JP2013168546A - Image sensor, method of manufacturing the same, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress loss of light more effectively.SOLUTION: In an image sensor, a light shielding film is formed on a side on which light is radiated with respect to the semiconductor substrate provided with a light receiving unit to generate charges according to received light; and a wiring layer is formed on a side on which light is radiated with respect to the light shielding film. In addition, in order to provide an optical waveguide to transmit light to the light receiving unit, an opening portion is formed in the light shielding film and the wiring layer such that an opening formed in the light shielding film is larger in a radial direction by a predetermined interval than an opening right above the light shielding film. This technique is applicable to a CMOS image sensor, for example.

Description

  The present disclosure relates to an imaging device, a manufacturing method, and an electronic device, and more particularly, to an imaging device, a manufacturing method, and an electronic device that can more effectively suppress light loss.

  Conventionally, solid-state imaging devices such as CMOS (Complementary Metal Oxide Semiconductor) image sensors and CCDs (Charge Coupled Devices) have been widely used in digital still cameras, digital video cameras, and the like. In recent years, CMOS image sensors have been widely used for solid-state image sensors mounted on mobile devices such as mobile phone devices having an imaging function from the viewpoint of low power supply voltage and low power consumption. Yes.

  For example, incident light incident on a CMOS image sensor is photoelectrically converted in a PD (Photodiode) which is a photoelectric conversion unit included in the pixel. Then, the charge generated in the PD is transferred to a floating diffusion region (FD) that is a floating diffusion region via a transfer transistor, and the amplification transistor outputs a pixel signal at a level corresponding to the charge accumulated in the FD. Is output.

  By the way, in a CMOS image sensor, when rolling shutter photography is performed in which charge is transferred from PD to FD for each row of pixels, the exposure period for accumulating photocharges cannot be made consistent for all pixels. Distortion may occur. In order to avoid the occurrence of such distortion, it is necessary to perform global shutter photography in which the charges accumulated in the PD are transferred simultaneously in all pixels.

  In view of this, for example, a CMOS image sensor has been proposed in which a charge holding region is provided for each pixel so as to achieve simultaneous storage in each pixel and perform global shutter photography. Thus, in a CMOS image sensor in which a charge holding region is provided for each pixel, a light shielding film is provided so as to cover the semiconductor substrate in order to prevent light from entering the charge holding region.

  Also, in a CMOS image sensor, an opening is formed in a light shielding film and a wiring layer laminated on the light shielding film, and an optical waveguide is provided in the opening, thereby efficiently transmitting light to the PD. Can do. However, in the configuration in which the optical waveguide is formed so as to be adjacent to the light shielding film, there is a concern that light propagated through the optical waveguide is lost due to reflection or absorption by the metal light shielding film.

  On the other hand, the applicant of this application has proposed a solid-state imaging device in Patent Document 1 in which the light collection efficiency is improved by forming a hollow layer between the light shielding film and the optical waveguide.

JP 2009-181980 A

  By the way, in recent years, CMOS image sensors have been miniaturized, and it is assumed that the sensitivity of the PD decreases as the aspect ratio (ratio of the thickness of the wiring layer to the cell size) increases. Therefore, it has been demanded that the loss of light be effectively suppressed to avoid a decrease in sensitivity of the PD.

  This indication is made in view of such a situation, and makes it possible to control loss of light more effectively.

  An imaging device according to one aspect of the present disclosure includes a semiconductor substrate on which a light receiving portion that generates an electric charge according to received light is formed, and a light shielding film that is formed on a side where light is irradiated to the semiconductor substrate. A wiring layer formed on the light-irradiating side of the light-shielding film, and an opening formed in the light-shielding film and the wiring layer to provide an optical waveguide for propagating light to the light-receiving unit. The opening is formed such that the opening formed in the light shielding film is wider in the radial direction by a predetermined interval than the opening immediately above the light shielding film.

  In one embodiment of the present disclosure, a manufacturing method includes forming a light-shielding film on a light-irradiating side of a semiconductor substrate on which a light-receiving portion that generates an electric charge according to received light is formed, Forming an opening in the light shielding film and the wiring layer in order to form a wiring layer on the side irradiated with light and to provide an optical waveguide for propagating light in the light receiving portion, The openings formed in the light shielding film are formed so as to be wider in the radial direction by a predetermined interval than the openings immediately above the light shielding film.

  An electronic apparatus according to one aspect of the present disclosure includes a semiconductor substrate on which a light receiving portion that generates an electric charge according to received light is formed, and a light shielding film that is formed on a side where light is irradiated to the semiconductor substrate. A wiring layer formed on the light-irradiating side of the light-shielding film, and an opening formed in the light-shielding film and the wiring layer to provide an optical waveguide for propagating light to the light-receiving unit. The opening includes an imaging element formed such that an opening formed in the light shielding film is wider in a radial direction by a predetermined interval than an opening immediately above the light shielding film.

  In one aspect of the present disclosure, the opening formed in the light shielding film is formed to be wider in the radial direction by a predetermined interval than the opening immediately above the light shielding film.

  According to one aspect of the present disclosure, light loss can be more effectively suppressed.

It is a block diagram showing an example of composition of an embodiment of an image sensor to which this art is applied. It is a figure showing an example of section composition of an image sensor. It is a flowchart explaining the manufacturing method of an image pick-up element. It is sectional drawing of the vicinity of the opening part in a metal light shielding film. It is a figure which shows distribution of the light energy in an optical waveguide. It is a figure which shows the relationship between the space | interval in the opening part of a metal light shielding film, and the light intensity. It is a figure which shows the modification of an optical waveguide. It is a block diagram which shows the structural example of the imaging device mounted in an electronic device.

  Hereinafter, specific embodiments to which the present technology is applied will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram illustrating a configuration example of an embodiment of an image sensor to which the present technology is applied.

  As shown in FIG. 1, the imaging device 11 is a CMOS image sensor, and includes a pixel array unit 12, a vertical drive unit 13, a column processing unit 14, a horizontal drive unit 15, an output unit 16, and a drive control unit 17. Is done.

  The pixel array unit 12 includes a plurality of pixels 21 arranged in an array, and is connected to the vertical driving unit 13 via a plurality of horizontal signal lines 22 corresponding to the number of rows of the pixels 21. The column processing unit 14 is connected through a plurality of vertical signal lines 23 corresponding to the number of columns. That is, the plurality of pixels 21 included in the pixel array unit 12 are respectively arranged at points where the horizontal signal lines 22 and the vertical signal lines 23 intersect.

  The vertical drive unit 13 supplies a drive signal (transfer signal, selection signal, reset signal, etc.) for driving each pixel 21 to the horizontal signal line 22 for each row of the plurality of pixels 21 included in the pixel array unit 12. To supply sequentially.

  The column processing unit 14 extracts a signal level of the pixel signal by performing a CDS (Correlated Double Sampling) process on the pixel signal output from each pixel 21 via the vertical signal line 23. Pixel data corresponding to the amount of light received by the pixel 21 is acquired.

  The horizontal driving unit 15 outputs a driving signal for sequentially outputting pixel data acquired from each pixel 21 from the column processing unit 14 for each column of the plurality of pixels 21 included in the pixel array unit 12. 14 are sequentially supplied.

  The pixel data is supplied from the column processing unit 14 to the output unit 16 at a timing according to the drive signal of the horizontal driving unit 15, and the output unit 16 amplifies the pixel data, for example, to the signal processing circuit in the subsequent stage. Output.

  The drive control unit 17 controls the drive of each block inside the image sensor 11. For example, the drive control unit 17 generates a clock signal according to the drive cycle of each block and supplies the clock signal to each block.

  Further, the pixel 21 includes a PD 31, a first transfer transistor 32, a memory unit 33, a second transfer transistor 34, an FD 35, an amplification transistor 36, a selection transistor 37, and a reset transistor 38, as shown in the upper right of FIG. It is configured.

  The PD 31 is a light receiving unit that receives light incident on the image sensor 11, and generates and accumulates charges corresponding to the amount of received light.

  The first transfer transistor 32 is driven in accordance with a first transfer signal supplied from the vertical drive unit 13 via the horizontal signal line 22, and when the first transfer transistor 32 is turned on, the charge accumulated in the PD 31. Is transferred to the memory unit 33.

  The memory unit 33 holds electric charges transferred from the PD 31 via the first transfer transistor 32.

  The second transfer transistor 34 is driven according to the second transfer signal supplied from the vertical drive unit 13 via the horizontal signal line 22, and is stored in the memory unit 33 when the second transfer transistor 34 is turned on. The charged electric charge is transferred to the FD 35.

  The FD 35 is a floating diffusion region having a predetermined capacitance formed at a connection point between the second transfer transistor 34 and the gate electrode of the amplification transistor 36, and is transferred from the memory unit 33 via the second transfer transistor 34. Accumulates charge.

  The amplification transistor 36 is connected to the power supply potential Vdd, amplifies the charge accumulated in the FD 35, and outputs a pixel signal having a level corresponding to the charge to the vertical signal line 23 via the selection transistor 37.

  The selection transistor 37 is driven according to a selection signal supplied from the vertical driving unit 13 via the horizontal signal line 22, and when the selection transistor 37 is turned on, a pixel signal output from the amplification transistor 36 is output to the vertical signal line 23. It becomes possible.

  The reset transistor 38 is driven in accordance with a reset signal supplied from the vertical drive unit 13 via the horizontal signal line 22. When the reset transistor 38 is turned on, the charge accumulated in the FD 35 is discharged to the reset potential Vrst, and the FD 35 Is reset. At this time, when the first transfer transistor 32 and the second transfer transistor 34 are simultaneously turned on, the charges accumulated in the PD 31 and the memory unit 33 are also reset.

  Thus, the image sensor 11 is configured, and charges are transferred from the PD 31 to the memory unit 33 simultaneously in all the pixels 21 included in the pixel array unit 12. Thereafter, for each row of the pixels 21, the charge held in the memory unit 33 is transferred to the FD 35, and a pixel signal having a level corresponding to the charge is read through the vertical signal line 23.

  Next, a cross-sectional configuration example of the image sensor 11 will be described with reference to FIG.

  FIG. 2 shows a cross section in the vicinity of one pixel 21 included in the image sensor 11, and the image sensor 11 is irradiated with light from the upper side of FIG. 2. The imaging device 11 has a base insulating film 42, a metal light shielding film 43, an antireflection film 44, a wiring layer 45, a passivation film 46, a light, and a semiconductor substrate 41 on which the PD 31 and the memory unit 33 constituting the pixel 21 are formed. The transparent embedded film 47, the planarizing film 48, the color filter layer 49, and the on-chip lens layer 50 are laminated.

  In the semiconductor substrate 41, for example, a second conductivity type well (P well) is formed on a first conductivity type (for example, N type) substrate, and the PD 31 is provided for each pixel 21 in the P well. An impurity region (N-type region) of the first conductivity type that constitutes is formed. Further, in the semiconductor substrate 41, a first conductivity type impurity region (N-type region) constituting the memory unit 33 is formed at a position spaced apart from the PD 31 for each pixel 21 with respect to the P well. The

  The base insulating film 42 is a film having an insulating property such as a silicon oxide film (SiO 2), and is directly formed on the surface of the semiconductor substrate 41.

  The metal light shielding film 43 is a film formed of, for example, a metal having a light shielding property such as silicide, tungsten (W), copper (Cu), aluminum (Al), cobalt (Co), titanium (Ti), or the like. The film is formed above the semiconductor substrate 41 (on the side irradiated with light). The metal light shielding film 43 is opened at a position corresponding to the PD 31, and covers the semiconductor substrate 41 so as to shield the other portions. Thereby, the metal light shielding film 43 prevents, for example, generation of electrons in the memory unit 33 and the vicinity thereof, and prevents such electrons from flowing into the memory unit 33.

  The antireflection film 44 is a film made of, for example, silicon nitride (Si 3 N 4), and prevents light incident on the image sensor 11 from being reflected by the metal light shielding film 43. Note that the imaging element 11 may employ a configuration in which the antireflection film 44 is not formed.

  The wiring layer 45 is formed above the metal light shielding film 43 (on the side irradiated with light), and a plurality of wirings 52 constituting the horizontal signal line 22 and the vertical signal line 23 in FIG. Arranged to be in layers.

  Here, the metal light shielding film 43, the antireflection film 44, and the wiring layer 45 are formed with an opening 53 for providing an optical waveguide that propagates light incident from the surface side of the image sensor 11 to the PD 31. For example, the opening 53 is formed in a tapered shape so that the inner diameter is slightly narrowed from the surface side of the imaging element 11 toward the semiconductor substrate 41. As described later with reference to FIG. 4, the opening 53 has an inner diameter of the opening formed in the metal light shielding film 43 (for example, below the antireflection film 44). It is formed to be wider by a predetermined interval than the inner diameter of the opening at the end face.

  The passivation film 46 is formed so as to cover the surface of the wiring layer 45 and the inner side surface and the bottom surface of the opening 53. For example, the passivation film 46 is composed of a light-transmitting layer made of silicon nitride having a high refractive index formed by a CVD (Chemical Vapor Deposition) method or a sputtering method. Thus, by forming a material with low water permeability such as silicon nitride, it is possible to prevent moisture from entering the interlayer insulating film 51 from the opening of the optical waveguide and to improve element reliability.

  The light transmissive buried film 47 is formed so as to be embedded in the opening 53 where the passivation film 46 is formed and to be laminated on the surface of the passivation film 46. For example, the light transmissive buried film 47 may be made of silicon carbonitride (SiCN), silicon oxynitride (SiON), silicon carbide (SiC), silicon oxynitride (SiON), silicon nitride (SiN), acrylic or fluorine-based. A material having a high light transmittance such as a polymer, an organosilicon polymer siloxane, or polyaridene (PAr) is used. Moreover, it is preferable to use a resin (organic) material from the viewpoint of embedding.

  Accordingly, the passivation film 46 and the light transmissive buried film 47 are formed in two layers in the opening 53 such that the light transmissive buried film 47 serves as a core material and the passivation film 46 surrounds the outer periphery of the side surface of the light transmissive buried film 47. It is formed to be a structure. Further, the light-transmitting embedded film 47 is made of a material having a lower refractive index than that of the passivation film 46, and the light incident on the image sensor 11 is efficiently transmitted to the PD 31 in the opening 53 due to the difference in refractive index. An optical waveguide that propagates well is constructed. Note that the refractive index difference between the light transmissive buried film 47 and the passivation film 46 is not provided, and for example, the two layers of the light transmissive buried film 47 and the passivation film 46 are used as a core layer, and the refractive index is compared with these two layers. The optical waveguide may be configured by a difference in refractive index with the low interlayer insulating film 51.

  The planarizing film 48 is a film that planarizes the surface of the light transmissive buried film 47 in order to laminate the color filter layer 49. The color filter layer 49 includes a filter that transmits light of each color for each pixel 21 so that the PD 31 receives light of a predetermined color for each pixel 21. The on-chip lens layer 50 is configured by forming a small lens that collects the light irradiated to the image sensor 11 for each pixel 21.

  The imaging device 11 is configured in this way, and the light irradiated on the imaging device 11 is collected by the lens formed on the on-chip lens layer 50, passes through the color filter layer 49, and then passes through the opening 53. The light propagates through the optical waveguide formed by the passivation film 46 and the light transmissive buried film 47 and is received by the PD 31.

  Next, a manufacturing method of the image sensor 11 will be described with reference to the flowchart of FIG.

  First, in step S11, the base insulating film 42, the metal light shielding film 43, and the antireflection film 44 are sequentially formed on the entire surface of the semiconductor substrate 41 on which the PD 31 and the memory unit 33 are formed by ion implantation of impurities. Is done.

  In step S <b> 12, the wiring layer 45 is laminated on the antireflection film 44. That is, the process of forming the interlayer insulating film 51 with a predetermined thickness and forming the patterned wiring 52 on the surface is repeated a plurality of times, so that a plurality of wirings 52 are arranged between the interlayer insulating films 51. The provided wiring layer 45 is formed.

  In steps S13 and S14, an opening 53 is formed.

  First, in step S13, for example, the metal light shielding film 43 is used as an etching stopper, and the interlayer insulating film 51 and the antireflection film 44 of the wiring layer 45 are dry etched at a position corresponding to the location where the PD 31 is formed. To open.

  Next, in step S14, the metal light shielding film 43 is etched by self-alignment using openings formed in the interlayer insulating film 51 and the antireflection film 44 of the wiring layer 45, whereby the base insulating film 42 immediately above the PD 31 is etched. Until the opening 53 is formed. At this time, over-edge is performed so that the opening of the metal light-shielding film 43 recedes from the lower end of the opening formed in the interlayer insulating film 51 and the antireflection film 44.

  That is, as shown in FIG. 4, the opening 53 has an inner diameter of the opening formed in the metal light shielding film 43 (for example, below the wiring layer 45 or the antireflection film 44). It is formed to be wider than the inner diameter at the end face. That is, when the metal light shielding film 43 is opened, processing is performed so that the opening of the metal light shielding film 43 is wider in the radial direction at a predetermined interval W than the opening immediately above the metal light shielding film 43. The opening of the metal light shielding film 43 is formed so as to be within the region where the PD 31 is formed.

  In step S15, after the passivation film 46 is formed so as to cover the inner surface of the opening 53, in step S16, the light-transmitting embedded film 47 is embedded in the opening 53 in which the passivation film 46 is formed. As a result, an optical waveguide composed of the passivation film 46 and the light transmissive buried film 47 is formed inside the opening 53.

  Thereafter, the planarization film 48, the color filter layer 49, and the on-chip lens layer 50 are formed, and the imaging device 11 is manufactured.

  As described above, in the image sensor 11, after opening the interlayer insulating film 51 and the antireflection film 44 (step S13), etching is performed by self-alignment using the openings to open the metal light shielding film 43 (step S14). To do. For this reason, the position of the opening formed in the metal light-shielding film 43 is not shifted from the position of the opening formed thereabove, and an optical waveguide that propagates light to the PD 31 can be reliably formed.

  In addition, after opening the interlayer insulating film 51, the antireflection film 44, and the metal light shielding film 43 of the wiring layer 45, the metal light shielding film 43 is additionally subjected to lateral etching, thereby opening the metal light shielding film 43. You may employ | adopt the manufacturing method made to recede. Further, the opening of the metal light shielding film 43 may be retreated by isotropic dry etching or wet etching.

  Further, in the image pickup device 11, a process of forming the inner diameter of the opening formed in the metal light shielding film 43 wider than the inner diameter of the opening immediately above the metal light shielding film 43 (step S <b> 14) is higher than the metal light shielding film 43. An optical distance is provided between the optical waveguide and the metal light shielding film 43. In other words, by providing the interval W as shown in FIG. 4, it is possible to suppress the leakage light of light propagating through the optical waveguide from being reflected or absorbed by the metal light shielding film 43. Thereby, the loss of the light incident on the image sensor 11 can be suppressed, and as a result, the sensitivity characteristic of the image sensor 11 can be improved and the sensitivity can be further increased.

  For example, the loss of light energy in the optical waveguide will be described with reference to FIG.

  FIG. 5 shows the optical energy distribution in the depth direction (Z direction) immediately above the metal light-shielding film 43 with respect to the structural model of the optical waveguide configured as shown in FIG. 2 by the FDTD method (Finite Difference Time Domain method). : Finite region time difference method) shows the result obtained by calculation. FIG. 5 shows the refractive index immediately above the metal light-shielding film 43 in the optical waveguide configured as shown in FIG.

  In FIG. 5, the horizontal axis indicates the difference [nm] from the center of the optical waveguide in the YZ section of the image sensor 11 as the observation position of the light energy distribution. The vertical axis on the left side indicates a pointing vector Sz [a.u.] in which a physical quantity representing the energy flow density of the electromagnetic field is normalized, and the vertical axis on the right side indicates a refractive index.

  As described with reference to FIG. 2, the optical waveguide of the image sensor 11 uses the light-transmitting embedded film 47 as the optical waveguide core material, and the passivation film 46 surrounds the outer periphery of the side surface of the light-transmitting embedded film 47. It is formed as. Therefore, if the light-transmitting embedded film 47 has a refractive index nc and the passivation film 46 has a refractive index np, as shown in FIG. 5, the refractive index np higher than the refractive index nc is outside the region of the refractive index nc. The area is provided. Further, the region outside the passivation film 46 is a region shielded by the metal light shielding film 43, and for example, the refractive index of the interlayer insulating film 51 is shown.

  Further, as indicated by the pointing vector Sz in FIG. 5, the light energy distribution immediately above the metal light shielding film 43 is obtained, and the light energy corresponding to the tail is reflected or absorbed by the metal light shielding film 43. To lose.

  Therefore, by reducing the region where the light energy is lost by the metal light shielding film 43, that is, by forming the interval W by retracting the metal light shielding film 43 when forming the optical waveguide, the light energy can be reduced. Can be suppressed.

  Next, with reference to FIG. 6, the relationship between the light intensity inside the optical waveguide and the interval W will be described.

  In FIG. 6, the vertical axis indicates a value [au] in which the increase / decrease rate of the light intensity inside the optical waveguide is normalized, and the horizontal axis indicates the metal light shielding film with respect to the inner diameter of the opening directly above the metal light shielding film 43. The interval W between the inner diameters of the 43 openings is shown.

  FIG. 6 shows a change in light intensity (●) obtained by integrating the distribution of the pointing vector Sz shown in FIG. 4 and a change in light intensity (◯) obtained by the FDTD method. Has been. In addition, when calculating | requiring the intensity | strength of light by integrating the distribution of pointing vector Sz, it can respond to the increase in the space | interval W (retraction amount of the metal light shielding film 43) by increasing the integration area | region.

  As shown in FIG. 6, the light intensity obtained by these two methods similarly improves as the interval W for retreating the opening of the metal light shielding film 43 increases. From this, it can be said that the fluctuation of the sensitivity of the PD 31 is a loss due to the metal light shielding film 43. In this way, by providing the interval W, it is possible to suppress the loss of light incident on the image sensor 11, so that the image sensor 11 can have higher sensitivity.

  Here, conventionally, a silicon oxide film having a refractive index lower than that of the core material is formed by an anisotropic process before the formation of the silicon nitride film as the waveguide core material, so that the difference in the refractive index is generated in the optical waveguide. A technique has been used in which light is confined and light that has propagated through the optical waveguide is prevented from seeping into the metal light-shielding film. However, in the conventional measure against leakage light by the metal light shielding film, a silicon oxide film must be formed before the core material is embedded, and a silicon oxide film is also formed on the PD at the time of the film formation. It will be.

  Therefore, in the conventional structure, the reflectance of light is increased by adding an oxide film on the PD, and the sensitivity is lowered accordingly. There is also concern that the ripple will deteriorate. Furthermore, when the aspect ratio of the optical waveguide shape increases (optical waveguide having a height), the coverage of the silicon oxide film deteriorates. For this reason, if an attempt is made to form a film thickness sufficient to suppress the light leakage, the front end of the optical waveguide is filled, making it difficult to obtain the effect as an optical waveguide in the first place.

  On the other hand, in the image pickup device 11, by adopting the configuration of the optical waveguide as shown in FIG. 2, for example, there is no need to form an additional low refractive index layer on the optical waveguide. It is possible to avoid formation of a thick film. Thereby, in the image pick-up element 11, a reflectance can be reduced rather than the conventional structure in which such an excess film | membrane is formed, and the fall of a sensitivity and generation | occurrence | production of a ripple can be avoided. Thus, since the imaging device 11 can avoid a decrease in sensitivity, it is effective for a structure in which the aspect ratio of the optical waveguide is high or a miniaturized structure, such as a CMOS image sensor. That is, the structure of the optical waveguide of the image sensor 11 is an important structure from the viewpoint of improving sensitivity.

  In the optical waveguide of the image sensor 11, the opening formed in the metal light shielding film 43 is provided so as to be wider in the radial direction by a predetermined interval W than the opening immediately above the metal light shielding film 43. Alternatively, a structure in which a dielectric medium having a lower refractive index than that of the light transmissive buried film 47 may be employed in the region.

  That is, as shown in FIG. 7, a dielectric medium 61 having a lower refractive index than that of the light-transmitting buried film 47 is provided in a region provided by forming the opening formed in the metal light-shielding film 43 to be wide. It can be set as the structure which provided. Furthermore, the region where the dielectric medium 61 is provided may be a hollow layer. With such a configuration, a difference in refractive index between the interlayer insulating film 51 and the passivation film 46 can be increased, and light leakage can be more effectively suppressed.

  Further, the image pickup device 11 as described above is applied to various electronic devices such as an image pickup system such as a digital still camera or a digital video camera, a mobile phone having an image pickup function, or other devices having an image pickup function. can do.

  FIG. 8 is a block diagram illustrating a configuration example of an imaging device mounted on an electronic device.

  As shown in FIG. 8, the imaging apparatus 101 includes an optical system 102, an imaging element 103, a signal processing circuit 104, a monitor 105, and a memory 106, and can capture still images and moving images.

  The optical system 102 includes one or more lenses, guides image light (incident light) from the subject to the image sensor 103, and forms an image on the light receiving surface (sensor unit) of the image sensor 103.

  As the image sensor 103, the image sensor 11 having the above-described configuration example is applied. In the image sensor 103, electrons are accumulated for a certain period according to an image formed on the light receiving surface via the optical system 102. Then, a signal corresponding to the electrons accumulated in the image sensor 103 is supplied to the signal processing circuit 104.

  The signal processing circuit 104 performs various types of signal processing on the signal charges output from the image sensor 103. An image (image data) obtained by performing signal processing by the signal processing circuit 104 is supplied to the monitor 105 and displayed, or supplied to the memory 106 and stored (recorded).

  In the imaging apparatus 101 configured as described above, by applying the imaging element 11 having the above-described configuration example as the imaging element 103, an image with higher sensitivity characteristics can be obtained.

In addition, this technique can also take the following structures.
(1)
A semiconductor substrate on which a light receiving portion for generating electric charge in response to received light is formed;
A light-shielding film formed on the side irradiated with light to the semiconductor substrate;
A wiring layer formed on the light-irradiating side of the light shielding film;
In order to provide an optical waveguide that propagates light in the light receiving portion, the light shielding film and an opening formed in the wiring layer,
The opening is formed so that an opening formed in the light shielding film is wider in a radial direction by a predetermined interval than an opening immediately above the light shielding film.
(2)
The opening is formed by performing a process of opening the wiring layer by self-alignment using the light-shielding film as a stopper film, and performing an additional process of opening the light-shielding film. Imaging according to (1) element.
(3)
The imaging element according to (1) or (2), wherein after performing processing for opening the wiring layer and the light shielding film, the opening is formed by additionally performing processing for widening the opening of the light shielding film. .
(4)
A passivation film is formed on the side surface of the opening formed in the wiring layer, and a core material having a lower refractive index than that of the passivation film is embedded in the opening in which the passivation film is formed, whereby the optical waveguide is formed. The image pickup device according to any one of (1) to (3).
(5)
The opening formed in the light shielding film has a lower refractive index than the core material in a region provided by being formed so as to be wider in the radial direction by a predetermined interval than the opening immediately above the light shielding film. The imaging device according to (1), wherein a dielectric medium is provided.
(6)
A hollow layer is provided in a region provided by forming the opening formed in the light-shielding film so as to be wider in the radial direction by a predetermined interval than the opening immediately above the light-shielding film. The imaging device described in 1.

  Note that the present embodiment is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present disclosure.

  DESCRIPTION OF SYMBOLS 11 Image sensor, 12 Pixel array part, 13 Vertical drive part, 14 Column processing part, 15 Horizontal drive part, 16 Output part, 17 Drive control part, 21 Pixel, 22 Horizontal signal line, 23 Vertical signal line, 31 PD, 32 1st transfer transistor, 33 memory part, 34 2nd transfer transistor, 35 FD, 36 amplification transistor, 37 selection transistor, 38 reset transistor, 41 semiconductor substrate, 42 base insulating film, 43 metal light shielding film, 44 antireflection film , 45 wiring layer, 46 passivation film, 47 light transmissive buried film, 48 planarizing film, 49 color filter layer, 50 on-chip lens layer, 51 interlayer insulating film, 52 wiring, 53 opening

Claims (8)

A semiconductor substrate on which a light receiving portion for generating electric charge in response to received light is formed;
A light-shielding film formed on the side irradiated with light to the semiconductor substrate;
A wiring layer formed on the light-irradiating side of the light shielding film;
In order to provide an optical waveguide that propagates light in the light receiving portion, the light shielding film and an opening formed in the wiring layer,
The opening is formed so that an opening formed in the light shielding film is wider in a radial direction by a predetermined interval than an opening immediately above the light shielding film. The imaging element according to claim 1, wherein the opening is formed by performing a process of opening the wiring layer by self-alignment using the light-shielding film as a stopper film and additionally performing a process of opening the light-shielding film. . The imaging element according to claim 1, wherein after performing processing for opening the wiring layer and the light shielding film, the opening is formed by additionally performing processing for widening the opening of the light shielding film. A passivation film is formed on the side surface of the opening formed in the wiring layer, and a core material having a lower refractive index than that of the passivation film is embedded in the opening in which the passivation film is formed, whereby the optical waveguide is formed. The imaging device according to claim 1. The opening formed in the light shielding film has a lower refractive index than the core material in a region provided by being formed so as to be wider in the radial direction by a predetermined interval than the opening immediately above the light shielding film. The imaging device according to claim 4, wherein a dielectric medium is provided. The hollow layer is provided in a region provided by forming the opening formed in the light shielding film so as to be wider in the radial direction by a predetermined interval than the opening immediately above the light shielding film. The imaging device described. A light-shielding film is formed on the side on which light is irradiated to the semiconductor substrate on which the light-receiving portion that generates an electric charge according to the received light is formed,
Forming a wiring layer on the light-irradiating side of the light-shielding film;
Forming an opening in the light-shielding film and the wiring layer to provide an optical waveguide for propagating light in the light-receiving unit,
The method of manufacturing an image pickup device, wherein the opening is formed such that an opening formed in the light shielding film is wider in a radial direction by a predetermined interval than an opening immediately above the light shielding film. A semiconductor substrate on which a light receiving portion for generating electric charge in response to received light is formed;
A light-shielding film formed on the side irradiated with light to the semiconductor substrate;
A wiring layer formed on the light-irradiating side of the light shielding film;
In order to provide an optical waveguide for propagating light in the light receiving part, the light shielding film and an opening formed in the wiring layer,
The opening is formed such that an opening formed in the light-shielding film is wider in a radial direction by a predetermined interval than an opening immediately above the light-shielding film.

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