JP2006222278A - Solid-state imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state imaging device capable of preventing the generation of the color mixing of an image by preventing the projection of light to a charge storage formed on a semiconductor substrate. <P>SOLUTION: In the solid-state imaging device, a photoelectric converter generating charges is formed on the semiconductor substrate. The device has a transfer line formed on the top face of the semiconductor substrate, a plurality of the charge storages formed on the top face of the semiconductor substrate and storing charges, and reading electrodes formed on the top face of the semiconductor substrate and capable of inducing charges stored in the charge storages to the transfer line. The device further has a contact electrically connecting the charge storages and the photoelectric converter and light-shielding films formed so as to coat the top faces of the reading electrodes. In the device, flanges projected from the contact are formed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a solid-state imaging device that captures a color image.

  Conventionally, single-type color solid-state imaging devices such as CCD and CMOS image sensors mounted on digital cameras and digital video cameras have the same photoelectric conversion elements of millions of pixels and signal readout circuits for reading signals from each pixel. It was the structure formed on a semiconductor substrate. In this case, the area of the light receiving surface of each photoelectric conversion element cannot be increased, the size of the light receiving surface is in the wavelength order of the incident light, the amount of light that can be detected by one pixel is reduced, and the sensitivity is reduced. There was a disadvantage that the yield decreased and the cost increased.

  Therefore, as shown in FIG. 4, in the conventional stacked solid-state imaging device 100, only the signal readout circuit is provided on the semiconductor substrate 110, and the photoelectric conversion film 101 for blue color detection and the green color detection photoelectric conversion film 101 are formed on the upper layer part of the semiconductor substrate 110. A stacked solid-state imaging device having a configuration in which a photoelectric conversion film 102 and a red detection photoelectric conversion film 103 are stacked has been developed (for example, Patent Documents 1, 2, 3, and 4 below).

  The conventional stacked solid-state imaging device 100 converts light received by the photoelectric conversion films 101, 102, and 103 into electrons, and contacts each pixel electrode 104, 105, 106 of the photoelectric conversion films 101, 102, 103. The lead 111 is led to the charge storage units 107, 108, and 109 arranged two-dimensionally on the semiconductor substrate 110. Then, charges are transferred from the charge storage units 107, 108, and 109 to the transfer path 112 formed on the semiconductor substrate under predetermined control by the signal readout circuit, and for each column of the charge storage units 107, 108, and 109. Forwarding.

JP 58-103165 A Japanese Unexamined Patent Publication No. 63-300575 JP 2003-332551 A JP 2003-234460 A

  By the way, when the incident light passes through the upper photoelectric conversion films 101, 102, and 103 and enters the charge storage units 107, 108, and 109, the photoelectric connected to the charge storage units 107, 108, and 109 by the contact unit 111. There is a phenomenon in which electrons representing light of wavelengths corresponding to the conversion films 101, 102, and 103 are generated, and as a result, color mixing occurs in the formed image.

  Conventionally, in order to avoid light from entering the charge storage units 107, 108, and 109, a light shielding film is formed over the semiconductor substrate 110 so as to cover the charge storage units 107, 108, and 109. However, it is necessary to provide the contact portion 111 for connecting the charge storage portions 107, 108, 109 and the photoelectric conversion film in the semiconductor substrate 110, and the light shielding film cannot be formed on the entire upper surface of the semiconductor substrate 110. There is room for improvement in that light may pass between the light shielding films and enter the charge storage portions 107, 108, and 109 to cause color mixing of the image.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a solid that can prevent color mixture of images by preventing light from entering a charge storage portion provided on a semiconductor substrate. An imaging device is provided.

  An object of the present invention is a solid-state imaging device provided with a photoelectric conversion unit that receives light and generates charges above a semiconductor substrate, the transfer path formed on the upper surface of the semiconductor substrate, and the semiconductor A plurality of charge storage portions that are formed on an upper surface of the substrate and store the charge; a readout electrode that is provided on the semiconductor substrate and that can guide the charge stored in the charge storage portion to the transfer path; and the charge storage A columnar contact portion that is electrically connected to the photoelectric conversion portion and extends from the charge storage portion to the photoelectric conversion portion, and a light-shielding film provided to cover the upper surface of the readout electrode, This is achieved by a solid-state imaging device characterized in that a protruding flange portion is formed on the contact portion.

  In the solid-state imaging device of the present invention, a flange portion is provided at a contact portion provided between the photoelectric conversion portion and the charge storage portion in the semiconductor substrate. For this reason, light incident between the light shielding films can be shielded by the flange portion of the contact portion, and even when the light is incident obliquely, the flange portion and the light shielding film are in the vertical direction of the semiconductor substrate. Since they are arranged so as to overlap each other, it is possible to prevent light from passing between the flange portion and the light shielding film. Therefore, it is possible to prevent light from entering the charge storage portion of the semiconductor substrate and prevent color mixing in the formed image without generating electrons in the charge storage portion.

  The solid-state imaging device is preferably provided so that the flange portion overlaps at least a part of the light shielding film with respect to the vertical direction of the semiconductor substrate. In this way, light incident obliquely between the light shielding films can be shielded by the flange portion of the contact portion, and the light can be more reliably prevented from passing between the flange portion and the light shielding film. it can.

  In the solid-state imaging device, it is preferable that an extension portion is provided in the light shielding film, and the extension portion overlaps the flange portion and the vertical direction of the semiconductor substrate. In this case, at least a part of the flange portion and the light shielding film overlap with each other in the vertical direction of the semiconductor substrate, and the extending portion of the light shielding film also overlaps, so that light passes between the light shielding films. It can prevent more reliably that it injects into a charge storage part. Furthermore, it is more preferable that the light shielding film has a portion that sandwiches the flange portion apart from above and below. In this way, it is possible to more reliably prevent light from passing between the light shielding films and entering the charge storage portion.

  In the solid-state imaging device, it is preferable that the flange portion is formed at an end portion of the contact portion that contacts the charge storage portion so as to cover the upper surface of the charge storage portion. In this case, the flange portion and at least a part of the light shielding film overlap with the vertical direction of the semiconductor substrate, and the end portion of the contact portion covers the upper surface of the charge storage portion. And the flange portion formed at the end of the contact portion can be shielded from light, and can be more reliably prevented from entering the charge storage portion.

  ADVANTAGE OF THE INVENTION According to this invention, the solid-state imaging device which can prevent that the color mixing of an image arises by preventing that light injects into the charge storage part provided in the semiconductor substrate can be provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the upper direction and the lower direction refer to the upward direction and the downward direction, respectively, when the drawing is viewed from the front.
First, a first embodiment of a solid-state imaging device according to the present invention will be described. FIG. 1 is a cross-sectional view showing the configuration of the solid-state imaging device of the present embodiment. In the following embodiments, a so-called stacked solid-state imaging device in which photoelectric conversion units are stacked has been described. However, in the configuration of the present application, a photoelectric conversion unit is formed in one layer and incident light in a specific wavelength range is formed. The present invention can also be applied to a so-called hybrid type solid-state imaging device that generates electric charges.

  As shown in FIG. 1, the solid-state imaging device 10 includes a semiconductor substrate and three photoelectric conversion units 21, 22, and 23 stacked above the semiconductor substrate.

  The three photoelectric conversion units 21, 22, and 23 are each a photoelectric conversion film, a light-transmissive pixel electrode film that is two-dimensionally arranged on the surface of the photoelectric conversion film, and that faces the photoelectric conversion film. It has. Each of the photoelectric conversion units 21, 22, and 23 is one of blue, green, and red of incident light, and absorbs light in different wavelength regions, and generates a photoelectric charge in the photoelectric conversion film. is there.

  In the present embodiment, the light in the red wavelength region is absorbed by the lowermost photoelectric conversion unit 21, the light in the green wavelength region is absorbed by the photoelectric conversion unit 22 stacked thereon, and the photoelectric conversion unit in the uppermost layer is absorbed. 23 absorbs light in the blue wavelength region. However, the order of stacking the photoelectric conversion units is not limited to this.

  The semiconductor substrate is roughly composed of an n layer 11 and a p well layer 12 stacked above the n layer 11. In the vicinity of the surface of the p-well layer 12, a plurality of charge storage portions 13 are arranged two-dimensionally in parallel to the surface direction of the semiconductor substrate. The charge storage unit 13 is electrically connected to any one of the three photoelectric conversion units 21, 22, and 23 and has a function of temporarily holding the photocharge generated in the connected photoelectric conversion unit. Yes.

  On the surface of the p well layer 12, a p plus region 14 provided so as to cover the charge accumulation portion 13, a p plus region 15 adjacent to the end portions of the charge accumulation portion 13 and the p plus region 14, and p A plus region 15 and an adjacent n region 16 are formed.

  The n region 16 is arranged in a straight line so as to extend in the depth direction of FIG. 1, and has a configuration capable of transferring charges held in the charge storage unit 13 to a horizontal transfer path (not shown).

  In the semiconductor substrate, the p plus region 14 and the p plus region 15 are separated from the n region 16, and the defect level of the surface portion of the semiconductor substrate is reduced. A silicon oxide film (not shown) is formed on the outermost surface of the semiconductor substrate.

  A readout electrode 18 is provided on the silicon oxide film on the surface of the semiconductor substrate. The readout electrode 18 is located above the n region 16 and is disposed so that a part of the readout electrode 18 reaches the top of the p plus region 15.

  In addition, a light shielding film 19 is provided so as to cover the upper and end portions of the readout electrode 18. The light shielding film 19 has a function of preventing light transmitted through the photoelectric conversion units 21, 22 and 23 from entering the readout electrode 18. Further, the light shielding film 19 is formed so that a part of the portion covering the end portion of the readout electrode 18 reaches above the p plus region 14.

  The read electrode 18 and the light shielding film 19 are embedded in a transparent insulating layer (not shown) formed between the semiconductor substrate and the photoelectric conversion units 21, 22, and 23.

  One of the photoelectric conversion units 21, 22, and 23 and the charge storage unit 13 corresponding to the photoelectric conversion unit are electrically connected by a contact unit 17. The contact portion 17 is wired in a substantially column shape in a direction perpendicular to the semiconductor substrate (up and down direction in FIG. 1). The photoelectric charges generated in the photoelectric conversion units 21, 22, and 23 are carried to the charge storage unit 13 through the contact unit 17 and stored in the charge storage unit 13. At this time, by applying a bias potential to the pixel electrode films of the photoelectric conversion units 21, 22, and 23, the flow of photocharges to the charge storage unit 13 is promoted.

  In the solid-state imaging device 10 of the present embodiment, the contact portion 17 is provided with a flange portion 17a. The flange portion 17a protrudes so as to overlap at least part of the light shielding film 19 with respect to the vertical direction of the semiconductor substrate. That is, when a vertical straight line extending in the vertical direction in FIG. 1 is assumed, when the vertical straight line overlaps with the flange portion 17a, it means that the light shielding film 19 also overlaps.

  In the solid-state imaging device 10, a flange portion 17 a is provided in a contact portion 17 provided between the photoelectric conversion units 21, 22, and 23 and the charge storage portion 13 in the semiconductor substrate, and the flange portion 17 a is perpendicular to the semiconductor substrate. And is provided so as to overlap at least a part of the light shielding film 19. Therefore, the light incident between the light shielding films 19 can be shielded by the flange portion 17a of the contact portion 17, and the flange portion is perpendicular to the vertical direction of the semiconductor substrate even when the light is incident obliquely. Since the 17a and the light shielding film 19 are arranged so as to overlap each other, it is possible to prevent light from passing between the flange portion 17a and the light shielding film 19. Therefore, by preventing light from entering the charge storage portion 13 of the semiconductor substrate, electrons are not generated in the charge storage portion 13 and color mixing can be prevented from occurring in the image.

  Next, a second embodiment according to the present invention will be described. In the embodiments described below, members having the same configuration / action as those already described are denoted by the same or corresponding reference numerals in the drawings, and description thereof is simplified or omitted.

  FIG. 2 is a cross-sectional view illustrating a configuration of the solid-state imaging device of the present embodiment. As shown in FIG. 2, the solid-state imaging device 20 of the present embodiment is different from the configuration of the first embodiment in that an extending portion 29 a is provided in a part of the light shielding film 29.

  The extending portion 29a is provided so as to overlap the flange portion 17a of the contact portion 17 with respect to the vertical direction (vertical direction in FIG. 2) of the semiconductor substrate.

  Since the solid-state imaging device 20 has a configuration in which at least a part of the flange portion 17a and the light shielding film 29 overlap with each other in the vertical direction of the semiconductor substrate, and the extended portion 29a of the light shielding film 29 also overlaps, incident light is shielded from these. It is possible to more reliably prevent the film 29 from passing through and entering the charge storage unit 13.

Next, a third embodiment according to the present invention will be described. FIG. 3 is a cross-sectional view illustrating a configuration of the solid-state imaging device of the present embodiment.
As shown in FIG. 3, in the solid-state imaging device 30 of the present embodiment, a flange portion 27 a is provided at the end portion of the contact portion 27 on the charge storage portion 13 side so as to cover the upper surface of the charge storage portion 13. Yes.

  The flange portion 27a is preferably formed so as to overlap at least a part of the light shielding film 19 with respect to the vertical direction of the semiconductor substrate.

  The solid-state imaging device 30 of the present embodiment has a configuration in which the flange portion 27a and at least a part of the light shielding film 19 overlap with each other in the vertical direction of the semiconductor substrate, and the end portion of the contact portion 27 covers the upper surface of the charge storage portion 13. Therefore, the incident light can be shielded by the light shielding film 19 and the flange portion 27a formed at the end portion of the contact portion 27, and the incident light can be more reliably prevented from entering. be able to.

In addition, this invention is not limited to embodiment mentioned above, A suitable deformation | transformation, improvement, etc. are possible.
For example, the configuration in which the flange portion 27a is provided at the end of the contact portion 27 on the charge storage portion 13 side in FIG. 3 may be applied to the configuration in FIGS.

It is sectional drawing which shows the structure of the solid-state imaging device of 1st Embodiment. It is sectional drawing which shows the structure of the solid-state imaging device of 2nd Embodiment. It is sectional drawing which shows the structure of the solid-state imaging device of 3rd Embodiment. It is a figure explaining the structure of the conventional laminated | stacked solid-state imaging device.

Explanation of symbols

10, 20, 30 Solid-state imaging device 11 n layer 12 p well layer 13 charge storage portion 14 p plus region 15 p plus region 16 transfer path 17, 27 contact portion 17a, 27a flange portion 18 readout electrode 19, 29 light shielding film 29a extension Installation part 21, 22, 23 Photoelectric conversion part

Claims (6)

A solid-state imaging device provided with a photoelectric conversion unit that receives light and generates charges above a semiconductor substrate,
A transfer path formed on the upper surface of the semiconductor substrate;
A plurality of charge storage portions that are formed on an upper surface of the semiconductor substrate and store the charge;
A readout electrode provided on the semiconductor substrate and capable of guiding the charge accumulated in the charge accumulation portion to the transfer path;
A columnar contact portion that is electrically connected to the charge storage portion and the photoelectric conversion portion and extends from the charge storage portion to the photoelectric conversion portion;
A light shielding film provided so as to cover the upper surface of the readout electrode,
A solid-state image pickup device characterized in that a protruding flange portion is formed on the contact portion.   The solid-state imaging device according to claim 1, wherein the flange portion protrudes so as to overlap at least a part of the light shielding film with respect to a vertical direction of the semiconductor substrate.   3. The solid-state imaging device according to claim 1, wherein an extension portion is provided in the light shielding film, and the extension portion overlaps the flange portion and a vertical direction of the semiconductor substrate.   The solid-state imaging device according to any one of claims 1 to 3, wherein the light shielding film has a portion that sandwiches the flange portion apart from above and below.   3. The solid-state imaging according to claim 1, wherein the flange portion is formed at an end portion of the contact portion in contact with the charge accumulation portion so as to cover an upper surface of the charge accumulation portion. apparatus.   6. The solid-state imaging device according to claim 1, wherein a plurality of the photoelectric conversion units are stacked above the semiconductor substrate.

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