JP2017034168A - Image pick-up device, and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus having an optical system in which an angle of principal ray incidence on an image pick-up device largely changes, and capable of improving optical characteristics.SOLUTION: In an imaging apparatus includes an optical unit in which incident angle of a light beam on an image pick-up device varies depending on zoom position, for a principal ray which may incident on another neighboring pixel when the incident angle θb of a light beam from the optical unit to an image pick-up device 3010 changes depending on the change of zoom magnification of the optical unit, a projection 3005-1 is formed on the upper plane of an optical waveguide so as to have a wide projection area on the upper plane of an optical waveguide 3006 of an image pick-up device.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image pickup element used in an image pickup apparatus, and more particularly to improvement of oblique incidence characteristics to the image pickup element.

  In recent years, with the miniaturization of video cameras and digital cameras, the optical systems used in the devices have also been miniaturized. A light ray incident on the image sensor from the optical system has a wide incident angle on the image sensor, and a light beam (chief ray) that passes through the center of the optical system other than the center of the image pickup surface is incident on the image pickup surface. It is known to lean against. Further, it is known that this light incident angle varies depending on the zoom magnification of the optical system. Further, this light incident angle becomes tighter with the miniaturization of the optical system.

  Next, a wiring layer for reading out pixel signals exists on the surface of the image sensor. It is known that the wiring layer becomes an obstacle that blocks incident light to a photodiode that performs photoelectric conversion. In order to suppress the light incidence obstruction to the photodiode due to the wiring layer, Patent Document 1 includes a high refractive index waveguide above the photodiode, and a condensing lens above the waveguide. An image sensor is described in which the positions thereof are shifted in the plane direction according to the angle.

JP 2012-54565 A

  However, in the conventional technique disclosed in Patent Document 1 described above, the incident angle of light from the optical system to the image sensor changes as the zoom magnification changes, as shown in FIGS. 9A and 9B. Problems arise.

  Reference numeral 9001 denotes a condensing lens for guiding light to the waveguide portion. Reference numeral 9002 denotes a planarizing film that planarizes the surface on which the color filter is provided. Reference numeral 9003 denotes a color filter that passes only light in a specific wavelength region. Reference numeral 9004 denotes a planarizing film that planarizes the surface on which the waveguide is provided. Reference numeral 9006 denotes a waveguide for guiding the light collected by the condenser lens to the waveguide. Light obliquely incident from the opening on the upper surface of the waveguide 9006 is reflected by the side surface of the waveguide and guided to the photodiode.

  As a material for the waveguide 9006, materials such as polyimide, DLC (Diamond Like Carbon), polysiloxane, and the like are used in addition to silicon nitride (refractive index 2.0). Reference numeral 9007 denotes an interlayer insulating film. The interlayer insulating film 9007 is formed of a light transmissive material (for example, a silicon oxide film (refractive index n = 1.43)) that transmits light. Reference numeral 9008 denotes wiring for driving the image sensor.

  Reference numeral 9009 denotes a passivation layer for protecting the photodiode from damage during the formation of the waveguide. Reference numeral 9010 denotes a photodiode for converting incident light into electrification. Reference numeral 9011 denotes a silicon substrate. Reference numeral 9012 denotes a polysilicon electrode adjacent to the photodiode 9010. Since the polysilicon electrode 9012 has a high refractive index and exhibits the same effect as the waveguide 9006, there is a problem that light is guided to other pixels. In this embodiment, this problem is also addressed. To do.

  FIG. 9A shows the condensing lens 9001 so that when a light ray whose chief ray incident angle is inclined by 5 ° enters the condensing lens, the light ray enters the center of the photodiode 9010 like the pixel (a1). The optical system of the image pick-up element which moved the position in xy plane is represented. Here, the xy plane is a plane perpendicular to the incident light beam to the center of the light receiving surface of the image sensor.

  FIG. 9A shows a case where a chief ray (incident angle of 30 °) inclined with respect to the shift amount L2 of the condenser lens 9001 is incident on the condenser lens 9001 of the pixel (a2).

  In this case, the light refracted by the condensing lens 9001 deviates from the opening of the waveguide 9006 and is reflected outside the image sensor to be lost. FIG. 9B shows a condensing lens 9001 so that when a light beam whose chief ray incident angle is inclined by 10 ° enters the condensing lens 9001, the light beam enters the center of the photodiode 9010 like the pixel (b1). The optical system of the image pick-up element which moved the position of x in the xy plane is represented. In FIG. 9B, the principal ray (incident angle −10 °) inclined in the direction opposite to the shift direction with respect to the shift amount L1 of the condenser lens 9001 is the condenser lens 9001 adjacent to the right of the pixel (b3). In this case,

  In this case, the light refracted by the condenser lens 9001 enters the opening of the waveguide 9006 of the pixel (b3) and is guided to the photodiode 9010 of the pixel b3, which causes color mixing. FIG. 9B When a light beam whose chief ray incident angle is inclined by 30 ° is incident on the condensing lens 9001 at the pixel (b2), the poly (b2) is located near the waveguide 9006 and has a refractive index similar to that of the waveguide 9006. Light leaks into the silicon electrode 9012. A polysilicon electrode 9012 having a refractive index comparable to that of the waveguide 9006 exhibits the same function as that of the waveguide 9006, and guides light leaking into the polysilicon electrode 9012 to the adjacent pixel (b3) to generate color mixing.

  In order to achieve the above object, an imaging apparatus according to the present invention is characterized by improving optical characteristics in an imaging apparatus having an optical system in which a chief ray incident angle to an imaging element changes greatly.

  According to the present invention, in an imaging apparatus capable of changing the zoom magnification, it is possible to provide a good image even if the chief ray incident angle on the image sensor changes greatly with the zoom magnification change.

The figure which shows the structure of the imaging device which concerns on Embodiment 1 of this invention. The figure which shows the structure of the optical part and imaging part which concern on Embodiment 1 of this invention. The figure which shows the structure of the image pick-up element optical layer which concerns on Embodiment 1 of this invention. The figure which shows the preparation methods of the image pick-up element which concerns on Embodiment 1 of this invention. The figure which shows a part of creation method of the image pick-up element based on Embodiment 1 of this invention. The figure which shows the structure of the image pick-up element optical layer which concerns on Embodiment 2 of this invention. The figure which shows the preparation methods of the image pick-up element which concerns on Embodiment 2 of this invention. The figure which shows a part of creation method of the image pick-up element based on Embodiment 2 of this invention. The figure which shows the structure of the conventional image pick-up element optical layer

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an imaging apparatus according to an embodiment of the present invention.

[Example 1]
Hereinafter, the configuration of the imaging apparatus according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a configuration of an imaging apparatus according to Embodiment 1 of the present invention.

  In FIG. 1, reference numeral 1001 denotes an optical unit that includes a zoom lens, a focus lens, a diaphragm mechanism, and the like disposed in a lens barrel, which will be described later, and forms a subject image on a light receiving unit of an image sensor. Each mechanism of the optical unit 1001 performs control such as autofocus by mechanically driving each unit under the control of a CPU 1004 described later. Reference numeral 1002 denotes an image sensor that converts an optical signal of an image formed by the optical unit 1001 into an electrical signal.

  The image sensor 1002 performs OB (optical black) clamping and AD conversion, generates a digital image signal, and outputs the digital image signal to the DSP 1007. Reference numeral 1004 denotes a CPU that controls the entire system. The CPU 1004 sends an instruction to each unit of the imaging apparatus using a ROM 1005 and a RAM 1006 described later. Reference numeral 1005 denotes a ROM for storing information such as firmware for driving the imaging apparatus. Reference numeral 1006 denotes a RAM for temporarily storing control information of the imaging apparatus. Reference numeral 1007 denotes a DSP.

  The DSP 1007 performs various kinds of signal processing on the image signal from the image sensor 1002, thereby generating a still image or moving image video signal (for example, a YUV signal) in a predetermined format. Furthermore, the DSP 1007 performs an exposure control operation, detection of the main subject, and detection of the distance from the imaging device based on a signal from the imaging device 1002 during live view driving. Reference numeral 1008 denotes an external interface.

  The external interface 1008 is provided with various encoders and D / A converters, and exchanges various control signals and data with external elements (in this example, the display 1012, the memory medium 1009, and the operation panel 1011). Reference numeral 1012 denotes a display that displays a captured image incorporated in the imaging apparatus. In addition to the display device incorporated in the imaging device, it is of course possible to transmit the image data to an external display device for display. Reference numeral 1009 denotes a memory medium that can appropriately store images taken on various memory cards and the like. Reference numeral 1010 denotes a memory medium controller that can replace the memory medium 1009.

  As the memory medium 1009, in addition to various memory cards, a disk medium using magnetism or light can be used. Reference numeral 1011 denotes an operation panel provided with input keys for the user to give various instructions when performing a shooting operation with the imaging apparatus. The CPU 1004 monitors an input signal from the operation panel 1011 and executes various operation controls based on the input content.

  FIG. 2 is a diagram illustrating the configuration of the optical unit and the imaging unit according to Embodiment 1 of the present invention. Here, 2001 represents a focusing surface of the optical system 1001. Point C represents the center of the angle of view, and point P represents one point other than the center. A light beam emitted from the focusing surface 2001 is guided to the imaging surface of the imaging device 1002 after passing through the optical system 1001. At this time, the point C ′ represents the image point of the point C, and the point P ′ represents the image point of the point P.

  Here, the point C ′ is perpendicularly incident on the light receiving surface of the image sensor 1002, but the point P ′. The light incident on the light receiving surface of the image sensor 1002 is inclined from the vertical direction. In general, the inclination angle increases as the distance from the center of the light receiving surface increases. FIG. 2A illustrates the chief ray incident angle from the optical unit to the imaging unit at the wide-angle zoom position. Here, the angle of incidence on the periphery of the screen is shown, and θw represents the inclination of the principal ray from the normal to the imaging surface.

  Next, FIG. 2B shows the chief ray incident angle from the optical unit to the imaging unit at the telephoto zoom position. Here again, the angle of incidence on the periphery of the screen is shown, and θt represents the inclination of the principal ray from the normal of the imaging surface. In the current compact digital camera, the angle difference between θw and θt is about several tens of degrees. However, with the miniaturization of the optical system, the angle difference between θw and θt is expected to become larger in the future. In Example 1, an optical system in which an angle difference between θw and θt exceeds 30 ° and an imaging device equipped with an imaging device corresponding to the optical system will be described.

  FIG. 3 shows a configuration of the imaging element optical layer according to Embodiment 1 of the present invention. In the imaging region, pixels are arranged on the substrate, but illustration of components other than the photodiode is omitted.

  Reference numeral 3001 denotes a condensing lens for guiding light to the waveguide portion. Reference numeral 3002 denotes a planarizing film that planarizes the surface on which the color filter is provided. Reference numeral 3003 denotes a color filter that passes only light in a specific wavelength region. Reference numeral 3004 denotes a planarizing film that planarizes the surface on which the waveguide is provided. Reference numeral 3005-1 denotes a protrusion on the upper surface of the waveguide for guiding obliquely incident light to the waveguide. Reference numeral 3005-2 denotes a slope forming portion on the upper surface of the waveguide for guiding obliquely incident light to the waveguide. Reference numeral 3006 denotes a waveguide for guiding the light collected by the condenser lens to the waveguide. Light obliquely incident from the opening on the top surface of the waveguide 3006 is reflected by the side surface of the waveguide and guided to the photodiode.

  As a material for the waveguide, materials such as polyimide, DLC (Diamond Like Carbon), polysiloxane, etc. are used in addition to silicon nitride (refractive index 2.0). Reference numeral 3007 denotes an interlayer insulating film. The interlayer insulating film 3007 is formed of a light transmissive material (for example, a silicon oxide film (refractive index n = 1.43)) that transmits light. Reference numeral 3008 denotes wiring for driving the image sensor. Reference numeral 3009 denotes a passivation layer for protecting the photodiode from damage during the formation of the waveguide.

  Reference numeral 3010 denotes a photodiode for converting incident light into electrification. Reference numeral 3011 denotes a silicon substrate. Reference numeral 3012 denotes a polysilicon electrode adjacent to the photodiode 3010. Since the polysilicon electrode 3012 has a high refractive index and exhibits the same effect as the waveguide 3006, there is a problem that light is guided to other pixels. In this embodiment, this problem is also addressed. To do.

  Assuming that the light incident angle on the imaging surface is θb, the waveguide opening diameter L, and the height of the raised portion is H, when the ML curvature is lowered to the limit, the apparent opening is L + H × cos θ at the maximum. This has the same effect as expanding the opening of the waveguide in the incident direction of the inclined light beam.

  As described above, the amount of light incident on the waveguide opening at the angle θb is increased by (L + H × cos θ) / L, and the sensitivity of the increase in the amount of light is improved. For example, when the open aperture L of the waveguide is 1000 nm, the condenser lens has no curvature, and the incident angle of light corresponds to incident light having θb of 30 °, the height of the side surface of the projection 3005-1 Is 50 nm, (L + H × cos θ) /L=1.05, and the sensitivity is improved by 5%. At this time, since the horizontal shift amount of the condensing lens itself can be suppressed to a small value, light incident on other pixels is incident upon light incident in the direction opposite to the horizontal shift direction of the condensing lens, such as θc. It becomes possible to suppress leakage.

  In the above case, it is reasonable to set the shift amount of the condensing lens so as to correspond to an intermediate angle of 30 ° to −10 °. In addition, since the light incident angle is different in the plane of the image sensor 1002, the height of the side surface of the protrusion 3005-1 is changed in the plane of the image sensor 1002.

  Specifically, at the center of the image circle where the incident angle of the chief ray to the image sensor is near vertical, the height is lowered, and at the periphery of the image circle, the incident angle of the chief ray to the image sensor is increased. Increase the height.

  Next, FIG.3 (b) changes the shape of the projection part 3005-1 of the waveguide upper surface of Fig.3 (a).

  FIG. 3B is intended to reduce light leakage to other pixels due to light incident on the polysilicon electrode 3012. In FIG. 3B, the protrusion 3005-1 on the upper surface of the waveguide is formed in a plurality of stages on the upper opening of the waveguide 3006.

  The protruding portion 3005-2 on the upper surface of the waveguide is formed by overlapping the protruding portion 3005-1 on the upper surface of the waveguide while reducing the shape so as to approximate an obliquely inclined shape.

  By adopting such a shape, light is refracted at the interface between the planarization film 3004 and the protrusion 3005-2 on the upper surface of the waveguide, and the light is refracted in a direction nearly perpendicular to the interface. For this reason, light can be collected on one side of the waveguide. For this reason, it is possible to reduce the amount of incident light with respect to the polysilicon electrode 3012 adjacent to the photodiode 3010.

  In the plane of the image sensor 1002, the shading depending on the light incident angle changes from the center to the periphery of the image circle, but the color mixture by the polysilicon electrode 3012 is in addition to the positional relationship between the polysilicon electrode 3012 and the waveguide 3006. Depends on. For this reason, by using the structure of FIG. 3A and the structure of FIG. 3B together in the plane of one imaging element 1002, the optical problem due to the opening of the waveguide 3006 and the polysilicon electrode 3012 are caused. Both optical problems can be solved.

  Next, a method for creating the imaging device according to Embodiment 1 of the present invention will be described with reference to FIG. First, as shown in FIG. 4A, a photodiode 3010 is formed by ion-implanting n-type impurities into a substrate 3011 which is a p-type silicon substrate, for example.

  Next, as shown in FIG. 4B, a passivation layer 3009 is formed after the photodiode 3010 is formed. Next, as shown in FIG. 4C, a photoresist mask 4100 is formed by using a lithography technique.

  Specifically, a photoresist film (not shown) is formed on the passivation layer 3009 by spin coating. Thereafter, the mask pattern image is transferred to the photoresist film by exposure using a photomask. Then, the photoresist mask 4100 is formed by performing development processing on the photoresist film.

  Next, as shown in FIG. 4D, the passivation layer 3009 in contact with the silicon substrate 3011 is removed. Here, part of the passivation layer 3009 is removed by etching using the photoresist mask 4100.

  Next, as shown in FIG. 4E, an interlayer insulating film 3007 is formed. For example, the interlayer insulating film 3007 is formed using a silicon oxide film. In addition to this, a wiring 3008 is sequentially formed in the interlayer insulating film 3007 by a so-called damascene process. The wiring 3008 is sequentially formed of a metal material such as aluminum or copper, for example. In this manner, the interlayer insulating film 3007 is formed so as to include the wiring 3008 therein.

  Next, as shown in FIG. 4F, a photoresist mask 4101 is formed using a lithography technique.

  In this embodiment, this photoresist mask 4101 is formed so that the surface of the region where the waveguide 3006 is formed is exposed and the other region is covered in the interlayer insulating film 3007.

  Next, as shown in FIG. 4G, an opening of the interlayer insulating film 3007 is formed. Here, part of the interlayer insulating film 3007 is removed by etching using the photoresist mask 4101, so that this opening is formed in the interlayer insulating film 3007.

  Specifically, as shown in FIG. 4G, an opening of the interlayer insulating film 3007 is formed in a portion of the interlayer insulating film 3007 corresponding to the light receiving surface of the photodiode 3010.

  In the present embodiment, the side surface of the opening of the interlayer insulating film 3007 is along the z direction perpendicular to the light receiving surface of the photodiode 3010, and the xy plane along the light receiving surface at the opening of the interlayer insulating film 3007. The opening of this interlayer insulating film 3007 is formed so that the surface in the direction of is smaller than the area of the light receiving surface of the photodiode 3010. Further, the opening is formed so that the center of the opening corresponds to the center of the light receiving surface of the photodiode 3010 in the direction of the xy plane along the light receiving surface of the photodiode 3010.

  Here, the xy plane is a plane perpendicular to the incident light beam to the center of the image sensor. Also, the direction parallel to the incident light beam to the center of the light receiving surface of the image sensor is the z direction. Here, the opening of the interlayer insulating film 3007 is formed by performing anisotropic etching.

  For example, an anisotropic etching process using RIE (Reactive Ion Etching) or ECR (Electron Cyclotron Resonance) plasma is performed using CF 4 gas. Thus, the interlayer insulating film 3007 is etched in the vertical direction until the surface of the passivation layer 3009 is exposed, and an opening of the interlayer insulating film 3007 is formed. Then, the photoresist mask 4101 is removed by performing a process such as an ashing process.

  Next, as shown in FIG. 4H, a waveguide 3006 is formed. Here, a waveguide 3006 is formed inside an opening formed by removing a part of the interlayer insulating film 3007. For example, after a silicon nitride (SiN) film is formed by plasma CVD so as to fill the inside of an opening formed by removing a part of the interlayer insulating film 3007, a CMP (Chemical Mechanical Polishing) process is performed. To flatten the surface. Thus, the waveguide 3006 is formed in the opening of the interlayer insulating film 3007.

  Next, as shown in FIG. 4H, a protrusion 3005-1 on the upper surface of the waveguide is formed. Here, the planarization film 3004-2 is formed so as to cover the waveguide 3006 and the interlayer insulating film 3007. For example, as in the case of the interlayer insulating film 3007, the planarizing film 3004-2 is formed using a silicon oxide film. Next, as shown in FIG. 4I, a photoresist mask 4102 is formed on the planarizing film 3004-2. Then, in the same manner as in the case of the photoresist mask 4100 described above, a photoresist mask 4102 is formed over the planarization film 3004-2 using a lithography technique.

  In the present embodiment, in the planarizing film 3004-2, the photoresist mask 4102 is formed so that the surface of the region where the protrusion 3005-1 is formed on the upper surface of the waveguide is exposed and the other region is covered. To do.

  Next, as shown in FIG. 4J, an opening of the planarizing film 3004-2 is formed. Here, an opening of the planarization film 3004-2 is formed by removing part of the planarization film 3004-2 by etching using the photoresist mask 4102.

  Specifically, as shown in FIG. 4J, the opening of the planarization film 3004 is formed so that the planarization film 3004-2 includes a portion corresponding to the protrusion 3005-1 on the upper surface of the waveguide. Form.

  In the present embodiment, the side surface of the opening of the planarizing film 3004-2 is along the z direction perpendicular to the light receiving surface of the photodiode 3010, and the photodiode 3010 is formed through the opening of the planarizing film 3004-2. The opening portion of the planarizing film 3004-2 is formed so that the surface in the direction of the xy plane along the light receiving surface is smaller than the area of the incident surface of the waveguide 3006. Further, of the side surface of the waveguide 3006, the planarization film 3004 is arranged so that the end surface of the planarization film 3004 corresponds to the end of the side surface on the side where the oblique incident light travels. -2 openings are formed.

  For example, as in the case of the opening of the interlayer insulating film 3007 described above, the opening of the planarizing film 3004-2 is formed by performing an anisotropic etching process. Then, the photoresist mask 4102 is removed by a process such as an ashing process.

  Next, as shown in FIG. 4K, a protrusion 3005-1 on the upper surface of the waveguide is formed. Here, a protrusion 3005-1 on the upper surface of the waveguide is formed inside the opening formed by removing a part of the planarizing film 3004-2. For example, the protrusion 3005-1 on the upper surface of the waveguide is formed in the same manner as in the case of the waveguide 3006.

  Next, as shown in FIG. 4L, a planarizing film 3004-1 is formed. Here, the planarizing film 3004-1 is formed so as to cover the planarizing film 3004-2 and the protrusion 3005-1 on the upper surface of the waveguide. For example, as in the case of the planarization film 3004-2, the planarization film 3004-1 is formed of a silicon oxide film.

  A combination of the planarizing film 3004-1 and the planarizing film 3004-2 corresponds to the planarizing film 3004 in FIG. Thereafter, as shown in FIG. 3A, a color filter 3003, a planarizing film 3002, and a condenser lens 3001 are formed.

  Here, a color filter 3003 is formed above the planarization film 3004. For example, a color filter 3003 is formed by applying a coating liquid containing a color pigment of each color and a photoresist resin by a spin coating method to form a coating film, and then patterning the coating film by a lithography technique. A filter layer for each color is formed. Then, a planarization film 3002 is formed so as to planarize the surface on which the color filter 3003 is formed. Thereafter, as shown in FIG. 3A, a condensing lens 3001 is formed on the planarizing film 3002 to complete the image sensor 1001.

  Next, the creation method of FIG. 3B will be described with reference to FIG. 4 and FIG. FIG. 5 is a part of a method for producing an image sensor according to Embodiment 1 of the present invention. 3 (b), in addition to the steps from FIG. 4 (a) to FIG. 4 (g) up to the step of forming the waveguide 3006, in addition to the steps from FIG. 5 (m) to FIG. This can be realized by repeating the step r) and laminating the oblique portion of the waveguide and the planarization layer.

  Specifically, an opening of the interlayer insulating film 3007 is formed in a portion corresponding to the light receiving surface of the photodiode 3010 in the interlayer insulating film 3007 in FIG. Thereafter, as shown in FIG. 5M, a planarizing film 3004-5 and a photoresist mask 4103 are formed on the upper surface of the waveguide 3006.

  Next, as shown in FIG. 5 (n), an opening of the planarizing film 3004-5 is formed. Here, an opening of the planarization film 3004-5 is formed by removing part of the planarization film 3004-5 by etching using the photoresist mask 4103.

  Specifically, as shown in FIG. 5 (n), the planarization film 3004-5 includes a portion corresponding to a part 3005-4 of the slope forming portion on the upper surface of the waveguide. -5 openings are formed.

In this embodiment, the side surface of the opening portion of the planarizing film 3004-5 is along the z direction perpendicular to the light receiving surface of the photodiode 3010, and the photodiode 3010 is formed at the opening portion of the planarizing film 3004-5. The plane in the direction of the xy plane along the light receiving surface is smaller than the area of the incident surface of the waveguide 3006 and the side surface of the waveguide 3006 on the side where the inclined incident light beam first comes into contact is higher. An opening of the chemical film 3004-5 is formed.
Then, the photoresist mask 4103 is removed.

  Next, as shown in FIG. 5 (o), a part 3005-4 of the slope forming portion on the upper surface of the waveguide is formed. Here, a part 3005-4 of the slope forming part on the upper surface of the waveguide is formed inside the opening formed by removing part of the planarizing film 3004-2. Next, as shown in FIG. 5P, a planarizing film 3004-4 and a photoresist mask 4104 are formed. Next, as shown in FIG. 5 (q), an opening of the planarizing film 3004-4 is formed. Here, an opening of the planarization film 3004-4 is formed by removing part of the planarization film 3004-4 by etching using the photoresist mask 4104.

  Specifically, as shown in FIG. 5 (q), the planarizing film 3004-4 includes a portion corresponding to a part 3005-3 of the slope forming portion on the upper surface of the waveguide. -4 openings are formed.

  In this embodiment, the side surface of the opening portion of the planarizing film 3004-4 is along the z direction perpendicular to the light receiving surface of the photodiode 3010, and the photodiode 3010 is formed at the opening portion of the planarizing film 3004-4. The surface in the direction of the xy plane along the light receiving surface is smaller than the area of the incident surface of the part 3005-4 of the slope forming portion on the upper surface of the waveguide, and the incident light beam inclined by the waveguide 3006 comes into contact first. The opening portion of the planarizing film 3004-4 is formed so that the side surface on the side becomes higher. Then, the photoresist mask 4103 is removed by a process such as an ashing process.

  Next, as shown in FIG. 5 (r), a part 3005-3 of the slope forming portion on the upper surface of the waveguide is formed.

  By repeating the above-described processing shown in FIGS. 5 (p) to 5 (r) with a scale stack sufficiently smaller than the wavelength of light, an inclined surface is optically formed on the upper surface of the waveguide as shown in FIG. 3 (b). Is possible.

  Next, as shown in FIG. 5S, a planarizing film 3004-3 is formed. Here, the planarization film 3004-3 is formed so as to cover the planarization film 3004-4 and a part 3005-3 of the slope forming portion on the upper surface of the waveguide. A combination of the planarizing film 3004-3, the planarizing film 3004-4, and the planarizing film 3004-5 corresponds to the planarizing film 3004 in FIG. Thereafter, as shown in FIG. 3B, a color filter 3003, a planarizing film 3002, and a condenser lens 3001 are formed.

Here, a color filter 3003 is formed above the planarization film 3004. The formation method is the same as in FIG.
Then, a planarization film 3002 is formed so as to planarize the surface on which the color filter 3003 is formed.

  Thereafter, as shown in FIG. 3B, a condensing lens 3001 is formed to complete the image sensor 1001.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

  By adopting the configuration as described above, in an imaging apparatus having an optical system in which the chief ray incident angle to the imaging element changes greatly, the amount of light guided to the waveguide is increased while suppressing the mixing of light from other pixels. This can provide an improvement in optical properties.

[Example 2]
The configuration of the imaging apparatus according to the second embodiment of the present invention will be described below with reference to FIGS. First, with reference to FIG. 6, the configuration of the imaging apparatus according to the second embodiment of the present invention will be described.

  FIG. 6 shows the configuration of the imaging element optical layer according to Embodiment 2 of the present invention. In the imaging region, pixels are arranged on the substrate, but illustration of components other than the photodiode is omitted. 3001 to 3004 and 3006 to 3012 are the same as those in the first embodiment. It is a waveguide for guiding the light condensed by the condenser lens to the waveguide. Light obliquely incident from the opening on the top surface of the waveguide 3006 is reflected by the side surface of the waveguide and guided to the photodiode.

  Reference numeral 3013-1 denotes a protrusion on the lower surface of the waveguide for guiding obliquely incident light to the waveguide. Reference numeral 3013-2 denotes a slope forming portion on the lower surface of the waveguide for guiding obliquely incident light to the waveguide. For the materials of 3013-1 and 3013-2, materials such as polyimide, DLC (Diamond Like Carbon), and polysiloxane are used in addition to silicon nitride (refractive index 2.0).

  As compared with the case where the incident angle of light on the imaging surface is θf and the waveguide 3006 is in direct contact with the passivation layer 3009, there is an effect equivalent to narrowing the lateral width of the waveguide 3006. Further, in FIG. 6, the number of reflections of incident light on the side surface of the waveguide 3006 can be reduced by keeping the width of the waveguide 3006 wide. This makes it possible to reduce light leakage into the polysilicon electrode 3012 while suppressing light loss due to reflection of incident light on the side surface of the waveguide 3006.

  As described above, the amount of light incident on the waveguide opening at the angle θb with respect to the waveguide 3006 having a high refractive index and the protrusion 3013-1 on the lower surface of the waveguide is guided to the photodiode 3010 immediately below, and the amount of increase in the amount of light is increased. Sensitivity is improved. Further, since the positional relationship between the polysilicon electrode 3012 and the photodiode 3010 is equal in the plane of the image sensor 1002, the height of the lower surface protrusion 3013-2 has the same positional relationship in the plane of the image sensor 1002.

  In FIG. 6B, the protrusion 3013-1 on the lower surface of the waveguide is formed in a plurality of layers with respect to the lower opening of the waveguide 3006. The protruding portion 3013-1 on the lower surface of the waveguide is formed by overlapping the protruding portion 3013-1 on the lower surface of the waveguide while being reduced in size until it can be approximated to an obliquely inclined shape.

  By adopting such a shape, light is reflected at the interface between the interlayer insulating film 3007 and the protrusion 3013-1 on the lower surface of the waveguide, and the light is guided in a direction far from the polysilicon electrode 3012. For this reason, light can be collected on one side of the waveguide 3006. For this reason, it is possible to reduce the amount of incident light with respect to the polysilicon electrode 3012 adjacent to the photodiode 3010.

  With reference to FIG. 7, a method of creating an imaging apparatus according to Embodiment 2 of the present invention will be described. First, FIGS. 7A to 7D are the same as FIGS. 4A to 4D. Next, as shown in FIG. 7E, an interlayer insulating film 3007-2 is formed. For example, this interlayer insulating film 3007-2 is formed using a silicon oxide film. Next, as shown in FIG. 7F, a photoresist mask 6002 is formed.

Thereafter, an interlayer insulating film 3007-2 is formed on the upper surface of the silicon substrate 3011.
Although not shown here, a lower insulating film (not shown) is formed on the surface of the substrate 3011. Thereafter, an upper insulating film (not shown) is formed on the lower insulating film (not shown). Then, for example, polysilicon electrodes 3012 are sequentially formed from polysilicon. In addition, wiring 3008 (not shown) is sequentially formed in the upper insulating film by a so-called damascene process. The wiring 3008 is sequentially formed of a metal material such as aluminum or copper, for example. In this manner, the interlayer insulating film 3007 is formed so as to include the polysilicon electrode 3012 and the wiring 3008 therein. Then, a photoresist mask 6002 is formed using the lithography technique as in the first embodiment.

  In this embodiment, the photoresist mask 6002 is formed so that a part of the surface of the region where the passivation layer 3009 is formed is exposed and the other region is covered in the interlayer insulating film 3007-2.

  Next, an opening is formed as shown in FIG. Here, part of the interlayer insulating film 3007-2 is removed by etching using the photoresist mask 6002, so that the opening is formed in the interlayer insulating film 3007-2.

  Specifically, as shown in FIG. 4G, an opening of the interlayer insulating film 3007-2 is formed in a portion corresponding to the light receiving surface of the photodiode 3010 in the interlayer insulating film 3007-2.

  In this embodiment, the side surface of the opening of the interlayer insulating film 3007-2 is along the z direction perpendicular to the light receiving surface of the photodiode 3010, and the light receiving surface is formed at the opening of the interlayer insulating film 3007-2. The opening of this interlayer insulating film 3007-2 is formed so that the surface in the direction of the xy plane along the surface is smaller than the area of the light receiving surface of the photodiode 3010 and is spaced from the polysilicon electrode 3012. Here, the opening of the interlayer insulating film 3007-2 is formed by performing an anisotropic etching process.

  Again, anisotropic etching is performed. Thus, the interlayer insulating film 3007-2 is etched in the vertical direction until the surface of the passivation layer 3009 is exposed, and an opening of the interlayer insulating film 3007-2 is formed. Then, the photoresist mask 6002 is removed by performing a process such as an ashing process.

  Next, as shown in FIG. 7H, a protrusion 3013-1 at the bottom of the waveguide is formed. Here, a protrusion 3013-1 at the lower part of the waveguide is formed inside an opening formed by removing a part of the interlayer insulating film 3007-2.

  For example, after a silicon nitride (SiN) film is formed by plasma CVD so as to fill the opening of the planarization film 3004-2, the surface thereof is planarized by CMP treatment. By doing so, a protrusion 3013-1 at the bottom of the waveguide is formed in the opening of the interlayer insulating film 3007-2.

  Next, as shown in FIG. 7I, a waveguide 3006 is formed. Here, the interlayer insulating film 3007-1 is formed so as to cover the protruding portion 3013-1 and the interlayer insulating film 3007-2 under the waveguide. For example, as in the case of the interlayer insulating film 3007-2, this interlayer insulating film 3007-1 is formed using a silicon oxide film.

  Next, as shown in FIG. 7J, a photoresist mask 6003 is formed on the waveguide 3006. Then, in the same manner as in the case of the above-described photoresist mask 6002, a photoresist mask 6003 is formed over the interlayer insulating film 3007-1 using a lithography technique.

  In this embodiment, this photoresist mask 6003 is formed so that the surface of the region where the waveguide 3006 is formed is exposed and the other region is covered in the interlayer insulating film 3007-1. Next, as shown in FIG. 7K, an opening of the interlayer insulating film 3007-1 is formed. Here, an opening of the interlayer insulating film 3007-1 is formed by removing part of the interlayer insulating film 3007-1 by etching using the photoresist mask 6003. Specifically, as shown in FIG. 7K, the opening of the interlayer insulating film 3007-1 is formed so as to include a portion corresponding to the waveguide 3006 in the interlayer insulating film 3007-1.

  In this embodiment, the side surface of the opening of the interlayer insulating film 3007-1 is along the z direction perpendicular to the light receiving surface of the photodiode 3010, and the photodiode 3010 is formed in the opening of the interlayer insulating film 3007-1. The opening of the interlayer insulating film 3007-1 is formed so that the surface in the direction of the xy plane along the light receiving surface is larger than the area of the incident surface of the protrusion 3007-2 at the bottom of the waveguide.

  In addition, in the direction of the xy plane along the light receiving surface of the photodiode 3010, the planarization film 3004-2 is arranged such that the center of the opening of the planarization film 3004 corresponds to the center of the light receiving surface of the photodiode 3010. An opening is formed. For example, as in the case of the opening of the interlayer insulating film 3007-2 described above, the opening of the interlayer insulating film 3007-1 is formed by performing an anisotropic etching process. Then, the photoresist mask 6003 is removed by a process such as an ashing process.

Next, as shown in FIG. 7L, a waveguide 3006 is formed. Here, a waveguide 3006 is formed inside an opening formed by removing a part of the planarizing film 3004-2. For example, the waveguide 3006 is formed in the same manner as in the case of the interlayer insulating film 3007-1. Then, the planarization film 300 is formed so as to planarize the surface on which the waveguide 3006 is formed.
2 is formed.

  Thereafter, as shown in FIG. 6A, a color filter 3003, a planarizing film 3002, and a condenser lens 3001 are formed. The formation method of the color filter 3003 is the same as that in the first embodiment. Thereafter, as shown in FIG. 6A, a planarization film 3004, a color filter 3003, a planarization film 3002, and a condenser lens 3001 are stacked from the bottom to complete the imaging device 1001.

  Next, a method for creating FIG. 6B will be described. FIG. 8 shows a part of a method of creating an image sensor according to the second embodiment of the invention. The method up to FIG. 7D is the same as the method described above.

  Next, as shown in FIG. 8M, an interlayer insulating film 3007-4 is formed. Next, as shown in FIG. 8N, a photoresist mask 6004 is formed on the interlayer insulating film 3007-4. Next, as shown in FIG. 8O, an opening of the interlayer insulating film 3007-4 is formed.

Here, an opening of the interlayer insulating film 3007-4 is formed by removing a part of the flat interlayer insulating film 3007-4 by etching using the photoresist mask 6004.
Specifically, as shown in FIG. 5 (n), the planarizing film 3004 includes an interlayer insulating film 3007-4 so as to include a part corresponding to a part 3013-5 of the slope forming part on the lower surface of the waveguide. -5 openings are formed. The opening portion of the planarizing film 3004-5 is opened at a position immediately above the photodiode 3011 and away from the polysilicon electrode 3012.
Then, the photoresist mask 6004 is removed.

  Next, as shown in FIG. 8P, a part 3013-5 of the slope forming part on the lower surface of the waveguide is formed inside the opening formed by removing a part of the interlayer insulating film 3007-4. Further, the interlayer insulating film 3007-3 is formed so as to cover the interlayer insulating film 3007-4 and a part 3013-5 of the slope forming portion on the lower surface of the waveguide.

  Next, as shown in FIG. 8Q, a photoresist mask 6005 is formed. Next, as shown in FIG. 8R, an opening of the interlayer insulating film 3007-3 is formed. Here, an opening of the interlayer insulating film 3007-3 is formed by removing a part of the flat interlayer insulating film 3007-3 by etching using the photoresist mask 6004.

  Specifically, as shown in FIG. 8R, the interlayer insulating film 3007-3 includes an interlayer insulating film 3007-3 so as to include a portion corresponding to a part 3013-4 of the slope forming portion on the lower surface of the waveguide. -3 openings are formed. Further, the opening of the interlayer insulating film 3007-3 is opened directly above the photodiode 3010 and wider than a part 3013-5 of the inclined surface forming portion on the lower surface of the waveguide.

  Next, as shown in FIG. 8S, a part 3013-4 of the slope forming portion on the lower surface of the waveguide is formed.

  8B to 8S is repeated at a scale sufficiently smaller than the wavelength of light to optically form a slope on the lower surface of the waveguide as shown in FIG. 6B. It becomes possible. Thereafter, as shown in FIG. 6B, an interlayer insulating film 3007, a waveguide 3006, a planarizing film 3004, a color filter 3003, a planarizing film 3002, and a condenser lens 3001 are laminated from below, The image sensor 1001 is completed.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

  By adopting the configuration as described above, in an image pickup apparatus having an optical system in which the chief ray incident angle to the image pickup device changes greatly, the amount of leakage light to the polysilicon electrode around the photodiode is reduced and the optical characteristics are improved. Can be provided.

1001 Optical part, 1002 Image sensor, 1003 System control part,
1004 CPU, 1005 ROM, 1006 RAM, 1007 DSP,
1008 External interface, 1009 Memory medium,
1010 Memory medium controller, 1011 operation panel, 1012 display,
2001 focusing surface, 3001 condenser lens, 3002 flattening film,
3003 color filter, 3004 planarization film, 3004-1 planarization film,
3004-2 planarization film, 3004-3 planarization film, 3004-4 planarization film,
3004-5 planarization film, protrusion of 3005-1 waveguide upper surface,
3005-2 The slope forming part on the upper surface of the waveguide,
3005-3 A part of the slope forming part on the upper surface of the waveguide,
3005-4 part of the slope forming part on the upper surface of the waveguide, 3006 waveguide,
3007 Interlayer insulating film, 3008 wiring, 3009 passivation layer,
3010 photodiode, 3011 silicon substrate, 3012 polysilicon electrode,
3013-1 Projecting portion on the lower surface of the waveguide, 3013-2 Slope forming portion on the lower surface of the waveguide,
4100 photoresist mask, 4101 photoresist mask,
4102 photoresist mask, 4103 photoresist mask,
4104 photoresist mask, 6001 photoresist mask,
6002 photoresist mask, 6003 photoresist mask,
6004 photoresist mask, 6005 photoresist mask,
9001 condenser lens, 9002 planarization film, 9003 color filter,
9004 planarization film, 9006 waveguide, 9007 interlayer insulation film, 9008 wiring,
9009 passivation layer, 9010 photodiode,
9011 Silicon substrate, 9012 Polysilicon electrode

Claims (8)

An imaging device having a step on the waveguide upper surface and an optical unit in which the incident angle of light to the imaging device differs depending on the zoom position so that the projected area of the waveguide upper surface is widened against the assumed principal ray An imaging apparatus characterized by that. An imaging device in which the upper surface of the waveguide is inclined with respect to the Si surface, and the incident angle of light on the imaging device is different depending on the zoom position so that the projected area of the upper surface of the waveguide is larger than the assumed principal ray. An imaging apparatus comprising an optical unit. Equipped with an image sensor that has a step on the bottom surface of the waveguide so that the gap between the waveguide and the PolySi electrode on the Si surface closest to the waveguide opens, and an optical unit in which the incident angle of light to the image sensor varies depending on the zoom position An imaging device characterized by the above. An imaging device in which the waveguide lower surface is inclined with respect to the Si surface so that a gap between the waveguide and the PolySi electrode on the Si surface closest to the waveguide is opened, and the incident angle of light on the imaging device depends on the zoom position. An imaging device equipped with different optical units. The imaging device according to claim 1, wherein an imaging device having a step provided on an upper surface of the waveguide is mounted so that a waveguide wall surface in a traveling direction of the inclined principal ray is higher than an assumed principal ray. apparatus. The imaging device according to claim 2, wherein an imaging device having an inclination on an upper surface of the waveguide is mounted so that a waveguide wall surface in a traveling direction of the inclined principal ray is higher than an assumed principal ray. apparatus. The image pickup apparatus according to claim 1, wherein an image pickup device is mounted in which a step amount on the upper surface of the waveguide is made different for each pixel and an incident angle of a principal ray incident on each pixel is made proportional to the step amount. The image pickup apparatus according to claim 2, wherein an image pickup device in which the amount of inclination of the upper surface of the waveguide is changed for each pixel and the incident angle of the chief ray incident on each pixel is proportional to the step amount is mounted.