JP2011171328A - Solid-state image pickup element and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state image pickup element widely ensuring a normal film forming area free from quality failures such as frame color unevenness and peeling in a later color filter forming process regardless of a structure with a pixel part forming area surface formed lower than an upper surface of a multilayer wiring part in the solid-state image pickup element having a pixel part with a plurality of photoelectric conversion elements arranged on a plane, and the multilayer wiring part laminated and arranged around the pixel part. <P>SOLUTION: In the solid-state image pickup element, a step is formed in the vicinity of a boundary between both parts that a front surface of a light receiving plane of the pixel part area is positioned lower than the upper surface of the multilayer wiring part area, and a sloped transparent resin layer whose surface protrudes downward is provided on a surface ranging from the step to the pixel part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device having a photoelectric conversion device such as a CCD or CMOS, and a manufacturing method thereof.

  In recent years, imaging devices have been widely used with the expansion of the contents of image recording, communication, and broadcasting. Various types of image pickup devices have been proposed. An image pickup device incorporating a solid-state image pickup device that has been stably manufactured with a small size, light weight, and high performance can be used as a digital camera or digital video. It has become widespread.

  The solid-state imaging device has a plurality of photoelectric conversion elements that receive an optical image from a subject and convert incident light into an electrical signal. The types of photoelectric conversion elements are roughly classified into CCD (charge coupled device) type and CMOS (complementary metal oxide semiconductor) type. In addition, there are two types of photoelectric conversion elements: linear sensors (line sensors) in which photoelectric conversion elements are arranged in a row, and area sensors (surface sensors) in which photoelectric conversion elements are two-dimensionally arranged vertically and horizontally. It is divided roughly into. In any sensor, the larger the number of photoelectric conversion elements (number of pixels), the more accurate the captured image.

  In addition, by providing various color filters that transmit light of a specific wavelength in the path of light incident on the photoelectric conversion element, solid-state imaging as a single-plate color sensor that makes it possible to obtain color information of an object Elements are also widespread. As the color of the color filter, three primary colors consisting of three colors of red (R), blue (B), and green (G), or cyan (C), magenta (M), and yellow (Y) are used. Complementary color systems are generally used, and in particular, the three primary color systems are often used.

  The color filter is mainly formed using a photolithography method. That is, after applying a photosensitive colored resin of a predetermined color on a substrate, pattern exposure and development are performed on the photosensitive colored resin through an exposure photomask having a predetermined pattern, and the predetermined portion is made of a colored resin. A color filter is formed. In addition, spin coating is often used as the application of the photosensitive colored resin on the substrate. In other words, after the photosensitive colored resin is dropped on the substrate, the dropped photosensitive colored resin is spread on the substrate by rotating the substrate.

  One of the important issues in performance required for a solid-state imaging device is to improve the sensitivity to incident light. In order to increase the amount of information of an image photographed with a miniaturized solid-state imaging device, it is necessary to miniaturize and highly integrate a photoelectric conversion device serving as a light receiving unit. However, when the photoelectric conversion element is miniaturized, the area of each photoelectric conversion element is reduced, and the area ratio that can be used as the light receiving unit is also reduced. And the effective sensitivity decreases.

  As a means for preventing such a decrease in sensitivity of the miniaturized solid-state imaging device, in order to efficiently capture light into the light receiving portion of the photoelectric conversion device, the light incident from the object is condensed and photoelectrically A technique has been proposed in which a microlens that leads to a light receiving portion of a conversion element is formed on the photoelectric conversion element. By condensing the light with a microlens and guiding it to the light receiving part of the photoelectric conversion element, it becomes possible to increase the apparent aperture ratio (area) of the light receiving part and improve the sensitivity of the solid-state image sensor Become. In addition, a technique for further increasing sensitivity by shortening the distance between the microlens and the light receiving portion of the photoelectric conversion element and increasing the light capturing angle has been proposed (see Patent Document 1).

JP 2008-270500 A

  As described above, it is possible to increase the sensitivity by shortening the distance between the microlens and the light receiving portion of the photoelectric conversion element and increasing the light capturing angle. FIG. 2 is a partial cross-sectional schematic diagram for explaining the main part of a conventional solid-state imaging device formed up to the color filter 11 of the first color. The substrate 2 is dug in the upper part of the pixel portion A where the multilayer wiring is not provided, and the thickness of the pixel portion A of the substrate 2 is made thinner than the multilayer wiring portion B on the outer periphery thereof. Thereby, the distance between the photoelectric conversion element 3 and the microlens to be formed above the pixel portion A via the first color filter 11 and other color filters can be shortened. Here, in the multilayer wiring portion B, a plurality of wiring layers 4 are laminated and disposed via an interlayer insulating film 5 between the wiring layers. The color filter is also formed on the outer peripheral portion beyond the pixel portion A.

  However, since there is a step near the boundary between the surface of the pixel portion having a low surface position and the upper surface of the multilayer wiring portion having a high surface position, when the color filter is formed on the pixel portion prior to the formation of the microlens, As shown in FIG. 6, which is a simplified schematic partial sectional view, the thickness of the color filter layer in the vicinity of the step D tends to be partially thicker than the vicinity of the center of the pixel portion A. This is because a liquid pool is formed in the stepped portion C in the coating process of the colored resin 30 constituting the color filter. This tendency becomes prominent when a colored resin is applied by a spin coating method. In FIG. 2, a stepped portion C, which is a region where the thickness of the color filter layer in the vicinity of the step is partially thick, generates a region overlapping with the pixel portion A, and a portion where the color filter is formed with a uniform thickness is a stepped portion. The pixel portion A inside the portion C is limited to a portion near the center of the substrate far from the outer periphery of the substrate.

  The thickness of the color filter coloring layer formed in the vicinity of the stepped portion C that is the peripheral portion of the solid-state imaging device 1 is partially thicker than the central portion of the pixel portion A having a uniform thickness, thereby the vicinity of the stepped portion. The change in light transmittance between the color filter and the color filter in the center appears as unevenness, which causes “frame color unevenness” that results in poor quality of the solid-state imaging device 1. Further, in a general manufacturing method in which a color filter pattern is formed by a photolithographic method using a photo-curing type colored resin, a locally thick portion of the colored layer is a main exposure spectrum compared to other portions. Since the amount of transmitted light of i-line (wavelength 365 nm) decreases and the degree of curing becomes insufficient, and the stress inside the film also increases, the color filter pattern easily peels off at the stepped portion C including the portion immediately below the stepped portion. Further, by forming a locally thick portion of the colored layer as a solid film, peeling at the stepped portion C can be prevented, but the effective pixel region in which the color filter colored layer has a uniform thickness in the pixel portion A The problem of narrowing remains.

  The present invention is proposed in view of the above-mentioned problems, and the problem to be solved by the present invention is that a pixel portion in which a plurality of photoelectric conversion elements are arranged in a plane and a multilayer wiring portion in which a plurality of photoelectric conversion elements are laminated around the pixel portion. In the solid-state imaging device having the above, even if the area surface on which the pixel portion is formed is formed lower than the upper surface of the multilayer wiring portion, there is no quality defect such as uneven frame color or peeling in the subsequent color filter forming process It is an object of the present invention to provide a solid-state imaging device that ensures a wide normal film formation region.

As means for solving the above-mentioned problems, the invention according to claim 1 is a pixel unit region in which a plurality of photoelectric conversion elements are arranged in a plane, and a plurality of pixels electrically connected to the pixel unit on the outer periphery of the pixel unit region. In a solid-state imaging device having a multilayer wiring portion region in which wiring layers are laminated via an interlayer insulating film between each wiring layer, the light receiving surface of the pixel portion region is positioned lower than the upper surface of the multilayer wiring portion region A solid-state imaging device is characterized in that a step is formed in the vicinity of the boundary between the two portions, and a slope-shaped transparent resin layer having a convex downward surface is provided on the surface from the step to the pixel portion.

  According to a second aspect of the present invention, in the pixel region on the slope-shaped transparent resin layer, a color filter coloring layer, a planarizing layer, and a microlens are arranged in this order from the side closer to the light receiving surface of the photoelectric conversion element. The solid-state imaging device according to claim 1, wherein the solid-state imaging device is formed by stacking.

  According to a third aspect of the present invention, as a method of forming the slope-shaped transparent resin layer, a photosensitive surface side surface of a wafer device on which a plurality of solid-state imaging elements before forming the transparent resin layer is formed is photosensitive. The step of applying a transparent resin solution, the step of exposing using a photomask having a transmittance gradation, the step of developing with an alkaline solution, and the step of curing the resin by heat treatment are sequentially performed. This is a method for manufacturing a solid-state imaging device.

  According to a fourth aspect of the present invention, the photosensitive transparent resin liquid is a positive resist, and the transmittance of a photomask having a transmittance gradation has a minimum value at a position corresponding to immediately below the step. The solid-state imaging device manufacturing method according to claim 3, wherein the solid-state imaging device has an increasing tendency at a position corresponding to a region from the step portion to the pixel portion.

  The solid-state imaging device according to the present invention has a color filter coloring layer in advance in order to control the base cross-sectional shape of the step portion where the film thickness of the color filter tends to be partially increased due to the step between the pixel portion and the multilayer wiring portion. By providing a transparent resin layer with a controlled cross-sectional shape as the underlayer, even if the light receiving surface side surface of the pixel part is formed lower than the upper surface of the multilayer wiring part, quality defects such as frame color unevenness and peeling may occur. A normal film formation region of the color filter coloring layer that does not occur can be secured widely, and a solid-state imaging device of good quality can be provided. In addition, since a transparent resin layer having good adhesion to the color filter coloring layer can be formed as a uniform base of the pixel portion, it is possible to reduce general defects such as chipping of color filters and pinholes in the pixel portion. Has an effect.

It is a partial cross section schematic diagram for demonstrating the structure of the solid-state image sensor of this invention about the principal part in the middle of a process. It is a partial cross-sectional schematic diagram for demonstrating the structure of the conventional solid-state image sensor about the principal part in the middle of a process. BRIEF DESCRIPTION OF THE DRAWINGS In the manufacturing method of the solid-state image sensor of this invention, it is a schematic diagram for demonstrating the method of forming a slope-shaped transparent resin layer, Comprising: (a) is a partial cross-section schematic diagram in which the slope-shaped transparent resin layer was formed. (B) is a partial schematic plan view of a photomask used in an exposure process when forming a slope-shaped transparent resin layer, and (c) is a photomask of a portion corresponding to each part of the photomask in (b). An example of the light transmittance is shown. It is a partial cross-sectional schematic diagram for demonstrating an example of the solid-state image sensor of this invention. It is a partial plane schematic diagram for demonstrating an example of the plane arrangement | sequence of each color filter color in the solid-state image sensor of this invention. It is the simplified partial cross-section schematic diagram which shows the application | coating state of colored resin in the conventional application | coating process.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a partial cross-sectional schematic diagram for explaining the main part of the solid-state imaging device of the present invention during the process (when a first color filter among a plurality of color filters is formed).

  As shown in FIG. 1, a pixel portion A in which a plurality of photoelectric conversion elements 3 are arranged in a plane and a plurality of wiring layers 4 around the outer periphery of the pixel portion and electrically connected to the pixel portions are provided with interlayer insulation between the wiring layers. In the solid-state imaging device 1 having the multilayer wiring portion B laminated via the film 5, the surface of the region where the pixel portion A is formed is lower than the upper surface of the multilayer wiring portion, and near the boundary between both portions Are stepped.

  Since the upper portion of the pixel portion A where the multilayer wiring is not provided is dug to a depth of about 1 to 2 μm, the thickness of the substrate 2 in the region of the pixel portion A can be set as in the conventional solid-state imaging device. By making it thinner than the area of the surrounding multilayer wiring part B, the distance between the photoelectric conversion element 3 and the microlens to be formed thereon via the first color filter 11 and other color filters is shortened. it can.

  In the solid-state imaging device 1, the plurality of wiring layers 4 are disposed on a semiconductor substrate 2 having a pixel portion A in which the plurality of photoelectric conversion elements 3 are arranged in advance via an interlayer insulating film 5 between the wiring layers. A multilayer wiring portion B is formed in a stacked arrangement. This multilayer wiring portion forming step is a general method such as adding a processing means such as an etching method to a photolithography method or a printing method as well as a step forming step for forming a step near the boundary between the pixel portion and the multilayer wiring portion. The detailed description is omitted.

  A color filter colored layer is provided by sequentially arranging a plurality of color filters on the surface of the light receiving surface of the pixel portion A with colored pixels for each color, and prior to that, a transparent resin layer 6 is formed. Transparent resin layers should not be formed on connection terminals to obtain electrical connections from multilayer wiring or on scribe lines to separate individual chips from a wafer device on which a plurality of solid-state image sensors are collectively formed Although there are places, the transparent resin layer 6 is once and uniformly formed on the wafer device.

  The color filter 11 of the first color needs a certain film thickness in order to maintain desired color characteristics. However, when a color filter is suddenly formed on the light receiving surface side surface of the pixel portion A as in the prior art, As shown in FIG. 2 described above, since a liquid pool can be formed in the vicinity of the step portion in the step of applying the colored resin constituting the color filter, the region where the thickness of the color filter layer is larger than the desired thickness at the step portion C is wide. Thus, a portion where the color filter is formed to have a desired thickness and a uniform thickness is narrowly limited to a portion near the center of the substrate in the pixel portion A.

  On the other hand, in the present invention, prior to the formation of the color filter first color 11, the slope-shaped transparent resin layer 6 whose surface is convex downward is provided on the surface from the step to the pixel portion A. Thus, the degree of liquid pooling at the step portion in the colored resin application process can be reduced, and accordingly, the region where the thickness of the color filter layer at the step portion C is partially increased can be reduced. That is, the color filter of the pixel portion can be obtained in a normal desired uniform thickness in a wide area, and as a result, a solid-state imaging device with good quality with little frame color unevenness and peeling can be provided.

  FIG. 3 is a schematic diagram for explaining a method of forming a slope-shaped transparent resin layer in the method for manufacturing a solid-state imaging device of the present invention, and (a) shows a slope-shaped transparent resin layer formed. Partial cross-sectional schematic view, (b) is a schematic partial plan view of a photomask used in the exposure process when forming a slope-shaped transparent resin layer, and (c) is a portion corresponding to each part of the photomask in (b). An example of the light transmittance of the photomask is shown.

In the present invention, prior to the formation of the color filter, the transparent resin layer 6 is formed on the light receiving surface side. The transparent resin layer 6 is formed in a slope shape. As a method for forming the slope-shaped transparent resin layer, (1) a light receiving surface side surface of a wafer device on which a plurality of solid-state imaging elements before the transparent resin layer is formed is formed. A step of applying a photosensitive transparent resin solution to the substrate, (2) a step of exposing using a photomask having the above-described transmittance gradation, (3) a step of developing with an alkali solution, and a step of curing the resin by heat treatment. Is.

  In forming the transparent resin layer 6, the photosensitive transparent resin liquid is a positive resist, the transmittance of the photomask having a transmittance gradation has a minimum value at a position corresponding to the level immediately below the level difference, and the level difference It is preferable to have an increasing tendency at a position corresponding to a region from the portion to the pixel portion.

  The transparent resin layer 6 forms a downward sloped cross-sectional shape on the surface mainly including the stepped portion C from the stepped portion to the pixel portion A, and the surfaces of the pixel portion A and the multilayer wiring portion B are flattened. Also has a role to make. However, when the transparent resin layer 6 is simply formed thick and the distance between the photoelectric conversion element 3 of the light receiving portion and the microlens 8 of the light receiving portion is increased to fill the stepped portion C, the microlens and the light receiving portion are received. This is not desirable because the distance to the part increases and the direction is in conflict with the increase in sensitivity of the solid-state imaging device. As the transparent resin layer 6, for example, a colorless and transparent acrylic resin solution is formed thinly on the pixel portion A and the multilayer wiring portion B, and on the stepped portion C, the surface has a slope-like cross-sectional shape that protrudes downward. The film can be formed by a method of changing the thickness of the film, and then cured by heat treatment.

  As described above, as a method of forming a slope-shaped cross-sectional shape with a convex surface downward with a transparent resin, a photolithography method using a photosensitive transparent resin liquid is used to form a transmittance gradation on a photomask for exposure. A so-called gray mask of a gray tone mask or a half tone mask having an intermediate density region provided with a so-called gray mask can be used.

  That is, as a method of creating an intermediate density region on a photomask, a semi-transparent layer is obtained as an average of the entire fine pattern region by a collection of fine patterns of a light shielding film such as dot (halftone dot) arrangement and line and space. There are a general gray-tone mask type that forms a light part and a half-tone mask type that forms a semi-transparent part by directly forming a semi-transparent film and patterning means. The former gray-tone mask type, in which only one type of light-shielding film needs to be vacuum-deposited, is the latter, which requires vacuum film-forming to be carried out in at least two types of light-shielding film material and semi-transmissive film material. However, the manufacturing process is simpler. However, due to the diffraction interference effect of light at the periphery of the pattern, the gray-tone mask type has large variations in light intensity, and it may be difficult to maintain good shape quality especially in areas where the film thickness is large. It is necessary to select an appropriate type according to the shape of the slope that is desired.

  The transparent substrate of the photomask transmits at least the wavelength of the region utilizing the photosensitivity of the photosensitive resin used in the resist exposure light from the exposure machine. Glass etc. are mentioned. Also, in the manufacture of photomasks, the light-shielding portion is formed by patterning a metal chromium film that has been mainly formed by a sputtering method or a low-reflection film in which chromium oxide is laminated on metal chromium by a photo-etching method. However, the etching means may be a wet method or a dry method. Further, the gray tone portion can be formed of the same material as the light shielding portion, and can be formed by a device on the pattern such as a slit in the same process as the light shielding portion formation.

  Further, it is appropriate to use a chromium oxide translucent film for the halftone portion, and it is desirable that the spectral transmittance be as flat as possible in the vicinity of the visible range, and a desired transmittance can be obtained by controlling the film thickness. be able to. Chromium oxide as a thin film material is generally formed by a sputtering method, and its absorption coefficient varies depending on the degree of oxidation, but it may be optimized from the etching suitability and the required film thickness in later patterning. The halftone part can be patterned by the same means as the patterning of the light shielding part. In addition, although a semi-transparent film is used in the same way as the halftone mask, another method of patterning the semi-transparent portion with an arbitrary transmittance by controlling the etching amount of the film formed with a constant film thickness is also possible. It is.

  In a photomask used in an exposure process when forming a slope-shaped transparent resin layer with a positive resist, shown in a partial plan view in FIG. 3B, for example, a mask region 20 corresponding to the multilayer wiring portion B, An example of the light transmittance T (%) of the mask in each of the mask regions 21, 22, 23 corresponding to the stepped portion C and the mask region 24 corresponding to the pixel portion A is shown in (c).

  In the mask region 20 corresponding to the multilayer wiring portion B and the mask region 24 corresponding to the pixel portion A, T is as high as 80%, and when a positive resist is used as the material of the transparent resin layer, the transparent region in this region is transparent. Most of the resin is dissolved and removed by development after exposure, leaving a slight thickness of about 0.1 μm. On the other hand, of the mask regions corresponding to the stepped portion C, T is as low as 30% in the region 21 directly below the step, and T is 50% in the regions 22 and 23 corresponding to the positions approaching the pixel portion. 70%, the film thickness of the transparent resin in the corresponding region shows a maximum residual ratio immediately below the step, and the film thickness residual ratio decreases toward the pixel portion. Since the coating thickness of the transparent resin at the stepped portion has a certain slope that decreases toward the pixel portion, the cross-sectional shape of the transparent resin layer 6 is applied when the reduction in the residual ratio of the transparent resin due to exposure and development as described above is added. Can be formed into a slope that is convex downward, and the descending angle of the slope can be rapidly reduced.

FIG. 4 is a partial cross-sectional schematic diagram for explaining an example of the solid-state imaging device of the present invention.
The color filter coloring layers 11, 12, the flattening layer 7, and the microlens 8 are stacked in this order from the side close to the light receiving surface of the photoelectric conversion element 3 in the pixel portion region where the transparent transparent resin layer 6 extends. By doing so, a highly sensitive color solid-state imaging device can be obtained.

  As the color filter 11 of the first color, for example, a photosensitive negative resist that is a green pigment dispersion resin is applied. Here, since the influence of the stepped portion C is limited to a sufficiently narrow region, the pixel film thickness on the pixel portion A becomes uniform, and a region where a color filter having a desired film thickness can be formed is wide. Become. After applying the resist, the first color filter 11 is patterned to a thickness of, for example, 0.9 μm through prebaking, selective exposure, development, and heat treatment. In the selective exposure, alignment with the photoelectric conversion element 3 provided below is important, and governs the quality of the miniaturized solid-state imaging element.

  Next, the remaining color layers including the second color filter and the subsequent colors are formed. A photosensitive negative resist, which is a pigment-dispersed resin of a selected color, is applied and formed through prebaking, selective exposure, development, and heat treatment steps as described above. As will be described later, since it is preferable to make the pixel film thickness thinner for the second and subsequent colors than for the first color, the material and content ratio of the pigment and the prescription as a dispersion resin in consideration of the required color characteristics. Is appropriately selected.

  This completes the color filter forming step of sequentially arranging a plurality of color filters on the surface of the light receiving surface of the pixel portion by color, and then the microlens 8 is mounted via the planarizing layer 7 provided on each color filter color. A microlens forming step for planar arrangement is performed.

The flattening layer 7 covers the uneven thickness of each color of the color filter in the pixel portion A and minute unevenness, and provides a flat and uniform base for forming a microlens. A resin solution is applied and formed to a thickness of 0.2 μm and heat-treated.
After the planarization layer 7 is formed, a photosensitive positive resist, which is a transparent resin as a lens material, is applied and formed on the planarization layer, prebaked, selectively exposed, developed with an organic alkali developing aqueous solution, and a heat treatment step is performed. In addition, by utilizing the thermal reflow behavior, a microlens 8 arranged in a plane by repeating the same unit is made a microlens having a convex lens shape with a height of 0.5 μm so as to coincide with the pixel pitch in the upper region of the pixel portion A. A plurality of lines are aligned.

Finally, the solid-state imaging device is completed through a connection terminal portion forming step and a step for cutting and separating a large number of solid-state imaging devices on the wafer device and mounting each chip.

  An example of the color filter planar arrangement will be described with reference to FIG. It is an example of a Bayer array of color filter pixels suitable for performing single-plate color imaging with a single solid-state imaging device. In accordance with human visibility, the number of colored pixels of the green colored layer 31 is larger than the number of colored pixels of the blue colored layer 32 and the red colored layer 33.

  In the example of the Bayer arrangement, it is desirable that the green coloring layer 31 is the color filter first color 11 and the blue coloring layer 32 and the red coloring layer 33 are formed after the second color. This is because the area occupied by the green colored layer 31 is relatively large, and the adhesion is further enhanced by connecting to the colored pixels of the same color located on the diagonal.

  In general, it is desirable to make the pixel film thickness of the second and subsequent colors of the color filter in the effective area of the pixel portion thinner than the pixel film thickness of the first color. By doing so, the color filter second color and the third color have a pixel film thickness that is thinner than the first color even in the stepped portion C, and the thin pixel film in the form in which the first color sinks into the already-patterned missing part. Thickness is formed, and the adverse effect of the step portion is reduced. Accordingly, the frame color unevenness and peeling in the second and third color filter colors do not matter. Further, in the area of the pixel portion A, when the first color is green in the Bayer array, each pixel of the color filter second color and third color is formed with four sides surrounded by a high wall of the first color. Therefore, it is difficult for defects such as peeling to occur.

Examples of the solid-state imaging device of the present invention will be described below.
<Example 1>
[Process]
A photosensitive positive transparent resin solution is spin-coated at a thickness of 1 μm (rotary coating) on a semiconductor device in which an area where a large number of light receiving elements made of photoelectric conversion elements are arranged is dug by about 1 μm with respect to the upper surface of the chip. Method) and prebaking at 90 ° C. for 90 seconds.
Next, the transparent resin film was exposed using a photomask having a transmittance gradation. In the transmittance gradation, the transmittance near the step is low, and the transmittance is increased toward the pixel portion. Further, the transmittance of the photomask corresponding to the portion where the transparent resin film such as the scribe line should be removed is set to 100%, and the transmittance on the external electrode such as the connection terminal portion is set to 0% so that the transparent resin film is left as a protective film. I made it. Subsequently, it developed and heat-processed and the transparent resin layer in which the slope-like pattern in which the surface protruded below was formed in the level | step-difference part was formed. The thickness of the transparent resin layer in the pixel portion where a large number of light receiving elements are arranged was 0.1 μm.
Next, a green negative color resist (pigment dispersion type) is spin-coated and pre-baked (70 ° C., 1 minute) on the green colored layer, which is the first color of the color filter, and selectively exposed, developed, and heat-treated to form a green pixel. The pattern was formed to a thickness of 0.9 μm.
Subsequently, the blue and red colored layers were also formed in a predetermined arrangement by a photolithography method in the same manner as the green colored layer. The pixel thicknesses of the blue and red colored layers were thinner than the pixel thickness of the green colored layer, and were 0.7 μm and 0.8 μm, respectively.
Next, an acrylic resin solution was applied and formed on the surface of the color filter pattern with a thickness of 0.2 μm by a spin coating method, followed by heat treatment.
Next, a positive resist to be a lens was applied and formed, and after prebaking, selectively exposed. Thereafter, development was performed with an organic alkali developing aqueous solution (TMAH system: 0.5%), and a micro lens having a height of 0.5 μm was formed by a thermal reflow method.
Next, a transparent resin is applied and formed in a thickness of 3 μm as a positive resist, pre-baked at 100 ° C. for 120 seconds, and then selectively exposed to portions such as connection terminal portions and scribe lines where the transparent resin is to be removed. Then, it developed with organic alkali developing aqueous solution (TMAH type | system | group: 0.5%).
Next, using the positive resist pattern as an etching mask, the resin under the opening was etched away by dry etching. The dry etching is performed using an ULVAC NA1300 output of 500 W, a gas pressure of 50 Pa, and an O ₂ flow rate of 600 cm ³ / min. (1 hPa, 0 ° C.), N ₂ flow rate 10 cm ³ / min. (1 hPa, 0 ° C.), etching rate 0.5 μm / min. And then removed by 1 μm etching.
Next, about 2 μm thickness of the positive resist remaining without being dry-etched was stripped and removed with a stripping solution.
Finally, heat treatment was performed at 100 ° C. for 2 minutes in order to remove moisture.
[Evaluation]
The obtained solid-state image pickup device was a high-quality color solid-state image pickup device with almost no frame color unevenness and no color peeling of the color filter coloring layer in the vicinity of the wafer level difference.
Further, the pixel sensitivity of each color of green, blue, and red is good and uniform in the chip, and is a high-quality color solid-state imaging device.

A comparative example of the solid-state imaging device of the present invention will be described below.
<Comparative example 1>
[Process]
An acrylic resin solution is applied in a thickness of 0.1 μm to an area where light receiving elements on a semiconductor device in which a large number of light receiving elements made of photoelectric conversion elements are arranged is dug by about 1 μm with respect to the upper surface of the chip And heat treatment.
Next, a green negative color resist (pigment dispersion type) is spin-coated and pre-baked (70 ° C., 1 minute) on the green colored layer, which is the first color of the color filter, and selectively exposed, developed, and heat-treated to form a green pixel. The pattern was formed to a thickness of 0.9 μm.
Subsequently, the blue and red colored layers were also formed in a predetermined arrangement by a photolithography method in the same manner as the green colored layer. At this time, the blue and red pixel thicknesses were made larger than the green pixel thickness.
Hereinafter, it was formed in the same manner as in Example 1 and was designated as Comparative Example 1.
[Evaluation]
In the obtained solid-state imaging device, frame color unevenness occurred in the vicinity of the stepped portion. For a step difference of 1 μm in height difference, the flat range of the frame color unevenness extends from the step to about 30 μm. In addition, the green pixels near the step were peeled off and the shape was distorted.
Further, the blue and red pixel thicknesses were also affected by the thickness of the step as in the case of the green color, and pixel peeling occurred for blue.
Further, the pixel sensitivity of each color of green, blue, and red was also inferior in uniformity within the chip.

DESCRIPTION OF SYMBOLS 1 ... Solid-state image sensor 2 ... Board | substrate 3 ... Photoelectric conversion element 4 ... Wiring layer 5 ... Interlayer insulation film 6 ... Transparent resin layer 7 ... Flattening layer 8 ... Micro lens 11 ... first color filter 12 ... second color filter 20 ... corresponding to mask areas 21, 22, 23 ... on stepped portion C on multilayer wiring part B Mask area 24 to be applied ... Mask area 30 corresponding to the pixel part A ... Colored resin 31 ... Green colored layer 32 ... Blue colored layer 33 ... Red colored layer A ... Pixel part B ... multilayer wiring part C ... step part D ... step

Claims (4)

  A multi-layer wiring unit in which a plurality of photoelectric conversion elements are arranged in a plane, and a plurality of wiring layers that are electrically connected to the pixel unit on the outer periphery of the pixel unit region are stacked via an interlayer insulating film between each wiring layer A step is formed in the vicinity of the boundary between the two parts so that the light receiving surface of the pixel part region is lower than the upper surface of the multilayer wiring part region, and on the surface from the step to the pixel part. And a slope-shaped transparent resin layer having a convex downward surface.   2. A color filter coloring layer, a flattening layer, and a microlens are laminated and formed in this order from a side close to a light receiving surface of a photoelectric conversion element in a pixel portion region on the slope-shaped transparent resin layer. The solid-state image sensor described in 1.   As a method for forming the slope-shaped transparent resin layer, a step of applying a photosensitive transparent resin liquid to a light-receiving surface side surface of a wafer device on which a plurality of solid-state imaging elements before forming the transparent resin layer is formed; The method for producing a solid-state imaging device according to claim 1, wherein a step of exposing using a photomask having a tone, a step of developing with an alkaline solution, and a resin curing step by heat treatment are sequentially performed.   The photosensitive transparent resin liquid is a positive resist, the transmittance of a photomask having a transmittance gradation has a minimum value at a position corresponding to the level immediately below the step, and the region from the step to the pixel portion The method for manufacturing a solid-state imaging device according to claim 3, wherein the solid image pickup device has an increasing tendency at a position corresponding to.