JP2008311354A - Imaging element, manufacturing method of barrier wall structure of imaging element, and image detection unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging element having a relatively high strength light-shielding structure. <P>SOLUTION: The imaging element includes a plurality of photodetectors arrayed on a photodetection surface, a barrier base portion formed between the plurality of photodetectors on the photodetection surface, and light-shielding barriers formed on a top surface of the barrier base portion. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image sensor having a structure for blocking obliquely incident light.

2. Description of the Related Art Conventionally, in order to prevent crosstalk of light, an image sensor having a light blocking structure for obliquely incident light in front of a light receiving surface is known. For example, Patent Document 1 discloses an example of an image sensor having a lattice frame structure for shielding oblique incident light.
JP 2005-352345 A

  However, an imaging device having a light blocking structure for obliquely incident light has room for improvement in that the structure of the light blocking structure is fragile and is easily broken during transportation or mounting, making it difficult to handle.

  The present invention is to solve the above-mentioned problems of the prior art. An object of the present invention is to provide an imaging device having a light shielding structure with relatively high strength.

  An imaging device according to a first embodiment of the present invention is formed on a plurality of light receiving elements arranged on a light receiving surface, a partition base formed between the plurality of light receiving elements on the light receiving surface, and an upper surface of the partition base. And a light-shielding partition wall.

  In the first embodiment, the width in the direction parallel to the light receiving surface of the partition wall is preferably smaller than the width in the direction parallel to the light receiving surface on the upper surface of the partition wall base.

  In the first embodiment, each of the plurality of light receiving elements has a lens that focuses the light receiving element. And it is preferable that the upper surface of a partition base is higher than the top part of a lens.

  The manufacturing method of the partition structure of the image pick-up element which concerns on the 2nd form of this invention is equipped with a 1st process and a 2nd process. In the first step, a partition base is formed between the plurality of light receiving elements on the light receiving surface by attaching and curing the first resin on the light receiving surface of the imaging element in which the plurality of light receiving elements are arranged. In the second step, the second resin is attached to the upper surface of the partition wall base and the second resin is cured, thereby forming the partition wall standing on the partition wall base.

  In the second embodiment, the first resin and the second resin are different resins, and it is preferable that the second resin has a higher light shielding property than the first resin when each is in a cured state.

  In the second embodiment, an on-chip lens is arranged for each light receiving element on the light receiving surface of the imaging element, and the height of the upper surface of the partition wall base is formed at a position higher than the top of the on-chip lens. It is preferable that

  In the second embodiment, it is preferable that the width of the partition wall be smaller than the width of the upper surface of the partition wall base.

  In the second embodiment, in the second step, the mold material having a cavity corresponding to the partition wall is disposed in contact with the upper surface of the partition wall base, and the partition wall is formed by injecting the second resin into the cavity. Is preferred.

  In the second embodiment, it is preferable that the second step is repeated a plurality of times so that the partition wall is laminated on the partition base.

  Here, an image sensor including the partition wall base and the partition wall formed by the manufacturing method of the second embodiment is also included in the technical scope of the present invention. In addition, an image detection unit including the image sensor according to the first embodiment or the second embodiment is also included in the technical scope of the present invention.

  In the present invention, it is possible to make the partition formed on the image sensor difficult to break.

(Description of the first embodiment)
FIG. 1 is a perspective view showing an image detection unit of the first embodiment. FIG. 2 is a cross-sectional view showing the configuration of the image detection unit.

  As shown in FIG. 1A, the image detection unit 11 is disposed on the image space side of the photographing optical system 12. The image detection unit 11 can be applied to both an imaging device that captures a recorded image and a focus detection unit that performs focus detection of the photographing optical system 12.

  As shown in FIG. 1B, the image detection unit 11 includes a microlens array 13 and an image sensor 14. The microlens array 13 is disposed in front of the light receiving surface of the image sensor 14 in the assembled state of the image detection unit 11. The microlens array 13 has a plurality of microlenses 13a arranged two-dimensionally. Each microlens 13a forms a subject image in a small area of the light receiving surface of the image sensor 14 partitioned by a partition structure 15 described later.

  The imaging element 14 has a light receiving surface on which a plurality of light receiving elements 14a are two-dimensionally arranged. On this light receiving surface, a space for layout of a partition wall structure (15), which will be described later, is provided in advance in the space between the light receiving elements 14a. A condensing lens 14b is disposed on-chip in front of each light receiving element 14a. FIG. 3 is a cross-sectional view showing the configuration of the image sensor 14.

  Further, on the light receiving surface side of the image sensor 14, a partition structure 15 having a light shielding property is provided. The partition wall structure 15 is located between the microlens array 13 and the image sensor 14 in the assembled state of the image detection unit 11. The partition wall structure 15 partitions the light receiving surface of the image sensor 14 into square lattice-like small regions (5 × 5 in the drawing). Each small region in the image sensor 14 includes a plurality of light receiving elements 14a. In the drawing, an example in which the light receiving element 14a of 7 × 7 pixels is arranged in one small region is shown for convenience.

  The small regions of the partition wall structure 15 correspond one-to-one with the microlenses 13 a of the microlens array 13 in the assembled state of the image detection unit 11. That is, the partition wall structure 15 serves to prevent crosstalk by blocking obliquely incident light from the microlenses 13a corresponding to adjacent small regions in each small region of the image detection unit 11.

  Here, each of the partition structures 15 includes a partition base 15a and a partition 15b made of resin. The bottom surface of the partition base portion 15 a is joined to the light receiving surface of the image sensor 14. The height from the bottom surface to the top surface of the partition wall base 15a is set to be higher than the position from the light receiving surface to the top of the condenser lens 14b.

  A partition wall 15b is erected on the upper surface of the partition base portion 15a. The thickness of the partition wall 15b (width in the direction parallel to the light receiving surface) is set to be smaller than the thickness of the upper surface of the partition wall base portion 15a (width in the direction parallel to the light receiving surface). Accordingly, a step is formed at the partition 15b and the partition base 15a in the partition structure 15. As an example, the height of the partition wall 15b is set to about 60 μm, and the thickness of the partition wall 15b is set to 10 μm.

  Moreover, the partition base 15a in the first embodiment is formed of a light curable resin having translucency such as an ultraviolet curable resin, for example. On the other hand, the partition wall 15b in the first embodiment is formed of a resin material in which a pigment dye such as carbon black is dispersed. Therefore, the partition wall 15b in the first embodiment has a higher light shielding property than the partition wall base portion 15a. In addition, since the height of the partition wall base portion 15a in the first embodiment is slightly higher than the condenser lens 14b of the image sensor 14, even if the light shielding property at the partition wall base portion 15a is low, there is almost no optical influence. It is not expected to occur.

  Next, the manufacturing process of the partition structure 15 in the first embodiment will be specifically described.

  In the first step, the condenser lens 14b and the partition wall base 15a are formed on the substrate of the image sensor 14 on which the light receiving element 14a is formed (see FIG. 4). As shown in FIG. 4A, a layout space for the partition wall structure 15 is formed in advance on the substrate of the image sensor 14 in the space between the light receiving elements 14a. The top of each condenser lens 14b formed in the first step is adjusted to be lower than the height of the upper surface of the partition wall base 15a.

Here, in an example of the first step, the condenser lens 14b and the partition wall base 15a are formed by the following procedures (1) to (4).
(1) An ultraviolet curable resin is uniformly applied to the substrate of the image sensor 14. In addition, in order to suppress the deformation | transformation in the formation process of the below-mentioned condensing lens 14b, it is preferable to select material with high heat resistance for this ultraviolet curable resin.
(2) A photomask corresponding to the shape of the partition wall base 15a is prepared, and the substrate (1) is irradiated with ultraviolet rays through the photomask. Thereby, the ultraviolet curable resin of the part corresponding to the partition base 15a on the substrate is selectively cured.
(3) Thereafter, the uncured ultraviolet curable resin on the substrate is washed away. As a result, the partition base 15a made of the cured ultraviolet curable resin remains on the substrate. This state is shown in FIG.
(4) Then, the condenser lens 14b is formed at the position of each light receiving element 14a on the substrate. This state is shown in FIG. Specifically, a resin material is dropped onto the position of each light receiving element 14a on the substrate by a known ink jet head. Thereafter, the resin material dropped on the substrate is deformed by heat treatment to form a hemispherical condenser lens 14b.

  As another example of (4), a condensing lens 14b may be formed on each light receiving element 14a by photolithography. Specifically, first, a thermally deformable resin layer such as a photoresist is formed on the substrate. This heat-deformable resin layer is formed by a known means such as ink-jet droplets or spin coating. Next, the heat-deformable resin layer is patterned by photolithography to remove unnecessary portions, thereby forming a cylindrical preform. Then, the preform of the heat-deformable resin layer remaining at the corresponding position of each light receiving element 14a is deformed by heat treatment to form a hemispherical condenser lens 14b.

  Furthermore, as another example of the first step, the condenser lens 14b and the partition wall base 15a may be formed by any one of the following methods (A) to (C).

  (A) In this method, the columnar preform processed into the condenser lens 14b and the partition wall base 15a can be simultaneously formed with the same resin in the first step. In this case, the condenser lens 14b and the partition base 15a can be formed by a simpler process.

  First, for example, a resin is dropped at a predetermined position on the substrate under an inkjet droplet to form the preform and the partition base 15a. Or after forming a uniform resin layer on a board | substrate, patterning by photolithography may be performed and the preform and the partition base 15a may be formed. Thereafter, the preform at the corresponding position of each light receiving element 14a is deformed by heat treatment to form a hemispherical condenser lens 14b. In the case of (a), since the partition base 15a is also deformed at the stage of the heat treatment, it is necessary to set the shape and size of the partition base 15a in consideration of such deformation.

  (B) In the first step, the condenser lens 14b of the light receiving element 14a can be formed first, and then the partition wall base 15a can be formed. In this case, for example, a resin is dropped at a predetermined pitch by ink jet into a space where the partition base portion 15a is formed on the substrate and dried. Thereafter, the dropping position of the resin is shifted, and the above steps are repeated to form the partition wall base portion 15a on the substrate, which is then cured with ultraviolet rays. Alternatively, the partition base 15a can be formed by photolithography by applying a resist in a space where the partition base 15a is formed.

  In the method (b), since the condenser lens 14b is formed before the partition base 15a, the partition base 15a is not deformed by the heat treatment when forming the condenser lens 14b. Therefore, a material having low heat resistance can be used for the resin forming the partition wall base 15a, and it is not necessary to consider thermal deformation in the manufacturing process in designing the partition wall base 15a.

  (C) It is also possible to transfer the shape to the lower resin layer by etching after forming the resin layer double and processing the upper resin layer into the shape of the condenser lens and the partition wall base. it can.

  First, a transparent resin layer (such as silicon oxide or silicon nitride) and a heat-deformable resin layer (such as a phenol / novolak resist) are sequentially stacked on the upper surface of the substrate of the image sensor 14. Next, the upper heat-deformable resin layer is processed into the shape of the condensing lens 14b and the partition wall base portion 15a in the same manner as the steps (1) to (4) and (b) and (b). The transparent resin layer is formed by anisotropic etching such as reactive ion etching (RIE) using oxygen, preferably under the condition that the ratio of the etching rate between the transparent resin layer and the thermally deformable resin layer is 1: 1. Selective removal in the vertical direction. When such anisotropic etching in the vertical direction is performed, the upper heat-deformable resin layer is scraped and the shape of the heat-deformable resin layer is reflected in the transparent resin layer. The shapes of the condensing lens 14b and the partition wall base 15a are transferred respectively.

  According to the method (c), the condenser lens 14b and the partition wall base 15a can be formed of a resin material having no photosensitivity. Of course, the partition wall base 15a may be formed by the methods (1) to (3), and then only the condenser lens 14b may be formed by the method (c).

  Next, in the second step, the partition wall 15b is formed on the upper surface of the partition wall base 15a using the mold material 21 (see FIG. 5). Specifically, first, the mold member 21 having the cavity 21a corresponding to the shape of the partition wall 15b is placed in contact with the upper surface of the partition wall base portion 15a.

  Here, the thickness of the partition wall 15b is set smaller than the thickness of the upper surface of the partition wall base portion 15a. Therefore, in a state where the mold member 21 is in contact with the upper surface of the partition wall base portion 15a, the cavity 21a of the mold material 21 does not protrude from the upper surface of the partition wall base portion 15a. Therefore, when the resin is injected into the cavity 21a of the mold member 21, the resin can be prevented from leaking onto the light receiving element 14a. In addition, since the height of the upper surface of the partition wall base 15a is higher than the top of the condenser lens 14b, the mold material 21 and the condenser lens 14b are in contact with the mold material 21 in contact with the upper surface of the partition base 15a. There is no interference.

  Thereafter, a resin material in which a pigment-based pigment such as carbon black is dispersed is injected into the cavity 21a of the mold material 21, and the resin material is cured to form the partition wall 15b on the upper surface of the partition base portion 15a (FIG. 5B). reference). Here, the injection of the resin material into the mold material 21 is performed from a gate (corresponding to the rib-shaped portion 15 c) provided on the side of the mold material 21. Although not particularly limited, the resin material is preferably injected into the cavity 21a of the mold material 21 under vacuum.

  And after completion | finish of a 2nd process, the micro lens array 13 is attached to the image pick-up element 14 which has the partition structure 15, and the image detection unit 11 is completed. At this time, in order to suppress the incidence of stray light from the side surface, the upper surface of the partition wall 15b of the partition wall structure 15 and the microlens array 13 may be bonded and shielded. Alternatively, the rib-shaped portion 15c, which is a gate at the time of forming the partition wall 15b, and the microlens array 13 may be fixed with an adhesive.

  In the first embodiment, it is not necessary to touch the barrier structure 15 having light shielding properties when the barrier structure 15 is bonded to the substrate of the image sensor 14. Therefore, the risk of damaging the partition wall structure 15 is reduced.

(Description of Second Embodiment)
FIG. 6 is a partial cross-sectional view showing the image sensor 14 in the second embodiment. In the second embodiment, the photocurable resin 16 is applied to the layout space of the partition wall structure 15 on the substrate of the image sensor 14, and then the photocurable resin 16 is cured by exposure with laser light to partition the base of the partition wall. Form. And the photocurable resin 16 is apply | coated on this partition base, and it exposes with a laser beam after that and the photocurable resin 16 is hardened. Thereby, the photocurable resin 16 is laminated | stacked on a partition base. Then, the partitioning structure 15 is formed by stacking the layers of the photocurable resin 16 by repeating the application and curing cycle of the photocurable resin 16 a plurality of times. In the partition wall structure 15 of the second embodiment, the thickness of the partition wall and the partition wall base is set to be substantially constant.

  Also in the second embodiment, since the partition wall structure 15 having a light shielding property is formed in a state of being bonded to the substrate of the image sensor 14 in advance, substantially the same effect as that of the first embodiment can be obtained. In the light shielding structure of the second embodiment, since the wall surface becomes rough due to the lamination of the photocurable resin 16, a function of preventing unnecessary reflection of incident light can be expected.

(Description of the third embodiment)
FIG. 7 is a cross-sectional view showing a configuration of an image detection unit in the third embodiment. Moreover, FIG. 8 is explanatory drawing which shows the formation process of the partition structure 15 in 3rd Embodiment.

  In the third embodiment, the on-chip condensing lens 14b is omitted from each light receiving element 14a, and a light-transmitting transparent resin layer 17 is uniformly formed on the light receiving surface of the imaging element 14 to form the partition wall base 15a. Configure (see FIG. 8A). And the partition 15b is formed on said transparent resin layer 17 by the 2nd process of 1st Embodiment (refer FIG.8 (b)). Also in the third embodiment, substantially the same effect as in the first embodiment can be obtained.

(Supplementary items of the embodiment)
(1) In the above embodiment, the division shape of the small regions in the image detection unit 11 is not limited to a square lattice shape, and may be, for example, a honeycomb-like arrangement. Further, the light receiving elements 14a arranged in the imaging element 14 are not necessarily arranged in a square lattice shape. Furthermore, the arrangement interval of the microlens array 13 and the partition wall structure 15 may be different for each divided region.

  (2) In the above example, the portion between the light receiving element where the partition wall base on the light receiving surface is formed has a structure different from that of the light receiving element. However, the partition wall base can be formed on a part of the light receiving elements after the light receiving elements are continuously formed. In this case, the light receiving element having the partition wall base formed thereon does not function as an original light receiving element. However, according to such a configuration, there is an advantage that the relative alignment between the position where the partition wall base is formed and the substrate is relatively loose. In addition, since the original substrate is covered with a light receiving element and is the same as a general two-dimensional image sensor, it may be possible to share a manufacturing process or divert a general-purpose two-dimensional image sensor. There are also advantages.

  (3) In the case of the image detection unit 11 for focus detection, the image sensor 14 in which the light receiving elements 14a for two pixels are arranged in each small area may be used (so-called TCL same configuration). In the image detection unit 11 having the above configuration, focus detection can be performed by the second sampling method disclosed in Japanese Patent Application Laid-Open No. 2007-11314 by the same applicant.

  (4) Further, in the case of the image detection unit 11 for focus detection, an imaging element 14 in which lines of a plurality of light receiving elements 14a having different arrangement directions in each small region may be used.

  (5) In the first embodiment, the partition wall base 15a is formed by laminating the photocurable resin 16 in the same manner as in the second embodiment, and the thin partition wall 15b is formed on the upper surface using the mold material 21. Also good.

  (6) In the first embodiment, the example in which the thickness of the partition wall base portion 15a (the width in the direction parallel to the light receiving surface) is constant has been described (note that the partition wall structure 15 from the direction of the arrow in FIG. 3A). This state is shown in FIG. However, in the present invention, as shown in FIG. 9B, the partition wall base 15a may be thickened at the corner where the partition wall bases 15a intersect each other. In this case, when the mold material 21 is brought into contact with the upper surface of the partition wall base 15a in the second step, the mold material 21 can be easily supported by the improvement of the strength of the partition wall base 15a, thereby improving workability. Similarly, for the partition wall 15b of the partition wall structure 15, the corner portion where the partition wall 15b intersects may be thickened.

  (7) In the first embodiment, an example in which four rib-like portions 15c are linearly provided in the partition wall structure 15 is illustrated, but injection into a resin material into the mold material 21, attachment of the microlens array 13, etc. May be changed as appropriate. Further, the outer peripheral portion of the partition wall structure 15 may be thick to have a frame-like configuration.

  (8) In the above embodiment, the example in which the partition structure 15 is formed on the sensor chip (substrate) of each image sensor 14 has been described. However, the partition structure 15 is formed collectively on the wafer before the sensor chip is cut out. May be.

  The present invention can be implemented in various other forms without departing from the spirit or the main features thereof. For this reason, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The present invention is defined by the claims, and the present invention is not limited to the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

(A): perspective view showing the image detection unit of the first embodiment, (b): exploded perspective view of the image detection unit. Sectional view showing the configuration of the image detection unit (A): Cross-sectional view of the image sensor of the first embodiment, (b): Partial enlarged view of the broken line part of FIG. The figure explaining an example of the 1st process in a 1st embodiment. The figure explaining an example of the 2nd process in 1st Embodiment. Partial sectional view of the image sensor of the second embodiment Sectional drawing which shows the structure of the image detection unit in 3rd Embodiment. Explanatory drawing which shows the formation process of the partition structure in 3rd Embodiment (A): The figure which shows the state of the partition structure from the arrow direction of Fig.3 (a), (b): The figure which shows the modification of a partition base

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Image detection unit, 13 ... Micro lens array, 14 ... Imaging device, 14a ... Light receiving element, 14b ... Condensing lens, 15 ... Partition structure, 15a ... Partition base, 15b ... Partition, 16 ... Photocurable resin, 17 ... transparent resin layer, 21 ... mold material

Claims (11)

A plurality of light receiving elements arranged on the light receiving surface;
A partition base formed between the plurality of light receiving elements on the light receiving surface;
A light-shielding partition formed on the upper surface of the partition base;
An image pickup device comprising: The imaging device according to claim 1,
The imaging device according to claim 1, wherein a width of the partition wall in a direction parallel to the light receiving surface is smaller than a width of a top surface of the partition base portion in a direction parallel to the light receiving surface. The imaging device according to claim 1 or 2,
Each of the plurality of light receiving elements has a lens for focusing on the light receiving element,
An image pickup device, wherein an upper surface of the partition wall base is higher than a top of the lens. A first step of forming a partition wall base between the plurality of light receiving elements on the light receiving surface by attaching and curing a first resin on the light receiving surface of the imaging element in which the plurality of light receiving elements are arranged;
A second step of forming a partition wall standing on the partition wall base by attaching a second resin to the upper surface of the partition wall base and curing the second resin;
The manufacturing method of the partition structure of an image pick-up element characterized by the above-mentioned. In the manufacturing method of the partition structure of the image sensor according to claim 4,
The first resin and the second resin are different resins, and when each is in a cured state, the second resin has a light shielding property higher than that of the first resin. Method. In the manufacturing method of the partition structure of the image sensor according to claim 4 or 5,
An on-chip lens is arranged for each light receiving element on the light receiving surface of the image sensor,
The height of the upper surface of the said partition base is formed in the position higher than the top part of the said on-chip lens, The manufacturing method of the partition structure of the image pick-up element characterized by the above-mentioned. In the manufacturing method of the partition structure of an image sensor given in any 1 paragraph of Claims 4-6,
A method for manufacturing a partition structure of an image sensor, wherein the partition wall is formed to have a width smaller than a width of an upper surface of the partition base. In the manufacturing method of the partition structure of an image sensor given in any 1 paragraph of Claims 4-7,
In the second step, a mold material having a cavity corresponding to the partition wall is disposed in contact with the upper surface of the partition base, and the second resin is injected into the cavity to form the partition wall. The manufacturing method of the partition structure of an image pick-up element. In the manufacturing method of the partition structure of the image sensor according to claim 4,
A method of manufacturing a partition structure of an imaging element, wherein the second step is repeated a plurality of times, and the partition is laminated and formed on the partition base.   An image pickup device comprising a partition wall base and a partition wall formed by the manufacturing method according to claim 4. An image detection unit comprising the imaging device according to claim 1.

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