JP5440649B2 - Manufacturing method of solid-state imaging device - Google Patents

Description

  The present invention relates to a solid-state imaging device and an imaging apparatus, and more particularly to a method of manufacturing a solid-state imaging device that prevents occurrence of crosstalk and sensitivity reduction.

  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. In a conventional solid-state imaging device, the thickness from the bottom surface of the microlens array to the light receiving portion exceeds 5 μm, and as the above-mentioned pixel miniaturization proceeds, crosstalk of oblique incident light from the camera lens occurs. (For example, the light beam incident on the red filter of the color filter enters the light receiving unit corresponding to the blue filter or the green filter) or the sensitivity decreases (the light beam that should be incident on the light receiving unit is originally emitted by the metal electrode or the like, and the incident light amount is Will become a problem. As described above, when the solid-state imaging device having a stacked structure is viewed in cross section, the thickness from the light receiving surface in the vertical direction (stacking direction) to the lower surface of the microlens through the color filter with respect to the horizontal pixel size. Is large, various adverse effects on obliquely incident light occur.

On the other hand, for the purpose of reducing the cost in manufacturing a solid-state image sensor, improving the yield, and reducing the amount of light attenuation in the solid-state image sensor, it is proposed to directly form a color filter without providing a lower flattening layer. (Patent Document 1). In the solid-state imaging device having such a structure, the thickness from the color filter to the light receiving portion can be reduced.
In addition, the color filter is usually an array of rectangular red filters, green filters, and blue filters. Although the sides of adjacent filters are in contact with each other, the corners are rounded, so that the gaps are Department exists. Since there is no filter of any color in such a void, the light incident on the void is not properly separated, and is refracted at the gap interface to become stray light. There was a problem of causing talk and the like. Further, when the upper flattening layer is thin, the surface of the upper flattening layer is uneven due to the influence of the gap of the color filter, which is different from the arrangement pitch of the filters of each color constituting the color filter in the upper flattening layer. There is also a problem of causing deformation of the microlenses formed at the arrangement pitch. For this reason, it is necessary to increase the thickness of the upper planarization layer formed on the color filter, which causes a problem that the above-described crosstalk and sensitivity reduction are likely to occur.

  In order to prevent the generation of such voids, a color filter can be formed so as not to generate voids by adjusting the dimensions of the corresponding mask pattern light shielding portions of the positive color resist and performing overexposure. It has been proposed to fill the corners with any one of the color filters in contact with the corners (Patent Document 2).

JP 2002-217394 A JP 2006-269775 A

However, in the solid-state imaging device having the structure shown in Patent Document 1, since the color filter is formed on the uneven surface without providing the lower planarizing layer, the formed color filter surface is also uneven. Become. For this reason, considering the flatness of the surface on which the microlens array is formed, it is necessary to increase the thickness of the upper flattening layer formed on the color filter. Therefore, the thickness from the lower surface of the microlens array to the light receiving portion cannot be reduced, and the occurrence of crosstalk and sensitivity reduction as described above cannot be reduced.
Further, in the method disclosed in Patent Document 2, it is necessary to control the ultraviolet irradiation energy for appropriate overexposure, and the ultraviolet irradiation has an illuminance distribution in order to make the edge portion of the color filter into a tapered shape. There was a problem that process management was complicated.

Further, in the above-described method, the corner portion is filled with a filter of any one color by using a mask provided with a fine 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, in some cases, it is not possible to prevent the generation of voids by simply using a mask having a minute light-shielding pattern at the corners. On the other hand, swells occur at the corners, causing irregularities on the surface of the upper planarization layer formed on the color filter, causing deformation of the microlens, etc., and upper planarization to avoid this There was also a problem that the thickness of the layer had to be increased.
The present invention has been made in view of the above circumstances, and a manufacturing method of a solid-state imaging device in which the thickness from the lower surface of the microlens array to the light receiving portion is reduced to prevent occurrence of crosstalk and sensitivity reduction. The purpose is to provide.

In order to achieve such an object, the present invention provides a microlens comprising a planarizing layer, a color filter disposed on the planarizing layer, and a plurality of microlenses disposed on the color filter. In the method of manufacturing a solid-state imaging device including an array and a plurality of light receiving portions corresponding to the microlenses below the planarizing layer, a color filter is formed by using a photosensitive material for a green filter on the planarizing layer. Applying, exposing and developing using a green filter photomask to form a non-isolated rectangular green filter, applying a red filter photosensitive material, and using a red filter photomask A process of forming an isolated rectangular red filter by exposure and development, a photosensitive material for blue filter is applied, and exposure and development are performed using a blue filter photomask to isolate the filter. Forming a rectangular blue filter, and the green filter photomask uses a photomask having a rectangular pattern with corners cut off, and the red filter photomask and the blue filter For photomasks, use a photomask with a rectangular pattern with a sub-pattern at the corners, and use the maximum distance from the intersection of the rectangular sides to the corner cutouts as the cutout dimensions. When the maximum length of the sub-pattern protruding outward from the sub-pattern dimension is taken as the sub-pattern dimension, the notch dimension and the sub-pattern dimension are set to dimensions that are less than the resolution limit of the exposure apparatus under the mask exposure conditions . .

  In such a manufacturing method of the present invention, in a green filter photomask having a rectangular pattern with corners notched, the notches provided in the corners moderately reduce the exposure amount from both adjacent patterns. Therefore, it is possible to form a non-isolated green filter whose corners are in sharp contact with each other, and in a red filter photomask and a blue filter photomask having a rectangular pattern having a sub-pattern at the corners. Since the sub-pattern suppresses the decrease in contrast during exposure at the corners, it is possible to form isolated red and blue filters with rounded and sharp corners. Color filters with excellent flatness can be formed by suppressing the occurrence of voids and bulges between the filters. Even when the microlens is directly provided on the surface, the applied microlens forming material is leveled to form a good microlens without deformation, and therefore, the thickness from the bottom surface of the microlens array to the light receiving portion. Therefore, it is possible to manufacture a solid-state imaging device that can prevent occurrence of crosstalk and a decrease in sensitivity.

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 the photomask for microlens formation. It is a partial top view which shows an example of the photomask for green filters arranged in a non-isolated manner. It is a figure which shows one pattern of the photomask shown by FIG. It is a figure which shows the other example of the photomask for filters arranged in a non-isolated manner. It is a figure which shows the other example of the photomask for filters arranged in a non-isolated manner. It is a partial top view which shows an example of the photomask for red filters arranged in isolation. It is a figure which shows one pattern of the photomask shown by FIG. It is a figure which shows the other example of the photomask for filters arranged in isolation. It is a figure which shows the other example of the photomask for filters arranged in isolation. It is a figure which shows the other example of the photomask for filters arranged in isolation. It is process drawing for demonstrating formation of the color filter in the manufacturing method of the solid-state image sensor of this invention. 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.

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 layer such as silicon oxide formed by a 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. The color filter 9 has a height difference of 0.25 μm or less between a portion where the surface on the microlens array 10 side is the most convex and a portion where the boundary between the filters of each color is the most concave. is there. The roughness of the color filter surface in the present invention is measured using an atomic force microscope or a scanning electron microscope (SEM).
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.

  In such a solid-state imaging device 1 of the present invention, since there is no planarization layer between the color filter 9 and the microlens array 10, the thickness from the lower surface of the microlens array 10 to the light receiving unit 3 is small. For example, the thickness is less than 5 μm. Further, the surface of the color filter 9 is excellent in flatness because the height difference between the most convex part and the most concave part of the boundary between filters of each color is 0.25 μm or less. Therefore, the microlenses 11 provided directly on the color filter 9 have a good shape without deformation even when the arrangement pitch is different from the arrangement pitch of the filters of the respective colors constituting the color filter 9. As a result, the solid-state imaging device 1 is prevented from crosstalk of oblique incident light rays and has good sensitivity. Of course, the present invention does not exclude the case where the arrangement pitch of the microlenses 11 is the same as the arrangement pitch of the filters of the respective colors constituting the color filter 9.

  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, a planarization layer may be interposed between the color filter 9 and the microlens array 10 in order to further improve the flatness of the surface of the color filter 9. Also in this case, since the flatness of the surface of the color filter 9 is excellent, the thickness of the flattening layer can be in the range of 0.1 to 0.25 μm, and the thickness from the lower surface of the microlens array 10 to the light receiving unit 3. A thickness of less than 5 μm can be maintained.

[Method for Manufacturing Solid-State Imaging Device]
An embodiment of the method for manufacturing a solid-state imaging device of the present invention will be described by taking the manufacturing of the solid-state imaging device 1 as an example.
First, the light receiving portion 3 and the electrode 4 are formed on the substrate 2. The light receiving portion 3 made of a photodiode can be formed by a known method using, for example, an n-type silicon substrate as the substrate 2. The electrode 4 can be formed by forming a desired conductive film and patterning it.
Next, a transparent layer made of silicon oxide or the like is formed by CVD to form the insulating layer 5 so as to cover the light receiving portion 3 and the electrode 4. In the formation of the insulating layer 5, planarization may be performed by CMP (Chemical Mechanical Polishing) after film formation.

Next, the light shielding layer 6 is formed on the insulating layer 5 so as to have an opening in the light receiving region of the light receiving unit 3. The light shielding layer 6 is formed by, for example, forming a light shielding metal layer (for example, Al, Al / Si / Cu alloy, etc.), applying a positive photosensitive resist on the metal layer, exposing, After a resist pattern is formed by a development photolithography process, the metal layer is etched using the resist pattern as a mask to form an opening to obtain a light shielding layer.
Next, a passivation layer 7 is formed so as to cover the light shielding layer 6. The passivation layer 7 can be formed, for example, by forming a silicon nitride film, a silicon dioxide film or the like by the CVD method. Thereafter, a planarizing layer 8 is formed by applying a resin material on the passivation layer 7 by spin coating.
Next, a color filter 9 is formed on the planarizing layer 8, and a microlens 11 is directly formed on the color filter 9 to form a microlens array 10.
The formation of the color filter 9 is a characteristic step of the manufacturing method of the present invention, and will be described later in detail.

Although there is no restriction | limiting in particular as a formation method of the microlens 11, For example, a positive photoresist is used as a microlens material, and after a photolithographic process of application | coating, exposure, and development, the photoresist is post-baked and melted to form a convex lens. The method of forming can be mentioned. The microlens formation method that melts and forms a convex lens in this way is a formation method that always requires a gap between the microlenses. As an efficient method of forming microlenses with no gaps between microlenses, photo is produced using a gradation photomask that represents the three-dimensional shape of the microlens with gradation, with a fine dot pattern that does not resolve at the exposure wavelength. A method of exposing and developing the resist can be used. FIG. 3 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. By exposing and developing through a gradation photomask having such a dot pattern, the shape expressed in gradation by fine dots can be transferred to the photoresist layer to form the microlens 11.
As will be described later, in order to further improve the flatness of the surface of the color filter 9, the microlens 11 may be formed after the planarization layer is formed.

  Next, a method for forming the color filter 9 will be described. In the present invention, the color filter 9 is formed by coating a photosensitive material for a green filter on the planarizing layer 8, exposing and developing using a photomask for a green filter, and forming a non-isolated rectangular green filter. A step of forming 9G, a step of applying a photosensitive material for a red filter, exposing and developing using a photomask for red filter, and forming an isolated rectangular red filter 9R; And applying a photosensitive material, exposing and developing using a photomask for blue filter, and forming an isolated rectangular blue filter 9B. Then, a photomask having a rectangular pattern with corners cut out is used as a green filter photomask, and a rectangular pattern having a sub-pattern at the corners is used as a red filter photomask and a blue filter photomask. A photomask having the same is used. Note that the pattern and sub-pattern that the photomask in the present invention has is a light transmitting portion when a negative photosensitive material is used to form the red filter 9R, the green filter 9G, and the blue filter 9B. In the case of using a type photosensitive material, it is a light shielding part. The same applies to the following description.

First, a photomask used for forming a color filter in the present invention will be described.
FIG. 4 is a partial plan view showing a photomask for the green filter 9G arranged in a non-isolated manner, and FIG. 5 is a diagram showing one pattern of the photomask shown in FIG. 4 and 5, the photomask 21G is provided with a rectangular pattern 22G in a checkered pattern, and each rectangular pattern 22G has a notch 23 at four corners 22a.

  Here, a conventional photomask in which rectangular patterns are arranged in a non-isolated manner in contact with corners will be described. In such a photomask in which rectangular patterns are arranged non-isolated with the corners in contact, the contrast reduction during exposure at the corners is different from that in a photomask in which rectangular patterns are arranged in isolation. ing. That is, in a photomask in which rectangular patterns are arranged in a non-isolated manner in contact with corners, the corners are exposed from both patterns, and therefore there is no proximity pattern in the reduction in contrast at the corner exposure. This is less than the decrease in contrast during exposure at the corners of the rectangular pattern. For this reason, it is formed by exposure and development using a photomask (a photomask in which rectangular patterns are arranged in a non-isolated manner in contact with the corners) without the corner notch 23 as described above. When a negative photosensitive material is used, the filter is thickly connected at the corners. When a positive photosensitive material is used, the corners are separated from each other. Even in this case, a sharp rectangular filter cannot be formed. However, in the present invention, by using the photomask 21G, the notch 23 provided in the corner 22a serves to moderately suppress the exposure amount of the corner 22a exposed from both adjacent patterns. . Thereby, the non-isolated green filter 9 in which the corners are in sharp contact can be formed.

Note that the notch 23 of each pattern 22G has a notch dimension L that is the maximum distance L in the X-axis direction and the Y-axis direction from the intersection P extending from the rectangular side to the notch of the corner 22a. In addition, the notch dimension L is set to a dimension not more than the resolution limit of the exposure apparatus under the mask exposure conditions. When the cutout dimension L is larger than the resolution limit, the shape of the cutout portion 23 is directly reflected in the filter shape, and a sharp rectangular green filter cannot be obtained. Further, the lower limit of the notch dimension L can be about 40 nm (dimension when projected onto the object to be exposed), for example, when exposure by an i-line stepper is used.
In the above example, the cutout portion 23 has a shape in which the corner portion 22a is cut out linearly, but is not limited to this. For example, the cutout portion 23 has a shape as shown in FIGS. May be.

FIG. 8 is a partial plan view showing a photomask for the red filter 9R arranged in isolation, and FIG. 9 is a diagram showing one pattern of the photomask shown in FIG. 8 and 9, the photomask 21R includes a rectangular pattern 22R, and each rectangular pattern 22R has a rectangular sub-pattern 24 at four corners 22a.
By using the photomask 21R having the sub-pattern 24 at the corner 22a of the rectangular pattern 22R arranged in this way, the sub-pattern 24 suppresses a decrease in contrast during exposure at the corner. Therefore, it is possible to form an isolated red filter 9R that is not round and has sharp corners.

  The sub-pattern 24 included in each pattern 22R has a sub-pattern dimension L ′ when the maximum length of the sub-pattern protruding outward from the corners in the X-axis direction and the Y-axis direction is the sub-pattern dimension L ′. Is a dimension that is not more than the resolution limit of the exposure apparatus under the mask exposure conditions. Further, when the maximum distance that the sub pattern 24 protrudes outward from the corner 22a of the rectangular pattern 22R is defined as the protrusion distance d, the protrusion distance d is also a dimension that is less than the resolution limit of the exposure apparatus under the mask exposure conditions. To do. If the sub-pattern dimension L ′ or the protrusion distance d exceeds the resolution limit, when the photosensitive material to be used is a negative type, the exposure amount of the corner 22a becomes excessive, and the formed filter is The corner has a protruding shape, and a sharp rectangular red filter cannot be obtained. Further, the lower limit of the sub-pattern dimension L ′ and the protrusion distance d can be set to about 40 nm (dimension when projected onto the object to be exposed), for example, when exposure using an i-line stepper is used.

As shown in FIG. 10, the sub pattern 24 may be provided apart from the pattern 22R. In this case, the distance d ′ between the pattern 22R and the sub-pattern 24 is preferably set to be equal to or less than the resolution limit of the exposure apparatus under the mask exposure conditions. If the distance d ′ is too large, the sub-pattern 24 is not preferable because the effect of suppressing the reduction in contrast at the time of exposure of the corner 22a by 24 cannot be obtained.
In the above example, the sub pattern 24 is rectangular, but the shape of the sub pattern 24 is not limited to this. For example, it may be a triangle as shown in FIG. 11A, and in this case as well, the sub-pattern 24 may be spaced from the pattern 22R as shown in FIG. 11B. The protrusion distance d and the separation distance d ′ are preferably within the above-described ranges. Further, the sub pattern 24 may be circular as shown in FIG. 12A, and in this case as well, the sub pattern 24 may be separated from the pattern 22R as shown in FIG. The protrusion distance d and the separation distance d ′ are preferably within the above-described ranges.
Note that the photomask 21B (not shown) for the blue filter 9B arranged in isolation can be configured in the same manner as the photomask 21R described above, and the description thereof is omitted here.

Next, an example of forming the color filter 9 using the above-described photomasks 21G, 21R, and 21B will be described with reference to FIG.
First, a photosensitive material for a green filter is applied onto the planarizing layer 8, and exposed and developed using a photomask 21G to form a non-isolated green filter 9G (FIG. 13A). The green filter 9G is a sharp rectangle with corners in contact with each other. Therefore, the non-formation part (isolated) of the green filter 9G is also a sharp rectangle.
Next, a photosensitive material for a red filter is applied so as to cover the green filter 9G, and is exposed and developed using a photomask 21R to form an isolated red filter 9R (FIG. 13B). . The red filter 9R has a rounded shape and a rectangular shape with sharp corners. Therefore, the non-formation part of the green filter 9G (formation part of the red filter 9R) suppresses the generation of voids. As shown in FIG.

Next, a photosensitive material for blue filter is applied so as to cover the green filter 9G and the red filter 9R, and is exposed and developed using a photomask 21B to form an isolated blue filter 9B (FIG. 13 ( C)). The blue filter 9B is a rectangle that is not rounded and has a sharp corner, and therefore, the non-formation part of the green filter 9G (formation part of the blue filter 9B) is suppressed from generating voids. As shown, it is filled with a blue filter 9B.
Thereby, it is composed of a rectangular green filter 9G, a red filter 9R, and a blue filter 9B, and the occurrence of voids and bulges between the filters of each color, particularly at the corners, is suppressed, and the most convex part of the surface Thus, the color filter 9 having a height difference of 0.25 μm or less from the most concave portion of the boundary between the filters of each color is obtained.
The formation order of the red filter 9R and the blue filter 9B may be reversed.

  In the above-described method for manufacturing a solid-state imaging device of the present invention, the microlenses 11 are directly provided on the color filter 9 with an arrangement pitch different from the arrangement pitch of the filters of each color constituting the color filter 9 without interposing a planarizing layer. However, the microlens 11 is not deformed. For example, in the method of forming the microlens 11 using the above-described gradation photomask, when the pixel size is 2 μm and the thickness from the lower surface of the microlens array 10 to the light receiving unit 3 is designed to be 4.6 μm, When the focal length of the microlens 11 is adjusted to 4.6 μm, the height of the microlens 11 becomes 0.53 μm, and the coating thickness of the microlens material is set to about 0.6 μm. The color filter 9 formed as described above has a height difference of 0.25 μm or less between the most convex part and the most concave part of the boundary between the filters of each color. Fine irregularities are absorbed by the leveling function of the microlens material, and the microlens 11 is not deformed. Of course, even if the color filter has a height difference of more than 0.25 μm from the most concave part of the boundary between filters of each color, the unevenness can be absorbed by increasing the coating thickness of the microlens material. It is possible to form a microlens without deformation. However, there arises a problem that the thickness from the lower surface of the microlens array 10 to the light receiving unit 3 is 5 μm or more, the control of the focal length of the microlens becomes difficult, and the light cannot be efficiently condensed on the light receiving unit 3.

Thus, according to the manufacturing method of the present invention, it is possible to reduce the thickness from the lower surface of the microlens array to the light receiving portion, and it is possible to manufacture a solid-state imaging device that prevents occurrence of crosstalk and sensitivity reduction. . The present invention does not exclude that the arrangement pitch of the microlenses 11 directly formed on the color filter 9 is the same as the arrangement pitch of the filters of the respective colors constituting the color filter 9.
The embodiment of the manufacturing method described above is an exemplification, and the present invention is not limited to this embodiment. For example, in order to further improve the flatness of the surface of the color filter 9, the microlens 11 may be formed after the planarization layer is formed on the color filter 9. In this case, since the surface of the color filter 9 is excellent in flatness, the thickness of the flattening layer formed on the color filter 9 can be extremely thin, for example, in the range of 0.1 to 0.25 μm. it can.

[Imaging device]
FIG. 14 is a schematic cross-sectional view showing an embodiment of the imaging apparatus of the present invention. In FIG. 14, 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. 15 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. 15 is an example of a camera module for a mobile phone, 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 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 was prepared on which a CMOS sensor having a pixel light receiving portion pitch of 2.0 μm and a pixel number of 2592 × 1944 pixels and having a thickness of 3.5 μm from the light receiving portion to the surface of the passivation layer was prepared.
(Formation of planarization layer)
Next, after cleaning the wafer surface with a spin scraper, a photo-curing acrylic transparent resin material (CT-2020L manufactured by Fuji Microelectronics Materials Co., Ltd.) is spin-coated, and then pre-baking, UV exposure, post Baking was performed to form a planarization layer (thickness 0.3 μm).

(Formation of color filter)
The following materials were prepared as negative photosensitive green materials (G materials), red materials (R materials), and blue materials (B materials).
Material for G: SG-4000L manufactured by Fuji Microelectronic Materials Co., Ltd.
Material for R: SR-4000L manufactured by Fuji Microelectronic Materials Co., Ltd.
Material for B: SB-4000L manufactured by Fuji Microelectronic Materials Co., Ltd.
Moreover, the arrangement pitch of each color filter of a color filter was 2.0 micrometers, and the photomask shown by FIG. 4 and FIG. 5 was prepared as a photomask for green filters. This photomask has a rectangular pattern (light transmission part) having a side of 2.0 μm, and a notch dimension L of a notch part of a right isosceles triangle shape at a corner of each pattern is 0.1 μm. I did it. The exposure apparatus was NSR-2505i14E2 (1/5 reduction type, manufactured by Nikon Corporation), and the resolution limit under the set exposure conditions was 0.35 μm. The dimension of the photomask is a dimension when projected onto the wafer by the exposure apparatus, and the same applies to the following description regarding the dimension of the photomask.

Moreover, the photomask shown by FIG. 8 and FIG. 9 was prepared as a photomask for red filters and blue filters. This photomask has a rectangular pattern (light transmission part) having a side of 2.0 μm and a rectangular sub pattern (light transmission part), the dimension L ′ of the sub pattern is 0.2 μm, and the protrusion distance d is The thickness was 0.23 μm.
Then, in the formation order of the green filter, red filter, and blue filter, the above materials are spin-coated, pre-baked, exposed with a 1/5 reduction type i-line stepper, developed, and post-baked, and then the green filter, red filter, A color filter (thickness 0.8 μm) composed of a blue filter was formed on the planarization layer. As a developing solution, a 50% diluted solution of CD-2000 manufactured by Fuji Microelectronic Materials Co., Ltd. was used.

  For the color filter formed as described above, the difference in height between the most convex part and the most concave part of the boundary between the filters of each color is measured with an atomic microscope (SII Nanotechnology Co., Ltd. L As a result of measurement under the following conditions using -trace), it was 0.22 μm, and it was confirmed that the flatness was good. The probe used was DF-40 manufactured by SII Nanotechnology, and the scanning mode was DFM.

(Measurement condition)
Scanner sensitivity X / Y / Z: 260.00 / 260.00 / 14.32 nm / V
Sensor Z: 971.91 nm / V
Cantilever constant: Spring constant 56.000 N / m
Torsional spring constant 100.0 N / m
Resonance frequency 327.00 kHz
Lever length 200.0 μm
Needle height 10.00 μm
Scanning mode: Single screen measurement Measurement data: Shape image (sensor signal)
Scanning area / frequency: 19.995 × 19.995 μm / 1.00Hz
Scanning center X / Y: 11876 / -14790 nm
Rotation angle: -1.0 °
Number of X data / Y data: 256/256
Amplitude decay rate: -0.098
Bias voltage: 0.000 V
I gain / P gain: 0.2000 / 0.0488
Low-pass / high-pass filter: 1.010 kHz / 0.000 Hz
Q curve gain: 1.00
Excitation voltage: 1.882 V
Resonance frequency: 343.039 kHz
Measurement frequency: 342.850 kHz
Vibration amplitude: 0.447 V
Q value: 642.105
Linearize: Finished (CL correction)
Filter / FFT: 0/0
Mask: Not yet

  When the most convex part of the color filter and the most concave part of the boundary between filters of each color can be determined by observation with a scanning electron microscope (SEM), a cross section connecting these two points The height difference between the most convex part of the color filter and the most concave part of the boundary between the filters of each color can also be measured by observing and measuring the size with SEM. In this case, it is preferable to use focused ion beam processing (FIB) to form the cross section.

(Formation of microlenses)
MFR401L manufactured by JSR Co., Ltd. as a microlens material is spin-coated on the color filter (film thickness 0.6 μm), and after pre-baking, 1/5 reduction type using a gradation photomask as shown in FIG. The i-line stepper was exposed, and development, post-exposure, and post-baking were performed to form a microlens. A 1.19% solution of TMAH (tetramethylammonium hydroxide) was used as the developer.
In the gradation photomask used in the above exposure, the arrangement pitch was 1.999 μm. As a result of observing the microlens thus formed on the color filter using an atomic force microscope, it was confirmed that the microlens was a good lens having a height of 0.53 μm and a focal length of 4.6 μm without any deformation. It was done.

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 4.6 μm.

[Example 2]
A photomask having a pattern shown in FIG. 7 is used as a photomask for a green filter, and a pattern and a sub-pattern shown in FIG. 12A are used as photomasks for a red filter and a blue filter. A solid-state imaging device was produced in the same manner as in Example 1 except that a color filter was formed using a photomask. The cutout dimension L of the notch in the green filter photomask is 0.15 μm, and the subpattern dimension L ′ in the red filter and blue filter photomask is 0.25 μm, and the protrusion distance d. Was 0.2 μm.
In the manufacture of this solid-state imaging device, the color filter formed on the flattening layer has the most convex portion of the color filter and the most concave portion of the boundary between the filters of each color, as in the first embodiment. As a result of measuring the difference in height from the region where it was, it was 0.23 μm, and it was confirmed that the flatness was good. Furthermore, as a result of observing the microlens formed on the color filter in the same manner as in Example 1, it was confirmed that the microlens was a good lens without deformation.
Further, the thickness from the lower surface of the microlens array to the photodiode (light receiving portion) in this solid-state imaging device was 4.6 μm, as in the first embodiment.

[Example 3]
Other than using positive photosensitive green material (G material), red material (R material), blue material (B material), and using photomask pattern and sub-pattern as light shielding part Similar to Example 1, except that a green filter photomask and a red filter and blue filter photomask were prepared and a color filter was formed using these photomasks. Thus, a solid-state imaging device was produced.
In the manufacture of this solid-state imaging device, the color filter formed on the flattening layer has the most convex portion of the color filter and the most concave portion of the boundary between the filters of each color, as in the first embodiment. As a result of measuring the difference in height from the region where it was, it was 0.23 μm, and it was confirmed that the flatness was good. Furthermore, as a result of observing the microlens formed on the color filter in the same manner as in Example 1, it was confirmed that the microlens was a good lens without deformation.
Further, the thickness from the lower surface of the microlens array to the photodiode (light receiving portion) in this solid-state imaging device was 4.6 μm, as in the first embodiment.

[Example 4]
A solid-state imaging device is manufactured in the same manner as in Example 1 except that a color filter is formed using a photomask having the pattern and sub-pattern shown in FIG. 10 as the photomask for the red filter and the blue filter. did. The subpattern dimension L ′ in the red filter and blue filter photomasks was 0.2 μm, and the separation distance d ′ was 0.05 μm.
In the manufacture of this solid-state imaging device, the color filter formed on the flattening layer has the most convex portion of the color filter and the most concave portion of the boundary between the filters of each color, as in the first embodiment. As a result of measuring the difference in height from the region where it was, it was 0.25 μm, and it was confirmed that the flatness was good. Furthermore, as a result of observing the microlens formed on the color filter in the same manner as in Example 1, it was confirmed that the microlens was a good lens without deformation.
Further, the thickness from the lower surface of the microlens array to the photodiode (light receiving portion) in this solid-state imaging device was 4.6 μm, as in the first embodiment.

[Comparative Example 1]
As the photomask for the green filter, a color filter was formed by using a photomask in which a rectangular pattern was arranged in a non-isolated manner without touching the corners and in contact with the corners. Similarly, a solid-state imaging device was produced.
As a result of observing the color filter formed on the flattening layer in the solid-state imaging device in the same manner as in Example 1, the corners of each green filter are thickly connected. The corners of the filters overlap, and there are raised portions (height of about 0.2 μm) at the corners. Similarly to the first embodiment, the most convex part of the color filter and each color As a result of measuring the height difference from the most concave portion of the boundary between filters, it was 0.45 μm, and it was confirmed that the flatness was poor. As a result of confirming the microlenses formed on the color filters, deformations affected by the rising of the corners of the red and blue filters were 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 (0.5 μm) was formed. The thickness of the flattening layer is different from that of Example 1 in the height difference between the most convex portion of the formed flattening layer and the most concave portion corresponding to the boundary between filters of each color. The thickness was measured in the same manner, and was set as the thickness necessary to be the same as the surface roughness (height difference) of the color filter of Example 1 (0.22 μm).
Next, a microlens was formed on the planarization layer in the same manner as in 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 5.1 μm, which was thicker than that in Example 1.

[Comparative Example 3]
As a green filter photomask, a color filter using a photomask in which the notch dimension L of the right-angled isosceles triangle notch is 0.4 μm exceeding the resolution limit (0.35 μm) of the exposure apparatus A solid-state imaging device was manufactured in the same manner as in Example 1 except that was formed.
In the manufacture of this solid-state imaging device, the color filter formed on the planarization layer was observed using an atomic force microscope, and as a result, it was confirmed that there were voids at the corners. In addition, as a result of measuring the height difference between the most convex part of the color filter and the most concave part of the boundary between the filters of each color, it is confirmed that the flatness is poor. It was done. And as a result of confirming the microlens formed on the color filter, the deformation | transformation which received the influence of the space | gap part of the corner | angular part of a color filter was seen.

[Comparative Example 4]
The color filters were formed in the same manner as in Comparative Example 3.
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 (0.5 μm) was formed. The thickness of the flattening layer is different from that of Example 1 in the height difference between the most convex portion of the formed flattening layer and the most concave portion corresponding to the boundary between filters of each color. The thickness was measured in the same manner, and was set as the thickness necessary to be the same as the surface roughness (height difference) of the color filter of Example 1 (0.22 μm).
Next, a microlens was formed on the planarization layer in the same manner as in 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 5.1 μm, which was thicker than that in Example 1.

[Comparative Example 5]
The photomask for the green filter uses the same photomask as in Example 1, and the photomask for the red filter and the photomask for the blue filter use a photomask without a sub-pattern to form a color filter. In the same manner as in Example 1, a solid-state image sensor was produced.
In manufacturing the solid-state imaging device, the color filter formed on the planarization layer was observed using an atomic force microscope, and as a result, it was confirmed that there were voids at the corners. Further, as in Example 1, the height difference between the most convex part of the color filter and the most concave part of the boundary between the filters of each color was measured, and as a result, it was 0.3 μm, It was confirmed that the flatness was poor. And as a result of confirming the microlens formed on the color filter, the deformation | transformation which received the influence of the space | gap part of the corner | angular part of a color filter was seen.

[Comparative Example 6]
The color filter was formed in the same manner as in Comparative Example 5.
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 is different from that of Example 1 in the height difference between the most convex portion of the formed flattening layer and the most concave portion corresponding to the boundary between filters of each color. The thickness was measured in the same manner, and was set as the thickness necessary to be the same as the surface roughness (height difference) of the color filter of Example 1 (0.22 μm).
Next, a microlens was formed on the planarization layer in the same manner as in 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 5.0 μm, which was thicker than that of Example 1.

[Comparative Example 7]
The color filter was formed in the same manner as in Comparative Example 1.
Next, as a microlens material, MFR401L manufactured by JSR Co., Ltd. is spin-coated (film thickness: 1.0 μm) so as to cover this color filter, and then a microlens is formed in the same manner as in Example 1 to form a solid. An image sensor was produced.
The coating thickness of the above-mentioned microlens material was set as a thickness necessary for a good lens without deformation as a result of observing the microlens formed on the color filter with an atomic force microscope.
In this solid-state imaging device, the microlens was a good lens with no deformation, but the height of the microlens was 0.9 μm, which was thicker than that of Example 1. In addition, the focal length of the microlens was thus as small as 2.7 μm compared to 4.6 μm in Example 1, and it was difficult to efficiently collect light on the photodiode (light receiving portion).

  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.

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 ... Micro lens array 21G ... Photomask for green filter 21R ... Photomask for red filter 22G, 22R ... Pattern 23 ... Notch 24 ... Subpattern 31, 41 ... Imaging device

Claims (1)

A planarizing layer; a color filter disposed on the planarizing layer; a microlens array comprising a plurality of microlenses disposed on the color filter; and the microlens below the planarizing layer. In a method for manufacturing a solid-state imaging device including a plurality of corresponding light receiving units,
The color filter is formed by applying a green filter photosensitive material on the planarization layer, exposing and developing using a green filter photomask, and forming a non-isolated rectangular green filter; Applying a photosensitive material for red filter, exposing and developing using a photomask for red filter to form an isolated rectangular red filter, applying a photosensitive material for blue filter, and blue And exposing and developing using a filter photomask to form an isolated rectangular blue filter,
The green filter photomask uses a photomask having a rectangular pattern with corners cut off,
The red filter photomask and the blue filter photomask use a photomask having a rectangular pattern having a sub-pattern at a corner ,
When the maximum distance from the intersection of the rectangular sides to the corner notch is the notch dimension, and the maximum length of the sub-pattern protruding outward from the corner is the sub-pattern dimension, the notch dimension And the sub-pattern dimension is a dimension that is not more than the resolution limit of the exposure apparatus under the mask exposure condition .

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