JPS6074880A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To improve both packing density and image resolution of a solid-state image pickup device with a compact design by forming a conductor on the side surface of a semiconductor chip to secure the connection between a photodetecting semiconductor element and a signal processing circuit element. CONSTITUTION:A photodetecting semiconductor area 31a and a signal processing semiconductor area 31b are formed on both sides of a single semiconductor chip 31. The area 31a includes a charge coupled semiconductor element such as a CCD, etc. and a semiconductor image pickup element like an MOS transistor array, etc. At the same time, a color filter film is formed on the surface of the area 31a. Then an area 32 is connected to an area 33 by a conductor 34 formed by vapor-depositing a metal on the side surface of the chip 31 in order to perform transfer of signals between the areas 31a and 31b.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a solid-state imaging device, and particularly to a solid-state imaging device suitable for being incorporated into an endoscope for observing the inside of a body cavity or a mechanical structure. be.

Conventional technology A conventional endoscope has a light guide and an image guide made of an optical fiber bundle extending inside a flexible outer tube that is inserted into a subject, and emits light from an external illumination source. The light is guided through the light guide to the tip of the endoscope, and is irradiated onto the subject through the illumination lens system.The image of the subject is guided to the outside via the objective lens system and image guide, and then directly through the eyepiece system. They are either observed or captured with an imaging device and displayed on a monitor. The resolution of conventional endoscopes using such image guides is determined by the diameter of the fibers that make up the image guide, but it is extremely difficult to make the fiber diameter even thinner than it currently is, and the resolution is almost at its limit. has reached. Furthermore, since the image guide is easily damaged, there is also a problem in terms of durability.

In order to solve these problems, a small imaging device is built into the tip of the endoscope, which captures the image of the subject and converts it into an image signal.This image signal is led to the outside via a conductor and displayed on a monitor. It has been proposed to display the image of the subject. Imaging devices include OCD, BBD, MOS
-FET ARRAY, PIN -PH0TODIOD
Semiconductor solid-state imaging devices such as EARRAY and SIT ARRAY have been developed, and these solid-state imaging devices are small, have high resolution, and have a long lifespan. suitable for However, although currently manufactured solid-state imaging devices are smaller than conventional imaging tubes, it is difficult to incorporate them into the tip of an endoscope as is. In particular, endoscopes for observing inside body cavities, even the largest diameter rectoscope, have a diameter of about 10-odd millimeters, and cannot incorporate current solid-state imaging devices. Such problems are not limited to endoscopes, and may also occur in other imaging devices.

Since the detection signal from the photodetecting semiconductor element that constitutes the semiconductor solid-state imaging device R is weak, generally the semiconductor imaging device is mounted with a signal processing circuit element that constitutes an amplifier circuit that amplifies the detection signal, rather than using the element alone. is becoming more widely used. In this case, the photodetector semiconductor element and the signal processing circuit element may be configured in a single semiconductor chip or in multiple semiconductor chips. FIG. 1 shows the configuration of an example of a conventional solid-state imaging device. In the example shown in FIG.
Charge transfer elements such as OOD t and BBD are connected to L.

MOS) Photodetection semiconductor elements such as Langistau photodiodes, phototransistors, and electrostatic conductive transistors are formed, and the right part 2R is connected to horizontal and vertical shift registers, address registers, various selection holes, and video lines. load resistance.

Signal processing circuit elements constituting capacitors, amplifiers, etc. are formed. A light-shielding film or a light-shielding plate 8 is provided above the portion 2R where the signal processing circuit element is formed. This prevents the negative effects of minute hidden currents from reaching the signal processing circuit.

Signals are exchanged between the photodetecting semiconductor element and the signal processing circuit element via a semiconductor region or a conductive pattern,
Output signals from the signal processing semiconductor region, control signals from external circuits, etc. are exchanged via leads 5, bonding bats 6 provided on ceramic substrate 1, and conductive wires 7.

In a solid-state imaging device with such a configuration, the photodetection semiconductor element and the signal processing circuit element can be formed in a single semiconductor chip I, so the size can be made smaller than when these are formed in separate semiconductor chips. However, it is not small enough to be built into the tip of an endoscope. In addition, heat generated in the amplifier circuit, etc. in the signal processing circuit is transferred to the photodetection semiconductor element, increasing dark current, and carrier charges generated by light incident on the photodetection area are transferred to the amplifier circuit and its peripheral circuits. This is a major problem, and since the photodetector semiconductor element and the signal processing circuit element are configured on a single semiconductor chip, it is difficult to match the characteristics and the chip manufacturing process. !There will be an increase in costs.

Technical Background In order to solve the above-mentioned problems, the applicant has proposed a mounting method called back bonding as shown in FIG. 2 in Japanese Patent Application No. 58-46967. In FIG. 2, the photodetecting semiconductor element is formed on the upper semiconductor chip 11, the signal processing circuit element is formed on the lower semiconductor chip 2, and these chips are integrated with the insulating holder 18 into the partition wall 14. are supported and spaced apart by. Contact pads 15 and 16 formed on the surfaces of semiconductor chips 11 and 12 are connected to the front and back sides of holder 8 via conductive wires 7 and 18 for transmitting and receiving signals between the photodetector semiconductor element and the signal processing circuit element. Contact pads provided】9 and 20
Roughly connect these contact pads 19 and 2 to
0 by a lead 21 extending from the side surface of the holder 18).

A lead 22 for connecting the solid-state imaging device to an external circuit extends from the holder ]8. In an actual solid-state imaging device, the entire structure shown in FIG. 2 is roughly housed in a package, but the package is not shown in FIG.

In the back junction structure shown in FIG.
4 are stacked one on top of the other with 4 in between, so the area seen from the incident light side is smaller than that of the conventional solid-state imaging device shown in Figure 1, and the problems of heat effects and carrier charge diffusion are solved. However, it is practically impossible to incorporate it into the endoscope as it is. That is, the diameter of the endoscope is very small, and there is not enough space to incorporate the solid-state imaging device. For example, in an endoscope for observing inside body cavities, in addition to the above-mentioned light guide, forceps for collecting specimens and wires for operating them are inserted, and the leading lens of a single objective lens system is inserted. A water supply tube for cleaning and an air supply tube for blowing off the cleaning water adhering to the leading lens and inflating the body cavity are also inserted, and the space available for housing the solid-state imaging device is extremely limited. There is. Therefore, in order to incorporate a high-resolution solid-state imaging device into an extremely narrow space such as the tip of an endoscope, there are 1. .

It is necessary to improve the structure of the solid-state image sensor itself, but there are various issues such as the coupling and arrangement of the photodetector semiconductor chip and the signal processing semiconductor chip, the coupling of signal lines between the bidirectional conductor chips, the packaging method, and the method of leading out the leads. We have to solve 11 difficult problems.

The object of the present invention is to eliminate the above-mentioned conventional drawbacks, to be able to have a compact structure, to improve the packaging density and increase the resolution, and to be able to be incorporated into an endoscope tip with an extremely small diameter. In particular, the present invention aims to provide a solid-state imaging device suitable for being incorporated into the tip of an endoscope.

The solid-state imaging device according to the present invention has a photodetecting semiconductor element and a signal processing circuit element formed on the side surface of at least one semiconductor chip, in which the photodetecting semiconductor element and the signal processing circuit element are formed on the front and rear sides when viewed from the direction of incident light. It is characterized by forming a conductor for interconnection between the two.

Example Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 8 is a diagram showing the configuration of an embodiment of the solid-state imaging device of the present invention. In this example, a photodetecting semiconductor region 81a and a signal processing semiconductor region 81b are provided on the front and back sides of a single semiconductor chip 8.
The photodetecting semiconductor region 81a includes COD, BB.
Charge-coupled semiconductor devices such as D.

MOS) Semiconductor imaging devices such as transistor arrays, pin photodiode arrays, phototransistor arrays, and EWI transistor arrays are formed, and a mosaic color filter film is formed on the surface with an insulating film interposed therebetween. , an insulating film, a nine-color filter film, and the like are omitted. Furthermore, although semiconductor elements constituting horizontal and vertical shift registers, amplifier circuits, switches, etc., and passive elements such as load resistors and capacitors are formed in the signal processing semiconductor region 81b, illustration thereof is also omitted. In the present invention, in order to transmit and receive signals between the photodetection semiconductor region 81a and the signal processing semiconductor region 81b, a metal layer is provided on the side surface of the semiconductor chip 81 between the regions 82 and 33 formed on the surface of these regions. A conductor 8 formed by vapor deposition of
Connect by 4. Furthermore, a glue 35 is fixed to the back surface of the semiconductor chip 81 for transmitting and receiving signals between the solid-state imaging device and an external circuit. In the present invention, the connection between the photodetection semiconductor element and the signal processing circuit element is made on a semiconductor chip (
By using a conductor attached to the III surface,
The dimensions of the solid-state imaging device viewed from the incident light side can be made smaller. Further, since the entire back surface of the semiconductor chip can be used for connecting leads, a large number of leads can be easily connected.

FIG. 4 is a schematic sectional view showing another solid-state N image device of the present invention. In this example, a photodetector semiconductor element is formed in the region 4Ia of the semiconductor chip 41, and a signal processing circuit element is formed in the region 42a of the semiconductor chip 42. These semiconductor chips 41 and 42 are stacked one on top of the other with an insulating member 48 of appropriate thickness in between when viewed in the direction of incident light. A predetermined area 44 of the semiconductor chip 41 is
A conductor 45 formed on the side surface of the insulating member 48 by metal vapor deposition is connected to a predetermined region 46 formed on the semiconductor chip 42 . In this example, since the semiconductor chip 41 on which the photodetection semiconductor region is formed and the semiconductor chip 42 on which the signal processing circuit is formed are configured separately, there is no need to match the circuit characteristics with the semiconductor chip manufacturing process. It is possible to eliminate the adverse effects caused by carrier charges, and since the leads are provided on the back side, the lateral dimension as viewed from the light incident direction can be reduced, and the packaging density can be improved.

Roughly speaking, in this example, a contact area #247 is provided on the back surface of the semiconductor chip 42 without directly bonding the leads to the back surface of the semiconductor chip 42, and the attachment is performed using the leads 49 attached on the fourth day of the substrate.
Abut the tip of the contact area on the contact area to make an electrical connection. By attaching the leads to a substrate as in this example and attaching this substrate to the back surface of the semiconductor chip, the mechanical strength of the leads is increased and electrical connection of the leads can be easily made.

FIG. 5 is a schematic perspective view showing roughly another example of the solid-state imaging device of the present invention. In this example, a semiconductor chip 51 on which a photodetection semiconductor element is formed and a semiconductor chip 52 on which a signal processing circuit element is formed are placed one on top of the other when viewed in the direction of incident light, as in the previous example. The connection between the semiconductor chips 5 and 52 is made by a conductor 58 formed by metal vapor deposition on the side surfaces of these semiconductor chips. In this example, in order to connect the solid-state imaging device to an external circuit, a hole is made in the semiconductor chip 52 on the rear side, and the tip of the lead wire 54 is inserted into the hole and soldered. FIG. 6 is an enlarged cross-sectional view showing the connecting portion between the semiconductor chip 52 and the lead wire 54. A hole 56 is formed in a predetermined area 55 on the surface of the semiconductor chip, and the conductor core 54a of the lead wire 54 is inserted into the hole. is inserted, and the first region 55 and the conductor core 54a are connected by solder 57. With this configuration, the lead wires 54 do not protrude outward from the semiconductor chip 52, so the dimensions seen from the direction of incident light can be reduced, and drowsy connections can be easily and reliably performed. This reduces the occurrence of trouble.

FIG. 7 is a sectional view showing the configuration of an example of an endoscope incorporating the above-described solid-state imaging device of the present invention at its tip. The endoscope of this example is a direct-view type for observing the inside of a body cavity, and a tip body 62 made of stainless steel, for example, is fitted to the tip of a flexible outer tube 61 that is inserted into the subject. This tip body 62 has several channels 62a, 62b, 620.
... is formed. A light guide 68 made of an optical fiber bundle is inserted into the light guide channel 62a, and a concave lens 64 is fitted at the tip. light guide 6
8 is covered with a cover tube 65', extends inside the outer cylinder 61, leads to the operating section, and is connected to the illumination light source. An objective lens system 66 is provided at the tip inside the objective observation channel 62b.
At the same time, the solid-state imaging device 67 is fitted inside.

The solid-state imaging device 67 of this example has the configuration shown in FIG. 4, and has two semiconductor chips stacked one above the other.

A conductive wire bundle 69 is connected to the leads 68 attached to the back surface of the rear semiconductor chip, and this conductive wire bundle 69 is connected to the flexible tube 7.
0, the inside of the outer cylinder is extended to the operating section, and connected to the signal processing circuit. An air supply tube 71 is connected to the air supply channel 62c, and an air supply nozzle 72 is attached to the tip thereof, so that air can be supplied toward the leading lens of the objective lens system 66. A water supply tube is connected to the water supply channel, a water supply nozzle is provided at the tip, and an objective lens system 66 is installed.
Water is supplied to the leading lens to wash away dirt, etc., but the water supply tube and water supply nozzle are not shown in FIG. Further, the air supply nozzle 72 blows away the cleaning water adhering to the leading lens and, if necessary, blows air into the inside of the subject to inflate it. A forceps channel is roughly formed in the tip body 62,
A forceps for collecting a specimen sample and a wire for operating the forceps from the outside can be inserted through this hole.

A thread groove is formed on the outer circumferential surface of the tip main body 62, and a tip hood 78 is screwed therein.

The present invention is not limited to the embodiments described above, and many modifications are possible. For example, in the embodiment shown in Fig. 3, the leads are connected directly to the back surface of the semiconductor chip, but as shown in Fig. 4, the leads are fixed to the substrate, and the mounting method is to connect the board to the back surface of the semiconductor chip. 6Also, the conductor extending to the side surface of the semiconductor chip can be formed on all the sides of the semiconductor chip,
It is advantageous in manufacturing not to form a conductor on at least one side surface. In general, the solid-state imaging device of the present invention can be incorporated not only in the direct-viewing endoscope shown in FIG. 7, but also in a side-viewing endoscope. Furthermore, in the above-mentioned endoscope, the light from the light source is emitted from the tip of the outer tube through a light guide, but it is also possible to install a light source such as a lamp or a light emitting diode at the tip of the outer tube without using a light guide. It can also be configured to illuminate the subject using the same method. In this case, red, blue.

It is also possible to use light-emitting diodes of eight green colors and make them emit light in sequence. In this case, a color filter provided on the light-receiving surface of the solid-state imaging device becomes unnecessary. In general, it goes without saying that the solid-state imaging device of the present invention can be incorporated into imaging equipment other than (1) endoscopes;

According to the present invention, the photodetection semiconductor element and the signal processing circuit element are formed in front and behind each other when viewed from the direction of incident light, and the space between the photodetection semiconductor element and the signal processing circuit element is formed on the side surface of the semiconductor chip. By making the lateral dimension as seen from the direction of the incident light almost the same as the dimension of the light-receiving surface, it can be effectively incorporated into the tip of a small-diameter endoscope, for example. be able to. Furthermore, attaching the leads to the back side of the semiconductor chip greatly contributes to miniaturization, facilitates manufacturing, and has the effect of improving electrical characteristics.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of an example of a conventional solid-state imaging device, FIG. 2 is a sectional view showing the configuration of a back junction type solid-state imaging device previously proposed by the applicant, and FIG. 8 is a sectional view showing the configuration of an example of a conventional solid-state imaging device. FIG. 4 is a diagrammatic cross-sectional view showing the configuration of another example of the solid-state imaging device of the present invention, and FIG. 5 is a diagram showing the configuration of another example of the solid-state imaging device of the present invention. FIG. 6 is a cross-sectional view showing an enlarged portion of the configuration, and FIG. 7 is a cross-sectional view showing an example of an endoscope incorporating the solid-state imaging device of the present invention inside its tip. be. 81...Semiconductor chip 82.88...Region 84.
...Conductor 85...Lead 41.42...Semiconductor chip 43...Insulating member 44.46.47...Region 45
...Conductor 49...Lead 51.52...Semiconductor chip 58...Conductor 54...Lead wire 55...Region 56...Hole 57...Solder patent applicant Olympus Optical Co., Ltd. Co., Ltd.Figure 1Figure 2Figure 3Figure 4Figure 5Figure 6Figure 7Figure 7Continued from page 10Inventor Hiroshi Kamihara Hatagaya Co., Ltd., Shibuya-ku, Tokyo0Inventor Ohashi − Tsukasa 0 origin in Hatagaya Co., Ltd., Shibuya-ku, Tokyo Author Hiroyuki Yashima 0 origin in Hatagaya Co., Ltd., Shibuya-ku, Tokyo Author Mototsugu Ogawa 0 origin in Hatagaya Co., Ltd., Shibuya-ku, Tokyo Author Hiroyuki Fujimori 0 Inventor, Hatagaya Co., Ltd., Shibuya-ku, Tokyo Author: Yama 1) Hidetoshi 0 Inventor, Hatagaya Co., Ltd., Shibuya-ku, Tokyo Author: Masaru Iino 2-4-2, Hatagaya Co., Ltd., Shibuya-ku, Tokyo, Japan Olympus Optical Industry 2 Olympus Optical Industry 2nd term 4th hour 2nd edition Olympus Optical Industry 2nd term 4th hour 2nd edition Olympus Optical Industry 2nd term 4th hour 2nd edition Olympus Optical Industry 2nd term 4th hour 2nd edition Olympus Optical Industry 2nd term Ryome 4 旙2 No. 2 Olympus Optical Industry

Claims (1)

[Scope of Claims] L A photodetecting semiconductor element and a signal processing circuit element are formed on the side surface of at least one semiconductor chip formed in front and behind the photodetecting semiconductor element and the signal processing circuit element when viewed from the direction of incident light. A solid-state imaging device characterized in that a conductor is formed for interconnection between the two. 2. The photodetection semiconductor element and the signal processing circuit element are each formed on separate semiconductor chips, and these semiconductor chips are placed one on top of the other with an insulating member in between when viewed in the direction of incident light, and the photodetection semiconductor element and 2. The solid-state imaging device according to claim 1, wherein a conductor for interconnection with a signal processing circuit element is formed on a side surface of the amphibodiconductive chip and the insulating member. & The solid-state imaging device according to claim 1 or 2, characterized in that a lead for connecting the solid-state imaging device to an external circuit is provided on the back surface of the semiconductor chip.