JP2009122521A - Color filter forming method, solid-state imaging device, and image display device - Google Patents

Abstract

The present invention eliminates uneven application of color filters.
A green color photoresist is spin-coated on a planarizing layer (st1). Each process of exposure, development, and heat treatment is performed (st2), and a green color filter having a uniform thickness formed in a stripe shape is obtained. Next, a blue color photoresist is spray applied (st3). A blue color photoresist enters the groove-like portion where the green color filter is not formed. Each process described above is performed (st4) to obtain a blue color filter having a uniform thickness. Next, a red color photoresist is applied by spraying (st5) and enters the groove. Each process described above is performed (st6) to obtain a red color filter having a uniform thickness.
[Selection] Figure 2

Description

  The present invention relates to a method for forming a color filter, and more particularly to a method for forming a color filter of a solid-state imaging device or an image display device.

In a solid-state imaging device such as a CCD, red (R), green (G), and blue (B) color filters are formed in a striped or checkered pattern on a planarizing layer (Patent Documents 1 and 2). . In order to form this color filter, a pigment-dispersed color photoresist of the first color composed of a pigment, resin, photosensitizer, solvent, and additive is placed on a solid-state image sensor covered with a planarizing layer composed of a transparent resin. A first color filter is formed by spin coating, exposure, development, and heat treatment at about 200 to 250 ° C. Similarly, the second color and the third color are sequentially formed to form a three-color color filter.
JP 2004-311557 A JP-A-10-262260

  However, when the color filter of the first color is formed in a stripe shape, if the color photoresist of the second color is spin-coated, the color photoresist tends to flow in the direction along the stripe, but a step in the direction perpendicular to the stripe. It is hard to flow by the influence of. For this reason, coating unevenness occurs in a direction orthogonal to the stripe. When such coating unevenness occurs, the film thickness of the color filter becomes non-uniform, causing a problem of causing non-uniformity in sensitivity even among pixels of the same color.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a color filter forming method, a solid-state imaging device, and an image display device that eliminate uneven application of color filters.

  In the color filter forming method of the present invention, a color photoresist having a colorant dispersed on a flat predetermined member is applied to a uniform film thickness, and the process of patterning the coating film is repeated for a predetermined number of colors as many times as necessary. In the method of forming a color filter, the first color filter formed first is striped, and the color photoresist corresponding to the second color filter formed next is applied by spraying. It is characterized by being performed by spray coating.

  A solid-state imaging device according to the present invention includes a color filter formed by the color filter forming method according to claim 1. An image display apparatus according to the present invention includes a color filter formed by the color filter forming method according to claim 1.

  According to the color filter forming method, solid-state imaging device, and image display apparatus of the present invention, when the first color filter is formed in a stripe shape, the second color of the color photoresist is applied by spraying. There is no influence by the stripe pattern of the color filter of the color, and the coating unevenness of the color filter of the second color can be eliminated.

  In FIG. 1 showing the solid-state imaging device of the present invention, a solid-state imaging device 10 is configured as an interline transfer type CCD image sensor, and is formed of a photodiode or the like on a semiconductor substrate 11 (see FIG. 3). 12 are arranged in a two-dimensional matrix (square lattice) along a row direction (X direction) and a column direction (Y direction) orthogonal thereto.

  The pixel 12 includes corresponding green (G), blue (B), and red (R) color filters 14 to 16 on the light incident side of a light receiving element (photoelectric conversion element) 13 (see FIG. 3) made of a photodiode. A microlens (not shown) is disposed, and signal charges corresponding to the amount of light of each color are generated from incident light by photoelectric conversion and accumulated.

  The green color filter 14 has an elongated shape extending in the Y direction, and has a stripe shape arranged in every other row in the X direction. The blue and red color filters 15 and 16 are sandwiched between the color filters 14, each have a length of two pixels, and are alternately arranged in the X direction and the Y direction, respectively. Although FIG. 1 shows only a range of 6 rows and 5 columns, actually, a large number of pixels are repeatedly arranged in the row direction and the column direction.

  A method of forming the color filters 14 to 16 configured as described above will be described with reference to the flowchart of FIG. In FIG. 3A showing the color filter forming process of the cross-sectional portion of the solid-state imaging device 10 taken along the line III-III in FIG. 1, a planarizing layer 18 made of a transparent resin that smoothes the surface of the semiconductor substrate 11 is formed. On top, a green color photoresist 20 as the first color is spin-coated using a spinner device (st1). The color photoresist 20 is a pigment dispersion type composed of a green pigment, a resin, a photosensitive agent, a solvent, and an additive, and is a negative type in which the exposed portion remains.

  Next, pattern exposure is performed on the color photoresist 20 through the mask 21 in which the stripe-shaped opening pattern is formed (FIG. 3B). Next, development is performed using an organic alkali developer. Next, heat treatment is performed to cure the patterned color photoresist 20 (st2). Thereby, a green color filter 14 having a uniform thickness formed in a stripe shape is obtained (FIG. 3C).

  Next, as shown in FIG. 5, a blue pigment-dispersed negative color photoresist 22 as the second color is applied by spray coating (st3). In this spray coating, the color photoresist 22 is sprayed by the nozzle 24, and the color photoresist 22 is spray-coated on the wafer 25 on which a large number of solid-state imaging devices 10 are formed.

  By this spray application, the color photoresist 22 enters the groove-like portion 26 where the color filter 14 is not formed (FIG. 3D). Next, the same processing as that for forming the green color filter 14 described above is performed (st4) (FIG. 3E), and the blue color filter 15 is obtained (FIG. 4A).

  Next, a red pigment-dispersed negative color photoresist 27 as the third color is spray-coated on the wafer 25. As a result, the color photoresist 27 enters the groove-like portion 26 where the color filters 14 and 15 are not formed (FIG. 4B). Next, the same processing as that for forming the green color filter 14 described above is performed (st4) (FIG. 4C), and the red color filter 16 is obtained (FIG. 4D).

  After the first color filter 14 is formed, the spin coating method is not used, and the spray coating method is used. Therefore, the first color filter is not affected by the stripe pattern of the color filter and is uniform for all the colors. A color filter with a sufficient thickness can be formed, and so-called uneven sensitivity can be prevented.

  As a result, in order to make the thickness of the color filter uniform, it is possible to omit a planarization step by chemical mechanical polishing performed in a general color filter forming step. This can also contribute to reducing the number of manufacturing steps of the solid-state imaging device.

  In the embodiment described above, the color photoresist of the first color is spin-coated and the color photoresist of the second and third colors is spray-coated. However, the present invention is not limited to this. (The color filter pattern at the time when the second color filter is formed is not striped, and there is no anisotropy in the direction in which the resist flows by spin.) ).

  In the above embodiment, the color photoresist is a negative type, but it may be a positive type. In the above embodiment, the color pixel is configured as a pixel that detects light of three primary colors of red (R), green (G), and blue (B), but the present invention is not limited to this. Instead, the color pixels may be configured as pixels that detect complementary color light of cyan (C), magenta (M), and yellow (Y).

  In the above embodiment, the color filter is formed on the flattening layer of the solid-state imaging device. However, the present invention is not limited to this, and for example, a color used in an image display device such as a liquid crystal display. It can also be applied to the formation of a filter.

It is a schematic plan view which shows the structure of a solid-state image sensor. It is a schematic diagram which shows a square lattice-like pixel arrangement | sequence. It is explanatory drawing which shows the formation process of the color filter of the cross-sectional part in the III-III line of FIG. FIG. 4 is an explanatory diagram illustrating a color filter forming process continued from FIG. 3. It is explanatory drawing which shows spray application roughly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Solid-state image sensor 11 Semiconductor substrate 12 Pixel 13 Light receiving element 14-16 Color filter 18 Flattening layer 20, 22, 27 Color photoresist 26 Groove | grooved part

Claims (3)

In a method of forming a color filter by applying a color photoresist in which a colorant is dispersed on a flat predetermined member to a uniform film thickness, and repeating a process of patterning the coating film a predetermined number of colors.
The first color filter formed first is striped, and the color photoresist corresponding to the second color filter formed next is applied by spray application. A characteristic color filter forming method.   A solid-state imaging device comprising a color filter formed by the method for forming a color filter according to claim 1.   An image display device comprising a color filter formed by the method for forming a color filter according to claim 1.

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