CN116130498A - Image sensor and manufacturing method thereof - Google Patents

Image sensor and manufacturing method thereof Download PDF

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Publication number
CN116130498A
CN116130498A CN202211703032.9A CN202211703032A CN116130498A CN 116130498 A CN116130498 A CN 116130498A CN 202211703032 A CN202211703032 A CN 202211703032A CN 116130498 A CN116130498 A CN 116130498A
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sub
type
pixel
pixels
photo
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赵庆贺
范春晖
李岩
夏小峰
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Hefei Haitu Microelectronics Co ltd
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Hefei Haitu Microelectronics Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14609—Pixel-elements with integrated switching, control, storage or amplification elements
    • H01L27/14612—Pixel-elements with integrated switching, control, storage or amplification elements involving a transistor
    • H01L27/14614—Pixel-elements with integrated switching, control, storage or amplification elements involving a transistor having a special gate structure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/1463—Pixel isolation structures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14632—Wafer-level processed structures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14683—Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof
    • H01L27/14687—Wafer level processing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14683—Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof
    • H01L27/14689—MOS based technologies

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Electromagnetism (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Solid State Image Pick-Up Elements (AREA)

Abstract

The present invention provides an image sensor and a method of manufacturing the same, the image sensor including pixel units each including at least three types of sub-pixels, and the image sensor including at least: a substrate; an isolation layer disposed in the substrate, the isolation layer dividing the substrate into a plurality of light absorbing layers; the photoelectric sensing areas are arranged in the light absorption layers, and in each type of sub-pixels, at least one layer of the light absorption layers is provided with the photoelectric sensing areas, and the positions of the photoelectric sensing areas are different; and a vertical gate disposed on the substrate, the vertical gate being located in each type of sub-pixel and extending into the light absorbing layer of the lowermost layer. The image sensor provided by the invention can improve the pixel quality of the image sensor.

Description

Image sensor and manufacturing method thereof
Technical Field
The invention belongs to the technical field of semiconductor devices, and particularly relates to an image sensor and a manufacturing method thereof.
Background
The image sensor is a device for converting an optical signal into an electrical signal, and is widely used in fields such as photography and security systems, smart phones, facsimile machines, scanners, and medical electronics.
On an image sensor, the identification of different colors of light is achieved by providing color filters in combination with pixel devices. The structure is complex and the manufacturing cost is high. And the use of color filters as filtering materials can also cause crosstalk between pixels, affecting pixel quality.
Disclosure of Invention
The invention aims to provide an image sensor and a manufacturing method thereof, which can save a filtering process, reduce crosstalk between pixels and further improve the pixel quality of the image sensor.
To achieve the above object, the present invention provides an image sensor including pixel units each including at least three types of sub-pixels, including at least:
a substrate;
an isolation layer disposed in the substrate, the isolation layer dividing the substrate into a plurality of light absorbing layers;
the photoelectric sensing areas are arranged in the light absorption layers, and in each type of sub-pixels, at least one layer of the light absorption layers is provided with the photoelectric sensing areas, and the positions of the photoelectric sensing areas are different; and
and the vertical grid is arranged on the substrate, is positioned in each type of sub-pixel, and extends into the light absorption layer at the bottommost layer.
In one embodiment of the present invention, two isolation layers are provided in the image sensor, and the substrate is divided into a first light absorption layer, a second light absorption layer, and a third light absorption layer.
In an embodiment of the present invention, the pixel unit includes a first type of sub-pixel, a second type of sub-pixel, and a third type of sub-pixel.
In an embodiment of the present invention, in each of the sub-pixels, the photoelectric reaction area is disposed in one of the light absorbing layers, and in each of the sub-pixels, the position of the photoelectric reaction area is different.
In an embodiment of the present invention, in the first type of sub-pixel, one of the light absorbing layers is provided with the photoelectric reaction region; the photoelectric reaction areas are arranged in two layers of the light absorption layers of the second type of sub-pixels, and the positions of one photoelectric reaction area and the position of the photoelectric reaction area in the first type of sub-pixels are the same; in the third type of sub-pixel, the photoelectric reaction area is arranged in the three light absorption layers.
In an embodiment of the present invention, in the first type of sub-pixel, one of the light absorbing layers is provided with the photoelectric reaction region; in the second type of sub-pixels, one layer of the light absorption layer is provided with the photoelectric reaction area, wherein the positions of the photoelectric reaction area in the second type of sub-pixels are different from those of the photoelectric reaction area in the first type of sub-pixels; in the third type of sub-pixel, the photoelectric reaction area is arranged in the three light absorption layers.
In an embodiment of the present invention, in the first type of sub-pixel, the photoelectric reaction area is disposed in two layers of the light absorbing layer; in the second type of sub-pixels, two layers of the light absorption layers are provided with the photoelectric reaction areas, wherein one of the photoelectric reaction areas in the second type of sub-pixels is the same as one of the photoelectric reaction areas in the first type of sub-pixels, and the other of the photoelectric reaction areas in the second type of sub-pixels is different from the other of the photoelectric reaction areas in the first type of sub-pixels; in the third type of sub-pixel, photoelectric reaction areas are arranged in the three light absorption layers.
In an embodiment of the present invention, in the first type of sub-pixel, two layers of light are provided with a photoelectric reaction region in the absorption layer; the photoelectric reaction areas are arranged in two layers of the light absorption layers of the second type of sub-pixels, wherein one photoelectric reaction area in the second type of sub-pixels is the same as one photoelectric reaction area in the first type of sub-pixels, and the other photoelectric reaction area in the second type of sub-pixels is different from the other photoelectric reaction area in the first type of sub-pixels; in the third type of sub-pixels, two layers of the light absorption layers are provided with the photoelectric reaction areas, wherein one photoelectric reaction area in the third type of sub-pixels is positioned at the same position as one photoelectric reaction area in the first type of sub-pixels, but is positioned at a different position from two photoelectric reaction areas in the second type of sub-pixels; the other one of the photo-reactive regions in the third type of sub-pixel is at the same location as one of the photo-reactive regions in the second type of sub-pixel, but at a different location from the two photo-reactive regions in the first type of sub-pixel.
In an embodiment of the present invention, an area of the photo sensing region in the first light absorbing layer is smaller than an area of the photo sensing region in the second light absorbing layer and the third light absorbing layer.
The present invention also provides a method of manufacturing an image sensor including pixel units each including at least three types of sub-pixels, the method including the steps of:
providing a substrate;
forming an isolation layer in the substrate, dividing the substrate into a plurality of light absorbing layers;
forming a photoelectric sensing region in the light absorption layer, wherein the photoelectric sensing region is arranged in at least one layer of the light absorption layer in each type of sub-pixels, and the positions of the photoelectric sensing regions are different in each type of sub-pixels; and
vertical gates are formed on the substrate, located in each type of sub-pixel, and extending into the light absorbing layer of the bottommost layer.
In summary, the image sensor provided by the invention utilizes the photo-sensing regions with different depths matched with the vertical gate to realize light absorption with different wavelengths, thereby saving the filtering process. Isolation layers are adopted between different absorption depths to isolate signals, so that signal crosstalk is prevented. And the sub-pixels with different absorption depths are used for combining the pixel units to output the graphic information. The vertical grid can further reduce the area of the image sensor and increase the integration level.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a 4T circuit configuration diagram of an image sensor according to the present invention.
Fig. 2 is a schematic view showing the distribution of the photoelectric reaction regions in a pixel unit in which only one light absorbing layer in each sub-pixel is provided with the photoelectric reaction regions in the present invention.
Fig. 3 is a schematic diagram of the first type of sub-pixel in fig. 2 according to the present invention.
FIG. 4 is a schematic diagram of a second type of sub-pixel in FIG. 2 according to the present invention.
Fig. 5 is a schematic structural diagram of a third type of sub-pixel in fig. 2 according to the present invention.
Fig. 6 is a schematic diagram of the distribution of the photoelectric reaction regions in the pixel unit in which one, two and three photoelectric reaction regions are respectively disposed in each sub-pixel.
Fig. 7 is a schematic diagram of the first type of sub-pixel in fig. 6 according to the present invention.
FIG. 8 is a schematic diagram of a second type of sub-pixel in FIG. 6 according to the present invention.
Fig. 9 is a schematic diagram of a third type of sub-pixel in fig. 6 according to the present invention.
Fig. 10 is a schematic diagram showing the distribution of the photoelectric reaction regions in a pixel unit in which one layer, one layer and three light absorbing layers are respectively disposed in each sub-pixel.
Fig. 11 is a schematic diagram of a first type of sub-pixel in fig. 10 according to the present invention.
FIG. 12 is a schematic diagram of a second type of sub-pixel in FIG. 10 according to the present invention.
Fig. 13 is a schematic diagram of a third type of sub-pixel in fig. 10 according to the present invention.
Fig. 14 is a schematic view showing the distribution of the photoelectric reaction regions in a pixel unit in which two layers, two layers and three layers of light absorbing layers are respectively disposed in each sub-pixel.
Fig. 15 is a schematic view showing the structure of the first type of sub-pixel in fig. 14 according to the present invention.
FIG. 16 is a schematic diagram of a second type of sub-pixel in FIG. 14 according to the present invention.
Fig. 17 is a schematic diagram of the third type of sub-pixel in fig. 14 according to the present invention.
Fig. 18 is a schematic view showing the distribution of the photoelectric reaction regions in the pixel unit in which two layers of the photoelectric reaction regions are respectively disposed in each sub-pixel, and two layers of the photoelectric reaction regions are disposed in each sub-pixel.
Fig. 19 is a schematic view showing the structure of a first type of sub-pixel in fig. 18 according to the present invention.
FIG. 20 is a schematic diagram of a second type of sub-pixel in FIG. 18 according to the present invention.
Fig. 21 is a schematic diagram of a third type of sub-pixel in fig. 18 according to the present invention.
Fig. 22 is a schematic view of a structure of forming an isolation layer in a substrate in the present invention.
Fig. 23 is a schematic view of a structure of forming a photo-sensing region in a substrate in the present invention.
Fig. 24 is a schematic view of a structure of forming a groove in a substrate in the present invention.
Fig. 25 is a schematic view of a structure in which a gate oxide layer is formed in a substrate in the present invention.
Fig. 26 is a schematic view of a structure of forming a polysilicon layer in a substrate in the present invention.
Fig. 27 is a schematic view of a structure of forming vertical gates in a substrate in the present invention.
Detailed Description
In order to facilitate an understanding of the present application, a more complete description of the present application will now be provided with reference to the relevant figures. Preferred embodiments of the present application are shown in the accompanying drawings. This application may, however, be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
In the description of the present invention, it should be understood that the directions or positional relationships indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the apparatus or component to be referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
Referring to fig. 1, in an image sensor, a pixel array is provided. The image sensor comprises a pixel array, a plurality of photodiodes PD arranged in an array, wherein each photodiode PD forms a pixel point, the plurality of photodiodes PD form the pixel array, a scene is focused on the pixel array of the image sensor through an imaging lens, and the photodiodes PD can convert the light intensity of the surface into electric signals and store the electric signals. The pixel array further includes a plurality of transistors including, for example, a transfer transistor VTG, a reset transistor RX, a source follower SF, and a row select transistor SEL. The connection relationship among the transfer transistor VTG, the reset transistor RX, the source follower SF, and the row select transistor SEL is shown in fig. 1. The transfer transistor VTG transfers electrons generated by the photodiode PD to the floating diffusion region. The source follower SF may play an amplifying role. When photoelectric conversion is carried out, signal acquisition and reading are completed by adopting the time sequence of correlated double sampling.
As shown in fig. 1, in a pixel array on an image sensor, with one photodiode PD as one sub-pixel, at least three sub-pixels of three primary colors can be read to form one pixel unit. In the image sensor provided with the color filters, after ambient light passes through the mirror and the color filters with three primary colors, responses of the three primary colors of red, green and blue are respectively acquired, and after the responses are output through different sub-pixels, the responses are further fitted into image output.
As shown in fig. 2 to 5, the present application provides an image sensor, in which a plurality of photo-sensing regions 105 with different depths are disposed in a substrate 101, and a plurality of sub-pixels having the photo-sensing regions 105 with different depths are formed. Since the photo-sensing regions 105 with different depths absorb wavelengths of different colors, a pixel unit can be formed by forming sub-pixels with the photo-sensing regions 105 with different depths, so as to output image information.
As shown in fig. 2 to 5, in an embodiment of the present application, the substrate 101 may be any suitable semiconductor material, for example, a substrate such as silicon carbide (SiC), gallium nitride (GaN), aluminum nitride (AlN), indium nitride (InN), silicon germanium (GeSi), sapphire or silicon wafer, and the stack structure formed by these semiconductors, or be silicon on insulator, silicon germanium on insulator, and germanium on insulator, which may be specifically selected according to the manufacturing requirements of the image sensor. In the present embodiment, the substrate 101 is, for example, a silicon substrate, and is a doped substrate.
As shown in fig. 2 to 5, in an embodiment of the present application, a plurality of pixel units are provided on an image sensor. And a plurality of sub-pixels are disposed in one pixel unit. Wherein one pixel unit comprises at least e.g. 3 sub-pixels. In this embodiment, one pixel unit includes, for example, 4 sub-pixels, and the 4 word pixels are arranged in a square, i.e., are combined into one pixel unit according to a conventional bayer array. Wherein the two sub-pixels have the same structure, and the two sub-pixels with the same structure are positioned at the diagonal positions. That is, in the present embodiment, one pixel unit includes three types of sub-pixels, and is defined as a first type sub-pixel 1001, a second type sub-pixel 1002, and a third type sub-pixel 1003. Wherein, one pixel unit includes two second type sub-pixels 1002, and the two second type sub-pixels 1002 are located at diagonal positions.
As shown in fig. 2 to 5, in an embodiment of the present application, in the substrate 101 where each sub-pixel is located, a layer isolation layer 102 is provided, and the layer isolation layer 102 is provided at positions of different depths of the substrate 101 to divide the substrate 101 into a plurality of light absorbing layers. In this application, for example, two isolation layers 102 are provided in the substrate 101, dividing the substrate 101 into, for example, three light absorbing layers. Wherein one isolation layer 102 is located at a depth of, for example, 250nm to 350nm from the surface of the substrate 101 and the other isolation layer 102 is located at a depth of, for example, 2000nm to 2500nm from the surface of the substrate 101. The two-layer separation layer 102 separates the substrate 101 into a first light absorbing layer 1031, a second light absorbing layer 1032, and a third light absorbing layer 1033, wherein the first light absorbing layer 1031 has a depth less than the second light absorbing layer 1032 and a depth less than the third light absorbing layer 1033. Specifically, the depth of the first light absorbing layer 1031 is smaller than, for example, 300nm, the depth of the second light absorbing layer 1032 is larger than, for example, 300nm, and smaller than, for example, 2500nm, and the depth of the third light absorbing layer 1033 is larger than, for example, 2500nm. The first light-absorbing layer 1031 is a blue light-absorbing layer, the second light-absorbing layer 1032 is a green light-absorbing layer, and the third light-absorbing layer 1033 is a red light-absorbing layer.
As shown in fig. 2 to 5, the specific thickness of each isolation layer 102 is not limited in the present application, and in this embodiment, the thickness of the isolation layer 102 is, for example, 50nm to 100nm. In forming the isolation layer 102, P-type ions or oxygen ions may be implanted into the substrate 101 to form the isolation layer 102. The P-type ion is, for example, a boron ion (B).
As shown in fig. 2 to 5, in the present application, the photo-sensing region 105 is provided in the light absorbing layer. In this embodiment, the photo-sensing region 105 is formed, for example, by implanting N-type ions into the substrate 101. In this application, in each type of sub-pixel, at least one light absorbing layer is provided with a photo-sensing region 105, and in each type of sub-pixel, the position of the photo-sensing region 105 is different.
As shown in fig. 2 to 5, in each type of sub-pixel, a vertical gate 104 is further disposed on the substrate 101, and the vertical gate 104 is located on the surface of the substrate 101 and extends into the bottommost light absorbing layer. Wherein the depth of the vertical gate 104 is greater than, for example, 3um. Specifically, the substrate 101 is etched in each sub-pixel to form a recess having a depth reaching the third light absorption layer 1033. Next, silicon oxide is formed on the sidewall of the recess and the surface of the substrate 101 by a furnace tube thermal oxidation process, and a gate oxide layer 107 is formed. Finally, polysilicon is deposited in the grooves and on the surface of the substrate 101, and the polysilicon on the surface of the substrate 101 is etched to form vertical gates 104. The vertical gate 104 corresponds to the transfer transistor VTG in fig. 1, and the vertical gate 104 extending to the third light absorbing layer 1033 may have three responses in series.
As shown in fig. 2 to 5, in an embodiment of the present application, in each type of sub-pixel, a photo-sensing region 105 is disposed in one light absorbing layer, and in each type of sub-pixel, the photo-sensing region 105 is located differently. Specifically, in the present embodiment, in the first type subpixel 1001, the photo-sensing region 105 is disposed in the first light absorbing layer 1031. In the second type of sub-pixel 1002, the photo-sensing region 105 is disposed in the second light absorbing layer 1032. In the third type of sub-pixel 1003, the photo-sensing region 105 is disposed in the third light absorbing layer 1033. At this time, a blue light signal, a green light signal, and a red light signal of a single color may be directly output.
As shown in fig. 6 to 9, in another embodiment of the present application, in the first type subpixel 1001, a light absorbing layer is provided with a light sensing region 105. In the second type of sub-pixel 1002, the photo-sensing regions 105 are disposed in two light absorbing layers, wherein one photo-sensing region 105 is located at the same position as the photo-sensing region 105 in the first type of sub-pixel 1001. In the third type of sub-pixel 1003, the photo-sensing region 105 is disposed in each of the three light absorbing layers. Specifically, in the present embodiment, in the first type subpixel 1001, the photo-sensing region 105 is disposed in the first light absorbing layer 1031. In the second type of sub-pixel 1002, the photo-sensing region 105 is disposed in the first light absorbing layer 1031, and the second light absorbing layer 1032 or the third light absorbing layer 1033. In the third type of sub-pixel 1003, the photo-sensing region 105 is disposed in the first, second, and third light absorbing layers 1031, 1032, 1033. In a further embodiment of the present application, the photo-sensing region 105 is disposed in the second light absorbing layer 1032 in the first type of sub-pixel 1001 on the basis of fig. 6 to 9. In the second type of sub-pixel 1002, the photo-sensing region 105 is disposed in the second light absorbing layer 1032, and either the first light absorbing layer 1031 or the third light absorbing layer 1033. In the third type of sub-pixel 1003, the photo-sensing region 105 is disposed in the first, second, and third light absorbing layers 1031, 1032, 1033. In a further embodiment of the present application, the photo-sensing region 105 is disposed in the third light absorbing layer 1033 in the first type of sub-pixel 1001 on the basis of fig. 6 to 9. In the second type of sub-pixel 1002, the photo-sensing region 105 is disposed in the third light absorbing layer 1033, and either the first light absorbing layer 1031 or the second light absorbing layer 1032. In the third type of sub-pixel 1003, the photo-sensing region 105 is disposed in the first, second, and third light absorbing layers 1031, 1032, 1033. At this time, when each type of optical signal is acquired, a signal output by the first type subpixel 1001 is used as one type of optical signal. The signal output by the first type subpixel 1001 is subtracted from the signal output by the second type subpixel 1002 as another type of optical signal. The signal output by the second type of sub-pixel 1002 is subtracted from the signal output by the third type of sub-pixel 1003 as a further type of optical signal. Three types of optical signals can be obtained.
As shown in fig. 10 to 13, in another embodiment of the present application, in the first type subpixel 1001, a photo-sensing region 105 is disposed in a light absorbing layer. In the second type of sub-pixel 1002, a photo-sensing region 105 is disposed in a light absorbing layer, wherein the photo-sensing region 105 in the second type of sub-pixel 1002 is located at a different position than the photo-sensing region 105 in the first type of sub-pixel 1001. In the third type of sub-pixel 1003, the photo-sensing region 105 is disposed in each of the three light absorbing layers. Specifically, in the present embodiment, in the first type subpixel 1001, the photo-sensing region 105 is disposed in the first light absorbing layer 1031. In the second type of sub-pixel 1002, the photo-sensing region 105 is disposed in the second light absorbing layer 1032. In the third type of sub-pixel 1003, the photo-sensing region 105 is disposed in the first, second, and third light absorbing layers 1031, 1032, 1033. In a further embodiment, based on fig. 10 to 13, in the first type of sub-pixel 1001, the photo-sensing region 105 is disposed in the first light absorbing layer 1031. In the second type of sub-pixel 1002, the photo-sensing region 105 is disposed in the third light absorbing layer 1033. In the third type of sub-pixel 1003, the photo-sensing region 105 is disposed in the first, second, and third light absorbing layers 1031, 1032, 1033. In a further embodiment, based on fig. 10 to 13, in the first type of sub-pixel 1001, the photo-sensing region 105 is disposed in the second light absorbing layer 1032. In the second type of sub-pixel 1002, the photo-sensing region 105 is disposed in the third light absorbing layer 1033. In the third type of sub-pixel 1003, the photo-sensing region 105 is disposed in the first, second, and third light absorbing layers 1031, 1032, 1033. At this time, when each type of optical signal is acquired, a signal output by the first type subpixel 1001 is used as one type of optical signal. The signal output by the second type of sub-pixel 1002 is used as another type of optical signal. The signal output by the first type subpixel 1001 and the signal output by the second type subpixel 1002 are subtracted from the signal output by the third type subpixel 1003 as a further type of optical signal. Three types of optical signals can be obtained.
As shown in fig. 14 to 17, in another embodiment of the present application, in the first type subpixel 1001, a photo-sensing region 105 is provided in two light absorbing layers. In the second type of sub-pixel 1002, the photo-sensing regions 105 are disposed in two light absorbing layers, wherein one photo-sensing region 105 in the second type of sub-pixel 1002 is located at the same position as one photo-sensing region 105 in the first type of sub-pixel 1001, and the other photo-sensing region 105 in the second type of sub-pixel 1002 is located at a different position from the other photo-sensing region 105 in the first type of sub-pixel 1001. In the third type of sub-pixel 1003, the photo-sensing region 105 is disposed in each of the three light absorbing layers. Specifically, in the present embodiment, in the first type subpixel 1001, the photo-sensing region 105 is disposed in the first light absorbing layer 1031 and the second light absorbing layer 1032. In the second type of sub-pixel 1002, the photo-sensing region 105 is disposed in the second light absorbing layer 1032 and the third light absorbing layer 1033. In the third type of sub-pixel 1003, the photo-sensing region 105 is disposed in the first, second, and third light absorbing layers 1031, 1032, 1033. As in fig. 14 to 17, in still another embodiment, in the first type subpixel 1001, the photo-sensing region 105 is disposed in the first light absorbing layer 1031 and the third light absorbing layer 1033. In the second type of sub-pixel 1002, the photo-sensing region 105 is disposed in the second light absorbing layer 1032 and the third light absorbing layer 1033. In the third type of sub-pixel 1003, the photo-sensing region 105 is disposed in the first, second, and third light absorbing layers 1031, 1032, 1033. At this time, when each type of optical signal is acquired, the signal output by the first type of subpixel 1001 is subtracted from the signal output by the third type of subpixel 1003 as one type of optical signal. The signal output by the second type of sub-pixel 1002 is subtracted from the signal output by the third type of sub-pixel 1003 as another type of optical signal. The signal output by the third sub-pixel is subtracted from the sum of the signal output by the first type sub-pixel 1001 and the signal output by the second type sub-pixel 1002, and the result is divided by two as a further type of optical signal. Three types of optical signals can be obtained.
As shown in fig. 18 to 21, in another embodiment of the present application, in the first type subpixel 1001, a photo-sensing region 105 is provided in two light absorbing layers. In the second type of sub-pixel 1002, the photo-sensing regions 105 are disposed in two light absorbing layers, wherein one photo-sensing region 105 in the second type of sub-pixel 1002 is located at the same position as one photo-sensing region 105 in the first type of sub-pixel 1001, and the other photo-sensing region 105 in the second type of sub-pixel 1002 is located at a different position from the other photo-sensing region 105 in the first type of sub-pixel 1001. In the third type of sub-pixel 1003, two photo-sensing regions 105 are disposed in the light absorbing layer, wherein one photo-sensing region 105 in the third type of sub-pixel 1003 is located at the same position as one photo-sensing region 105 in the first type of sub-pixel 1001, but is located at a different position from two photo-sensing regions 105 in the second type of sub-pixel 1002; the other photo-sensing region 105 in the third type of sub-pixel 1003 is located at the same position as one photo-sensing region 105 in the second type of sub-pixel 1002, but at a different position than two photo-sensing regions 105 in the first type of sub-pixel 1001. Specifically, in the present embodiment, in the first type subpixel 1001, the photo-sensing region 105 is disposed in the first light absorbing layer 1031 and the second light absorbing layer 1032. In the second type of sub-pixel 1002, the photo-sensing region 105 is disposed in the second light absorbing layer 1032 and the third light absorbing layer 1033. In the third type of sub-pixel 1003, the photo-sensing region 105 is disposed in the first light absorbing layer 1031 and the third light absorbing layer 1033. At this time, when each type of optical signal is acquired, the signal output by the third sub-pixel is subtracted from the sum of the signal output by the first-type sub-pixel 1001 and the signal output by the second-type sub-pixel 1002, and the result is divided by two as one type of optical signal. The signal output by the first sub-pixel is subtracted from the sum of the signal output by the second type sub-pixel 1002 and the signal output by the third type sub-pixel 1003, and the result is divided by two as another type of optical signal. The signal output by the second sub-pixel is subtracted from the sum of the signal output by the first sub-pixel 1001 and the signal output by the third sub-pixel 1003, and the result is divided by two as a further type of optical signal. Three types of optical signals can be obtained.
As shown in fig. 2 to 21, in the present application, in the first light absorbing layer 1031, a floating diffusion region 106 is also provided. A floating diffusion region 106 is located in the substrate 101 near the surface of the substrate 101 for storing electrons generated by photoelectric conversion. To avoid the floating diffusion region 106 from contacting the photo-sensing region 105 in the first light absorbing layer 1031, the area of the photo-sensing region 105 in the first light absorbing layer 1031 is smaller than the areas of the photo-sensing regions 105 in the second and third light absorbing layers 1032 and 1033. In outputting the signal in the first light absorbing layer 1031, algorithm optimization may be performed according to the area ratio of the first light absorbing layer 1031 and the third light absorbing layer 1033. The signal of the first light absorbing layer 1031 is amplified in the same proportion to increase the true saturation of the color.
In the application, the photosensitive principle of the silicon material is that photons can penetrate a certain depth and then be absorbed by silicon atoms after entering the surface of the silicon material. If the energy of the photon is greater than the forbidden bandwidth of silicon (1.12 ev corresponds to 1100nm wavelength), an electron and hole pair can be excited, where silicon has an absorption coefficient a at each wavelength that decreases with increasing wavelength, i.e. short wavelength photons are easily absorbed at the surface and long wavelength photons are easily absorbed at deeper locations. According to the arrangement of the isolation layers, a plurality of light absorption layers are formed, and light with different wavelengths can be absorbed.
As shown in fig. 22 to 27, in the present application, at the time of forming an image sensor, the forming process is as shown in fig. 22 to 27. First, as shown in fig. 22, a substrate 101 is provided, and P-type ions or oxygen ions are implanted into the substrate 101 to form an isolation layer 102. Wherein the isolation layer 102 separates the substrate 101 into multiple light absorbing layers, including, for example, a first light absorbing layer 1031, a second light absorbing layer 1032, and a third light absorbing layer 1033. Next, as shown in fig. 23, N-type ions are implanted into the light absorbing layer to form a photo sensor region 105. The position of the photo-sensing region 105 is set according to the sub-pixel to be formed. The photo-sensing region 105 may be disposed in the first light absorbing layer 1031, may be disposed in the second light absorbing layer 1032, or may be disposed in two or three of the first light absorbing layer 1031, the second light absorbing layer 1032, and the second light absorbing layer 1032. In this embodiment, the photo-sensing region 105 is disposed in the second light absorbing layer 1032. After the formation of the photo-sensing region 105, the substrate 101 is etched to form a recess, as shown in fig. 24. The grooves may extend into the bottommost light absorbing layer. In etching the substrate 101, a layer of silicon nitride may be deposited on the surface of the substrate 101 as an etch stop layer to protect the surface of the substrate 101. After forming the recess, the etch stop layer may be removed. After forming the recess, a furnace tube thermal oxidation process is used to form silicon oxide on the recess sidewalls of the surface area of the substrate 101, thereby forming the gate oxide layer 107, as shown in fig. 25. As shown in fig. 26, after forming the gate oxide layer 107, a polysilicon layer 1041 is deposited in the recess and on the surface of the substrate 101. And as shown in fig. 27, the polysilicon layer 1041 on the substrate 101 is etched as required to form a vertical gate 104.
In summary, the present invention provides an image sensor and a method for manufacturing the same, the image sensor includes pixel units, each of which includes at least three types of sub-pixels. And the image sensor further comprises a substrate. An isolation layer disposed in the substrate, the isolation layer dividing the substrate into a plurality of light absorbing layers. The photoelectric sensing areas are arranged in the light absorption layers, and in each type of sub-pixels, the photoelectric sensing areas are arranged in at least one layer of light absorption layer, and in each type of sub-pixels, the positions of the photoelectric sensing areas are different. By arranging the photoelectric sensing areas with different depths, light with different wavelengths is absorbed and isolated by the isolating layer. A vertical gate is also provided in the substrate, the vertical gate being located in each type of sub-pixel and extending into the bottommost light absorbing layer, so as to direct out the light signal.
The embodiments of the invention disclosed above are intended only to help illustrate the invention. The examples are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best understand and utilize the invention. The invention is limited only by the claims and the full scope and equivalents thereof.

Claims (10)

1. An image sensor, comprising pixel cells, each of the pixel cells comprising at least three types of sub-pixels, the image sensor comprising at least:
a substrate;
an isolation layer disposed in the substrate, the isolation layer dividing the substrate into a plurality of light absorbing layers;
the photoelectric sensing areas are arranged in the light absorption layers, and in each type of sub-pixels, at least one layer of the light absorption layers is provided with the photoelectric sensing areas, and the positions of the photoelectric sensing areas are different; and
and the vertical grid is arranged on the substrate, is positioned in each type of sub-pixel, and extends into the light absorption layer at the bottommost layer.
2. An image sensor according to claim 1, wherein two of said isolation layers are provided in said image sensor, dividing said substrate into a first light absorbing layer, a second light absorbing layer and a third light absorbing layer.
3. An image sensor according to claim 2, wherein the pixel unit comprises a first type of sub-pixel, a second type of sub-pixel and a third type of sub-pixel.
4. An image sensor according to claim 3, wherein in each of said sub-pixels, said photo-reactive region is provided in one of said light absorbing layers, and the position of said photo-reactive region is different in each of said sub-pixels.
5. An image sensor according to claim 3, wherein in said first type of sub-pixel, one of said light absorbing layers has said photo-reactive region disposed therein; the photoelectric reaction areas are arranged in two layers of the light absorption layers of the second type of sub-pixels, and the positions of one photoelectric reaction area and the position of the photoelectric reaction area in the first type of sub-pixels are the same; in the third type of sub-pixel, the photoelectric reaction area is arranged in the three light absorption layers.
6. An image sensor according to claim 3, wherein in said first type of sub-pixel, one of said light absorbing layers has said photo-reactive region disposed therein; in the second type of sub-pixels, one layer of the light absorption layer is provided with the photoelectric reaction area, wherein the positions of the photoelectric reaction area in the second type of sub-pixels are different from those of the photoelectric reaction area in the first type of sub-pixels; in the third type of sub-pixel, the photoelectric reaction area is arranged in the three light absorption layers.
7. An image sensor according to claim 3, wherein in said first type of sub-pixel, two of said light absorbing layers are provided with said photo-reactive regions; in the second type of sub-pixels, two layers of the light absorption layers are provided with the photoelectric reaction areas, wherein one of the photoelectric reaction areas in the second type of sub-pixels is the same as one of the photoelectric reaction areas in the first type of sub-pixels, and the other of the photoelectric reaction areas in the second type of sub-pixels is different from the other of the photoelectric reaction areas in the first type of sub-pixels; in the third type of sub-pixel, photoelectric reaction areas are arranged in the three light absorption layers.
8. An image sensor according to claim 3, wherein in said first type of sub-pixel, there are two light-absorbing layers in which there are photo-reactive regions; the photoelectric reaction areas are arranged in two layers of the light absorption layers of the second type of sub-pixels, wherein one photoelectric reaction area in the second type of sub-pixels is the same as one photoelectric reaction area in the first type of sub-pixels, and the other photoelectric reaction area in the second type of sub-pixels is different from the other photoelectric reaction area in the first type of sub-pixels; in the third type of sub-pixels, two layers of the light absorption layers are provided with the photoelectric reaction areas, wherein one photoelectric reaction area in the third type of sub-pixels is positioned at the same position as one photoelectric reaction area in the first type of sub-pixels, but is positioned at a different position from two photoelectric reaction areas in the second type of sub-pixels; the other one of the photo-reactive regions in the third type of sub-pixel is at the same location as one of the photo-reactive regions in the second type of sub-pixel, but at a different location from the two photo-reactive regions in the first type of sub-pixel.
9. An image sensor as in claim 3, wherein the area of the photo-sensing region in the first light-absorbing layer is smaller than the area of the photo-sensing regions in the second and third light-absorbing layers.
10. A method of manufacturing an image sensor, the image sensor comprising pixel cells, each of the pixel cells comprising at least three types of sub-pixels, the method comprising the steps of:
providing a substrate;
forming an isolation layer in the substrate, dividing the substrate into a plurality of light absorbing layers;
forming a photoelectric sensing region in the light absorption layer, wherein the photoelectric sensing region is arranged in at least one layer of the light absorption layer in each type of sub-pixels, and the positions of the photoelectric sensing regions are different in each type of sub-pixels; and
vertical gates are formed on the substrate, located in each type of sub-pixel, and extending into the light absorbing layer of the bottommost layer.
CN202211703032.9A 2022-12-22 2022-12-22 Image sensor and manufacturing method thereof Pending CN116130498A (en)

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Application Number Priority Date Filing Date Title
CN202211703032.9A CN116130498A (en) 2022-12-22 2022-12-22 Image sensor and manufacturing method thereof

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Publication Number Publication Date
CN116130498A true CN116130498A (en) 2023-05-16

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