JP2010273757A - Image sensor applied device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems of an image sensor applied device for acquiring image information by a mounted image sensor, wherein there are limits to high resolution, high sensitivity, and miniaturization of the contour of the device because a rectangular image sensor is mounted within the device whose cross section is circular. <P>SOLUTION: The image sensor applied device has an imaging device which is mounted at the distal end of a tube made of metal, etc. and composed at least of a lens, the image sensor, and an image processing IC. The shape of the image sensor is circular, or polygonal with five or more angles. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image sensor application apparatus for obtaining image information in a narrow space. More specifically, the present invention relates to an image sensor application apparatus and an observation apparatus using an image sensor used in the medical equipment field and the industrial measurement field.

  In recent years, there has been an increasing demand for image sensor application devices using images in the medical device field and industrial measurement field. For example, in the field of medical equipment, so-called “one-day surgery” using a laparoscope or a cannula (insertion tube into the body) has started to spread without performing a laparotomy. In this case, a plurality of holes of several millimeters size are made in the abdomen, a plurality of devices are inserted into the body from here, and the treatment is performed while observing images. An image sensor application apparatus for such a purpose is also referred to as an endoscope, and an image is optically transmitted from an apparatus tip (also referred to as a distal end) through an optical fiber or a relay lens to the proximal portion (proximal end) of the apparatus. (Also referred to as a “simply”) and provide images to the practitioner with the naked eye or a TV camera. Also, in the industrial equipment field, an image sensor application device (also called “borescope”) with a structure similar to an endoscope is used to inspect damage in factory plant piping and prevent accidents. Yes. In general, the “borescope” includes a straight pipe type and a flexible type. In the former, a relay lens is mounted inside a stainless steel straight tube having a diameter of about 6 mm. In the latter case, tens of thousands of small-diameter (several micrometers) glass fibers are bundled inside a flexible stainless steel tube (bellows tube) that can be bent freely. This configuration is also called “fiberscope”. However, in these image sensor application apparatuses, since the image is optically transmitted inside the metal tube, there is a disadvantage that the sharpness of the image is inferior and the viewing angle is narrow.

  In the above-mentioned application field, the size of the image sensor application device, for example, a cannula (used in laparoscopic surgery, etc., is used to enter the abdominal cavity because the inspection object is in a narrow space and to ensure minimal invasiveness to the human body. The liquid is an intubation that feeds gas, and an endoscope or a surgical instrument may be inserted into the hollow portion), and the diameter of the “tube” in the stainless circular tube is limited. As a result, there is a limit to increasing the brightness of the optical system or improving the sharpness of the image (in the above example, depending on the total number of glass fibers). On the other hand, along with the recent progress of an aging society, the advancement of medical technology, and the increasing demands for ensuring the safety of factory plants, these image sensor application devices have become more sophisticated, for example, bright, high-resolution, wide-field image information has become stronger. It has been demanded.

  In order to meet such demands, attempts have been made to digitize endoscopes. Specifically, an optical lens and an image sensor are mounted on the distal end (distal end) of the endoscope, and image information is transmitted to the hand (proximal end) of the device using an electrical signal, and the image is displayed on a television monitor. There is an "electronic endoscope" that provides In the following cited Patent Document 1, such a structure of an electronic endoscope is proposed. In Patent Document 2 below, a structure in which an image sensor with a wide field of view is accommodated in parallel with the port tube of the Rapallo port is proposed. Furthermore, the following cited patent document 3 proposes a configuration of an electronic endoscope using near-infrared light for examination of a blood vessel inner wall.

  FIG. 16 is a diagram described in FIG. 1A and FIG. 1A is a cross-sectional view of a laparoscope, 2 is a cannula, 3 is an endoscope inserted into the 2, 1 is a light guide for guiding illumination light, and 31 a is a wide-angle lens for imaging. Details of the tip of the cannula (right end in the figure) are shown in FIG. In the figure, 32 is a connecting cylinder, 31 is an image pickup means, and is composed of the wide-angle lenses 31a and 31b. In such a structure, an image signal converted into an electrical signal by the imaging means attached to the tip of the cannula is displayed on a television monitor (not shown) via the connection cable 34. In the following cited patent document 1, it is said that with this configuration, a clear and fine image can be obtained with a wide field of view as compared with a conventional fiberscope.

  FIG. 17 is a diagram described in FIG. In the figure, reference numeral 100 denotes a Rapallo port (a tube similar to the above-described cannula, which facilitates access between the outside of the body and the abdominal cavity), 11 is a port tube, and an endoscope 14 is inserted into the hollow portion inside. Examples are shown. Reference numeral 13 denotes an image sensor, which can pick up a wide-angle field of view with a lens at the tip. Such a configuration is described as a “wide-angle assist monitor system”. The surgical object can be observed with 14 endoscopes, and the peripheral part of the surgical object can be observed with 13 image sensors. Surgery is possible.

  18 (a) and 18 (b) are diagrams described in FIG. 2 and FIG. 3 of the following cited patent document 3, respectively. In FIG. 9A, 100 is a sectional view of the catheter tip, 108a and 108b are lenses, 112 is a photodetector array, 114 is a semiconductor chip, and 80 is a cable. FIG. 2B conceptually shows the assembly of the photodetector array 112. In the following cited patent document, 112 is composed of a semiconductor such as a Group 3 group 5 compound or InGaAs, and has a near infrared wavelength range of 1.5 to 1.8 micrometers, or 2.1 to 2.3 micrometers. It is preferred to operate. It is also shown that 112 is arranged so that the surface of the array faces the 114 side, and 112 and 114 are coupled by flip chip bonding. Such a configuration is considered suitable for cardiovascular examination. That is, blood is opaque to visible light, but is transparent in the near-infrared wavelength region described above, so that blood vessel walls can be easily observed.

JP 2000-2205090 A JP 2008-6227 A JP 2008-506478 A

  As described above, in Cited Patent Document 1, an example in which a “fiber scope” is computerized is cited. In Cited Patent Document 2, a case of a “wide-angle assist monitor system” combined with an endoscope is cited. Examples of electronic endoscopes in the wavelength range have been proposed. Each case is characterized in that an image is converted into an electric signal by a lens and an image sensor mounted at the tip of the image sensor application apparatus. Such computerization has eliminated the drawbacks of the conventional “fiberscope” such as a narrow field of view, unclear and coarse images, and has made it possible to contribute greatly to the medical equipment field and the industrial measurement field.

However, in the image sensor application apparatus having the above-described configuration, there is a limit of high resolution and high sensitivity due to “mounting a square image sensor in a tube having a circular cross section”. That is, the cross-section of an intracorporeal medical device represented by an endoscope or the like is circular. This is because it is necessary to make a hole of about 5 to 10 millimeters in the abdomen, and thus a circular shape having no protruding portion in the cross-sectional shape is preferable. On the other hand, an image sensor is manufactured using semiconductor technology, and the shape thereof is a square or a rectangle. Such a configuration is also illustrated in a cited drawing from cited Patent Document 3 shown in FIG. As shown in FIG. 1, when a square image sensor is mounted inside a circular tube, it is inevitable that a space exists around the image sensor. The figure schematically shows how various shapes of image sensors are housed in a tube 300 having a circular cross section. 2A shows a square image sensor 301, and FIGS. 2B and 2C show a circular image sensor 302 and a hexagonal image sensor 303, respectively. As shown in FIGS. 3A and 3C, when the image sensor is a polygon including a square, a space may be generated between the outer periphery of the image sensor and the inner wall of the circular tube. Inevitable. For example, when the inner diameter (radius) of the tube is r, the length L1 of one side of the square (301) inscribed in the inner diameter and the area S1 are expressed by the following equations.


The cross-sectional area (S0) of the circular pipe 300 is


Therefore, the area ratio occupied by the image sensor is 2 / π, that is, only 64%. On the other hand, in the case of a regular hexagonal image sensor (303) as shown in FIG.


Thus, the area ratio occupied by the image sensor is 3√3 / 2π, that is, 83%. Furthermore, in the case of a circular image sensor (302) as shown in FIG. 4B, the area ratio occupied by the image sensor is 100%.

  As described in the previous paragraph, when an image sensor is mounted inside a tube having a circular cross section, only 64% of a square and 83% of a regular hexagon can be effectively used with respect to the available cross sectional area. As a result, as described later, the number of pixels that can be integrated in the image sensor is limited, the photosensitivity is limited, and the diameter of the circular tube cannot be reduced. It has become difficult.

  An image sensor application device having an imaging device mounted at the tip of a tube made of metal, or resin, or a combination of metal and resin, and comprising at least a lens, an image sensor, and an image processing IC, The shape of the image sensor is a circle or at least a pentagon.

  Note that the term “IC” in the above-described image processing IC is a semiconductor element in which a large number of transistors and the like are integrated, and is also referred to as VLSI or ULSI depending on the number of integrated transistors. In the present specification, these are included in the term “IC”.

  The tube material may be a metal such as stainless steel or a resin such as ABS or acrylic. Further, a combination of a metal and a resin, for example, a material in which a metal surface is coated with a resin, a material in which a resin surface is coated with a metal, or the like may be used.

  In medical equipment and industrial measuring equipment, the tube often has a circular cross-sectional shape. This is because, for example, in the medical field, when inserting the inspection device into the abdominal cavity, a “cornerless” circular shape or an elliptical shape is preferable from the viewpoint of low invasiveness so as to reduce resistance from the periphery. is there. In the medical field, from the viewpoint of infection prevention and hygiene, it is preferable that the tip portion of the image sensor application device and the outer periphery of the tube are coated with titanium oxide or the like, and has a structure that can withstand sterilization treatment and the like. It is preferable. It is preferable that the tip portion is hydrophilic so that the imaging device at the tip portion of the image sensor application device does not deteriorate the cloudy imaging function due to moisture or the like. In general, it is preferable that the lens has little image distortion and a wide-angle field of view. Such a lens may have a single lens structure, but is not limited thereto. For example, a multi-group multiple lens configuration, a configuration using an aspherical lens, or a fish-eye lens configuration to obtain a wider field of view may be used. The imaging apparatus often has a color imaging function with visible light, but is not limited thereto. For example, it may have a monochrome imaging function with visible light. Furthermore, for example, it may have an imaging function in the near infrared wavelength region of about 1 to 2 micrometers or in the infrared wavelength region. It is preferable that the tip of the image sensor application device has an illumination device composed of an LED or the like for illuminating an object. A plurality of the lighting devices may be arranged along the periphery of the tube so that the object is not shaded, and may be in the form of a ring light.

  The shape of the tube is not limited to a circle but may be an ellipse. Furthermore, only the tip portion where the tube is inserted into the body such as the abdominal cavity may be circular, and the portion exposed to the outside of the body may have a shape other than circular.

  Note that devices other than the imaging device may be disposed inside the cross section of the tube. In a general endoscope, a cavity called a channel is provided in addition to the imaging device. This channel is used, for example, as an insertion path for a surgical instrument such as forceps or a medical solution ejection path such as physiological saline. The cross-sectional shape of the channel is often circular, and the imaging device is arranged in a portion other than the channel portion in the tube. In such a configuration, the tube is eccentrically arranged inside a tube made of metal or the like (for example, a tube of an endoscope main body). Also in this configuration, the shape of the image sensor that is a component of the imaging device can be a circle or a polygon that is a pentagon or more.

  In addition, it is preferable that the image sensor and image processing IC which comprise the said imaging device are laminated structure. By adopting such a laminated structure, it is possible to arrange an electrical connection means to the image sensor in the lamination direction. As a result, it is not necessary to prepare a space for the bonding wire around the image sensor as compared with the electrical connection means using the bonding wire that has been widely used in the past, and it is possible to mount in a small area. Will occur. In such a structure, the outer shape of the image processing IC is preferably similar to that of the image sensor, but is not limited thereto. For example, a rectangular image processing IC may be combined with a circular image sensor. Furthermore, a wiring board may be attached to the image processing. The wiring board may be connected to a wiring that connects the imaging device and the outside of the image sensor application device and transmits desired information. Such a wiring board has a small pattern size (about several tens of micrometers) in a normal semiconductor element, and can be used to convert to a relatively large size (about 1 mm) necessary for connecting the wiring. good. The image sensor often includes a drive circuit and a circuit for processing an output signal. The image processing IC may have functions such as an image signal digital conversion function, an image sharpening function, an image band compression function, and a wireless communication function. Further, active elements such as transistors and passive elements such as capacitance and resistance may be mounted on the wiring board.

  In addition, when the shape of the image sensor is at least a pentagon (that is, a polygon that is a pentagon or more), it is not necessarily a regular polygon.

  The image pickup apparatus includes at least a lens, an image sensor, and an image processing IC, but is not limited to this. For example, when the image sensor is equipped with an image processing function, the image processing IC may be unnecessary. An interposer may be used as an alternative to the image processing IC. In such a case, the interposer may be provided with a “rewiring” function for changing the wiring of the image sensor or changing the wiring pitch.

  Note that it is necessary to cut the image sensor into a single image sensor from a state where a plurality of image sensors are arranged on the wafer. In this cutting-out process, a crack induced by strain generated by melting by laser or local heating by laser may be used. Furthermore, methods such as sand blasting and water jet may be used. In the cutting process, (1) the wafer on which the image sensor is arranged and the wafer on which the image processing IC are arranged are opposed to each other and laminated at the wafer level. (2) From the laminated structure, You may employ | adopt the two steps of cutting out the structure by which one image sensor and single image processing IC were laminated | stacked with the above-mentioned various methods. In such a cutting-out process, a cushion may be attached to the lower surface of the image sensor or the like so that the image sensor or the like separated from the wafer does not dissipate. Furthermore, wet and dry etching may be used for the above-described cutting.

  The image sensor has a region where photosensitive elements are arranged and a region where peripheral circuits such as a drive circuit and a signal processing circuit are arranged. By making the outer shape of the image sensor circular, the number of arranged photosensitive elements can be increased, and the resolution characteristics and the sharpness of the image can be improved. In addition, the area occupied by the photosensitive element can be increased, the photosensitivity characteristics can be improved, and a good image can be obtained even for a dark subject.

  Note that the outer shape of the image sensor can also be a regular hexagonal shape, so that the number of photosensitive elements and the area occupied by the photosensitive elements can be increased as described in the previous paragraph. Further, when the regular hexagonal image sensor is mounted in the tube having a circular cross section, a space is left between the inner wall of the tube and the outer peripheral portion of the image sensor. It can also be used. For example, the wiring to the illumination system may be stored in the space.

  The lens, which is a component of the imaging device, is provided with a reflecting mirror that is disposed obliquely inside the tube and has a mechanism that can rotate around the axis of the tube.

  The reflecting mirror is attached to a rotating part (rotor) of the motor, and a stationary part (stator) of the motor is fixed to the pipe. It is preferable that the rotation center of the rotor coincides with the optical axis of the lens, and further, the optical axis coincides with the center position of the photosensitive element region of the image sensor. Moreover, it is preferable that the reflector has an angle of 45 degrees with respect to the optical axis, but this is not restrictive.

  Note that the reflecting mirror does not always rotate during operation of the image sensor application apparatus. For example, in the process of inserting the image sensor application device into the body, the periphery of the tip portion of the image sensor application device can be observed over 360 degrees by continuously rotating the image sensor application device. Proximity to becomes easier. On the other hand, if the rotation of the reflecting mirror is stopped after approaching the inspection object, only one direction around the tip of the image sensor application apparatus can be observed in detail.

  It is easy to apply the configuration described in the previous paragraph to a “swallow type” image sensor application apparatus. In such an application form, instead of the circular tube described above, a tablet capsule type container having a circular cross section may be used. In this mode, information transmission between the imaging device and the outside of the image sensor application device is preferably performed not via the above-described wiring but via a wireless device arranged close to the imaging device. . In this mode, since the image sensor application apparatus moves the inspection information while moving in the human body, it is preferable that the reflecting mirror is constantly rotating.

  Note that the “swallow-type” image sensor application apparatus described above may be configured such that the imaging device captures only “front” of the image sensor application apparatus without mounting a reflecting mirror. In such a configuration, in order to obtain a wide observation field of view, the lens of the imaging device is preferably a wide-angle lens or a fish-eye lens.

  On the surface of the semiconductor substrate constituting the image sensor having the circular or at least pentagonal shape, 1) a rectangular photosensitive element region in which a plurality of photosensitive elements are arranged, and 2) around the photosensitive element region, An image sensor driving circuit and a peripheral circuit region including a signal processing circuit are arranged, and electrical connection means for transmitting a signal from the image sensor or a signal to the image sensor is provided on the back surface of the semiconductor substrate. Deploy.

  The electrical connection means is used for transmitting an electrical signal between the image sensor and the image processing IC. The electrical connection means may include a through electrode formed from the back surface side of the semiconductor substrate toward the electrode pad disposed on the front surface side of the semiconductor substrate. Further, the electrode pads are not necessarily arranged around the semiconductor substrate. The electrode pads may be arranged in a photosensitive element region or a peripheral circuit region of the image sensor.

  By making the outer shape of the image sensor circular or polygonal, high resolution or high sensitivity can be easily achieved.

For example, when mounting the image sensor in a circular tube with the same inner diameter, compared to the case where the image sensor is a square,
For circular image sensors, the area is 1.57 times larger
In a regular hexagonal image sensor, the area can be increased by 1.21 times. This effect of increasing the area can contribute to (1) an increase in the number of photosensitive elements and (2) an increase in the area of the photosensitive elements. For example, assume two points: (1) the area of the image sensor is represented by the product of the area of the photosensitive element and the number of photosensitive elements, and (2) the sensitivity of the image sensor is proportional to the area of the photosensitive element. Specific numerical examples are given below.
1): In a circular image sensor, the number of photosensitive elements can be increased 1.57 times.
[For example, if it is 300,000 pixels in the past, it will increase to 470,000 pixels]
2): In a regular hexagonal image sensor, the number of photosensitive elements can be increased by 1.21 times.
[For example, if it is 300,000 pixels in the past, increase to 360,000 pixels]
3): In a circular image sensor, the sensitivity can be increased 1.57 times.
[For example, it is possible to capture images with a brightness of 64% of the conventional one]
4): In a regular hexagonal image sensor, the sensitivity can be increased 1.21 times.
[For example, it is possible to capture images at 83% brightness]

Further, as an effect of increasing the area, it is also possible to reduce the diameter of the circular tube on which the image sensor application apparatus is mounted. Specific numerical examples are listed below.
1): In a circular image sensor, the diameter of the circular tube can be reduced to 80%.
[For example, if it was 5 millimeters conventionally, it will be reduced to 4 millimeters]
2): In a regular hexagonal image sensor, the diameter of the circular tube can be reduced to 90%.
[For example, if it was 5 millimeters conventionally, it will be reduced to 4.5 millimeters]
As shown in this specific example, in an application field that is assumed to be inserted into the body, a great effect can be obtained from the viewpoint of minimally invasiveness.

  The image sensor application device is provided by providing a reflecting mirror having a mechanism that is disposed obliquely inside the tube and that can rotate around the axis of the tube on a lens that is a component of the imaging device. It becomes possible to observe the periphery of the tip of the lens over 360 degrees. This mechanism makes it safe and easy to guide the image sensor application apparatus to the inspection target. After approaching the inspection object, the rotation of the reflecting mirror can be stopped, and only one direction around the tip of the image sensor application apparatus can be observed in detail. In addition, the location of the inspection object can be changed by rotating the reflecting mirror by a minute amount.

  In the configuration according to the present invention, the area occupied by the image sensor can be made the same (or substantially the same) as the cross-sectional area of the circular metal tube. The image sensor application apparatus can be downsized, and the effect of the present invention can be said to be great.

It is a figure explaining the shape of the image sensor mounted inside the circular pipe | tube. It is a figure which shows the structure of an image sensor application apparatus. <Example 1> [Image sensor application apparatus-1 equipped with a circular sensor] It is a figure which shows the structure of an image sensor application apparatus. <Example 2> [Image sensor application device equipped with a hexagonal sensor] It is a figure which shows the structure of an image sensor. <Example 3> It is a figure which shows shapes, such as an image sensor. <Example 4> It is a figure which shows the arrangement | sequence form of an image sensor etc. in a wafer. <Example 5> It is a figure which shows the method of cutting out an image sensor from a wafer. [Method 1 for Cutting Image Sensor from Wafer-1] <Example 6> It is a figure which shows the method of cutting out an image sensor from a wafer. [Method 2 for Cutting Image Sensor from Wafer] <Example 7> It is a figure which shows the method of cutting out an image sensor from a wafer. [Method 3 for Cutting Image Sensor from Wafer] <Example 8> It is a figure which shows the method of cutting out an image sensor from a wafer. [Method 4 for Cutting Image Sensor from Wafer] <Example 9> It is a figure which shows the layout of a circular shape image sensor. <Example 10> It is a figure which shows the layout of a hexagonal shape image sensor. <Example 11> It is a figure which shows the cross section of an image sensor application apparatus. [Structure in which a channel is provided in the pipe] <Example 12> It is a figure which shows the structure of an image sensor application apparatus. <Example 13> [Image sensor application apparatus-2 equipped with a circular sensor] It is the figure which showed notionally the rotation mechanism in Example 13. FIG. It is a structure sectional view of a laparoscope. <Conventional example> It is a structure sectional view of a Rapallo port. <Conventional example> It is the figure which mounted the photodetector array in the catheter front-end | tip. <Conventional example>

  Hereinafter, an image sensor application apparatus according to the present invention shown in the drawings will be described in detail.

<Image sensor application device-1 equipped with a circular sensor>
FIG. 2 is a diagram showing a configuration of an image sensor application apparatus according to the first embodiment of the present invention, in which a circular image sensor is mounted at the front end of the apparatus. FIG. 4A is a conceptual diagram showing the configuration of the tip of the apparatus, and FIG. 4B is a sectional view thereof. In this figure, 310 is a tube (for example, a cannula or catheter) made of metal or resin having a circular cross section, 311 is a transparent protective plate provided with a tip of 310, and a peripheral portion for illumination. A plurality of light sources 312 are arranged. A light-emitting diode (LED) or the like is used as the light source. By arranging the light-emitting diodes on the circumference, a so-called ring light can be formed, and an image can be taken without shadowing the subject. It is preferable for hygiene that the surface of the tube made of metal or the like and the surface of the transparent protective plate are flat and the surface is coated with titanium oxide or the like. In particular, the surface of the protective plate 311 is hydrophilic and is preferably surface-treated so that the surface is not clouded by the humidity contained in the atmosphere to be inspected. Further, in order to repeatedly use the image sensor application apparatus for a plurality of operations, it is necessary that at least the distal end portion of the image sensor application apparatus be configured to withstand sterilization treatment. In FIG. 2, 313 is a lens, 314 is a circular image sensor, 315 is an image processing IC for processing a signal from the image sensor, 316 is a wiring board composed of a printed circuit board, and 317 is the metal tube. Wiring is arranged inside to supply an electrical signal from 316 to the outside of the device. The said 313 to the said 316 comprises the imaging device 318. FIG. FIG. 5B shows a case where 313, 314, and 315 are stacked and integrated. Although the case where the lens 313 has a single lens structure is shown, in general, a plurality of lenses may be configured in multiple groups in order to reduce image distortion and allow light from the subject to pass through without decreasing. Many. The 313 is preferably a wide-angle lens, and may be a fish-eye lens. Furthermore, an aspheric lens may be used to reduce the size of the device. Although not shown, the lens may include an autofocus mechanism. The image sensor 313 not only picks up visible light, but also selects the material and configuration of the image sensor so that it can pick up images in the near-infrared wavelength range of 1 to 2 micrometers or in the infrared wavelength range of 3 micrometers or more. You can do it.

  In the first embodiment shown in FIG. 2, a circular metal tube is inserted into the body or factory piping, the inspection object is irradiated by the light source 312, and the light reflected from the inspection object is reflected on the surface of the image sensor 314 by the lens 313. Is imaged and photoelectrically converted. The photoelectrically converted image signal is processed by the image processing IC 315 and guided to the outside of the image sensor application apparatus via the wiring board 316 and the wiring 317. Although the image processing IC 315 may not necessarily be required, it is preferable to employ an image processing IC in order to reduce the number of wirings 317 because the metal tube is thin. In general, the image sensor 313 often integrates a circuit for driving the sensor and a preprocessing circuit such as waveform shaping, amplification, and temperature compensation for photoelectrically converted electric signals. However, these circuits may not be integrated into 314 but may be integrated into 315.

  In the first embodiment described above, the cross-sectional shape of the metal tube 310 is “circular”, but the shape is not limited thereto. For example, it may be oval. Further, only the part where the metal tube is inserted into the body or the pipe may have a circular or elliptical cross-sectional shape, and other shapes (for example, polygons) other than the part may be used.

<Image sensor application device with hexagonal sensor>
FIG. 3 is a diagram showing a configuration of an image sensor application apparatus according to the second embodiment of the present invention, in which a hexagonal image sensor is mounted at the tip of the apparatus. FIG. 4A is a conceptual diagram showing the configuration of the tip of the apparatus, and FIG. 4B is a sectional view thereof. In the figure, the same reference numerals as those in FIG. 2 denote the same components. In the figure, reference numeral 324 denotes a hexagonal image sensor, and reference numeral 325 denotes an image processing IC. The second embodiment is similar to the first embodiment, and is characterized in that the shapes of the image sensor and the image processing IC are different. In the second embodiment, a hexagonal image sensor is illustrated, but the image sensor is not limited to a hexagon and may be a polygon such as an octagon. The polygon including the hexagon is preferably a regular polygon in which the length of each side is equal to the interior angle of each vertex, but is not limited thereto.

<Configuration of image sensor>
FIG. 4 is a third embodiment of the present invention and shows the configuration of an image sensor, an image processing IC, a wiring board, and the like. FIG. 4A shows an image sensor (342), FIG. 2B shows an image processing IC (350), and FIG. 3C shows a wiring board (360). In FIG. 3A, reference numeral 330 denotes a sensor portion made by semiconductor technology, and a plurality of photosensitive elements (photodiodes) 332 are arranged on the surface side of a semiconductor substrate 331 such as Si. Reference numeral 333 denotes an insulating layer in which a plurality of wiring layers for driving an image sensor and transmitting a signal from the photosensitive element are arranged. Reference numeral 334 denotes a color filter arranged for each photosensitive element, and the light transmission characteristics are different for each photosensitive element. For example, “Red” is transmitted to one selected photosensitive element, “Blue” is transmitted to another photosensitive element adjacent to the right side, and “Photosensitive” is adjacent to the other photosensitive element adjacent to the left side. Is set to transmit “green”. With this configuration, it is possible to detect a color image with a single image sensor. In the above example, the case of the three primary color configuration of light is shown, but the transmission characteristics and arrangement of the color filter are not limited to this, and other configurations may be used. For example, a complementary color filter configuration that allows the complementary color of light to pass through or an increase in the number of green color filters can be cited. Reference numeral 335 denotes a microlens arranged for each photosensitive element, and has a function of efficiently guiding incident light to the photosensitive element. Reference numeral 336 denotes an electrode pad provided in the insulating layer. In the configuration example of FIG. 4A, a through hole is formed from the back side of the semiconductor substrate 331 toward the electrode pad, and a through electrode 337 is embedded therein. Reference numeral 338 denotes a wiring pattern electrically connected to the through electrode, and is disposed on the back side surface of the semiconductor substrate 331. Reference numeral 339 denotes a hemispherical ball grid array that is electrically connected to the wiring pattern 338. With this configuration, electrical connection to the image sensor can be made from the back side of the semiconductor substrate via 336 to 339. Reference numeral 340 denotes a cover glass for protecting the sensor, which is disposed on the upper portion of the sensor portion 330 via an adhesive layer 341. As described above, the sensor portion 330, the adhesive layer 341, and the cover glass 340 constitute the image sensor 342.

  In the configuration described in the previous paragraph, all the electrical connections of the image sensor can be performed from the back side of the image sensor. In general semiconductor integrated circuits that are widely used at present, electrical connection to the outside is often made from the surface side of a semiconductor substrate by a thin metal wire called “bonding wire”. Also in the third embodiment, it is possible to perform such “electrical connection from the front side”. In such a case, one end of the thin metal wire is connected to the electrode pad of FIG. 4A, and the other end is connected to a package or a printed circuit board (both not shown). However, in the “electric connection from the front side”, a space for arranging the fine metal wires is required around the image sensor. On the other hand, in the configuration shown in FIG. 4A, that is, “electrical connection from the back side”, the above-described space is unnecessary, and mounting is possible with the same size as the area of the image sensor. In the application field assumed by the present invention, it is strongly required to reduce the area required by the image sensor as much as possible and to reduce the size and diameter of the image sensor application device. Is very effective.

  In FIG. 4, the electrode pad 336 can be wire-bonded (spatial position, material in the layer, material, etc.) so that it is easy to explain the “electric connection from the surface side by the bonding wire” in the previous section. It is shown as if it were a size. However, the electrode pad 336 is not limited to the configuration, and may be any electrical connection with the through electrode 337. For example, in the electrical connection using the bonding wire, the size of the electrode pad needs to be about 100 micrometers, but the size of the electrode pad to which the through electrode can be connected is about 10 micrometers or less. Further, in the case of electrical connection using bonding wires, the electrode pads are often arranged at the periphery of a semiconductor substrate constituting the image sensor. If the electrode pad corresponds to the signal of the central part of the semiconductor substrate, the electrode pad is connected by a long distance wiring from the central part to the peripheral part. However, in the electrical connection by the through electrode, the position of the electrode pad is not limited to this, and can be arranged at an appropriate place in the pattern layout of the image sensor. That is, the electrode pad can be disposed in the central portion of the semiconductor substrate. In addition, in order to increase the processing speed of the image sensor, when parallel signal processing is employed, the output of the image sensor is extracted from a plurality of locations. In such a configuration, a signal is output through a plurality of electrode pads (a part of which is arranged in the central portion) arranged in the image sensor. Thus, the configuration of the electrode pad is a design item when designing the image sensor.

  In FIG. 4B, 350 is an image processing IC. In the figure, components such as transistors are not shown. In FIG. 2B, reference numeral 352 denotes a semiconductor substrate made of Si or the like, and electrode pads 351 are arranged on the surface side (the upper side in the figure). A wiring layer for driving the image processing IC is provided inside 350, and an electrode pad 356 is included in a part thereof. The electrode pad is connected with a through electrode 357, a wiring pattern 358, and a ball grid array 359 for electrical connection as described in detail in FIG. In such a configuration, the above-described ball grid array 339 of the image sensor 342 is connected to the electrode pads 351 of the image processing IC arranged to face each other. As a result, the signal to the image sensor and the signal from the image sensor are combined with the image processing IC. Such a configuration can be said to be a form of a three-dimensional IC.

FIG. 4C shows the configuration of the wiring board 360. In FIG. 6C, reference numeral 366 denotes an electrode pad provided on the surface side (upper side in the drawing) of the wiring board, and is connected to the wiring pattern 368 through the through electrode 367. Such a configuration is realized by performing known processing on a printed circuit board or the like. The electrode pads 366 on the wiring board 360 are connected to the ball grid array 359 of the image processing IC arranged in opposition. As a result, the signal to the image processing IC and the signal from the image processing IC are combined with the wiring board 360. Furthermore, the wiring pattern provided on the back side (the lower side in the figure) of the wiring board 360 includes:
A wiring for supplying an electric signal from 360 to the outside of the device (not shown in the figure, but corresponding to 317 in FIG. 2) is connected.

  Since the image sensor 342, the image processing IC 350, and the wiring board 360 shown in FIGS. 4A to 4C are stacked in the vertical direction, the area occupied by the image sensor is the same as that of the image sensor 342. Become. In FIG. 4B, 350 is described as the image processing IC, but the present invention is not limited to this. For example, 350 may include a drive circuit for the image sensor 342, and a plurality of circuits that shape, amplify, and correct temperature characteristics of the electrical signal from the 342. The function of the wiring board 360 is to draw out electrical signals from 342 and 350 to the outside of the image sensor application apparatus. In general, the pitch of a wiring pattern in a semiconductor integrated circuit is small, about several tens of micrometers, and is too small to directly connect the wiring (corresponding to 317 in FIG. 2). For this reason, the connection of the said wiring becomes easy by passing through a printed circuit board (wiring pitch is several hundred micrometers to millimeters). Judging from this situation, 360 may not be necessary. For example, when the pitch of the wiring pattern 358 on the back side of 350 can be set sufficiently large and the wiring can be directly connected to the wiring pattern, 360 is not necessary. .

  Furthermore, when a drive circuit, a signal processing circuit, an image processing circuit, and the like are integrated in the image sensor 342, the image processing IC in FIG. 4C is not necessarily required. In such a case, the image sensor 342 may be directly connected to the wiring board 360. Further, as an alternative to the image processing IC, the interposer may be replaced with 350. The interposer has a function of facilitating the removal of the wiring by changing the arrangement order of the ball grid array 339 of the image sensor, for example, or converting it to a wiring pattern having a wider pitch. It is a structure. When such an interposer is employed, it is not always necessary to integrate active elements such as transistors in the interposer, and only a conductive pattern may be included.

  In the third embodiment, a case where the wiring board 360 includes only a conductive pattern is shown. However, the wiring board 360 may be equipped with a small-scale active element such as an IC or a transistor, a capacitance element for removing noise, or the like. Such a configuration is the same as that of a general printed circuit board.

  The image sensor shown in FIG. 4A is configured such that light enters from the surface side (upper side in the drawing) of the semiconductor substrate 331 provided with the photosensitive element. As a configuration of the image sensor, there is a “back-side incident type sensor” that makes light incident from the back side of the semiconductor substrate. In the third embodiment, the image sensor having such a configuration may be used. Moreover, as a photosensitive element, you may employ | adopt the structure which has a sensitivity with respect to near infrared rays or infrared rays besides the case where photoelectric conversion of visible light is carried out.

  In this paragraph, a method of combining the image sensor 342 and the image processing IC 350 shown in FIGS. 4A to 4B will be described. As described above, this bonding is achieved by processing the ball grid array 339 and the electrode pad 351 relative to each other and then processing in a high-temperature atmosphere (in some cases, pressure may be applied from above). Such a combination method is not limited to combining the single image sensor and the single image processing IC shown in FIG. In consideration of ease of manufacturing and cost, it is possible to combine at the “wafer level” and then divide the wafer into a single image sensor and image processing IC. More specifically, a wafer in which a large number of image sensors are arrayed and a wafer in which a large number of image processing ICs are arrayed are combined, and thereafter, a process called scribing is performed to overlap two sheets. Divide the wafer. This is an effective manufacturing method when the size of the image sensor matches the size of the image processing IC. However, since the two do not always match, there is a limit to the application of such a coupling method. Of course, if they do not match, “wafer / chip level” (for example, a single image processing IC is coupled to the back side of the wafer on which the image sensor is arranged) or “chip level” ( A single image sensor and a single image processing IC are separately created and combined with each other).

<Shapes such as image sensors>
FIG. 5 shows a fourth embodiment of the present invention, in which combinations of various shapes are shown.
FIG. 5A shows a case where the image sensor 370, the image processing IC 371, and the wiring board 372 are all circular and have the same size.
FIG. 5B shows a case where the image sensor 374, the image processing IC 375, and the wiring board 376 are all hexagonal and have the same size.
(C): Image sensor 378 has a circular shape, image processing IC 379 and wiring board 380 have a rectangular shape, and the area of the image sensor is large.
FIG. 4D shows a case where the image sensor 382 has a hexagonal shape, the image processing IC 383 and the wiring board 384 have a rectangular shape, and the area of the image sensor is large.
Note that a combination of shapes other than those illustrated in FIG. In general, an image sensor tends to have a large area in order to realize high photosensitivity and high resolution characteristics. On the other hand, image processing ICs tend to be easily reduced in area with the miniaturization of semiconductor technology. When a general-purpose image processing IC is used, the shape is often rectangular. Furthermore, the wiring board is easier to manufacture if the shape is rectangular. In view of such a situation, it is not necessary to limit the shapes of the image sensor, the image processing IC, and the wiring board to prescribed shapes (for example, all circular shapes), and many combinations are included in the fourth embodiment. become.

<Arrangement form of image sensors etc. in wafer>
FIG. 6 shows a fifth embodiment of the present invention, which shows that the arrangement state in the wafer (indicated by 400) differs depending on the shape of the image sensor. FIG. 6A is a cross-sectional view of a structure 390 in which three image sensors are arranged side by side, and a dashed line 391 indicates the boundary between the image sensors. Note that the configuration of a single image sensor constituting 390 is the same as that of 342 in FIG.
FIG. 6B shows an arrangement state when the shape of the image sensor is a rectangle (401).
FIG. 6C shows an arrangement state when the shape of the image sensor is a regular hexagon (402).
FIG. 6D shows an arrangement state when the shape of the image sensor is a circle (403).
In FIG. 6B, since the image sensors are arranged in alignment, the image sensors can be cut in the vertical and horizontal directions along the peripheral edge of the image sensor. This arrangement is the same as that of a normal semiconductor integrated circuit. In FIG. 6C, regular hexagonal image sensors are closely arranged in a “honeycomb shape”, and no useless space is generated between the image sensors. On the other hand, in the case of the circular image sensor as shown in FIG. 4D, the image sensors can be arranged so as to contact each other at one end of the circumference, but a wasteful space is generated between the image sensors. Become. The existence of such a space is not preferable from the viewpoint of semiconductor manufacturing because it reduces the number of image sensors that can be arranged per wafer. However, in the present invention, “arranging the circular image sensor inside the circular tube” has many advantages, and thus it can be said that such a useless space can be allowed to exist. Further, in the case of FIG. 6C and FIG. 6D, the conventional simple division method described with reference to FIG. 5B cannot be employed to divide the wafer and cut out a large number of image sensors. .

<Method for cutting out image sensor from wafer-1>
FIG. 7 is a diagram for explaining a method of cutting out a regular hexagonal or circular image sensor from one wafer according to a sixth embodiment of the present invention. FIG. 4A shows a case where a hexagonal image sensor is cut out. In the figure, reference numeral 400 denotes a wafer on which a large number of image sensors (402) are arranged in a honeycomb shape, and reference numerals 410 to 413 denote laser beam trajectories used for cutting. The laser is an infrared laser and is driven by a dedicated device that can control the beam position. In addition, the dedicated device includes a mechanism that shields the laser with a shutter or the like. By this mechanism, the laser light is turned on (a state in which the laser light is irradiated) and in an off state (the laser light is cut off). (Status) can be set. When the laser beam is applied to the wafer surface in the on state, local heat generation occurs, and the portion melts and a hole is formed by evaporation. When the laser beam is moved in this ON state, a cutting groove is formed. The laser beam is moved (scanned) along the locus 410 in FIG. 7A, and the thick solid line portion is set to the on state and the thick broken line portion is set to the off state. When the scanning along the trajectory 410 is completed, the same scanning is performed along the trajectory 411. This scanning is repeated in the oblique directions 410 and 411. When the scan in the oblique direction is completed over the entire surface of the wafer 400, the direction of the laser beam trajectory is tilted 60 degrees to the right, and the same scan is repeated along the trajectory 412. Subsequently, the same scanning is repeated along the locus 413. Thus, a single image sensor (402) is cut out from the wafer 400 by scanning in which the ON state and the OFF state are intermittently repeated in three different directions. Through the above steps, a regular hexagonal image sensor can be easily manufactured.

  FIG. 7B shows a case where a circular image sensor is cut out. In the figure, reference numeral 400 denotes a wafer on which a large number of image sensors (403) are arranged adjacent to each other, and reference numeral 415 denotes a locus of laser light used for cutting. In FIG. 6B, it is possible to cut out a single image sensor 403 from the wafer 400 by scanning in a circle along the periphery of the image sensor with the laser light turned on, and repeating this scanning. is there.

  In the previous paragraph, a method for melting and evaporating a part of a wafer by laser light irradiation was described. However, when the wafer is melted, a part of the wafer that has become liquid may scatter to the periphery during evaporation and adhere to the surface of the image sensor. When this adhesion occurs, a part of the image sensor blocks the incident light, which may make the sensor defective. In order to prevent this, a laser cutting technique called “stealth dicing” has recently been developed. This technique utilizes the fact that an infrared laser is focused inside a wafer, a large strain is generated inside, and this strain induces a “break” that reaches the surface from the inside. Due to the generation of the tear, a single image sensor can be separated from the wafer by applying an impact force to the wafer. Such stealth dicing may be used to cut out the image sensor shown in FIGS. 7A and 10B.

<Method-2 for cutting out image sensor from wafer-2>
FIG. 8 is a diagram for explaining another method of cutting out a circular image sensor from one wafer, which is Embodiment 7 of the present invention. The seventh embodiment is characterized in that sand blasting is used. In FIG. 8A, 420 is a wafer, 421 is a circular image sensor, and a plurality of image sensors are arranged. A cross-sectional view taken along one-dot chain line 422 is shown in FIG. In FIG. 4B, reference numeral 423 denotes an image sensor, and a case where three image sensors are arranged in the horizontal direction is shown. Reference numeral 424 denotes a line indicating the boundary of each image sensor. Reference numeral 425 denotes a sandblast mask layer, which is laminated only on a portion that is not removed in this process (an area in the wafer where an image sensor is present). Reference numeral 426 indicates the flow of abrasive grains in sandblasting. Hereinafter, a method for forming the mask layer 425 will be described.
(1) A sheet-like dry film is stuck on the wafer. As a material for the mask layer
Is often a photosensitive urethane resin.
(2) Using a well-known exposure technique, irradiate the region where the image sensor exists with ultraviolet rays.
When the dry film is a negative type, the image sensor is obtained by this exposure.
The composition of the region where there is is changed.
(3) The dry film in the region not irradiated with ultraviolet rays is melted and removed by the developer.
It is. As a result, as shown in FIG.
The film remains and becomes a mask layer.
(4) The remaining dry film is baked.
(5) High-speed abrasive grains collide with sandblasting to physically remove areas other than the mask layer
To do.
(6) The dry film is peeled off from the mask layer, and the image sensor is cleaned.
Since the dry film serving as the mask layer is soft, even if abrasive grains collide, the impact force can be absorbed. On the other hand, since the region not covered with the mask layer is made of a hard material such as a protective glass, an adhesive layer, or a semiconductor, it is destroyed by an impact force due to collision of abrasive grains. The size of the abrasive grains may be selected as appropriate, but when processing is performed on a fine area, a small-diameter abrasive grain is selected. In sandblasting, it is known that if the processing area is extremely small, the abrasive grains are buried in the object and the processing does not proceed. As an example, a processing area of about 50 micrometers is said to be the limit. For this reason, in the arrangement of the image sensors in FIG. 8A, the interval needs to be 50 micrometers or more. When this interval is large, abrasive grains having a large diameter can be used, and there is an advantage that the processing time can be shortened.

  FIG. 8 illustrates a case where the image sensor has a circular shape. However, the seventh embodiment is not limited to this, but can be applied to shapes other than circular shapes, for example, hexagonal and octagonal image sensors. In addition, in the figure, it is shown that abrasive grains collide from the front side (upper side in the figure) of the image sensor, but a mask layer is provided on the back side (lower side in the figure) of the image sensor, and the back side The abrasive grains may collide with each other. In the formation of the mask layer in the previous paragraph, a method of forming a pattern on a sheet-like dry film is exemplified, but not limited thereto. For example, a single dry film may be exposed, developed, and baked to create a circular dry film in advance, and a plurality of the circular dry films may be attached to the wafer. Further, in FIG. 8B, a seat (not shown) serving as a cushion may be attached to the lower side of the image sensor. In this case, the cushion has an advantage that the individual image sensors can be prevented from being scattered apart at the stage where the sandblasting is completed and the individual circular image sensors are created. The cushion may be laminated and optionally spin coated. The cushion may be a dicing sheet used in a scribe (chip separation) process of a semiconductor manufacturing process. In addition, in Example 7 of FIG. 8, the case where “sand blast” is used is described, but “water jet” technology in which high-pressure water is collided with an object to be processed can also be used.

<Method 3 for cutting out image sensor from wafer-3>
FIG. 9 shows an eighth embodiment of the present invention, and is a diagram for explaining another method for cutting out a circular image sensor from one wafer. In Example 8 as well, an example using sandblasting is described. As shown in FIG. 9, the eighth embodiment is different from the seventh embodiment in that the image sensor (displayed as 423) and the image processing IC (displayed as 350) are stacked at the wafer level. It is characterized by sandblasting 430. In FIG. 9, an alternate long and short dash line 431 indicates a boundary of a single image sensor in the wafer, and the image sensor and the image processing IC are separated from the wafer along the chain line. In Example 7 described above, the image sensor and the image processing IC are obtained by sandblasting each of the wafers on which the image sensor and the image processing IC are arranged individually, and separating the single image sensor and the single image processing IC from the wafer. Need to be laminated. On the other hand, in the eighth embodiment, since the structure 430 is configured at the wafer level and then the wafer is cut, the manufacturing process is simplified, and the manufacturing technique is more preferable than the seventh embodiment. I can say that. Although not described in this paragraph, as described in Example 7, many modifications are included such as application to a hexagonal shape, sandblasting from the back side, and attachment of a cushion.

<Method 4 for cutting out image sensor from wafer-4>
FIG. 10 is a diagram for explaining another method of cutting out a circular image sensor from one wafer according to the ninth embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 8 denote the same components. FIG. 4B is a structural cross-sectional view of the portion indicated by the alternate long and short dash line 422 in FIG. In FIG. 4B, reference numeral 441 denotes a sensor portion (corresponding to 330 in FIG. 4A) constituting the image sensor, and has a structure in which a microlens is exposed on the surface side. An alternate long and short dash line 442 is a boundary of a single sensor portion. Reference numeral 443 denotes a resist layer disposed on the 441. Such a resist layer is formed by a known exposure technique. Reference numeral 444 denotes a flow of a solution or gas for etching (etching) a region where the 443 does not exist. Such etching includes a wet method using a solution and a dry method using a gas. Many solutions can be used in the wet process. For example, hydrofluoric acid solution for silicon oxide, nitric hydrofluoric acid solution for silicon, EDP (ethylenediamine pyrocatechol), KOH (potassium hydroxide), hydrazine, TMA (trimethylaluminum), etc. . In the dry method, there is an ion etching method using fluorine-based gas ions. By this etching, the wafer region not covered with the resist layer 443 can be removed, and a single sensor portion can be cut out. In this etching, since the etching proceeds along the thickness direction of the wafer, when the etching depth increases, the etching proceeds in the lateral direction, which is different from the shape of the resist layer 443 (generally, more The area tends to become smaller. When such a shape change is not preferable, it is preferable to employ “anisotropic etching” in which etching proceeds only in the thickness direction of the wafer.

  Up to the previous paragraph, various methods for cutting out image sensors from wafers have been described. In either method, the final shape image sensor is cut out from the wafer. However, the present invention is not limited to such a method, and includes “cutting out an image sensor having a halfway shape from a wafer and processing the single image sensor into a final shape”. One example is to cut out a “rectangular” region that contains (preferably circumscribing) the image sensor from the wafer, and then processing from the separated rectangle to a final shape (eg, circular or polygonal). This method has an advantage that a scribe used in a normal semiconductor manufacturing process can be used for cutting into a rectangle.

  In addition, as described in the previous paragraph, various methods for cutting out an image sensor from a wafer can be applied to shapes other than hexagons and circles, for example, polygons of pentagons or more. it is obvious.

<Layout of circular image sensor>
FIG. 11 is a tenth embodiment of the present invention and shows a layout on the surface of a circular image sensor. FIG. 4A shows a conventional example, and reference numeral 451 denotes a square-shaped image sensor arranged along the inner wall 450 of the circular tube. On the surface thereof, a region where photosensitive elements are arranged (hereinafter referred to as “photosensitive”). An element region “display” 452 and a peripheral circuit region (hereinafter referred to as “peripheral circuit region”) 453 in which drive circuits and signal processing circuits are arranged are arranged. FIG. 5B shows a situation where a circular image sensor 461 is arranged along the inner wall 450. Reference numeral 462 denotes a photosensitive element region, and 463 denotes a peripheral circuit region. In FIG. 5B, photosensitive elements having the same size as the photosensitive elements in FIG. 5A are arranged, but the number thereof is large. For example, compared with 36 elements in FIG. 11A, the number of elements is 81 in FIG. 11B, which is increased by 2.25 times. That is, by changing the image sensor from a square to a circle, the number of photosensitive elements can be increased, the resolution characteristics of the image sensor can be easily improved, and the image can be sharpened.

  FIG. 6C shows a situation where a circular image sensor 471 is arranged along the inner wall 450. Reference numeral 472 denotes a photosensitive element region, and 473 denotes a peripheral circuit region. In FIG. 8C, the same number of photosensitive elements as the photosensitive elements in FIG. 9A are arranged, but the area (so-called “pixel area”) is large. For example, the photosensitive element area is 2.25 times that of the photosensitive element in FIG. In general, it is known that in an image sensor, when the area of a photosensitive element (pixel) serving as a unit is increased, light sensitivity is increased, and even a low-illumination subject can be imaged. That is, by changing the image sensor from a square to a circle, the area of the photosensitive element can be increased, and the photosensitivity characteristics of the image sensor can be easily improved.

  FIG. 4D shows a situation where a circular image sensor 481 is arranged along the inner wall 450. This figure shows a case where there is no peripheral circuit area and all the area is allocated to the photosensitive element area 482. Such a configuration depends on the operation principle of the image sensor and the drive / signal processing method, but can be realized by assigning a drive / signal processing circuit to the image processing IC described above. In FIG. 9D, photosensitive elements having the same size as the photosensitive elements in FIG. 9A are arranged, but the number thereof is large. For example, in contrast to 36 elements in FIG. 10A, there are 128 elements in FIG. Of course, it is possible to increase the number of photosensitive elements in the square to about 100 by eliminating the peripheral circuit region 453 in FIG. In any case, the number of photosensitive elements can be easily increased by changing the outer shape of the image sensor from a square to a circle.

  As described in the previous paragraph, it is possible to increase the area of the image sensor by changing the image sensor from a square to a circle, and this increase in the area increases the number of photosensitive elements and the area of the photosensitive elements. Can be used. As a result, it can be expected that the resolution characteristics and photosensitivity characteristics of the image sensor will be greatly improved, and the effects of the present invention will be great.

<Hexagonal shape image sensor layout>
FIG. 12 shows a layout on the surface of the hexagonal image sensor, which is Embodiment 11 of the present invention. In the figure, the same reference numerals as those in FIG. 11 denote the same components. FIG. 6A shows a conventional example, and shows a square-shaped image sensor 451 arranged along the inner wall 450 of the circular tube. FIG. 5B shows a situation where a hexagonal image sensor 491 is arranged along the inner wall 450. Reference numeral 492 denotes a photosensitive element region, and 493 denotes a peripheral circuit region. In FIG. 5B, photosensitive elements having the same size as the photosensitive elements in FIG. 5A are arranged, but the number thereof is large. For example, compared with 36 elements in FIG. 6A, 64 elements in FIG. 5B, which is increased 1.78 times. That is, by changing the image sensor from a square to a hexagon, the number of photosensitive elements can be increased, the resolution characteristics of the image sensor can be easily improved, and the image can be sharpened. Further, as described in Example 10, it is possible to increase the area of the photosensitive element by using the same number of photosensitive elements. Further, the same effect can be obtained even if the outer shape of the image sensor is not a hexagon but a polygon including an octagon. In FIG. 12B, it is inevitable that a space is generated between the image sensor 491 and the inner wall 450. The space does not become a useless area and can be used for other purposes. For example, it can be used for the wiring 494 for supplying power to the illumination light source (312 in FIG. 2) composed of the above-described LEDs.

  As described in the previous paragraph, it is possible to increase the area of the image sensor by changing the image sensor from a square to a hexagon, and this increase in area increases the number of photosensitive elements and the area of the photosensitive elements. Can be used. As a result, it can be expected that the resolution characteristics and photosensitivity characteristics of the image sensor will be greatly improved, and the effects of the present invention will be great.

  In Example 10 and Example 11 described in detail with reference to FIGS. 11 and 12, the signals of the image sensor are electrically connected from the back side of the image sensor. That is, in these embodiments, the electrical connection is not realized from the surface side of the image sensor. As described in FIG. 4, this electrical connection means is realized by “a through electrode from the back surface of the substrate” or the like.

  Further, as an effect of adopting the above-described circular or at least pentagonal image sensor, it is possible to reduce the diameter of the circular tube of the image sensor application apparatus. That is, the diameter of the circular pipe can be reduced by employing a circular pipe having an area equal to the square area inscribed in the circular pipe wall inside the circular pipe. To describe in more detail, assuming a circular image sensor having an area equal to the area of the square image sensor inscribed in the circular tube wall (that is, the same imaging function as that of the square image sensor can be realized). The diameter of the circular tube that can accommodate the circular image sensor can be reduced. For example, in a circular image sensor, the diameter of the circular tube can be reduced to 80%. Specifically, if the outer diameter of the image sensor application device is 5 mm in the past, the outer diameter can be reduced to 4 mm by the reduction. In application fields that are supposed to be inserted into the body, this can be said to be a great effect from the viewpoint of minimally invasiveness. The same effect can be obtained when the image sensor is polygonal.

<Structure with channels in the pipe>
FIG. 13 shows a twelfth embodiment of the present invention and shows that an image pickup device and other devices are housed inside the image sensor application device. In the figure, reference numeral 500 denotes a pipe made of metal or the like constituting the outer wall of the image sensor application apparatus, and 501 denotes a cavity called a channel disposed inside the image sensor application apparatus. In a general endoscope, a cavity called a channel is provided in addition to the imaging device. This channel is often used, for example, as an insertion path for surgical instruments such as forceps or a medical solution ejection path such as physiological saline. The number of channels is not limited to one, but may be a plurality of channels having different sizes. The cross-sectional shape of this channel is often circular. In the figure, a tube 502 housing an imaging device is arranged in a portion other than the channel portion in the tube. In such a configuration, the tube 502 is arranged eccentrically inside a tube 500 made of metal or the like (for example, a tube of an endoscope main body). Even in such a configuration, many advantages described in the present specification are generated by making the shape of the image sensor, which is a component of the imaging device, circular or a polygon of pentagon or more.

<Image sensor application device-2 equipped with a circular sensor>
FIG. 14 is a view showing another configuration of the image sensor application apparatus according to the thirteenth embodiment of the present invention, in which a circular image sensor is mounted at the tip of the apparatus. This embodiment is characterized in that a rotating mirror is provided on a lens that is a component of the imaging apparatus. In the figure, the same reference numerals as those in FIG. 2 denote the same components. Unlike FIG. 2, this figure is drawn on the assumption that the object detected by the image sensor exists in the horizontal direction, not in front of the apparatus. FIG. 4A is a conceptual diagram showing the configuration of the tip of the apparatus, and FIG. 4B is a sectional view thereof. In the figure, reference numeral 510 denotes a cylindrical window that corresponds to a part of the metal tube 310 having a circular cross section and is made of a material that is transparent to the light to be detected. Reference numeral 511 denotes a protective plate positioned at the tip of 310, which is made of a material that is opaque to the light. Reference numeral 515 denotes a reflecting mirror provided in front of the lens, which is disposed obliquely inside the circular metal tube and driven by a rotating mechanism. Such rotation is indicated at 516.

  FIG. 15 is a diagram conceptually showing the rotation mechanism of FIG. 14, in which the same reference numerals as those in FIG. 14 denote the same components. In the figure, reference numeral 520 denotes a one-dot chain line indicating the optical axes of the lens 313 and the imaging device 318. Reference numerals 521 and 522 denote a rotor and a stator that form an ultrasonic motor, respectively. Reference numeral 522 is fixed to the tube, and an ultrasonic vibration element (not shown) is provided in a portion that enters 521. A reflecting mirror 515 is attached to 521. Reference numerals 515, 521, and 522 constitute a “rotating reflecting mirror” mechanism 525 provided in the lens 313. In such a configuration, the rotor 521 can be rotated about the optical axis 520 as a central axis or stopped by applying an electrical signal to the ultrasonic vibration element. In other words, the reflecting mirror 515 can be rotated / stopped around the optical axis by the control of the ultrasonic motor. In the figure, an example in which the rotation / stop operation is controlled by an ultrasonic motor is shown, but it may be controlled by another drive source, for example, a stepping motor. The attachment angle (indicated by 523) of the reflecting mirror 515 is preferably 45 degrees with respect to the optical axis, but is not limited thereto. For example, when the angle is 45 degrees, the imaging apparatus can observe “straight side” of the image sensor application apparatus, and when the angle is larger than 45 degrees, “slightly ahead of right side” and from 45 degrees. When it is small, it is possible to observe “a little ahead of the side”. Further, it is preferable that the central axis of rotation of the rotor 521 coincides with the optical axis 520 and that the center of the photosensitive element region of the image sensor 314 constituting the imaging apparatus coincides with the optical axis 520. . In such a case, even if the reflecting mirror 515 rotates, the center of the obtained image does not fluctuate, and an image desirable for the observer can be obtained.

  In the thirteenth embodiment, it is possible to detect an image around the front end portion of the image sensor application apparatus over 360 degrees. In such a configuration, the area occupied by the image sensor can be made the same (or substantially the same) as the cross-sectional area of the circular metal tube, and as described above, the resolution characteristics and photosensitivity characteristics of the image sensor are greatly increased. Improvement can be expected, and it can be said that the effect of the present invention is great.

The reflecting mirror described above does not always rotate constantly while the image sensor application apparatus is in operation. For example, assuming the application of the image sensor application device inserted into the body,
1): The process of inserting the image sensor application device into the body
By rotating continuously, around the tip of the image sensor application device
It becomes possible to observe over 360 degrees. As a result, the inspection target
Proximity is safe and easy.
2): Process after the image sensor application device approaches the inspection object
By stopping the rotation of the reflecting mirror, the tip of the image sensor application device
Only one direction around the part can be observed in detail. Also change the observation location
If this is desired, the reflector is rotated by a small amount.
Is possible.

  In this embodiment, since the reflecting mirror is used, the captured image is reversed left and right. This reverse image can be converted into a normal image by a known image processing method.

  It is also easy to apply the configuration illustrated in the thirteenth embodiment to a “swallow type” image sensor application device called “smart pill”, “capsule endoscope”, or the like. In this application form, instead of the circular tube described above, a tablet capsule type container having a circular cross section is used. In the application mode, since the image sensor application apparatus transmits inspection information while moving in the human body, it is preferable that the reflecting mirror is constantly rotated. Further, the wiring 317 from the wiring board 316 is unnecessary, and as an alternative, the area of the image processing IC 315 and the wiring board 316 is provided with a wireless communication function to transmit information to the outside. Furthermore, in the application field, downsizing of the image sensor application apparatus is strongly required, and effective use in the apparatus is essential. In the present invention, by mounting a circular or polygonal image sensor, it is possible to satisfy the requirements and improve the characteristics of the image sensor.

  Note that the “swallow type” image sensor application device described in the preceding paragraph may be configured such that the imaging device captures only “front” of the image sensor application device without mounting a reflecting mirror. . In such a configuration, in order to obtain a wide observation field of view, the lens of the imaging device is preferably a wide-angle lens or a fish-eye lens.

  In this specification, an example in which an image sensor is mounted on an image sensor application apparatus is described. The image sensor often detects “light” such as visible light, near-infrared light, and infrared light, but is not necessarily limited thereto. For example, the present invention can be applied to an image sensor application apparatus capable of “ultrasonic imaging” by mounting an ultrasonic detection element in place of the photosensitive element of the image sensor. Even in such a case, it is possible to increase the resolution characteristics and sensitivity characteristics of ultrasonic imaging by making the sensor circular.

  In this specification, as shown in FIG. 4, the configuration of the image sensor considered as a standard configuration is described as an example. However, there are various image sensor configurations, and the present invention can be applied to all of them. As an example, a configuration without a microlens, a monochrome imaging configuration without a color filter, an amplification function for each pixel to increase sensitivity, or a photodiode itself has an amplification function. The so-called amplification-type image sensor configuration, CCD-type image sensor that reads signals from pixels via horizontal and vertical registers, and the image sensor itself has a stacked structure, so that each layer has an imaging function and signal processing. There are three-dimensional configurations in which functions, memory functions, input / output control functions, etc. are assigned. The present invention can be easily applied to such a plurality of configuration examples.

  The present invention can be widely applied to other fields in addition to application to an image sensor application apparatus equipped with an image sensor in the medical device field and the industrial device field. For example, the present invention has a great effect when applied to a field (for example, a repeater in the field of optical communication, a tip of a boring for excavating underground with a drilling machine, etc.) that needs to store an electronic circuit in a thin pipe.

300, 310, 500 Circular tube 301, 401, 451 Square image sensor 302, 314, 403, 421, 461, 471, 481
Circular image sensor 303, 324, 402, 491 Hexagonal image sensor 311, 511 Protection plate 312 Light source 313 Lens 315, 325, 350, 371, 375, 379, 383 Image processing IC
316, 360, 372, 376, 380, 384 Wiring board 317, 494 Wiring 318 Imaging device 330, 441 Sensor part 331, 352 Semiconductor substrate 332 Photosensitive element 333 Insulating layer 334 Color filter 335 Micro lens 336, 351, 356, 366 Electrode Pad 337, 357, 367 Through electrode 338, 358, 368 Wiring pattern 339, 359 Ball grid array 340 Cover glass 341 Adhesive layer 342, 370, 374, 378, 382, 423 Image sensor 390, 430 Structure 391, 424, 431 , 442 Boundary 400, 420 Wafer 410, 411, 412, 413, 415 Laser beam trajectory 425 Mask layer 426 Flow of abrasive grains 443 Resist layer 444 Etching solution or Body flow 450 Inner wall of circular tube 452, 462, 472, 482, 492 Photosensitive element region 453, 463, 473, 493 Peripheral circuit region 501 Channel 502 Tube housing imaging device 510 Transparent cylindrical window 515 Reflector 516 Direction of rotation 520 Optical axis 521 Rotor of ultrasonic motor 522 Stator of ultrasonic motor 523 Angle 525 Mechanism of “rotating reflecting mirror” provided on lens

Claims (3)

An image sensor application device having an imaging device mounted at the tip of a tube made of metal, or resin, or a combination of metal and resin, and comprising at least a lens, an image sensor, and an image processing IC,
An image sensor application device, wherein the shape of the image sensor is a circle or at least a pentagon.   The lens that is a component of the imaging device is provided with a reflecting mirror that is disposed obliquely inside the tube and has a mechanism that can rotate around the axis of the tube. The image sensor application apparatus according to claim 1. An image sensor having the circular shape or at least a pentagonal shape according to claim 1 or 2,
On the surface of the semiconductor substrate constituting the image sensor,
A rectangular photosensitive element region in which a plurality of photosensitive elements are arranged; and
Around the photosensitive element region, a peripheral circuit region including a drive circuit and a signal processing circuit of the image sensor is disposed,
On the back surface of the semiconductor substrate,
An image sensor comprising: electrical connection means for transmitting a signal from the image sensor or a signal to the image sensor.