1. Field of the Invention
The present invention relates to an image pickup apparatus that includes an image pickup chip in which an optical member is bonded on a light-receiving portion, a method for manufacturing the image pickup apparatus, and an endoscope system that includes the image pickup apparatus.
2. Description of the Related Art
An image pickup apparatus including an image pickup chip is, for example, arranged at a distal end portion of an electronic endoscope and used. An important task with regard to electronic endoscopes is to reduce a diameter of the distal end portion thereof, and consequently there is a demand to miniaturize the image pickup apparatus.
First, for comparison purposes, a wafer-level-packaging-type image pickup apparatus will be briefly described. A wafer-level-packaging-type image pickup apparatus is manufactured by cutting into individual pieces a bonded wafer in which an image pickup wafer that includes a plurality of image pickup chips and a glass wafer are bonded. Therefore, an entire area of a first main surface on which a light-receiving portion of an image pickup chip is formed is covered by a cover glass. It is necessary to form an electrode pad for sending and receiving signals to and from the light-receiving portion on a second main surface (rear surface) via through-wiring. However, a through-wiring formation process is a complex process that includes through-hole formation, insulating layer formation, and conductor layer formation and the like.
Japanese Patent Application Laid-Open Publication No. 2008-118568 discloses an image pickup apparatus in which a light-receiving portion and an electrode pad are arranged on a first main surface. Unlike a wafer-level-packaging-type image pickup apparatus, it is not necessary to form through-wiring in the aforementioned image pickup apparatus, and it is thus easy to produce the image pickup apparatus.
In a case where positioning accuracy is inadequate, there is a problem that if a side face of the cover glass is too near the light-receiving portion, an optical flare will be generated as the result of light that is incident from an image pickup optical system being reflected by the side face of the cover glass to form reflected light that thereafter arrives at the light-receiving portion.
Therefore, while it is also conceivable to bond a cover glass that has a plan-view dimension that is significantly larger than the image pickup chip taking into account the fact that the positioning accuracy is low, in such a case there will be a problem that an external diameter of the image pickup apparatus will increase.
An image pickup apparatus according to an embodiment of the present invention includes: a rectangular parallelepiped image pickup chip made of a semiconducting material and in which a plurality of function portion patterns including a light-receiving portion are formed on a first main surface; and an optical member in which an alignment mark is formed at each of at least two places that are in a predetermined positional relationship with a function portion pattern, and which is made of a transparent material that is bonded via an adhesive layer so as to cover the light-receiving portion.
A method for manufacturing an image pickup apparatus according to another embodiment of the present invention includes: a process of fabricating an image pickup chip wafer made of a semiconducting material in which a plurality of image pickup chip patterns made of a plurality of function portion patterns that each include a light-receiving portion are formed on a first main surface; a process of fabricating a plurality of rectangular parallelepiped image pickup chips by cutting the image pickup chip wafer into individual pieces; a process of forming, on an optical member wafer, a plurality of alignment mark sets, in each of which alignment marks are respectively formed at positions that are in a predetermined positional relationship with at least two places of the function portion pattern of the image pickup chip pattern; a process of fabricating a plurality of optical members that are rectangular in a planar view and on each of which one of the alignment marks set is formed, by cutting the optical member wafer into individual pieces; and a process of bonding the image pickup chip and the optical member via an adhesive layer while aligning an alignment mark of the optical member and the function portion pattern that is in a predetermined positional relationship with the alignment mark.
An endoscope system according to another embodiment of the present invention includes: an endoscope including a rectangular parallelepiped image pickup chip made of a semiconducting material and in which a plurality of function portion patterns including a light-receiving portion are formed on a first main surface, and an optical member in which an alignment mark is formed at each of at least two places that are in a predetermined positional relationship with a function portion pattern and which is made of a transparent material that is bonded via an adhesive layer so as to cover the light-receiving portion, wherein: the alignment mark in plurality that are formed by a metal layer are formed on a bonding surface of the optical member, the optical member is a cover glass, a filter, a prism or a member having a lens function, and an image pickup apparatus in which the optical member is bonded so that the alignment mark covers a corner portion of the light-receiving portion is arranged at a distal end portion of an insertion portion; and a processor comprising a processing portion that processes a rectangular endoscopic image that is picked up by the image pickup apparatus, masks a corner portion of the endoscopic image, and outputs an endoscopic image that does not display the corner portion.
As shown in
The rectangular parallelepiped image pickup chip 10 is an image pickup device such as a CMOS image sensor made of a semiconducting material such as silicon, in which a light-receiving portion 11 is formed on a first main surface 10SA. An electrode pattern (hereunder, also referred to as a “electrode pad”) 12 that is connected by wiring (not shown) for sending and receiving signals to and from the light-receiving portion 11 is also arranged on the first main surface 10SA. A plurality of the electrode pads 12 to which the signal wires 40 are bonded, respectively, are provided in a row along an edge of the image pickup chip 10. Hereunder, a pattern that is formed on the first main surface 10SA for an image pickup function is referred to as a function portion pattern. That is, in the image pickup chip 10, the light-receiving portion 11, the wiring and the electrode pattern 12 are function portion patterns.
The cover glass 30 is positioned so as to cover the light-receiving portion 11 and not cover an electrode group 12S that includes a plurality of the electrode pads 12, and is bonded to the image pickup chip 10.
With regard to outer dimensions (plan-view dimensions) of the image pickup chip 10, each side thereof is an extremely small size of a number of millimeters, for example, 1 mm. Consequently, as described above, it is not easy to align the image pickup chip 10 and the cover glass 30.
However, in the image pickup apparatus 1, on a bonding surface (second main surface) 30SB of the cover glass 30, alignment marks 31A and 31B (alignment mark set 31S) are respectively formed at two places that are in a predetermined positional relationship with the light-receiving portion 11 that is a function portion pattern of the image pickup chip 10. Hereunder, the alignment marks 31A and 31B are each referred to as alignment mark 31.
Therefore, alignment of the image pickup chip 10 and the cover glass 30 in the image pickup apparatus 1 can be performed accurately and easily. Consequently, manufacture of the image pickup apparatus 1 is easy.
For example, while accuracy when alignment is performed using an outer peripheral portion of the image pickup chip 10 and an outer peripheral portion of the cover glass 30 is around ±20 μm, accuracy in the case of performing alignment using the light-receiving portion 11 and the alignment mark set 31S is ±3 μm or less.
In a case where positioning accuracy is inadequate, there is a problem that if a side face of the cover glass is too near the light-receiving portion, an optical flare will be generated as the result of light that is incident from an image pickup optical system being reflected by the side face of the cover glass to form reflected light that thereafter arrives at the light-receiving portion.
Therefore, while it is also conceivable to bond a cover glass that has a plan-view dimension that is significantly larger than the image pickup chip taking into account the fact that the positioning accuracy is low, in such a case there will be a problem that an external diameter of the image pickup apparatus will increase.
Since the positioning accuracy is high in the structure of the image pickup apparatus 1, there is no risk of reflected light arriving at the light-receiving portion and generating an optical flare due to a side face of the cover glass being too close to the light-receiving portion.
In addition, in the image pickup apparatus 1, the light-receiving portion 11 that is a function portion pattern is used for alignment. Therefore, since it is not necessary to form a mark (alignment mark) that is used only for the purpose of alignment on the image pickup chip 10, miniaturization of the image pickup apparatus 1 is facilitated.
Next, a method for manufacturing the image pickup apparatus 1 will be described with reference to the flowchart in
As shown in
As shown in
As shown in
That is, as shown in
The alignment marks 31 are formed of a material that is used for fabrication of the image pickup wafer 10W, such as a metal, silicon nitride, silicon oxide or resin, that is, the alignment marks 31 are formed of a material used in semiconductor manufacturing, and there is no risk of deterioration of the image pickup chip 10 due to contamination.
In particular, it is preferable that the alignment marks 31 be made of a metal such as Cr, Ti or Cu, since it is easy for an image photographed by an alignment apparatus to be foamed with a high degree of contrast.
The alignment marks 31, for example, are fabricated by depositing Ti/Cr on one face of a glass wafer made of transparent glass, and thereafter patterning with a photoresist, and then etching.
As shown in
As described above, on each cover glass 30, the alignment marks 31A and 31B (alignment mark set 31S) are respectively formed at two places that are in a predetermined positional relationship with a function portion pattern of the image pickup chip 10.
In this connection, naturally an order in which the image pickup chip fabrication process and the cover glass fabrication process are performed may be reverse to that described above. Further, as shown in
An image that is photographed by an alignment apparatus is processed to perform pattern recognition, and alignment of the image pickup chip 10 and the cover glass 30 is performed. That is, by photographing an image of the first main surface 10SA of the image pickup chip 10 and an image of the second main surface 30SB of the cover glass 30 and performing pattern recognition, the corner portion 11X of the light-receiving portion 11 of the image pickup chip 10 and the center 31X of the alignment mark 31 of the cover glass 30 are recognized, and a relative position between the image pickup chip 10 and the cover glass 30 moves to a position at which the corner portion 11X and the center 31X match.
Note that, to prevent a decrease in the alignment accuracy due to a thickness of the cover glass 30, the alignment marks 31 are formed on the second main surface 30SB that is the bonding surface of the cover glass 30.
In addition, in the image pickup apparatus that includes the image pickup optical system 50 on the cover glass 30 (see
When the image pickup chip 10 and the cover glass 30 are in an aligned state, the image pickup chip 10 and the cover glass 30 are bonded while being pressed together via the adhesive layer 20.
The adhesive layer is selected from among ultraviolet-curing resins or thermosetting resins in consideration of transparency and moisture resistance and the like. The adhesive layer may be a liquid resin or may be a film resin. If the adhesive layer is a film resin, the adhesive layer may be fixed on the cover glass 30 in advance.
In addition, the signal wire 40 is bonded to the electrode pad 12 that is not covered by the cover glass 30.
As described above, according to the method of the present embodiment it is possible to easily manufacture the image pickup apparatus 1 in which the light-receiving portion 11 and the electrode pad 12 are arranged on the first main surface 10SA of the image pickup chip 10, and the light-receiving portion 11 is covered by the cover glass 30.
Further, since the alignment accuracy between the image pickup chip 10 and the cover glass 30 is high, a small cover glass 30 can be used, and thus the image pickup apparatus 1 has a small size.
For example, in a case where the alignment accuracy is 2 μm, in the image pickup apparatus 1, a height of a plan-view dimension thereof is (10Y) or less, and the height will be the same as that of the plan-view dimension of the image pickup chip 10. Further, a width of a plan-view dimension of the image pickup apparatus 1 is also the same as that of the plan-view dimension of the image pickup chip 10.
Next, image pickup apparatuses according to modifications of the first embodiment, and methods for manufacturing the image pickup apparatuses according to the modifications will be described. Since the image pickup apparatuses according to the modifications and the like are similar to the image pickup apparatus 1 of the embodiment, the same constituent elements are assigned the same reference numerals, and a description thereof is omitted.
In manufacturing the image pickup apparatus of the present invention, alignment is performed by processing an image photographed by an alignment apparatus and performing pattern recognition. Therefore, as in the case of the image pickup apparatus 1, it is not necessary for the positions to be overlapping at the time of aligning a part of the alignment mark 31 and a part of the light-receiving portion 11, and it is sufficient that the two components are in a predetermined positional relationship.
Consequently, each of image pickup apparatuses 1A to 1G of the following Modifications 1 to 7 also has the advantageous effects of the image pickup apparatus 1.
In an image pickup apparatus 1A of Modification 1 that is shown in
For example, highly accurate alignment is enabled by previously inputting the predetermined relational position information (distance d, relative angle θ) into the alignment apparatus.
In an image pickup apparatus 1B of Modification 2 that is shown in
That is, the alignment marks 31 may be in a predetermined positional relationship with any of the function portion patterns of the image pickup chip 10.
Further, a cover glass 30B is set so as to be arranged within the surface the image pickup chip 10, and plan-view dimensions of the image pickup apparatus 1A are the same as the plan-view dimensions of the image pickup chip 10.
For example, in a case where the alignment accuracy is ±2 μm, a height of the cover glass 30B is (10Y—2 μm) or less, and a width is also designed in consideration of the alignment accuracy.
In an image pickup apparatus 1C of Modification 3 that is illustrated in
The guard ring 15 is a functional pattern that is made of a material having moisture resistance, in particular a material with low moisture permeability such as a metal, and has a function for preventing the infiltration of moisture to the light-receiving portion 11 via the adhesive layer 20.
In this connection, in the image pickup apparatus 1C, a height 30Y of the cover glass 30C is greater than the height 10Y of the image pickup chip 10, and one part of the cover glass 30C also protrudes from a side face of the image pickup chip 10. That is, the dimensions of the cover glass can be set in accordance with the specifications of the image pickup apparatus.
In an image pickup apparatus 1D according to Modification 4 that is illustrated in a cross-sectional schematic diagram in
A cavity portion (cavity) 20X is formed in the upper side of the light-receiving portion 11 in the image pickup apparatus 1D. To make this kind of shape, for example, the alignment marks 31 that are cavities and the cavity portion 20X in the upper side of the light-receiving portion 11 may be formed by patterning a film-like resin 31D on the surface of the cover glass 30, and the image pickup apparatus 1D may be fabricated so that the remaining resin 31D that is not removed forms the adhesive layer 20D, or the image pickup chip 10 and the cover glass 30 may be bonded via the adhesive layer 20D using an adhesive after forming the cavity portion 20X by using a separate member as a spacer.
The light-receiving portion 11 of the image pickup apparatus 1D is also covered by a transparent insulating layer of a multilayer wiring layer 12D for connecting the light-receiving portion 11 and the electrode pad 12, and a color filter 21Y and a microlens 21Z are further arranged thereon. If the adhesive layer 20D is arranged on the microlens 21Z, a lens function will be lost.
In the image pickup apparatus 1D in which a part of the adhesive layer 20D is the cavity portion 20X, the microlens function will not be lost.
In an image pickup apparatus 1E of Modification 5 that is illustrated in
In addition, in the cover glass 30E, the alignment marks 31 are respectively formed at four places that are in a predetermined relationship with four corner portions of the light-receiving portion 11, respectively. To achieve highly accurate alignment, it is preferable to form the alignment marks 31 at least at two places, and the alignment marks 31 may be formed at three or more places. In a case where the alignment marks 31 are formed at three or more places, alignment may be performed using two places, and the alignment accuracy may be calculated and corrected using another alignment mark 31.
Note that, as long as an optical member made of a transparent material that covers the light-receiving portion 11 can cover the light-receiving portion 11 and the alignment marks 31 can be formed, the shape thereof may be of a filter such as an infrared cut-off filter or a low-pass filter, a prism, or a member having a lens function or the like.
An image pickup apparatus 1F of Modification 6 that is shown in
As already described above, in the image pickup apparatus 1F that includes the image pickup optical system 50 on the cover glass 30, since the second main surface 30SB is a position at which the image height of the image pickup optical system 50 becomes a maximum, the adverse effects caused by reflection and scattering of light by the alignment marks 31 are small.
In an image pickup apparatus 1G according to Modification 7 that is shown in
The light shielding pattern 30P is a so-called optical mask, and because the alignment marks 31G that are formed utilizing a part thereof can be fabricated simultaneously with formation of the light shielding pattern 30P, it is not necessary to add a new process.
As shown in
If the alignment marks 31 of the cover glass 30 are bonded so as to cover corner portions of the light-receiving portion 11, as in the configuration of the image pickup apparatus 1 and the like, as shown in
In the endoscope system 9, because a signal-processing portion 3A of the processor 3 masks the corner portions of an image pickup image by means of an electronic image mask 61, as shown in
The endoscope system 9 includes the small-size image pickup apparatus 1 that is easy to manufacture and the like, and furthermore, the unwanted images 31Q of the alignment marks 31 are not displayed in the endoscopic image 60.
Number | Date | Country | Kind |
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2013-108138 | May 2013 | JP | national |
This application is a continuation application of PCT/JP2014/059258 filed on Mar. 28, 2014 and claims benefit of Japanese Application No. 2013-108138 filed in Japan on May 22, 2013, the entire contents of which are incorporated herein by this reference.
Number | Date | Country | |
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Parent | PCT/JP2014/059258 | Mar 2014 | US |
Child | 14945911 | US |