JP2010204635A - Lens array - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens array improving image quality by restraining the occurrence of ghost and flare. <P>SOLUTION: This lens array includes a base plate and a plurality of lenses provided to fill in a plurality of through-holes, respectively, arrayed in the base plate, wherein each inner peripheral surface of the through-holes has an anti-reflection structure. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lens array.

  In recent years, portable terminals of electronic devices such as mobile phones and PDAs (Personal Digital Assistants) are equipped with small and thin imaging units. Such an imaging unit generally includes a solid-state imaging device such as a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal-Oxide Semiconductor) image sensor, and a lens that forms a subject image on the solid-state imaging device. I have.

  With the downsizing / thinning of portable terminals and the widespread use of portable terminals, further reduction in size / thinning is required for imaging units mounted on the portable terminals, and productivity is required. In response to such a request, one or more lens arrays in which a plurality of lenses are arrayed are sequentially stacked on a sensor array in which a plurality of solid-state image sensors are arrayed, and the obtained stacked bodies are respectively combined with a solid-state image sensor and a lens. A method of mass-producing an imaging unit by cutting so as to include And as a lens array used for the said use, what was described, for example in patent documents 1-3 is known.

  In the lens arrays described in Patent Documents 1 and 2, a curable resin material is dropped on the surface of a parallel plate substrate formed of a light-transmitting material such as glass, and the resin material is shaped into a predetermined shape with a mold. A plurality of lenses are formed in a lump by curing them in a state of shaping. In addition, the lens array described in Patent Document 3 has a plurality of through holes formed in a silicon substrate, and separately formed spherical lens materials are arranged in the through holes, and these lens materials are bonded to the substrate by soldering. After polishing, a plurality of lenses are collectively formed.

Japanese Patent No. 3926380 International Publication No. 08/102648 US Pat. No. 6,426,829

  In the lens arrays described in Patent Documents 1 and 2, the lens includes a portion made of a curable resin material and a portion made of a substrate material having optical characteristics different from that of the curable resin material, and is reflected at the boundary between them. Produce. As a result, inconveniences in optical performance may occur such that flare and ghost are generated and image quality is deteriorated.

  Moreover, in the lens array described in Patent Document 3, the lens is made of a single material, and the boundary between materials having different optical characteristics is not formed inside the lens. On the other hand, the material is different between the substrate and the lens, A boundary where materials having different optical characteristics are in contact with each other is formed between the inner peripheral surface of the through hole of the substrate and the outer peripheral surface of the lens in contact with the inner peripheral surface. Then, reflection occurs at this boundary, and ghosts and flares are generated, which may reduce image quality.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a lens array capable of improving image quality by suppressing the occurrence of ghosts and flares.

  A lens array comprising a substrate and a plurality of lenses provided by filling each of the plurality of through holes arranged in the substrate, and having an antireflection structure on each inner peripheral surface of the through hole Lens array.

  According to the present invention, since the antireflection structure is provided on each inner peripheral surface of the through hole of the substrate, it is formed between the inner peripheral surface of the through hole and the outer peripheral surface of the lens in contact with the inner peripheral surface. Reflection at the boundary is prevented, and generation of ghosts and flares can be suppressed. Thereby, the image quality can be improved.

It is a figure which shows an example of an imaging unit for describing embodiment of this invention. It is a figure which shows an example of a lens array for describing embodiment of this invention. It is a figure which shows the lens array of FIG. 2 in the III-III line cross section. 4A to 4G are diagrams showing modifications of the lens array in FIG. 5A to 5D are diagrams illustrating an example of a method of manufacturing a substrate included in the lens array of FIG. It is a figure which shows an example of the shaping | molding die which shape | molds the lens included in the lens array of FIG. 7A to 7C are diagrams showing an example of a method for manufacturing a lens array using the mold shown in FIG. It is a figure which shows the modification of the manufacturing method of the lens array shown to FIG. 7A-FIG. 7C. It is a figure which shows an example of the shaping | molding die which shape | molds the lens included in the lens array of FIG. 4F. 10A and 10B are diagrams illustrating an example of a method for manufacturing the imaging unit in FIG. 11A to 11C are diagrams showing a modification of the method for manufacturing the imaging unit shown in FIGS. 10A and 10B. 12A and 12B are diagrams illustrating another example of a method for manufacturing the imaging unit in FIG. 13A to 13C are diagrams illustrating a modification of the method for manufacturing the imaging unit illustrated in FIGS. 12A and 12B.

  FIG. 1 shows an example of an imaging unit.

  As shown in FIG. 1, the imaging unit 1 includes a sensor module 2 including a solid-state imaging element 22 and a lens module 3 including a lens 32 that forms a subject image in a light receiving region of the solid-state imaging element 22. .

  The sensor module 2 has a wafer piece 21. The wafer piece 21 is made of, for example, a semiconductor material such as silicon, and has a substantially rectangular shape in plan view. A solid-state image sensor 22 is provided at a substantially central portion of the wafer piece 21. The solid-state imaging device 22 is, for example, a CCD image sensor, a CMOS image sensor, or the like, and repeats a well-known film formation process, photolithography process, etching process, impurity addition process, etc. A light receiving region, an electrode, an insulating film, a wiring, and the like are formed.

  The lens module 3 includes a substrate piece 31 and a lens 32. The substrate piece 31 is formed in a substantially rectangular shape in plan view that is substantially the same as the wafer piece 21 of the sensor module 2. A through hole 34 having a substantially circular shape in plan view that penetrates the substrate piece 31 in the thickness direction is formed in the central portion of the substrate piece 31. The lens 32 is provided so as to fill the through hole 34 and is supported by the substrate piece 31. The lens surfaces 33 respectively formed at both ends of the optical axis direction of the lens 32 are convex spherical surfaces in the illustrated example. However, depending on the application, convex spherical surfaces, concave spherical surfaces, aspherical surfaces, Or various combinations of planes can be taken.

  An antireflection structure is provided on the inner peripheral surface of the through hole 34. Thereby, reflection at the boundary formed between the inner peripheral surface of the through hole 34 and the outer peripheral surface of the lens 32 in contact with the inner peripheral surface is prevented, and the occurrence of ghost, flare, etc. is suppressed. This antireflection structure will be described later.

  On one surface of the substrate piece 31 (the lower surface in the figure), a leg portion 35 is projected. The leg portion 35 protrudes from the surface of the substrate piece 31 higher than the surface of the lens 32 exposed on the surface side of the substrate piece 31 on which the leg portion 35 is provided. The lens module 3 is laminated on the sensor module 2 by joining the leg portions 35 of the substrate piece 31 to the wafer piece 21 of the sensor module 2. The height H of the leg portion 35 from the surface of the substrate piece 31 provided with the leg portion 35 is set so that the lens 32 does not contact the sensor module 2. That is, the height H of the leg portion 35 from the surface of the substrate piece 31 is H> h with respect to the height h of the lens 32 from the surface of the substrate piece 31.

  As long as the lens module 3 is stabilized on the sensor module 2, the shape of the leg portion 35 is not particularly limited, but preferably, it is formed in a frame shape surrounding the lens 32 as in the illustrated example. If the leg portion 35 has a frame shape, the space between the wafer piece 21 of the sensor module 2 and the substrate piece 31 of the lens module 3 can be isolated from the outside. It is possible to prevent foreign matters such as the foreign matter from entering and adhering to the solid-state imaging device 22 or the lens 32. Further, in this case, for example, if the leg portion 35 is made opaque to visible light, unnecessary light incident on the solid-state imaging device 22 from between the wafer piece 21 and the substrate piece 31 may be blocked by the leg portion 35. it can.

  The imaging unit 1 configured as described above is typically reflow-mounted on a circuit board of a mobile terminal. That is, the circuit board is preliminarily printed with paste-like solder at a position where the imaging unit 1 is mounted, and the imaging unit 1 is placed on the circuit board, and the circuit board including the imaging unit 1 is irradiated with infrared rays. The imaging unit 1 is mounted on the circuit board by performing a heat treatment such as blowing hot air, thereby melting the solder.

  The imaging unit 1 described above has one lens module 3 stacked on the sensor module 2, but a plurality of lens modules 3 may be stacked on the sensor module 2. In this case, the upper lens module 3 laminated on the lens module 3 is laminated by bonding its leg portion 35 to the substrate piece 31 of the lower lens module 3, and the leg portion 35 of the upper lens module 3 is laminated. Is set so that the lens 32 does not contact the lower lens module 3.

  In the lens module 3, the leg portion 35 formed integrally with the substrate piece 31 is described as being joined to the sensor module 2 or another lens module 3 and stacked thereon. Instead of 35, the substrate piece 31 may be laminated via a separate spacer.

  2 and 3 show an example of a lens array.

  The lens array 5 shown in FIGS. 2 and 3 includes a substrate 30 and a plurality of lenses 32. The lens module 3 described above is obtained by cutting the substrate 30 and dividing the lens array 5 so as to include the lenses 32 individually. In other words, the lens array 5 is an assembly of the lens modules 3 described above.

  The substrate 30 has a wafer shape (circular shape), and has a plurality of through holes 34 penetrating in the thickness direction. The through holes 34 are arranged in a matrix in the illustrated example. Typically, the substrate 30 has a diameter of 6 inches, 8 inches, or 12 inches, and thousands of through holes 34 are arranged therein. The substrate 30 is not limited to a wafer shape, and may be a rectangular shape, for example. Further, the arrangement of the through holes 34 is not limited to a matrix, and may be, for example, a radial shape, a concentric annular shape, another two-dimensional arrangement, or a one-dimensional arrangement.

  An antireflection structure is provided on the inner peripheral surface of the through hole 34 as described in the imaging unit 1 described above. Examples of the antireflection structure include fine irregularities formed on the inner peripheral surface of the through hole 34 and an antireflection film that covers the inner peripheral surface of the through hole 34. Examples of the method of forming fine irregularities on the inner peripheral surface of the through hole 34, in other words, the roughening of the through hole 34 include blasting, etching, high temperature oxidation, polishing, laser processing, and the like. . In addition, as a method of forming the antireflection film on the inner peripheral surface of the through hole 34, a blacking process in which a black paint is applied can be exemplified. Even when the inner peripheral surface of the through hole 34 is covered with an antireflection film, the inner peripheral surface of the through hole 34 is a rough surface in order to improve the adhesion between the inner peripheral surface of the through hole 34 and the antireflection film. Also good.

  The lens 32 is provided by filling the through hole 34. The lens 32 provided by filling the through hole 34 can be formed entirely of a homogeneous material, and is excellent in optical performance. That is, on the optical axis of the lens 32, a boundary between materials having different optical characteristics such as refractive index is not formed, and inconveniences in optical performance such as reflection at the boundary and generation of flare and ghost due to the reflection are avoided.

  In the lens 32, the outer peripheral surface of the portion accommodated in the through hole 34 is in close contact with the inner peripheral surface of the through hole 34. Thereby, the bonding strength between the lens 32 and the substrate 30 is obtained. Since the bonding between the lens 32 and the substrate 30 is established, it is not necessary to individually bond the lens 32 to the substrate 30 by, for example, soldering, and the productivity is excellent. Here, as an antireflection structure provided on the inner peripheral surface of the through hole 34, when the inner peripheral surface of the through hole 34 is a rough surface, the surface roughness is preferably 4 μm in terms of 10-point average roughness (Rz). It is 25 μm or less. If it is only for preventing reflection, it may be 1 μm or more. However, by setting the above surface roughness range, the lens 32 and the substrate 30 are brought into close contact with the outer peripheral surface of the lens 32 and the inner peripheral surface of the through hole 34. The joint strength can be increased.

  Both end portions of the lens 32 in the optical axis direction protrude from the through holes 32, and extended portions 36 that overlap the peripheral portions of the through holes 34 on the surface of the substrate 30 are respectively provided at these end portions. . By sandwiching the substrate 30 between the pair of extending portions 36, further bonding strength between the lens 32 and the substrate 30 can be obtained. Even when the extending portion 36 is provided only at one end of the both end portions in the optical axis direction of the lens 32, the lens 32 and the substrate 30 are brought into close contact with the extending portion 36 and the surface of the substrate 30. Bond strength is obtained.

  In the example shown in the figure, the extending portion 36 is formed in a substantially circular shape in plan view, spreading from the end of the lens 32 protruding from the through hole 34 over the entire circumference, but is not limited thereto. The extending part 36 may be one that overlaps at least a part of the peripheral part of the through hole 34, and may be, for example, one or a plurality of small pieces extending radially from the end part of the lens 32. In any case, when d is the maximum value of the distance from the optical axis of the lens 32 to the edge of the extending portion 36 and r is the opening radius of the through-hole 34, the extension is achieved by satisfying d> r. The existing portion 36 overlaps the peripheral portion of the through hole 34 on the surface of the substrate 30.

  A plurality of leg portions 35 project from one surface of the substrate 30 (the lower surface in the drawing). The leg portions 35 are arranged in a matrix in the same arrangement as the through holes 34. The leg portion 35 is formed in a frame shape and surrounds the lens 32 filling the through hole 34.

  As described in the imaging unit 1, the leg portion 35 protrudes from the surface of the substrate 30 higher than the surface of the lens 32 exposed on the surface side of the substrate 30 on which the leg portion 35 is provided. That is, with respect to the height h of the lens 32 from the surface of the substrate 30, the height H of the leg portion 35 from the surface of the substrate 30 is H> h.

  4A to 4G each show a modification of the lens array of FIG.

  In the lens array 5 of the modification shown in FIG. 4A, both end portions of the lens 32 protrude from the through holes 34, and extending portions 36 are formed at both end portions. One lens surface 33 of the lens 32 is a concave spherical surface, and the other lens surface 33 is a convex spherical surface.

  In the modified lens array 5 shown in FIG. 4B, both end portions of the lens 32 protrude from the through holes 34, and extending portions 36 are formed at both end portions. Both lens surfaces 33 of the lens 32 are concave spherical surfaces.

  In the lens array 5 of the modified example shown in FIG. 4C, both end portions of the lens 32 protrude from the through holes 34, and extending portions 36 are formed at both end portions. One lens surface 33 of the lens 32 is an aspherical surface, and the other lens surface 33 is a convex spherical surface.

  In the lens array 5 of the modified example shown in FIG. 4D, both end portions of the lens 32 protrude from the through holes 34, and extending portions 36 are formed at both end portions. Both lens surfaces 33 of the lens 32 are aspherical surfaces.

  In the lens array 5 of the modified example shown in FIG. 4E, both end portions of the lens 32 protrude from the through holes 34, and extending portions 36 are formed at both end portions. One lens surface 33 of the lens 32 is an aspherical surface, and its central portion enters the through hole 34. The other lens surface 33 of the lens 32 is a convex spherical surface.

  In the lens array 5 of the modification shown in FIG. 4F, one end of the lens 32 is accommodated in the through hole 34, and only the other end projects from the through hole 34, and the end projects from the through hole 34. The extending part 36 is formed only in the part. One lens surface 33 of the lens 32 is a concave spherical surface, and the other lens surface 33 is a convex spherical surface.

  In the modified lens array 5 shown in FIG. 4G, one end of the lens 32 is accommodated in the through hole 34, and only the other end projects from the through hole 34, and the end projects from the through hole 34. The extending part 36 is formed only in the part. One lens surface 33 of the lens 32 is a concave spherical surface, and the other lens surface 33 is an aspherical surface.

  The combination of the shapes of the lens surfaces 33 formed at both ends of the optical axis direction of the lens 32 is not limited to those shown in FIGS. 4A to 4G, and a convex spherical surface or a concave spherical surface is used depending on the application. Various combinations of aspherical surfaces, or aspherical surfaces can be employed.

  By forming the through hole 34 in the substrate 30 and filling the through hole 34 to provide the lens 32, a part of one lens surface 33 of the lens 32 enters the through hole 34 as shown in FIG. 4E. As shown in FIGS. 4F and 4G, the lens shape is such that one lens surface 33 of the lens 32 and the end where the lens surface is formed are accommodated in the through hole 34. This also increases the degree of freedom in lens design. That is, depending on the lens design, the lens surface 33 may have an aspheric shape that can contact the substrate. Here, if the substrate 30 does not have the through hole 34 and it is intended to maintain such an aspherical shape as designed, the periphery of the portion of the lens surface 33 that can come into contact with the substrate 30 is made thicker. Although it is conceivable to avoid contact with the lens surface 33, the thickness of the entire lens increases and the lens 32 becomes larger. On the other hand, if it is going to avoid the enlargement of the lens 32, such an aspherical shape cannot be taken, and the freedom degree of lens design is restrict | limited. On the other hand, as described above, if the substrate 30 has the through hole 34, the lens surface 33 can be embedded in the through hole 34, and the lens design is not limited to the design in which the lens surface 33 does not contact the substrate 30. The degree of freedom is increased, and it is not necessary to make the lens 32 unnecessarily thick, and the lens 32 can be reduced in size (reduced in height).

  Hereinafter, an example of the manufacturing method of the lens array of FIG. 2 will be described.

  5A to 5D show an example of a method for manufacturing a substrate included in the lens array of FIG.

  In the example shown in FIGS. 5A to 5D, the substrate material 40 is blasted to form a plurality of through holes 34 and a plurality of legs 35, thereby obtaining the substrate 30. The substrate material 40 has the same outer shape as the substrate 30 and has the same thickness. Examples of the material for forming the substrate material 40 include silicon, glass, resin, and the like.

  As shown in FIG. 5A, a blast mask 41 that covers a portion where the leg portion 35 is formed is attached to one surface of the substrate material 40.

  As shown in FIG. 5B, blasting is performed from the surface side of the substrate material 40 to which the mask 41 is attached to a depth H (corresponding to the height of the leg portion 35), and the substrate material not covered with the mask 41 40 regions are removed. Thereby, the leg part 35 is formed.

  As shown in FIG. 5C, a blast mask 42 that exposes a portion where the through hole 34 is formed is attached to the other surface of the substrate material 40.

  As shown in FIG. 5D, blasting is performed from the surface side of the substrate material 40 to which the mask 42 is attached, and the region of the substrate material 40 not covered with the mask 42 is removed. Thereby, the through hole 34 is formed.

  Blasting makes it easy to control the surface roughness of the treated surface. If the through holes 34 are formed by blasting, the inner peripheral surface can be made rough. Therefore, an antireflection structure can be provided on the inner peripheral surface of the through hole 34 simultaneously with the formation of the through hole 34.

  In the above example, a blast mask is provided on the substrate material 40, and the through holes 34 and the leg portions 35 are formed by blasting the substrate material 40. Similarly, an etching mask is provided and etching is performed thereon. Through holes 34 and leg portions 35 can also be formed. And also by etching, the inner peripheral surface of the through-hole 34 can be roughened, that is, the anti-reflection structure can be provided on the inner peripheral surface simultaneously with the formation of the through-hole 34.

  FIG. 6 shows an example of a mold for molding a lens included in the lens array of FIG.

  A molding die 50 shown in FIG. 6 is for molding a molding material into a lens 32 included in the lens array 5 of FIG. 2, and includes an upper die 51 and a lower die 52.

  On the facing surface of the upper mold 51 facing the lower mold 52, lens molding surfaces 53 having a shape obtained by inverting one lens surface 33 of the lens 32 are arranged in the same arrangement as the arrangement of the lenses 32 in the lens array 5. .

  On the facing surface of the lower mold 52 facing the upper mold 51, lens molding surfaces 54 having a shape obtained by inverting the other lens surface 33 of the lens 32 are arranged in the same arrangement as the arrangement of the lenses 32 in the lens array 5. . In addition, on the opposing surface of the lower mold 52, accommodation portions 55 that accommodate the leg portions 35 of the substrate 30 are formed.

  The upper mold 51 and the lower mold 52 sandwich the substrate 30 therebetween. The lens molding surface 53 of the upper mold 51 and the lens molding surface 54 of the lower mold 52, and the inner peripheral surface of the through hole 54 of the substrate 30 positioned between the lens molding surfaces 53, 54, A cavity C for molding the lens 32 is formed.

  The upper mold 51 is formed with an annular recess 56 positioned on the periphery of the through hole 34 on the surface side of the substrate 30 in contact with the upper mold 51. The lower mold 52 is formed with an annular recess 57 extending below the peripheral portion of the through hole 34 on the surface side of the substrate 30 in contact with the lower mold 52. The recesses 56 and 57 both communicate with the cavity C.

  As a material for forming the lens 32, for example, an energy curable resin composition can be suitably used. The energy curable resin composition may be either a resin composition that is cured by heat or a resin composition that is cured by irradiation with active energy rays (for example, ultraviolet rays or electron beam irradiation).

  The resin composition forming the lens 32 preferably has appropriate fluidity before curing from the viewpoint of moldability, such as mold shape transfer suitability. Specifically, it is liquid at room temperature and has a viscosity of about 1000 to 50000 mPa · s.

  Moreover, it is preferable that the resin composition which forms the lens 32 has a heat resistance that does not cause thermal deformation even after the reflow process after curing. From this viewpoint, the glass transition temperature of the cured product is preferably 200 ° C. or higher, more preferably 250 ° C. or higher, and particularly preferably 300 ° C. or higher. In order to impart such high heat resistance to the resin composition, it is necessary to constrain the mobility at the molecular level, and as effective means, (1) means for increasing the crosslinking density per unit volume, (2) Means utilizing a resin having a rigid ring structure (for example, an alicyclic structure such as cyclohexane, norbornane, tetracyclododecane, an aromatic ring structure such as benzene and naphthalene, a cardo structure such as 9,9′-biphenylfluorene, Resins having a spiro structure such as spirobiindane, specifically, for example, JP-A-9-137043, JP-A-10-67970, JP-A-2003-55316, JP-A-2007-334018, JP-A-2007-238883 (3) means for uniformly dispersing a substance having a high Tg such as inorganic fine particles (for example, JP-A-5-209) 027, 10-298265, etc.). A plurality of these means may be used in combination, and it is preferable to make adjustments within a range that does not impair other characteristics such as fluidity, shrinkage rate, and refractive index characteristics.

  The resin composition forming the lens 32 is preferably a resin composition having a small volume shrinkage due to the curing reaction from the viewpoint of shape transfer accuracy. The curing shrinkage rate of the resin composition is preferably 10% or less, more preferably 5% or less, and particularly preferably 3% or less. Examples of the resin composition having a low curing shrinkage rate include (1) resin compositions containing a high molecular weight curing agent (such as a prepolymer) (for example, JP-A Nos. 2001-19740, 2004-302293, and 2007-). The number average molecular weight of the high molecular weight curing agent is preferably in the range of 200 to 100,000, more preferably in the range of 500 to 50,000, and particularly preferably in the range of 1,000 to 20, as described in Japanese Patent No. 211247. The value calculated by the number average molecular weight of the curing agent / the number of curing reactive groups is preferably in the range of 50 to 10,000, and in the range of 100 to 5,000. More preferably, it is particularly preferably in the range of 200 to 3,000.), (2) Resins containing non-reactive substances (organic / inorganic fine particles, non-reactive resins, etc.) Composition (for example, described in JP-A-6-298883, JP-A-2001-247793, JP-A-2006-225434, etc.), (3) a resin composition containing a low shrinkage crosslinking reactive group (for example, ring-opening polymerization) Sex groups (for example, epoxy groups (for example, described in JP-A No. 2004-210932), oxetanyl groups (for example, described in JP-A No. 8-134405), episulfide groups (for example, JP-A No. 2002-105110) Etc.), cyclic carbonate groups (e.g. described in JP-A-7-62065 etc.), etc., ene / thiol curing groups (e.g. described in JP-A 2003-20334 etc.), hydrosilylation curing groups (e.g. (For example, described in JP-A-2005-15666), etc.), (4) rigid skeleton resins (fluorene, adamantane, isophorone, etc.) (5) Resin composition containing an interpenetrating network structure (so-called IPN structure) containing two types of monomers having different polymerizable groups (for example, described in JP-A-9-137043) For example, described in JP-A-2006-131868), (6) Resin composition containing an expansible substance (for example, described in JP-A-2004-2719, JP-A-2008-238417, etc.), etc. Can be suitably used in the present invention. In addition, it is preferable from the viewpoint of optimizing physical properties to use a plurality of curing shrinkage reducing means in combination (for example, a resin composition containing a prepolymer containing a ring-opening polymerizable group and fine particles).

  Further, the resin composition forming the lens 32 is desirably a mixture of two or more types of resins having different Abbe numbers. The resin on the high Abbe number side preferably has an Abbe number (νd) of 50 or more, more preferably 55 or more, and particularly preferably 60 or more. The refractive index (nd) is preferably 1.52 or more, more preferably 1.55 or more, and particularly preferably 1.57 or more. Such a resin is preferably an aliphatic resin, particularly a resin having an alicyclic structure (for example, a resin having a cyclic structure such as cyclohexane, norbornane, adamantane, tricyclodecane, tetracyclododecane, specifically, for example, JP-A-10-152551, JP-A-2002-212500, JP-A-2003-20334, JP-A-2004-210932, JP-2006-199790, JP-2007-2144, JP-2007-284650. And the resin described in JP-A-2008-105999. The resin on the low Abbe number side preferably has an Abbe number (νd) of 30 or less, more preferably 25 or less, and particularly preferably 20 or less. The refractive index (nd) is preferably 1.60 or more, more preferably 1.63 or more, and particularly preferably 1.65 or more. As such a resin, a resin having an aromatic structure is preferable. For example, a resin having a structure such as 9,9′-diarylfluorene, naphthalene, benzothiazole, benzotriazole and the like (specifically, for example, JP-A-60-38411). Publication No. 10-67977, No. 2002-47335, No. 2003-238842, No. 2004-83855, No. 2005-325331, No. 2007-238883, International Publication 2006. / 095610 publication, Japanese Patent No. 2537540 publication, etc.) are preferable.

  Further, in the resin composition forming the lens 32, it is preferable to disperse the inorganic fine particles in the matrix in order to increase the refractive index or adjust the Abbe number. Examples of the inorganic fine particles include oxide fine particles, sulfide fine particles, selenide fine particles, and telluride fine particles. More specifically, for example, fine particles of zirconium oxide, titanium oxide, zinc oxide, tin oxide, niobium oxide, cerium oxide, aluminum oxide, lanthanum oxide, yttrium oxide, zinc sulfide, and the like can be given. In particular, it is preferable to disperse fine particles such as lanthanum oxide, aluminum oxide, and zirconium oxide for the high Abbe number resin, and titanium oxide, tin oxide, zirconium oxide, and the like for the low Abbe number resin. It is preferable to disperse the fine particles. The inorganic fine particles may be used alone or in combination of two or more. Moreover, the composite by several components may be sufficient. In addition, for various purposes such as reducing photocatalytic activity and water absorption, the inorganic fine particles are doped with different metals, the surface layer is coated with different metal oxides such as silica and alumina, silane coupling agents and titanate cups. The surface may be modified with a ring agent, an organic acid (carboxylic acid, sulfonic acid, phosphoric acid, phosphonic acid, etc.) or a dispersant having an organic acid group. The number average particle size of the inorganic fine particles is usually about 1 nm to 1000 nm, but if it is too small, the properties of the substance may change. If it is too large, the influence of Rayleigh scattering becomes remarkable, so 1 nm to 15 nm is preferable. 2 nm to 10 nm are more preferable, and 3 nm to 7 nm are particularly preferable. Further, it is desirable that the particle size distribution of the inorganic fine particles is narrow. There are various ways of defining such monodisperse particles. For example, a numerical value range as described in JP-A No. 2006-160992 applies to a preferable particle size distribution range. Here, the above-mentioned number average primary particle size can be measured by, for example, an X-ray diffraction (XRD) apparatus or a transmission electron microscope (TEM). The refractive index of the inorganic fine particles is preferably 1.90 to 3.00, more preferably 1.90 to 2.70, and more preferably 2.00 to 2.70 at 22 ° C. and a wavelength of 589 nm. It is particularly preferred that The content of the inorganic fine particles with respect to the resin is preferably 5% by mass or more, more preferably 10 to 70% by mass, and particularly preferably 30 to 60% by mass from the viewpoint of transparency and high refractive index.

  In order to uniformly disperse the fine particles in the resin composition, for example, a dispersant containing a functional group having reactivity with a resin monomer that forms a matrix (for example, described in Examples of JP 2007-238884 A), hydrophobic Block copolymer composed of a functional segment and a hydrophilic segment (for example, described in JP-A-2007-2111164), or having a functional group capable of forming an arbitrary chemical bond with inorganic fine particles at the polymer terminal or side chain It is desirable to disperse the fine particles by appropriately using a resin (for example, described in JP 2007-238929 A, JP 2007-238930 A, etc.).

  In addition, the resin composition forming the lens 32 is appropriately mixed with known release agents such as silicone-based, fluorine-based, and long-chain alkyl group-containing compounds and additives such as antioxidants such as hindered phenols. May be.

  Moreover, a curing catalyst or an initiator can be mix | blended with the resin composition which forms the lens 32 as needed. Specifically, for example, a compound that accelerates a curing reaction (radical polymerization or ionic polymerization) by the action of heat or active energy rays described in JP-A-2005-92099 (paragraph numbers [0063] to [0070]) and the like. Can be mentioned. The amount of these curing reaction accelerators to be added varies depending on the type of catalyst and initiator, or the difference in the curing reactive site, and cannot be specified unconditionally, but in general, the total solid content of the curing reactive resin composition About 0.1-15 mass% is preferable with respect to a minute, and about 0.5-5 mass% is more preferable.

  The resin composition forming the lens 32 can be produced by appropriately blending the above components. At this time, if other components can be dissolved in the liquid low molecular weight monomer (reactive diluent), etc., it is not necessary to add a separate solvent, but if this is not the case, use a solvent. A curable resin composition can be produced by dissolving each component. The solvent that can be used in the curable resin composition is not particularly limited as long as the composition is uniformly dissolved or dispersed without precipitation, and specifically, for example, Ketones (eg, acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), esters (eg, ethyl acetate, butyl acetate, etc.), ethers (eg, tetrahydrofuran, 1,4-dioxane, etc.) Alcohols (eg, methanol, ethanol) Isopropyl alcohol, butanol, ethylene glycol, etc.), aromatic hydrocarbons (eg, toluene, xylene, etc.), water and the like. When the curable composition contains a solvent, it is preferable to perform a mold shape transfer operation after drying the solvent.

  When the energy curable resin composition is used as a molding material for forming the lens 32, the materials of the upper mold 51 and the lower mold 52 are appropriately selected according to the resin composition. That is, when a thermosetting resin composition is used as the resin composition, a metal material having excellent thermal conductivity, such as nickel, or a material that transmits infrared rays, such as glass, is used as the mold material. In addition, when an ultraviolet curable material is used as the resin material, the mold material is, for example, a material that transmits ultraviolet rays such as glass, and when the resin material is an electron beam curable material. The material of the mold is a material that transmits the electron beam.

  7A to 7C show an example of a method for manufacturing a lens array using the mold shown in FIG.

  As shown in FIG. 7A, the substrate 30 is set on the lower mold 52. The leg portion 35 of the substrate 30 is accommodated in the accommodating portion 55 of the lower mold 52, and the through hole 34 of the substrate 30 is disposed on the lens molding surface 54 of the lower mold 52. Then, the molding material M for forming the lens 32 is supplied to the inner peripheral surface of the through hole 34 of the substrate 30 and the concave portion formed by the lens molding surface 54 of the lower mold 52.

  As shown in FIG. 7B, the upper mold 51 is lowered. As the upper mold 51 is lowered, the molding material M is pressurized between the lens molding surface 53 of the upper mold 51 and the lens molding surface 54 of the lower mold 52 and is deformed following the lens molding surfaces 53 and 54. At the same time, it is in close contact with the inner peripheral surface of the through hole 34.

  As shown in FIG. 7C, the cavity C is filled with the molding material M in a state where the upper mold 51 is lowered and the molding mold 50 is closed. A recess 57 provided in the lower mold 52 and communicating with the cavity C is also filled with the molding material M. Then, an excessive molding material M enters the recess 56 provided in the upper mold 51 and communicating with the cavity C. Some variation occurs in the supply amount of the molding material M, but this variation is absorbed by the concave portion 56 of the upper mold 51.

  In this state, the molding material M is cured by appropriately applying energy for curing, and the lens 32 is formed. The molding material M that has entered the recesses 56 and 57 is cured to form the extended portion 36 of the lens 32.

  In this way, the molding material M is disposed in the through hole 34 of the substrate 30, and the molding material M is compression molded into the lens 32 in the through hole 34, thereby filling the through hole 34 and the inner periphery of the through hole 34. The lens 32 can be formed in a state of being in close contact with the surface.

  FIG. 8 shows a modification of the manufacturing method of the lens array shown in FIGS. 7A to 7C.

  As shown in FIG. 8, when the molding material M shrinks during curing, the upper mold 51 is lowered to a position where a predetermined gap g is left between the molding material M and the lower mold 52. At this time, the molding material M is in contact with the entire lens molding surface 53 of the upper mold 51 and the lens molding surface 54 of the lower mold 52. In this state, curing of the molding material M is started. Although the molding material M contracts as the curing progresses, the upper mold 51 is caused to follow the curing contraction of the molding material M by leaving a gap g between the upper mold 51 and the lower mold 52. Can be lowered. Therefore, it is possible to maintain pressure between the molding material M and the lens molding surface 53 of the upper mold 51 and continue to apply pressure to the molding material M. Thereby, the lens 32 in which the shapes of the lens molding surface 53 of the upper mold 51 and the lens molding surface 54 of the lower mold 52 are accurately transferred can be obtained. The lowering of the upper mold 51 following the curing shrinkage of the molding material M can be performed by the weight of the upper mold 51, for example.

  FIG. 9 is a view showing an example of a molding die for molding a lens included in the lens array of FIG. 4F.

  A molding die 50 shown in FIG. 9 compresses a molding material and molds it into lenses 32 included in the lens array 5 of FIG. 4F. Since one end of the lens 32 is accommodated in the through hole 34 of the substrate 30, the upper mold 51 is provided with a columnar protrusion 58 that enters the through hole 34, and the tip of the protrusion 58. A lens molding surface 53 is provided. The lower mold 52 is the same as that of the mold 50 in FIG.

  A gap 59 is placed between the outer peripheral surface of the protrusion 58 and the inner peripheral surface of the through hole 34 over the entire circumference. The gap 59 communicates with the cavity C, and absorbs excess molding material in the same manner as the concave portion 56 in the molding die 50 of FIG. Furthermore, even if there is a slight error between the positional accuracy (pitch accuracy) of the plurality of through-holes 34 and the positional accuracy (pitch accuracy) of the plurality of protrusions 58, the gap 59 allows The protrusions 58 can enter the corresponding through holes 34. When a large number (hundreds to thousands) of lenses 32 are formed at a time, the gap 59 is preferably 3 μm or more.

  In the lens array 5 manufactured as described above, the substrate 30 is cut with a cutter or the like and separated into a plurality of lens modules 3 each including a lens 32. The separated lens module 3 constitutes the imaging unit 1 in combination with the sensor module 2 as described above.

  10A and 10B show an example of a method for manufacturing the imaging unit of FIG.

  In the example shown in FIGS. 10A and 10B, the lens array 5 is separated into lens modules 3, and the lens modules 3 are stacked on the sensor module 2 to manufacture the imaging unit 1. As shown in FIG. 10A, the substrate 30 of the lens array 5 is cut along the cutting lines L so as to individually include the lenses 32 and the legs 35, and separated into the lens modules 3. Then, as shown in FIG. 10B, the individual lens modules 3 are stacked on the sensor module 2 via the leg portions 35 included therein to obtain the imaging unit 1.

  Thus, in each lens module 3, since the leg portion 35 is integrally formed on the substrate piece 31, no separate spacer is required. Therefore, the step of stacking the lens module 3 on the sensor module 2 is performed. Simplified. Thereby, the productivity of the imaging unit 1 can be improved.

  11A to 11C show a modification of the method for manufacturing the imaging unit shown in FIGS. 10A and 10B.

  In the example shown in FIGS. 11A to 11C, two lens modules 3 are stacked on the sensor module 2. As shown in FIG. 11A, one lens array 5 is stacked on another lens array 5 via a plurality of leg portions 35 included therein, thereby forming a lens array stack 6. Then, as shown in FIG. 11B, the laminated body 6 is formed along the cutting lines L so as to individually include a group of a plurality of lenses 32 arranged in the lamination direction and a group of a plurality of leg portions 35 arranged in the lamination direction. The substrates 30 of the two lens arrays 5 included are cut together and separated into a lens module laminate 7 in which two lens modules 3 are laminated. Then, as illustrated in FIG. 11C, the individual lens module stacks 7 are stacked on the sensor module 2 via the leg portions 35 of the lowermost lens module 3 to obtain the imaging unit 1.

  As described above, when the lens module stack 7 in which the plurality of lens modules 3 are stacked in advance is stacked on the sensor module 2, imaging is performed as compared with the case where the lens modules 3 are sequentially stacked on the sensor module 2. The productivity of the unit 1 can be improved.

  12A and 12B show another example of a method for manufacturing the imaging unit of FIG.

  In the example shown in FIG. 12A and FIG. 12B, the lens array 5 is stacked on the sensor array 4 to configure a plurality of imaging units 1 in a lump and are separated into individual imaging units 1.

  First, the sensor array 4 will be described. The sensor array 4 includes a wafer 20 formed of a semiconductor material such as silicon. The wafer 20 includes a plurality of lenses arranged in the same arrangement as the lenses 32 in the lens array 5. Are arranged. Typically, the diameter of the wafer 20 is 6 inches, 8 inches, or 12 inches, and thousands of solid-state image sensors 22 are arranged therein.

  As shown in FIG. 12A, the lens array 5 is laminated on the sensor array 4 via a plurality of legs 35 included therein, thereby forming an element array laminate 8. Then, as shown in FIG. 12B, the sensor array 4 included in the element array stacked body 8 along each cutting line L so as to individually include the solid-state imaging elements 22 and the lenses 32 and the legs 35 arranged in the stacking direction. The wafer 20 and the substrate 30 of the lens array 5 are cut together and separated into the imaging unit 1.

  13A to 13C show a modification of the method for manufacturing the imaging unit shown in FIGS. 12A and 12B.

  In the example illustrated in FIGS. 13A to 13C, two lens arrays 5 are stacked on the sensor array 4. As shown in FIG. 13A, one lens array 5 is stacked on another lens array 5 via a plurality of legs 35 included therein, thereby forming a lens array stack 6. Then, as shown in FIG. 13B, the lens array stacked body 6 is stacked on the sensor array 4 via a plurality of legs 35 included in the lowermost lens array 5 to form an element array stacked body 8. Then, as shown in FIG. 13C, along each cutting line L so as to individually include a group of solid-state imaging elements 22 and a plurality of lenses 32 arranged in the stacking direction and a group of a plurality of legs 35 arranged in the stacking direction. Then, the wafer 20 of the sensor array 4 and the substrate 30 of the two lens arrays 5 included in the element array stack 8 are cut together and separated into the imaging unit 1.

  In this way, one or a plurality of lens arrays 5 are stacked on the sensor array 4, and then the wafer 20 of the sensor array 4 and the substrate 30 of the plurality of lens arrays 5 are cut together to form a plurality of imaging units 1. As a result, the productivity of the imaging unit 1 can be further improved as compared with the case where the separated lens module 3 or the laminated body 7 thereof is assembled to the sensor module 2.

  As described above, the lens array disclosed in the present specification is a lens array including a substrate and a plurality of lenses provided by filling each of the plurality of through holes arranged in the substrate. In addition, each of the through holes has an antireflection structure on the inner peripheral surface thereof.

  Further, in the lens array disclosed in the present specification, the antireflection structure is unevenness formed on the inner peripheral surface.

  In the lens array disclosed in the present specification, the surface roughness of the inner peripheral surface is 4 μm or more and 25 μm or less in terms of 10-point average roughness (Rz).

  In the lens array disclosed in the present specification, the antireflection structure is an antireflection film that covers the inner peripheral surface.

  In the lens array disclosed in this specification, the antireflection film is a coating film of black paint.

  In addition, in the method for manufacturing a lens array disclosed in the present specification, a plurality of through-holes that are formed by arranging a plurality of through-holes having a rough inner peripheral surface on a substrate by blasting are arranged. A plurality of lenses are provided on the substrate so as to fill each of the substrates.

  In the lens array manufacturing method disclosed in this specification, the surface roughness of the inner peripheral surface is 10 μm or more and 4 μm or more and 25 μm or less in terms of average roughness (Rz).

  The lens array laminate disclosed in this specification includes a plurality of any of the lens arrays described above, and these lens arrays are sequentially laminated.

  In addition, an element array stack disclosed in the present specification includes at least one of the lens arrays described above and a sensor array in which a plurality of solid-state imaging elements are arranged on a wafer, and the lens array includes the lens array. They are sequentially stacked on the sensor array.

  Further, in the lens module manufacturing method disclosed in the present specification, any one of the lens arrays described above is divided so as to individually include one lens.

  Also, in the method for manufacturing a lens module laminate disclosed in this specification, the lens array laminate is divided so as to individually include the plurality of lenses arranged in the stacking direction.

  Further, in the manufacturing method of the imaging unit disclosed in this specification, the element array stacked body is divided so as to individually include the solid-state imaging elements and at least one lens arranged in the stacking direction.

DESCRIPTION OF SYMBOLS 1 Imaging unit 2 Sensor module 3 Lens module 4 Sensor array 5 Lens array 6 Lens array laminated body 7 Lens module laminated body 8 Element array laminated body 20 Wafer 21 Wafer piece 22 Solid-state image sensor 30 Substrate 31 Substrate piece 32 Lens 33 Lens surface 34 Through hole 35 Leg 36 Extension 40 Substrate material 41 Mask 42 Mask 50 Mold 51 Upper mold 52 Lower mold 53 Lens molding surface 54 Lens molding surface 55 Housing 56 Recess 57 Recess C Cavity M Molding material

Claims (12)

A lens array comprising a substrate and a plurality of lenses provided by filling each of the plurality of through holes arranged in the substrate,
A lens array having an antireflection structure on each inner peripheral surface of the through hole. The lens array according to claim 1,
The antireflection structure is a lens array that is unevenness formed on the inner peripheral surface. The lens array according to claim 2, wherein
The surface roughness of the inner peripheral surface is a lens array having a 10-point average roughness (Rz) of 4 μm or more and 25 μm or less. The lens array according to claim 1,
The antireflection structure is a lens array which is an antireflection film covering the inner peripheral surface. The lens array according to claim 4,
The antireflection film is a lens array which is a coating film of black paint. The substrate is formed by arranging a plurality of through holes whose inner peripheral surface is a rough surface by blasting,
A method of manufacturing a lens array, wherein a plurality of lenses are provided on the substrate so as to fill each of the plurality of arranged through holes. A method of manufacturing a lens array according to claim 6,
The inner peripheral surface has a ten-point average roughness (Rz) of 4 μm or more and 25 μm or less.   A lens array laminate comprising a plurality of the lens arrays according to claim 1, wherein the lens arrays are sequentially laminated.   A lens array according to any one of claims 1 to 5, and a sensor array in which a plurality of solid-state imaging elements are arranged on a wafer, wherein the lens array is sequentially stacked on the sensor array. Element array laminate.   A method for manufacturing a lens module, wherein the lens array according to any one of claims 1 to 5 is divided so as to individually include one lens.   A method for manufacturing a lens module laminate, wherein the lens array laminate according to claim 8 is divided so as to individually include a plurality of the lenses arranged in a lamination direction.   The manufacturing method of the imaging unit which divides | segments the element array laminated body of Claim 9 so that the said solid-state image sensor arranged in a lamination direction and at least 1 said lens may be included individually.

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