JP2004104259A - Solid-state imaging element and solid-state imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state imaging apparatus having a solid-state imaging element the imaging face of which is curved to be a cylindrical face in order to correct a lens aberration (curved image face) that attains the reliability of electric connection to its electrode pads. <P>SOLUTION: The solid-state imaging apparatus has the solid-state imaging element 2, at least the imaging face 3 of which is curved to be a cylindrical face, and a package 4 containing the solid-state imaging element 2. The electrode pads 5 of the solid-state imaging element 2 are arranged along an uncurved direction. The electrode pads 5 and the electrode pads 7 of the package 4 are electrically connected. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a solid-state imaging device and a solid-state imaging device including the solid-state imaging device.
[0002]
[Prior art]
2. Description of the Related Art Generally, a solid-state imaging device used in a solid-state imaging device is separated from a semiconductor wafer that has undergone several semiconductor manufacturing processes by dicing or the like into individual chips, that is, individual chips. The solid-state imaging device thus obtained is formed in a flat plate shape, has a thickness of about 300 μm, and has a rigid shape characteristic (a characteristic that is rigid and does not deform). The imaging surfaces formed on the main surfaces of the plurality of solid-state imaging devices are arranged along the main surfaces so as to have a planar state.
[0003]
On the other hand, in order to form an image of a subject on a solid-state imaging device (imaging surface), an imaging optical system is required. An imaging lens is incorporated in the imaging optical system, and an image of a subject is formed on the solid-state imaging device by the imaging lens.
[0004]
In general, when a subject is imaged by an imaging lens, a focal position shift occurs between a central portion and a peripheral portion of an imaging surface due to a lens aberration phenomenon called field curvature.
That is, as shown in FIG. 14, in a configuration in which an imaging optical system 33 including an imaging lens 32 and a diaphragm 31 is disposed on a solid-state imaging device 34, when focusing on the center of the imaging surface, In this case, a problem of focusing in the air occurs. As a result, the imaging characteristics are deteriorated, for example, the image quality becomes non-uniform between the central part and the peripheral part of the image.
[0005]
Lens aberrations are corrected by such means as combining a plurality of imaging lenses with respect to such a problem. However, this method of combining a plurality of imaging lenses imposes a heavy burden on the design of the imaging optical system including the imaging lenses, and the image quality is deteriorated due to insufficient correction of lens aberrations. Was feared.
[0006]
Therefore, Japanese Patent Application Laid-Open Nos. 2001-156278 and 2001-284564 have proposed methods of correcting a lens aberration generated in an imaging optical system by fixing a solid-state imaging device in a curved shape.
[0007]
8 to 10 show examples of the solid-state imaging device described in JP-A-2001-284564. In the solid-state imaging device 41 of FIG. 8, a curved support portion (convex portion) 43 is integrally formed on the upper surface of a holding member 42, and the solid-state imaging element 44 is held by the holding member 42 so that the imaging surface faces upward. Be composed. The solid-state imaging device 44 is held in a curved shape so that the solid-state imaging device 44 comes into contact with the upper surface of the holding member 42 and the curved support portion 43 due to its shape flexibility.
In the solid-state imaging device 45 of FIG. 9, a step-shaped concave portion 46 is integrally formed on the upper surface of the holding member 42, and the solid-state image sensor 44 is brought into contact with the concave bottom surface 46 a and the upper surface of the holding member 42 serving as a curved support portion. The solid-state imaging device 44 is thus held in a curved shape.
In the solid-state imaging device 47 of FIG. 10, a communication hole 49 is provided on the bottom surface of the concave portion (the stepped envelope is a curved surface) 48 of the holding member 42, and the solid-state imaging device 44 communicates with the solid-state imaging device 44 disposed on the holding member 42. By sucking air from the holes 49, the solid-state imaging device 44 is held in a curved shape.
[0008]
11 to 12 show examples of the solid-state imaging device described in JP-A-2001-156278. The solid-state imaging device 21 includes a package 23 having a required cylindrical bottom surface 22, and a curved solid-state imaging device 25 having an imaging surface 24 facing upward along the bottom surface 22 of the package 23. 23, a transparent glass cover 26 is arranged. The solid-state imaging device 25 has a rectangular shape when viewed from above, has a long side curved, and electrode pads 27 made of, for example, Al are arranged along the curved long side. The electrode pads 31 on the package 23 side are also arranged in the long side direction corresponding to the electrode pads 27 of the solid-state imaging device 25, and the corresponding electrode pads 27 and 31 are connected by wire bonding using, for example, Au fine wires 32. You. Although not shown, external leads that are electrically connected to the electrode pads 31 are led out of the package 23.
[0009]
[Problems to be solved by the invention]
By the way, the solid-state imaging device in which the solid-state imaging device curved in a cylindrical or spherical shape is fixed has the following problems.
[0010]
The solid-state imaging device is, for example, about 30 μm thick by mechanical polishing and chemical polishing, which are usually called BGR (Back Grinder), on the back surface of a semiconductor substrate (Si substrate) on which the imaging element is formed. The imaging surface is curved by being polished to have a small thickness. When the curved imaging surface is fixed to the package surface, distortion (undulation) is generated on the imaging surface, and a gap is also generated between the package surface and the back surface of the solid-state imaging device due to the distortion (undulation). For this reason, the ultrasonic waves are diffused during the wire bonding by the ultrasonic pressure bonding method, and bonding non-adhesion occurs. In addition, the above-mentioned gap causes peeling or cracking of the electrode pad due to the ultrasonic impact during wire bonding. When the impact of the ultrasonic wave is large, it may develop into a crack of the image sensor.
[0011]
On the other hand, in the wire bonding of an Au thin wire to the electrode pad of a normal flat solid-state imaging device, since the height position of each electrode pad is constant, the bonding strength (shear strength) is substantially uniform. . However, when the wire bonding of the curved solid-state imaging device to the electrode pad is performed using a normal wire bonding apparatus, the inclination angle θ of the electrode pad 27 (see FIG. 15) gradually changes, so that the inclination angle is particularly large. It has been found that the shear strength between the outer electrode pad 27 and the Au fine wire 32 where θ increases becomes lower than the allowable value, and the connection becomes insufficient. In addition, since the height position of each electrode pad changes, it is difficult to recognize the position of the electrode pad, and it is difficult to perform stable wire bonding.
[0012]
The present invention has been made in view of the above points, and has enabled a solid-state imaging device having a solid-state imaging surface curved in a cylindrical shape to perform stable electrical connection to an electrode pad, thereby stabilizing quality and improving yield. An image pickup device and a solid-state image pickup device provided with the image pickup device are provided.
[0013]
[Means for Solving the Problems]
The solid-state imaging device according to the present invention has a configuration in which at least the imaging surface is curved in a cylindrical shape and the electrode pads are arranged along a direction in which the electrode pads are not curved. As a solid-state imaging device, the entire imaging chip having an imaging surface can be curved into a cylindrical surface.
[0014]
In the solid-state imaging device of the present invention, by arranging the electrode pads of the solid-state imaging device in a horizontal direction that is not curved, the height position and the inclination angle of each electrode pad are the same, and the solid-state imaging device is stable with respect to each electrode pad. Electrical connection is made possible.
[0015]
The solid-state imaging device according to the present invention includes a configuration in which at least the imaging surface is curved in a cylindrical shape, and includes a solid-state imaging element arranged along a direction in which the electrode pads are not curved, and an electrical connection is made to the electrode pads. I do.
[0016]
In the solid-state imaging device of the present invention, since the electrode pads of the solid-state imaging device are arranged along the direction in which the electrode pads are not curved, the height position and the inclination angle of each electrode pad become the same, and the solid-state imaging device is stable with respect to each electrode pad. Electrical connection becomes possible. Therefore, it is possible to improve the quality and yield of this type of solid-state imaging device.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0018]
1 to 3 show one embodiment of a solid-state imaging device according to the present invention. The solid-state imaging device 1 according to the present embodiment includes a solid-state imaging device 2 having an imaging surface 3 and at least the imaging surface 3 curved in a cylindrical shape, and a package 4 containing the solid-state imaging device 2. . The solid-state imaging device 2 of the present embodiment is configured by curving the entire rectangular imaging chip into a cylindrical shape along the long side direction. The solid-state imaging device 2 is curved into a cylindrical surface having a required curvature so as to correct lens aberration (field curvature) generated in the imaging optical system. In particular, a plurality of electrode pads 5 made of, for example, Al are curved. Are arranged along a direction that is not performed, that is, a short side direction. The electrode pads 5 are arranged on both sides of the imaging surface 3.
[0019]
The curved solid-state imaging device 2 has, for example, a thin, flexible surface, for example, 100 μm or less, preferably 50 μm or less, more preferably 20 μm or less, by a chemical mechanical polishing method (BGR method) or the like. It can be formed in a cylindrical shape so that the height difference Δh between the end and the center of the imaging surface 3 is about 100 μm.
[0020]
As the solid-state imaging device 2, for example, a CCD imaging device, a CMOS imaging device, and the like can be applied.
[0021]
The package 4 is made of, for example, a ceramic material, and the entire bottom surface 4a on which the solid-state imaging device 2 is arranged is formed in a cylindrical shape having the same curvature as the solid-state imaging device 2. Steps 6 [6A, 6B] are formed on one of two opposite inner side walls in the package 4, and the upper surfaces of the steps 6A, 6B are electrically connected to the electrode pads 5 of the solid-state imaging device 2, respectively. For example, an electrode pad 7 made of Al is formed. Although not shown, external leads electrically connected to the electrode pads 7 are led out of the package 4.
[0022]
The solid-state imaging device 2 is arranged in the package 4 so that the back surface thereof is in contact with the bottom surface 4a, and the electrode pad 5 of the imaging device 2 and the electrode of the package 4 are wire-bonded with a thin metal wire, for example, an Au thin wire 8. The pads 7 are electrically connected. Then, the upper part of the package 4 is sealed with a transparent cover member, for example, a flat cover glass 9.
[0023]
According to the present embodiment, the layout of the electrode pads 5 of the solid-state imaging device 2 that is curved into a cylindrical surface is arranged in a direction that is not curved, in this example, in a short side direction, so that the height of each electrode pad 5 is increased. The position and the inclination angle are the same without changing, and the wire bonding can be easily and stably performed on each electrode pad 5 under the same conditions. As shown in FIG. 2, the electrode pad 5 is also inclined. However, if dedicated bonding conditions are set for the electrode pad 5 which is inclined under a certain condition, a stable and higher share strength can be ensured, and good. Wire bonding is possible. Since the height position of each electrode pad 5 is the same, it is easy to recognize the position of the electrode pad during bonding. Therefore, the conventional inexpensive wire bonding technology can be used, and the cost can be reduced as a solid-state imaging device, and stable quality can be secured.
[0024]
Note that, besides using a conventional wire bonding apparatus, a dedicated wire bonding apparatus in which bonding conditions are set for electrode pads inclined at a constant angle can also be used. For example, it is also possible to use a dedicated wire bonding apparatus in which the inclined electrode pad is viewed horizontally and the capillary is vertically applied to the electrode pad.
[0025]
In the present embodiment, it is possible to prevent a decrease in yield due to an imaging chip destruction or the like caused by an impact at the time of connection by wire bonding, as compared with a case where the electrode pads are laid out in the conventional bending direction. That is, the electrode pads 5 are laid out on the short side that is not curved, and wire bonding is performed on the short side firmly in contact with the bottom surface 4a of the package 4, so that the imaging chip is not broken by an impact during wire bonding. Therefore, the yield of this type of solid-state imaging device having a curved solid-state imaging device can be improved.
[0026]
4 and 5 show another embodiment of the solid-state imaging device according to the present invention. In the solid-state imaging device 11 according to the present embodiment, the region having the imaging surface 3 with respect to the rectangular imaging chip is curved into a cylindrical shape along the long side direction, and both side regions 13 [ 13A, 13B] are formed in a flat plate shape, and the solid-state imaging device 12 is configured by arranging the electrode pads 5 on the regions 13A, 13B along a direction not curved. The package 4 is formed in a shape having a curved portion 14 and flat portions 15 [15A, 15B] on both sides thereof so that the bottom surface 4a corresponds to the shape of the solid-state imaging device 12, and the step portions 6A, 6B. The electrode pads 7 are arranged on the upper surface of the substrate. Other configurations are the same as those in FIGS. 1 to 3 described above, and thus redundant description will be omitted.
[0027]
According to the solid-state imaging device 11 of the present embodiment, the imaging surface 3 of the solid-state imaging element 12 is curved, and lens aberration (field curvature) can be corrected. The region is formed as a flat portion 15 [15A, 15B], and the electrode pad 5 is formed along the short side direction that is not curved in the flat portion 15, so that the height position, the inclination angle (= 0) of each electrode pad 5 °) is the same, and stable and favorable wire bonding can be performed as in the above-described embodiment. In the wire bonding to the electrode pad 5, since the electrode pad 5 is flat, the tip ball portion of the Au fine wire 8 guided by the capillary is crushed evenly vertically, and the impact given to the imaging chip is dispersed by 1 / area. Thus, it is possible to more reliably prevent the imaging chip from cracking.
Therefore, also in this embodiment, the conventional inexpensive wire bonding technology can be used, stable quality can be ensured, and the yield can be improved.
[0028]
FIG. 7 shows another embodiment of the solid-state imaging device according to the present invention. The solid-state imaging device 17 according to the present embodiment includes the solid-state imaging device 2 in which the entire imaging chip similar to FIGS. 1 to 3 is curved, and the electrode pad 7 of the package 4 is connected to the electrode pad 5 of the solid-state imaging device 2. It is formed with the same inclination angle θ. Other configurations are the same as those in FIGS. 1 to 3 described above, and thus redundant description will be omitted.
[0029]
According to the solid-state imaging device 17 of the present embodiment, since the height position and the inclination angle of each electrode pad 5 of the curved solid-state imaging device 2 are the same, each of the electrode pads 5 is the same as described with reference to FIGS. Wire bonding can be stably performed on the electrode pad 5 under the same conditions. On the other hand, since the electrode pads 7 of the package 4 are also inclined at the same angle θ, for example, when using a dedicated wire bonding apparatus that vertically touches the inclined electrode pads, the electrode pads 5 of the solid-state imaging device 2 and the electrodes of the package 4 are used. Wire bonding can be performed on the pad 7 under the same conditions. In addition, the same operation and effect as those of the solid-state imaging device 1 of FIGS.
[0030]
In the solid-state imaging device according to the present invention, the connection between the solid-state imaging device and the package 4 is performed by wire bonding. However, the external connection to the electrode pad of the solid-state imaging device is not limited to wire bonding. A method such as bonding) connection or bump connection may be used. In this case, the package 4 may be omitted, and the solid-state imaging device may be attached to a required support member directly as an external connection or directly via a TAB connection. External connection to each electrode pad of the solid-state imaging device at this time can also be performed uniformly and stably.
[0031]
According to the present invention, an imaging camera can be configured by including the above-described solid-state imaging device and an imaging optical system. According to this imaging camera, since the imaging surface of the solid-state imaging device is curved, lens aberration (field curvature) can be corrected without imposing a burden on the design of the imaging optical system. In addition, since the electrical connection of the solid-state imaging device to each electrode pad can be easily and stably performed, stable quality can be ensured and the yield can be improved.
[0032]
【The invention's effect】
According to the solid-state imaging device according to the present invention, by arranging the electrode pad layout of the solid-state imaging device curved in a cylindrical shape along the direction in which the solid-state imaging device does not bend, wire bonding to each electrode pad, TAB connection, bump connection, etc. External connection can be stably performed. Therefore, chip destruction and the like can be prevented, and the quality of the solid-state imaging device can be stabilized and the yield can be improved.
[0033]
According to the solid-state imaging device of the present invention, by providing the solid-state imaging device in which the electrode pads are laid out in a direction that does not bend, the quality of this type of solid-state imaging device that enables correction of lens aberration (field curvature) is provided. Can be stabilized and the yield can be improved. In addition, lens aberration (field curvature) can be corrected, and the design of an imaging optical system when an imaging camera is applied is facilitated.
[Brief description of the drawings]
FIG. 1 is a plan view illustrating an embodiment of a solid-state imaging device according to the present invention.
FIG. 2 is a cross-sectional view taken along line AA of FIG.
FIG. 3 is a sectional view taken on line BB of FIG. 1;
FIG. 4 is a plan view showing another embodiment of the solid-state imaging device according to the present invention.
FIG. 5 is a cross-sectional view taken along line CC of FIG. 4;
FIG. 6 is a sectional view taken along line DD in FIG.
FIG. 7 is a cross-sectional view of a main part showing still another embodiment of the solid-state imaging device according to the present invention.
FIG. 8 is a configuration diagram illustrating an example of a conventional solid-state imaging device.
FIG. 9 is a configuration diagram illustrating another example of a conventional solid-state imaging device.
FIG. 10 is a configuration diagram illustrating another example of a conventional solid-state imaging device.
FIG. 11 is a plan view showing still another example of the conventional solid-state imaging device.
FIG. 12 is a sectional view taken along line EE in FIG. 11;
FIG. 13 is a sectional view taken on line FF of FIG. 11;
FIG. 14 is an explanatory diagram for describing lens aberration (image surface distortion).
FIG. 15 is an explanatory diagram for describing an inclination angle of an electrode pad.
[Explanation of symbols]
1, 11, 17, 21, 41, 45, 47 ··· solid-state imaging device, 2, 12, 25, 34, 44 · · · solid-state imaging device, 3, 24 · · · imaging surface, 4, 23 · · · package, 8 , 32 ... Au fine wire, 5, 7, 27, 31 ... electrode pad, 26 ... transparent glass cover, 31 ... stop, 32 ... imaging lens, 33 ... imaging optical system, 42 ... holding Member, 49 ... communicating hole

Claims (9)

At least the imaging surface is curved into a cylindrical shape,
A solid-state imaging device, wherein electrode pads are arranged along a direction that is not curved. 2. The solid-state imaging device according to claim 1, wherein the entire imaging chip having an imaging surface is curved in a cylindrical shape. A solid-state imaging device having at least an imaging surface curved into a cylindrical surface,
A package containing the solid-state imaging device,
The solid-state imaging device according to claim 1, wherein the electrode pads of the solid-state imaging device are arranged along a direction in which the electrode pads are not bent, and the electrode pads and the package-side electrode pads are electrically connected. The solid-state imaging device according to claim 3, wherein the entire imaging chip constituting the solid-state imaging device is curved in a cylindrical shape. The solid-state imaging device according to claim 3, wherein the electrode pad on the solid-state imaging device side and the electrode pad on the package side are connected by wire bonding. At least the imaging surface is curved into a cylindrical shape, having a solid-state imaging device arranged along a direction in which the electrode pads are not curved,
A solid-state imaging device, wherein the electrode pads are externally connected by TAB bonding. 7. The solid-state imaging device according to claim 6, wherein the solid-state imaging device has an entire imaging chip having an imaging surface curved into a cylindrical surface. At least the imaging surface is curved into a cylindrical shape, having a solid-state imaging device arranged along a direction in which the electrode pads are not curved,
A solid-state imaging device, wherein the electrode pads are externally connected by bump bonding. 7. The solid-state imaging device according to claim 6, wherein the solid-state imaging device has an entire imaging chip having an imaging surface curved into a cylindrical surface.

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