JP2013125933A - Solid-state imaging device and camera module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid-state imaging device capable of preventing color mixture.SOLUTION: A solid-state imaging device 12 includes a semiconductor substrate 17, a plurality of color filter layers, a shield layer 21, and a plurality of micro lenses 16. The semiconductor substrate 17 has a plurality of photodiodes 18. The plurality of color filter layers are composed of G filter layers 20G, B filter layers 20B, and R filter layers 20R, and they are formed so as to be spaced apart from one another on the semiconductor substrate 17. The shield layer 21 is composed of a material having a lower refractive index than the color filter layers and is provided between the plurality of color filter layers. The plurality of micro lenses 16 is formed on the plurality of color filter layers including the shield layer 21.

Description

  Embodiments described herein relate generally to a solid-state imaging device and a camera module.

  In the conventional solid-state imaging device, pixels including photodiodes and any one of R, G, and B color filter layers are arranged in a grid pattern.

  In recent years, solid-state imaging devices have been miniaturized and reduced in height. When a conventional solid-state imaging device that is miniaturized and reduced in height is applied to a camera module, light is incident on the pixels in the peripheral portion from an extremely inclined direction. When light is incident in this way, the incident light is condensed on photodiodes of other pixels, and color mixing occurs in the captured image. Therefore, color mixing also occurs in the output image from the camera module to which the solid-state imaging device is applied.

JP 2011-119445 A JP 2009-88415 A

  An object of the embodiments is to provide a solid-state imaging device and a camera module capable of suppressing color mixing.

  The solid-state imaging device according to the embodiment includes a semiconductor substrate, a plurality of color filter layers, a shielding layer, and a plurality of microlenses. The semiconductor substrate has a plurality of photodiodes. The plurality of color filter layers are formed on the semiconductor substrate so as to be separated from each other. The shielding layer is made of a material having a lower refractive index than the color filter layer, and is formed between the plurality of color filter layers. The plurality of microlenses are formed on the plurality of color filter layers including the shielding layer.

  The camera module according to the embodiment includes a solid-state imaging device and a lens holder. The solid-state imaging device includes a semiconductor substrate, a plurality of color filter layers, a shielding layer, and a plurality of microlenses. The semiconductor substrate has a plurality of photodiodes. The plurality of color filter layers are formed on the semiconductor substrate so as to be separated from each other. The shielding layer is made of a material having a lower refractive index than the color filter layer, and is formed between the plurality of color filter layers. The plurality of microlenses are formed on the plurality of color filter layers including the shielding layer. The lens holder is cylindrical and is disposed so as to cover the solid-state imaging device, and has a lens for condensing light on the solid-state imaging device.

It is a longitudinal cross-sectional view which shows the camera module which concerns on 1st Embodiment. It is a longitudinal cross-sectional view which shows the principal part of the solid-state imaging device which concerns on 1st Embodiment. It is sectional drawing of the solid-state imaging device along the dotted line XX 'of FIG. It is a figure for demonstrating the manufacturing method of the solid-state imaging device which concerns on 1st Embodiment, Comprising: It is sectional drawing which shows the process of forming a 1st planarization layer. It is a figure for demonstrating the manufacturing method of the solid-state imaging device which concerns on 1st Embodiment, Comprising: It is sectional drawing which shows the process of forming G filter layer. It is a figure for demonstrating the manufacturing method of the solid-state imaging device which concerns on 1st Embodiment, Comprising: It is sectional drawing which shows the process of forming a shielding layer. Similarly, it is a view for explaining the method for manufacturing the solid-state imaging device according to the first embodiment, and is a cross-sectional view showing a step of forming a shielding layer. It is a figure for demonstrating the manufacturing method of the solid-state imaging device which concerns on 1st Embodiment, Comprising: It is sectional drawing which shows the process of forming B filter layer. It is a figure for demonstrating the manufacturing method of the solid-state imaging device which concerns on 1st Embodiment, Comprising: It is sectional drawing which shows the process of forming a 2nd planarization layer. It is a figure for demonstrating the modification of the manufacturing method of the solid-state imaging device which concerns on 1st Embodiment, Comprising: It is sectional drawing which shows the process of forming G filter layer and B filter layer. It is a figure for demonstrating the modification of the manufacturing method of the solid-state imaging device which concerns on 1st Embodiment, Comprising: It is sectional drawing which shows the process of forming a groove | channel between a G filter layer and a B filter layer. It is a figure for demonstrating a mode that the light which injected into the solid-state imaging device which concerns on 1st Embodiment advances. It is a longitudinal cross-sectional view which shows the solid-state imaging device which concerns on 2nd Embodiment. It is a figure for demonstrating the manufacturing method of the solid-state imaging device which concerns on 2nd Embodiment, Comprising: It is sectional drawing which shows the process of forming a shielding layer.

  The solid-state imaging device and camera module according to the embodiment will be described below.

(First embodiment)
FIG. 1 is a longitudinal sectional view showing a camera module 10 according to the present embodiment. A camera module 10 shown in FIG. 1 includes a solid-state imaging device 12 placed on a circuit board 11 and a lens holder 13 fixed to a side surface of the circuit board 11 so as to cover the circuit board 11 including the solid-state imaging device 12. And having.

  The lens holder 13 has a cylindrical shape having a top plate at one end, and has a lens 14 and an infrared blocking filter 15. The lens 14 is disposed in an opening provided on the top plate of the lens holder 13, and condenses light incident on the camera module 10 on the solid-state imaging device 12. The infrared blocking filter 15 is disposed inside the lens holder 13 and suppresses the infrared component of the light incident on the camera module 10 from reaching the solid-state imaging device 12.

  The solid-state imaging device 12 has a plurality of convex microlenses 16. The plurality of microlenses 16 are two-dimensionally arranged in a grid. Each microlens 16 is in contact with another microlens 16 adjacent in the vertical and horizontal directions.

  FIG. 2 is a vertical cross-sectional view showing the main part of the solid-state imaging device 12. The solid-state imaging device 12 shown in FIG. 2 is a so-called back-illuminated solid-state imaging device.

  In the solid-state imaging device 12, a plurality of photodiodes 18 are formed on a P-type semiconductor substrate 17 made of, for example, silicon. The plurality of photodiodes 18 are arranged in a lattice shape according to the arrangement of the plurality of microlenses 16.

  A transparent first planarizing layer 19 is formed on the surface of the semiconductor substrate 17 including the photodiode 18. The surface of the first planarization layer 19 is planarized by, for example, a CMP method.

  A plurality of filter layers are formed on the surface of the first planarization layer 19. The plurality of filter layers are color filter layers having different transmission wavelength ranges, for example. In the present embodiment, the plurality of filter layers include a red color filter layer (hereinafter referred to as R filter layer) (not shown) that transmits red component light, and a green color filter layer 20G (hereinafter referred to as R filter layer) that transmits green component light. G filter layer 20G) and a blue color filter layer 20B that transmits blue component light (hereinafter referred to as B filter 20B layer). The R filter layer, the G filter layer 20G, and the B filter layer 20B are arranged in a lattice pattern according to the arrangement of the plurality of photodiodes 18, and are separated from each other.

  A shielding layer 21 is formed between the R filter layer, the G filter layer 20G, and the B filter layer 20B. The shielding layer 21 is made of, for example, a resist material having a lower refractive index than the R filter layer, the G filter layer 20G, and the B filter layer 20B. In general, the refractive index of the R filter layer, the G filter layer 20G, and the B filter layer 20B is about 1.6 to 1.7, while the refractive index of the shielding layer 21 is, for example, 1.3 to 1. About 4.

  The refractive index of the shielding layer 21 is preferably lower than the refractive indexes of the R filter layer, the G filter layer 20G, and the B filter layer 20B. However, it is not preferable to form an air layer having a refractive index of about 1.0 as the blocking layer 21, that is, to provide a space between the R filter layer, the G filter layer 20G, and the B filter layer 20B. This is because when a microlens material having a high refractive index enters between the color filter layers in the formation process of the microlens 18 and remains, a high refractive layer is formed between the color filter layers, and functions as the shielding layer 21. This is because of damage.

  FIG. 3 is a cross-sectional view of the solid-state imaging device 12 taken along the dotted line XX ′ in FIG. As shown in FIG. 3, the R filter layer 20R, the G filter 20G, and the B filter 20B are, for example, arranged in a Bayer array, and are arranged at positions separated from each other. The shielding layer 21 is formed so as to fill the space between the R filter layer 20R, the G filter layer 20G, and the B filter layer 20B.

  Refer to FIG. 2 again. A transparent second planarization layer 22 is formed on the R filter layer, the G filter layer 20G, and the B filter layer 20B including the shielding layer 21. The surface of the second planarization layer 22 is planarized by, for example, a CMP method.

  The second planarization layer 22 is made of a material having a higher refractive index than the shielding layer 21. As a result, light incident toward the upper surface of the shielding layer 21 via the microlens 16 is reflected on the upper surface of the shielding layer 21, and thus prevents light from entering the shielding layer 21. Therefore, it is possible to suppress color mixing.

  On the other hand, when the second planarizing layer 22 is formed of a material having a refractive index equal to or lower than that of the shielding layer 21, light incident toward the upper surface of the shielding layer 21 is shielded. It penetrates into the layer 21 and reaches the photodiode 18 without passing through the color filter layer. That is, the light reaches the photodiode 18 without being split into the shielding layer 21. Therefore, color mixing occurs.

  In order to further suppress the occurrence of color mixing, the first planarization layer 19 described above may be formed of a material having a refractive index lower than that of the shielding layer 21. As a result, the light that has entered the shielding layer 21 is reflected by the first planarization layer 19, so that the light that has entered the shielding layer 21 can be prevented from reaching the photodiode 18.

  A plurality of microlenses 16 are formed on the surface of the second planarization layer 22. These microlenses 16 are formed by forming a material such as a transparent resin into a convex lens shape.

  A wiring layer 24 is formed on the back surface of the semiconductor substrate 17 via an oxide film 23. In the wiring layer 24, an interlayer insulating film 24b is formed between the plurality of wirings 24a. By forming the wiring layer 24 on the back surface of the semiconductor substrate 17, the degree of freedom in designing the wiring 24a can be improved, so that the thickness of the wiring layer 24 can be reduced. Accordingly, the back-illuminated solid-state imaging device 12 can be reduced in height as compared with the front-illuminated solid-state imaging device.

  Next, a method for manufacturing the solid-state imaging device 12 shown in FIG. 2 will be described with reference to FIGS. 4 to 11 are cross-sectional views for explaining a method for manufacturing the solid-state imaging device 12.

  As shown in FIG. 4, a plurality of photodiodes 18 are formed, and a first planarizing layer 19 is formed on the surface of the semiconductor substrate 17 having the wiring layer 24 formed on the back surface. The first planarization layer 19 is formed by adopting, for example, a CMP method so that the surface thereof is planarized.

  Next, as shown in FIG. 5, a G filter layer 20 </ b> G is formed at a predetermined position on the surface of the first planarization layer 19. For example, a plurality of G filter layers 20G are formed on the surface of the first planarization layer 19, and the plurality of G filter layers 20G are arranged in a checkered pattern.

  Next, as shown in FIG. 6, a shielding material 21 ′ serving as a shielding layer is formed on the surface of the first planarization layer 19 exposed from between the G filter layers 20G. The shielding material 21 ′ is a material having a lower refractive index than the G filter layer 20G, the B filter layer, and the R filter layer, and is formed so as to fill the gap between the G filter layers 20G.

  Next, as shown in FIG. 7, the shielding layer 21 is formed at a predetermined position on the surface of the first planarization layer 19 by removing a part of the shielding material 21 ′. The shielding layer 21 is formed as follows, for example.

  First, a resist layer 25 is formed on the G filter layer 20G including the shielding material 21 ′, and openings 25a for forming the R filter layer and the B filter layer are formed in the resist layer 25. A part of the shielding material 21 ′ is exposed from the opening 25a.

  Next, a part of the shielding material 21 ′ is etched by RIE or the like using the resist layer 25 having the opening 25 a as a mask. By this etching process, unnecessary portions of the shielding material 21 ′ are removed, and the shielding layer 21 is formed by the shielding material 21 ′ remaining on the side surface of the G filter layer 20G.

  For example, after the resist layer 25 shown in FIG. 7 is removed, as shown in FIG. 8, a B filter layer 20B and an R filter layer (not shown) are filled so as to fill a gap between the G filter layers 20G having the shielding layers 21 on the side surfaces. ).

  Next, as illustrated in FIG. 9, the second planarization layer 22 is formed on the surfaces of the G filter layer 20 </ b> G, the B filter layer 20 </ b> B, the R filter layer, and the shielding layer 21. The second planarization layer 22 is formed using a material having a higher refractive index than that of the shielding layer 21 and adopting a CMP method or the like, for example, so that the surface thereof is planarized.

  Finally, by forming a plurality of microlenses 16 on the second planarization layer 22, the solid-state imaging device 12 shown in FIG. 2 is manufactured.

  In addition to the method described above, the shielding layer 21 may be formed, for example, as shown below. That is, after forming the G filter layer 20G as shown in FIG. 5, the B filter layer 20B and the surface of the first planarization layer 19 exposed from between the G filter layers 20G are formed as shown in FIG. An R filter layer (not shown) is formed. The B filter layer 20B and the R filter layer are formed so as to fill a gap between the G filter layers 20G.

  Next, as shown in FIG. 11, the boundary portion between the G filter layer 20G and the B filter layer 20B and the boundary portion between the G filter layer 20G and the R filter layer are removed, and the G filter layer 20G and the B filter layer 20B are removed. And the groove 26 are formed between the G filter layer 20G and the R filter layer. The groove 26 is formed as follows, for example.

  First, a resist layer 27 is formed on the G filter layer 20G, the B filter layer 20B, and the R filter layer, and an opening 27a for forming the groove 26 is formed in the resist layer 27. From the opening 27a, a boundary portion between the G filter layer 20G and the B filter layer 20B and a boundary portion between the G filter layer 20G and the R filter layer are exposed.

  Next, using the resist layer 27 having the opening 27a as a mask, the boundary portion between the G filter layer 20G and the B filter layer 20B and the boundary portion between the G filter layer 20G and the R filter layer are etched by RIE or the like. . By this etching process, the boundary portion between the G filter layer 20G and the B filter layer 20B and the boundary portion between the G filter layer 20G and the R filter layer are removed, and between the G filter layer 20G and the B filter layer 20B, and G A groove 26 is formed between the filter layer 20G and the R filter layer.

  The shielding layer 21 may be formed so as to fill the groove 26 shown in FIG.

  Next, the manner in which light incident on the solid-state imaging device 12 manufactured in this manner from an extremely oblique direction travels will be described with reference to FIG. FIG. 12 is a diagram for explaining how light L1 and L2 incident on the solid-state imaging device 12 according to the embodiment travels.

  As shown in FIG. 12, a portion L1 of light incident on the solid-state imaging device 12 from an extremely oblique direction is refracted on the surface of the microlens 16, passes through a predetermined color filter layer, and passes through a predetermined photodiode. 18 is condensed. For example, as shown in the drawing, the light passes through the G filter layer 20G and is condensed on the photodiode 18 corresponding to the G filter layer 20G provided immediately below the filter layer 20G.

  On the other hand, another part L2 of the light incident on the solid-state imaging device 12 from an extremely oblique direction is refracted on the surface of the microlens 16, and after passing through a predetermined color filter layer, a predetermined photodiode 18 is present. Does not proceed in the direction of For example, as shown in the drawing, after passing through the G filter layer 20G, the light does not travel in the direction in which the photodiode 18 corresponding to the filter layer 20G exists.

  Here, if the shielding layer 21 is not present, the light after passing through the G filter layer 20G further passes through the adjacent B filter layer 20B and then passes through a predetermined photodiode as indicated by a dotted arrow in the figure. The light is condensed on another photodiode 18 adjacent to 18 (photodiode 18 corresponding to the B filter layer 20B). This is the cause of color mixing.

  However, when the shielding layer 21 is provided as in the solid-state imaging device 12 according to the present embodiment, the light after passing through the G filter layer 20G is reflected by the shielding layer 21 as indicated by a solid arrow in the drawing. Then, the light is condensed on a predetermined photodiode 18 corresponding to the G filter layer 20G.

  In other words, the shielding layer 21 between the G filter layer 20G, the B filter layer 20B, and the R filter layer is within the pixel composed of the color filter layer of any one of the micro lenses 16, R, G, and B, and the photodiode 16. And confine incident light.

  As described above, according to the camera module 10 and the solid-state imaging device 12 according to the present embodiment, the filter layers 20R and 20G are interposed between the R filter layer 20R, the G filter layer 20G, and the B filter layer 20B. The shielding layer 21 is formed of a material having a refractive index lower than 20B. Therefore, even when light is incident from an extremely oblique direction, the light can pass through the predetermined filter layer and be condensed on the photodiode 18 corresponding to the passed filter layer. Therefore, according to the camera module 10 and the solid-state imaging device 12 according to the present embodiment, the occurrence of color mixing can be suppressed.

  In addition, according to the camera module 10 and the solid-state imaging device 12 according to the present embodiment, even if light is incident from an extremely oblique direction, the light can be condensed on a predetermined photodiode 18. Accordingly, light of substantially uniform intensity is collected on each photodiode 18. Therefore, it is possible to suppress the difference in brightness that occurs in the captured image. That is, according to the camera module 10 and the solid-state imaging device 12 according to the present embodiment, shading can be improved.

  Furthermore, according to the camera module 10 according to the present embodiment, even when light is incident on the solid-state imaging device 12 from an extremely oblique direction, the light can be condensed on a predetermined photodiode 18. In addition, it is not necessary to make a multilayer of the lens 14 of the camera module 10 in order to make light incident on the solid-state imaging device 12 from the vertical direction. Therefore, according to the camera module 10 according to the present embodiment, color mixing can be suppressed and shading can be improved without increasing costs.

(Second Embodiment)
FIG. 13 is a longitudinal sectional view showing the solid-state imaging device according to the present embodiment. The camera module according to the second embodiment is the same as the camera module according to the first embodiment except that the structure of the solid-state imaging device is different. Omitted.

  As shown in FIG. 13, in the solid-state imaging device 30 according to the present embodiment, the shielding layer 31 is formed so as to cover the G filter layer 20G and the B filter layer 20B. Although not shown, the shielding layer 31 also covers the R filter layer.

  That is, the shielding layer 31 is formed between the R filter layer, the G filter layer 20G, and the B filter layer 20B, and further formed on these filter layers. In this case, since the shielding layer 31 is formed on each filter layer, if the surface of the shielding layer 31 is flattened, the second planarizing layer is formed like the solid-state imaging device 12 according to the first embodiment. There is no need to form.

  Since the second planarization layer is not formed, light may enter the shielding layer 31 between the R filter layer, the G filter layer 20G, and the B filter layer 20B. When such light is condensed on the photodiode 18, color mixing occurs. Therefore, in order to make it difficult for light that has entered the shielding layer 31 to reach the photodiode 18, in the case of the solid-state imaging device 30 according to the second embodiment, the first planarization layer 19 has a lower refraction than the shielding layer 31. It is necessary to form by the rate material.

  As shown in FIG. 11, such a solid-state imaging device 30 is formed after the grooves 26 are formed between the G filter layer 20G and the B filter layer 20B and between the G filter layer 20G and the R filter layer. As shown in FIG. 14, a shielding layer 31 may be formed on the G filter layer 20G, the B filter layer 20B, and the R filter layer including the inside of the groove 26.

  Even in such a solid-state imaging device 30 according to this embodiment and a camera module to which the solid-state imaging device 30 is applied, the refractive index lower than these filter layers is between the R filter layer, the G filter layer 20G, and the B filter layer 20B. The shielding layer 31 is formed of a material having Therefore, color mixing can be suppressed for the same reason as in the solid-state imaging device 12 and the camera module 10 according to the first embodiment. In addition, shading is improved. In particular, in a camera module to which the solid-state imaging device 30 is applied, color mixing can be suppressed and shading can be improved without increasing costs.

  Although the embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  For example, the shielding layer 21 according to the first embodiment or the shielding layer 31 according to the second embodiment may be applied to a surface irradiation type solid-state imaging device. Here, the surface irradiation type solid-state imaging device includes a wiring layer formed on the surface of a semiconductor substrate, and a G filter layer, a B filter layer, and an R filter layer formed on the wiring layer. A microlens is formed on the G filter layer, the B filter layer, and the R filter layer.

DESCRIPTION OF SYMBOLS 10 ... Camera module 11 ... Circuit board 12, 30 ... Solid-state imaging device 13 ... Lens holder 14 ... Lens 15 ... Infrared cut off filter 16 ... Micro lens 17 ... Semiconductor Substrate 18... Photodiode 19... First planarization layer 20 G... Green color filter layer (G filter layer)
20B ... Blue color filter layer (B filter layer)
20R Red color filter layer (R filter layer)
21, 31 ... shielding layer 21 '... shielding material 22 ... second planarization layer 23 ... oxide film 24 ... wiring layer 24a ... wiring 24b ... interlayer insulating film 25 27 ... resist layers 25a, 27a ... openings 26 ... grooves

Claims (8)

A semiconductor substrate having a plurality of photodiodes;
A first planarization layer formed on the semiconductor substrate;
A plurality of color filter layers formed on the first planarization layer so as to be spaced apart from each other;
A shielding layer made of a material having a refractive index lower than that of the color filter layer and having a refractive index higher than that of the first planarization layer, which is formed so as to fill between these color filter layers;
A second planarization layer made of a material having a higher refractive index than the shielding layer, formed on the plurality of color filter layers including the shielding layer;
A plurality of microlenses formed on the second planarization layer;
A wiring layer formed on the back surface of the semiconductor substrate;
A solid-state imaging device comprising: A semiconductor substrate having a plurality of photodiodes;
A plurality of color filter layers formed on the semiconductor substrate so as to be separated from each other,
A shielding layer made of a material having a refractive index lower than that of the color filter layer formed between the color filter layers;
A plurality of microlenses formed on the plurality of color filter layers including the shielding layer;
A solid-state imaging device comprising:   The solid-state imaging device according to claim 2, wherein the shielding layer is formed so as to fill a space between the plurality of color filter layers. Further comprising a first planarizing layer between the semiconductor substrate and the plurality of color filter layers including the shielding layer,
A second planarizing layer formed of a material having a higher refractive index than the shielding layer is further provided between the plurality of color filter layers including the shielding layer and the plurality of microlenses. The solid-state imaging device according to claim 2.   The solid-state imaging device according to claim 4, wherein the first planarization layer is formed of a material having a lower refractive index than the shielding layer. A flattening layer formed of a material having a lower refractive index than the shielding layer between the semiconductor substrate and the plurality of color filter layers including the shielding layer;
The solid-state imaging device according to claim 2, wherein the shielding layer is further formed between the plurality of color filter layers and the plurality of microlenses.   The solid-state imaging device according to claim 2, further comprising a wiring layer on a back surface of the semiconductor substrate. A semiconductor substrate having a plurality of photodiodes;
A plurality of color filter layers formed on the semiconductor substrate so as to be separated from each other,
A shielding layer made of a material having a refractive index lower than that of the color filter layer formed between the color filter layers;
A plurality of microlenses formed on the plurality of color filter layers including the shielding layer;
A solid-state imaging device comprising:
A cylindrical lens holder that is arranged so as to cover the solid-state imaging device and has a lens that collects light on the solid-state imaging device,
A camera module comprising:

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