JP2013055252A - Solid state image sensor and manufacturing method therefor, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backside-illumination CMOS sensor which enhances photoelectric conversion efficiency.SOLUTION: An image sensor 11 comprises an organic photoelectric conversion layer 33 which is laminated on the light incident side of a semiconductor substrate 31. An organic photoelectric conversion film 43 is placed on the organic photoelectric conversion layer 33, and two PDs 41, 42 are placed on the semiconductor substrate 31. In the organic photoelectric conversion layer 33, a pair of transparent electrodes 54-1, 54-2 are provided to sandwich the organic photoelectric conversion film 43, the transparent electrode 54-1 on the semiconductor substrate 31 side is formed so as to have a curved surface protruding to the light incident side, and the organic photoelectric conversion film 43 is formed so as to have the shape of a curved surface copying the curved surface of the transparent electrode 54-1.

Description

  The present disclosure relates to a solid-state imaging device, a manufacturing method, and an electronic device, and more particularly, to a solid-state imaging device, a manufacturing method, and an electronic device that can improve photoelectric conversion efficiency.

  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.

  For example, incident light incident on a CMOS image sensor is photoelectrically converted in a PD (Photodiode) included in the pixel. Then, the charges generated in the PD are transferred to an FD (Floating Diffusion) via a transfer transistor, converted into a pixel signal having a level corresponding to the amount of received light in the FD, and read out.

  In general, in a solid-state imaging device, green, red, and blue pixels are arranged on a plane, and a pixel signal obtained by photoelectrically converting green, red, and blue light from each pixel is output. As an arrangement of each color, for example, a so-called Bayer arrangement in which one red pixel and one blue pixel are arranged for two green pixels can be cited.

  In such a solid-state imaging device, since only a single color signal is output from one pixel, for example, a demosaic process that complements blue and red pixel signals in green pixels from adjacent blue and red pixels Signal processing called is performed. However, with the demosaic process, image quality deterioration called false color may occur.

  Therefore, in order to avoid such deterioration of image quality due to false colors, the applicant of the present application stacked three photoelectric conversion layers in the vertical direction, and obtained a pixel signal obtained by photoelectrically converting three colors of light from one pixel. The solid-state image sensor to acquire is proposed (for example, refer patent document 1).

JP 2011-29337 A

  By the way, in the solid-state imaging device disclosed in Patent Document 1, the organic photoelectric conversion unit stacked on the semiconductor substrate has a lower photoelectric conversion rate than the inorganic photoelectric conversion unit formed inside the semiconductor substrate, It is required to improve the conversion efficiency in the organic photoelectric conversion part.

  This indication is made in view of such a situation, and makes it possible to aim at improvement in photoelectric conversion efficiency.

  A solid-state imaging device according to one aspect of the present disclosure includes a photoelectric conversion layer stacked on a light incident side with respect to a semiconductor substrate, and a plurality of photoelectric conversion units stacked along the light incident direction. And at least one of the photoelectric conversion portions arranged in the photoelectric conversion layer is formed to have a curved shape protruding toward the light incident side.

  A method for manufacturing a solid-state imaging device according to one aspect of the present disclosure includes: a photoelectric conversion layer stacked on a light incident side with respect to a semiconductor substrate; and a plurality of photoelectric conversion units stacked along the light incident direction And the one or more photoelectric conversion units arranged in the photoelectric conversion layer are formed with a curved shape protruding to the side on which the light is incident, A convex first electrode having a curved surface protruding toward the light incident side is formed on the photoelectric conversion layer, the photoelectric conversion unit is stacked following the curved surface of the first electrode, and the first Forming a second electrode that sandwiches the photoelectric conversion portion with the other electrode.

  An electronic device according to an aspect of the present disclosure includes a photoelectric conversion layer that is stacked on a light incident side with respect to a semiconductor substrate, and a plurality of photoelectric conversion units that are stacked along a direction in which the light is incident. The one or more photoelectric conversion units arranged in the photoelectric conversion layer include a solid-state imaging device formed to have a curved shape protruding toward the light incident side.

  In one aspect of the present disclosure, the photoelectric conversion unit disposed in the photoelectric conversion layer is formed to have a curved surface shape protruding toward the light incident side.

  According to one aspect of the present disclosure, it is possible to improve the photoelectric conversion efficiency.

It is a block diagram which shows the structural example of one Embodiment of the image pick-up element to which this invention is applied. It is a figure which shows the 1st structural example of a pixel. It is a figure which shows the 1st process in the manufacturing method of a 1st structural example. It is a figure which shows the 2nd process in the manufacturing method of a 1st structural example. It is a figure which shows the 3rd process in the manufacturing method of a 1st structural example. It is a figure which shows the 4th process in the manufacturing method of a 1st structural example. It is a figure which shows the 5th process in the manufacturing method of a 1st structural example. It is a figure which shows the 1st modification of the 1st structural example of a pixel. It is a figure which shows the 2nd modification of the 1st structural example of a pixel. It is a figure which shows the 2nd structural example of a pixel. It is a figure which shows the 11th process in the manufacturing method of the 2nd structural example. It is a figure which shows the 12th process in the manufacturing method of a 2nd structural example. It is a figure which shows the 13th process in the manufacturing method of the 2nd structural example. It is a figure which shows the 3rd structural example of a pixel. It is a figure which shows the 21st process in the manufacturing method of the 3rd structural example. It is a figure which shows the 22nd process in the manufacturing method of the 3rd structural example. It is a figure which shows the 23rd process in the manufacturing method of the 3rd structural example. It is a figure which shows the 24th process in the manufacturing method of the 3rd structural example. It is a figure which shows the 25th process in the manufacturing method of the 3rd structural example. It is a figure which shows the 26th process in the manufacturing method of the 3rd structural example. It is a figure which shows the 27th process in the manufacturing method of the 3rd structural example. It is a figure which shows the 4th structural example of a pixel. It is a figure which shows the 5th structural example of a pixel. 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 showing a configuration example of an embodiment of an image sensor to which the present invention is applied.

  As shown in FIG. 1, the image sensor 11 is a CMOS solid-state 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. Configured.

  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 the signal level of the pixel signal by performing CDS (Correlated Double Sampling) processing on the pixel signal output from each pixel 12 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 image 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.

  FIG. 2 is a cross-sectional view illustrating a configuration example of the imaging element 11, and FIG. 2 illustrates a first configuration example of the pixel 21.

  As shown in FIG. 2, the imaging element 11 is configured by laminating an insulating film 32 and an organic photoelectric conversion layer 33 on a semiconductor substrate 31. The image sensor 11 is a so-called back-illuminated CMOS sensor in which incident light is irradiated from the back surface opposite to the surface on which the wiring layer and the like are stacked on the semiconductor substrate 31.

  The semiconductor substrate 31 is configured by forming a thin SOI (Silicon on Insulator) layer 31b on the back side of an N-Epi (n-type epitaxial) layer 31a, and an insulating film 32 is laminated on the SOI layer 31b. Has been. The insulating film 32 is an insulating film formed of, for example, silicon dioxide (SiO 2), and insulates the semiconductor substrate 31 and the organic photoelectric conversion layer 33.

  The pixel 21 includes a PD 41 that photoelectrically converts blue light, a PD 42 that photoelectrically converts red light, and an organic photoelectric conversion film 43 that photoelectrically converts green light in the depth direction (along the light incident direction). A single pixel 21 can obtain a pixel signal obtained by photoelectrically converting three colors of light.

  That is, in the pixel 21, the organic photoelectric conversion layer 33 is formed on the organic photoelectric conversion film 43 in order from the back surface side (surface side facing upward in FIG. 2) irradiated with incident light, and the SOI layer of the semiconductor substrate 31. PD 41 is formed on 31 b, and PD 42 is formed on the N-Epi layer 31 a of the semiconductor substrate 31. Therefore, among the light irradiated to the pixels 21, green light is photoelectrically converted in the organic photoelectric conversion film 43, and among the light irradiated to the semiconductor substrate 31 through the organic photoelectric conversion film 43, blue light is Photoelectric conversion is performed in the PD 41, and red light is photoelectrically converted in the PD 42.

  Further, the pixel 21 includes a vertical electrode 44, an insulating film 45, an FD 46, an electrode 47, an FD 48, through electrodes 49 and 50, a charge accumulation region 51, an electrode 52, an FD 53, transparent electrodes 54-1 and 54-2, and A protective insulating film 55 is provided.

  The vertical electrode 44 is formed along the thickness direction (vertical direction) of the semiconductor substrate 31 so as to be in contact with the PD 41 from the surface side of the semiconductor substrate 31. The vertical electrode 44 is a gate electrode of a transfer transistor that transfers charges. By applying a predetermined voltage to the vertical electrode 44, the charge that is photoelectrically converted and accumulated in the PD 41 having a pn junction is stored. , And transferred to the FD 46.

  The insulating film 45 is formed so as to cover the outer periphery of the vertical electrode 44 and insulates the semiconductor substrate 31 from the vertical electrode 44.

  The FD 46 is disposed adjacent to the vertical electrode 44 so as to be in contact with the surface of the semiconductor substrate 31 and temporarily accumulates the charge transferred from the PD 41 via the transfer transistor. A gate electrode of an amplification transistor (not shown) is connected to the FD 46, and a pixel signal having a voltage corresponding to the level of charge accumulated in the FD 46 is output from the amplification transistor.

  The electrode 47 is disposed adjacent to the PD 42, and is formed at a position through an insulating film (not shown) with respect to the surface of the semiconductor substrate 31. The electrode 47 is a gate electrode of a transfer transistor that transfers charges. By applying a predetermined voltage to the electrode 47, the charges that are photoelectrically converted and accumulated in the PD 42 having a pn junction are transferred to the FD 48. Is done.

  The FD 48 is disposed adjacent to the PD 42 with the electrode 47 interposed therebetween, and is formed so as to contact the surface of the semiconductor substrate 31. The FD 48 temporarily accumulates charges transferred from the PD 42 via the transfer transistor.

  The through electrode 49 is formed so as to penetrate the semiconductor substrate 31 and the insulating film 32, one end of the through electrode 49 is connected to the transparent electrode 54-1 of the organic photoelectric conversion layer 33, and the other end of the through electrode 49 is Opened on the surface of the semiconductor substrate 31.

  The through electrode 50 is formed so as to penetrate the semiconductor substrate 31 and the insulating film 32, one end of the through electrode 50 is connected to the transparent electrode 54-2 of the organic photoelectric conversion layer 33, and the other end of the through electrode 50 is The charge storage region 51 formed on the surface side of the semiconductor substrate 31 is connected.

  The charge accumulation region 51 is formed so as to be in contact with the surface of the semiconductor substrate 31, and charges generated in the organic photoelectric conversion film 43 are supplied via the through electrode 50 and accumulates the charges.

  The electrode 52 is disposed adjacent to the charge storage region 51 and is formed at a position via an insulating film (not shown) with respect to the surface of the semiconductor substrate 31. The electrode 52 is a gate electrode of a transfer transistor that transfers charges. By applying a predetermined voltage to the electrode 52, charges accumulated in the charge accumulation region 51 are transferred to the FD 53.

  The FD 53 is disposed adjacent to the charge storage region 51 with the electrode 52 interposed therebetween, and is formed so as to contact the surface of the semiconductor substrate 31, and temporarily transfers the charge transferred from the charge storage region 51 via the transfer transistor. accumulate.

  The transparent electrodes 54-1 and 54-2 are transparent electrodes formed so as to sandwich the organic photoelectric conversion film 43 therebetween. The transparent electrode 54-1 is a lower electrode formed on the lower side of the organic photoelectric conversion film 43, and the transparent electrode 54-2 is an upper electrode formed on the upper side of the organic photoelectric conversion film 43.

  The transparent electrodes 54-1 and 54-2 are set to have a predetermined potential difference by a power source (not shown) through the through electrodes 49 and 50, whereby the charges generated in the organic photoelectric conversion film 43 are The charge is accumulated in the charge accumulation region 51 through the through electrode 50.

  The protective insulating film 55 is a film (passivation film) for protecting the organic photoelectric conversion film 43 and the transparent electrodes 54-1 and 54-2, and is applied to the entire surface of the imaging element 11.

  In the image sensor 11, the transparent electrode 54-1 has a convex curved surface (spherical surface or aspheric surface) that protrudes toward the light incident side (the upper side in FIG. 2) with respect to the back surface side of the image sensor 11. ). Thereby, the organic photoelectric conversion film 43 laminated following the curved surface of the transparent electrode 54-1 is formed to have a curved shape protruding toward the light incident side, and similarly, the transparent electrode 54-2 is also curved. It is formed with a shape.

  Therefore, in the image sensor 11, the surface area of the organic photoelectric conversion film 43 can be made wider than that of the conventional configuration in which the organic photoelectric conversion unit is formed in a planar manner. Thereby, since the light-receiving surface which receives light is expanded, the photoelectric conversion efficiency in the organic photoelectric conversion film 43 can be improved compared with the past. Moreover, in the image pick-up element 11, the contact area of the organic photoelectric converting film 43 and the transparent electrodes 54-1 and 54-2 can be made wider than the conventional structure, and also by this, the photoelectric conversion efficiency in the organic photoelectric converting film 43 Can be increased.

  Furthermore, in the image sensor 11, by having such a convex shape, the organic photoelectric conversion layer 33 can have a function as a convex lens that condenses incident light. Therefore, unlike the conventional case, it is not necessary to arrange an on-chip lens above the organic photoelectric conversion unit, and it is possible to collect light at a distance close to the PDs 41 and 42 (low profile), thereby improving the light collection efficiency. Can also be achieved at the same time.

  Next, with reference to FIGS. 3 to 7, a method for manufacturing the image sensor 11 including the pixels 21 will be described.

  As shown in FIG. 3, in the first step, PDs 41 and 42 are formed inside the semiconductor substrate 31 and thin film processing is performed from the surface side of the semiconductor substrate 31, and then FDs 46, 48, and 53, and charge An accumulation region 51 is formed. Further, after the vertical electrode 44, the insulating film 45, and the electrodes 47 and 52 are formed, the insulating film 32 is laminated on the back surface of the semiconductor substrate 31 to form the through electrodes 49 and 50.

  As shown in FIG. 4, in the second step, the transparent electrode 54-1 is formed so as to be laminated on the insulating film 32.

  First, the transparent electrode material constituting the transparent electrode 54-1 is formed on the entire surface of the insulating film 32. Examples of the transparent electrode material include indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (TO), and zinc oxide (ZnO). In particular, indium tin oxide or indium zinc oxide is preferably employed from the viewpoints of productivity, high conductivity, transparency, and the like. The transparent electrode material may be, for example, a sol-gel method, a spin coating method, a spray method, a roll coating method, an ion beam deposition method, an electron beam deposition method, or a laser ablation. The film can be formed using a method, a chemical vapor deposition method (CVD), a sputtering method, or the like.

  In addition, it is preferable to form using a sputtering method from a viewpoint of ensuring the uniformity and safety | security at the time of forming a transparent electrode material into a large area. For example, here, a transparent electrode material is formed by sputtering, and the refractive index is about 1.8 to 2.0. In addition, since the organic photoelectric conversion film 43 and the protective insulating film 55 are laminated in a later step and a convex lens is formed in the organic photoelectric conversion layer 33, the refractive index of these films is not greatly separated as much as possible. preferable.

  Next, the transparent electrode material formed on the entire surface of the insulating film 32 is patterned using a lithography technique, a dry etching technique, or the like, thereby forming a transparent electrode 54-1 having a convex shape on the upper side. Is done.

  Specifically, a photoresist pattern that is laminated on the transparent electrode material in a pattern that forms an island shape for each pixel 21 is formed, and the photoresist pattern is subjected to a heat treatment (reflow) to thereby form a photoresist pattern. Is processed into a substantially hemispherical convex pattern. Thereafter, etching is performed using the photoresist pattern having such a shape as a mask, thereby forming a transparent electrode 54-1 having a convex shape (melt method).

  As shown in FIG. 5, in the third step, an organic photoelectric conversion film material 43 ', a transparent electrode material 54'-2, and a resist 61 are laminated.

  The organic photoelectric conversion film material 43 ′ is a film formed of a material that becomes the organic photoelectric conversion film 43, and is formed over the entire surface of the transparent electrode 54-1 and the insulating film 32 by, for example, vapor deposition. As described above, the image sensor 11 is configured such that the organic photoelectric conversion film 43 photoelectrically converts green light. Examples of the organic photoelectric conversion film material 43 ′ include a rhodamine dye, a melocyanine dye, and quinacridone. An organic photoelectric conversion material containing can be employed.

  In the configuration where the organic photoelectric conversion film 43 photoelectrically converts red light, an organic photoelectric conversion material containing a phthalocyanine dye can be employed. Further, in the configuration in which the organic photoelectric conversion film 43 photoelectrically converts blue light, an organic photoelectric conversion material containing a coumarin dye, tris-8-hydroxyquinoline Al (Alq3), a melocyanine dye, or the like is employed. be able to.

  Further, for example, an organic co-deposition film that is a composite film of organic semiconductors formed by simultaneously depositing two or more kinds of organic semiconductors (p-type organic semiconductor and n-type organic semiconductor) on the same substrate is used as a photoelectric conversion material. Can also be used. Such an organic co-deposited film is a material capable of obtaining high photoelectric conversion efficiency as compared with a single layer organic photoelectric conversion film. For example, non-patent literature “M. Hiramoto, H. Fujiwara, and M Yokoyama, Applied Physics Letters, 58, 1062 (1991).

  In addition, the p-type organic semiconductor has the above-described quinacridone pigment (DQ), phthalocyanine pigment and derivatives thereof (MPc having various metals at the center, H2Pc without metal, and various substituents around it. Etc.), porphyrins, melocyanins, etc. and their derivatives can be employed. On the other hand, as an n-type organic semiconductor, various perylene pigments and derivatives thereof (derivatives having different substituents attached to nitrogen atoms are known, for example, t-BuPh-PTC, PhEt-PTC, etc., and high photoelectric conversion. Im-PTC having an ability may be used), naphthalene derivatives (perylene skeleton of perylene pigment is naphthalene, for example, NTCDA), C60, and the like.

  In addition, in order to obtain the condensing effect as a convex lens in the organic photoelectric conversion film 43, the organic photoelectric conversion film material 43 ′ is a material that does not have a large difference in refractive index from the transparent electrodes 54-1 and 54-2 ( It is preferable to employ a refractive index difference of about 0 to 0.4. Specifically, for example, quinacridone (refractive index: 1.7 to 2.0) is preferably used as the organic photoelectric conversion film material 43 ′.

  The transparent electrode material 54'-2 is a film made of a material that becomes the transparent electrode 54-2, and is formed on the organic photoelectric conversion film material 43 '. As the transparent electrode material 54'-2, for example, indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (TO), zinc oxide (ZnO), or the like can be employed. In particular, indium tin oxide or indium zinc oxide is preferably employed from the viewpoints of productivity, high conductivity, transparency, and the like. Further, the transparent electrode material 54'-2 can be formed by, for example, a sputtering method.

  The resist 61 is formed in accordance with the regions left as the organic photoelectric conversion film 43 and the transparent electrode 54-2 after the organic photoelectric conversion film material 43 'and the transparent electrode material 54'-2 are formed.

  As shown in FIG. 6, in the fourth step, the structure formed in the third step is subjected to, for example, dry etching so that the organic photoelectric conversion film in the region where the resist 61 is not formed. Material 43 'and transparent electrode material 54'-2 are removed. Thereby, the organic photoelectric conversion film 43 and the transparent electrode 54-2 are patterned simultaneously.

  As shown in FIG. 7, in the fifth step, the resist 61 is removed. At this time, the through electrode 50 is extended so as to be in contact with the transparent electrode 54-2.

  Thereafter, as shown in FIG. 2, a protective insulating film 55 is formed by, for example, a CVD method. The protective insulating film 55 needs to have a refractive index of 0.6 or more, that is, 1.6 or more with respect to the refractive index of air of about 1.0, in order to obtain good light condensing with the air directly touched. Furthermore, considering the refractive index of the organic photoelectric conversion film 43 formed below the protective insulating film 55, the protective insulating film 55 is equivalent to the refractive index of the film constituting the organic photoelectric conversion film 43, or It is preferable to employ a film having a refractive index within +0.3. For example, as the protective insulating film 55, it is appropriate to employ a silicon nitride film having a refractive index of about 2.1, a silicon oxynitride film having a refractive index of about 1.8, or the like.

  As described above, it is preferable that the organic photoelectric conversion film 43, the transparent electrodes 54-1 and 54-2, and the protective insulating film 55 constituting the organic photoelectric conversion layer 33 have no significant difference in refractive index. The difference is set within 0.4, for example.

  Furthermore, in the organic photoelectric conversion layer 33, it is preferable to select a material having a higher refractive index from a lower one in order from the upper side to the lower side as materials adjacent to each other. As a selection example, for example, for the protective insulating film 55 and the transparent electrode 54-2, SiN (refractive index: about 2.1) is selected as the protective insulating film 55, and ITO (refractive index: 1.8 to 2.0, film formation> condition (refractive index: 2.0 by adjusting O2 content adjustment), or GZO (refractive index: 1.9) is selected. As for the transparent electrode 54-2 and the organic photoelectric conversion film 43, ITO (refractive index: 2.0) or GZO (refractive index: 1.9) is selected as the transparent electrode 54-2, and quinacridone (refractive index) is selected as the organic photoelectric conversion film 43. Ratio: 1.9 to 2.0) is selected. As for the organic photoelectric conversion film 43 and the transparent electrode 54-1, quinacridone (refractive index: 1.9 to 2.0) is selected as the organic photoelectric conversion film 43, and ITO (refractive index: 1.8) is selected as the transparent electrode 54-1. Is done. For the transparent electrode 54-1 and the insulating film 32, ITO (1.8) is selected as the transparent electrode 54-1, and SiO2 (refractive index: 1.45) is selected as the insulating film 32.

  The manufacturing process of the image sensor 11 is completed through the above steps. In the manufacturing process described above, the organic photoelectric conversion film 43 and the transparent electrode 54-2 are simultaneously patterned by a dry etching technique. For example, the organic photoelectric conversion film 43 and the transparent electrode 54-2 are patterned using a lithography technique. May be simultaneously patterned.

  Next, FIG. 8 shows a first modification of the first configuration example of the pixel 21.

  The pixel 21 ′ shown in FIG. 8 has a different configuration from the pixel 21 of FIG. 2 in that a convex portion 32 a is formed on the insulating film 32. That is, in the pixel 21 of FIG. 2, the insulating film 32 is formed in a planar manner, whereas in the pixel 21 ′, the insulating film 32 is formed to have a convex curved surface. The pixel 21 ′ has a configuration that is common to the pixel 21 in other points, and a detailed description of the common configuration is omitted.

  The convex portion 32 a is formed of silicon dioxide (SiO 2), for example, like the insulating film 32. That is, the convex portion 32a is formed so that a part of the back surface of the insulating film 32 protrudes toward the back surface side (the light incident side) in the central region of the pixel 21 '.

  Thus, the pixel 21 ′ employs a configuration in which the convex portion 32a is formed in the insulating film 32 and the transparent electrode 54-1 is formed following the curved surface of the convex portion 32a. Even in such a configuration, the photoelectric conversion efficiency can be improved similarly to the pixel 21 in FIG.

  Next, FIG. 9 shows a second modification of the first configuration example of the pixel 21.

  The pixel 21 ″ shown in FIG. 9 is different from the pixel 21 ′ in FIG. 8 in that a convex member 32 b is provided between the semiconductor substrate 31 and the insulating film 32. Note that the pixel 21 ″ has the same configuration as the pixel 21 ′ in other respects, and a detailed description of the common configuration is omitted.

  The convex member 32b is formed of, for example, silicon dioxide (SiO2), for example, like the insulating film 32. In the central region of the pixel 21 '', the convex member 32b has a convex curved surface protruding toward the back side. It is provided on the back side of the substrate 31. By forming the convex member 32b, when forming the insulating film 32, the shape of the convex member 32b is transferred to the insulating film 32 to form the convex portion 32a.

  Thus, in the pixel 21 ″, a configuration in which the convex member 32b is formed so as to be stacked on the semiconductor substrate 31 and the transparent electrode 54-1 is formed following the curved surface of the convex portion 32a is employed. I keep it. Even in such a configuration, the photoelectric conversion efficiency can be improved similarly to the pixel 21 in FIG.

  Next, FIG. 10 shows a second configuration example of the pixel 21.

  The pixel 21A shown in FIG. 10 has a different configuration from the pixel 21 in FIG. 2 in that an organic photoelectric conversion film 71 that photoelectrically converts blue light is provided in the organic photoelectric conversion layer 33A. That is, in the pixel 21, blue light is photoelectrically converted in the PD 41 formed on the semiconductor substrate 31, whereas in the pixel 21A, an organic photoelectric conversion film 71 is provided instead of the PD 41, and the organic photoelectric conversion film is provided. In 71, the blue light is photoelectrically converted. Hereinafter, a detailed description of the configuration common to the pixel 21 will be omitted as appropriate.

  In the organic photoelectric conversion layer 33A, a transparent electrode 54-1, an organic photoelectric conversion film 71, a transparent electrode 54-2, an organic photoelectric conversion film 43, a transparent electrode 54-3, and a protective insulating film 55 are stacked in this order from the bottom. Has been configured.

  The transparent electrodes 54-1 and 54-2 are configured to sandwich the organic photoelectric conversion film 71, and the through electrode 72 connected to the transparent electrode 54-1 and the through electrode 49 connected to the transparent electrode 54-2 are provided. Through this, a predetermined potential difference is set. Then, the charges generated in the organic photoelectric conversion film 71 are accumulated in the charge accumulation region 73 through the through electrode 72 connected to the transparent electrode 54-1. Further, the charge accumulated in the charge accumulation region 73 is transferred to the FD 46 via the electrode 74 which is the gate electrode of the transfer transistor.

  Further, the transparent electrodes 54-2 and 54-3 are configured to sandwich the organic photoelectric conversion film 43 therebetween. The transparent electrode 54-2 is shared by the organic photoelectric conversion film 43 and the organic photoelectric conversion film 71, and is connected to, for example, GND. The charges generated in the organic photoelectric conversion film 43 are accumulated in the charge accumulation region 51 through the through electrode 50 connected to the transparent electrode 54-3.

  As described above, the pixel 21A is configured by stacking the organic photoelectric conversion film 43, the organic photoelectric conversion film 71, and the PD 42. In one pixel 21A, a pixel obtained by photoelectrically converting green, blue, and red light. A signal can be output. In the pixel 21A, similarly to the pixel 21, the areas of the organic photoelectric conversion films 43 and 71 can be made wider than the planar configuration, and the photoelectric conversion efficiency can be improved.

  Next, with reference to FIG. 11 to FIG. 13, a method for manufacturing the image sensor 11 including the pixel 21 </ b> A will be described.

  First, similar to the first to fifth steps described with reference to FIGS. 3 to 7, the transparent electrode 54-1, the organic photoelectric conversion film 71, and the transparent electrode are formed on the semiconductor substrate 31A and the insulating film 32A. A structure in which 54-2 is laminated is manufactured.

  As shown in FIG. 11, in the eleventh step, the organic photoelectric conversion film material 43 ', the transparent electrode material 54'-3, and the resist 61 are laminated in the same manner as in the third step.

  As shown in FIG. 12, in the twelfth step, the organic photoelectric conversion film material 43 ′ and the transparent electrode in the region where the resist 61 is not formed by performing dry etching in the same manner as the fourth step described above. Material 54'-3 is removed. Thereby, the organic photoelectric conversion film 43 and the transparent electrode 54-3 are simultaneously patterned.

  As shown in FIG. 13, in the thirteenth step, the resist 61 is removed as in the fifth step described above. At this time, the through electrode 50 is extended so as to be in contact with the transparent electrode 54-3.

  Thereafter, as shown in FIG. 10, the protective insulating film 55 is formed by, for example, the CVD method, and the manufacturing process of the image sensor 11 including the pixels 21 </ b> A is completed.

  Next, FIG. 14 shows a third configuration example of the pixel 21.

  The pixel 21B shown in FIG. 14 includes an organic photoelectric conversion film 71 that photoelectrically converts blue light and an organic photoelectric conversion film 81 that photoelectrically converts red light in the organic photoelectric conversion layer 33B. The configuration is different from that of the pixel 21 in FIG. That is, in the pixel 21, blue and red light are photoelectrically converted in the PDs 41 and 42 formed on the semiconductor substrate 31, whereas in the pixel 21 </ b> B, the organic photoelectric conversion films 71 and 81 are replaced with the PDs 41 and 42. Is provided. In the pixel 21 </ b> B, blue light is photoelectrically converted in the organic photoelectric conversion film 71, and red light is photoelectrically converted in the organic photoelectric conversion film 81. Hereinafter, a detailed description of the configuration common to the pixel 21 will be omitted as appropriate.

  In the organic photoelectric conversion layer 33B, in order from the bottom, the transparent electrode 54-1, the organic photoelectric conversion film 71, the transparent electrode 54-2, the organic photoelectric conversion film 43, the transparent electrode 54-3, the interlayer insulating film 82, and the transparent electrode 54 are provided. -4, the organic photoelectric conversion film 81, the transparent electrode 54-5, and the protective insulating film 55 are laminated.

  The transparent electrodes 54-1 and 54-2 are configured to sandwich the organic photoelectric conversion film 71, and the through electrode 72 connected to the transparent electrode 54-1 and the through electrode 49 connected to the transparent electrode 54-2 are provided. Through this, a predetermined potential difference is set. Then, the charges generated in the organic photoelectric conversion film 71 are accumulated in the charge accumulation region 73 through the through electrode 72 connected to the transparent electrode 54-1. Further, the charge accumulated in the charge accumulation region 73 is transferred to the FD 46 via the electrode 74 which is the gate electrode of the transfer transistor.

  Further, the transparent electrodes 54-2 and 54-3 are configured to sandwich the organic photoelectric conversion film 43 therebetween. The transparent electrode 54-2 is shared by the organic photoelectric conversion film 43 and the organic photoelectric conversion film 71, and is connected to, for example, GND. The charges generated in the organic photoelectric conversion film 43 are accumulated in the charge accumulation region 51 through the through electrode 50 connected to the transparent electrode 54-3.

  The transparent electrodes 54-4 and 54-5 are configured to sandwich the organic photoelectric conversion film 81, and a through electrode 83 connected to the transparent electrode 54-4 and a through electrode 84 connected to the transparent electrode 54-5 are provided. Through this, a predetermined potential difference is set. The charges generated in the organic photoelectric conversion film 81 are accumulated in the charge accumulation region 85 through the through electrode 84 connected to the transparent electrode 54-5. Further, the charge accumulated in the charge accumulation region 85 is transferred to the FD 46 via the electrode 74 which is the gate electrode of the transfer transistor.

  As described above, the pixel 21B is configured by stacking the organic photoelectric conversion film 81, the organic photoelectric conversion film 43, and the organic photoelectric conversion film 71. In one pixel 21B, green, blue, and red light is emitted. A photoelectrically converted pixel signal can be output. Further, in the pixel 21B, similarly to the pixel 21, the areas of the organic photoelectric conversion films 43, 71, and 81 can be made wider than the planar configuration, and the photoelectric conversion efficiency can be improved.

  Next, with reference to FIGS. 15 to 21, a method for manufacturing the image sensor 11 including the pixel 21 </ b> B will be described.

  First, similarly to the first to fifth steps described with reference to FIGS. 3 to 7 and the eleventh to thirteenth steps described with reference to FIGS. A structure in which the transparent electrode 54-1, the organic photoelectric conversion film 71, the transparent electrode 54-2, the organic photoelectric conversion film 43, and the transparent electrode 54-3 are laminated on the film 32B is manufactured.

  As shown in FIG. 15, in the twenty-first process, an interlayer insulating film material 82 'that is a material of the interlayer insulating film 82 is formed.

  As shown in FIG. 16, in the twenty-second process, a transparent electrode material 54'-4 that is a material of the transparent electrode 54-4 is formed on the interlayer insulating film material 82 '.

  As shown in FIG. 17, in the twenty-third process, a resist 61 is formed in accordance with the regions left as the interlayer insulating film 82 and the transparent electrode 54-4.

  As shown in FIG. 18, in the 24th step, dry etching is performed to remove the interlayer insulating film material 82 'and the transparent electrode material 54'-4 in the region where the resist 61 is not formed. Thereby, the interlayer insulating film 82 and the transparent electrode 54-4 are patterned simultaneously.

  As shown in FIG. 19, in the 25th step, the resist 61 is removed. At this time, the through electrode 83 is extended so as to be in contact with the transparent electrode 54-4.

  As shown in FIG. 20, in the twenty-sixth step, the organic photoelectric conversion film material 81 ', the transparent electrode material 54'-5, and the resist 61 are stacked in the same manner as in the third step.

  As shown in FIG. 21, in the 27th step, dry etching is performed to remove the organic photoelectric conversion film material 81 'and the transparent electrode material 54'-5 in the region where the resist 61 is not formed. Thereby, the organic photoelectric conversion film 81 and the transparent electrode 54-5 are simultaneously patterned, and then the resist 61 is removed.

  Thereafter, as shown in FIG. 14, the protective insulating film 55 is formed by, for example, the CVD method, and the manufacturing process of the imaging device 11 including the pixel 21 </ b> B is completed.

  Next, FIG. 22 shows a fourth configuration example of the pixel 21.

  The pixel 21C shown in FIG. 22 is different from the pixel 21 in FIG. 2 in that a light shielding film 91 is formed on the insulating film 32. In other points, the pixel 21C is different from the pixel 21 in FIG. The configuration is common. Hereinafter, a detailed description of the configuration common to the pixel 21 will be omitted as appropriate.

  The light shielding film 91 suppresses leakage of light incident in an oblique direction with respect to the PDs 41 and 42 formed inside the semiconductor substrate 31. Moreover, pupil correction can be easily performed using the light shielding film 91.

  Here, in the conventional solid-state imaging device, for example, in the solid-state imaging device disclosed in Patent Document 1 described above, the on-chip lens is disposed above the organic photoelectric conversion film. It is necessary to arrange light shielding films between the photoelectric conversion films and at two places (two layers) between the organic photoelectric conversion film and the PD, and to perform pupil correction in each of the light shielding films.

  On the other hand, in the pixel 21 </ b> C, the organic photoelectric conversion layer 33 itself has a function as an on-chip lens, so that only the PDs 41 and 42 formed in the semiconductor substrate 31 are subject to pupil correction. . Therefore, it is only necessary to provide the light shielding film 91 between the organic photoelectric conversion film 43 and the PD 41, and pupil correction may be performed on only one light shielding film 91. Accordingly, the pupil correction can be easily performed as compared with the case where the pupil correction is performed at two locations.

  In particular, in a configuration having an organic photoelectric conversion unit and an inorganic photoelectric conversion unit (PD), since three color photoelectric conversion units are provided in the vertical direction, the three color photoelectric conversion units are arranged in a plane (for example, a Bayer array). It is assumed that it is not easy to perform pupil correction so as to suppress vignetting for any photoelectric conversion unit as compared to the configuration described above. It is also assumed that the shrink rate for pupil correction will be high.

  Therefore, the fact that the subject of pupil correction is two pixels depending on the structure of the image sensor 11 makes it possible to perform pupil correction relatively easily and form a highly sensitive element. Furthermore, since the shrinkage ratio can be lowered, it is more preferable from the viewpoint of miniaturizing the element.

  Next, FIG. 23 illustrates a fifth configuration example of the pixel 21.

  The pixel 21D shown in FIG. 23 is configured differently from the pixel 21 of FIG. 2 in that a thin film buffer film 92 is inserted between the organic photoelectric conversion film 43 and the transparent electrode 54-1. In other respects, the configuration is the same as that of the pixel 21 in FIG. Hereinafter, a detailed description of the configuration common to the pixel 21 will be omitted as appropriate.

  The thin film buffer film 92 is a thin film having a thickness of about several nanometers. By inserting the thin film buffer film 92, the electrical characteristics (dark current suppression, photocurrent improvement, etc.) of the organic photoelectric conversion film 43 are improved. Can do. As the thin-film buffer film 92, for example, Batocuproine (BCP) (refractive index: about 1.7) can be adopted as an organic film. In addition, as an inorganic film, tantalum oxide (Ta2O5) (refractive index: 2.0 to 2.2), hafnium oxide (HfO2) (refractive index 1.9 to 2.2), titanium oxide (TiO2) (refractive index: 2.2 to 2.5), etc. A material having a refractive index of 1.6 or more and 2.2 or less can be used.

  As shown in FIG. 23, a thin film buffer 92 is inserted between the organic photoelectric conversion film 43 and the transparent electrode 54-1, and a thin film buffer is interposed between the organic photoelectric conversion film 43 and the transparent electrode 54-2. A membrane (not shown) may be inserted. A thin film buffer film 92 is inserted between the organic photoelectric conversion film 43 and the transparent electrode 54-1, and a thin film buffer film (not shown) is interposed between the organic photoelectric conversion film 43 and the transparent electrode 54-2. May be inserted.

  The imaging device 11 having the above-described configuration is, for example, an electronic system such as an imaging system such as a digital still camera or a digital video camera, a mobile phone having an imaging function, or another device having an imaging function. Can be applied to.

  FIG. 24 is a block diagram illustrating a configuration example of an imaging device mounted on an electronic device.

  As shown in FIG. 24, 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 of each configuration example as described above 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 of each configuration example as described above as the imaging element 103, photoelectric conversion can be performed even with a small amount of light, and noise is reduced and better. Can be obtained.

  Further, the imaging device 11 according to the present technology can be employed in a front-illuminated CMOS solid-state imaging device, a CCD solid-state imaging device, and the like in addition to a back-illuminated CMOS solid-state imaging device.

In addition, this technique can also take the following structures.
(1)
A photoelectric conversion layer stacked on the light incident side with respect to the semiconductor substrate;
A plurality of photoelectric conversion units stacked along the direction in which the light is incident,
One or more said photoelectric conversion parts arrange | positioned at the said photoelectric converting layer are formed with the curved surface shape which protrudes in the side into which the said light enters. Solid-state image sensor.
(2)
The plurality of photoelectric conversion units respectively photoelectrically convert light of a predetermined color,
Of the plurality of photoelectric conversion units, the photoelectric conversion unit that photoelectrically converts light of a color other than the color of light that is photoelectrically converted in the photoelectric conversion unit disposed in the photoelectric conversion film is provided inside the semiconductor substrate. The solid-state imaging device according to (1), which is disposed in
(3)
The photoelectric conversion unit disposed in the photoelectric conversion film is an organic photoelectric conversion unit in which an organic photoelectric conversion material is used,
The solid-state imaging device according to (1) or (2), wherein the photoelectric conversion unit disposed inside the semiconductor substrate is an inorganic photoelectric conversion unit having a pn junction.
(4)
The photoelectric conversion part disposed on the photoelectric conversion film uses an organic co-deposition film that is a composite film formed by simultaneously depositing two or more types of organic semiconductors. (1) to (3) The solid-state imaging device according to any one of the above.
(5)
Between the said photoelectric converting layer and the said semiconductor substrate, the light shielding film which light-shields the said light incident from the diagonal direction with respect to the photoelectric conversion part arrange | positioned inside the said semiconductor substrate is arrange | positioned from said (1) ( The solid-state imaging device according to any one of 4).
(6)
The photoelectric conversion layer has at least a pair of electrodes that sandwich the photoelectric conversion unit disposed in the photoelectric conversion layer,
The electrode that sandwiches the photoelectric conversion unit from the semiconductor substrate side is formed in a convex shape having a curved surface protruding to the light incident side, and the photoelectric conversion unit is stacked following the curved surface of the electrode The solid-state imaging device according to any one of (1) to (5) above.
(7)
A protective insulating film stacked on the electrode that sandwiches the photoelectric conversion unit from the light incident side;
The solid-state imaging device according to (6), wherein a difference in refractive index between each of the photoelectric conversion unit, the electrode, and the protective insulating film disposed in the photoelectric conversion layer is set to a predetermined value or less. .
(8)
Further comprising an insulating film laminated between the semiconductor substrate and the photoelectric conversion layer;
The solid-state imaging device according to any one of (1) to (7), wherein a convex portion that protrudes toward the light incident side is formed on a surface of the insulating film on the photoelectric conversion film side.
(9)
The solid-state imaging device according to (8), wherein a convex member that protrudes toward the light incident side is provided between the insulating film and the semiconductor substrate.

  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 Semiconductor substrate, 32 insulating film, 32a convex part, 32b convex member, 33 organic photoelectric conversion layer, 41 and 42 PD, 43 organic photoelectric conversion film, 44 vertical electrode, 45 insulating film, 46 FD, 47 electrode, 48 FD, 49 And 50 through electrode, 51 charge storage region, 52 electrode, 53 FD, 54-1 and 54-2 transparent electrode, 55 protective insulating film

Claims (11)

A photoelectric conversion layer stacked on the light incident side with respect to the semiconductor substrate;
A plurality of photoelectric conversion units stacked along the direction in which the light is incident,
One or more said photoelectric conversion parts arrange | positioned at the said photoelectric converting layer are formed with the curved surface shape which protrudes in the side into which the said light enters. Solid-state image sensor. The plurality of photoelectric conversion units respectively photoelectrically convert light of a predetermined color,
Of the plurality of photoelectric conversion units, the photoelectric conversion unit that photoelectrically converts light of a color other than the color of light that is photoelectrically converted in the photoelectric conversion unit disposed in the photoelectric conversion film is provided inside the semiconductor substrate. The solid-state imaging device according to claim 1, wherein The photoelectric conversion unit disposed in the photoelectric conversion film is an organic photoelectric conversion unit in which an organic photoelectric conversion material is used,
The solid-state imaging device according to claim 2, wherein the photoelectric conversion unit disposed inside the semiconductor substrate is an inorganic photoelectric conversion unit having a pn junction. The solid-state imaging device according to claim 2, wherein an organic co-deposition film that is a composite film formed by simultaneously depositing two or more kinds of organic semiconductors is used for the photoelectric conversion unit disposed in the photoelectric conversion film. . The light shielding film which shields the said light which injects from the diagonal direction with respect to the photoelectric conversion part arrange | positioned inside the said semiconductor substrate between the said photoelectric converting layer and the said semiconductor substrate is arrange | positioned. Solid-state image sensor. The photoelectric conversion layer has at least a pair of electrodes that sandwich the photoelectric conversion unit disposed in the photoelectric conversion layer,
The electrode that sandwiches the photoelectric conversion unit from the semiconductor substrate side is formed in a convex shape having a curved surface protruding to the light incident side, and the photoelectric conversion unit is stacked following the curved surface of the electrode The solid-state imaging device according to claim 1. A protective insulating film stacked on the electrode that sandwiches the photoelectric conversion unit from the light incident side;
The solid-state imaging device according to claim 6, wherein a difference in refractive index among each of the photoelectric conversion unit, the electrode, and the protective insulating film arranged in the photoelectric conversion layer is set to a predetermined value or less. Further comprising an insulating film laminated between the semiconductor substrate and the photoelectric conversion layer;
The solid-state imaging device according to claim 1, wherein a convex portion protruding to the light incident side is formed on a surface of the insulating film on the photoelectric conversion film side. The solid-state imaging device according to claim 8, wherein a convex member that protrudes toward the light incident side is provided between the insulating film and the semiconductor substrate. 1 having a photoelectric conversion layer stacked on a light incident side of a semiconductor substrate and a plurality of photoelectric conversion portions stacked along a direction in which the light is incident, and disposed on the photoelectric conversion layer In the method of manufacturing a solid-state imaging device, the photoelectric conversion unit described above is formed with a curved surface protruding to the light incident side.
On the photoelectric conversion layer, a convex first electrode having a curved surface protruding on the light incident side is formed,
Laminating the photoelectric conversion unit following the curved surface of the first electrode,
The manufacturing method including the step of forming the 2nd electrode which pinches | interposes the said photoelectric conversion part between said 1st electrodes. A photoelectric conversion layer stacked on the side on which light is incident on the semiconductor substrate;
A plurality of photoelectric conversion units stacked along the direction in which the light is incident, and
One or more said photoelectric conversion parts arrange | positioned at the said photoelectric converting layer are formed with the curved surface shape which protrudes in the side into which the said light enters. Electronic equipment provided with the solid-state image sensor.

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