JP2009194186A - Solid-state imaging element and imaging apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state imaging element and an imaging apparatus using the same by which the focal distance for each color light becomes uniform and color shading is suppressed. <P>SOLUTION: A solid-state imaging element 1 has a lower planarization layer 8, a color filter 9, an upper planarization layer 10, and a microlens array 11. A relation nr>ng≥nb is provided among refractive indexes nr, ng and nb in main wavelength, in respective color filters 9G, 9R and 9B for red, green and blue. These refractive indexes nr, ng and nb are larger than the refractive index of the upper planarization layer in a corresponding wavelength. A relation nMLb>nMLg>nMLr is provided among refractive indexes nMLr, nMLg and nMLb of respective color main wavelength for red, green and blue of a microlens 12. A relation Db1>Dg1>Dr1 is provided among center part film thicknesses Dr1, Dg1 and Db1 of the respective color filters for red, green and blue. These refractive indexes nMLr, nMLg and nMLb are set to be larger than the refractive index of the upper planarization layer in the corresponding wavelength. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device and an imaging device, and more particularly, to a solid-state imaging device in which a plurality of light receiving units and minute condensing lenses (microlenses) are arranged, and an imaging device using the solid-state imaging device.

  In recent years, digital cameras and video cameras that capture still images and moving images have become widespread in various fields. These cameras use solid-state image sensors such as CCD and CMOS. The structure of such a solid-state imaging device is, for example, a light-shielding layer, a passivation layer, a lower planarization layer, a color filter, an upper planarization layer, and a micro-layer via an insulating layer on a substrate on which a light receiving portion and a metal electrode are formed. A lens array is provided. As the semiconductor technology advances, the pixels of the solid-state imaging device are further miniaturized, and the camera itself is becoming smaller. For example, the average size of one pixel of the solid-state imaging device is 5 to 6 μm, and is 1 to 2 μm when it is smaller. As the pixels become finer, the sensitivity decreases as the thickness from the bottom surface of the microlens array to the light receiving part decreases when the oblique incident light from the camera lens is considered. Light to be emitted by a metal electrode and the amount of incident light is reduced), shading (decrease in sensitivity at the periphery of the effective imaging area), color shading (sensitivity difference for each color of the color filter at the periphery of the effective imaging area) This is advantageous in that the increase in the However, considering the roles of the main body of the lower planarizing layer, the color filter, and the upper planarizing layer, it is difficult to reduce the thickness or omit it, and to reduce the thickness from the bottom surface of the microlens array to the light receiving portion. There is a limit.

In addition, when the same shape microlens is arranged in each color filter consisting of a red filter, a green filter, and a blue filter having the same thickness, the light collecting property is derived from the wavelength dependence of the refractive index of the microlens material. It decreases in the order of blue, green and red. Therefore, the focal length at the red dominant wavelength is longer than the focal length at the green dominant wavelength, and the focal length at the blue dominant wavelength is shorter than the focal length at the green dominant wavelength, facilitating color shading. It will be.
On the other hand, by setting the thickness of the red, green, and blue color filters of the color filters corresponding to the light receiving portions of each color light so that red>green> blue, the sensitivity reduction in the solid-state image sensor is suppressed, and the color balance is adjusted. Improvement has been proposed (Patent Documents 1 and 2). In addition, it has been proposed to correct the chromatic aberration for each color filter of the color filter by setting the boundary surface shape of the medium having a refractive index difference above the light receiving portion to be different for each color (Patent Document 3). .
JP-A-7-38075 JP 2002-94037 A Japanese Patent Laid-Open No. 2006-19588

However, in conventional solid-state imaging devices as disclosed in Patent Documents 1 to 3, a microlens is formed on a color filter set to have a different thickness for each color filter, or a surface shape (micrometer) is set for each color filter. Since the microlens is formed on the color filter that is set to have a different shape (boundary surface shape with the lens), the flatness of the surface on which the microlens is formed is poor. Therefore, the shape and characteristics of the microlens are red, green, There is a problem in that each color of blue is different, and thus a difference in light collecting property is increased or sensitivity is lowered.
The present invention has been made in view of the above situation, and an object of the present invention is to provide a solid-state imaging device in which the focal length for each color light is uniform and color shading is suppressed, and an imaging apparatus using the same. And

  The present invention focuses on the fact that the focal length of the microlens for each color changes due to the wavelength dependence of the refractive index of the microlens and the difference in refractive index at each principal wavelength of each color filter of the color filter, This is made by paying attention to the condensing facilitating function of the microlens by the upper planarization layer interposed between the microlens and the color filter.

  That is, the solid-state imaging device of the present invention includes a plurality of light receiving portions arranged in a two-dimensional manner, a lower planarization layer, and a red filter, a green filter, and a blue filter corresponding to each of the light receiving portions. A two-dimensional arrangement of a plurality of microlenses on the upper planarizing layer corresponding to each of the light receiving portions. A refractive index ng at the red dominant wavelength of the red filter, a refractive index ng at the green dominant wavelength of the green filter, and a refractive index nb at the blue dominant wavelength of the blue filter. , Nr> ng ≧ nb, and the refractive indexes ng, ng, nb are larger than the refractive index of the upper planarizing layer at the corresponding wavelength, and the central film of the red filter There is a relationship of Db1> Dg1> Dr1 between Dr1, the central film thickness Dg1 of the green filter, and the central film thickness Db1 of the blue filter, and the refractive index nMLr at the red dominant wavelength of the microlens, the green main There is a relationship of nMLb> nMLg> nMLr between the refractive index nMLg at the wavelength and the refractive index nMLb at the blue main wavelength, and the refractive indexes nMLr, nMLg, and nMLb are the refractions of the upper planarization layer at the corresponding wavelengths. The configuration was larger than the rate.

As another aspect of the present invention, the central film thickness Dr1 and the peripheral film thickness Dr2 of the red filter, the central film thickness Dg1 and the peripheral film thickness Dg2 of the green filter, and the central film thickness Db1 of the blue filter The peripheral film thickness Db2 is set to have a relationship of Db2-Db1>Dg2-Dg1> Dr2-Dr1.
The imaging device of the present invention is configured to include the above-described solid-state imaging device of the present invention.

In such a solid-state imaging device of the present invention, since the microlens is disposed on the color filter via the upper planarization layer, the shape of the microlens is uniform and the characteristics are uniform. The relationship of the refractive index at each color dominant wavelength of each color filter constituting, the relationship between this refractive index and the refractive index of the upper flattening layer, the relationship of the refractive index at each color dominant wavelength of the microlens, and the color filter constituting each color filter Since the relationship between the film thickness is specific, the function of promoting the condensing property of the microlens by the upper planarization layer also works appropriately for each color light, and the position of the focus for each color light is aligned. The light condensing property for each color is uniform, and color shading and sensitivity reduction are suppressed.
The image pickup apparatus of the present invention has a high quality with little loss of vignetting caused by oblique incidence and a low efficiency distribution with respect to the amount of incident light, and can be reduced in size and thickness.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Solid-state imaging device]
FIG. 1 is a schematic configuration diagram showing an embodiment of a solid-state imaging device of the present invention. FIG. 2 is a schematic configuration diagram showing a color filter, an upper planarizing layer, and a microlens constituting the solid-state imaging device shown in FIG. In FIG. 1, a solid-state imaging device 1 includes a substrate 2 including a plurality of light receiving units 3 and transfer electrodes 4 that are two-dimensionally arranged at a constant arrangement pitch, and a light shield that is sequentially provided on the substrate 2 via an insulating layer 5. It has a layer 6, a passivation layer 7, a lower planarization layer 8, a color filter 9, an upper planarization layer 10, and a microlens array 11.

The substrate 2 is a silicon substrate, and the light receiving unit 3 may be a known photodiode having a pn junction, and is usually arranged in a square lattice shape. The transfer electrode 4 is for transferring a signal charge generated by the light receiving unit 3 that is a photodiode, and may include a light shielding film on the upper surface of the transfer electrode 4 (on the microlens array 11 side).
The insulating layer 5 is made of, for example, a transparent film such as silicon oxide formed by a CVD method, and is formed so as to cover the light receiving unit 3 and the transfer electrode 4. The light shielding layer 6 has a plurality of openings arranged corresponding to the individual light receiving portions 3 and may be formed of a light shielding metal layer (for example, Al, Al / Si / Cu alloy). it can. The passivation layer 7 can be formed of silicon nitride, silicon dioxide, or the like, and the lower planarization layer 8 can be formed of a resin material. The insulating layer 5 and the lower planarization layer 8 have such a degree that the wavelength dependence of the refractive index can be almost ignored. The passivation layer 7 has a wavelength dependency of the refractive index. However, since the film thickness is as thin as about 0.2 μm, the influence on the light condensing property of the microlens can be ignored.

The color filter 9 is an array of rectangular red filters 9R, green filters 9G, and blue filters 9B. These color filters correspond to the respective light receiving units 3. In the present invention, it is essential that the following requirements are satisfied in the red filter 9R, the green filter 9G, and the blue filter 9B that constitute the color filter 9. That is, there is a relationship of nr> ng ≧ nb between the refractive index ng at the red dominant wavelength of the red filter 9R, the refractive index ng at the green dominant wavelength of the green filter 9G, and the refractive index nb at the blue dominant wavelength of the blue filter 9B. To establish. Further, the refractive indexes nr, ng, and nb are larger than the refractive index of the upper planarization layer 10 at the corresponding wavelength. Further, as shown in FIG. 2, Db1>Dg1> Dr1 among the central film thickness Dr1 of the red filter 9R, the central film thickness Dg1 of the green filter 9G, and the central film thickness Db1 of the blue filter 9B. A relationship is established.
In the present invention, the refractive index is measured with a spectroscopic ellipsometer.

  The upper planarizing layer 10 covers the color filter 9 having a different thickness for each color filter to form a flat surface, thereby enabling the formation of a microlens array 11 composed of homogeneous microlenses having the same light collecting property. In addition, the function of promoting the light condensing property of the microlens is exhibited. The refractive index of the upper planarizing layer 10 at the red dominant wavelength, the refractive index at the green dominant wavelength, and the refractive index at the blue dominant wavelength are the refractive indices nr, ng, nb at the corresponding wavelengths in the color filter 9 as described above. Smaller than that. Such an upper planarization layer 10 can be formed of a resin material. It should be noted that the refractive index of the upper planarizing layer 10 at the red dominant wavelength, the refractive index at the green dominant wavelength, and the refractive index at the blue dominant wavelength are such that wavelength dependence can be almost ignored.

  The microlens array 11 includes a plurality of microlenses 12 formed corresponding to the color filters of the light receiving portions 3 and the color filters 9. A relationship of nMLb> nMLg> nMLr is established among the refractive index nMLr at the red dominant wavelength, the refractive index nMLg at the green dominant wavelength, and the refractive index nMLb at the blue dominant wavelength of the microlens 12. Further, the refractive indexes nMLr, nMLg, and nMLb in the microlens 12 are larger than the refractive index of the upper planarizing layer 10 at the corresponding wavelength. The method for forming the microlens array 11 including the microlenses 12 is not particularly limited. For example, a positive photoresist is used as a microlens material, and after the photolithography steps of coating, exposure, and development, the photoresist is post-baked. Can be melted and molded into a convex lens shape.

Here, the light condensing property of the solid-state imaging device 1 of the present invention will be described.
First, external light incident on the microlens array 11 is collected by each microlens 12. As described above, the relationship of nMLb>nMLg> nMLr is established among the refractive index nMLr at the red dominant wavelength, the refractive index nMLg at the green dominant wavelength, and the refractive index nMLb at the blue dominant wavelength of the microlens 12. Therefore, when comparing the focal length of the microlens 12 for each dominant wavelength (for example, red dominant wavelength = 620 nm, green dominant wavelength = 540 nm, blue dominant wavelength = 450 nm), red> green as shown in FIG. > Blue relationship.

  The light transmitted through the microlens 12 is transmitted through the upper planarization layer 10, but the refractive indexes nMLr, nMLg, and nMLb of the microlens 12 at each color dominant wavelength are higher than the refractive index of the upper planarization layer 10 at the corresponding wavelength. large. Therefore, the light transmitted through the upper planarization layer 10 is further collected. That is, the light beam collected by the microlens 12 is refracted according to the refractive index difference at the interface between the microlens 12 and the upper flattening layer 10, but the refractive indices nMLr, nMLg, Since nMLb is larger than the refractive index of the upper planarization layer 10 at the corresponding wavelength, the refraction angle is increased and the light condensing property is further improved. As described above, the upper planarizing layer 10 exhibits the function of promoting the light condensing property of the microlens 12. As described above, the relationship Db1> Dg1> Dr1 is established among the central film thickness Dr1 of the red filter 9R, the central film thickness Dg1 of the green filter 9G, and the central film thickness Db1 of the blue filter 9B. To do. Therefore, when comparing the thickness of the upper flattening layer 10 positioned on each color filter, the relationship of the upper flattening layer on the red filter> the upper flattening layer on the green filter> the upper flattening layer on the blue filter It becomes. Therefore, the light condensing facilitating function of the microlens 12 by the upper flattening layer 10 is also the largest by the upper flattening layer 10 on the red filter 9R, and then by the upper flattening layer 10 on the green filter 9G. Due to the upper planarizing layer 10 on the blue filter 9B, it becomes smaller. When comparing the focal lengths of the respective main wavelengths transmitted through the upper planarizing layer 10 as shown in FIG. 4, the relationship of red> green> blue is obtained, and the order is the same as FIG. Due to the difference in the light condensing facilitating function of the microlens 12 by the upper planarizing layer 10, the difference in focal length is reduced as compared with the case where the microlens 12 is transmitted (FIG. 3).

  The light transmitted through the upper planarizing layer 10 passes through the red filter 9R, the green filter 9G, and the blue filter 9B that constitute the color filter 9. As described above, nr> ng ≧ the refractive index ng at the red dominant wavelength of the red filter 9R, the refractive index ng at the green dominant wavelength of the green filter 9G, and the refractive index nb at the blue dominant wavelength of the blue filter 9B. While the relationship of nb is established, the refractive indexes ng, ng, and nb are larger than the refractive index of the upper planarization layer 10 at the corresponding wavelength. Therefore, the light incident on the color filter 9 from the upper planarizing layer 10 tends to be condensed. As described above, the relationship Db1> Dg1> Dr1 is established among the central film thickness Dr1 of the red filter 9R, the central film thickness Dg1 of the green filter 9G, and the central film thickness Db1 of the blue filter 9B. To do. Therefore, the above-described tendency of reducing the light collecting property is the largest in the thickest blue filter 9G, and then in order of the green filter 9G and the red filter 9R. Comparing the focal lengths of the respective main wavelengths transmitted through the color filter 9 as described above, they are the same or slightly different as shown in FIG.

Thereafter, each color light sequentially passes through the lower planarization layer 8, the passivation layer 7, and the insulating layer 5, but the refractive index of the lower planarization layer 8 and the insulating layer 5 is such that wavelength dependence is almost negligible. Although the layer 7 has a wavelength dependency of the refractive index, the film thickness is as thin as about 0.2 μm, and therefore the influence on the light condensing property of the microlens can be ignored. For this reason, the relationship (the same or a slight difference) between the focal lengths of the respective color lights achieved at the stage of transmission through the color filter 9 is maintained. Therefore, the focus positions of the respective color lights reaching the light receiving layer 3 are aligned, and thereby the light collecting property for each color becomes uniform, and the color shading and sensitivity reduction are suppressed.
FIG. 6 is a schematic configuration diagram corresponding to FIG. 2 showing another embodiment of the solid-state imaging device of the present invention. In this embodiment, the central film thickness Dr1 and the peripheral film thickness Dr2 of the red filter 9R, the central film thickness Dg1 and the peripheral film thickness Dg2 of the green filter 9G, the central film thickness Db1 and the peripheral film of the blue filter 9B. A relationship of Db2-Db1>Dg2-Dg1> Dr2-Dr1 is established with the thickness Db2. As a result, the tendency of reducing the light collecting property in the red filter 9R described above is reduced, and conversely, the tendency of reducing the light collecting property in the blue filter 9G is increased, so that the state shown in FIG. The focal length can be corrected more accurately to the state shown.

  The color filter 9 as shown in FIG. 6 can be formed as follows, for example. First, a photosensitive material for a green filter is applied on the lower planarizing layer 8, exposed through a desired mask, developed, and arranged in a checkered pattern with corners in contact as shown in FIG. The green filter 9G (shown with hatching in FIG. 10) is formed (FIG. 9A). Next, a red filter photosensitive material 9'R is applied so as to cover the green filter 9G (FIG. 9B). The photosensitive material 9′R for the red filter applied in this way is likely to have a concave surface due to the effect of a step due to the green filter 9G existing around it. Then, by exposing and developing the photosensitive material 9′R for the red filter using a photomask that expresses the gradation with a fine dot pattern that does not resolve at the exposure wavelength, a red filter having a convex surface 9R is formed (FIG. 9C). FIG. 11 is a diagram showing an example of such a dot pattern, which has 20 × 20 dots expressed on an area for one pixel. In this example, a black part is a light shielding part, and a white part is a light transmission part. Next, a blue filter photosensitive material 9'B is applied so as to cover the red filter 9R and the green filter 9G (FIG. 9D). The blue filter photosensitive material 9'B applied in this manner is also affected by the surrounding green filter 9G, but the blue filter photosensitive material 9'B has a film thickness of the green filter 9G. When the thickness is larger than the thickness, the surface tends to be flat without being concave. Therefore, the blue filter photosensitive material 9'B is exposed and developed using a photomask obtained by inverting the light-shielding portion and the light transmission portion in one pixel of the photomask shown in FIG. It is easy to form the blue filter 9B having a concave surface (FIG. 9E).

  Further, the color filter 9 as shown in FIG. 6 can be formed as follows. First, a photosensitive material for a red filter is applied on the lower planarizing layer 8, and red using a photomask as shown in FIG. 11 in which gradation is expressed by a fine dot pattern that does not resolve at the exposure wavelength. By exposing and developing the photosensitive material for the filter, the red filter 9R having a convex surface is formed. Next, a photosensitive material for a green filter is applied so as to cover the red filter 9R. At this time, the part where the green filter 9G is formed is not completely surrounded by the red filter 9R, and the green filter 9G is coated with a thicker film than the red filter 9R, so that the photosensitive material itself is coated. Leveling effect works and it is applied almost flatly. Then, it is exposed through a desired mask and developed to form a checkered green filter 9G. Next, a photosensitive material for a blue filter is applied so as to cover the red filter 9R and the green filter 9G. The photosensitive material for blue filter applied in this manner is affected by the surrounding green filter 9G, but when the film thickness of the photosensitive material for blue filter is larger than the film thickness of the green filter 9G, The surface is not concave and tends to be flat. For this reason, the photosensitive material for the blue filter is exposed and developed using a photomask obtained by inverting the light shielding portion and the light transmitting portion in one pixel of the photomask shown in FIG. A concave blue filter 9B is formed.

The cross-sectional shape of each color filter that satisfies the relationship of Db2-Db1>Dg2-Dg1> Dr2-Dr1 is not limited to the cross-sectional shape of each color filter shown in FIG. For example, as shown in FIG. 7, the surface of the red filter 9R (upper flattening layer 10 side, the same in the following description) is made flat, the surface of the green filter 9G is concave, and the surface of the blue filter 9B is further It may be a concave cross-sectional shape. Further, as shown in FIG. 8, the blue filter 9B may have a flat surface, the green filter 9G may have a convex shape, and the red filter 9R may have a convex shape.
The above-described embodiment of the solid-state imaging device is an exemplification, and the present invention is not limited to this embodiment.

[Imaging device]
FIG. 12 is a schematic cross-sectional view showing an embodiment of the imaging apparatus of the present invention. In FIG. 12, the imaging device 21 of the present invention includes a substrate 23 provided with the solid-state imaging element 22 of the present invention, a sealing member 24 disposed outside the solid-state imaging element 22, and the sealing member 24. And a protective material 25 disposed to face the solid-state imaging device 22 with a desired gap. The solid-state image sensor 22 is connected to an external terminal 28 via a wiring 26 and front and back conductive vias 27. Such a ceramic package type imaging device 21 can be used for various digital cameras, video cameras, and the like, and the sensitivity, size, and thickness of the camera can be reduced.

FIG. 12 is a schematic cross-sectional view showing another embodiment of the imaging apparatus of the present invention. An imaging device 31 of the present invention shown in FIG. 12 is an example of a camera module for a mobile phone, and includes a substrate 33 provided with the solid-state image sensor 32 of the present invention, and a sealing member disposed outside the solid-state image sensor 32. 34, an infrared cut filter 35 disposed so as to face the solid-state imaging device 32 with a desired gap, a lens barrel 36 disposed on the infrared cut filter 35, and the inside of the lens barrel 36 The lens unit 37 attached to the is provided. Such an image pickup apparatus 31 can be reduced in size and thickness because the solid-state image pickup device 32 of the present invention is subjected to shading correction and has high sensitivity.
The image pickup apparatus of the present invention is not limited to the above-described embodiment, and any structure that includes the solid-state image pickup element of the present invention as a solid-state image pickup element may be used, and the configurations of various conventional image pickup apparatuses may be employed as they are. it can.

Next, an Example is shown and this invention is demonstrated further in detail.
[Example 1]
First, a wafer on which a CMOS sensor composed of photodiodes having a pixel light receiving portion pitch of 5.7 μm and a pixel number of 2592 × 1944 was prepared.
Next, a lower planarization layer, a color filter, an upper planarization layer, and a microlens array were formed on the wafer as described below.

(Formation of lower planarization layer)
A photo-curing acrylic transparent resin material (CT-2020L manufactured by Fuji Microelectronics Materials Co., Ltd.) is spin-coated on the passivation layer, followed by pre-baking, UV exposure, and post-baking to form a lower planarizing layer ( A thickness of 1.2 μm) was formed. With respect to the lower planarizing layer, the refractive index at each principal wavelength (red dominant wavelength = 620 nm, green dominant wavelength = 540 nm, blue dominant wavelength = 450 nm) was measured. As a result, the refractive index at the red dominant wavelength and the green dominant wavelength was 1. The refractive index at the blue dominant wavelength was 1.52, and the wavelength dependence was negligible.

(Formation of color filter)
The following materials were prepared as negative photosensitive red materials (R materials), green materials (G materials), and blue materials (B materials).
Material for R: SR-4000L manufactured by Fuji Microelectronic Materials Co., Ltd.
Material for G: SG-4000L manufactured by Fuji Microelectronic Materials Co., Ltd.
Material for B: SB-4000L manufactured by Fuji Microelectronic Materials Co., Ltd.
The above materials were spin-coated in the order of formation of G, R, and B, and pre-baking, exposure with a 1/5 reduction type i-line stepper, development, and post-baking were performed to form a color filter. That is, first, a G material is applied onto the lower planarizing layer, exposed and developed, and then post-baked (220 ° C., 10 minutes) to obtain a green filter with a flat checkered surface (the film thickness at the central portion). 1.0 μm) was formed. Next, an R material is applied so as to cover this green filter, and a gradation is expressed by a fine dot pattern that does not resolve at the exposure wavelength (a level higher than that of the photomask as shown in FIG. 11). After exposure and development using a weakened photomask, post baking (220 ° C., 10 minutes) was performed to form a red filter (central film thickness 0.7 μm) with a flat surface. Next, the B material is applied so as to cover the red filter and the green filter, and a photomask (one pixel of the photomask shown in FIG. 11) in which gradation is expressed by a fine dot pattern that does not resolve at the exposure wavelength. The light shielding part and the light transmitting part in the photomask are reversed and exposed to light and developed, and then post-baked (220 ° C., 10 minutes) to obtain a blue filter with a flat surface (Central part film thickness 1.3 μm) was formed. As a result, a color filter as shown in FIGS. 1 and 2 was formed.

As a developing solution, a 50% diluted solution of CD-2000 manufactured by Fuji Microelectronic Materials Co., Ltd. was used. Further, the arrangement pitch of the color filters was set to 5.7 μm similarly to the pixel light receiving portion.
About each color filter of the formed color filter, the refractive index in each main wavelength (red main wavelength = 620 nm, green main wavelength = 540 nm, blue main wavelength = 450 nm) was measured. As a result, the red filter had a refractive index nr = 1.70 at the red dominant wavelength, the green filter had a refractive index ng = 1.60 at the green dominant wavelength, and the blue filter had a refractive index nb = 1.55 at the blue dominant wavelength. .

(Formation of upper planarization layer)
A photocurable acrylic transparent resin material (CT-2020L, manufactured by Fuji Microelectronics Materials Co., Ltd.) is spin-coated on the passivation layer, followed by pre-baking, ultraviolet exposure, and post-baking to form an upper planarizing layer. Formed. The thickness of the formed upper planarizing layer is 1.3 μm on the red filter, 1.0 μm on the green filter, and 0.7 μm on the blue filter. The upper surface of the upper planarizing layer (a microlens is formed in a later step) Surface) had good flatness. Moreover, as a result of measuring the refractive index at each of the main wavelengths (red main wavelength = 620 nm, green main wavelength = 540 nm, blue main wavelength = 450 nm), the refractive index at the red main wavelength and the green main wavelength was measured. Was 1.51, the refractive index at the blue dominant wavelength was 1.52, and the wavelength dependence was negligible.

(Formation of microlenses)
MFR401L made by JSR Co., Ltd. as a microlens material is spin-coated on the upper planarizing layer, and pre-baking, exposure with a 1/5 reduction type i-line stepper, development, post-exposure, and post-baking melt flow are performed. A lens (height 1.23 μm) was formed. A 1.19% solution of TMAH (tetramethylammonium hydroxide) was used as the developer.
The photomask used in the above exposure was designed such that a microlens pattern was arranged by applying a fine scaling of 99.9887% around the center of the effective imaging area to the pixel light receiving portion pitch of 5.7 μm.

Next, the bonding pad portion was opened. That is, a positive resist (i-line positive resist PFI-27 manufactured by Sumitomo Chemical Co., Ltd.) is spin-coated, and after pre-baking, exposure and development are performed using a photomask having a pattern corresponding to the bonding pad portion and the scribe portion. went. As a result, a resist pattern having openings in the bonding pad portion and the scribe portion was formed, and oxygen ashing was performed using this resist pattern as a mask, and the planarizing layer on the portion was removed by etching. Next, the positive resist was removed using a resist stripping solution.
Next, the wafer was diced and package assembled to produce the solid-state imaging device of the present invention.
As a result of measuring the sensitivity difference between each color light of red, green, and blue by combining the F2.8 camera lens with the solid-state imaging device thus manufactured, it was 1.1% at a principal ray incident angle of 0 °. It was 0.7% at a light incident angle of 10 °, and it was confirmed that color shading was suppressed.

[Example 2]
A solid-state imaging device was produced in the same manner as in Example 1 except that the color filter was formed as follows.
(Formation of color filter)
Using the same material as in Example 1, spin-coating the above materials in the order of formation of G, R, and B, performing pre-baking, exposure with a 1/5 reduction type i-line stepper, development, and post-baking, A color filter was formed. That is, first, a G material is applied onto the lower planarizing layer, exposed and developed, and then post-baked (220 ° C., 10 minutes) to obtain a green filter with a flat checkered surface (the film thickness at the central portion). 1.0 μm) was formed. Next, an R material is applied so as to cover this green filter, and exposure and development are performed using a photomask as shown in FIG. 11 in which gradation is expressed by a fine dot pattern that does not resolve at the exposure wavelength. After that, post-baking (220 ° C., 10 minutes) is performed, and the red filter having a convex surface (central film thickness 0.7 μm, peripheral film thickness 0.61 μm at a radius of 2.85 μm from the central part) Formed. Next, the B material is applied so as to cover the red filter and the green filter, and a photomask (one pixel of the photomask shown in FIG. 11) in which gradation is expressed by a fine dot pattern that does not resolve at the exposure wavelength. After exposure and development using a photomask in which the light shielding part and the light transmission part are reversed, post-baking (220 ° C., 10 minutes) is performed, and a blue filter having a concave surface (film thickness of the central part 1. 3 μm and a peripheral portion film thickness of 1.50 μm at a radius of 2.85 μm from the central portion). As a result, a color filter as shown in FIG. 6 was formed.

  As a result of combining the F2.8 camera lens with the solid-state imaging device thus manufactured and measuring the sensitivity difference between the red, green, and blue color lights, the principal ray incident angle is 0%, which is 0.1%. It was 0.4% at a light incident angle of 10 °, and it was confirmed that color shading was further suppressed as compared with Example 1.

[Comparative Example 1]
A solid-state imaging device was formed in the same manner as in Example 1 except that the color filters were formed so that each color filter had a thickness of 1.0 μm, and an upper planarizing layer having a thickness of 1.0 μm was formed on the color filter. Produced.
As a result of combining the F2.8 camera lens with the solid-state imaging device thus fabricated and measuring the sensitivity difference between the red, green, and blue color lights, the principal ray incident angle is 0%, which is 1.6%. It was 1.1% at a light incident angle of 10 °, and it was confirmed that color shading occurred.

[Comparative Example 2]
A solid-state imaging device was fabricated in the same manner as in Example 1 except that the red filter and the blue filter constituting the color filter were replaced (formed with a red filter thickness of 1.3 μm and a blue filter thickness of 0.7 μm).
As a result of measuring the sensitivity difference between each color light of red, green, and blue by combining the F2.8 camera lens with the solid-state imaging device thus manufactured, it was 2.1% at a chief ray incident angle of 0 °. It was 1.4% at a light incident angle of 10 °, and it was confirmed that color shading occurred.

[Comparative Example 3]
Using a microlens material (MFR401L, manufactured by JSR Corporation) as a material for forming the upper planarization layer, the refractive indexes at wavelengths of 450 nm, 540 nm, and 620 nm are 1.62, 1.61, and 1.60, respectively. A solid-state imaging device was produced in the same manner as in Example 1 except that a flattening layer was formed.
As a result of measuring the sensitivity difference between each color light of red, green, and blue by combining the F2.8 camera lens with the solid-state imaging device thus manufactured, it was 3.0% at a principal ray incident angle of 0 °. It was 2.4% at a light incident angle of 10 °, and it was confirmed that color shading occurred.

  The present invention can be applied to various fields in which a small and highly reliable solid-state imaging device and imaging device are required.

It is a schematic block diagram which shows one Embodiment of the solid-state image sensor of this invention. It is a schematic block diagram which shows the color filter, upper planarization layer, and micro lens which comprise the solid-state image sensor shown by FIG. It is a figure for demonstrating the condensing property of each color main wavelength light in a microlens. It is a figure for demonstrating the condensing property of each color main wavelength light in a micro lens and an upper planarization layer. It is a figure for demonstrating the condensing property of each color main wavelength light in a micro lens, an upper planarization layer, and a color filter. It is a figure for demonstrating the planar shape of the microlens which comprises the solid-state image sensor of this invention. It is a schematic block diagram equivalent to FIG. 2 which shows other embodiment of the solid-state image sensor of this invention. It is a schematic block diagram equivalent to FIG. 2 which shows other embodiment of the solid-state image sensor of this invention. It is a schematic block diagram equivalent to FIG. 2 which shows other embodiment of the solid-state image sensor of this invention. It is a figure which shows one pixel part for the photomask for microlenses. It is process drawing explaining an example of the formation method of the color filter which comprises the solid-state image sensor of this invention. It is a top view which shows the example of the green filter of the color filter which comprises the solid-state image sensor of this invention. It is a figure for demonstrating the photomask for color filter formation. It is a figure for demonstrating an example of the imaging device of this invention. It is a figure for demonstrating the other example of the imaging device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Solid-state image sensor 2 ... Board | substrate 3 ... Light-receiving part 4 ... Electrode 5 ... Insulating layer 6 ... Light shielding layer 7 ... Passivation layer 8 ... Lower planarization layer 9 ... Color filter 9G ... Green filter 9R ... Red filter 9B ... Blue filter 10 ... Upper planarization layer 11 ... Microlens array 12 ... Microlens 21,31 ... Imaging device

Claims (3)

A plurality of light receiving portions arranged two-dimensionally, a lower flattening layer, a color filter in which a red filter, a green filter, and a blue filter are arranged in the lower flattening layer corresponding to each of the light receiving portions; And an upper planarizing layer disposed so as to cover the color filter, and a microlens array in which a plurality of microlenses are two-dimensionally arranged on the upper planarizing layer in correspondence with each of the light receiving portions. ,
There is a relationship of nr> ng ≧ nb between the refractive index ng at the red dominant wavelength of the red filter, the refractive index ng at the green dominant wavelength of the green filter, and the refractive index nb at the blue dominant wavelength of the blue filter, And the refractive indices nr, ng, nb are larger than the refractive index of the upper planarization layer at the corresponding wavelength,
There is a relationship of Db1>Dg1> Dr1 between the central film thickness Dr1 of the red filter, the central film thickness Dg1 of the green filter, and the central film thickness Db1 of the blue filter.
Between the refractive index nMLr at the red dominant wavelength, the refractive index nMLg at the green dominant wavelength, and the refractive index nMLb at the blue dominant wavelength of the microlens, there is a relationship of nMLb>nMLg> nMLr, and the refractive indices nMLr, nMLg, nMLb is larger than the refractive index of the said upper planarization layer in a corresponding wavelength, The solid-state image sensor characterized by the above-mentioned.   The central film thickness Dr1 and the peripheral film thickness Dr2 of the red filter, the central film thickness Dg1 and the peripheral film thickness Dg2 of the green filter, and the central film thickness Db1 and the peripheral film thickness Db2 of the blue filter are Db2. 2. The solid-state imaging device according to claim 1, wherein a relationship of −Db <b> 1> Dg <b> 2-Dg <b> 1> Dr <b> 2-Dr <b> 1 is satisfied.   An imaging apparatus comprising the solid-state imaging device according to claim 1.

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