JP4957564B2 - Solid-state imaging device and imaging apparatus using the same - Google Patents

Description

  The present invention relates to a solid-state imaging device and an imaging device, and more particularly to a solid-state imaging device that prevents occurrence of crosstalk and sensitivity reduction, and an imaging device that uses 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 CCDs and CMOSs. However, with the advancement of semiconductor technology, the pixels of the solid-state image sensors have been further miniaturized, and the cameras themselves have been downsized. In such a solid-state imaging device, a color filter and a microlens for increasing the amount of light incident on the light receiving unit and improving the sensitivity are provided corresponding to the light receiving unit of each pixel. FIG. 10 is a diagram showing the arrangement of each color filter constituting the color filter of such a solid-state imaging device, and FIG. 11 is a cross-sectional view showing the color filter and the microlens taken along line II in FIG. 12 is a cross-sectional view showing the color filter and the microlens taken along line II-II in FIG. As shown in the figure, the color filter 51 is formed on the planarization layer 52, and is formed by arranging rectangular red filters 51R, green filters 51G, and blue filters 51B. A microlens 55 is disposed on the color filter 51 via a planarizing layer 53. The rectangular red filter 51R, green filter 51G, and blue filter 51B constituting the color filter 51 are adjacent to each other, but the corners are rounded, and therefore there are voids V. . In such a void portion V, no filter of any color exists or only partially exists, so that light rays incident on this portion are not appropriately separated, and the void portion V There is a problem that the light is refracted at the interface and becomes stray light, resulting in crosstalk and the like. Further, the surface of the flattening layer 53 on the gap V is also uneven, which causes a problem such as deformation of the microlens formed on the flattening layer 53. Such deformation of the microlens is performed when the arrangement pitch of the color filter and the arrangement pitch of the microlens are changed (shading correction) in order to prevent a reduction in sensitivity (shading) around the effective imaging area of the solid-state imaging device. Furthermore, it becomes more remarkable.

In order to prevent such voids from occurring, for example, a color filter is formed so as not to cause voids by adjusting the dimensions of the mask pattern light-shielding portions corresponding to positive color resists and performing overexposure. In addition, it has been proposed to fill a corner with one of the color filters in contact with each corner (Patent Document 1).
JP 2006-269775 A

However, in the above-described method, it is necessary to control the ultraviolet irradiation energy for appropriate overexposure, and it is necessary to have an illuminance distribution in the ultraviolet irradiation in order to make the edge portion of the color filter into a tapered shape. There was a problem that process management was complicated.
In the above-described method, the corner portion is filled with a filter of any one color by using a mask having a minute light-shielding pattern at the corner portion as a mask used for exposure of the positive color resist. However, the degree of reduction in contrast at the time of exposure at the corners differs between the green filter present in a checkered pattern and the other two color filters. For this reason, the use of a mask having a minute light-shielding pattern at the corners may not prevent the generation of voids, and conversely, the corners are raised and formed on the color filter. There is also a problem that irregularities are generated on the surface of the flattening layer, causing deformation of the microlens and the like.

On the other hand, it is also possible to fill the voids generated in the color filter by increasing the thickness of the flattening layer interposed between the color filter and the microlens. However, when the flattening layer is thickened, the distance from the lower surface of the microlens array to the light receiving portion is increased, and in the present situation where miniaturization is required such that the size of one pixel of the solid-state imaging device is 1 to 2 μm, Generation of crosstalk of oblique incident light from the lens (for example, light incident on the red filter of the color filter enters the light receiving unit corresponding to the blue filter or green filter) or sensitivity reduction (originally should be incident on the light receiving unit) The problem arises that the light beam is scattered by a metal electrode or the like and the amount of incident light is reduced).
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a solid-state imaging device that prevents occurrence of crosstalk and sensitivity reduction and an imaging apparatus using the same.

In order to achieve such an object, a solid-state imaging device of the present invention includes a plurality of light receiving units arranged two-dimensionally at a constant pitch, and a rectangular red filter, a green filter corresponding to each of the light receiving units, The microlens comprising at least a color filter in which blue filters are arranged and a microlens array in which a plurality of microlenses are two-dimensionally arranged corresponding to each of the light receiving units, From the center to the periphery of the effective imaging area, the displacement is increased with respect to the corresponding light receiving unit, and the planar shape of the microlens increases the displacement with respect to the corresponding light receiving unit. Thus with a shape that largely removed rectangular corners, not overlapped on the corner portions of the color filters constituting the color filter, the color Each color filter constituting the filter is arranged so that a deviation amount increases from the center to the periphery of the effective imaging region with respect to the corresponding light receiving unit, and the deviation amount is received by the corresponding microlens and the light receiving portion. It was set as the structure which is below the deviation | shift amount from a part.

As another aspect of the present invention, the microlens array is arranged directly on the color filter.
As another aspect of the present invention, the microlens array is disposed on the color filter via a flattening layer, and the thickness of the flattening layer is 0.3 μm or less.
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 does not overlap the corners of the color filters constituting the color filter, even if there are voids or raised portions at the corners of the color filters of the color filter. The microlens has a good shape without deformation. In addition, since the planar shape of the microlens is a shape obtained by removing the four corners of the rectangle, the variation in the lens surface curvature of the microlens is smaller than that in the case where the planar shape is a rectangle, and the light collection efficiency is improved. . In addition, the planarization layer existing between the color filter and the microlens array can be thinned, or the planarization layer can be omitted. As a result, the thickness from the lower surface of the microlens array to the light receiving portion is small, crosstalk is prevented, and good sensitivity is achieved.
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. In FIG. 1, a solid-state imaging device 1 includes a substrate 2 having a plurality of light receiving portions 3 and electrodes 4 provided at a constant arrangement pitch, and a light shielding layer 6 sequentially provided on the substrate 2 via an insulating layer 5, A passivation layer 7, a planarizing layer 8, a color filter 9, and a microlens array 10 are included.
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 electrode 4 transfers signal charges generated by the light receiving unit 3 that is a photodiode, and may have a light shielding film on the upper surface of the electrode 4 (microlens array 10 side).

The insulating layer 5 is made of, for example, a transparent film such as silicon oxide formed by the CVD method, and is formed so as to cover the light receiving unit 3 and the 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 is made of silicon nitride, silicon dioxide, or the like, and the planarization layer 8 can be formed of a resin material.
As shown in FIG. 2, the color filter 9 includes a rectangular red filter 9 </ b> R, a green filter 9 </ b> G, and a blue filter 9 </ b> B, and these color filters correspond to the light receiving units 3. The green filter 9G constituting the color filter 9 is a non-isolated filter in which corner portions are in contact and arranged in a checkered pattern. Further, the red filter 9R and the blue filter 9B are isolated filters arranged in a portion where the green filter 9G is not formed. In the illustrated example, the color filter 9 has a gap V at a portion where the corners of the color filters are in contact.

  The microlens array 10 includes a plurality of microlenses 11 formed corresponding to the color filters of the light receiving portions 3 and the color filters 9. FIG. 3 is a partial plan view for explaining the microlens array 10. The light receiving unit 3 is indicated by a two-dot chain line, each color filter of the color filter 9 is indicated by a chain line, the microlens 11 is indicated by a solid line, and other constituent members are omitted. ing. As shown in FIG. 3, the microlenses 11 constituting the microlens array 10 are arranged with a deviation from the corresponding light receiving units 3. In the present invention, the planar shape of the microlens 11 is a shape in which the four corners of the rectangle are removed, and is not superimposed on the corner portion 9 a of each color filter constituting the color filter 9. The purpose of providing a deviation in the arrangement of the microlenses 11 with respect to the light receiving portions 3 is for the purpose of performing shading correction, and with respect to the corresponding light receiving portions 3 from the center of the effective imaging region toward the periphery. It arrange | positions so that deviation | shift amount may become large. However, it is assumed that there is no deviation between the light receiving unit 3 and the microlens 11 at the center of the effective imaging region. Further, the change in the shift amount of the microlens 11 with respect to the corresponding light receiving unit 3 from the center to the periphery of the effective imaging region may be gradually increased or may be increased stepwise. Furthermore, an area where the amount of deviation gradually increases may be provided in the boundary area that increases stepwise. In FIG. 3, the direction indicated by the arrow a is the center of the effective imaging area.

  In the example shown in FIGS. 1 to 3, each color filter constituting the color filter 9 is arranged at the same pitch as the light receiving unit 3, but each color filter constituting the color filter is also effective for shading correction. It may be arranged so that the amount of deviation with respect to the corresponding light receiving unit 3 increases from the center to the periphery of the imaging region. FIG. 4 is a partial plan view corresponding to FIG. 3 showing such an example. Also in this example, the planar shape of the microlens 11 is a shape in which the four corners of the rectangle are removed, and is not superimposed on the corners 9 a of the color filters constituting the color filter 9. The center C2 of the color filter and the center C3 of the microlens 11 are offset from the center C1 of the light receiving unit 3 in each pixel. In this case, the shift amount of the center C2 of the color filter with respect to the center C1 of the light receiving unit 3 is set to be equal to or less than the shift amount of the center C3 of the microlens 11 with respect to the center C1 of the light receiving unit 3. In the center of the effective imaging area, the color filter 9 and the micro lens 11 are not displaced with respect to the corresponding light receiving unit 3. In addition, the change in the shift amount of the color filter 9 and the microlens 11 with respect to the corresponding light receiving unit 3 from the center to the periphery of the effective imaging region may be gradually increased or increased stepwise. Further, an area where the amount of deviation gradually increases may be provided in the boundary area that increases stepwise.

  The planar shape of the microlens 11 is not particularly limited as long as it is a shape obtained by removing the four corners of the rectangle as described above and does not overlap the corners 9 a of the color filters constituting the color filter 9. FIG. 5 is a diagram showing an example of the planar shape of the microlens constituting the solid-state imaging device of the present invention. The octagonal shape (FIG. 5 (A)) as in the above-described example, and the four corners that are rectangular rather than the octagonal shape. A shape with a small removal (FIG. 5B) or a shape with a larger removal of the four corners of the rectangle than the octagonal shape (FIG. 5C) may be used. Further, it may be a hexagonal shape (FIG. 5D), a shape removed by rounding four corners of a rectangle (FIG. 5E), or a circular shape (FIG. 5F). Further, the microlenses 11 constituting the microlens array 10 may have two or more planar shapes. For example, it is good also as a planar shape which removed the four corners of a rectangle largely as the deviation | shift amount with respect to the corresponding light-receiving part 3 becomes large.

Thus, by making the planar shape of the microlens 11 into a shape in which the four corners of the rectangle are removed, the variation in the lens surface curvature of the microlens 11 is reduced, and the light collection efficiency is improved. That is, as shown in FIG. 6A, in the case of a microlens having a rectangular planar shape, the cross-sectional shape at L1 and the cross-sectional shape at L2 are those shown in FIG. 6B, and the lens surface curvature of both is large. There is a difference. On the other hand, in the planar microlens from which the four corners of the rectangle are removed as shown in FIG. 6C, the cross-sectional shape at L1 and the cross-sectional shape at L2 are as shown in FIG. The difference in curvature of the lens surface is small.
Here, the method of forming the microlens array 10 including the microlenses 11 is not particularly limited. For example, a positive photoresist is used as the microlens material, and after the photolithography process of coating, exposure, and development, the photoresist Can be post-baked and melted to form a convex lens. An example of one pixel for a microlens photomask used in this molding method is as shown in FIG. In FIG. 7, one pixel 21 includes a light shielding portion 22 and a light transmitting portion 23 around the light shielding portion 22. The light shielding portion 22 has a shape in which the four corners of the rectangle are removed. In the illustrated example, the light shielding portion 22 has a regular octagonal shape. For example, the microlens having a planar shape as described above with reference to FIGS. Is formed in a corresponding shape.

In the solid-state imaging device 1 of the present invention as described above, since the microlens 11 does not overlap with the corners 9a of the color filters constituting the color filter 9, a gap or a raised portion is generated at the corners of the color filters of the color filter. Even so, the microlens 11 has a good shape without deformation. Further, since the planar shape of the microlens 11 is a shape in which the four corners of the rectangle are removed, the variation in the lens surface curvature in the microlens 11 is smaller than that in the case where the planar shape is rectangular, and the light collection efficiency is improved. It will be a thing. Further, the microlens array 10 can be directly provided on the color filter 9. As a result, the thickness from the lower surface of the microlens array 10 to the light receiving portion 3 is small, crosstalk is prevented, and good sensitivity is achieved.
The above-described embodiment of the solid-state imaging device is an exemplification, and the present invention is not limited to this embodiment. For example, the microlens array 10 may be disposed on the color filter 9 via a planarizing layer. As described above, the microlens 11 is not affected even if a gap or a raised portion is generated at the corner of each color filter of the color filter, and therefore, the color filter 9 and the microlens array 10 are not affected. It is possible to reduce the thickness of the interposed flattening layer. For example, the thickness of the planarization layer is preferably 0.3 μm or less.

[Imaging device]
FIG. 7 is a schematic cross-sectional view showing an embodiment of the imaging apparatus of the present invention. In FIG. 7, an imaging device 31 of the present invention includes a substrate 33 including the solid-state imaging device 32 of the present invention, a sealing member 34 disposed outside the solid-state imaging device 32, and the sealing member 34. And a protective material 35 disposed to face the solid-state imaging device 32 with a desired gap. The solid-state imaging device 32 is connected to an external terminal 38 via a wiring 36 and front and back conductive vias 37. Such a ceramic package type image pickup device 31 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. 8 is a schematic sectional view showing another embodiment of the imaging apparatus of the present invention. An imaging device 41 of the present invention shown in FIG. 8 is an example of a mobile phone camera module, and includes a substrate 43 provided with the solid-state image sensor 42 of the present invention, and a sealing member disposed outside the solid-state image sensor 42. 44, an infrared cut filter 45 disposed so as to face the solid-state imaging device 42 with a desired gap, a lens barrel 46 disposed on the infrared cut filter 45, and the inside of the lens barrel 46 The lens unit 47 attached to the lens is provided. Such an image pickup apparatus 41 can be reduced in size and thickness because the solid-state image pickup element 42 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 the solid-state image pickup element may be used. 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 2.0 μm and a pixel number of 2592 × 1944 was prepared.
Next, a planarization layer, a color filter, and a microlens array were formed on the wafer as described below.
(Formation of 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, ultraviolet exposure, and post-baking to obtain a planarization layer (thickness). 0.3 μm) was formed.

(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.
In the order of formation of G, R, and B, the above materials are spin-coated, and an RGB color filter (thickness 0.8 μm) is formed by performing pre-baking, exposure with a 1/5 reduction type i-line stepper, development, and post-baking. did. 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 2.0 μm similarly to the pixel light receiving unit.
In addition, as a result of observing the formed color filter using an atomic force microscope, it was confirmed that a space | gap part (depth of about 0.5 micrometer) exists in a corner | angular part.

(Formation of microlenses)
On the color filter, spin coating MFR401L made by JSR Co., Ltd. as a microlens material, pre-baking, exposure with a 1/5 reduction type i-line stepper, development, post-exposure, post-baking melt flow, microlens Formed. A 1.19% solution of TMAH (tetramethylammonium hydroxide) was used as the developer.
In the photomask used in the above exposure, the light shielding portion 22 in FIG. 7 has a regular octagonal shape with a side of 0.704 μm, and the arrangement pitch of the regular octagonal light shielding portions in the X and Y directions is the pixel light receiving portion pitch (2 0.0.mu.m) was subjected to a fine scaling of 99.993% to provide a photomask having a shift amount with respect to the pixel light receiving portion pitch (2.0 .mu.m).
As a result of observing the microlens thus formed on the color filter using an atomic force microscope, the microlens is not superimposed on the corner of each color filter constituting the color filter, and no deformation or the like is observed. It was confirmed to be a good lens.

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. The thickness from the lower surface of the microlens array to the photodiode (light receiving portion) in this solid-state imaging device was 4.3 μm.

[Example 2]
After forming the color filter, a solid-state imaging device was fabricated in the same manner as in Example 1 except that a planarization layer was formed as described below and a microlens was formed on the planarization layer.
(Formation of planarization layer)
A photo-curing acrylic transparent resin material (CT-2020L manufactured by Fuji Microelectronics Materials Co., Ltd.) is applied onto the color filter by spin coating, followed by pre-baking, ultraviolet exposure, and post-baking to form an upper planarizing layer ( A thickness of 0.1 μm) was formed.
As a result of observing the microlens formed on the planarizing layer in the same manner as in Example 1, it was confirmed that the microlens was a good lens without deformation.
In addition, the thickness from the lower surface of the microlens array to the photodiode (light receiving portion) in this solid-state imaging device is thicker than the first embodiment by the thickness of the newly provided flattening layer (0.1 μm). Met.

[Comparative Example 1]
A solid-state imaging device was manufactured in the same manner as in Example 1 except that the photomask used in the exposure for forming the microlens was a photomask in which the light shielding portion 22 was a square having a side of 1.7 μm in FIG. .
As a result of confirming the microlens formed on the color filter, the microlens is superimposed on the corner of each color filter constituting the color filter and exists at this corner outside the 600th pixel from the center of the effective imaging region. Deformation affected by the gaps was observed.

[Comparative Example 2]
The color filter was formed in the same manner as in Comparative Example 1.
Next, a photo-curing acrylic transparent resin material (CT-2020L manufactured by Fuji Microelectronics Materials Co., Ltd.) is spin-coated so as to cover this color filter, and then pre-baking, UV exposure, and post-baking are performed. And a planarization layer (0.4 μm) was formed. The thickness of the flattening layer was set to the minimum thickness that would not cause deformation on the surface of the formed flattening layer under the influence of the voids at the corners of the color filters of the color filter.
Next, a microlens was formed on the planarizing layer in the same manner as in Comparative Example 1 to produce a solid-state imaging device.
In this solid-state imaging device, the microlens was observed in the same manner as in Example 1. As a result, it was confirmed that the microlens was a good lens without deformation. However, the thickness from the lower surface of the microlens array to the photodiode (light receiving portion) was 4.7 μm, which was thicker than those in Examples 1 and 2.

  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 figure which shows an example of the color filter which comprises the solid-state image sensor of this invention. It is a figure for demonstrating an example of arrangement | positioning of the micro lens, color filter, and light-receiving part which comprise the solid-state image sensor of this invention. It is a figure for demonstrating the other example of arrangement | positioning of the microlens, color filter, and light-receiving part which comprise the solid-state image sensor of this invention. It is a figure which shows one pattern of the photomask shown by FIG. 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 figure for demonstrating the variation in the lens surface curvature of a microlens. It is a figure which shows one pixel part for the photomask for microlenses. 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. It is a figure which shows arrangement | positioning of each color filter which comprises the color filter of a solid-state image sensor. It is sectional drawing which shows the color filter and micro lens in the II line | wire of FIG. It is sectional drawing which shows the color filter and micro lens in the II-II line | wire of FIG.

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 ... Flattening layer 9 ... Color filter 9G ... Green filter 9R ... Red filter 9B ... Blue filter 10 ... Microlens array 11 ... Microlens 31, 41 ... Imaging device

Claims (4)

Corresponding to a plurality of light receiving portions arranged two-dimensionally at a constant pitch, a color filter in which rectangular red filters, green filters and blue filters are arranged in correspondence with the respective light receiving portions, and the individual light receiving portions. And at least a microlens array in which a plurality of microlenses are two-dimensionally arranged,
Microlenses constituting the microlens array, toward the periphery from the center of the effective image pickup area is disposed so as deviation amount with respect to the corresponding light receiving portion is increased, and the planar shape of the microlens, The shape is such that the four corners of the rectangle are largely removed as the amount of deviation with respect to the corresponding light receiving portion increases, and it is not superimposed on the corner of each color filter constituting the color filter ,
Each color filter constituting the color filter is arranged so that a shift amount increases with respect to a corresponding light receiving unit from the center to the periphery of the effective imaging region, and the shift amount corresponds to the corresponding microlens. A solid-state imaging device characterized in that the amount is less than or equal to a deviation between the light receiving portion and the light receiving portion . The solid-state imaging device according to claim 1 , wherein the microlens array is directly disposed on the color filter. 2. The solid-state imaging device according to claim 1, wherein the microlens array is disposed on the color filter via a planarization layer, and the planarization layer has a thickness of 0.3 μm or less. . An imaging apparatus comprising the solid-state imaging device according to claim 1 .

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