JPH04103166A - Color solid-state imaging device and its manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a color solid-state imaging device formed with a color filter and capable of capturing color images, and a method for manufacturing the same.

[Conventional technology]

Conventionally, there are the following methods for manufacturing this type of color solid-state imaging device. First, on a substrate on which photoelectric conversion parts and charge transfer parts are alternately formed, transfer electrodes are formed so as to face the charge transfer parts. Next, on the transfer electrode, so as to cover the transfer electrode,
In particular, a light-shielding film made of a metal with high optical reflectance such as A2-5i alloy without surface treatment is formed. Next, a flat layer is formed on the photoelectric conversion section and the light shielding film. Next, a color filter is patterned and formed on the flat layer by exposure so as to face the photoelectric conversion section.

[Invention or problem to be solved]

However, in the above-mentioned conventional manufacturing method for color solid-state imaging devices, a light-shielding film made of a metal with high optical reflectivity such as AQ81 alloy without any particular surface treatment is formed, so after forming the light-shielding film, color In order to pattern the filter, the light when exposing the color filter from above is reflected on the complicatedly shaped upper surface of the light shielding film. Then, the reflected light exposes the end portion of the color filter from below, and as shown in FIG. 3, the shape of the end portion of the color filter becomes extremely disordered and irregular. For this reason, in conventional color solid-state imaging devices manufactured by the above-mentioned conventional manufacturing method and the manufacturing method described above, color mixing with adjacent color filters of different colors occurs at the ends of the color filters. There is a problem in that this causes stiffness and roughness in the image capture screen. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a color solid-state imaging device and a method for manufacturing the same, which can suppress reflection of light incident on a light-shielding film on the upper surface of the light-shielding film.

[Means to solve the problem]

In order to achieve the above object, the color solid-state imaging device of the present invention includes a substrate on which photoelectric conversion parts and charge transfer parts are alternately formed, a transfer electrode formed to face the charge transfer part, and a A light-shielding film formed on the transfer electrode to cover the transfer electrode, an anti-reflection film formed in close contact with the light-shielding film, and a flat layer formed on the anti-reflection film and on the photoelectric conversion section. , a color filter is provided on the flat layer so as to face the photoelectric conversion section. Further, in the method for manufacturing a color solid-state imaging device of the present invention, a transfer electrode is formed on a substrate on which photoelectric conversion sections and charge transfer sections are alternately formed, so as to face the charge transfer sections, and then,
A light-shielding film is formed on the transfer electrode so as to cover the transfer electrode, an anti-reflection film is formed in close contact with the light-shielding film, and then an anti-reflection film is formed on the anti-reflection film and the photoelectric conversion film is formed. The method is characterized in that a flat layer is formed on the photoelectric conversion portion, and then a color filter is patterned and formed on the flat layer by exposure so as to face the photoelectric conversion portion. Further, in the method for manufacturing the color solid-state imaging device, a metal or alloy with high optical reflectance is used as the material of the light shielding film, and the upper surface of the metal or alloy with high optical reflectance is treated with oxidation for the anti-reflection film. It is desirable to form the

[Effect]

In the color solid-state imaging device of the present invention, since the anti-reflection film is formed in close contact with the light-shielding film covering the transfer electrode, after the anti-reflection film is formed, it is placed on the flat layer facing the photoelectric conversion section. When a color filter is patterned and formed by exposure, the light incident on the antireflection film during the exposure is absorbed by the antireflection film. Therefore, the reflection of light during the exposure at the anti-reflection film and the light-shielding film is suppressed, and the end portions of the color filter are prevented from being exposed from below, and the end portions of the color filter are prevented from being exposed to light from below. Disturbing the shape can be suppressed. Therefore, the occurrence of color mixture with adjacent color filters of different colors at the end portions of the color filter and the roughness of the image on the imaging screen can be suppressed. Moreover, the light incident on the antireflection film from the end of the color filter is absorbed by the antireflection film, and reflection is suppressed. Therefore, it is possible to prevent the light from being reflected by the anti-reflection film, diffusely reflected by the protective film, flat layer, or color filter, and entering the photoelectric conversion section, thereby preventing the imaging screen from becoming unclear. In the method for manufacturing a color solid-state imaging device of the present invention, a light-shielding film is formed to cover the transfer electrode, and an anti-reflection film is formed in close contact with the light-shielding film, so that after the formation of the anti-reflection film, When a color filter is formed on the flat layer by turning seven times by exposure so as to face the photoelectric conversion part, the light incident on the anti-reflection film during the exposure is absorbed by the anti-reflection film. Therefore, the reflection of light during the exposure at the locations of the anti-reflection film and the light-shielding film is suppressed, and the end portions of the color filters are prevented from being exposed from below, and the edges of the color filters are prevented from being exposed to light from below. Disturbing the shape of the part can be suppressed. Therefore, the occurrence of color mixture with adjacent color filters of different colors at the ends of the color filter and the roughness of the image on the imaging screen can be suppressed. In addition, when a metal or alloy with high optical reflectance is used as the material of the light shielding film and the antireflection film is formed by oxidizing the upper surface of the metal or alloy with high optical reflectance, A preventive film is easily formed.

【Example】

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments. FIG. 1 is a sectional view of an embodiment of the color solid-state imaging device of the present invention. This color solid-state imaging device has a photoelectric conversion section 2 and a charge transfer section 3 formed alternately, and a transfer electrode 5, which is surrounded by an insulating layer 4 and faces the charge transfer section 3, formed on two substrates I. There is. A light shielding film 6 made of A(!-81 alloy) is formed on the insulating layer 4 to face the transfer electrode 5. The light shielding film 6 shields the transfer electrode 5 and the charge transfer section 3 from light. On the light shielding film 6,
An antireflection film 7 is formed to prevent reflection of light incident on the light shielding film 6. A first protective film 8 is formed in close contact with the antireflection film 7, the entirety of the insulating layer 4, and the light shielding film 6. A flat layer 9 is formed in close contact with the first protective film 8. The flat layer 9 has a role of alleviating the level difference in the layer below the flat layer 9. On the flat layer 9,
Color filters IO and 1 whose central part faces the photoelectric conversion section 2 and whose end parts face the anti-reflection @7
1 is formed. Here, the color filter 10
．． 11 is formed by patterning by exposure, the light incident on the anti-reflection film 7 during exposure is absorbed by the anti-reflection film 7. Therefore, it is possible to suppress the reflection of light during the exposure at the portion of the antireflection film 7, and it is possible to suppress the end portions of the color filters 10, 11 from being exposed from below. Therefore, it is possible to suppress the disturbance of the shape of the end portion of the color filter 10.11, and it is possible to suppress the occurrence of color mixture of the color filter 1O11 and the roughness of the image on the imaging screen. A second protective film 12 for protecting the color filters 10 and 11 is formed on the color filter 10.11. Said insulating layer 4. first protective film 8,
Both the flat layer 9 and the second protective film 12 are made of transparent films. In the above configuration, when the light incident from the second protective film 12 reaches the photoelectric conversion section 2, the photoelectric conversion section 2 generates a signal charge. The signal charge moves within the charge transfer section 3 in response to a signal from the transfer electrode 5. Also,
The light reaching the anti-reflection film 7 from the end of the color filter TO11 is absorbed by the anti-reflection film 7 and is suppressed from being reflected. Therefore, the above-mentioned light is
It is reflected by the insulating layer 4. It is possible to prevent the light from being diffusely reflected by the first protective film 8, the flat layer 9, and the color filters 10 and 11 and entering the charge conversion section 2, and it is possible to prevent the image capturing screen from becoming unclear. Next, a method of manufacturing the color solid-state imaging device of the above embodiment will be explained. First, as shown in FIG. 2, a transfer electrode 5 covered with an insulating layer 4 made of a transparent film is placed on a substrate 1 on which photoelectric conversion sections 2 and charge transfer sections 3 are alternately formed. Formed so as to face. Next, as shown in FIG. 2, by sputtering etc.
The entire surface of the above insulating layer 4 is covered with AQ-Si alloy of 0.8 to 12
The AC-Si alloy layer 21 is formed by coating with a thickness approximately equal to μ dust. Next, as shown in FIG. 2, an acid-resistant resist 22 is patterned by photolithography on a portion of the AO-5i alloy layer 21 covering the insulating layer 4 that does not face the transfer electrode 4. Form. Above resist 2
The portion of the Aid-5i alloy layer 21 that is not covered by the mask 2 is the portion that should become the light shielding film 6. Next, the surface of the portion of the AQ-8i alloy layer 21 that is to become the light shielding film 6 is anodized by an anodizing method, and the first
The antireflection film 7 shown in the figure is formed. During this anodization,
Sulfuric acid or nitric acid is used as the electrolytic solution, and an electrode made of Pb, AC, etc. is used as the cathode. Further, although the anodic oxidation is generally performed at room temperature, the temperature of the electrolytic solution locally reaches 120 to 150°C in the area where the reaction between the electrolytic solution and the AQ-81 alloy layer 21 occurs. During oxidation, it is necessary to stir the electrolytic solution in order to protect the resist 22. In addition, when using sulfuric acid in the above electrolytic solution, "2 sulfuric acid is 3
Use as a ~12% aqueous solution. When the ion current density during the anodic oxidation is 127 A/dm', the above A(!-
The formation rate of oxide film on 3i alloy layer 21 is 3725 A/m
In this case, an oxide film with a thickness of about 7000 A can be easily obtained in about 2 minutes. This oxide film becomes the antifouling film 7. In the anodic oxidation, the upper 82A (!-81 in the Si alloy layer 21 remains as an impurity in the oxide film without being dissolved into the electrolytic solution during the formation of the oxide film. Since the light incident on the anti-reflection film 7 made of material is absorbed and scattered by the residual S1, the anti-reflection film 7 itself becomes gray or black, and the reflectance of the surface of the anti-reflection film 7 is low.Next Then, the resist 22 and the anodized A(!
After thoroughly washing the -3i alloy layer 21 with water, the resist 22 is peeled off. Next, the areas where the antireflection film 7 was formed by the above-mentioned anodic oxidation, the wiring, etc. AI! A resist is patterned and formed on the J-9i alloy layer 21 in the areas where it is required by photolithography.Next, by dry etching, the unnecessary areas A(!-) where the resist is not patterned are formed. 5i alloy layer 2
Remove 1. Next, a first protective film 8 made of a transparent film is formed in close contact with the antireflection film 7, the wire-continuous layer 4, and the light shielding film 6. Next, a flat layer 9 made of transparent resin is formed in close contact with the first protective film 8 . Next, a color filter 10.11 is formed on the flat layer 9 by patterning by exposure, the center portion facing the photoelectric conversion portion 2 and the end portion facing the antireflection film 7. Here, the color filter 10. When exposing It, the light reaching the anti-reflection film 7 is suppressed from being reflected on the anti-reflection film 7 because the reflectance of the anti-reflection film 7 is low as described above, and the light reaches the color filter. Since the end portions of the color filters 10.11 can be prevented from being exposed to light from below, it is possible to prevent the shape of the end portions of the color filters 10.11 from being disturbed. Therefore, color mixture between adjacent color filters and roughness of the image within the imaging screen can be suppressed. Next, a second protective film 12 made of transparent resin is formed on the color filter 10.11. Effects of the Invention As is clear from the above description, in the color solid-state imaging device of the present invention, the antireflection film is formed in close contact with the light shielding film that covers the transfer electrode. Later, when a color filter is patterned and formed on the flat layer by exposure so as to face the photoelectric conversion section, the light incident on the antireflection film during the exposure can be absorbed by the antireflection film. Therefore, it is possible to suppress the reflection of light during the exposure at the locations of the anti-reflection film and the light-shielding film, and it is possible to suppress the end portions of the color filter from being exposed from below, thereby making it possible to prevent the color filter from being exposed to light from below. Disturbing the shape of the end can be suppressed. therefore,
It is possible to suppress the occurrence of color mixture with adjacent color filters of different colors at the end portions of the color filter and the roughness of the image on the imaging screen. Moreover, the f binary incident on the antireflection film from the end of the color filter is
It is absorbed by the anti-reflection film and can suppress reflection. Therefore, it is possible to suppress the above-mentioned light from being reflected by the above-mentioned anti-reflection film, diffusely reflected by the protective film, flat layer, or color filter, and entering the photoelectric conversion unit, thereby suppressing the imaging screen from becoming unclear. be able to. In the method for manufacturing a color solid-state imaging device of the present invention, the anti-reflection film is formed so as to cover the transfer electrode and adhere closely to the light-shielding film. When patterning and forming a color filter by exposure so as to face the photoelectric conversion section, the light incident on the antireflection film during the exposure can be absorbed by the antireflection film. Therefore, it is possible to suppress the reflection of light during the exposure at the locations of the anti-reflection film and the light-shielding film, and it is possible to suppress the end portions of the color filter from being exposed from below, thereby making it possible to prevent the color filter from being exposed to light from below. Disturbing the shape of the end can be suppressed. Therefore, it is possible to suppress the occurrence of color mixture with adjacent color filters of different colors at the end portions of the color filter and the roughness of the image within the image pickup screen. However, when a metal or alloy with high optical reflectance is used as the material of the light-shielding film, and the anti-reflection film mentioned above is formed by oxidizing the upper surface of the metal or alloy with high optical reflectance, , the above antireflection film can be easily formed.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a color solid-state imaging device according to an embodiment of the present invention, FIG. 2 is a sectional view showing a method for manufacturing a color solid-state imaging device according to an embodiment of the present invention, and FIG. 3 is a sectional view of a conventional color solid-state imaging device. FIG. 2 is a schematic top view of a color solid-state imaging device manufactured by an imaging device manufacturing method. 1...Substrate, 2...Photoelectric conversion section, 3. Charge transfer section, 4...Insulating layer, 5...Transfer electrode, 6...Light shielding film, 7...Anti-reflection film, 8. First Protective film, 9... Flat layer, 10.11... Color filter 12 second protective film, 21... Aρ-9i alloy layer, resist.

Claims (2)

[Claims] (1) A substrate on which photoelectric conversion sections and charge transfer sections are alternately formed; a transfer electrode formed to face the charge transfer section; and a substrate formed on the transfer electrode so as to cover the transfer electrode. a light-shielding film, an anti-reflection film formed in close contact with the light-shielding film, a flat layer formed on the anti-reflection film and on the photoelectric conversion section, and a flat layer on the flat layer facing the photoelectric conversion section. A solid-state imaging device characterized by comprising a color filter formed as shown in FIG. (2) On a substrate on which photoelectric conversion parts and charge transfer parts are formed alternately, a transfer electrode is formed so as to face the charge transfer part, and then on the transfer electrode, a transfer electrode is formed so as to cover the transfer electrode. To,
forming a light-shielding film; next, forming an anti-reflection film in close contact with the light-shielding film; then forming a flat layer on the anti-reflection film and on the photoelectric conversion section; A method for manufacturing a color solid-state imaging device, comprising patterning and forming a color filter on the layer by exposure so as to face the photoelectric conversion section.