JP2009111130A - Imaging apparatus and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the manufacturing cost of an imaging apparatus for which a back surface irradiation type solid-state imaging element is sealed. <P>SOLUTION: In the solid-state imaging element 11, a back surface 11b on the opposite side of a front surface 11a where an electrode pad 15 is formed is a light receiving surface. A first fixing member 16 is formed on the back surface (light receiving surface) 11b. A transparent support substrate 12 is in the same plane size as the solid-state imaging element 11 and is fixed to the side of the back surface 11b by the first fixing member 16. A package base body 13 has a lead terminal 18, and an opening 13a is formed at a position where the light receiving surface of the solid-state imaging element 11 faces. A second fixing member 17 is formed around the opening 13a so as to fix the peripheral edge part of the transparent support substrate 12 to the periphery of the opening 13a of the package base body 13. A wire 19 is connected between the electrode pad 15 and the lead terminal 18. A sealing resin 14 covers the entire surface 11a of the solid-state imaging element 11 and the wire 19. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an imaging device formed by sealing (packaging) a back-illuminated solid-state imaging device and a manufacturing method thereof.

  In an electronic camera such as a digital camera, a CCD (Charge Coupled Device) type or CMOS (Complementary Metal Oxide Semiconductor) type solid-state imaging device made of a semiconductor chip is used as an imaging device. These electronic cameras are required to be miniaturized as well as to have high functions. In connection with this, in the solid-state imaging device, the number of pixels is increased and the size of the pixel is reduced. However, if the size of the pixel is simply reduced, the amount of incident light (sensitivity) to the light receiving element in the pixel decreases. Thus, increasing the aperture ratio of each pixel (ratio of the incident light amount to the light receiving element with respect to the incident light amount to the pixel) is a problem.

  Normally, a solid-state imaging device is configured to receive light incident from the surface side of a semiconductor substrate on which an electrode or the like is formed by a light receiving element formed in the semiconductor substrate, and the incident light is blocked by the electrode or the like. This is a factor that hinders improvement of the aperture ratio (that is, high sensitivity). Therefore, in recent years, back-illuminated solid-state imaging devices have been proposed in order to increase the sensitivity along with the miniaturization of pixels (for example, see Patent Documents 1 and 2). The back-illuminated solid-state imaging device is configured to receive light incident from the back side where no electrode is formed, and can maximize the aperture ratio.

The above-described back-illuminated solid-state imaging device needs to be thinned to a thickness of about 10 μm so that light can be incident from the back side of the semiconductor substrate to the internal light receiving device, and the mechanical strength is insufficient. There is a problem that it causes troubles during dicing and mounting. For this reason, in patent document 1, the intensity | strength is ensured by thinning other parts, leaving the peripheral part (pad formation part) of a solid-state image sensor. In Patent Document 2, the strength is ensured by bonding a support substrate made of a silicon substrate or the like to the surface (non-light-receiving surface) side where the electrodes of the solid-state imaging device are formed.
Japanese Patent Laid-Open No. 9-82852 JP 2006-32561 A

  However, as in the imaging device described in Patent Document 1, it is difficult to thin the other portions while leaving the peripheral portion of the solid-state imaging device, so that the manufacturing is not easy because the normal polishing method is difficult. It will increase the cost. Further, when the support substrate is bonded to the surface side of the solid-state image sensor as in the imaging device described in Patent Document 2, it is necessary to form a through electrode in the support substrate so that the electrode terminal is exposed to the outside. Therefore, the manufacturing is complicated and the manufacturing cost is increased. As described above, the conventional imaging device in which the back-illuminated solid-state imaging device is sealed has a common problem that it is not easy to manufacture and causes an increase in manufacturing cost.

  The present invention has been made in view of the above problems, and provides an imaging apparatus that includes a back-illuminated solid-state imaging device, is easy to manufacture, and can reduce manufacturing costs, and a manufacturing method thereof. For the purpose.

  In order to achieve the above object, an imaging apparatus according to the present invention includes a back-illuminated solid-state imaging device having a light-receiving surface opposite to the surface on which the electrode pad is formed, and light reception by the solid-state imaging device. A first supporting member formed on a surface, a transparent support substrate having the same planar size as the solid-state imaging device, and fixed to the light-receiving surface side of the solid-state imaging device by the first fixing member; A package base having a terminal and having an opening formed at a position where the light-receiving surface of the solid-state imaging element faces; and a peripheral edge of the transparent support substrate fixed to the periphery of the opening of the package base. A second fixing member formed around the opening, a wire connected between the electrode pad and the lead terminal of the solid-state image sensor, the entire surface of the solid-state image sensor and the wire. Coated seal Characterized by comprising a resin.

  The first fixing member is preferably made of a thermosetting adhesive. Moreover, it is preferable that the said 2nd fixing member consists of an adhesive sheet which has adhesiveness on both surfaces. Moreover, it is preferable that the said adhesive sheet is black and has light-shielding property.

  The package base has an open container shape with one end open and a recess for accommodating the solid-state imaging device and the transparent support substrate, and the opening is formed on a surface on the other end side of the package base. It is preferable that the sealing resin is filled in the recess.

  Further, the manufacturing method of the imaging device of the present invention is a solid-state imaging device in which a plurality of back-illuminated solid-state imaging devices each having a light-receiving surface opposite to the surface on which the electrode pads are formed are arranged in a matrix. A step of manufacturing a wafer; a step of polishing and thinning the back side of the solid-state image sensor wafer; a step of forming a color filter on the back surface of the solid-state image sensor wafer; and a step of forming a color filter on the color filter. A step of forming one fixing member, a step of fixing a transparent support substrate to the back surface side of the solid-state imaging element wafer via the first fixing member, and the solid-state imaging elements arranged in a matrix And a step of cutting the solid-state image sensor wafer and the transparent support substrate, and a package having lead terminals and having openings formed at positions where the light-receiving surfaces of the solid-state image sensor face each other. Preparing a second base member and forming a second fixing member around the opening; and surrounding the opening of the package base with the peripheral portion of the transparent support substrate through the second fixing member. A step of fixing the electrode pad of the solid-state imaging device and the lead terminal by a wire, and injecting a sealing resin so as to cover the entire surface of the solid-state imaging device and the wire And a step of curing the sealing resin.

  The image pickup apparatus of the present invention has a structure in which a transparent support substrate having the same planar size as the solid-state image pickup device is fixed to the back surface (light-receiving surface) side of the back-illuminated solid-state image pickup device. It is easy to manufacture because it can be manufactured by dicing and mounting a solid-state image sensor wafer on which a plurality of solid-state image sensors are formed supported by a transparent support substrate and ensuring mechanical strength. The manufacturing cost can be reduced. In addition, a transparent support substrate is pasted on the back side of the solid-state imaging device, and it is not necessary to form a through electrode on the support substrate.

  1 and 2, an imaging apparatus 10 according to the present invention includes a back-illuminated solid-state imaging device 11, a transparent support substrate 12 holding the solid-state imaging device 11, and an opening 13a at a position where the solid-state imaging device 11 faces. The package base 13 is formed and the transparent support substrate 12 is fixed so as to cover the opening 13a, the sealing resin 14 that seals the solid-state imaging device 11, and the like. The package base 13 has an open container shape with one end opened, and the opening 13a is formed on the other end. The package base 13 is formed of a material having insulating properties and light shielding properties such as ceramic and resin.

  The solid-state imaging device 11 is a back-illuminated two-dimensional image sensor made of a rectangular flat semiconductor chip and having a back surface 11b opposite to the front surface 11a on which the electrode pads 15 are formed as a light receiving surface. The electrode pad 15 is an external electrode for inputting / outputting a signal to / from an external drive circuit (not shown) or a signal processing circuit (not shown). A plurality are arranged along the side. Since the solid-state imaging device 11 is a backside illumination type, the backside 11b side is polished and thinned, and the thickness is about 10 μm.

  The transparent support substrate 12 is made of a rectangular flat glass substrate having the same planar size as that of the solid-state image sensor 11, and is thicker than the solid-state image sensor 11 and about 500 μm. The solid-state imaging device 11 has a back surface 11 b fixed to the lower surface of the transparent support substrate 12 via a first fixing member 16. The transparent support substrate 12 has a slightly larger planar size than the opening 13 a, and a peripheral edge thereof is fixed around the opening 13 a of the package base 13 via the second fixing member 17.

  The first fixing member 16 is preferably a thermosetting adhesive with good heat resistance. The second fixing member 17 is preferably an adhesive sheet that has adhesiveness on both sides and is black and has a light shielding property. By using an adhesive sheet as the second fixing member 17, not only the package base 13 and the transparent support substrate 12 are fixed, but also dust (movable foreign matter) generated on the surface of the transparent support substrate 12 due to the adhesive property. A side effect such as capturing is obtained.

  The package base 13 has an open container shape as described above, and is formed with a recess 13b that accommodates the solid-state imaging device 11 and the transparent support substrate 12. The package base 13 is formed with a plurality of lead terminals 18 having one end 18a exposed in the recess 13b and the other end 18b exposed outside. One end (inner lead portion) 18 a of each lead terminal 18 and the electrode pad 15 of the solid-state imaging device 11 are connected by a conductive wire 19.

  The recess 13 b of the package base 13 is filled with a sealing resin 14 having a light shielding property, and the sealing resin 14 covers the entire surface 11 a of the solid-state imaging device 11 and the wire 19. The sealing resin 14 serves to prevent deformation of the wire 19, reinforce the fixing strength of the solid-state imaging device 11 and the transparent support substrate 12, and prevent moisture from entering the first fixing member 16. The sealing resin 14 is not particularly limited in terms of viscosity, and may be any of an ultraviolet curable type, a thermosetting type, and a normal temperature curable type.

  The imaging device 10 configured as described above is used in a state where the other end (outer lead portion) 18b of the lead terminal 18 is mounted on a circuit board or the like (not shown). The solid-state imaging device 11 receives light through the transparent support substrate 12 bonded to the back surface 11b side that is a light receiving surface, and generates an imaging signal by photoelectric conversion. An imaging signal generated by the solid-state imaging device 11 is output from the lead terminal 18 through the wire 19 to the outside.

  In FIG. 3, the cross-sectional structure of the light receiving portion of the solid-state imaging device 11 will be described. The light receiving element 20 is a buried photodiode formed in the semiconductor substrate 21 and receives light incident from the back surface 11b side. The light receiving elements 20 are two-dimensionally arranged in the semiconductor substrate 21 with a pitch of several μm. The semiconductor substrate 21 is thinned to a thickness of about 10 μm so that light can be incident from the back surface 11b side, and a color filter 22 that splits incident light is provided on the back surface 11b side.

  The light receiving element 20 receives incident light and generates a signal charge corresponding to the amount of light. On the surface 11 a side of the semiconductor substrate 21, the signal charge accumulated in the light receiving element 20 is transferred to a charge transfer path (when the solid-state image sensor 11 is a CCD type) and an amplifier (when the solid-state image sensor 11 is a CMOS type). A gate electrode 23 is provided for this purpose. The gate electrode 23 is made of polysilicon or the like, and its periphery is covered with an interlayer insulating layer 24 made of silicon oxide or the like. The surface of the interlayer insulating layer 24 is planarized. A wiring layer 25 made of aluminum or the like connected to the gate electrode 23 through a contact plug (not shown) is formed on the interlayer insulating layer 24. The wiring layer 25 is made of silicon oxide or the like. A protective insulating layer 26 is formed. The wiring layer 25 is connected to the above-described electrode pad 15 provided on the surface 11a side.

  In the back-illuminated solid-state imaging element 11, a structure such as a gate electrode does not exist on the incident side of the light receiving element, so that a high aperture ratio can be obtained. For this reason, sufficient light receiving sensitivity can be obtained without providing a microlens on the color filter 22. The first fixing member 16 is formed on the color filter 22, and the transparent support substrate 12 is fixed through the first fixing member 16.

  The transparent support substrate 12 supports the thinned solid-state image sensor 11 to increase the mechanical strength, and protects the back surface (light receiving surface) 11b of the solid-state image sensor 11. In addition, since the transparent support substrate 12 has the same planar size as the solid-state imaging device 11 and the minimum necessary size, the material cost as a cover member can be minimized.

  Further, since the transparent support substrate 12 is attached to the back surface (light receiving surface) 11b side of the solid-state imaging device wafer 30, the electrode pad 15 is exposed to the front surface 11a side and penetrates the support substrate as in the conventional case. It is not necessary to form an electrode, and manufacturing is easy.

  Next, the manufacturing method of the imaging device 10 will be described along the flowchart shown in FIG. First, as shown in FIG. 5, by using a known semiconductor wafer process technique, a solid-state image sensor wafer 30 in which a plurality of the above-mentioned solid-state image sensors 11 (structures other than the color filter 22) are arranged in a matrix on a silicon wafer is obtained. Manufacture (step S1). At this stage, the solid-state imaging device wafer 30 is not thinned and has a thickness of about 725 μm.

  Next, the back surface 11b side of the solid-state imaging device wafer 30 is uniformly polished by a method such as back grinding, and thinned to a thickness of about 10 μm so that light can be incident from the back surface 11b side (step S2). . Next, the color filter 22 is formed on the back surface 11b (step S3). The color filter 22 is formed by a normal method by applying, exposing, and developing a color photoresist material.

  Next, the transparent support substrate 12 made of a glass substrate having the same size as the solid-state imaging device wafer 30 is prepared, and the first fixing member 16 is formed on the surface by applying an adhesive (step S4). Next, the solid-state imaging device wafer 30 is attached to the first fixing member 16 so that the back surface 11b side on which the color filter 22 is provided is opposed to the first fixing member 16, and as shown in FIG. Then, the solid-state imaging device wafer 30 and the transparent support substrate 12 are fixed to each other (step S5).

  Next, as shown in FIG. 6B, using a dicer (not shown) having a diamond blade or the like, the solid-state image sensor wafer 30 and the transparent support substrate 12 are cut, and each solid-state image sensor 11 is replaced with a transparent support substrate. 12 is divided into pieces while being supported at 12 (step S6). Next, a package base 13 having an open container shape in which one end is opened and a recess 13b is formed and an opening 13a is formed on a surface opposite to the open end (the bottom surface of the recess 13b) is prepared. A second fixing member 17 made of an adhesive sheet is formed on the peripheral edge of the portion 13a on the concave portion 13b side (step S7), and the transparent supporting substrate 12 is attached to the second fixing member 17 as shown in FIG. The transparent support substrate 12 is fixed to the package base 13 so as to cover the opening 13a by contacting the peripheral edge of the substrate (step S8).

  Next, as shown in FIG. 7B, the inner lead portion 18a of the lead terminal 18 provided on the package base 13 and the electrode pad 15 of the solid-state imaging device 11 are connected by the wire 19 by wire bonding technology (step 19). S9). Then, as shown in FIG. 7C, the sealing resin 14 is injected into the recess 13b so as to cover the entire surface 11a of the solid-state imaging device 11 and the wire 19, and the sealing resin 14 is cured (step S10). ). The imaging device 10 is completed through the above steps.

  In the above manufacturing method, since the thin solid-state imaging device wafer 30 is cut and separated in a state of being attached to the transparent support substrate 12, mechanical strength is ensured and stable manufacturing can be performed.

1 is an external perspective view illustrating a configuration of an imaging apparatus according to an embodiment of the present invention. It is a schematic sectional drawing in alignment with the AA of FIG. It is a schematic sectional drawing which shows the structure of the light-receiving part of a solid-state image sensor. 3 is a flowchart illustrating a method for manufacturing an imaging apparatus according to an embodiment of the present invention. It is an external appearance perspective view which shows a solid-state image sensor wafer and a transparent support substrate. (A) is a schematic cross-sectional view showing a state in which a transparent support substrate is attached to the back surface of the thinned solid-state image sensor wafer, and (B) is a schematic cross-sectional view showing a state in which the solid-state image sensor is singulated. . (A) is a schematic cross-sectional view showing a state in which a solid-state imaging device is fixed to a package substrate, (B) is a schematic cross-sectional view showing a state where wire bonding is performed, and (C) is filled with a sealing resin. It is a schematic sectional drawing which shows the state.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Imaging device 11 Solid-state image sensor 11a Front surface 11b Back surface (light-receiving surface)
DESCRIPTION OF SYMBOLS 12 Transparent support substrate 13 Package base body 13a Opening part 13b Recessed part 14 Sealing resin 15 Electrode pad 16 1st adhering member 17 2nd adhering member 18 Lead terminal 19 Wire 20 Light receiving element 21 Semiconductor substrate 22 Color filter 30 Solid-state image sensor wafer

Claims (6)

A back-illuminated solid-state imaging device in which the back surface opposite to the surface on which the electrode pad is formed is a light-receiving surface;
A first fixing member formed on the light receiving surface of the solid-state imaging device;
A transparent support substrate having the same planar size as that of the solid-state image sensor and fixed to the light-receiving surface side of the solid-state image sensor by the first fixing member;
A package base having a lead terminal and having an opening formed at a position facing the light-receiving surface of the solid-state imaging device;
A second fixing member formed around the opening so as to fix the peripheral edge of the transparent support substrate around the opening of the package base;
A wire connected between the electrode pad of the solid-state imaging device and the lead terminal;
A sealing resin covering the entire surface of the solid-state imaging device and the wire;
An imaging apparatus comprising:   The imaging apparatus according to claim 1, wherein the first fixing member is made of a thermosetting adhesive.   The imaging apparatus according to claim 1, wherein the second fixing member is made of an adhesive sheet having adhesiveness on both sides.   The imaging apparatus according to claim 3, wherein the adhesive sheet is black and has a light shielding property.   The package base has an open container shape in which one end is opened and a recess for accommodating the solid-state imaging device and the transparent support substrate is formed, and the opening is provided on a surface on the other end side of the package base. The imaging apparatus according to claim 1, wherein the sealing resin is filled in the recess. Manufacturing a solid-state image sensor wafer in which a plurality of back-illuminated solid-state image sensors having a light-receiving surface opposite to the front surface on which the electrode pads are formed are arranged in a matrix;
Polishing and thinning the back side of the solid-state imaging device wafer;
Forming a color filter on the back surface of the solid-state imaging device wafer;
Forming a first fixing member on the color filter;
Fixing a transparent support substrate to the back surface side of the solid-state imaging device wafer via the first fixing member;
Cutting the solid-state imaging device wafer and the transparent support substrate so as to divide each of the solid-state imaging devices arranged in a matrix;
Preparing a package base having a lead terminal and having an opening formed at a position where the light-receiving surface of the solid-state imaging element faces, and forming a second fixing member around the opening;
Fixing the periphery of the transparent support substrate to the periphery of the opening of the package base via the second fixing member;
Connecting the electrode pad of the solid-state imaging device and the lead terminal by a wire;
Injecting a sealing resin so as to cover the entire surface of the solid-state imaging device and the wire, and curing the sealing resin;
A method for manufacturing an imaging apparatus, comprising:

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