JP2009283978A - Solid-state image pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state image pickup device which suppresses variation of amounts of incident light to a photoelectric conversion part to prevent deterioration of a pickup image. <P>SOLUTION: The solid-state image pickup device has: the photoelectric conversion part which generates a signal electric charge according to the incident light; a plurality of color filters formed by division exposure for performing exposure by dividing an area into at least two or more exposure areas and having an overlap or gap between adjacent color filters; and a condenser lens which condenses the incident light to the photoelectric conversion part in the shape that makes the incident light pass through an area with identical spectral characteristics of the color filters. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device having a color filter for capturing a color image.

  Conventionally, a configuration shown in FIG. 4 is known as a solid-state imaging device used in a color video camera, a color still camera, or the like.

  FIG. 4 is a side sectional view showing the structure of a conventional solid-state imaging device.

  As shown in FIG. 4, the solid-state imaging device is configured to include a photoelectric conversion unit 2 that generates a signal charge corresponding to the amount of incident light in the vicinity of the surface of the semiconductor substrate 1. The photoelectric conversion unit 2 is provided for each of a plurality of pixels arranged in a grid. Note that an active element (not shown) is generally formed on the semiconductor substrate 1 together with the photoelectric conversion unit 2.

On the semiconductor substrate 1, a first interlayer insulating film 3 made of, for example, SiO ₂ having an opening on the photoelectric conversion unit 2 is deposited, and Al (aluminum) or the like is deposited on the first interlayer insulating film 3. Thus, the first wiring 4 patterned into a desired shape is formed.

  On the first interlayer insulating film 3, a second interlayer insulating film, a second wiring 6, a third interlayer insulating film 7, and a third wiring 8 are sequentially formed corresponding to the circuit pattern. . These interlayer insulating films and wirings do not need to have a three-layer structure, and may have a structure of two layers, one layer, or four layers or more.

  A protective film 9 made of, for example, SiON is deposited on the third interlayer insulating film 7 so as to cover the third wiring 8, and the first planarizing layer 10 made of, for example, acrylic resin is formed thereon. Is deposited.

  On the first planarization film 10, a color filter 11 that disperses incident light corresponding to each pixel is provided. The color filter 11 is formed using a photoresist containing pigments of three primary colors of red (R), green (G), and blue (B).

  On the color filter 11, a second planarizing layer 12 having optical transparency is deposited, and a microlens 13 that is a condensing lens for condensing incident light on the photoelectric conversion unit 2 is formed thereon. The

  In a solid-state imaging device having a large chip size, since the pattern formation area is larger than the exposure possible range by the exposure apparatus, the pattern formation area is divided into a plurality of exposure areas, and these divided patterns are joined together to obtain a desired Divided exposure for forming a pattern is employed (see, for example, Patent Document 1).

  Further, in recent solid-state imaging devices, there are cases where adjacent color filters are overlapped or formed with a gap due to dimensional variations and positional shifts of color filters with higher integration. Furthermore, since the corners of the color filter are formed in an arc shape due to a decrease in the resolution of the exposure apparatus, a gap in which the color filter is not formed also occurs in such corners. For example, Patent Document 2 discloses a technique for eliminating the overlapping and gaps of the color filters that cause deterioration of the captured image. Patent Document 2 describes a method of eliminating gaps between adjacent color filters by sequentially forming three color filters and then removing the upper color filter until the lowermost color filter is exposed. Yes.

JP-A-5-6849 JP-A-10-209410

  As shown in FIGS. 5A and 5B, when the solid-state imaging device 14 is divided and formed into two exposure areas, a first exposure area 15 and a second exposure area 16, as shown in FIGS. In addition, the first exposure region 15 and the second exposure region 16 may differ in the amount of overlap due to the position shift of the color filter and the size of the gap between the color filters.

  In such a case, the surface of the second flattening film formed on the color filter is not sufficiently flattened, and irregularities occur at the overlapping portions and gap portions of the color filter.

  For example, the concave portion of the second flattening film generated in the gap portion of the color filter acts like a lens and disperses incident light as shown in FIG. As a result, the light that has passed through the color filter due to the dispersion reaches the photoelectric conversion unit, and the amount of incident light varies among the pixels. Furthermore, since the light that has passed through the gap between the color filters is also reflected by the wiring or the like and eventually reaches the photoelectric conversion unit, there is a problem that the captured image is deteriorated.

  On the other hand, even in the overlapping part of the color filters, the amount of incident light reaching the photoelectric conversion unit is attenuated by passing through the thick color filter, so that the amount of incident light varies among pixels.

  In particular, when a color filter is formed by the above-described divided exposure, the amount of overlap of the color filters and the amount of gap between the first exposure area and the second exposure area are as shown in FIGS. 7 (a) and 7 (b). Because of the difference, the height of the unevenness generated on the surface of the second planarizing film is also different, and the variation in the amount of incident light appears remarkably in the captured image.

  The present invention has been made to solve the above-described problems of the prior art, and provides a solid-state imaging device that suppresses variations in the amount of incident light with respect to a photoelectric conversion unit and prevents deterioration of a captured image. For the purpose.

In order to achieve the above object, a solid-state imaging device of the present invention includes a photoelectric conversion unit that generates a signal charge according to incident light, and
A plurality of color filters formed by divided exposure in which exposure is performed by dividing into at least two exposure areas, and having overlapping or gaps between adjacent color filters;
A condensing lens that condenses the incident light on the photoelectric conversion unit, the incident light having a shape that allows the spectral characteristics of the color filter to pass through the same region;
Have

  The solid-state imaging device configured as described above has a condenser lens having a shape that allows incident light to pass through an area where the spectral characteristics of the color filter are the same. Since the change in the amount of incident light is reduced, variation in the amount of incident light between pixels is reduced.

  According to the present invention, the change in the amount of incident light to the photoelectric conversion unit due to the characteristics of the color filter is reduced by having the condensing lens having a shape that allows the incident light to pass through the region where the spectral characteristics of the color filter are the same. Therefore, the variation in the amount of incident light between pixels is reduced, and the deterioration of the captured image is prevented.

  In particular, in the configuration in which the color filter is formed using the divided exposure method, the variation in incident light amount between the divided regions is reduced, and thus the captured image is further prevented from deteriorating.

It is a sectional side view which shows the structure of 1st Embodiment of the solid-state image sensor of this invention. It is a sectional side view which shows the structure of 2nd Embodiment of the solid-state image sensor of this invention. It is a graph which shows the relationship of the height of the unevenness | corrugation which arises on the surface of the 2nd planarization film with respect to the film thickness of a 2nd planarization film. It is a sectional side view which shows the structure of the conventional solid-state image sensor. It is a top view which shows an example of the solid-state image sensor to divide and expose. It is a top view which shows the mode of the position shift of the color filter which the solid-state image sensor shown in FIG. 5 has. FIG. 6 is a side cross-sectional view illustrating a state of a positional shift of a color filter included in the solid-state imaging device illustrated in FIG. 5.

  Next, the present invention will be described with reference to the drawings.

  FIG. 1 is a side sectional view showing the configuration of the first embodiment of the solid-state imaging device of the present invention. FIG. 2 is a side sectional view showing the configuration of the second embodiment of the solid-state imaging device of the present invention.

  As shown in FIG. 1, in the first embodiment of the solid-state imaging device of the present invention, the second flattening film 22 deposited on the color filter 21 is formed thicker than before, and the unevenness generated on the surface thereof. To be sufficiently small. Specifically, the thickness of the second planarization film 22 is set so that the depth (height) of the unevenness generated on the surface of the second planarization film 22 is 0.2 μm or less.

  In such a configuration, since the change in the amount of incident light to the photoelectric conversion unit 2 due to the shape of the second planarization layer 12 is reduced, the variation in the amount of incident light between pixels is reduced, and the captured image is deteriorated. Is prevented.

  On the other hand, in the second embodiment of the solid-state imaging device of the present invention, the shape of the microlens 23 is set so that incident light to the photoelectric conversion unit does not pass through the overlapping portion of the color filters. Specifically, as shown in FIG. 2, when the pixel diameter is L, the outermost optical path of the incident light and the upper surface of the color filter 11 at positions of 0.1 L to 0.25 L inward from both ends of the pixel. The diameter and thickness of the microlens 23 are set so that.

  In such a configuration, since the change in the amount of incident light to the photoelectric conversion unit 2 due to the characteristics of the color filter 11 is reduced, the variation in the amount of incident light between pixels is reduced, and deterioration of the captured image is prevented. .

  In particular, if the configuration of the first embodiment or the second embodiment is applied to a solid-state imaging device in which a color filter is formed using the divided exposure method, the variation in the amount of incident light between the divided areas is achieved. As a result, the deterioration of the captured image is further prevented.

  The other configuration is the same as that of the conventional solid-state imaging device shown in FIG. Therefore, in FIG. 1 and FIG. 2, the same reference numerals are given to the same components as those in the prior art.

  1 and 2 illustrate a configuration in which the microlens 23 and the color filter 11 are separately provided, the microlens 23 may have a configuration having the function of the color filter 11.

  Next, embodiments of the solid-state imaging device of the present invention will be described with reference to the drawings.

  This example is a specific manufacturing example of the solid-state imaging device of the first embodiment.

  As the material of the second planarization film 22 formed on the color filter 11 shown in FIG. 1, PGMA (polyglycidyl methacrylate), PMMA (polymethyl methacrylate), polyimide, or the like is usually used. More specifically, for example, FVR (manufactured by Fuji Pharmaceutical), Optmer SS (manufactured by JSR), Optmer LC (manufactured by JSR), Optmer AH (manufactured by JSR) and the like are known as suitable materials.

In this example, the above-described optomer AH was used to form solid-state imaging devices each having the second planarizing film 22 having thicknesses of 0.5 μm, 1.0 μm, and 1.5 μm. At this time, the depths of the recesses formed on the second planarizing film 22 were 0.31 μm, 0.21 μm, and 0.10 μm. FIG. 3 shows the relationship between the thickness of the second planarizing film 22 and the height of the irregularities generated on the surface of the second planarizing film. The refractive index n _D of Optomer AH (manufactured by JSR) is 1.55.

  Microlenses 23 were respectively formed on the second planarizing films 22 having different thicknesses, and three types of solid-state imaging devices were manufactured. The structure from the semiconductor substrate 1 including the wiring and the interlayer insulating film to the color filter 11 is the same as the conventional configuration shown in FIG.

  When imaging was performed using the solid-state imaging device, the voltage difference of the pixel signal between adjacent exposure regions formed by the divided exposure was such that the unevenness of the second planarization film 22 was 0.2 μm in the pixel region. It was confirmed that there was no problem in image quality if the settings were as follows. That is, the thickness of the second planarizing film may be set to about 1.0 μm or more.

DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Photoelectric conversion part 3 1st interlayer insulation film 4 1st wiring 5 2nd interlayer insulation film 6 2nd wiring 7 3rd interlayer insulation film 8 3rd wiring 9 Protective film 10 1st Planarization layer 11R, 11G, 11B Color filter 12, 22 Second planarization layer 13, 23 Microlens

Claims (6)

A photoelectric conversion unit that generates a signal charge according to incident light;
A plurality of color filters formed by divided exposure in which exposure is performed by dividing into at least two exposure areas, and having overlapping or gaps between adjacent color filters;
A condensing lens that condenses the incident light on the photoelectric conversion unit, the incident light having a shape that allows the spectral characteristics of the color filter to pass through the same region;
A solid-state imaging device. The condenser lens is
The solid-state imaging device according to claim 1, wherein the incident light has a shape that allows the color filter to pass through a region having the same film thickness. The condenser lens is
When the pixel diameter is L, the outermost optical path of the incident light at the position of 0.1 L to 0.25 L inward from both ends of the pixel, and the surface facing the condenser lens of the color filter The solid-state imaging device according to claim 1, wherein the solid-state imaging device has a matching shape. A wiring layer formed between the photoelectric conversion unit and the color filter;
4. The solid-state imaging device according to claim 1, wherein the wiring layer has a wiring arranged so as not to intersect an outermost optical path of the incident light. 5.   The wiring layer formed between the photoelectric conversion unit and the color filter is a plurality of layers, and has a protective layer that covers a wiring closest to the color filter among the plurality of wiring layers, and the protective layer The solid-state imaging device according to claim 4, further comprising an averaging layer disposed between the color filters.   The solid-state imaging device according to claim 1, further comprising a second flattening layer disposed between the color filter and the condenser lens.

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