JP5965984B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus, and more particularly to an imaging apparatus manufactured by a wafer level chip size package method.

  Electronic endoscopes equipped with an imaging device having a solid-state imaging device such as a CCD or a CMOS, a mobile phone with a camera, a digital camera, and the like are widely used. The imaging device includes an imaging element substrate portion on which a solid-state imaging element is formed, and a cover glass portion that protects the solid-state imaging element.

  In order to downsize and mass-produce an imaging device, a manufacturing method of an imaging device using a wafer level chip size package (W-CSP) method is known. For example, Japanese Patent Application Laid-Open No. 2003-204053 discloses a method in which a semiconductor wafer on which a large number of imaging elements are formed and a glass substrate or the like are joined and cut into pieces to obtain a large number of imaging devices in a lump. It is disclosed.

  Japanese Patent Application Laid-Open No. 2002-45333 discloses a horizontal imaging apparatus that captures a subject in a direction orthogonal to the imaging element surface. In the horizontal image pickup apparatus, a process of joining a right-angle prism to the upper surface of the cover glass is necessary.

  In other words, a known horizontal imaging apparatus requires a step of joining prisms to individual imaging apparatuses that are manufactured in one piece by the W-CSP method and separated into individual pieces. It was. In addition, in an imaging apparatus based on the W-CSP method, a cover glass is indispensable for protecting the imaging element. However, the dimension of the imaging device in the height direction (direction perpendicular to the imaging element surface) is increased by the thickness of the cover glass. For this reason, when the horizontal imaging apparatus manufactured by the W-CSP method is mounted on the endoscope distal end, the endoscope distal end may be enlarged.

JP 2003-204053 A JP 2002-45333 A

  An object of this invention is to provide a small-sized imaging device.

  An image pickup apparatus according to an embodiment of the present invention includes an image pickup element substrate unit having an image pickup element on a first main surface and having a back electrode connected to the image pickup element on a second main surface via a wiring unit; A right angle prism having a vertical surface perpendicular to the first main surface and an inclined surface inclined at 45 degrees, wherein the vertical surface is an incident surface and the inclined surface is a reflective surface; An image pickup apparatus including an adhesive layer that bonds the image pickup element substrate unit, wherein the outer dimensions of the image pickup element substrate unit and the right-angle prism are the same.

  An imaging device according to another embodiment of the present invention includes a plurality of imaging elements on a first main surface, and a plurality of imaging elements connected to the respective imaging elements on a second main surface via respective wiring portions. An imaging element substrate manufacturing step of manufacturing an imaging element substrate having a back electrode; a bonding substrate manufacturing step of bonding a transparent substrate to the first main surface of the imaging element substrate to manufacture a bonding substrate; A prism manufacturing step of manufacturing an optical path conversion element by forming a groove portion including a vertical surface perpendicular to the first main surface and an inclined surface on the transparent substrate; And an individualization step for separating the image pickup device.

  According to the present invention, a small imaging device can be provided.

1 is an external view of an imaging apparatus according to a first embodiment. It is an exploded view of the imaging device of a 1st embodiment. It is explanatory drawing for demonstrating the joint substrate preparation process of the imaging device of 1st Embodiment. It is an external view for demonstrating the joining board | substrate of the imaging device of 1st Embodiment. It is a perspective view for demonstrating the prism preparation process of the imaging device of 1st Embodiment. It is a cross-section figure for demonstrating the prism preparation process of the imaging device of 1st Embodiment. It is a perspective view for demonstrating the prism preparation process of the imaging device of 1st Embodiment. It is a perspective view for demonstrating the individualization process of the imaging device of 1st Embodiment. It is a cross-section figure for demonstrating the imaging device of 2nd Embodiment. It is a cross-section figure for demonstrating the endoscope which has the imaging device of 3rd Embodiment.

<First Embodiment>
Hereinafter, an imaging device 1 according to a first embodiment of the present invention and a method for manufacturing the imaging device 1 will be described with reference to the drawings. First, the structure of the imaging device 1 of the present embodiment will be described. As shown in FIGS. 1 and 2, the imaging device 1 includes an imaging element substrate unit 10, an adhesive layer 20, and a cover glass unit 30 that is a transparent substrate unit. The image pickup apparatus 1 is a horizontal type. In FIG. 1, a light beam incident on the vertical surface 32 of the cover glass unit 30 from the left side of the drawing is reflected by the inclined surface 31 and reaches the image pickup device 13 through the lower surface 33.

  As will be described later, the imaging device 1 is manufactured by a wafer level chip size package method. That is, after a large number of image pickup devices are manufactured in a batch on a wafer, they are separated into individual chips (image pickup devices) by cutting (dicing) processing. For this reason, as shown in FIG. 1, the outer dimensions of the image pickup device substrate section 10, the adhesive layer 20, and the cover glass section 30 are the outer dimensions of the image pickup apparatus 1, L1 and L2. Become. In other words, the outer dimensions (planar dimension) when viewed from above the image pickup device substrate section 10, the adhesive layer 20, and the cover glass section 30 are the same. In the imaging device 1, the imaging element substrate unit 10 and the cover glass unit 30 have side surfaces with the same inclination angle θ1, and therefore the outer dimensions in the L1 direction are slightly different. However, since the difference is slight, it can be considered that the outer dimensions of the imaging element substrate unit 10 and the cover glass unit 30 are the same.

  The image pickup device substrate section 10 has an image pickup element 13 on the first main surface 11, and has a back electrode 17 connected to the image pickup element 13 on the second main surface 12 through a through wiring 16 that is a wiring portion. . The through wiring 16 is connected to the imaging device 13 via the front surface electrode 15 and a surface wiring (not shown). On the upper surface of the image sensor 13, microlenses 14 corresponding to the number of pixels are formed.

  The cover glass part 30 has a protective member function for protecting the image sensor 13. Further, in the imaging device 1, the cover glass unit 30 includes a vertical surface 32 that is perpendicular to the first main surface 11 of the imaging element substrate unit 10 and an inclined surface 31 that is inclined 45 degrees. Moreover, it also has an optical path conversion element function. That is, in FIG. 1, θ1 = 45 degrees and θ2 = 90 degrees, and the cover glass portion 30 constitutes a right-angle prism. The inclined surface 31 is a reflecting surface of a right-angle prism. As described above, the light incident from the vertical surface 32 is reflected by the inclined surface 31, and the optical path direction is changed by 90 degrees to enter the imaging element 13.

  Further, the adhesive layer 20 that bonds the cover glass part 30 to the image pickup element substrate part 10 is configured to form an air gap 22 on the image pickup element formation region of the image pickup element substrate part 10. That is, an air gap 22 is formed between the imaging element forming region of the imaging element substrate unit 10 and the cover glass unit 30 by the frame-shaped adhesive layer 20. In other words, the adhesive layer 20 is not formed in the imaging element formation region.

  Since the imaging device 1 is manufactured by the W-CSP method, a cover glass portion that protects the imaging element 13 is indispensable. As already described, in a known horizontal imaging apparatus, it is necessary to further dispose a right-angle prism on the cover glass portion. However, in the imaging device 1, since the cover glass part 30 has a function as a right-angle prism, it is small and has high productivity.

  The imaging apparatus 1 having the air gap 22 has a high light collection effect of the microlenses 14 formed on the imaging element 13.

Next, the manufacturing method of the imaging device 1 will be described with reference to FIGS.
<Image sensor substrate manufacturing process>
An image pickup device substrate having a plurality of image pickup devices 13 on the first main surface 11 and having a plurality of back surface electrodes 17 connected to the respective image pickup devices 13 on the second main surface 12 through the respective through wirings 16. 10W is produced.

  The imaging element substrate 10W is made of, for example, a single crystal silicon substrate, and a plurality of imaging elements 13 are formed on the first main surface 11 using a semiconductor circuit manufacturing technique. As the image sensor, a CCD or CMOS is preferably used, but a separately manufactured image sensor chip may be disposed on the image sensor substrate 10W. Each imaging element 13 is formed with microlenses having the number of pixels using, for example, a transparent resin.

  A front surface electrode 15 connected to a front surface wiring (not shown) for power supply or signal transmission of the image sensor 13 is formed on the first main surface 11 of the image sensor substrate 10W. Yes. And the through-hole which reaches | attains the back surface of the front surface electrode 15 is formed by the dry etching process or the wet etching process from the 2nd main surface 12 side of the image pick-up element board | substrate 10W. That is, the through hole penetrates the single crystal silicon substrate, but its bottom is formed as a via hole that is the front electrode 15.

By forming a conductor such as copper or aluminum inside and at the bottom of the through hole, the through wiring 16 that is electrically connected to the front electrode 15 is formed. Further, a back electrode 17 connected to the through wiring 16 is formed on the second main surface 12. The back electrode 17 is an external connection electrode for mounting, and is formed using a convex copper bump or a solder ball.
Note that a side wiring may be used in place of the through wiring 16 as a wiring portion that connects the imaging element 13 on the first main surface 11 and the back electrode 17 on the second main surface 12.

  In FIG. 3, an example is shown in which the image sensor 13 is arranged in a 6 × 6 grid pattern on the image sensor substrate 10W. However, in actuality, the image sensor 13 is arranged in a grid pattern of 10 × 10 or more. Preferably, they are arranged in a lattice shape of 20 × 20 or more.

<Junction board manufacturing process>
As shown in FIGS. 3 and 4, a glass substrate 30 </ b> W that is a transparent substrate is bonded to the first main surface 11 of the imaging element substrate 10 </ b> W via an adhesive layer 20 </ b> W, and the bonded substrate 1 </ b> W is manufactured. An antireflection film may be formed on the lower surface 33 of the glass substrate 30W.

The adhesive layer 20 </ b> W is formed by applying an adhesive by patterning using a screen printing method or an inkjet method. That is, no adhesive is applied to the image sensor formation region of the first main surface 11 of the image sensor substrate 10W. The adhesive applied to the image sensor peripheral region other than the image sensor formation region is cured after the lower surface 33 of the glass substrate 30W is bonded. As the adhesive, an ultraviolet curable resin or a thermosetting resin can be used.
Note that when the bonding substrate manufacturing process is performed in a vacuum, air does not exist in the air gap 22 which is a sealed space, but for convenience, it is referred to as an air gap.

<Prism manufacturing process (separation process)>
As shown in FIG. 5 and FIG. 6, the first main part is obtained by dicing with a blade 2 having a 45-degree inclined surface (θ1 = 45 degrees) formed on one side from the upper surface 34 of the glass substrate 30 </ b> W on the image sensor. A groove portion 3 is formed which includes a vertical surface 32 perpendicular to the surface 11 and an inclined surface 31 inclined. That is, the surface of the blade 2 on which the slope is not formed is held at an angle of 90 degrees with respect to the first main surface 11 during the dicing process. By forming the groove portion 3 with the blade 2, an inclined surface 31 serving as a reflecting surface of the prism and a vertical surface 32 serving as a light incident surface of the prism are simultaneously formed.
In FIG. 5, a blade having straight teeth is shown for the sake of illustration, but of course, a widely used circular blade may be used.

  As shown in FIG. 7, in the manufacturing method of the imaging device 1 according to the present embodiment, in the prism manufacturing process, the bonding substrate 1W is divided into the rod-shaped substrate 1V composed of a plurality of imaging devices at the same time as the prism manufacturing. Is done. That is, the bottom of the groove 3 reaches the second main surface 12 of the image sensor substrate 10W.

<Polishing process>
After the prism manufacturing process, the inclined surface 31 serving as the reflecting surface of the prism of the bonded substrate 1W and the vertical surface 32 serving as the incident surface are polished. This is because it is difficult to ensure flatness and surface roughness that are acceptable for the imaging optical system only by dicing with the blade 2. The polishing process is performed until a flat surface satisfying the optical specifications is obtained by a method using a polishing liquid or the like similar to normal prism polishing. The polishing process is performed with reference to the second main surface 12 on which the back electrode 17 of the imaging device 1 is formed, and the angle and distance (plate thickness) between the first main surface 11 and the second main surface 12 are set. It is managed with high accuracy.

  The polishing process may be performed in units of individual imaging devices after the singulation process described later, but is preferably performed in the state of the rod-shaped substrate 1V in which the imaging devices 1 are arranged in a row as shown in FIG. The polishing process with the rod-shaped substrate 1V is not only efficient in terms of time and high in productivity, but also increases the processing accuracy of the prisms of the plurality of imaging devices, since the processing of the plurality of imaging devices for one row is performed collectively. It can be managed uniformly.

<Individualization process>
As shown in FIG. 8, in the singulation process, individual imaging devices 1 are singulated from the rod-shaped substrate 1V.

  According to the manufacturing method of this embodiment, the small imaging device 1 can be manufactured efficiently. That is, the manufacturing method of this embodiment has high productivity.

<Second Embodiment>
Next, the imaging device 1A and the manufacturing method of the imaging device 1A according to the second embodiment of the present invention will be described. Since the imaging device 1A and the manufacturing method of the imaging device 1A of the present embodiment are similar to the imaging device 1 and the manufacturing method of the imaging device 1 of the first embodiment, the same components are denoted by the same reference numerals and described. Is omitted.

  As shown in FIG. 9, the adhesive layer 20A of the imaging device 1A does not form an air gap. This is because the image sensor does not have a microlens. For this reason, the adhesive layer 20A is easier to manufacture than the adhesive layer 20 that requires patterning.

Further, the imaging apparatus 1 </ b> A has a reflective film 35 made of a metal thin film on the inclined surface 31. The reflection film 35 improves the reflection efficiency on the reflection surface of the prism. By providing the reflecting film 35 on the reflecting surface of the prism, observation with a bright image can be performed. As the reflective film 35, a highly reflective metal film such as aluminum or silver is formed by vapor deposition or sputtering. Further, it is preferable to form a protective film made of SiO ₂ or the like for preventing oxidation of the metal film on the outside of the reflective film 35. From the viewpoint of productivity, the reflective film 35 and the protective film are preferably formed in the state of the rod-shaped substrate 1V.

  The inclined surface 31 having the reflective film 35 has improved light reflection efficiency. That is, since the imaging apparatus 1A has less reflection loss on the inclined surface 31, the light from the imaging optical system is efficiently imaged on the imaging element 13.

  In the imaging apparatus 1A, the rod-like substrate 1V is manufactured by the step cut method. That is, in the prism manufacturing process, the blade 2 forms a groove only in the glass substrate 30W. That is, the bottom of the groove does not reach the image sensor substrate. For this reason, after the prism manufacturing process, the bonded substrate 1W is not separated into the rod-shaped substrate 1V, and is in a wafer state in which the groove 3 is formed. Then, after the prism manufacturing step, the rod-shaped substrate 1V is separated by a dicing process in the separation step. Note that the side surface of the image sensor substrate portion 10 </ b> A is perpendicular to the first main surface 11.

  In addition, a V-shaped groove having two reflecting surfaces is first formed by using blades having an inclination of 45 degrees on both sides, and then the bottom of the V-shaped groove and the separating portion of the two rod-shaped substrates are separated on a vertical surface. It may be.

  As shown in FIG. 9, in the imaging apparatus 1 </ b> A, similarly to the imaging apparatus 1, the chip size L <b> 1 is set to be substantially the same as the prism height H <b> 1, that is, the thickness of the cover glass portion 30. That is, the imaging devices 1 and 1A do not dispose a prism on the cover glass part 30, but process the cover glass part 30 to produce a prism. Is possible.

  As shown in FIG. 1 and the like, in the imaging devices 1 and 1A, a part of the upper surface of the glass substrate 30W is not processed into the inclined surface 31 in the prism manufacturing process. That is, the prisms of the imaging devices 1 and 1A have the upper surface 34. This is to facilitate handling of the rod-shaped substrate 1V and the imaging devices 1 and 1A. For example, in the imaging device 1 having the upper surface 34, the lower surface 33, that is, the upper surface 34 parallel to the first main surface 11 can be used as a reference when mounting on the wiring board. In addition, the imaging device 1 having the above structure is less likely to cause chipping or the like as compared with a case where the glass end surface has an acute angle.

<Third Embodiment>
Next, an endoscope 40 having the imaging device 1A will be described as a third embodiment. FIG. 10 is a view for explaining a cross-sectional structure of the distal end portion of the insertion portion of the endoscope 40. As shown in FIG. 10, in the endoscope 40 in which the imaging device 1 </ b> A is incorporated at the distal end portion of the insertion portion, the imaging optical system 43 including a plurality of lens portions 41 and the imaging device 1 </ b> A are fixed by a frame portion 46. Yes. The inside of the frame portion 46 is filled with a non-conductive resin filler having a high thermal conductivity. A cable 45 is connected to the wiring board 44 on which the imaging device 1 </ b> A is mounted via the back electrode 17.

  An imaging optical system 43 is aligned (optically aligned) and fixed in front of the cover glass portion 30 constituting the prism of the imaging device 1. For this reason, the optical image from the imaging optical system 43 is optically changed by 90 degrees on the inclined surface 31 and formed on the pixel area of the imaging element 13.

  The endoscope 40 having the imaging device 1A and the like at the distal end portion of the insertion portion can be reduced in diameter and less invasive because the cover glass portion 30 indispensable as a protective member is a right-angle prism having an optical path conversion function. is there. Further, the endoscope 40 is low in cost because of its high productivity.

  The present invention is not limited to the above-described embodiment, and various changes and modifications can be made without departing from the scope of the present invention. For example, the reflective film described in the second embodiment may be used for the imaging device 1 of the first embodiment, or the imaging device 1 of the first embodiment may be mounted on the endoscope of the third embodiment. .

DESCRIPTION OF SYMBOLS 1, 1A ... Imaging device, 1V ... Rod-shaped board | substrate, 1W ... Bonding board, 2 ... Blade, 3 ... Groove part, 10 ... Imaging element board | substrate part, 10W ... Imaging element board | substrate, 11 ... 1st main surface, 12 ... 2nd 13 ... imaging device, 14 ... micro lens, 15 ... front surface electrode, 16 ... through wiring, 17 ... back electrode, 20, 20A, 20W ... adhesive layer, 21 ... adhesive layer, 22 ... air gap 30 ... Cover glass part, 30W ... Glass substrate, 31 ... Inclined surface, 32 ... Vertical surface, 34 ... Upper surface, 35 ... Reflective film, 40 ... Endoscope, 41 ... Lens part, 43 ... Imaging optical system, 44 ... Wiring board, 45 ... cable, 46 ... frame, O ... optical axis

Claims (4)

An image pickup device substrate portion having an image pickup device on a first main surface and having a back electrode connected to the image pickup device on a second main surface via a wiring portion;
A right angle prism having a vertical surface perpendicular to the first main surface and an inclined surface inclined by 45 degrees, wherein the vertical surface is an incident surface and the inclined surface is a reflecting surface;
An imaging device comprising: an adhesive layer that bonds the imaging element substrate unit and the right-angle prism,
An imaging apparatus characterized in that the imaging element substrate section and the right-angle prism have the same outer dimensions. An image pickup device substrate portion having an image pickup device on a first main surface and having a back electrode connected to the image pickup device on a second main surface via a wiring portion;
A transparent substrate portion having a vertical surface perpendicular to the first main surface and an inclined surface inclined by 45 degrees, wherein the vertical surface is an incident surface and the inclined surface is a reflective surface;
An imaging device comprising: an adhesive layer that bonds the imaging element substrate portion and the transparent substrate portion;
Side of said entrance surface and the imaging element substrate portion in contact with the transparent substrate portion, Ri same plane near to the entrance surface,
The imaging apparatus , wherein the inclined surface of the transparent substrate portion and the side surface of the imaging element substrate portion in contact with the inclined surface have the same inclination angle .   An image pickup device substrate portion having an image pickup device on a first main surface and having a back electrode connected to the image pickup device on a second main surface via a wiring portion;
  A transparent substrate portion having a vertical surface perpendicular to the first main surface and an inclined surface inclined by 45 degrees, wherein the vertical surface is an incident surface and the inclined surface is a reflective surface;
  An imaging device comprising: an adhesive layer that bonds the imaging element substrate portion and the transparent substrate portion;
  A side surface of the imaging element substrate portion in contact with the incident surface of the transparent substrate portion is in the same plane as the incident surface;
  An image pickup apparatus, wherein a side surface of the image pickup element substrate portion in contact with the inclined surface of the transparent substrate portion is perpendicular to the first main surface. The imaging apparatus according to claim 1, further comprising a reflective film on the inclined surface.

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