JP2010245129A - Solid-state image sensor - Google Patents

Abstract

A solid-state imaging device capable of improving light collection efficiency without deteriorating color reproducibility.
A solid-state imaging device 50 according to the present invention is included in each pixel, and includes a plurality of light receiving portions 2 formed on a semiconductor substrate 1 and a color filter 4 formed on the plurality of light receiving portions 2. A grid pattern 6 formed on the color filter 4 so as to cover the boundaries of the pixels, and the color filter 4 and the grid pattern 6. A formed acrylic film 7 and a plurality of on-chip microlenses 8 formed on the acrylic film 7 are provided. The upper surface of the acrylic film 7 has a downward convex shape, the upper surfaces of the plurality of on-chip microlenses 8 have an upward convex shape, and the lower surface has a downward convex shape.
[Selection] Figure 1

Description

  The present invention relates to a solid-state imaging device, and more particularly to a solid-state imaging device including an on-chip microlens.

  Currently, solid-state imaging devices are widely used as image input units for digital still cameras or mobile phones. With the progress of the increase in the number of pixels of the solid-state imaging device, the pixel size has been miniaturized. In addition, with the miniaturization of the pixel size, the light receiving portion is miniaturized. As a result, there is a problem that deterioration of characteristics of the solid-state imaging device such as sensitivity reduction occurs.

  In order to increase the light collection efficiency at the light receiving unit of the solid-state imaging device, various combinations of shapes of on-chip microlenses and in-layer lenses have been proposed. For example, in the solid-state imaging device described in Patent Document 1, the shape of the on-chip microlens is optimized in order to increase the light collection efficiency of the light receiving unit.

  Hereinafter, the structure of the conventional solid-state imaging device 100 will be described with reference to FIGS. 9 and 10. 9 and 10 are cross-sectional views showing the structure of a conventional solid-state imaging device 100. FIG. FIG. 9 shows the propagation direction of the light beam when the light beam is perpendicularly incident on the light receiving unit. FIG. 10 shows the propagation direction of the light beam when the light beam is incident on the light receiving unit obliquely.

  9 and 10 includes a semiconductor substrate 101, a light receiving unit 102, an insulating film 103, a pattern 104, a color filter 105, a planarizing film 106, and an on-chip microlens 107. Prepare.

  Hereinafter, a method for manufacturing the solid-state imaging device 100 will be described.

  First, the oxide insulating film 103 is deposited on the semiconductor substrate 101 having the light receiving portion 102. Next, a pattern 104 having a predetermined height is formed around the color filter 105. Next, after the filter material is coated to a predetermined thickness, the color filter 105 is formed by patterning. Here, each of the formed color filters 105 has a concave upper surface as a result of the pattern 104 being formed in the periphery of the light receiving unit 102. Next, a planarization film 106 is formed on the color filter 105, and an on-chip microlens 107 is formed thereon.

  With the above configuration, the light beam incident through the on-chip microlens 107 and the planarizing film 106 whose lower surface is convex is refracted in the center direction of the pixel. As a result, the conventional solid-state imaging device 100 can efficiently guide the light beam incident on the periphery of the on-chip microlens 107 to the light receiving unit 102.

JP-A-10-174003

  However, the conventional solid-state imaging device 100 has the following problems. In the conventional solid-state imaging device 100, when the diameter of the downward convex shape (the length in the horizontal direction or the depth direction in FIGS. 9 and 10) of the boundary surface between the planarization film 106 and the color filter 105 is increased, it enters the adjacent pixel. Color mixing occurs when light leaks. Thereby, color reproducibility deteriorates. For this reason, the conventional solid-state imaging device 100 cannot form a downwardly convex shape having a large curvature.

  Moreover, in the conventional solid-state imaging device 100, since the diameter of the downward convex shape of the boundary surface between the planarizing film 106 and the color filter 105 is small, the flow property of the on-chip microlens 107 formed thereon cannot be suppressed. . Thereby, the on-chip microlens 107 having a low curvature is formed. For this reason, the conventional solid-state image sensor 100 cannot expect a high condensing effect.

  In view of the above problems, an object of the present invention is to provide a solid-state imaging device that can improve light collection efficiency without deteriorating color reproducibility.

  In order to solve the above-described problems, a solid-state imaging device according to the present invention is a solid-state imaging device having a plurality of pixels arranged in a matrix, and is included in each of the pixels and the semiconductor substrate. A photoelectric conversion unit that converts incident light into an electrical signal, a color filter formed above the plurality of photoelectric conversion units, and an opening above each of the plurality of photoelectric conversion units, and A grid pattern formed on the color filter so as to cover the boundary of the pixels, a transparent film formed on the color filter and the grid pattern, and the transparent film included in each pixel An on-chip microlens formed thereon, and an upper surface of the transparent film in contact with each on-chip microlens has a downwardly convex shape, and the plurality of on-chip microlenses The upper surface is upward convex shape, the lower surface is a downwardly convex shape.

  According to this configuration, in the solid-state imaging device according to the present invention, the downward convex curvature of the on-chip microlens is formed in a desired size by arbitrarily selecting the height and width of the lattice pattern. Is possible. Furthermore, the lattice pattern acts as a wall that separates the on-chip microlenses of adjacent pixels. Thereby, since the on-chip microlens of an adjacent pixel does not contact, it becomes possible to suppress the heat flow property of the on-chip microlens. Thereby, the curvature of the upward convex shape of the on-chip microlens can be increased.

  Thus, the solid-state imaging device according to the present invention can increase the curvature of the biconvex on-chip microlens without increasing the diameter of the on-chip microlens. In other words, the solid-state imaging device according to the present invention can prevent color mixing due to incident light leaking into adjacent pixels, thereby preventing deterioration in color reproducibility. Furthermore, by forming a biconvex on-chip microlens having a large curvature, the solid-state imaging device according to the present invention can realize high light collection efficiency.

  Moreover, the refractive index of the lattice pattern may be smaller than the refractive index of the transparent film.

  According to this configuration, since the oblique incident light is reflected by the lattice pattern, the solid-state imaging device according to the present invention can prevent the incident light from entering the adjacent pixels. Therefore, since the solid-state imaging device according to the present invention can prevent color mixture from occurring, it can prevent deterioration of color reproducibility.

  The lattice pattern may absorb light.

  According to this configuration, since the oblique incident light is absorbed by the lattice pattern, the solid-state imaging device according to the present invention can prevent the incident light from entering the adjacent pixels. Therefore, since the solid-state imaging device according to the present invention can prevent color mixture from occurring, it can prevent deterioration of color reproducibility.

  The cross-sectional shape of the lattice pattern may be square or rectangular.

  The cross-sectional shape of the lattice pattern may be a triangle.

  The cross-sectional shape of the lattice pattern may be a trapezoid.

  The upper surface of the color filter may be flat.

  The solid-state imaging device may further include a first transparent flattening film formed between the color filter and the transparent film.

  According to this configuration, since the surface on which the lattice pattern is formed can be flattened, the lattice pattern can be generated with high accuracy.

  Further, each of the plurality of on-chip microlenses may be formed independently.

  According to this configuration, since it is possible to suppress the heat flow property of the on-chip microlens, it is possible to increase the curvature of the upward convex shape of the on-chip microlens.

  The refractive index of the on-chip microlens may be higher than the refractive index of the transparent film.

  A second transparent planarizing film formed on the on-chip microlens; and a transparent plate formed on the second transparent planarizing film, the second transparent planarizing film comprising an organic adhesive material The transparent plate and the on-chip microlens may be bonded together.

  According to this configuration, the on-chip microlens and the transparent plate can be easily connected using the organic adhesive material.

  In addition, this invention is realizable as a manufacturing method of the solid-state image sensor which manufactures such a solid-state image sensor.

  Furthermore, the present invention can be realized as a semiconductor integrated circuit (LSI) including part or all of the functions of such a solid-state image sensor, or can be realized as a camera including such a solid-state image sensor.

  As described above, it is possible to provide a solid-state imaging device capable of improving the light collection efficiency without deteriorating the color reproducibility.

It is sectional drawing which shows the structure of the solid-state image sensor which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the structure in the manufacture process of the solid-state image sensor which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the structure in the manufacture process of the solid-state image sensor which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the structure in the manufacture process of the solid-state image sensor which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the structure in the manufacture process of the solid-state image sensor which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the structure in the manufacture process of the solid-state image sensor which concerns on Embodiment 1 of this invention. In the solid-state imaging device according to Embodiment 1 of the present invention, it is a diagram illustrating a propagation direction of a light beam when the light beam is perpendicularly incident on a light receiving unit. In the solid-state imaging device according to Embodiment 1 of the present invention, it is a diagram illustrating a propagation direction of a light beam when the light beam is incident on the light receiving unit from an oblique direction. It is sectional drawing which shows the structure of the solid-state image sensor which concerns on Embodiment 2 of this invention. It is sectional drawing which shows the structure of the solid-state image sensor which concerns on Embodiment 3 of this invention. It is sectional drawing which shows the structure of the solid-state image sensor which concerns on Embodiment 4 of this invention. It is sectional drawing which shows the structure of the solid-state image sensor which concerns on Embodiment 5 of this invention. It is a figure which shows the propagation direction of a light beam when a light beam injects into a light-receiving part perpendicular | vertical in the conventional solid-state image sensor. In the conventional solid-state image sensor, it is a figure which shows the propagation direction of a light beam when a light beam injects into the light-receiving part from diagonally.

  The best mode for carrying out the present invention will be described below with reference to the drawings. The drawings of each embodiment used in the following description are shown as an example in order to easily understand the configuration of the solid-state imaging device according to the present invention, and the operation and effect thereof. The portions other than the gist are not limited to these.

(Embodiment 1)
The solid-state imaging device according to the first embodiment of the present invention includes a lattice pattern that covers pixel boundaries on a color filter. Furthermore, the solid-state imaging device according to the first embodiment of the present invention uses this lattice pattern to form an acrylic film having an upwardly convex upper surface on the lattice pattern, and biconvex on the acrylic film. On-chip microlenses are formed. Thereby, the solid-state imaging device according to Embodiment 1 of the present invention can form a biconvex on-chip microlens having a large curvature without deteriorating the color reproducibility.

  First, the structure of the solid-state imaging device 50 according to Embodiment 1 of the present invention will be described.

  The solid-state imaging device 100 according to Embodiment 1 of the present invention is, for example, a CCD image sensor, a MOS image sensor, or a CMOS image sensor. This solid-state imaging device 100 has a plurality of pixels arranged in a matrix on a two-dimensional plane.

  FIG. 1 is a cross-sectional view showing the structure of one pixel of a solid-state imaging device 50 according to Embodiment 1 of the present invention. 1 includes a semiconductor substrate 1, a light receiving unit 2, an insulating film 3, a color filter 4, an acrylic flattening film 5, a lattice pattern 6, an acrylic film 7, and a biconvex on. Chip microlens 8. The light receiving unit 2, the color filter 4, and the biconvex on-chip microlens 8 are included in each pixel.

  The light receiving unit 2 is a photoelectric conversion unit that is formed on the semiconductor substrate 1 and converts incident light into an electrical signal.

  The insulating film 3 is formed on the semiconductor substrate 1. For example, the insulating film 3 is an oxide insulating film.

  The color filter 4 is formed on the insulating film 3 above the light receiving unit 2 and transmits light in a predetermined wavelength band. Further, the upper surface of the color filter 4 is flat.

  The acrylic planarizing film 5 is formed on the color filter 4 and transmits visible light.

  The grid pattern 6 is formed on the acrylic planarizing film 5. In addition, the grid pattern 6 has a grid shape that has an opening above the light receiving unit 2 of each pixel and covers the boundary of the pixel when viewed from the upper surface (upward direction in FIG. 1). The grid pattern 6 has a square or rectangular cross-sectional shape.

  The acrylic film 7 is formed on the acrylic flattening film 5 and the grid pattern 6 so as to cover the acrylic flattening film 5 and the grid pattern 6. The upper surface of the acrylic film 7 has a downwardly convex shape with the center of the pixel as the center. The acrylic film 7 transmits visible light.

  The on-chip microlens 8 is formed on the acrylic film 7 in a downward convex shape of the acrylic film 7. The upper surface of the on-chip microlens 8 has an upward convex shape, and the lower surface has a downward convex shape along the downward convex shape of the acrylic film 7. Moreover, the on-chip microlenses 8 of each pixel are formed independently.

  With the above configuration, when the acrylic film 7 under the on-chip microlens 8 is formed, the curvature of the upper surface of the acrylic film 7 having a downward convex shape can be selected by arbitrarily selecting the height and width of the lattice pattern 6. Can be determined.

  The refractive index of the lattice pattern 6 is smaller than the refractive index of the acrylic film 7. Thereby, since the oblique incident light is reflected by the lattice pattern 6, it is possible to prevent the incident light from entering the adjacent pixels. Therefore, since the solid-state imaging device 50 can prevent color mixture from occurring, it can prevent deterioration in color reproducibility.

  Alternatively, the lattice pattern 6 may be formed of a light absorbing material that absorbs light. Thereby, since the oblique incident light is absorbed by the lattice pattern 6, it is possible to prevent the incident light from entering the adjacent pixels. Therefore, since the solid-state imaging device 50 can prevent color mixture from occurring, it can prevent deterioration in color reproducibility.

  In addition, the refractive index of the biconvex on-chip microlens 8 is higher than that of the acrylic film 7.

  Next, a method for manufacturing the solid-state imaging element 50 according to Embodiment 1 of the present invention will be described with reference to FIGS. 2A to 2E. 2A to 2E are cross-sectional views showing the structure of the solid-state imaging device 50 in the manufacturing process.

  First, the light receiving portion 2 is formed in the semiconductor substrate 1 by performing ion implantation or the like. Next, the insulating film 3 is laminated on the semiconductor substrate 1 on which the light receiving portion 2 is formed (FIG. 2A).

  Next, the color filter 4 is formed on the insulating film 3 by performing spin coating and patterning using a photomask (FIG. 2B).

  Next, planarization on the color filter 4 is performed by forming the acrylic planarization film 5 on the color filter 4 using spin coating (FIG. 2C).

  Next, after a synthetic resin film is spin-coated on the acrylic flattening film 5, patterning using a photomask is performed to form a lattice pattern 6 in the periphery of each pixel (FIG. 2D). Here, the lattice pattern 6 has a height of 0.1 μm to 5.0 μm and a width of 0.1 μm to 5.0 μm. The shape of the cross section of the grid pattern 6 is a square or a rectangle, and the height and width of the grid pattern 6 are selected so as to form an on-chip microlens 8 having a desired curvature.

  Next, an acrylic film 7 is spin-coated on the grid pattern 6. At this time, by using the unevenness determined by the height and width of the grid pattern 6, an acrylic film 7 having a downward protrusion is formed at the center of the pixel (FIG. 2E).

  Next, after a synthetic resin film is spin-coated on the acrylic film 7, a separate and independent resist pattern is formed on each pixel using a photomask. Next, a biconvex on-chip microlens 8 having curved surfaces up and down is formed by heat-flowing the formed resist pattern (FIG. 1). At this time, a plurality of on-chip microlenses 8 are formed so that the on-chip microlenses 8 of adjacent pixels do not contact each other.

  As described above, in the solid-state imaging device 50 according to Embodiment 1 of the present invention, the curvature of the downward convex shape of the on-chip microlens 8 is set to a desired size by arbitrarily selecting the height and width of the lattice pattern 6. Can be formed.

  Further, the grid pattern 6 functions as a wall that separates the on-chip microlenses 8 of adjacent pixels. Thereby, since the on-chip microlens 8 of the adjacent pixel does not contact, it becomes possible to suppress the heat flow property of the on-chip microlens 8. Therefore, the upward convex curvature of the on-chip microlens 8 can be formed high.

  As a result, the solid-state imaging device 50 can increase the curvature of the biconvex on-chip microlens 8 without increasing the diameter of the on-chip microlens 8 (the length in the horizontal direction or the depth direction in FIG. 1). . That is, the solid-state imaging device 50 can prevent color mixture from occurring due to leakage of incident light to adjacent pixels, thereby preventing deterioration in color reproducibility.

  3 and 4 are cross-sectional views showing the structure of the solid-state imaging device 50 according to Embodiment 1 of the present invention. FIG. 3 shows the propagation direction of the light beam when the light beam is perpendicularly incident on the light receiving unit 2. FIG. 4 shows the propagation direction of the light beam when the light beam is incident on the light receiving unit 2 from an oblique direction.

  As shown in FIGS. 3 and 4, by forming the biconvex on-chip microlens 8 having a large curvature, the solid-state imaging device 50 efficiently receives the light beam incident on the peripheral portion of the on-chip microlens 8. Part 2 can be guided. Therefore, the solid-state imaging device 50 can realize high light collection efficiency.

(Embodiment 2)
A solid-state image sensor 51 according to the second embodiment of the present invention is a modification of the solid-state image sensor 50 according to the first embodiment, and includes a grid pattern 16 having a triangular cross section.

  First, the structure of the solid-state image sensor 51 according to Embodiment 2 of the present invention will be described.

  FIG. 5 is a cross-sectional view showing the structure of the solid-state imaging device 51 according to Embodiment 2 of the present invention. Here, for ease of explanation, the same components as those of the solid-state imaging device 50 according to Embodiment 1 are denoted by the same reference numerals, and redundant description is omitted.

  A solid-state imaging device 51 illustrated in FIG. 5 includes a lattice-shaped pattern 16 instead of the lattice-shaped pattern 6 with respect to the solid-state imaging device 50 illustrated in FIG.

  The grid pattern 16 has a grid shape that has openings above the light receiving portions 2 of the respective pixels and covers the boundaries of the pixels when viewed from the upper surface (upward direction in FIG. 5). The grid pattern 16 has a triangular cross-sectional shape in which one side is in contact with the upper surface of the acrylic planarizing film 5. Then, when the acrylic film 7 under the on-chip microlens 8 is formed, the curvature of the upper surface of the acrylic film 7 that is downwardly convex can be determined by arbitrarily selecting the height and width.

  Next, a method for manufacturing the solid-state imaging device 51 according to Embodiment 2 of the present invention will be briefly described.

  First, the light receiving portion 2 is formed in the semiconductor substrate 1 by performing ion implantation or the like. Next, the insulating film 3 is laminated on the semiconductor substrate 1 on which the light receiving unit 2 is formed.

  Next, the color filter 4 is formed on the insulating film 3 by performing spin coating and patterning using a photomask. Next, the flattening on the color filter 4 is performed by forming the acrylic flattening film 5 on the color filter 4 using spin coating. Next, after a synthetic resin film is spin-coated on the acrylic flattening film 5, patterning using a photomask is performed to form a lattice pattern 16 in the periphery of each pixel. Here, the height of the grid pattern 16 is 0.1 μm to 5.0 μm, the width of the base of the triangular triangle is 0.1 μm to 5.0 μm, and the on-chip microlens 8 having a desired curvature is formed. Thus, the height and width of the lattice pattern 16 are selected.

  Next, the acrylic film 7 is spin-coated on the lattice pattern 16. At this time, by using the unevenness determined by the height and width of the lattice pattern 16, the acrylic film 7 that forms a downward protrusion is formed at the center of the pixel. Next, after a synthetic resin film is spin-coated on the acrylic film 7, a separate and independent resist pattern is formed on each pixel using a photomask. Next, the formed resist pattern is heat-flowed to form a biconvex on-chip microlens 8 having curved surfaces up and down. At this time, a plurality of on-chip microlenses 8 are formed so that the on-chip microlenses 8 of adjacent pixels do not contact each other.

  As described above, the solid-state imaging device 51 according to the second embodiment of the present invention, like the solid-state imaging device 50 according to the first embodiment, has a biconvex on-chip micro having a large curvature without deteriorating color reproducibility. The lens 8 can be formed. Thereby, the solid-state image sensor 51 can implement | achieve high condensing efficiency.

(Embodiment 3)
A solid-state imaging device 52 according to Embodiment 3 of the present invention is a modification of the solid-state imaging device 50 according to Embodiment 1, and includes a lattice pattern 26 having a trapezoidal cross-sectional shape.

  First, the structure of the solid-state imaging element 52 according to Embodiment 3 of the present invention will be described.

  FIG. 6 is a cross-sectional view showing the structure of the solid-state imaging device 52 according to Embodiment 3 of the present invention. Here, for ease of explanation, the same components as those of the solid-state imaging device 50 according to Embodiment 1 are denoted by the same reference numerals, and redundant description is omitted.

  A solid-state imaging device 52 illustrated in FIG. 6 includes a lattice-shaped pattern 26 instead of the lattice-shaped pattern 6 with respect to the solid-state imaging device 50 illustrated in FIG.

  The grid pattern 26 has a grid shape that has an opening above the light receiving unit 2 of each pixel and covers the boundary of the pixel when viewed from the top (upward direction in FIG. 6). The lattice pattern 26 has a trapezoidal cross-sectional shape in which the long side (long side of the two parallel sides) is in contact with the upper surface of the acrylic planarizing film 5. Then, when the acrylic film 7 under the on-chip microlens 8 is formed, the curvature of the upper surface of the acrylic film 7 that is downwardly convex can be determined by arbitrarily selecting the height and width.

  Next, a method for manufacturing the solid-state imaging element 52 according to Embodiment 3 of the present invention will be briefly described.

  First, the light receiving portion 2 is formed in the semiconductor substrate 1 by performing ion implantation or the like. Next, the insulating film 3 is laminated on the semiconductor substrate 1 on which the light receiving unit 2 is formed.

  Next, the color filter 4 is formed on the insulating film 3 by performing spin coating and patterning using a photomask. Next, the flattening on the color filter 4 is performed by forming the acrylic flattening film 5 on the color filter 4 using spin coating. Next, a synthetic resin film is spin-coated on the acrylic planarizing film 5, and patterning using a photomask is performed, thereby forming a lattice pattern 26 in the periphery of each pixel. At this time, the height of the lattice pattern 26 is 0.1 μm to 5.0 μm, the width of the long side of the trapezoid of the cross section is 0.1 μm to 5.0 μm, and the on-chip microlens 8 having a desired curvature. The height and width of the lattice pattern 26 are selected so as to form

  Next, the acrylic film 7 is spin-coated on the lattice pattern 26. At this time, the concavo-convex determined by the height and width of the grid pattern 26 is used to form the acrylic film 7 having a downward projection at the center of the pixel. Next, after a synthetic resin film is spin-coated on the acrylic film 7, a separate and independent resist pattern is formed on each pixel using a photomask. Next, the formed resist pattern is heat-flowed to form a biconvex on-chip microlens 8 having curved surfaces up and down. At this time, a plurality of on-chip microlenses 8 are formed so that the on-chip microlenses 8 of adjacent pixels do not contact each other.

  As described above, the solid-state imaging device 52 according to the third embodiment of the present invention is a biconvex on-chip micro having a large curvature without deteriorating the color reproducibility, like the solid-state imaging device 50 according to the first embodiment. The lens 8 can be formed. Thereby, the solid-state image sensor 52 can implement | achieve high condensing efficiency.

(Embodiment 4)
A solid-state imaging device 53 according to Embodiment 4 of the present invention is a modification of the solid-state imaging device 50 according to Embodiment 1, and includes a lattice pattern 36 having an inverted trapezoidal cross-sectional shape.

  First, the structure of the solid-state imaging element 53 according to Embodiment 4 of the present invention will be described.

  FIG. 7 is a cross-sectional view showing the structure of the solid-state imaging device 53 according to Embodiment 4 of the present invention. Here, for ease of explanation, the same components as those of the solid-state imaging device 50 according to Embodiment 1 are denoted by the same reference numerals, and redundant description is omitted.

  A solid-state image sensor 53 shown in FIG. 7 includes a grid pattern 36 instead of the grid pattern 6 as compared with the solid-state image sensor 50 shown in FIG.

  The grid pattern 36 has a grid shape that has an opening above the light receiving unit 2 of each pixel and covers the boundary of the pixel when viewed from the top (upward direction in FIG. 7). The lattice pattern 36 has an inverted trapezoidal cross-sectional shape with the lower side being a short side (short side of two parallel sides). Then, when the acrylic film 7 under the on-chip microlens 8 is formed, the curvature of the upper surface of the acrylic film 7 that is downwardly convex can be determined by arbitrarily selecting the height and width.

  Next, a method for manufacturing the solid-state imaging element 53 according to Embodiment 4 of the present invention will be briefly described.

  First, the light receiving portion 2 is formed in the semiconductor substrate 1 by performing ion implantation or the like. Next, the insulating film 3 is laminated on the semiconductor substrate 1 on which the light receiving unit 2 is formed.

  Next, the color filter 4 is formed on the insulating film 3 by performing spin coating and patterning using a photomask. Next, the flattening on the color filter 4 is performed by forming the acrylic flattening film 5 on the color filter 4 using spin coating. Next, after a synthetic resin film is spin-coated on the acrylic flattening film 5, patterning using a photomask is performed to form a lattice pattern 36 in the periphery of each pixel. Here, the height of the grid pattern 36 is 0.1 μm to 5.0 μm, the long side of the trapezoid of the cross section is 0.1 μm to 5.0 μm in width, and the on-chip microlens 8 having a desired curvature. The height and width of the lattice pattern 36 are selected so as to form

  Next, the acrylic film 7 is spin-coated on the lattice pattern 36. At this time, by using the unevenness determined by the height and width of the grid pattern 36, the acrylic film 7 that forms a downward protrusion is formed at the center of the pixel. Next, after a synthetic resin film is spin-coated on the acrylic film 7, a separate and independent resist pattern is formed on each pixel using a photomask. Next, the formed resist pattern is heat-flowed to form a biconvex on-chip microlens 8 having curved surfaces up and down. At this time, a plurality of on-chip microlenses 8 are formed so that adjacent on-chip microlenses 8 do not contact each other.

  As described above, the solid-state imaging device 53 according to the fourth embodiment of the present invention, like the solid-state imaging device 50 according to the first embodiment, has a biconvex on-chip micro having a large curvature without deteriorating color reproducibility. The lens 8 can be formed. Thereby, the solid-state image sensor 53 can implement | achieve high condensing efficiency.

(Embodiment 5)
A solid-state imaging device 54 according to Embodiment 5 of the present invention is a modification of the solid-state imaging device 50 according to Embodiment 1, and further includes a planarizing film 9 and a transparent plate 10 that transmits a visible light region. Prepare.

  First, the structure of the solid-state imaging device 54 according to Embodiment 5 of the present invention will be described.

  FIG. 8 is a cross-sectional view showing the structure of the solid-state imaging device 54 according to Embodiment 5 of the present invention. Here, for ease of explanation, the same components as those of the solid-state imaging device 50 according to Embodiment 1 are denoted by the same reference numerals, and redundant description is omitted.

  The solid-state imaging device 54 shown in FIG. 8 further includes a planarizing film 9 and a transparent plate 10 with respect to the solid-state imaging device 50 shown in FIG.

  The transparent plate 10 is formed of a plate-like material having a high transmittance in the visible light region. The transparent plate 10 is formed of, for example, a transparent inorganic oxide film material containing glass or a transparent acrylic resin.

  The planarizing film 9 is formed on the on-chip microlens 8 and the acrylic film 7 and transmits visible light. The planarizing film 9 is formed of an organic adhesive material, and bonds the transparent plate 10 to the on-chip microlens 8 and the acrylic film 7.

  Here, it is assumed that the solid-state image sensor 54 includes the grid pattern 6 having the same shape as the grid pattern 6 included in the solid-state image sensor 50 according to the first embodiment. Any of the lattice patterns 16, 26, and 36 described in Embodiments 2 to 4 may be provided.

  Then, when the acrylic film 7 under the on-chip microlens 8 is formed, the curvature of the upper surface of the acrylic film 7 that is downwardly convex can be determined by arbitrarily selecting the height and width.

  Next, a method for manufacturing the solid-state imaging element 54 according to Embodiment 5 of the present invention will be briefly described.

  First, the light receiving portion 2 is formed in the semiconductor substrate 1 by performing ion implantation or the like. Next, the insulating film 3 is laminated on the semiconductor substrate 1 on which the light receiving unit 2 is formed.

  Next, the color filter 4 is formed on the insulating film 3 by performing spin coating and patterning using a photomask. Next, the flattening on the color filter 4 is performed by forming the acrylic flattening film 5 on the color filter 4 using spin coating. Next, after a synthetic resin film is spin-coated on the acrylic flattening film 5, patterning using a photomask is performed to form a lattice pattern 6 in the peripheral portion of each pixel. Here, the lattice pattern 6 has a height of 0.1 μm to 5.0 μm and a width of 0.1 μm to 5.0 μm. The height and width of the lattice pattern 6 are selected so as to form an on-chip microlens 8 having a desired curvature.

  Next, an acrylic film 7 is spin-coated on the grid pattern 6. At this time, by using the unevenness determined by the height and width of the grid pattern 6, an acrylic film 7 having a downward protrusion is formed at the center of the pixel. Next, after a synthetic resin film is spin-coated on the acrylic film 7, a separate and independent resist pattern is formed on each pixel using a photomask. Next, the formed resist pattern is heat-flowed to form a biconvex on-chip microlens 8 having curved surfaces up and down. At this time, a plurality of on-chip microlenses 8 are formed so that adjacent on-chip microlenses 8 do not contact each other.

  Next, a planarizing film 9 is applied on the biconvex on-chip microlens 8. Next, a transparent transparent plate 10 having a high transmittance in the visible light region is attached to the top of the planarizing film 9.

  Through the above steps, the configuration of the solid-state imaging element 54 shown in FIG. 8 is generated.

  As described above, the solid-state imaging device 54 according to the fifth embodiment of the present invention, like the solid-state imaging device 50 according to the first embodiment, has a biconvex on-chip micro having a large curvature without deteriorating color reproducibility. The lens 8 can be formed. Thereby, the solid-state image sensor 54 can implement | achieve high condensing efficiency.

  The solid-state imaging devices 50 to 54 according to the first to fifth embodiments are typically realized as an LSI that is an integrated circuit.

  The name used here is LSI, but it may also be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

  1 to 8 are diagrams schematically showing the configurations of the solid-state imaging devices 50 to 54 according to the present invention, and configurations in which the respective configurations are modified for manufacturing reasons are also included in the present invention. . For example, the sides of each component described in the vertical and horizontal directions may be inclined at a predetermined angle from the vertical and horizontal. Moreover, although the corner | angular part and edge | side of each component are described linearly, at least one part may be rounded among the said corner | angular part and edge | side.

  Moreover, you may combine at least one part among the structures of the solid-state image sensors 50-54 which concern on the said Embodiments 1-5.

  The present invention can be used for a solid-state imaging device and a manufacturing method thereof, and is particularly effective for a solid-state imaging device having an on-chip microlens structure and a manufacturing method thereof. Therefore, the present invention can be applied to a digital still camera, a digital video camera, a mobile phone, and the like that include a solid-state imaging device.

DESCRIPTION OF SYMBOLS 1,101 Semiconductor substrate 2,102 Light-receiving part 3,103 Insulating film 4,105 Color filter 5,9,106 Flattening film 6,16,26,36 Grid pattern 7 Acrylic film 8,107 On-chip microlens 10 Transparent Plate 50, 51, 52, 53, 54, 100 Solid-state image sensor 104 Pattern

Claims (11)

A solid-state imaging device having a plurality of pixels arranged in a matrix,
A semiconductor substrate;
A photoelectric conversion unit included in each of the pixels and formed on the semiconductor substrate for converting incident light into an electrical signal;
A color filter formed above the plurality of photoelectric conversion units;
A lattice pattern formed on the color filter so as to cover the boundary of the pixels, each having an opening above the plurality of photoelectric conversion units,
A transparent film formed on the color filter and the lattice pattern;
An on-chip microlens included in each pixel and formed on the transparent film;
The upper surface of the transparent film in contact with each on-chip microlens is a downwardly convex shape,
The upper surface of the plurality of on-chip microlenses has an upward convex shape, and the lower surface has a downward convex shape. The solid-state imaging device according to claim 1, wherein a refractive index of the lattice pattern is smaller than a refractive index of the transparent film. The solid-state imaging device according to claim 1, wherein the lattice pattern absorbs light. The solid-state imaging device according to claim 1, wherein a cross-sectional shape of the lattice pattern is a square or a rectangle. The solid-state imaging device according to claim 1, wherein a cross-sectional shape of the lattice pattern is a triangle. The solid-state image sensor according to claim 1, wherein a cross-sectional shape of the lattice pattern is a trapezoid. The solid-state image sensor according to claim 1, wherein an upper surface of the color filter is flat. The solid-state imaging device further includes:
The solid-state image sensor of any one of Claims 1-7 provided with the 1st transparent planarization film | membrane formed between the said color filter and the said transparent film. The solid-state image sensor according to claim 1, wherein each of the plurality of on-chip microlenses is formed independently. The solid-state imaging device according to claim 1, wherein a refractive index of the on-chip microlens is higher than a refractive index of the transparent film. A second transparent planarization film formed on the on-chip microlens;
A transparent plate formed on the second transparent planarization film,
11. The solid-state imaging device according to claim 1, wherein the second transparent planarization film is formed of an organic adhesive material, and bonds the transparent plate and the on-chip microlens.

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