method using a mold.

Furthermore, in the ion exchange method, alkali ions for ion exchange are required in a glass substrate, and the material of the substrate is limited to alkali glass and is compatible with a semiconductor-based device on the premise that alkali ions are free. Is bad. Furthermore, since the thermal expansion coefficient of the glass substrate itself is significantly different from the thermal expansion coefficients of the light receiving device and the light emitting device substrate,
As the integration density of the devices increases, misalignment occurs due to mismatch of thermal expansion coefficients. In addition, it is known that the ion exchange method on the glass surface originally leaves a compressive strain on the surface, which inevitably causes a problem of a trade-off between residual stress and warpage of the glass surface, and the microlens array becomes large. Accordingly, it becomes difficult to bond and join the light receiving device and the light emitting device to the substrate.

As another method, a registry flow method (D. Daly, et al., Proc. Microlens Arrays Teddingto
n., p23-34, 1991). In this method, a resin formed on a substrate is patterned into a cylindrical shape using a photolithography process, and heated and reflowed to produce a microlens array. By this method, lenses of various shapes can be manufactured at low cost. Also, there are no problems such as thermal expansion coefficient and warpage as compared with the ion exchange method. However, in this method, the shape of the microlens strongly depends on the thickness of the resin, the wettability between the substrate and the resin, and the heating temperature. Variation is likely to occur.

Another method is to prepare a master of a microlens array, apply a lens material to the master, and peel off the applied lens material. In preparing a mold serving as an original plate, a method of drawing using an electron beam (JP-A-1-261601) and a method of etching and forming a part of a metal plate (JP-A-5-303909)
Publication). According to these methods, the microlens can be duplicated by molding, the variation does not easily occur between lots, and it can be manufactured at low cost. Further, as compared with the ion exchange method, problems such as occurrence of an alignment error and warpage due to a difference in thermal expansion coefficient can be avoided. However, in the method using an electron beam, an electron beam lithography apparatus is expensive and requires a large amount of capital investment, and the drawing area is limited.
There is a problem that it is difficult to produce an original plate having a large area over a corner.

Still another method is to form a mask layer having one-dimensionally or two-dimensionally arranged opening patterns on a base material and to perform etching from the openings (Japanese Patent Application Laid-Open No. HEI 0-1990).
8-136704). However, in this method, since etching is performed from the opening of the resist,
The bottom of the dug portion becomes flat and it is difficult to condense the light to a diameter equal to or less than the diameter of the opening. Further, in the etching method, since isotropic etching mainly using a chemical reaction is used, there is a problem that even a slight change in the composition or crystal structure of the base material makes it impossible to etch into a desired shape.

As a method of solving the above problems, a method of fabricating a hemispherical structure array by electroplating, fabricating a mold for a microlens using this as an original plate, and fabricating a microlens array from the mold. (JP-B-64-10169). According to this method, an inexpensive microlens mold that can be easily formed in a large format, has a simple manufacturing process, has high controllability, and is inexpensive can be manufactured. Further, a microlens having a small radius of curvature can be manufactured by a method using electroplating.

As a method of forming an alignment marker, there has been proposed a method of forming a pattern for a lens and a pattern for an alignment marker in the same process when forming a resist pattern (Japanese Patent Application Laid-Open No. 09-189901).

However, this method is disclosed in Japanese Patent Publication No. 64-1016.
Applying the method of JP-A No. 9 and forming a pattern for a lens and a pattern for an alignment marker in the same process when forming a resist pattern, and then performing electroplating, a current density distribution occurs due to the pattern shape for the alignment marker. However, the electric field is concentrated at the peripheral portion of the lens array pattern to promote plating growth, and an in-plane distribution occurs in the size of the hemisphere. Furthermore, a current density distribution occurs around the alignment marker pattern, and a distribution occurs in the size of the plating layer that grows in a desired microlens array region.

The present invention has been made in view of the above-mentioned problems of the prior art, and has the following objects: (1) the fabrication process is easy and the controllability is high, and (2) it is suitable for etching a plating layer. By using a simple etching solution, the yield can be increased, (3) the in-plane distribution of the microstructure array can be reduced, (4) the radius of curvature of the microstructure can be reduced, and (5) highly accurate alignment can be achieved. An object of the present invention is to provide a method for manufacturing a mold for a microstructure array such as a microlens array, which can include an alignment marker for performing the method.

[0017]

According to the present invention, there is provided a method of manufacturing a microstructure array such as a mold for a microlens array, which achieves the above object, using a substrate having a conductive portion, and Forming an insulating first mask layer on the active portion, and (2) forming a plurality of microstructure openings in the first mask layer at intervals corresponding to a desired microstructure array arrangement. (3) forming a first plating layer on the opening and the first mask layer through the opening by electroplating using the conductive portion as a cathode; and (4) the substrate and the first plating. Forming a second mask layer on the first plating layer in the desired microstructure array region of the layer; (5) chemically forming the first plating layer in the region where the second mask layer is not formed. Removing by etching, 6) A method for manufacturing a microstructure array having a step of removing a second mask layer, wherein the chemical etching in the step (5) uses an etching solution composed of a mixed aqueous solution of hydrogen peroxide and hydrochloric acid. Features. By using the etching solution composed of the mixed aqueous solution of the hydrogen peroxide solution and the hydrochloric acid, the etching failure was eliminated, and the yield was improved.

Based on the above basic configuration, the following:
More specific embodiments are possible. Further, (7) a step of removing the first mask layer after the step (3) may be performed. If possible, a second mask layer may be formed on the structure obtained in the step (3) as it is (the first mask layer may have a good adhesion to the conductive portion).
This is possible in the case of SG or the like. The plurality of first plating layers may be separated or may be formed until they are continuous.) The second plating layer may be formed by removing the first mask layer.
May be formed.

Further, (8) a step of forming a second plating layer or an electrodeposition layer from the first plating layer to the conductive portion or the first mask layer may be performed. As a result, the in-plane distribution of the microstructure array can be further reduced, and the first plating layer is firmly fixed to the conductive portion or the first mask layer, so that the structure is further strengthened. Examples of the electrodeposition liquid include an electrodeposition liquid of an electrodepositable organic compound (an acrylic acid resin of anionic electrodeposition, an epoxy resin of a cationic electrodeposition, etc.).

In the step (4), a second mask layer may be formed on the first plating layer in the alignment marker area outside the micro structure array area. Thereby, the structure for the alignment marker can be formed from the first plating layer at an appropriate position, and a microlens array or the like including the alignment marker can be manufactured with high yield.

The etching solution in the step (5) is as follows:
Preferably, it contains hydrogen peroxide, hydrochloric acid and water, and the liquid composition is 10 to 15% of hydrogen peroxide solution and 10 to 25% of hydrochloric acid.

The electroplating in the step (3) is preferably performed by copper electroplating or nickel electroplating. Preferably, a platinum electrode layer is used as the conductive portion.

In the step (2), the openings are circular or arranged at equal intervals in the left, right, up and down directions. These may be determined appropriately according to the application. Round,
A microstructure array having a substantially hemispherical shape or a semicylindrical shape (which can be formed into a hemispherical microlens array or a mold for a lenticular lens) can be formed by the microstructure opening such as a slit shape.

In the step (8), the second plating layer may be formed by electroless plating or the like. The microstructure array is typically manufactured as a microstructure array mold or a microlens array mold.

The above is the basic and more specific components of the present invention, and the details and operation thereof will be further described below along with typical examples.

First, the principle of forming a microstructure such as a hemisphere will be described. Typically, when electroplating is performed on a small or fine opening of an insulating layer formed on a substrate having a platinum electrode layer, a plating layer is first deposited in the opening,
When electroplating is further performed, a first layer is formed on the opening and the mask layer.
Plating layer begins to grow. If the size (diameter or width) of the opening is sufficiently smaller than the electroplating anode, the first plating layer grows isotropically with respect to the center of the diameter or width,
A first plating layer such as a hemisphere is formed on the opening and the mask layer. By making the shape of the opening circular, the first plating layer can be grown on the mask layer isotropically with respect to the center of the diameter. Compared to the method of forming an original plate by etching, when the current flowing between the anode and the cathode is stopped at the time when the desired shape is obtained, the deposition of plating can be stopped, so that etching is performed in the time until water washing. Such unexpected shape errors can be avoided, and the controllability of manufacturing is good.

Next, a typical example of a method for manufacturing a mold for a microstructure array, which is typically a microlens array, will be described. Here, a microlens or a microlens array refers to a microstructure as a representative. Of course, what is described here can also be applied to other methods of manufacturing a mold for a microstructure array. First, a first mask layer is formed over a substrate having an electrode layer.

Here, the platinum electrode layer exposed to the plating solution or the etching solution is a material which is not corroded by the plating solution or the etching solution to be used and does not alloy with the first plating layer made of nickel or copper. Particularly preferred as a layer.
The reason is that the first plating layer made of nickel or copper formed on the electrode layer is removed by etching, so if the first plating layer made of nickel or copper and the alloy layer are formed, the etching is removed. It may not be possible. As a material for the plating substrate, any material of a metal, a semiconductor, and an insulator may be used, and a metal plate, a glass substrate, a silicon wafer, or the like having good flatness can be used.

The first mask layer may be any material having an insulating property, and either an inorganic insulator or an organic insulator can be used. As a method for forming the electrode layer and the first mask layer, a thin film forming method such as a vacuum evaporation method, a spin coating method, a dipping method, and a chemical deposition method (CVD) is used.

Next, a plurality of microlens openings are formed in the first mask layer at a pitch corresponding to the pitch of the microlens array in a region wider than a desired microlens array region (ie, a use region). . The shape of the opening is desirably circular. In forming the opening, the opening is formed by a semiconductor photolithography process capable of forming a minute or fine opening and etching. When a photoresist is used as the first mask layer, an etching step can be omitted (that is, exposure and development are sufficient).

Next, electroplating is performed by the following method. Using the plating substrate as a work, immerse the substrate in a plating solution containing metal ions (particularly nickel or copper), connect an external power supply between the plating substrate and the anode plate, apply an electric current, and pass the first electric current through the opening.
Is formed. Plating is formed in the opening, and by continuing plating, the first plating layer also spreads on the first mask layer, and a structure such as a hemisphere is formed. The diameter of a lens formed by the microlens array mold to be manufactured is in the range of several μm to several hundred μm. Therefore, the size of the opening needs to be smaller than the desired diameter of the microlens. In order for plating to grow isotropically, the size of the opening should be smaller than the diameter or width of the structure such as a hemisphere. And the radius of curvature can be reduced.

The micro structure is formed by depositing metal ions in a plating bath by an electrochemical reaction.
In electroplating, the size of the first plating layer can be easily controlled by controlling the plating time and the plating temperature. The first plating layer formed here grows larger at the periphery of the array than at the center. This is because the current distribution is not uniform and the current concentrates at the ends of the electrodes.
Therefore, by forming the microlens opening group region wider than the desired microlens array region (that is, the use region), the region of the first plating layer which grows excessively larger than that of the central portion is desired. Out of the micro lens array area.

Subsequently, the first plating layer at the periphery of the array, which has grown excessively larger than the central portion, is selectively removed by a method as described below, so that the first plating layer having a substantially uniform height is removed. Can be obtained.

In the typical method, first, the first mask layer is removed. Next, the first, which grew to almost uniform size,
A second mask layer is formed on the desired microlens array region including the plating layer and the first plating layer region at an appropriate position outside the desired microlens array region. As a result, the first plating layer covered with the second mask layer exists in the first plating layer region at an appropriate position outside the microlens array region, and this is removed by etching in a later step. Can function as an alignment marker structure.

As the second mask layer, any of an inorganic material and an organic material can be used, but a material having resistance to an etching solution in a later step is used. As a method for forming the second mask layer, a thin film formation method such as a vacuum evaporation method, a spin coating method, and a dipping method is used. In forming the second mask layer only in the selected region, a semiconductor photolithography process and etching are used. Here, if a photoresist is used as the second mask layer, the etching step can be omitted.

Although it is not necessary to remove the first mask layer before forming the second mask layer, the removal of the first mask layer improves the adhesion of the second mask layer to the substrate. In particular, when both the first mask layer and the second mask layer are made of photoresist, the effect of improving the adhesion is great.

Next, the first plating layer exposed from the second mask layer is removed by etching. Here, the etching solution of the present invention will be described in detail below in comparison with other methods. Dry etching and wet etching are used as the etching method. In the case of dry etching, particularly for nickel, a reactive ion etching method or a plasma etching method has not been found, and etching is performed by a physical ion trimming method. It is difficult to remove only the first plating layer. As an etchant for wet etching, nitric acid is known, but there is a possibility that passivation occurs during the etching and the etching is stopped on the way. If the etching stops halfway, the first plating layer other than the first plating layer that should originally function as the alignment marker structure also remains. As a result, the position of the alignment marker cannot be determined, and a defective product that cannot be accurately aligned with a pixel of a driving substrate such as a liquid crystal projector is produced, thereby lowering the yield. Also, nitric acid,
Although a mixed solution of acetic acid and acetone is known as an etching solution, a novolak-based positive resist cannot be used for the second mask layer.

The etching solution of the present invention contains hydrogen peroxide, hydrochloric acid and water, and preferably uses an etching solution having a composition of 10 to 15% of hydrogen peroxide solution and 10 to 25% of hydrochloric acid solution. In addition, this etching liquid does not cause passivation during the etching and stop the etching during the etching. Further, with this etching solution, a novolak-based positive resist can be used for the second mask layer, and the first plating layer not covered with the second mask layer can be completely removed by etching.

Here, the electrode material is a metal having resistance to the above-mentioned etching solution, preferably platinum. Since platinum is used as the electrode material, there is no alloying with the first plating layer or corrosion by the above-mentioned etching solution, so that the etching is performed by the first plating made of nickel or copper exposed from the second mask layer. Stop when the layer is completely removed and a flat surface of the platinum electrode is obtained.

After the etching, the first plating layer in the microlens array region covered by the remaining second mask layer has a substantially uniform size and a hemispherical shape having a small in-plane distribution of diameter or width. Is a structure array. Also, the first plating layer as the structure for the alignment marker can be left because it is covered with the second mask layer.

Further, a plurality of microlens openings corresponding to a desired microlens pitch and openings where the first plating layer left unetched as an alignment marker structure is grown from the electrode layer are formed in the same process. As a result, relative displacement between the microlens array region and the alignment marker does not occur.

Further, in this method, a plurality of second
To provide a microlens array mold having a plurality of or a plurality of types of alignment marker structures and a small in-plane distribution of the size of the first plating layer from a single substrate. Is also possible. this is,
After the formation of the first plating layer, a region having a small in-plane distribution of the size of the first plating layer excluding a peripheral portion of the array pattern and a region of the first plating layer as an alignment marker structure are selectively formed. This is because the second mask layer can be formed first.

Next, the second mask layer is removed, and a second plating layer or an electrodeposition layer is formed from the first plating layer to the electrode layer (represented here by a plating layer). The method of forming the second plating layer may be either electroplating or electroless plating. However, by using electroless plating, a mold for a microlens array having high gloss can be obtained. Furthermore, since this is an isotropic plating growth, the radius of curvature in the diagonal direction and the horizontal direction of each plating layer in the microlens array region can be made equal, and the height of the plating layer in the microlens array region can be reduced. The height of the plating layer of the alignment marker structure can be made substantially equal.

As a result, the first plating layer is firmly fixed on the electrode layer, and it is possible to prevent the first plating layer from falling off in the subsequent steps, thereby improving the durability of the microlens array mold. .

The height of the plating layer in the microlens array region obtained as described above is almost equal to the height of the plating layer of the alignment marker structure. Therefore, the height of the lens vertex of the microlens array obtained from this becomes substantially equal to the height of the vertex of the alignment marker.
As a result, when bonding with a driving substrate or the like, the lens vertex of the microlens array and the vertex of the alignment marker are substantially in the same plane, and both are within the focal depth of the aligner-side lens system. Positioning can be realized.

The microlens array mold is obtained by forming a mold material on the microlens array mold master (original plate) and then peeling the mold (depending on the material of each part, the above structure may be obtained). Can be used as it is as a microstructure array such as a microlens array). Since the microlens array mold can be formed directly from the original plate formed by electroplating, it can be manufactured at low cost without requiring expensive equipment. As the method of peeling, the original plate and the substrate may be mechanically peeled. However, if the substrate is enlarged, the substrate, the mask layer, the first plating layer, and the like may be sequentially etched and removed from the rear surface because the substrate may be deformed at the time of peeling.

When the mold is formed after providing the sacrificial layer on the substrate and the plating layer, the mold and the substrate can be separated by removing the sacrificial layer. In this case, a material for the sacrificial layer is selected so that the mold is not corroded by an etchant for etching the sacrificial layer. When the plating layer and the substrate are not corroded by the etchant for etching the sacrificial layer, the substrate on which the plating layer is formed can be used a plurality of times as an original. If the original cannot be used due to scratches, dirt, etc. due to multiple uses, a mold master may be manufactured in the same manner.

As the material for the microlens mold, any material such as resin, metal, and insulator can be used as long as it can be formed on the substrate on which the plating layer is formed and can be peeled off. As a simple method of forming a mold, a solution in which a resin or a metal or glass is melted or dissolved is applied on a substrate on which a plating layer is formed, and after this is cured, it is peeled off by the peeling method described above. . In this case, as the mold material, a material that does not alloy the substrate or the plating layer is selected. As another method, a metal mold is formed by electroplating on a plating layer and an electrode layer using a substrate as a cathode. If a sacrifice layer is used, a mold electrode layer is formed on the sacrifice layer, and electroplating is performed using the mold electrode layer as a cathode.

Further, a microlens array can be formed by forming a material for forming a microlens on the microlens array mold and peeling it off. This makes it possible to easily manufacture microlenses having the same shape at low cost.
As a material of the microlens, a material that is easily peelable from a microlens mold is used. When a resin is used as the microlens material, a light-transmissive thermosetting resin, an ultraviolet-curing resin, an electron beam-curing resin, or the like is applied on a microlens array mold, and then cured by ultraviolet light irradiation, electron beam irradiation, or the like. Let it. During curing, no bubbles are formed. When applying a resin, degassing is preferably performed.

After curing, the resin is separated from the mold to form a microlens array. As a resin to be a microlens array, a material that can transmit light in a wavelength region of light used by a light receiving or light emitting device using a microlens is used. When a microlens is manufactured by the above method, alkali glass is not indispensable, and the limitations on the materials of the microlens and the supporting substrate can be reduced as compared with the ion exchange method. If molten glass is used instead of resin, a glass microlens array can be produced.

Of course, the mold of the present invention is not limited to a microlens array as long as it can be applied, and can be used for manufacturing any structure.

[0052]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

(First Embodiment) A first embodiment will be described with reference to manufacturing process diagrams shown in FIGS. In this embodiment, a 4-inch silicon wafer having a silicon dioxide film having a thickness of 1 μm formed on both sides by thermal oxidation using an oxidizing gas is used as the substrate 1 shown in FIG. On this wafer, the thin film forming method 1
Ti and Pt are each 50
{, 500} A film is formed continuously to form the electrode layer 2. A positive photoresist (Az1500: manufactured by Client Co.) is applied thereon to form a first mask layer 3.

Next, the photoresist is exposed and developed by photolithography to expose the electrode layer 2 according to a predetermined pattern, thereby forming an opening 4. Each opening 4 has a circular shape, and has a diameter of 95 mmφ in the plane of the silicon wafer.
Are provided in an array (in this embodiment, at equal intervals in the left, right, up, and down directions). Its diameter is 5 μm, and the distance between adjacent openings 4 is 18 μm (see FIGS. 1A and 2).

Subsequently, using the substrate 1 as a workpiece, the electrode layer 2 as a cathode, and a Ni plating bath composed of nickel sulfate, nickel chloride, boric acid and a brightener, a bath temperature of 50 ° C. and a cathode current without stirring. Ni plating is performed at a density of 40 A / dm ² . The first plating layer 5 made of Ni is first deposited and grown from the opening 4, and the first plating layer 5 also spreads on the first mask layer 3. Thus, the first plated layer 5 is grown until the radius of the first plated layer 5 at the center of the array becomes a hemispherical structure with a radius of about 10 μm (FIG. 1B).
Is a sectional view, and FIG. 3 is a top view). First in the center of the array
When the radius of the plating layer 5 is about 10 μm, the first plating layer 5 having a maximum radius of about 15 μm is formed around the array.
Was formed.

Next, the first mask layer 3 is removed with acetone and N, N-dimethylformamide. Then, a positive photoresist (AzP4620: manufactured by Client) is applied, exposed, and developed, and 1064 ×
A second mask layer 6 is selectively provided on the first plating layer 5 grown at a position corresponding to the 808 regions and the alignment marker. As a result, the first plating layer 5 around the array is exposed (FIG. 1C is a sectional view, and FIG. 4 is a top view). Here, since an alignment marker opening having a different shape is not particularly provided, the current density distribution is hardly affected by the opening 4 located at a position corresponding to the alignment marker.

Subsequently, using an etching solution containing hydrogen peroxide, hydrochloric acid, and water and having a liquid composition of 10% hydrogen peroxide solution and 25% hydrochloric acid, the first mask made of nickel exposed from the second mask layer 6 is used. The plating layer 5 is removed by etching (FIG. 1
(D) is a sectional view, and FIG. 5 is a top view). As a result, the first plating layer 5 made of nickel exposed from the second mask layer 6 could be completely removed. Here, the electrode layer 2
As a result, the electrode layer 2 was not corroded. The etching was stopped when the first plating layer 5 made of Ni existing in a region not covered by the second mask layer 6 was consumed.

Next, by removing the second mask layer 6 with acetone and N, N-dimethylformamide, 106
An array of 4 × 808 first plating layers 5 and alignment marker structures 8 can be formed (FIG. 1).
(E) is a sectional view, and FIG. 6 is a top view). At this time, the in-plane distribution of the radius of the first plating layer 5 was within 5%.

Next, Ni electroless plating was performed at a bath temperature of 90 ° C. using an electroless Ni plating solution (Alnic CT, manufactured by Pax) containing a hypophosphite reducing agent to form a second plating layer. 7 (FIG. 1D is a sectional view, and FIG. 7 is a top view). As a result, the first plating layer 5 is firmly fixed on the electrode layer 2, and the mold for the microlens array having a higher gloss can be obtained by using electroless plating for forming the second plating layer. . The radius of curvature of each plating layer in the diagonal direction and the horizontal direction is substantially equal, and the average radius of curvature is 20.
μm, and the distribution of the radius of curvature falls within ± 1 μm or less,
A mold having a uniform shape could be formed. Further, the in-plane distribution of the height of the plating layer in the region of the microlens group and the plating layer corresponding to the alignment marker structure 8 is also 5%.
Was within.

As described above, according to the present embodiment, the in-plane distribution of the size of each lens can be easily reduced, and an alignment marker which realizes high-precision alignment with an alignment marker on a driving substrate side of a liquid crystal device or the like. Thus, a method for manufacturing a mold for a microlens array having the above-described method can be realized.

Next, a typical example of a method for manufacturing a mold for a microlens array using the above structure as a mold master will be described.

A mold release agent for electroforming is applied on the mold master. Using this substrate as a cathode, a nickel plating bath composed of nickel sulfamate, nickel bromide, boric acid, and a brightener, a bath temperature of 50 ° C., a cathode current density of 5 A / dm ² , and N
i A metal mold is formed by electroplating. Thereafter, the mold is released from the substrate to form a microlens array mold.

An example of a method for manufacturing a convex microlens array using this mold will be described. After applying an ultraviolet curable resin to the microlens array mold, a glass substrate serving as a support substrate is mounted thereon. The resin is cured by ultraviolet irradiation and then peeled off to produce a convex microlens array. The convex microlens array was provided with an alignment marker for realizing highly accurate alignment, and the in-plane distribution of the lens diameter was within 5%.

Subsequently, the markers of the convex microlens array are aligned and adhered to the markers formed on the TFT (thin film transistor) liquid crystal substrate, so that each microlens is accurately arranged at a position corresponding to each pixel. Was completed. When these were connected to a drive circuit and driven as a liquid crystal projector, the incident light was condensed by the microlenses and a bright display image could be obtained.

(Second Embodiment) In the second embodiment, as in the first embodiment, thermal oxidation was performed using an oxidizing gas, and both surfaces were 1 μm thick.
A 4-inch φ silicon wafer on which a thick silicon dioxide film is formed is used as the substrate 1 shown in FIG. On this wafer, Ti and Pt were continuously formed at 50 ° and 500 °, respectively, by a vacuum sputtering method, which is one of the thin film forming methods.
To form A positive photoresist (Az15
00: manufactured by the client company) and the first mask layer 3
To form Next, the photoresist is exposed and developed by photolithography to expose the electrode layer 2, and the opening 4 is formed. The openings 4 have a circular shape and are provided in an array in a region of 95 mmφ on the surface of the silicon wafer. Its diameter is 5 μm, and the distance between adjacent openings 4 is 1 μm.
8 μm.

Subsequently, using the substrate 1 as a work, the electrode layer 2 as a cathode, a Cu plating bath comprising copper sulfate, sulfuric acid, hydrochloric acid and a brightener, a bath temperature of 40 ° C. and a cathode current density of 4 A / dm ² To perform Cu electroplating. First plating layer 5 made of Cu is first deposited and grown from opening 4, and first plating layer 5 spreads over first mask layer 3. Then, the first plating layer 5 is grown until the radius of the first plating layer 5 at the center of the array becomes a hemispherical structure of about 10 μm. When the radius of the first plating layer 5 was about 10 μm at the center of the array, the first plating layer 5 having a maximum radius of about 15 μm was formed at the periphery of the array.

Next, the first mask layer 3 is removed with acetone and N, N-dimethylformamide. Then, a positive photoresist (AzP4620: manufactured by Client) is applied, exposed, and developed, and 1064 ×
A second mask layer 6 is selectively provided on the first plating layer 5 grown at a position corresponding to 808 regions and alignment markers. As a result, the first plating layer 5 around the array was exposed. Next, a first plating layer made of copper exposed from the second mask layer 6 using an etching solution containing hydrogen peroxide, hydrochloric acid and water and having a liquid composition of 10% hydrogen peroxide and 25% hydrochloric acid. 5 is removed by etching. Here, the electrode layer was not corroded by using Pt as the electrode layer 2. Thereby, the second mask layer 6
The first plating layer 5 made of copper exposed from was completely removed. The etching was stopped when the first plating layer 5 made of copper present in a region not covered by the second mask layer 6 was consumed.

Next, by removing the second mask layer 6 with acetone and N, N-dimethylformamide, 106
An array of 4 × 808 first plating layers 5 and alignment marker structures 8 can be formed. At this time, the in-plane distribution of the radius of the first plating layer 5 was within 5%.

Next, Ni electroless plating was performed at a bath temperature of 90 ° C. using an electroless Ni plating solution (Alnic CT, manufactured by Pax) containing a reducing agent for hypophosphite to form a second plating layer. 7 is formed. Thereby, the first plating layer 5
Was firmly fixed on the electrode layer 2, and the electroless plating was used to form the second plating layer, whereby a mold for a microlens array having high gloss was obtained. The radius of curvature of each plating layer in the diagonal direction and the horizontal direction is almost equal, the average radius of curvature is 20 μm, and the distribution of the radius of curvature falls within ± 1 μm, and a mold having a uniform shape can be formed. Was. Further, the in-plane distribution of the height of the plating layer in the region of the microlens group and the plating layer corresponding to the structure for the alignment marker was within 5%.

As described above, also in this embodiment, the in-plane distribution of the size of each lens can be easily reduced, and an alignment marker for realizing high-precision positioning with respect to the alignment marker on the driving substrate side is provided. A method for manufacturing a mold for a microlens array was realized.

As described in the first embodiment, a mold for a microlens array can be formed by using the above mold as a master, and further a convex microlens array can be manufactured. The convex microlens array was provided with an alignment marker for realizing highly accurate alignment, and the in-plane distribution of the lens diameter was within 5%.

(Third Embodiment) In the third embodiment, a 5-inch φ silicon wafer having a 1 μm thick silicon dioxide film formed on both surfaces by thermal oxidation using an oxidizing gas is used as a substrate. Ti and Pt were deposited on the wafer by vacuum sputtering, which is one of the thin film forming methods, at 50 ° and 500 °, respectively.
The electrode layer 2 is formed by continuously forming a film. A positive photoresist (Az1500: manufactured by Client Co.) is applied thereon to form a first mask layer 3. Next, the photoresist is exposed and developed by photolithography, and the electrode layer 2 is exposed to form an opening 4. The openings 4 have a circular shape and are provided in an array in a region of 120 mmφ on the surface of the silicon wafer. Its diameter is 5 μm,
The distance between adjacent openings is 18 μm.

Using this substrate 1 as a work, the electrode layer 2
Using a nickel plating bath composed of nickel sulfate, nickel chloride, boric acid and a brightener, with the
Ni plating is performed at 50 ° C. and a cathode current density of 40 A / dm ² . The first plating layer 5 made of Ni is
And the first plating layer 5 spreads on the first mask layer 3 as well. Thus, the radius of the center of the array is about 1
The first plating layer 5 is grown until a hemispherical structure of 0 μm is formed. When the radius of the hemispherical structure was about 10 μm at the center of the array, a hemispherical structure having a maximum radius of about 15 μm was formed at the periphery of the array.

Next, the first mask layer 3 is removed with acetone and N, N-dimethylformamide. Then, a positive photoresist (AzP4620: manufactured by Client Co.) is applied, exposed and developed, and one of eight locations excluding the periphery of the array is removed.
On the first plating layer 5 grown at the position corresponding to the 064 × 808 regions and the eight sets of alignment markers (as shown in the first and second embodiments) respectively corresponding to the regions, Is provided with a second mask layer 6. Here, the current density distribution is hardly affected by the openings 4 provided for the alignment markers, and the first plating layer in the area covered with the second mask layer 6 in eight 1064 × 808 areas is provided. The in-plane distribution of the diameter of 5 was within 5%.

Subsequently, an etching solution containing hydrogen peroxide, hydrochloric acid and water and having a liquid composition of 15% of hydrogen peroxide solution and 10% of hydrochloric acid is used, and the first mask made of nickel exposed from the second mask layer 6 is used. The plating layer 5 is removed by etching. As a result, the first plating layer 5 made of nickel exposed from the second mask layer 6 could be completely removed. Here, the electrode layer 2 was not corroded by using Pt as the electrode layer 2. The etching was stopped when the first plating layer 5 made of Ni existing in a region not covered by the second mask layer 6 was consumed.

Next, by removing the second mask layer 7 with acetone and N, N-dimethylformamide, an array of 1064 × 808 first plating layers 5 at eight locations is obtained.
Eight sets of alignment marker structures could be formed. At this time, the in-plane distribution of the radius of the first plating layer 5 at each location was within 5%.

At this time, since each alignment marker structure 8 is a marker having an appropriate pattern and / or a combination thereof, they have different alignment marker structures.

Then, Ni electroless plating was performed at a bath temperature of 90 ° C. using an electroless Ni plating solution (Alnic CT, manufactured by Pax) containing a reducing agent for hypophosphite to form a second plating layer. 7 is formed. Thereby, the first plating layer 5
Was firmly fixed on the electrode layer 2, and the electroless plating was used to form the second plating layer, whereby a mold for a microlens array having high gloss was obtained. Further, the radius of curvature in the diagonal direction and the horizontal direction of each plating layer was almost the same, the average radius of curvature was 20 μm, the distribution of the radius of curvature was within ± 1 μm, and a mold having a uniform shape could be formed. . further,
The in-plane distribution of the heights of the plating layers corresponding to the structures for the alignment markers and the plating layers in the eight microlens group regions was within 5% (see FIG. 8).

As described above, according to the present embodiment, a single substrate
It is possible to realize a method capable of easily reducing the in-plane distribution of the size of each lens and manufacturing eight to eight types of molds for a microlens array equipped with an alignment marker for realizing highly accurate alignment. did it.

Next, the mold master manufactured by the above method is used.
-Apply a mold release agent for electroforming on top. And shade this board
Poles, nickel sulfamate and nickel bromide
Using Ni plating bath consisting of acid and brightener, bath temperature 50
° C, cathode current density 5A / dm ²Perform Ni electroplating with
To form a mold. Then, release the mold from the substrate
A mold for a microlens array is formed.

After applying the ultraviolet curing resin to the microlens array mold, a glass substrate serving as a support substrate is mounted thereon. The resin is cured by irradiation with ultraviolet light and then peeled off and cut off, whereby a convex microlens array having eight to eight types of alignment markers can be manufactured from one mold. Each myro lens array was provided with an alignment marker for realizing highly accurate alignment, and the in-plane distribution of lens diameter was within 5%.

[0082]

As described above, according to the present invention,
A microstructure array having an alignment marker that is easy to manufacture, has high controllability, has a small radius of curvature, and can realize a microstructure having a small in-plane distribution in the array, and can realize high-precision alignment. A method of manufacturing a mold for a microstructure array that can be manufactured was realized. At this time, the use of an etching solution containing hydrogen peroxide, hydrochloric acid and water eliminated etching defects and improved the yield.

Further, a plurality of types of molds for a micro-structure array such as a micro-lens array in which variation in the size of a micro-structure such as a lens was suppressed could be formed on one substrate surface. . Since the height of the apex of the microlens array obtained from these microlens array molds and the height of the apex of the alignment marker are in substantially the same plane and both come within the focal depth of the aligner-side lens system, Highly accurate alignment can be realized. Thereby, the overlay accuracy with the TFT substrate or the like is improved, the alignment between the pixel portion and the like and the microlens is improved, and the effect of improving the pixel aperture ratio and the light collection ratio of the microlens is achieved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a manufacturing process of a microlens array mold according to a first embodiment of the present invention.

FIG. 2 is a top view of the step (a) of FIG.

FIG. 3 is a top view of step (b) in FIG. 1;

FIG. 4 is a top view of the step (c) in FIG. 1;

FIG. 5 is a top view of step (d) in FIG. 1;

FIG. 6 is a top view of step (e) in FIG. 1;

FIG. 7 is a top view of step (f) in FIG. 1;

FIG. 8 is a top view showing a microlens array mold according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Electrode layer 3 1st mask layer 4 Opening 5 1st plating layer 6 2nd mask layer 7 2nd plating layer 8 Alignment marker

Claims (14)

[Claims] 1. A substrate having a conductive portion, (1) a step of forming an insulating first mask layer on the conductive portion, (2) a desired microstructure on the first mask layer Forming a plurality of microstructure openings at intervals corresponding to the array arrangement; (3) forming a plurality of microstructure openings on the openings and the first mask layer through the openings by electroplating using the conductive portions as cathodes; (4) forming a second mask layer on a first plating layer in a desired microstructure array region of the substrate and the first plating layer; A step of removing the first plating layer in a region where the second mask layer is not formed by chemical etching; and (6) a step of removing the second mask layer. , The chemical edge in step (5) A method for manufacturing a microstructure array, wherein the etching uses an etching solution comprising a mixed aqueous solution of hydrogen peroxide and hydrochloric acid. 2. The method according to claim 1, further comprising the step of: (7) removing the first mask layer after the step (3). 3. The method according to claim 1, further comprising the step of: (8) forming a second plating layer or an electrodeposition layer from the first plating layer to the conductive portion or the first mask layer.
Or the method for producing a microstructure array according to 2. 4. The method according to claim 1, wherein in the step (4), a second mask layer is formed also on the first plating layer in the alignment marker area outside the microstructure array area. Or the method for producing a microstructure array according to item 3. 5. The microstructure according to claim 4, wherein a structure for an alignment marker is formed from a first plating layer covered with a second mask layer in the alignment marker region in the step (4). Method for producing structure array. 6. The etching solution in the step (5) contains hydrogen peroxide, hydrochloric acid and water, and has a liquid composition of 10% hydrogen peroxide solution.
The method for producing a microstructure array according to any one of claims 1 to 5, wherein the concentration is 10 to 25% and the hydrochloric acid is 10 to 25%. 7. The method according to claim 1, wherein the electroplating in the step (3) is performed by electrolytic copper plating.
The method for producing a microstructure array according to any one of the above. 8. The method according to claim 1, wherein the electroplating in the step (3) is performed by electronickel plating.
7. The method for producing a microstructure array according to any one of items 1 to 6. 9. The method for manufacturing a microstructure array according to claim 1, wherein an electrode layer of platinum is used as said conductive portion. 10. The method according to claim 1, wherein in the step (2), the opening is circular. 11. The method of manufacturing a microstructure array according to claim 1, wherein, in the step (2), the openings are arranged at equal intervals vertically and horizontally. 12. The method according to claim 3, wherein in the step (8), the second plating layer is formed by electroless plating. 13. The microstructure array is a microstructure array mold.
The method for producing a microstructure array according to any one of the above. 14. The microstructure array mold is a microlens array mold.
3. The method for producing a microstructure array according to item 1.