JPH0745804A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To suppress the influence of the reflection from a shading film by the exposure for forming a pattern so as to prevent the disturbance of patterns or mixing of colors by forming a color filter low in transmittance to exposure wavelength so that it may cover a desired light receiving part and all the shading films, as the first layer. CONSTITUTION:A yellow cover filter 7a lowest in transmittance to exposure wavelength covers the flattening film 5b above an photo-electric conversion region 3 where the yellow color filter 7a is to be made and the shading film 6 provided on all the charge transfer region 2. Hereby, the influence of the reflection at the shading film in exposure in the subsequent state of a conventional process without forming the film for preventing the reflection at the shading film, and a solid image pickup device where the disturbance of patterns of the color filter and the mixing of colors are less than before can be gotten.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device having a color filter.

[0002]

2. Description of the Related Art FIG. 3A is a sectional view of a solid-state image pickup device having a first conventional color filter. Figure 3
As shown in (a), in a conventional solid-state imaging device using a color filter, a light-shielding film 6 made of metal or the like is formed above the charge transfer region 2 formed in the semiconductor substrate 1. The light-shielding film 6 is for preventing incident light from directly entering the charge transfer region 2 instead of the photoelectric conversion region 3 and generating a false signal such as smear.

However, as the size of the solid-state image pickup device and the size of the chip have been reduced and the cell size has been reduced, as shown in FIG. 4, during the exposure for forming the color filter, the light reflected by the light-shielding film causes Distortion of the pattern shape of the color filter, color mixing 9, etc. occur. FIG. 4 is a diagram for explaining the problems of the conventional solid-state imaging device.

Therefore, as shown in the sectional view of the solid-state image pickup device using the second conventional color filter of FIG. 3B, the light shielding film 6 is formed on the light-shielding film 6 by the same method as the color filter formation before the color filter formation. The light-shielding film antireflection film 8 dyed with a dye having a low transmittance with respect to the exposure wavelength such as black is formed so as to cover, and the reflection from the light-shielding film 6 is suppressed to prevent the pattern shape from being disturbed.

[0005]

However, the above-mentioned second problem
When the conventional solid-state image pickup device is used, the number of steps for forming the light-shielding film antireflection film 8 increases, and the flatness is impaired because the color filter 7 is formed on the light-shielding film antireflection film 8. There was a point.

The present invention provides a solid-state image pickup device using a color filter, which can prevent the pattern shape of the color filter from being disturbed by the reflected light from the light-shielding film while maintaining the flatness without increasing the number of steps. The purpose is to

[0007]

According to another aspect of the present invention, there is provided a solid-state image pickup device in which a photoelectric conversion portion and a charge transfer portion are formed on a surface of a semiconductor substrate, and a light shielding film is formed above the charge transfer portion. In the solid-state imaging device in which a plurality of types of monochromatic color filters are stacked and formed, among the monochromatic color filters, a monochromatic color filter having a transmittance for an exposure wavelength of a predetermined value or less is formed in the lowermost layer, and It is characterized in that the monochromatic color filter formed in the lowermost layer is also formed above the light shielding film.

The solid-state image pickup device of the present invention according to claim 2 is characterized in that the transmittance of the monochromatic color filter formed in the lowermost layer with respect to the exposure wavelength is 20% or less. The solid-state imaging device of.

[0009]

The present invention suppresses the influence of reflection from the light-shielding film due to exposure during pattern formation, and prevents pattern disturbance and color mixing.

[0010]

The present invention will be described in detail below based on an example.

FIG. 1A is a plan view of a solid-state image pickup device having a color filter according to an embodiment of the present invention.
(B) is AA 'in FIG. 1 (a) of the solid-state imaging device.
FIG. 1C is a cross-sectional view, and FIG.
FIG. 2B is a sectional view taken along line BB ′ in FIG. 2A, in which FIG. 2A shows the transmittances of yellow, magenta, and cyan with respect to the exposure wavelength, and FIG. 2B shows the transmittances of blue, green, and red with respect to the exposure wavelength. Indicates.

In FIG. 1, 1 is a semiconductor substrate, 2 is a charge transfer region, 3 is a photoelectric conversion region, 4a is a first gate electrode,
4b is a second gate electrode, 5a is a first flattening film, 5b is a second flattening film, and 6 is a light shielding film.

The yellow color filter 7a, which has the lowest transmittance for the exposure wavelength, is provided above the photoelectric conversion area 3 where the yellow color filter 7a is to be formed and on all the charge transfer areas 2. The upper surface of the flattening film 5b above the light shielding film 6 is covered.

Further, 7b is a magenta color filter, and 7c is a cyan color filter.

The color filter used in the G (green) region in FIG. 1A is formed by stacking a yellow color filter 7a and a cyan color filter 7c as shown in FIG. 1B. To be done.

Next, a manufacturing process of a solid-state image pickup device having a color filter according to an embodiment of the present invention will be described. In the examples, a case will be described in which complementary color (yellow, magenta, cyan) color filters are exposed with G line (wavelength 436 nm) to form a pattern of the color filters.

First, a charge transfer section (not shown) and a photoelectric conversion section (not shown) are formed on the semiconductor substrate 1.
Subsequently, the first gate electrode 4a, the second gate electrode 4b, the first flattening film 5a, and the second flattening film 5b are formed.

Next, in the case of using a complementary color filter, as shown in FIG. 2A, the transmittance for yellow G line wavelength is about 10%, which is the lowest. Formed on the first layer. First, on the second flattening film 5b, a color filter material having photosensitivity to the G line is applied in an amount of about 0.5 to 0.8 μm.
As shown in (a), in addition to the regions where the yellow and green color filters are formed, a pattern covering the entire light-shielding film 6 is exposed and formed. Regarding the exposure, in order to suppress the influence of the reflection from the light-shielding film 6 as much as possible, the exposure amount (900 to 12
00mJ / cm ²⁾ less than 500~700mJ / c
The dose amount is m ² . Dose amount is 500mJ / cm ²
In the following, the adhesion of the pattern is deteriorated due to insufficient exposure, and the film of the pattern is roughened or peeled off.
At cm ² or more, disturbance of the pattern shape or color mixture occurs due to reflection from the light shielding film 6 below due to overexposure.

Next, in order to supplement the adhesion of the pattern by the amount of exposure that is set smaller than in the prior art, after exposure, a beta treatment is performed in an oven at about 90 ° C. for about 20 minutes, and then a development treatment is performed.

Next, a yellow color filter 7a having an antireflection effect from the light-shielding film 6 at the time of exposure is formed by dyeing with a yellow dye having a low transmittance of about 10% with respect to the G line wavelength. . The yellow color filter 7a can suppress the reflection from the light-shielding film 6 at the time of exposure when forming the subsequent color filters 7b and 7c, a microlens (not shown), etc., and prevent the pattern from being disturbed.

Thereafter, the magenta color filter 7b, the cyan color filter 7c, the microlens (not shown) and the like are formed by the same steps as in the prior art.

The complementary color filter is connected to the I line (wavelength 365
2), the cyan color filter 7c has a low transmittance of about 10% with respect to the I-line wavelength as shown in FIG. 2A, so it is preferable to form it in the first layer. If the ratio is 20% or less, it is effective in preventing reflection from the light-shielding film 6, so that the yellow color filter 7a may be formed in the first layer. If the transmittance exceeds 20%, the antireflection effect is halved, and the pattern shape of the color filter or the like is likely to be disturbed or color mixture occurs.

Furthermore, primary colors (blue, green, red)
2B, the transmittance of the red color filter and the green color filter is as low as about 10% for the G line wavelength and the I line wavelength, respectively. Therefore, it is desirable to form a red or green color filter in the first layer.

[0024]

As described above in detail, according to the present invention, a color filter having a low transmittance for an exposure wavelength is formed on the first layer so as to cover a desired light receiving portion and all light shielding films. By doing so, it is possible to suppress the influence of reflection from the light-shielding film at the time of the exposure in the subsequent process in the conventional process without newly forming an anti-reflection film from the light-shielding film, and the pattern of the color filter is disturbed more than before. Also, a solid-state imaging device with less color mixture can be obtained.

[Brief description of drawings]

1A is a plan view of a solid-state imaging device having a color filter according to an embodiment of the present invention, FIG. 1B is a sectional view taken along line AA ′ of FIG. 1A, and FIG. 4A is a sectional view taken along line BB ′ of FIG.

FIG. 2A is a diagram showing a relationship between an exposure wavelength and a transmittance of a complementary color filter, and FIG. 2B is a diagram showing a relationship between an exposure wavelength and a transmittance of a primary color filter.

3A is a cross-sectional view of a solid-state imaging device having a first conventional color filter, and FIG. 3B is a cross-sectional view of a solid-state imaging device having a second conventional color filter.

FIG. 4 is a diagram for explaining problems of the conventional technique.

[Explanation of symbols]

 1 semiconductor substrate 2 charge transfer region 3 photoelectric conversion region 4a first gate electrode 4b second gate electrode 5a first flattening film 5b second flattening film 6 light-shielding film 7a yellow color filter 7b magenta color filter 7c cyan color filter

Claims (2)

[Claims] 1. A solid-state imaging device comprising: a photoelectric conversion section and a charge transfer section formed on a surface of a semiconductor substrate; a light-shielding film formed above the charge transfer section; and a plurality of types of monochromatic color filters formed in layers. Among the monochromatic color filters, a monochromatic color filter having a transmittance for an exposure wavelength of a predetermined value or less is formed in the lowermost layer, and the monochromatic color filter formed in the lowermost layer is also formed above the light shielding film. The solid-state imaging device is characterized by being. 2. The solid-state imaging device according to claim 1, wherein the monochromatic color filter formed in the lowermost layer has a transmittance of 20% or less for an exposure wavelength.