JP3684147B2 - MICROSTRUCTURE ARRAY AND METHOD FOR MANUFACTURING THE SAME - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mold for producing a micro structure array such as a micro lens array used in the field of optoelectronics or the like (in this specification, a mold is referred to as a mold unless otherwise specified). And a micro structure array such as a microlens array, and the like.
[0002]
[Prior art]
A microlens array is composed of a plurality of small, substantially hemispherical lenses having a diameter of several μm to several hundreds of μm, and is used for various applications such as liquid crystal display devices, light receiving devices, and fiber-to-fiber connections in an optical communication system. It has become like this.
[0003]
On the other hand, the development of surface emitting lasers and the like that can narrow the interval between the light emitting elements and can be easily arrayed has progressed, and the demand for microlenses that can narrow the interval between lens arrays and have a large numerical aperture (NA) is increasing.
[0004]
Similarly, in the light receiving element, with the development of the semiconductor process technology, the element interval is narrowed, and the light receiving element is increasingly miniaturized as seen in a CCD or the like. As a result, here again, a microlens array having a small lens interval and a large numerical aperture is required. In such a microlens, there is a demand for a microlens having a high condensing rate with high utilization efficiency of light incident on the lens surface.
[0005]
Further, there are similar demands in the field of optical information processing, which is expected in the future, such as optical parallel processing / calculation and optical interconnection.
[0006]
In addition, research and development of self-luminous display devices such as electroluminescence (EL) have been extensively conducted, and high-definition and high-luminance displays have been proposed. In such a display, there is a demand for a low-cost and large-area microlens array in addition to a microlens array having a small size and a large numerical aperture.
[0007]
[Problems to be solved by the invention]
Under the circumstances described above, conventionally, ion exchange method (M. Oikawa, et al., Jpn. J. Appl. Phys. 20 (1) L51-54, 1981) is used on a substrate made of multicomponent glass. A method of manufacturing a microlens array in which a plurality of lenses are formed by increasing the refractive index at a plurality of locations is known. However, with this method, it is difficult to design a lens having a large numerical aperture because the aperture diameter of the lens cannot be made larger than the distance between the lenses.
[0008]
Moreover, in order to produce a large-area microlens array, a large-scale manufacturing apparatus such as an ion diffusion apparatus is required, and there is a problem that manufacturing is not easy. In addition, it is necessary to perform an ion exchange process for each glass compared to molding using a mold. If manufacturing conditions of manufacturing equipment are not sufficiently managed, variations in lens quality, such as focal length, will be large between lots. There was a problem of becoming. Moreover, this method becomes expensive compared with the method using a metal mold | die.
[0009]
Furthermore, in the ion exchange method, alkali ions for ion exchange are essential in the glass substrate, and the compatibility of the substrate material is limited to alkali glass and the semiconductor-based device is premised on alkali ion free. Furthermore, since the thermal expansion coefficient of the glass substrate itself is significantly different from the thermal expansion coefficient of the substrate of the light receiving device or the light emitting device, misalignment due to mismatch of the thermal expansion coefficients occurs as the integration density of the elements increases. Originally, the ion exchange method on the glass surface is known to leave a compressive strain on the surface, which inevitably causes a trade-off problem between residual stress on the glass surface and warpage deformation, and the microlens array becomes large. Accordingly, it becomes difficult to bond and join the light receiving device and the substrate of the light emitting device.
[0010]
As another method, there is a method in which an original plate of a microlens array is manufactured, a lens material is applied to the original plate, and the applied lens material is peeled off. In producing a mold as an original plate, there are a method of drawing using an electron beam (Japanese Patent Laid-Open No. 1-261601) and a method of forming a part of a metal plate by etching (Japanese Patent Laid-Open No. 5-303099). . In these methods, microlenses can be duplicated by molding, and variations among lots are unlikely to occur, and can be manufactured at low cost. In addition, problems such as alignment errors and warping due to a difference in thermal expansion coefficient can be avoided as compared with the ion exchange method. However, in the method using an electron beam, an electron beam drawing apparatus is expensive and requires a large amount of capital investment, and the drawing area is limited. There are problems such as difficulty.
[0011]
In addition, the etching method uses isotropic etching mainly utilizing a chemical reaction, so that there is a problem that if the composition or crystal structure of the metal plate changes even slightly, it cannot be etched into a desired shape. In the etching method, if the desired shape is obtained, the etching is continued unless it is immediately washed with water. In the case of forming a microlens, there is a case where the desired shape is deviated due to etching that proceeds from the time when the desired shape is obtained to the time of washing with water.
[0012]
Another method is the registry flow method (D. Daly, et al., Proc. Microlens Arrays Teddington., P23-34, 1991). In this method, a resin formed on a substrate is patterned into a cylindrical shape using a photolithography process, heated and reflowed to produce a microlens array. By this method, lenses having various shapes can be manufactured at low cost. In addition, there are no problems such as thermal expansion coefficient and warpage as compared with the ion exchange method.
[0013]
[Problems to be solved by the invention]
However, in this registry flow method, when adjacent lenses are brought into contact with each other by reflow, a desired lens shape cannot be maintained due to surface tension. That is, it is difficult to increase the light collection rate by touching adjacent lenses to reduce the light unused area between the lenses.
[0014]
The present invention has been made in view of the above-mentioned problems of the prior art, and its purpose is as follows.
(1) The height of microstructures such as lenses can be made relatively large and the curvature can be increased,
(2) It can be manufactured relatively inexpensively,
(3) Easily eliminate unused areas between microstructures such as adjacent lenses,
An object of the present invention is to provide a micro structure array which is a mold for a micro structure array such as a micro lens array, a manufacturing method thereof, and the like.
[0015]
[Means for Solving the Problems]
The microstructure array of the present invention that achieves the above object is provided with a plurality of cylindrical or spherical curved projections discretely arranged on a substrate according to the desired arrangement of the microstructure arrays, and on the curved projections. In addition, a micro structure array having a continuous film with a substantially uniform film thickness, wherein the contact angle between the curved protrusion and the substrate (the angle formed by the contact surface with the curved protrusion at the place where the curved protrusion and the substrate are in contact with the substrate surface) The angle on the curved projection side) is larger than 90 degrees , and adjacent curved projections are connected at the position of the maximum diameter of the curved surface by the continuous film . Since the contact angle is greater than 90 degrees, the height of the microstructure can be made relatively large and the curvature can be increased. In addition, since a continuous film is formed over the substrate and the curved projection, the in-plane distribution of the size of the micro structure array can be reduced, and the cylindrical or spherical projection is firmly fixed to the substrate, thereby further strengthening the structure. become.
[0016]
In the above basic configuration, the following more specific modes are possible.
When the radius of the curved projection is l, the contact angle between the curved projection and the substrate is θ, and the height h from the substrate at the center of the curved projection is h = −l cos θ, l and h are the thickness t of the continuous film. And the following formula d / 2 ≦ l + h with respect to the arrangement pitch d of the curved projections
h ≦ t, r ≧ d / 2
Thus, the unused area between the microstructures can be surely eliminated.
[0017]
The curved protrusions may be formed by, for example, patterning a thermoplastic material layer on a substrate in a desired shape according to the arrangement of the desired microstructure array, and deforming the patterned thermoplastic material layer by heat treatment in a discrete state. Can be formed.
[0018]
The continuous film may be a plating or electrodeposition layer such as an electroplating layer or an electroless plating layer, or may be formed by chemical deposition (CVD) or vacuum deposition. The continuous film is made of an inorganic material such as nickel or an organic material such as PSG.
[0019]
The curved protrusions may all be formed in the same shape, or may be regularly arranged such that they are arranged at equal intervals in the left and right and up and down directions, or may be irregularly arranged. What is necessary is just to determine these suitably according to a use.
[0020]
Curved protrusions for the alignment marker structure may be formed also in the alignment marker region outside the arrangement region for the microstructure array.
[0021]
The substrate, the curved protrusions and the continuous film are transparent, and the micro structure array can be used as it is as a micro lens array.
[0022]
The micro structure array is typically a micro structure array mold such as a micro lens array mold.
[0023]
Further, the manufacturing method of the microstructure array of the present invention that achieves the above object is as follows: (1) A plurality of cylindrical surfaces or spherical curved surfaces that are discretely arranged on the substrate according to the arrangement of the desired microstructure array. The protrusion has a contact angle between the curved protrusion and the substrate (the angle formed between the contact surface with the curved protrusion and the substrate surface where the curved protrusion and the substrate are in contact, and the angle on the curved protrusion side) is greater than 90 degrees. And (2) forming a continuous film having a substantially uniform film thickness so that adjacent curved projections are connected to each other at the position of the maximum diameter of the curved surface on the curved projection and the substrate. .
[0024]
Furthermore, the imaging device or display device of the present invention that achieves the above object is provided with each light receiving unit or each of the microlens array or the microlens array manufactured by using the manufacturing method described above at a position corresponding to each lens. Each pixel opening portion surrounded by a light shielding layer is provided.
[0025]
The above are the basic and more specific components of the present invention, the details and operation of which will be further described below along the typical example of FIG.
[0026]
A typical example of a method for producing a mold for a microstructure array, which is typically a microlens array, is shown. Here, the term “microlens” or “microlens array” refers to a microstructure. Of course, what is described here can also be applied to other methods for manufacturing a mold for a microstructure array.
[0027]
As the substrate material of the present invention, glass, quartz, ceramics, resin, metal, crystal material and the like can be used. Next, a spherical or cylindrical projection 3 (represented by a spherical projection here) is provided on the substrate 2. The contact angle between the spherical protrusion 3 and the substrate 2 is greater than 90 degrees.
[0028]
As a method for forming the spherical protrusions 3, a thermoplastic material layer is formed on a substrate, and the thermoplastic material layer is etched and patterned according to a desired lens pitch and number by, for example, semiconductor photolithography and etching. Here, if a photoresist is used for the thermoplastic material layer, the etching step can be omitted. At the same time, a pattern of an alignment marker structure can be formed. Further, if the patterning of the thermoplastic material layer is performed in a line shape, a mold for a lenticular lens can be formed. In addition, a method of dropping small droplets of thermoplastic material on a substrate according to a desired pattern may be used.
[0029]
By performing a reflow process at a temperature equal to or higher than the thermal deformation temperature on the patterned thermoplastic material layer, the thermoplastic material layer that is scattered is formed into a substantially spherical shape or a cylindrical surface shape due to its thermal deformability and surface tension. Transforms into Here, if the surface energy of the substrate (which is reduced by the water repellent treatment, the thermoplastic material is repelled more strongly) and the thickness of the thermoplastic material layer are controlled, the shape of the thermoplastic material can be freely adjusted. And the curvature can be controlled. In this state, a plane portion exists between the adjacent microstructures of the thermoplastic material.
[0030]
Next, the continuous film 4 is provided on them. The continuous film 4 is formed with a substantially uniform film thickness on the substrate surface and the spherical projection surface. Methods for forming such a continuous film include plating methods such as electroplating and electroless plating, chemical deposition methods (CVD methods), electrodeposition (the electrodeposition liquid contains an electrodepositable organic compound (anion type electrodeposition). An acrylic acid resin, a cationic electrodeposition epoxy resin, etc.), a vacuum deposition method, or the like. The continuous film 4 is formed on the spherical protrusion and the substrate until there is no plane portion between the spherical protrusions. As a result, there is no plane portion between adjacent spherical protrusions formed by patterning. If this is used as a mold for a microlens array, a microlens array with high light utilization efficiency can be obtained.
[0031]
When electroplating is used as a method for forming a continuous film plating layer, it is necessary to form an electrode layer on the spherical protrusion and the substrate, but this is not necessary when electroless plating is used. In plating, the curved surface shape can be easily controlled by controlling the plating time and the plating temperature. The main plating metals include Ni, Au, Pt, Cr, Cu, Ag, Zn, etc. for single metals, and Cu—Zn, Sn—Co, Ni—Fe, Zn—Ni, etc. for alloys. Any material that can be plated can be used.
[0032]
If it is desired to accurately maintain the curvature of the profile of the spherical protrusion, electroless plating, chemical deposition, or the like that allows more isotropic layer growth is preferable as the method for forming the continuous film. Again, the shape and curvature of the microstructure can be freely controlled by controlling the thickness of the continuous film.
[0033]
As shown in FIG. 1, when the radius of the spherical protrusion is l, the contact angle between the spherical protrusion 3 and the substrate 2 is θ, and the height h from the substrate 2 at the center of the spherical protrusion 3 is defined as follows: H = −l cos θ,
D / 2 ≦ l + h with respect to spherical projection pitch d
And when the thickness of the continuous film 4 is t, h ≦ t
And r = 1 + t ≧ d / 2 with respect to the radius of curvature r of the lens
If the control is performed so as to hold, a microlens array and a microlens array mold 1 having a large curvature can be obtained, and an unused area of light between adjacent lenses is surely eliminated.
[0034]
Since the contact angle θ between the spherical protrusion 3 and the substrate 2 is larger than 90 degrees, the point where the distance between adjacent spherical protrusions is the closest is the position of the maximum diameter of the spherical protrusion, and d / 2 ≦ l + h.
If the continuous film 4 is provided to such a thickness that the adjacent spherical surfaces 3 are connected to each other and there is no plane portion between the spherical surfaces, the adjacent spherical surfaces are connected at the position of the maximum diameter of the spherical protrusion 3. = L + t ≧ d / 2
become. Thus, the microlens array and the microlens array mold 1 having a large curvature are obtained.
[0035]
Here, the thickness t of the continuous film 4 is d / 2 = l + t.
If so, the relationship between the lens curvature radius r and the spherical protrusion pitch d is r = d / 2.
Thus, a microlens array and a microlens array mold having exactly a hemispherical shape are realized.
[0036]
The above condition is that if the thickness t of the continuous layer 4 is set to a size of about the height h of the spherical protrusion 3, the continuous layer 4 is connected at the place where the spherical protrusions 3 are closest to each other. This is a condition for the continuous layer 4 to be gradually connected to the upper part from the substrate 2 as the thickness t of 4 is increased.
[0037]
As described above, in the above manufacturing method, for example, after patterning a thermoplastic material layer in a desired shape according to the arrangement of a desired microstructure array using semiconductor photolithography, these are heated and the thermoplastic material layer is heated. The spherical protrusion 3 is formed by controlling the thermal deformability and surface tension of the substrate so that the contact angle θ between the spherical protrusion 3 and the substrate 2 is greater than 90 degrees, and isotropic growth is performed by electroless plating or CVD. The micro structure array can be manufactured by a simple method of forming the continuous film 4 by the film forming method. In this way, a microlens array and a microlens array mold 1 having a spherical microstructure array with a small in-plane distribution and a uniform size can be obtained.
[0038]
A concave microlens array mold can be obtained by forming a mold material on the microlens array mold master (original) and then peeling the mold (depending on the material of each part, the structure described above). Can also be used as a micro structure array such as a micro lens array). Since the microlens array mold can be formed directly from the above-mentioned original plate, it does not require expensive equipment and can be manufactured at low cost. As a peeling method, the original and the substrate may be mechanically peeled off. However, since it may be deformed at the time of peeling when it is enlarged, the substrate 2, the spherical protrusion 3, and the continuous film 4 may be sequentially removed from the back surface by etching.
[0039]
When the mold is formed after providing the sacrificial layer on the continuous film 4, 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 the etchant for etching the sacrificial layer. When the continuous film 4 and the substrate 2 are not corroded by the etchant for etching the sacrificial layer, the substrate on which the continuous film 4 is formed can be used a plurality of times as an original plate. If the original becomes unusable due to scratches, dirt, etc. due to multiple use, a mold master may be produced by the same method.
[0040]
As a material for the mold for the microlens, any material such as a resin, a metal, and an insulator can be used as long as it can be formed on the substrate 2 on which the continuous film 4 is formed and can be peeled off. As a simple mold forming method, a molten or dissolved solution of resin, metal, or glass is applied on the substrate 2 on which the continuous film 4 is formed, and after this is cured, it is peeled off by the peeling method described above. Form. In this case, a material that does not alloy the substrate or the continuous film is selected as the mold material. As another method, an electrode layer is formed on the continuous film 4 using the substrate as a cathode, and a mold is electroplated. If a sacrificial layer is used, a mold electrode layer is formed on the sacrificial layer, and electroplating is performed using the mold electrode layer as a cathode.
[0041]
Furthermore, a microlens array can be formed by forming a material to be a microlens on the microlens array mold and then peeling it off. Thereby, the relationship between the radius of curvature r and the spherical protrusion pitch d is r ≧ d / 2 at low cost and easily.
Thus, a microlens array having no light unused area can be produced.
[0042]
As the material of the microlens, a material that is easily peelable from the microlens mold is used. When resin is used as the microlens material, light transmissive thermosetting resin, UV curable resin, electron beam curable resin, etc. are applied on the mold for microlens array and then cured by UV light irradiation, electron beam irradiation, etc. Let During curing, no bubbles are formed. When applying the resin, it is preferable to deaerate.
[0043]
After curing, the resin is peeled from the mold to form a microlens array. As the resin for forming the microlens array, a material capable of transmitting light in the wavelength region of light used by the light receiving or light emitting device using the microlens is used. In the case of producing a microlens by the above method, alkali glass is not essential, and the restrictions on the materials of the microlens and the support 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.
[0044]
Of course, the mold of the present invention can be used for manufacturing any structure, not limited to the microlens array, if applicable.
[0045]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments and examples of the present invention will be described below in detail with reference to the drawings.
[0046]
(First Example)
FIGS. 2A and 2B are a top view and a cross-sectional view showing a first embodiment of the present invention.
[0047]
2 (a) and 2 (b), 1024 × 768 spherical protrusions 3 are formed at a pitch of 18 μm on a 2-inch φ silicon substrate 2 and isotropic from the silicon substrate 2 to the spherical protrusions 3. An electroless nickel plating layer grown as a continuous film 4 is formed.
[0048]
In this embodiment, the radius 1 of the spherical protrusion 3 is 8.5 μm, the height h of the spherical protrusion from the substrate 2 is 4.2 μm, and the contact angle θ between the spherical protrusion 3 and the substrate 2 is 120 degrees. Further, the spherical projection pitch d in the diagonal direction is 25.4 μm, and the thickness t of the continuous film 4 is 4.2 μm.
[0049]
Therefore, the relationship between the radius of curvature r (= l + t) of this microlens array mold and the spherical protrusion pitch d in the diagonal direction is r = d / 2 = 12.7 μm (= 1 + h).
And the surface of the continuous layer 4 has exactly a hemispherical shape.
[0050]
Next, a method for producing a microlens array mold using the above structure as a master will be described. A mold release agent for electroforming was coated thereon, this substrate was used as a cathode, a Ni plating bath composed of nickel sulfamate, nickel bromide, boric acid and a brightener was used. The bath temperature was 50 ° C., the cathode current density was 5 A / Ni electroplating is performed at dm ² to form an electroformed layer. Thereafter, the mold is released from the substrate to form a microlens array mold.
[0051]
Using this microlens array mold, the microlens array is manufactured as follows. After the ultraviolet curable resin is applied to the microlens array mold, a glass substrate serving as a support substrate is placed thereon. 1024 × 768 convex microlens arrays can be produced by peeling after curing the resin by ultraviolet irradiation. The convex microlens array obtained here has no unused area of light because there is no plane part between adjacent lens spherical surfaces. Also, in the microlens array obtained here, the relationship between the lens curvature radius r and the diagonal lens pitch d is r = d / 2 = 12.7 μm.
And had exactly a hemispherical shape.
[0052]
(Second embodiment)
FIGS. 2A and 2B are a top view and a cross-sectional view showing a second embodiment of the present invention.
[0053]
2A and 2B, 1024 × 768 spherical protrusions 3 are formed on a 2-inch φ silicon substrate 2 at a pitch of 18 μm, and isotropic from the silicon substrate 2 to the spherical protrusions 3. An electroless nickel plating layer grown as a continuous film 4 is formed.
[0054]
In this embodiment, the radius 1 of the spherical protrusion 3 is 6.8 μm, the height h of the spherical protrusion from the substrate 2 is 5.9 μm, and the contact angle θ between the spherical protrusion 3 and the substrate 2 is 150 degrees. The diagonal lens pitch d is 25.4 μm, and the thickness t of the continuous film 4 is 5.9 μm.
[0055]
Therefore, the relationship between the radius of curvature r (= l + t) of this microlens array mold and the spherical protrusion pitch d in the diagonal direction is r = d / 2 = 12.7 μm (= 1 + h).
And has exactly a hemispherical shape.
[0056]
Also in this embodiment, as in the first embodiment, a microlens array mold can be formed, and 1024 × 768 convex microlens arrays can be manufactured. The convex microlens array obtained here also has no unused area of light because there is no planar portion between adjacent lens spherical surfaces. Also, in the microlens array obtained here, the relationship between the lens curvature radius r and the diagonal lens pitch d is r = d / 2 = 12.7 μm.
Thus, the same microlens array as in the first example could be obtained.
[0057]
(Third embodiment)
FIG. 2C is a cross-sectional view showing a third embodiment of the present invention.
[0058]
In FIG. 2 (c), 1024 × 768 spherical protrusions 3 are formed at a pitch of 18 μm on a 2-inch φ silicon substrate 2 and grown isotropically from the silicon substrate 2 to the spherical protrusions 3. An electroless nickel plating layer is formed as the continuous film 4.
[0059]
In this embodiment, the radius 1 of the spherical protrusion 3 is 8.5 μm, the height h of the spherical protrusion from the substrate 2 is 4.2 μm, and the contact angle θ between the spherical protrusion 3 and the substrate 2 is 120 degrees. The diagonal lens pitch d is 25.4 μm, and the thickness t of the continuous film 4 is 5 μm.
[0060]
Accordingly, the radius of curvature r (= l + t) of the microlens array mold is r = 13.5 μm (> d / 2 = 1 / l = 12.7 μm).
It is. Compared to the first and second embodiments, here, the continuous layer 4 is connected slightly above the level of height l (see FIG. 2C), and the radius of curvature r is slightly larger. .
[0061]
Also in this embodiment, as in the first embodiment, a microlens array mold can be formed, and 1024 × 768 convex microlens arrays can be manufactured. The convex microlens array obtained here also has no unused area of light because there is no planar portion between adjacent lens spherical surfaces. The microlens array obtained here has a lens radius of curvature r = 13.5 μm.
Met.
[0062]
(Fourth embodiment)
Also in this embodiment, 1024 × 768 spherical protrusions 3 are formed on a 2-inch φ silicon substrate 2 at a pitch of 18 μm, and electroless nickel plating isotropically grown from the silicon substrate to the spherical protrusions. The layer is formed as a continuous film 4.
[0063]
The radius 1 of the spherical protrusion 3 is 8.5 μm, the height h from the center of the spherical protrusion from the substrate 2 is 4.2 μm, and the contact angle θ between the spherical protrusion 3 and the substrate 2 is 120 degrees. The diagonal lens pitch d is 25.4 μm, and the thickness t of the continuous film 4 is 4.2 μm.
[0064]
Therefore, the relationship between the radius of curvature r (= l + t) of this microlens array mold and the spherical protrusion pitch d in the diagonal direction is r = d / 2 = 12.7 μm (= l + h).
And has exactly a hemispherical shape. An alignment marker structure is formed in the same plane at a position different from these spherical surfaces.
[0065]
Also in this embodiment, as in the first embodiment, a microlens array mold can be formed, and 1024 × 768 convex microlens arrays can be manufactured. The convex microlens array obtained here also has no unused area of light because there is no plane part between adjacent lens spherical surfaces. In the microlens array obtained here, the relationship between the radius of curvature r and the lens pitch d in the diagonal direction is r = d / 2 = 12.7 μm.
And has exactly a hemispherical shape. Furthermore, the alignment marker 5 is formed in the same plane (FIG. 3). In FIG. 3, there are alignment markers 5 at the four corners.
[0066]
By using this, the microlens array 5 was aligned with the alignment marker formed on the TFT liquid crystal substrate, and each microlens could be placed at a position corresponding to each pixel. When these were connected to a drive circuit and driven as a liquid crystal projector, incident light was collected by a microlens and a bright display image could be obtained.
[0067]
(5th Example)
In this embodiment, 1024 × 768 spherical protrusions 3 are formed on a 5-inch φ silicon substrate 2 at a pitch of 18 μm, and electroless nickel isotropically grown from the silicon substrate to the spherical protrusions. The plating layer formed as the continuous film 4 is provided at eight places at intervals of 1.8 mm in the same plane. Further, as a marker structure used for alignment such as bonding, an alignment marker pattern 5 is formed at an arbitrary position other than the 1024 × 768 region (FIG. 4). In FIG. 4, alignment marker structures 5 are formed at the four corners of each 1024 × 768 region.
[0068]
In this embodiment, the radius 1 of the spherical protrusion 3 is 9.5 μm, the height h of the spherical protrusion from the substrate 2 is 3.2 μm, and the contact angle θ between the spherical protrusion 3 and the substrate 2 is 110 degrees. The diagonal lens pitch d is 25.4 μm, and the thickness t of the continuous film 4 is 3.2 μm.
[0069]
Therefore, the relationship between the radius of curvature r (= l + t) of this microlens array mold and the spherical protrusion pitch d in the diagonal direction is r = d / 2 = 12.7 μm (= l + h).
And has exactly a hemispherical shape.
[0070]
Also in this embodiment, as in the first embodiment, a microlens array mold can be formed, and a microlens array mold having eight alignment markers 5 and 1024 × 768 patterns in the same plane is obtained. It is done.
[0071]
Using this microlens array mold, an ultraviolet curable resin is applied thereto, and then a glass substrate serving as a support substrate is placed thereon. Eight convex microlens arrays could be fabricated from a single mold by peeling and cutting the resin after curing with ultraviolet irradiation. This microlens array also has no unused area of light because there is no plane portion between adjacent lens spherical surfaces. In the microlens array obtained here, the relationship between the lens curvature radius r and the diagonal lens pitch d is r = d / 2 = 12.7 μm.
It has exactly a hemispherical shape, and an alignment marker is formed in the same plane.
[0072]
(Sixth embodiment)
In the sixth embodiment, a polyimide layer is formed by applying polyamic acid on a 24 mm × 38 mm square quartz substrate by spin coating to a thickness of 12 μm and baking. Subsequently, an aluminum film is formed by electron beam evaporation. A photoresist is applied thereon, and 1064 × 808 circular aluminum patterns are formed at 18 μm intervals between adjacent patterns using semiconductor photolithography.
[0073]
Next, the polyimide layer is etched by reactive ion etching using the circular aluminum pattern as a mask to form 1064 × 808 cylindrical polyimide patterns with an interval of 18 μm between adjacent patterns.
[0074]
Next, the substrate is baked at 450 ° C. for 15 minutes to reflow the polyimide layer and form spherical protrusions. At this time, the contact angle between the resin spherical surface and the substrate is 120 degrees, the radius l of the spherical protrusion is 8.5 μm, and the height h of the spherical protrusion from the substrate is 4.2 μm. The diagonal spherical projection pitch d is 25.4 μm. The contact angle is controlled by controlling the thickness of the polyimide layer, the surface energy of the substrate, and the like. The surface energy of the substrate can be controlled by a method such as surface treatment of the substrate with a silane coupling agent having a functional group having fluorine to form a water repellent surface.
Next, a PSG (Phosphosilicate glass) layer is formed as a continuous film at 350 ° C. by atmospheric pressure CVD. Since the PSG layer is formed isotropically on the substrate and the resin surface and is performed until there is no plane portion between adjacent spherical surfaces, the thickness t of the continuous film is 4.2 μm. In this case, since the CVD layer (PSG continuous film) is isotropically laminated, the curvature of the resin formed after the reflow is maintained, and the radius of curvature is 15 μm.
[0076]
The structure obtained here can be used as it is as a microlens array. The relationship between the radius of curvature r of this microlens and the spherical protrusion pitch d in the diagonal direction is r = d / 2 = 12.7 μm.
And had exactly a hemispherical shape. As a result, a microlens array having a radius of curvature of 12.7 μm and no unused light area was obtained.
[0077]
【The invention's effect】
As described above, according to the present invention, an unused area between adjacent microstructures such as lenses can be reduced, and the curvature of the microstructure such as a lens can be increased. A microstructure array and a manufacturing method thereof could be realized.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a microlens array and a microlens array mold according to the present invention.
FIGS. 2A and 2B are a top view and a sectional view of a microlens array and a mold for the microlens array according to the first and third embodiments of the present invention. FIGS.
FIG. 3 is a top view of a microlens array and a microlens array mold according to a fourth embodiment of the present invention.
FIG. 4 is a top view of a microlens array and a microlens array mold according to a fifth embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Micro lens array, micro lens array metal mold | die 2 Substrate 3 Spherical protrusion 4 Continuous film 5 Alignment marker

Claims (35)

A micro structure having a plurality of cylindrical or spherical curved projections discretely arranged on a substrate in accordance with an arrangement of a desired micro structure array and a continuous film having a substantially uniform film thickness provided thereon. The contact angle between the curved projection and the substrate (the angle formed by the contact surface with respect to the curved projection and the substrate surface where the curved projection and the substrate contact each other and the angle on the curved projection side) is greater than 90 degrees , A microstructure structure in which adjacent curved projections are connected at the position of the maximum diameter of a curved surface by a continuous film . The curved protrusions are formed by patterning a thermoplastic material layer on a substrate in a desired shape according to the arrangement of the desired microstructure array, and deforming the patterned thermoplastic material layer in a discrete state by heat treatment. The microstructure array according to claim 1 , wherein the microstructure array is formed. Microstructure array according to claim 1 or 2, wherein the continuous film is characterized in that it is a plated or electrodeposited layer. 4. The microstructure array according to claim 3 , wherein the continuous film is an electroplated layer. 4. The microstructure array according to claim 3 , wherein the continuous film is an electroless plating layer. Microstructure array according to claim 1 or 2, wherein the continuous film is a layer formed by a chemical deposition method (CVD). Microstructure array according to claim 1 or 2, wherein the continuous film is characterized by a layer formed by vacuum deposition. Microstructure array according to claim 1 or 2, wherein the continuous film is characterized in that it consists of an inorganic material. 3. The microstructure array according to claim 1, wherein the continuous film is made of an organic material. Microstructure array according to any one of claims 1 to 9, characterized in that the shape of the curved surface protrusions are formed all the same. Microstructure array according to any one of claims 1 to 10, characterized in that said curved surface protrusions are regularly arranged. The microstructure array according to any one of claims 1 to 11 , wherein curved alignment protrusions for the alignment marker structure are also formed in an alignment marker region outside the array region for the microstructure array. 3. The microstructure array according to claim 1, wherein the substrate, the curved protrusion, and the continuous film are transparent. 14. The microstructure array according to claim 13 , wherein the microstructure array is a microlens array. The microstructure array according to any one of claims 1 to 12 , wherein the microstructure array is a mold for a microstructure array. The microstructure array according to claim 15 , wherein the microstructure array mold is a microlens array mold. A method for producing a microstructure array comprising:
(1) A plurality of cylindrical or spherical curved projections that are discretely arranged on the substrate in accordance with the arrangement of the desired microstructure array, and the contact angle between the curved projection and the substrate (where the curved projection and the substrate contact each other) A step of forming an angle between a contact surface with respect to the curved protrusion and the substrate surface at an angle on the curved protrusion side, which is larger than 90 degrees,
(2) forming a continuous film having a substantially uniform film thickness on the curved projection and the substrate so that adjacent curved projections are connected at the position of the maximum diameter of the curved surface ;
A method for manufacturing a microstructure array, comprising: The curved projections in the step (1) pattern the thermoplastic material layer on the substrate in a desired shape according to the arrangement of the desired microstructure array, and heat treat the patterned thermoplastic material layer in a discrete state. The method for producing a microstructure array according to claim 17 , wherein the microstructure structure is formed by being deformed. The method for producing a microstructure array according to claim 17 or 18 , wherein the continuous film in the step (2) is formed by plating or electrodeposition. 20. The method for manufacturing a microstructure array according to claim 19 , wherein the continuous film in the step (2) is formed by electroplating. 21. The method for manufacturing a microstructure array according to claim 19 , wherein in the step (2), an electrode layer is formed on the curved protrusion and electroplating or electrodeposition is performed. The method for manufacturing a microstructure array according to claim 19 , wherein the continuous film in the step (2) is formed by electroless plating. The method for producing a microstructure array according to claim 17 or 18 , wherein the continuous film of the step (2) is formed by chemical deposition (CVD). The method for producing a microstructure array according to claim 17 or 18 , wherein the continuous film in the step (2) is formed by vacuum deposition. The method for producing a microstructure array according to claim 17 or 18 , wherein the continuous film is made of an inorganic material. The method for producing a microstructure array according to claim 17 or 18 , wherein the continuous film is made of an organic material. 27. The method for manufacturing a microstructure array according to claim 17 , wherein in the step (1), the curved protrusions are all formed in the same shape. 28. The method of manufacturing a microstructure array according to claim 17 , wherein in the step (1), the curved protrusions are regularly arranged. In the step (1), according to any one of claims 17 to 28, characterized in that forming the curved projection for alignment markers structural in sequence region outside of the alignment marker region for microstructure array A method for manufacturing a microstructure array. The method of manufacturing a microstructure array according to claim 17 or 18 , wherein the substrate, the curved protrusion, and the continuous film are transparent. The method of manufacturing a microstructure array according to claim 30 , wherein the microstructure array is a microlens array. 30. The method for producing a microstructure array according to claim 17, wherein the microstructure array is a mold for a microstructure array. 33. The method for producing a microstructure array according to claim 32 , wherein the microstructure array mold is a microlens array mold. An image pickup apparatus comprising: a light receiving unit at a position corresponding to each lens of the microlens array according to claim 14 or the microlens array manufactured by using the manufacturing method according to claims 17 to 29 . Each pixel opening part enclosed by the light shielding layer was provided in the position corresponding to each lens of the microlens array produced using the microlens array of Claim 14 , or the production method of Claims 17 thru | or 29 . A display device characterized by that.

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