JP2014022649A - Solid-state image sensor, imaging device, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve imaging performance.SOLUTION: A solid-state image sensor (1) comprises: a light receiving layer (32) including photoelectric conversion units (15) respectively arranged for pixels (3) that are two-dimensionally arrayed; a lens layer (36) including lens elements (49) for focusing light on the photoelectric conversion units; a wiring layer (34) disposed between the lens layer and the light receiving layer, and including wires (43) to (45) which are electrically connected with a circuit for reading out an electric charge from the photoelectric conversion units; and an intermediate layer (35) disposed between the wiring layer and the lens layer. The intermediate layer includes: pixel center portions (50) which overlap with the centers of the photoelectric conversion units when viewed from a thickness direction of the light receiving layer; and pixel peripheral edge portions (51) arranged in at least parts of peripheries of the pixel center portions when viewed from the thickness direction of the light receiving layer, and having a refractive index higher than that of the pixel center portions.

Description

  The present invention relates to a solid-state imaging device, an imaging apparatus, and an electronic apparatus.

  Solid-state imaging devices such as a CCD type and a CMOS type are used in electronic devices such as an imaging device such as a camera and a measuring device that measures a shape and a position (for example, see Patent Document 1 below). The solid-state imaging device includes a photodiode disposed in each of a plurality of pixels, a microlens that collects light on the photodiode of each pixel, and the like.

JP 2012-28585 A

  In the solid-state imaging device as described above, a part of the light collected by the microlens may not be incident on the photodiode of the pixel due to, for example, vignetting caused by wiring or the like. In addition, part of the light collected by the microlens may enter the photodiode of the adjacent pixel. In particular, when a bright lens is used as a microlens in order to obtain a bright image, the spread angle of light emitted from the microlens is increased, making it difficult to enter a desired photodiode. As a result, there is a possibility that the imaging performance is degraded. The present invention has been made in view of the above circumstances, and an object thereof is to improve imaging performance.

  The solid-state imaging device according to the first aspect of the present invention includes a light receiving layer including a photoelectric conversion unit that converts light into electric power, a lens layer including a lens element that collects light on the photoelectric conversion unit, and the lens layer. A wiring layer disposed between the light receiving layer and including a wiring electrically connected to a circuit for reading out charges from the photoelectric conversion unit, and an intermediate disposed between the wiring layer and the lens layer A middle portion of the pixel that overlaps the center of the photoelectric conversion unit when viewed from the thickness direction of the light receiving layer, and at least a periphery of the central portion of the pixel when viewed from the thickness direction of the light receiving layer. A pixel peripheral portion that is disposed in part and has a higher refractive index than the pixel central portion.

  The solid-state imaging device according to the second aspect of the present invention is a back-illuminated solid-state imaging device, and includes a light receiving layer including a photoelectric conversion unit that converts light into electric power, and a lens that collects light on the photoelectric conversion unit. A lens layer including an element, and an intermediate layer disposed between the light receiving layer and the lens layer, and the intermediate layer overlaps a center of the photoelectric conversion unit when viewed from a thickness direction of the light receiving layer. A pixel central portion, and a pixel peripheral portion that is disposed at least at a part of the periphery of the pixel central portion as viewed in the thickness direction of the light receiving layer and has a higher refractive index than the pixel central portion.

  The imaging device according to the third aspect of the present invention includes the solid-state imaging device according to the first aspect or the second aspect.

  The electronic device according to the fourth aspect of the present invention includes the solid-state imaging device according to the first aspect or the second aspect.

  According to the present invention, imaging performance can be improved.

It is a schematic block diagram which shows the solid-state image sensor by 1st Embodiment. It is a figure which shows the circuit structure of the pixel of the solid-state image sensor by 1st Embodiment. It is a sectional side view which shows the solid-state image sensor by 1st Embodiment. It is a sectional side view which shows the structure of the pixel of the solid-state image sensor by 2nd Embodiment. It is a sectional side view which shows the structure of the pixel of the solid-state image sensor by 3rd Embodiment. It is a sectional side view which shows the structure of the pixel of the solid-state image sensor by 4th Embodiment. It is sectional process drawing which shows an example of the manufacturing method of a solid-state image sensor. It is sectional process drawing which shows the other example of the manufacturing method of a solid-state image sensor.

  Next, embodiments will be described with reference to the drawings, but the present invention is not limited to the following embodiments.

[First Embodiment]
FIG. 1 is a schematic configuration diagram illustrating the solid-state imaging device according to the present embodiment. The solid-state image pickup device 1 is a so-called CMOS type solid-state image pickup device, but may be another solid-state image pickup device such as another amplification type or CCD type.

  The solid-state imaging device 1 includes a plurality of pixels 3 two-dimensionally arranged in the pixel region 2 and a peripheral circuit 4 for reading out charges (electric signals) from the pixels 3. The peripheral circuit 4 of the solid-state imaging device 1 includes a vertical scanning circuit 5, a horizontal scanning circuit 6, a readout circuit 7 including a well-known CDS circuit, and an output amplifier 8, similarly to a general CMOS solid-state imaging device. .

  In the solid-state imaging device 1, each of the plurality of pixels 3 outputs an electrical signal corresponding to the amount of incident light. The vertical scanning circuit 5 takes out an electric signal from the pixel 3 (photodiode 15 shown in FIG. 2) to the reading circuit 7 in units of rows. The horizontal scanning circuit 6 supplies the electric signal extracted by the reading circuit 7 to the output amplifier 8 in units of columns. The output amplifier 8 outputs the electrical signal from the readout circuit 7 as an image signal via the output terminal 9.

  The peripheral circuit 4 as described above is disposed, for example, in the peripheral region 10 around the pixel region 2. The peripheral region 10 may be disposed only on the two adjacent sides (for example, the upper side and the left side) of the pixel region 2, or may be disposed on the upper, lower, left, and right sides of the pixel region 2 as the center. The configuration of the peripheral circuit 4 shown in FIG. 1 is an example and can be changed as appropriate.

  FIG. 2 is a diagram illustrating a circuit configuration of the pixel 3 of the solid-state imaging device 1. As shown in FIG. 2, the pixel 3 includes a selection transistor 11, a source follower amplification transistor 12, a reset transistor 13, a transfer transistor 14, and a photodiode 15 as a photoelectric conversion unit. In addition, the code | symbol Vcc of FIG. 2 shows a power supply.

  As shown in FIGS. 1 and 2, the gate of the selection transistor 11 of the pixel 3 is commonly connected to the selection line 20 for each row. The gate of the reset transistor 13 of the pixel 3 is commonly connected to the reset line 21 for each row. The gate of the transfer transistor 14 of the pixel 3 is commonly connected to the transfer line 22 for each row. The sources of the selection transistors 11 of the pixels 3 are commonly connected to the vertical signal line 23 for each column. The selection line 20, the reset line 21 and the transfer line 22 are connected to the vertical scanning circuit 5. The vertical signal line 23 is connected to the readout circuit 7. Note that the circuit configuration of the pixel 3 illustrated in FIG. 2 is an example, and can be changed as appropriate.

  FIG. 3 is a side sectional view showing the structure of the pixel 3 of the solid-state imaging device 1 according to the present embodiment. The solid-state image sensor 1 of the present embodiment is a so-called surface irradiation type solid-state image sensor. The solid-state imaging device 1 has a structure in which an optical layer 33, a wiring layer 34, an intermediate layer 35, and a lens layer 36 are laminated in this order on a light receiving layer 32 formed on a surface layer of a substrate 31.

  In the present embodiment, at least a part of incident light that has entered the lens layer 36 from the outside of the solid-state imaging device 1 passes through the lens layer 36, the intermediate layer 35, the wiring layer 34, and the optical layer 33 and enters the light receiving layer 32. Incident. In the following description, the side on which light is incident on the light receiving layer 32 is appropriately referred to as “upper” or “above”.

  The light receiving layer 32 includes a photodiode 15 (light conversion unit) formed on the surface layer of the substrate 31. The substrate 31 is a semiconductor substrate such as a silicon substrate. The photodiode 15 is provided in each of the plurality of pixels 3. The photodiode 15 generates a charge (power) corresponding to the amount of incident light.

  The optical layer 33 includes an antireflection film 40 provided so as to cover the light incident side of the photodiode 15, a waveguide formation portion 41 disposed around the photodiode 15 when viewed from the thickness direction of the light receiving layer 32, and And an interlayer insulating film 42 provided so as to cover the antireflection film 40 and the waveguide forming portion 41. In the present embodiment, the thickness direction of the light receiving layer 32 (solid-state imaging device 1) may be simply referred to as the thickness direction.

The antireflection film 40 has a film configuration (number of layers, material of each layer, thickness of each layer, and the like) according to the wavelength of incident light. For example, the antireflection film 40 can be configured by a three-layer film including a SiO ₂ layer, a SiN layer (silicon nitride layer), and a SiO ₂ layer that are sequentially stacked from the substrate 31 side. Alternatively, for example, the antireflection film 40 can be formed of a five-layer film including a SiO ₂ layer, a SiN layer, a SiO ₂ layer, a SiN layer, and a SiO ₂ layer that are sequentially stacked from the substrate 31 side.

The waveguide forming portion 41 is provided so that light traveling toward the periphery of the photodiode 15 when viewed from the thickness direction is reflected by the waveguide forming portion 41 so that the light passing through the wiring layer 34 is guided to the photodiode 15. Yes. For example, the waveguide forming portion 41 is formed so as to surround the photodiode 15 in an annular shape when viewed from the thickness direction. The ring shape may be a frame shape or an annular shape. The waveguide forming portion 41 is formed of a material having a refractive index higher than that of the interlayer insulating film 42, for example. The interlayer insulating film 42 is composed of, for example, a SiO ₂ layer.

  The wiring layer 34 is stacked on the optical layer 33. The wiring layer 34 has a so-called multilayer wiring structure, and includes wirings 43 to 45 and interlayer insulating films 46 to 48. The wiring 43 is formed on the interlayer insulating film 42 of the optical layer 33. The interlayer insulating film 46 is formed so as to cover the wiring 43. The wiring 44 is formed on the interlayer insulating film 46. The interlayer insulating film 47 is formed so as to cover the wiring 44. The wiring 45 is formed on the interlayer insulating film 47. The interlayer insulating film 48 is formed so as to cover the wiring 45.

  The wirings 43 to 45 electrically connect the peripheral circuit 4 shown in FIG. 1 and the transistor of each pixel shown in FIG. The wirings 43 to 45 include at least one of the selection line 20, the reset line 21, the transfer line 22, and the vertical signal line 23 illustrated in FIG. For example, in the wiring layer 34, the selection line 20, the transfer line 22, and the vertical signal line 23 are formed in different layers, and the reset line 21 is formed in the same layer as the selection line 20 or the transfer line 22.

  The wiring 45 arranged in the uppermost layer among the wirings 43 to 45 provided in the wiring layer 34 is provided so as to be a light shielding film with respect to the lower layer than the wiring 45. For example, the wiring 45 functions as a light shielding film by being formed of a light reflective conductive material such as aluminum. The various transistors shown in FIG. 2 are arranged so as to be covered with the wiring 45 when viewed from the thickness direction (light incident side). As described above, in the various transistors illustrated in FIG. 2, the occurrence of malfunction due to light is suppressed.

  In addition, wirings other than the wiring 45 among the wirings 43 to 45 provided in the wiring layer 34 may be formed as the light shielding film as described above. Further, two or more of the wirings 43 to 45 provided in the wiring layer 34 may be formed as the light shielding film as described above. Further, the light shielding film as described above may be provided separately from the wirings 43 to 45, and the forming material may be a conductive material or an insulating material.

  The lens layer 36 is laminated on the intermediate layer 35. The lens layer 36 includes microlenses 49 provided in each of the plurality of pixels 3. That is, the microlens 49 is provided in a one-to-one correspondence with the photodiode 15. The microlens 49 condenses the light incident on the microlens 49 from the outside of the solid-state imaging device 1 on the photodiode 15.

  By the way, in a general solid-state imaging device, a part of light (wide-angle component) collected by the microlens may not reach the photodiode due to vignetting in the wiring of the wiring layer. As a result, it may be difficult to capture a bright image. In addition, such wide-angle component light may enter a photodiode of an adjacent pixel. As a result, brightness and color reproducibility may deteriorate (unevenness occurs). Such a decrease in imaging performance may become more prominent as a lens having a higher numerical aperture (NA) is used as a microlens.

  In the present embodiment, the intermediate layer 35 suppresses the occurrence of vignetting in the wiring layer 34 of light passing through the microlens 49. The intermediate layer 35 includes a pixel central portion 50 that includes the center of the pixel 3 when viewed from the thickness direction, and a pixel peripheral portion 51 that is disposed at least partially around the pixel central portion 50 when viewed from the thickness direction.

  In the present embodiment, light incident on the microlens 49 from the outside of the solid-state imaging device 1 passes through the pixel center portion 50 and enters the photodiode 15. Further, at least a part (for example, a wide-angle component) of the light condensed by the microlens 49 is reflected at the interface of the pixel peripheral portion 51 and guided so as to pass through the pixel central portion 50. Therefore, the solid-state imaging device 1 can reduce the loss of light quantity due to vignetting and can capture a bright image. Moreover, since the solid-state image sensor 1 can suppress that a part of light which passed the micro lens 49 of a certain pixel 3 enters into the photodiode 15 of the adjacent pixel 3, it can suppress generation | occurrence | production of a nonuniformity.

  Next, the configuration of the intermediate layer 35 will be described in detail. In the pixel central portion 50, an optical film 52, a passivation film (protective film) 53, an optical film 54, a planarizing film 55, a color filter 56, and a planarizing film 57 are laminated in this order from the lower layer side to the upper layer side. It is a structured.

For example, the refractive index of the optical film 52 is set lower than the refractive index of the passivation film 53 and higher than the refractive index of the interlayer insulating film 42. The interlayer insulating film 35 is composed of, for example, a SiO ₂ film having a refractive index of 1.46. The passivation film 53 is composed of, for example, a SiN film (silicon nitride film) having a refractive index of 2.0. For example, the refractive index of the optical film 54 is set lower than the refractive index of the passivation film 53 and higher than the refractive index of the planarizing film 55. The planarizing film 55 and the planarizing film 57 are formed of, for example, an organic material and a resin film having a refractive index of 1.55. The color filter 56 includes, for example, a red part, a green part, and a blue part arranged for each pixel 3 according to the Bayer array.

As described above, in the present embodiment, the pixel central portion 50 has a multilayer structure in which a plurality of films and color filters are stacked. However, at least one layer thereof may be omitted or a single layer structure may be used. For example, one or both of the optical film 52 and the optical film 54 may be omitted, and one or both of the planarization film 55 and the planarization film 57 may be omitted. In addition, the material for forming each layer of the pixel central portion 50 can be changed as appropriate. For example, the passivation film 53 may be composed of a SiO ₂ film or a SiON film.

  For example, the pixel peripheral portion 51 is arranged so as to surround the pixel central portion 50 in a frame shape (annular shape) when viewed from the thickness direction. The pixel peripheral portion 51 is provided so as to overlap with the center position 58 of the gap between a pair of adjacent microlenses 49 when viewed from the thickness direction. In the present embodiment, the pixel peripheral portion 51 is provided symmetrically with respect to the center position 58 (a surface extending perpendicular to the paper surface of FIG. 3). For example, the pixel peripheral portion 51 is provided so as to be accommodated in a formation region of the wirings 43 to 45 when viewed in the thickness direction.

  The pixel peripheral portion 51 is provided in at least part of the thickness direction of the intermediate layer 35. For example, the pixel peripheral portion 51 is provided on the same level as at least one layer constituting the pixel central portion 50. In the present embodiment, the pixel peripheral portion 51 is provided across all layers of the pixel central portion 50. The pixel peripheral portion 51 is disposed, for example, inside a trench formed in the pixel central portion 50.

  The pixel peripheral portion 51 is set to have a higher refractive index than at least one layer arranged in the same layer as the pixel peripheral portion 51 in the pixel central portion 50. For example, the pixel peripheral portion 51 is set to have a higher refractive index than the color filter 56. In this case, in the first pixel 3, the light passing through the color filter 56 toward the adjacent second pixel 3 is reflected by the interface of the pixel peripheral portion 51, thereby causing the pixel central portion of the first pixel 3 to be reflected. It is returned to the 50 side. Thereby, the occurrence of vignetting in the wiring layer 34 is suppressed.

  The pixel peripheral portion 51 may have a refractive index higher than that of the planarization film (one or both of the planarization film 55 and the planarization film 57). In this case, the light that passes through the planarization film and travels toward the adjacent pixel 3 is returned to the pixel central portion 50, so that the occurrence of vignetting in the wiring layer 34 is suppressed. Further, the pixel peripheral portion 51 may have a higher refractive index than one or both of the optical film 52 and the optical film 54, and may have a higher refractive index than the passivation film 53.

  The refractive index of the pixel peripheral portion 51 is set to be higher than the average refractive index of the pixel central portion 50, for example. Here, the refractive index (average refractive index) obtained by weighting the refractive index of each film constituting the pixel central portion 50 by the thickness of each film is 1.5, for example. In this case, for example, the refractive index of the pixel peripheral portion 51 is set to be larger than 1.2 times the average refractive index (1.5) of the pixel central portion 50, that is, larger than 1.8. Further, the refractive index of the pixel peripheral portion 51 is set, for example, 0.3 or more larger than the average refractive index (1.5) of the pixel central portion 50, that is, larger than 1.8.

  The pixel peripheral portion 51 can return light toward the pixel peripheral portion 51 to the pixel central portion 50 side as the refractive index is set higher than the pixel central portion 50 of the same layer, and the refractive index is 2 It may be set larger than 0.0. Moreover, the pixel peripheral part 51 can reduce the light loss in the pixel peripheral part 51 by setting the extinction coefficient k to 0 or less (k <= 0).

  By the way, the layer having a relatively thick thickness in the pixel central portion 50 tends to increase the amount of light directed to the side in the thickness direction as compared with the layer having a relatively thin thickness in the pixel central portion 50. For this reason, the solid-state imaging device 1 improves the imaging performance when the pixel peripheral portion 51 is configured to return the light directed to the pixel peripheral portion 51 side through the relatively thick layer to the pixel central portion 50 side. High effect. Examples of the relatively thick layer in the pixel central portion 50 include a color filter 56, a planarizing film 55, and a planarizing film 57. A relatively thick layer in the pixel central portion 50 is a layer formed of an organic material, for example. The pixel peripheral portion 51 may be provided in the same layer as at least one of the layers having a relatively thick thickness in the pixel central portion 50.

  Further, as a relatively thin layer in the pixel central portion 50, for example, a passivation film 53 can be cited. The relatively thin layer in the pixel central portion 50 is a layer formed of an inorganic material, for example. The pixel peripheral portion 51 may have a refractive index lower than that of at least one of the relatively thin layers in the pixel central portion 50. Further, the pixel peripheral portion 51 may not be provided in the same layer as at least one of the layers having a relatively thin thickness in the pixel central portion 50.

  The formation material of the pixel peripheral portion 51 is appropriately selected so as to have the refractive index as described above. For example, the pixel peripheral portion 51 may be formed of an inorganic material such as SiN, or may be formed of a resin material. The refractive index of the pixel peripheral portion 51 can be adjusted, for example, by adding fine particles (filler) to the forming material (for example, resin material).

  In the solid-state imaging device 1 of the present embodiment as described above, the intermediate layer 35 disposed between the lens layer 36 and the wiring layer 34 has a pixel periphery disposed around the pixel center portion 50 as viewed from the thickness direction. Including the part 51, the refractive index of the pixel peripheral part 51 is higher than that of the pixel central part 50. Therefore, the solid-state imaging device 1 can collect the light that faces the outside of the pixel 3 when viewed from the thickness direction in the pixel central portion 50. As a result, the solid-state imaging device 1 can suppress the occurrence of vignetting in the wiring 45 and can capture a bright image. Further, in the solid-state imaging device 1, light passing through the microlens 49 of a certain pixel 3 is suppressed from entering the photodiode 15 of the adjacent pixel 3, and occurrence of unevenness due to crosstalk or the like is suppressed. Thus, according to the present embodiment, the imaging performance can be improved.

  In the present embodiment, the pixel peripheral portion 51 is provided symmetrically with respect to the center position 58 between the pair of adjacent microlenses 49. Therefore, in the solid-state imaging device 1, the relationship between the amount of light passing through the microlens 49 and the output is uniform in the plurality of pixels 3, and the occurrence of unevenness can be suppressed. Further, in the present embodiment, since the pixel peripheral portion 51 is provided so as to be accommodated in the formation region of the wiring 45 when viewed from the thickness direction, the light loss at the pixel peripheral portion 51 can be reduced.

  In the present embodiment, the solid-state imaging device 1 has a waveguide forming portion 41 that guides light that has passed through the intermediate layer 35 to the photodiode 15. Therefore, the solid-state imaging device 1 can capture a bright image with reduced light loss between the intermediate layer 35 and the photodiode 15.

[Second Embodiment]
Next, a second embodiment will be described. In the present embodiment, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

  FIG. 4 is a schematic configuration diagram illustrating the solid-state imaging device 1 according to the present embodiment. The pixel peripheral portion 51 is provided so as to surround the center of the photodiode 15 in a frame shape when viewed from the thickness direction. In the present embodiment, the outer dimension (outer shape) of the region (pixel central portion 50) surrounded by the pixel peripheral edge 51 is referred to as the inner dimension (inner diameter) of the pixel peripheral edge 51.

  In the present embodiment, when viewed from the thickness direction, the pixel peripheral portion 51 has an inner diameter R1 closer to the light receiving layer 32 (lower side) than an inner diameter R2 closer to the lens layer 36 (upper side). The pixel peripheral portion 51 includes a tapered shape in which the inner diameter decreases from the side closer to the light receiving layer 32 toward the side closer to the lens layer 36. In this tapered shape, the angle (taper angle α) between the bottom surface 51a and the side surface 51b of the pixel peripheral edge 51 is set to 70 ° or more, for example. Here, the bottom surface 51 a of the pixel peripheral portion 51 protrudes from the wiring 45 of the wiring layer 34 toward the center side of the photodiode 15 (pixel 3). In the example shown in FIG. 4, the pixel peripheral portion 51 has a sharp shape at the end on the lens layer 36 side, but the end may have a rounded shape.

  In the present embodiment, incident light incident on the microlens 49 from the outside of the solid-state imaging device 1 is reflected by the side surface 51b of the pixel peripheral portion 51 and is folded back toward the pixel central portion 50 side. If the taper-shaped taper angle α of the pixel peripheral portion 51 is 70 ° or more, for example, light reflected toward the outside of the solid-state imaging device 1 is reduced, and light loss is reduced. This incident light is incident on the wiring layer 34 through the opening of the bottom surface 51a of the pixel peripheral portion 51 while the spot diameter is reduced. Since the bottom surface 51a projects to the center side of the pixel 3 from the wiring 45, the incident light passing through the opening of the bottom surface 51a is suppressed from being scattered by the wiring 45.

  As described above, the solid-state imaging device 1 according to the present embodiment can collect light that is directed to the outside of the pixel 3 when viewed from the thickness direction in the pixel central portion 50, capture a bright image, and suppress occurrence of unevenness. You can do it.

  The pixel peripheral portion 51 of the present embodiment can be obtained, for example, by forming a film on the wiring layer 34 and then forming a hole in the pixel central portion 50 in the film. When the pixel peripheral portion 51 is formed by such a method, the pixel peripheral portion 51 is easily formed because the side surface 51b is inclined with respect to the bottom surface 51a. For example, when the thickness of the pixel peripheral portion 51 is increased as compared with the configuration in which the side surface 51b is perpendicular to the bottom surface 51a, it is easy to form a hole in which the pixel central portion 50 is disposed. Therefore, for example, it becomes easy to form the pixel peripheral portion 51 corresponding to a relatively thick layer in the pixel central portion 50.

  In the present embodiment, the solid-state imaging device 1 does not include the waveguide forming portion 41. As described above, in the solid-state imaging device 1, the waveguide forming portion 41 may be omitted, or the antireflection film 40 may be omitted.

[Third Embodiment]
Next, a third embodiment will be described. In the present embodiment, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

  FIG. 5 is a schematic configuration diagram illustrating the solid-state imaging device 1 according to the present embodiment. In the present embodiment, the pixel peripheral portion 51 has a lower layer portion 60 formed on the wiring layer 34 and an upper layer portion 61 provided closer to the lens layer 36 than the lower layer portion 60. The lower layer portion 60 and the upper layer portion 61 each have a lattice shape when viewed from the thickness direction, and are provided so as to surround the pixel central portion 50 in a frame shape.

  In the pixel peripheral portion 51, the inner diameter R <b> 1 on the side closer to the light receiving layer 32 (lower layer portion 60) is smaller than the inner diameter R <b> 2 on the side closer to the lens layer 36 (upper layer portion 61). The pixel peripheral portion 51 has a step between the inner peripheral surface of the lower layer portion 60 and the inner peripheral surface of the upper layer portion 61. That is, the inner diameter R2 of the upper layer portion 61 changes stepwise from the inner diameter R1 of the lower layer portion 60, and is discontinuous with the inner diameter R1 of the lower layer portion 60.

  In the example shown in FIG. 5, the lower layer portion 60 is provided on the same level as the optical film 52, the passivation film 53, and the optical film 54. The upper layer portion 61 is provided on the same level as the planarizing film 55 and the color filter 56. The planarization film 57 is provided so as to planarize the color filter 56 and the upper layer portion 61 of the pixel peripheral portion 51.

  One or both of the upper layer portion 61 and the lower layer portion 60 is set to have a higher refractive index than at least one of the layers of the pixel central portion 50 arranged in the same layer. In the present embodiment, the upper layer portion 61 is set to have a higher refractive index than at least one of the layers arranged in the same layer as the upper layer portion 61 in the pixel central portion 50. In the present embodiment, the lower layer portion 60 is set to have a higher refractive index than at least one of the layers arranged in the same hierarchy as the lower layer portion 60 in the pixel central portion 50. The refractive index of the upper layer portion 61 may be the same as or different from the refractive index of the lower layer portion 60. Further, the formation material of the upper layer portion 61 may be the same as or different from the formation material of the lower layer portion 60.

  As described in the above embodiment, the solid-state imaging device 1 according to the present embodiment can collect the light toward the outside of the pixel 3 when viewed from the thickness direction in the pixel central portion 50 and capture a bright image. The occurrence of unevenness can be suppressed. Moreover, since the solid-state image sensor 1 of this embodiment can form separately the upper layer part 61 and the lower layer part 60, the freedom degree of a formation process and the freedom degree of material selection are high.

[Fourth Embodiment]
Next, a fourth embodiment will be described. In the present embodiment, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

  FIG. 6 is a schematic configuration diagram illustrating the solid-state imaging device 1 according to the present embodiment. In the present embodiment, the solid-state imaging device 1 is a so-called back-illuminated solid-state imaging device. The solid-state imaging device 1 illustrated in FIG. 6 includes the light receiving layer 32, the lens layer 36, and the intermediate layer 35 as described in the above embodiment. In the present embodiment, the wiring layer 34 is provided opposite to the lens layer 36 with respect to the light receiving layer 32.

  In the present embodiment, the pixel center portion 50 of the intermediate layer 35 includes a color filter 56 stacked on the optical layer 33 and a planarizing film 57 stacked on the color filter 56. The pixel peripheral portion 51 of the intermediate layer 35 is formed over the same layer as the color filter 56 and the same layer as the planarization film 57.

  As described in the above embodiment, the solid-state imaging device 1 according to the present embodiment can collect the light toward the outside of the pixel 3 when viewed from the thickness direction in the pixel central portion 50 and capture a bright image. The occurrence of unevenness can be suppressed.

  The solid-state imaging device 1 of each embodiment as described above can be used for an imaging device such as a camera, for example. The imaging device includes, for example, a solid-state imaging device 1 and a photographing lens. Since this imaging device has high imaging performance of the solid-state imaging device 1, it can capture a high-quality image. The solid-state image sensor 1 can also be used for electronic devices such as a portable terminal with a photographing function.

  The solid-state imaging device 1 can be used as a light detection unit that detects light in an electronic device such as a measurement device that performs optical measurement or an electronic device that includes such a measurement device. Examples of the measurement device that performs optical measurement include a shape measurement device that measures a shape, a distance measurement device that measures a distance such as a laser interferometer and a focusing device, and a position measurement device such as an encoder. As an electronic apparatus provided with such a measuring apparatus, for example, an exposure apparatus or the like can be cited.

  Next, an example of a method for manufacturing the solid-state imaging device 1 according to the above-described embodiment will be described. FIG. 7 is a cross-sectional process diagram illustrating an example of a method for manufacturing a solid-state imaging device. In FIG. 7, illustration of the structure below the wiring layer 34 is omitted.

  In this example, in order to manufacture the solid-state imaging device 1, the light receiving layer 32 is formed on the substrate 31 shown in FIG. 3 and the like, the optical layer 33 is formed on the light receiving layer 32, and then the wiring is formed on the optical layer 33. Layer 34 is formed. Next, as illustrated in FIG. 7A, the films constituting the pixel central portion 50 of the intermediate layer 35 are stacked, and a stacked body that will later become the pixel central portion 50 is formed. Next, as shown in FIG. 7B, by patterning the stacked body, a trench T is formed in a region of the stacked body where the pixel peripheral portion 51 is disposed. Next, as illustrated in FIG. 7C, the pixel peripheral edge 51 is formed inside the trench T. Next, for example, the lens layer 36 illustrated in FIG. 3 is formed over the planarization film 57 and the pixel peripheral portion 51, and the solid-state imaging device 1 is obtained. The formation of each part as described above can be performed by appropriately using a known film forming technique, resist technique, photolithography method, and etching technique.

  Next, another example of the method for manufacturing the solid-state imaging device 1 will be described with reference to FIG. FIG. 8 is a cross-sectional process diagram illustrating another example of the method for manufacturing the solid-state imaging device 1. In FIG. 8, illustration of the structure below the wiring layer 34 is omitted.

  In this example, the pixel peripheral portion 51 is formed only in the same layer as the color filter 56 in the intermediate layer 35. In this example, in order to manufacture the solid-state imaging device 1, the light receiving layer 32 is formed on the substrate 31 shown in FIG. 3 and the like, the optical layer 33 is formed on the light receiving layer 32, and then the wiring is formed on the optical layer 33. Layer 34 is formed. Next, as shown in FIG. 8A, an optical film 52, a passivation film 53, an optical film 54, and a planarizing film 55 are stacked in this order on the wiring layer. Next, as illustrated in FIG. 8B, a film 51 c that will later become the pixel central portion 50 is formed over the planarization film 55. Next, as shown in FIG. 8C, by patterning the film 51c, a hole is formed in a region of the film 51c where the color filter 56 (pixel central portion 50) is disposed. In this way, the film 51c becomes the partition-like pixel peripheral portion 51 having a hole. Next, as illustrated in FIG. 8D, the color filter 56 is formed inside the hole of the pixel peripheral portion 51. Next, for example, the flattening film 57 shown in FIG. 3 is formed over the color filter 56 and the pixel peripheral portion 51, and the lens layer 36 is formed on the flattening film 57. Is obtained.

DESCRIPTION OF SYMBOLS 1 ... Solid-state image sensor, 3 ... Pixel, 32 ... Light receiving layer, 34 ... Wiring layer, 35 ... Intermediate | middle layer, 36 ... Lens layer, 40 ... Antireflection film, 43-45 ... wiring, 50 ... pixel center, 51 ... pixel peripheral edge, 58 ... center position, 60 ... lower layer, 61 ... upper layer, R1 ... inner diameter , R2 ... Inner diameter, T ... Trench

Claims (17)

A light receiving layer including a photoelectric conversion unit disposed in each of the two-dimensionally arranged pixels;
A lens layer including a lens element for condensing light on the photoelectric conversion unit;
A wiring layer disposed between the lens layer and the light receiving layer and including a wiring electrically connected to a circuit for reading out electric charges from the photoelectric conversion unit;
An intermediate layer disposed between the wiring layer and the lens layer,
The intermediate layer is
A pixel central portion overlapping with the center of the photoelectric conversion portion as seen from the thickness direction of the light receiving layer;
A solid-state imaging device including a pixel peripheral portion disposed at least at a part of the periphery of the pixel central portion as viewed from the thickness direction of the light receiving layer and having a refractive index higher than that of the pixel central portion. A back-illuminated solid-state imaging device,
A light receiving layer including a photoelectric conversion unit disposed in each of the two-dimensionally arranged pixels;
A lens layer including a lens element for condensing light on the photoelectric conversion unit;
An intermediate layer disposed between the light receiving layer and the lens layer,
The intermediate layer is
A pixel central portion overlapping with the center of the photoelectric conversion portion as seen from the thickness direction of the light receiving layer;
A solid-state imaging device including a pixel peripheral portion disposed at least at a part of the periphery of the pixel central portion as viewed from the thickness direction of the light receiving layer and having a refractive index higher than that of the pixel central portion. The solid-state imaging device according to claim 1, wherein a refractive index of a pixel peripheral portion of the intermediate layer is 1.2 times or more a refractive index of the pixel central portion. 4. The solid-state imaging device according to claim 1, wherein a refractive index of a pixel peripheral portion of the intermediate layer is 0.3 or more larger than a refractive index of the pixel central portion. The solid-state imaging device according to claim 1, wherein a refractive index of a pixel peripheral portion of the intermediate layer is greater than 1.8. 6. The solid-state imaging device according to claim 1, wherein the pixel peripheral portion of the intermediate layer has a refractive index larger than 2.0 and an extinction coefficient of 0 or less. The lens element is arranged in a one-to-one correspondence with the photoelectric conversion unit,
7. The solid-state imaging device according to claim 1, wherein the pixel peripheral portion of the intermediate layer is provided symmetrically with respect to a center position between a pair of adjacent lens elements. The solid-state imaging device according to claim 1, wherein a pixel peripheral portion of the intermediate layer is provided so as to be accommodated in a formation region of the wiring as viewed from a thickness direction of the light receiving layer. 9. The solid according to claim 1, further comprising: a waveguide that is disposed between a wiring closest to the intermediate layer among the wirings of the wiring layer and the light receiving layer and guides light from the intermediate layer to the photoelectric conversion unit. Image sensor. The solid-state imaging device according to claim 1, wherein the intermediate layer includes a color filter. The solid-state imaging device according to claim 10, wherein the pixel peripheral portion is provided in at least the same layer as the color filter in the intermediate layer. The pixel peripheral portion of the intermediate layer surrounds the photoelectric conversion portion in an annular shape when viewed from the thickness direction of the light receiving layer, and the inner diameter on the light receiving layer side is smaller than the inner diameter on the lens layer side. The solid-state image sensor as described in any one of Claims. The solid-state imaging according to claim 12, wherein a pixel peripheral edge portion of the intermediate layer includes a tapered shape having an inner diameter that decreases from the light receiving layer side toward the lens layer side, and a taper angle of the tapered shape is 70 ° or more. element. The pixel periphery of the intermediate layer is
The lower layer,
The solid-state imaging device according to claim 12, further comprising: an upper layer portion that is provided closer to the lens layer than the lower layer portion and has a discontinuous inner diameter. The solid-state imaging device according to claim 1, wherein a pixel peripheral edge portion of the intermediate layer is disposed inside a trench formed in the intermediate layer.   The imaging device provided with the solid-state image sensor as described in any one of Claims 1-15.   The electronic device provided with the solid-state image sensor as described in any one of Claims 1-15.

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