Patent Application
20120007148
1. Technical Field
The present invention relates to a solid-state image pickup device, and more particularly, a solid-state image pickup device for realizing a small and thin solid-state image pickup device.
2. Description of Related Art
An image pickup device produced by so-called face-down mounting has been proposed. In the face-down mounting, bumps made of metal such as Au are formed on connection terminals of a solid-state image pickup element separated from a glass substrate, and the bumps are connected to predetermined terminals on the glass substrate (see, for example, JP-A-6-204442 and JP-A-7-231074).
However, due to size reduction and sophistication of a portable phone, there is a need to reduce a size of a camera module, particularly to a reduction in height dimension and footprint thereof.
As a measure for satisfying the need, there has been pursued a design for reducing a dimension of an optical system (a dimension between the image pickup element and a lens top surface) occupying a great part of the height of the camera module by reducing a pixel size of the solid-state image pickup element.
In order to reduce the footprint and cost of the camera module, there has been pursued an improvement to a chip circuit configuration of a CCD image sensor and a device (a digital signal processor: a DSP) configured to electrically correct an output signal of the CCD image sensor so as to correct a resolution, a color tone, shading, etc., of a camera. In addition, there has become widely used a so-called system-on-chip (SOC) solid-state image pickup element including a circuit having a DSP function disposed around a solid-state image pickup element manufactured by use of a CMOS process.
Even when a glass substrate is used as a light-transmitting substrate 101, a trace (a metal trace) 102 using a metal film formed by a thin film deposition process or an electroless plating process has been used. In the light-transmitting substrate 101, since light hardly passes through the metal film, the trace 102 has to be formed at regions except a light receiving area 105 of a solid-state image pickup element 106 (see
Consequently, there has been a problem of an increase in the footprint of the camera module substrate, which can not satisfy the need for reduction of the size and thickness of the solid-state image pickup device can not be satisfied.
The present has been made in view of the above circumstances, and an object thereof is to provide a solid-state image pickup device with reduced size and thickness.
A solid-state image pickup device of an aspect of the present invention uses an optically-transparent conductive pattern as a trace, in place of the related art technique of forming optically opaque patterns over the glass substrate and flip-mounting the solid-state image pickup element. Consequently, since the present aspect uses the optically-transparent conductive pattern, the trace can be routed over the light receiving area, thereby increasing a degree of freedom of trace routing and substantially reduce the size of the solid-state image pickup device.
In one aspect, a solid-state image pickup device includes a terminal electrode and an inside electrode which are formed on a grass substrate. The terminal electrode is configured to output an electric signals to outside, and the inside electrode provided used for bonding the solid-state image pickup element to the glass substrate by a conductive adhesive. The terminal electrodes and the inside electrodes are connected by an optically-transparent conductive trace formed across an upper surface of a light receiving area of the solid-state image pickup element. A region of a gap between the solid-state image pickup element and the glass substrate except the light receiving area of the solid state image pickup element is sealed with a sealing resin.
Specifically, a solid-state image pickup device may includes: a light-transmitting substrate including a terminal electrode for external connection, an inside electrode for bonding a solid-state image pickup element, and a trace that connects the terminal electrode to the corresponding inside electrode; and the solid-state image pickup element which is placed such that a light receiving area opposes the light-transmitting substrate and which is connected to the inside electrode, wherein the trace is made of a light-transmitting conductive film at least in a region opposing the light receiving area of the solid-state image pickup element.
In the configuration, the trace connecting the inside electrode to the terminal electrode is made of the light-transmitting conductive film, and the trace is provided on the light receiving area. Consequently, the degree of freedom of trace routing is increased, and the size of the solid-state image pickup device can be substantially reduced.
In the solid-state image pickup device, a region of a gap between the solid-state image pickup element and the light-transmitting substrate except the light receiving area of the solid-state image pickup element may be filled with a sealing resin.
With this configuration, a moisture content can be prevented from entering into the solid-state image pickup element, and an additional protective material is not required. Therefore, the size of the solid-state image pickup device can be reduced.
In the solid-state image pickup device, the light receiving area of the solid-state image pickup element may have a rectangular shape, and the trace obliquely may run across a corner portion of the rectangular shape.
In the configuration, the traces are formed in a periphery of the light receiving area of the solid-state image pickup element, and a degree of freedom of trace routing can be enhanced without adversely affecting an image pickup characteristic of the solid-state image pickup element.
In the solid-state image pickup device, the terminal electrode may be arranged along a side of the light-transmitting substrate.
In the configuration, the terminal electrode formation area can be increased, and mounting work is improved.
In the solid-state image pickup device, the inside electrode may be arranged along opposing two sides of the solid-state image pickup element.
According to the configuration, the trace is formed so as to run across the light receiving area of the solid-state image pickup element. For this reason, even when the inside electrode is formed along two opposing sides and when the terminal electrode is formed along the other sides, the length of the traces that connect the inside electrode to the terminal electrode can be reduced, and the traces with high reliability can be provided.
In the solid-state image pickup device, the light-transmitting substrate may be a glass substrate.
The configuration prevents entry of a moisture content, to thus realize chemical stability. Therefore, it is possible to provide a highly-reliable solid-state image pickup device.
In the solid-state image pickup device, at least an upper surface of the trace opposing the light receiving area of the solid-state image pickup element may be made of a light-transmitting conductive film, and in a region other than the light receiving area, the trace may be made of a metallic film.
In the configuration, the trace is made of a light-transmitting conductive film in the light receiving area. In an area other than the light receiving area, the trace is made of a metallic film. As a result, it is possible to provide a semiconductor device with a high degree of design freedom while an increase in trace resistance is prevented to the maximum extent.
In the solid-state image pickup device, the light-transmitting conductive film may be made of an indium tin oxide layer.
With this configuration, it is possible to obtain superior transparency at low resistance.
In the solid-state image pickup device, a plurality of solid-state image pickup elements may be placed on the light-transmitting substrate.
With this configuration, even when the trace becomes complicate, the trace can be efficiently routed at the minimum trace length. Therefore, a footprint required for trace routing is reduced, which can accomplish size reduction. Further, a reduction in trace resistance can increase operating speed.
In the solid-state image pickup device, the plurality of solid-state image pickup elements may be integrated on a single substrate, and in a region opposing the solid-state image pickup elements, the trace may be provided so as to oppose a trace area that surrounds the light receiving areas of the respective solid-state image pickup elements.
According to the configuration, the trace is formed, for example, on the charge transfer unit, whereby trace routing can be facilitated while a reduction in the amount of received light is prevented.
In the solid-state image pickup device, each of the solid-state image pickup elements may include a photoelectric conversion unit including a photodiode and a charge transfer unit configured to transfer electric charges produced by the photoelectric conversion unit, and in the region opposing the solid-state image pickup elements, the trace may be formed in a region opposing the charge transfer units.
In the solid-state image pickup device, the light-transmitting substrate may include an optical filter configured to permit transmission of light having a specific wavelength band and a light shielding film formed in a region corresponding to a boundary between a plurality of image pickup areas.
In the configuration, the light-transmitting substrate includes both the optical filter and the light shielding film that defines the image pickup areas. Hence, a small and thin solid-state image pickup device can be provided.
In another aspect, a method for manufacturing the solid-state image pickup device includes: a step of positioning a projecting electrode formed at a connection terminal of the solid-state image pickup elements to the inside electrode of the light-transmitting substrate and bonding the projecting electrode to the inside electrode by a conductive adhesive; and a step of sealing the region of the solid-state image pickup element except the light receiving area thereof.
According to the method, it is possible to easily produce a highly-reliable solid-state image pickup device.
In the method for manufacturing the solid-state image pickup device, the light-transmitting substrate may include: the glass substrate; the optical filter which is formed on a surface of the glass substrate opposing an adhesive surface of the solid-state image pickup element and which is configured to permit transmission of light having the specific wavelength band; and the light shielding film formed in the region corresponding to the boundary between the plurality of image pickup areas, and the sealing step may include a step of sealing the region, except the light receiving area of the solid-state image pickup element, with a photo-curable resin that causes a curing reaction at the transmission wavelength band of the optical filter after the bonding step.
With this configuration, a highly reliable solid-state image pickup device can be produced without entry of a resin into the light receiving areas.
As described above, according to aspects of the present invention, the traces are formed by use of an optically transparent conductive pattern, thereby making it possible to route the traces over the light receiving areas. This results in an increase in degree of freedom of trace routing, which makes it possible to reduce the size of the solid-state image pickup device.
Embodiments of the present invention are described below in detail by reference to the drawings.
A solid-state image pickup device of a first embodiment is described by reference to
The solid-state image pickup device of the first embodiment of the present invention uses an optically transparent conductive pattern as a material of traces 2 that connect terminal electrodes for outputting an electric signal to the outside to inside electrodes 3 for bonding a solid-state image pickup element 5 to a glass substrate serving as a light-transmitting substrate 1. The traces 2 can be routed on a light receiving area 6, so that a degree of freedom of the traces 2 can be increased, to thus substantially reduce the size of the solid-state image pickup device.
Specifically, as shown in
Specifically, the solid-state image pickup device of the embodiment includes the light-transmitting substrate 1 and the solid-state image pickup element 5 as shown in the schematic diagram of top view shown in
As shown in
The light-transmitting conductive film is formed, for example, by a method described below.
First, a photosensitive resin film is formed by means of a wet coating technique.
After having been pre-baked, the resin film is exposed to UV radiation using a high voltage electric discharge lamp, or the like through a predetermined mask. The resin film is then developed and sintered, whereby the traces 2 made of indium tin oxide (ITO), or the like, are formed.
The solid-state image pickup element 5 and the traces 2 of the light-transmitting substrate 1 are overlapped so as to oppose each other. The solid-state image pickup element 5 and the inside electrodes 3 connected to the traces 2 are electrically connected electrical connection portions 14 (a connection portions between electrode pads forming the inside electrodes 3 of the glass substrate and metallic bumps 15 of the solid-state image pickup element). A periphery of the electrical connection portions 14 is sealed with an insulating sealing resin 7.
The solid-state image pickup element 5 is mounted on the light-transmitting substrate 1, and the insulating sealing resin 7 is injected therebetween. As is apparent from
The light-transmitting substrate 1 on which the solid-state image pickup element 5 and the solder balls 8 are mounted is inverted and solder-mounted to a printed wiring board 9, and the strength of the light-transmitting substrate 1 is reinforced by an underfill (a sealing resin) 10. Here, the insulating sealing resin 7 injected in a preceding process is exposed outside. In this state, a lens housing 12 including a plurality of lenses 11 is prepared from above. A surface of the light-transmitting substrate 1 where the solid-state image pickup element 5 is not mounted is taken as a reference surface, and the lens housing 12 is mounted on the reference surface. The lens housing 12 is integrated with the printed wiring board 9, whereby a solid-state image pickup device is completed.
In the embodiment, the solid-state image pickup element is solder-mounted directly to the printed wiring board by the solder balls. However, an indirect conduction method for placing a conductive member sandwiched between a printed wiring board and a solid-state image pickup element may be used in view of the thickness of the solid-state image pickup element. Alternatively, a method for grinding a printed wiring board or drilling a through hole may be used.
The light-transmitting substrate 1 is mounted on the surface of the printed wiring board 9 through the solder balls 8. Strength of a periphery of the solder balls 8 is reinforced by the underfill 10. The solid-state image pickup element 5 including the image pickup area (the light receiving area) 6 having integration of two image pickup areas is mounted on the light-transmitting substrate 1 through the electrical connection portions 14. The insulating sealing resin 7 is injected in full measure into a periphery of the light-transmitting substrate 1 and cured. Further, in a manufacturing method of the embodiment to be described later, the insulating sealing resin 7 does not leak to the image pickup area (the light receiving area) 6 of the solid-state image pickup element 5.
A surface of the light-transmitting substrate 1 that is not equipped with the solid-state image pickup element 5 is taken as a reference surface, and the lens housing 12 include the lenses 11 is mounted on the reference surface.
Since the image pickup device has such a structure, optical information captured by the compound lens 11, i.e., light does not leak to an adjoining area and enters the image pickup area (the light receiving area) 6 of the solid-state image pickup element 5 mounted on the light-transmitting substrate 1 with superior accuracy while a distance from the light-transmitting substrate 1 is made constant with superior accuracy. Moreover, adhesion strength between the solid-state image pickup element 5 and the light-transmitting substrate 1 and adhesion strength between the light-transmitting substrate 1 and the printed wiring board 9 are sufficiently reinforced and assured by the insulating sealing resin 7 and the underfill 10. The solid-state image pickup element 5 is connected to the light-transmitting substrate 1 by the metal bumps 15 provided on the electrode wiring pads (not shown) provided around the image pickup area in correspondence with the image pickup area without routing traces within the solid-state image pickup element 5. Therefore, the solid-state image pickup element can be connected directly to the traces on the light-transmitting substrate 1 from the image pickup area (the light receiving area) 6. Accordingly, bumps will not concentrate on the periphery of the solid-state image pickup element substrate (chip), and it also becomes possible to prevent occurrence of noise caused by useless routing of traces.
The light-transmitting substrate 1 has L0 wide and L2 long with respect to a light receiving area L1. When compared with a related art light-transmitting substrate 101 having L4 wide and L5 long as shown in
That is, implementation of the embodiment is understood to be effective for reducing the size of the solid-state image pickup device.
A substrate coated with an optical filter film or an antireflection film may be used as the light-transmitting substrate 1. In this case, an optical characteristic can be enhanced to a greater extent.
In the solid-state image pickup device, the terminal electrodes are configured so as to obliquely run across a corner portion of the rectangular light receiving area of the solid-state image pickup element. Hence, even when the inside electrodes arranged along the respective sides of the light-transmitting substrate are routed along opposing two sides of the solid-state image pickup element, a degree of freedom of trace routing can be enhanced without adversely affecting an image pickup characteristic of the solid-state image pickup element.
According to the embodiment, in the solid-state image pickup device, a plurality of solid-state image pickup elements are mounted on the light-transmitting substrate.
With this configuration, even when traces become complicate, the traces can be efficiently routed at the minimum trace length. Therefore, a footprint required for trace routing can be reduced, thereby reducing the size of the solid-state image pickup device. In addition, a reduction in trace resistance can increase operating speed.
In the embodiment, the plurality of solid-state image pickup elements may be integrated on a single substrate in the solid-state image pickup device. In this case, in a region opposing the solid-state image pickup element, the traces are routed so as to oppose a trace area surrounding the light receiving area of the solid-state image pickup element.
In the configuration, for example, traces are formed on an electric charge transfer unit, whereby trace routing can be facilitated while a reduction in a quantity of received light is prevented.
In the embodiment, for manufacturing the solid-state image pickup device, projecting electrodes formed at connection terminals of the solid-state image pickup elements are positioned to the inside electrodes of the light-transmitting substrate, the projecting electrodes are bonded to the inside electrodes by a conductive adhesive, and the region of the solid-state image pickup element except the light receiving area thereof is sealed. At the sealing operation, the region of the solid-state image pickup element except the light receiving area thereof is sealed with a photo-setting resin that causes a curing reaction at a transmission wavelength band of the optical filter.
According to the method, it is possible to form a highly-reliable solid-state image pickup device without entry of a resin into the light receiving area.
A second embodiment of the present invention is now described.
In the previous embodiment, the traces on the glass substrate are made of a light-transmitting conductive film. However, at least upper surfaces of the traces opposing the light receiving area of the solid-state image pickup element may be made of a light-transmitting conductive film. In the present embodiment, traces in a region of the solid-state image pickup element except the image pickup area (the light receiving area) are made of a metallic film.
According to the configuration, traces in the light receiving area are made of a light-transmitting conductive film. In the other regions, the traces are made of a metallic film, whereby a semiconductor device exhibiting a high degree of design freedom can be provided while an increase in trace resistance is reduced to the maximum extent.
A third embodiment of the present invention is now described.
Although the previous embodiments describe the case in which the number of the light receiving area is one, the present embodiment describes a case in which a solid-state image pickup element having a plurality of image pickup areas (light receiving areas) is used.
In the present embodiment, a plurality of solid-state image pickup elements are integrated on a single substrate, and in the area opposing the solid-state image pickup element, the traces are routed so as to oppose a trace area surrounding the light receiving areas of the solid-state image pickup element.
A solid-state image pickup device of the third embodiment is described by reference to
As illustrated in the top view of the substrate shown in
Specifically, as shown in
Specifically, as shown in a schematic explanatory external view shown in
As shown in
With this configuration, for example, traces are formed on the electric charge transfer units. Thus, trace routing can be facilitated while a reduction in an amount of received light is prevented.
Since the two image pickup areas (light receiving areas) 36 are formed on a single semiconductor substrate, the image pickup areas have a highly accurate base length. As a result, an extremely high accurate distance measuring characteristic can be provided.
As described above, it is possible to obtain a solid-state image pickup device that exhibits a superior image pickup characteristic, a highly accurate distance measuring characteristic, and high reliability of electrical connection obtained from high strength. Specifically, it is effective to apply the solid-state image pickup device to a vehicle-mounted camera requiring distance measuring function and high reliability.
In the embodiments of the present invention, the integrated solid-state image pickup elements including two image pickup areas formed on a semiconductor substrate are described. However, when the present invention is applied to a solid-state image pickup device including three image pickup areas or more formed on a semiconductor substrate in an integrated fashion thereby exhibiting an improved image pickup characteristic and an enhanced added value, it is possible to obtain a highly accurate, highly reliable solid-state image pickup device and a method for manufacturing the same.
In this case, bumps may be formed by making electrode wiring pads around each image pickup area. When a plurality of image pickup areas are arranged, a method including adjusting areas for forming electrode wiring pads as necessary and forming the electrode wiring pads for each of the plurality of image pickup areas may be also applicable.
In the embodiment, a glass substrate is used as a light-transmitting substrate. However, the material of the substrate is not limited to glass, and a light-transmitting resin substrate may be used.
To be more precise, the term “light receiving area” used in the present embodiment is defined to designate a light receiving area of a solid-state image pickup element, i.e., an image pickup area. For example, when a solid-state image pickup element includes a plurality of pixels, it is not necessary to form regions between pixels by a light-transmitting conductive film so long as a light-transmitting conductive film is formed on the pixels.
In addition to indium tin oxide, tin oxide, zinc oxide, or the like, may be applied to the light-transmitting conductive film. A film forming technique using the photosensitive ITO paint described in the embodiments is effective as a method for forming a light-transmitting conductive film. However, another sputtering technique, a vacuum deposition technique, a sol-gel technique, a cluster beam deposition technique, a PLD technique, an inkjet plotting technique, and the like, are also applicable.
The present patent application is based on Japanese Patent Application (Application No. 2009-258226) filed on Nov. 11, 2009, the entire contents of which are incorporated herein by reference.
According to the solid-state image pickup device of the present embodiments, it is possible to route traces on light receiving areas by forming the traces from an optically transparent conductive pattern. A degree of freedom of trace routing is increased, and it is possible to reduce a size of a solid-state image pickup device. Thus, the solid-state image pickup device can be easily applied to a compact camera, etc. of a portable terminal, etc.
1, 31: LIGHT-TRANSMITTING SUBSTRATE
2, 32: TRACE
3, 33: INSIDE ELECTRODE
4, 34: TERMINAL ELECTRODE
5, 35a, 35b: SOLID-STATE IMAGE PICKUP ELEMENT
6, 36: IMAGE PICKUP AREA (LIGHT RECEIVING AREA)
7: INSULATING SEALING RESIN
8: SOLDER BALL
9: PRINTED WIRING BOARD
10: UNDERFILL
11: LENS
12: LENS HOUSING
14: ELECTRICAL CONNECTION PORTION
15: METAL BUMP
43: LIGHT SHIELDING WALL
44: LENS
50: HOUSING
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-258226 | Nov 2009 | JP | national |
This application is a continuation of International Application No. PCT/JP2010/006574, filed on Nov. 9, 2010, which claims priority from Japanese Patent Application No. 2009-258226 filed on Nov. 11, 2009, the disclosures of which Applications are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2010/006574 | Nov 2010 | US |
| Child | 13242654 | US |
