CN114222080A - High dynamic pixel structure - Google Patents

High dynamic pixel structure Download PDF

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Publication number
CN114222080A
CN114222080A CN202111533033.9A CN202111533033A CN114222080A CN 114222080 A CN114222080 A CN 114222080A CN 202111533033 A CN202111533033 A CN 202111533033A CN 114222080 A CN114222080 A CN 114222080A
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node
suspension
floating
floating node
potential
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CN202111533033.9A
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CN114222080B (en
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陈多金
旷章曲
王菁
龚雨琛
陈杰
徐景星
衷世雄
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Will Semiconductor Ltd
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Will Semiconductor Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
    • H04N25/70—SSIS architectures; Circuits associated therewith
    • H04N25/76—Addressed sensors, e.g. MOS or CMOS sensors
    • 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
    • H01L27/1461—Pixel-elements with integrated switching, control, storage or amplification elements characterised by the photosensitive area
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
    • H04N25/50—Control of the SSIS exposure
    • H04N25/57—Control of the dynamic range
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
    • H04N25/50—Control of the SSIS exposure
    • H04N25/57—Control of the dynamic range
    • H04N25/59—Control of the dynamic range by controlling the amount of charge storable in the pixel, e.g. modification of the charge conversion ratio of the floating node capacitance

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (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)
  • Transforming Light Signals Into Electric Signals (AREA)

Abstract

The invention discloses a high dynamic pixel structure, which at least comprises a Photodiode (PD), a transmission Tube (TX), a suspension node (FD), a RESET tube (RESET), a Source Follower (SF), a row SELECT tube (SELECT), a power supply (VDD) and a pixel output (VOUT) which are arranged in a semiconductor substrate. FD comprises three regions of different area and different ion implantation concentration. By controlling the FD area, a variable FD capacitance and FD conversion gain are formed, and by controlling the doping concentration, a potential gradient is formed. Under the weak light, the high-potential FD1 acts, the FD1 corresponds to high conversion gain, a small amount of electrons can be converted into a strong voltage signal, and the problem that the photoelectric signal cannot be quantized due to weak light is solved. Under the strong light, the FD1, the FD2 and the FD3 act simultaneously, the conversion gain is small, the FD can collect a lot of photoelectrons, the problem of early saturation of the FD under the strong light is avoided, the light intensity range is effectively expanded, and the dynamic range of the pixel is expanded.

Description

High dynamic pixel structure
Technical Field
The present invention relates to an image sensor, and more particularly, to a high dynamic pixel structure.
Background
The image sensor is a commonly used device at present, and the pixel structure of the image sensor in the prior art has at least the following disadvantages:
under weak light, the photoelectric signal cannot be quantized because of weak light; under intense light, FD is prone to premature saturation. Therefore, the light intensity range is narrow.
In view of the above, the present invention is particularly proposed.
Disclosure of Invention
It is an object of the present invention to provide a high dynamic pixel structure to solve the above technical problems in the prior art.
The purpose of the invention is realized by the following technical scheme:
the high dynamic pixel structure of the invention comprises a photodiode 102, a transmission tube 103, a suspension node, a reset tube 110, a source follower 112, a row gate tube 113, a power supply 111 and a pixel output 114 which are arranged in a semiconductor substrate 101;
the number of the suspension nodes is three, and the three suspension nodes adopt regions with different areas and different ion implantation concentrations;
the three suspension nodes are a first suspension node 105, a second suspension node 107 and a third suspension node 109 from near to far in sequence from the transmission pipe 103;
variable floating node capacitance and floating node conversion gain are formed by controlling the areas of the three floating nodes, and potential gradient is formed by controlling the doping concentration.
Compared with the prior art, the high-dynamic pixel structure provided by the invention has the advantages that the FD comprises three regions with different areas and different ion implantation concentrations. By controlling the FD area, a variable FD capacitance and FD conversion gain are formed, and by controlling the doping concentration, a potential gradient is formed. Under the weak light, the high-potential FD1 acts, the FD1 corresponds to high conversion gain, a small amount of electrons can be converted into a strong voltage signal, and the problem that the photoelectric signal cannot be quantized due to weak light is solved. Under strong light, the FD1, the FD2 and the FD3 act simultaneously, the conversion gain is small, the FD can collect a lot of photoelectrons, and the problem of early saturation of the FD under the strong light is avoided, so that the pixel structure effectively expands the light intensity range, and the dynamic range of the pixel is expanded.
Drawings
Fig. 1 is a high dynamic pixel plane layout provided in an embodiment of the present invention;
fig. 2 is a sectional view a-a' of fig. 1.
In the figure:
101 semiconductor substrate (Silicon)
102 photodiode PD (photodiode)
103 transmission pipe (TX)
104 suspended node injection layer 1(FD imp1) As,10 to 50KeV,1E15 to 5E15
105 suspension node one (FD1)
106 suspended node implantation layer 2(FD imp2) As,10 to 50KeV,5E13 to 5E14
107 suspension node two (FD2)
108 suspended node injection layer 3(FD imp3) As,10 to 50KeV,5E12 to 5E13
109 suspension node three (FD3)
110 RESET tube (RESET)
111 power supply (VDD)
112 Source Follower (SF)
113 row gate pipe (SELECT)
114 Pixel output (Pixel out)
115 source drain implant
Detailed Description
The technical scheme in the embodiment of the invention is clearly and completely described below by combining the attached drawings in the embodiment of the invention; it is to be understood that the described embodiments are merely exemplary of the invention, and are not intended to limit the invention to the particular forms disclosed. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
The terms that may be used herein are first described as follows:
the term "and/or" means that either or both can be achieved, for example, X and/or Y means that both cases include "X" or "Y" as well as three cases including "X and Y".
The terms "comprising," "including," "containing," "having," or other similar terms of meaning should be construed as non-exclusive inclusions. For example: including a feature (e.g., material, component, ingredient, carrier, formulation, material, dimension, part, component, mechanism, device, process, procedure, method, reaction condition, processing condition, parameter, algorithm, signal, data, product, or article of manufacture), is to be construed as including not only the particular feature explicitly listed but also other features not explicitly listed as such which are known in the art.
The term "consisting of … …" is meant to exclude any technical feature elements not explicitly listed. If used in a claim, the term shall render the claim closed except for the inclusion of the technical features that are expressly listed except for the conventional impurities associated therewith. If the term occurs in only one clause of the claims, it is defined only to the elements explicitly recited in that clause, and elements recited in other clauses are not excluded from the overall claims.
Unless expressly stated or limited otherwise, the terms "mounted," "connected," and "secured," etc., are to be construed broadly, as for example: can be fixedly connected, can also be detachably connected or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms herein can be understood by those of ordinary skill in the art as appropriate.
The terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," and the like are used in an orientation or positional relationship that is indicated based on the orientation or positional relationship shown in the drawings for ease of description and simplicity of description only, and are not intended to imply or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting herein.
Details which are not described in detail in the embodiments of the invention belong to the prior art which is known to the person skilled in the art. Those not specifically mentioned in the examples of the present invention were carried out according to the conventional conditions in the art or conditions suggested by the manufacturer. The reagents or instruments used in the examples of the present invention are not specified by manufacturers, and are all conventional products available by commercial purchase.
The high dynamic pixel structure of the invention comprises a photodiode 102, a transmission tube 103, a suspension node, a reset tube 110, a source follower 112, a row gate tube 113, a power supply 111 and a pixel output 114 which are arranged in a semiconductor substrate 101;
the number of the suspension nodes is three, and the three suspension nodes adopt regions with different areas and different ion implantation concentrations;
the three suspension nodes are a first suspension node 105, a second suspension node 107 and a third suspension node 109 from near to far in sequence from the transmission pipe 103;
variable floating node capacitance and floating node conversion gain are formed by controlling the areas of the three floating nodes, and potential gradient is formed by controlling the doping concentration.
Under weak light, the high-potential suspension node I105 acts, the suspension node I105 corresponds to high conversion gain, a small amount of electrons can be converted into a strong voltage signal, and the phenomenon that photoelectric signals cannot be quantized due to weak illumination is avoided;
under strong light, the first suspension node 105, the second suspension node 107 and the third suspension node 109 act simultaneously, the conversion gain is small, the suspension nodes can collect a lot of photoelectrons, and premature saturation of the suspension nodes under the strong light is avoided.
The first suspension node 105 is subjected to small-area and high N-type ion implantation, the area of a second suspension node 107 adjacent to the first suspension node 105 is larger than that of the first suspension node 105, and the implantation concentration of the N-type ions is lower than that of the first suspension node 105;
the area of the floating node three 109 adjacent to the floating node two 107 is larger than that of the floating node two 107, and the N-type ion implantation concentration is lower than that of the floating node two 107.
When the reset tube 110 is turned on, the floating node I105, the floating node II 107 and the floating node III 109 are reset at the same time, the reset floating node forms a potential gradient, the potential of the floating node I105 is higher than that of the floating node II 107, and the potential of the floating node II 107 is higher than that of the floating node III 109.
Under weak light, the number of photo-generated electrons of the photodiode 102 is small, when the transmission tube 103 is conducted, electrons of the photodiode 102 are preferentially transferred to the floating node I105 with higher potential, the floating node I105 is not enough to accommodate with the continuous increase of light intensity, and the photo-generated electrons of the photodiode 102 occupy the floating node II 107 and the floating node III 109 in sequence.
In summary, in the high dynamic pixel structure of the embodiment of the invention, the FD includes three regions with different areas and different ion implantation concentrations. By controlling the FD area, a variable FD capacitance and FD conversion gain are formed, and by controlling the doping concentration, a potential gradient is formed. Under the weak light, the high-potential FD1 acts, the FD1 corresponds to high conversion gain, a small amount of electrons can be converted into a strong voltage signal, and the problem that the photoelectric signal cannot be quantized due to weak light is solved. Under strong light, the FD1, the FD2 and the FD3 act simultaneously, the conversion gain is small, the FD can collect a lot of photoelectrons, and the problem of early saturation of the FD under the strong light is avoided, so that the pixel structure effectively expands the light intensity range, and the dynamic range of the pixel is expanded.
In order to more clearly show the technical solutions and the technical effects provided by the present invention, the following detailed description is provided for the embodiments of the present invention with specific embodiments.
Example 1
As shown in fig. 1 and 2, the FD of the pixel structure is formed by sequentially forming FD1, FD2 and FD3 from the TX tube. FD1 is formed by small-area and high-N type ion implantation, and has FD2 adjacent to FD1, larger area than FD1 and lower N type ion implantation concentration than FD1, and FD3 adjacent to FD2, larger area than FD2 and lower N type ion implantation concentration than FD 2.
The principle of the embodiment is as follows:
FD comprises three regions of different area and different ion implantation concentration. The FD area is controlled to form variable FD capacitance and FD conversion gain, and the doping concentration is controlled to form potential gradient;
under weak light, the high-potential FD1 acts, the FD1 corresponds to high conversion gain, a small amount of electrons can be converted into a strong voltage signal, and the problem that the photoelectric signal cannot be quantized due to weak illumination is solved;
under strong light, the FD1, the FD2 and the FD3 act simultaneously, the conversion gain is small, the FD can collect a lot of photoelectrons, and the problem of early saturation of the FD under strong light is avoided;
the light intensity range is effectively expanded, and therefore the dynamic range of the pixels is expanded.
The specific adjusting process is as follows:
after the RESET is turned on, the FD1, the FD2, and the FD3 are RESET at the same time, the RESET FD forms a potential gradient, the potential of the FD1 is higher than that of the FD2, and the potential of the FD2 is higher than that of the FD 3. Under weak light, the number of photo-generated electrons of the PD is small, when TX is switched on, the electrons of the PD are preferentially transferred to FD1 with higher potential, FD1 is not enough to accommodate the electrons with increasing light intensity, and the photo-generated electrons of the PD occupy FD2 and FD3 in sequence.
According to the pixel structure, the area of FD1 is smaller than that of FD2, and the area of FD2 is smaller than that of FD 3. Under the weak light, only FD1 is effective, the conversion gain is highest, a small amount of electrons generated by the weak light can be effectively quantized, the FD1, the FD2 and the FD3 are effective along with the continuous increase of the light intensity, the conversion gain is reduced, and the early saturation of the FD is avoided.
Therefore, the dynamic range of the image sensor can be effectively expanded.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims. The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Claims (5)

1. A high dynamic pixel structure is characterized by comprising a photodiode (102), a transmission tube (103), a suspension node, a reset tube (110), a source follower (112), a row gate tube (113), a power supply (111) and a pixel output (114), wherein the photodiode (102), the transmission tube (103), the suspension node, the reset tube, the source follower (112), the row gate tube (113) and the pixel output (114) are arranged in a semiconductor substrate (101);
the number of the suspension nodes is three, and the three suspension nodes adopt regions with different areas and different ion implantation concentrations;
the three suspension nodes are a suspension node I (105), a suspension node II (107) and a suspension node III (109) from near to far in sequence from the transmission pipe (103);
variable floating node capacitance and floating node conversion gain are formed by controlling the areas of the three floating nodes, and potential gradient is formed by controlling the doping concentration.
2. The high dynamic pixel structure of claim 1, wherein:
under weak light, the high-potential suspension node I (105) acts, the suspension node I (105) corresponds to high conversion gain, a small amount of electrons can be converted into a strong voltage signal, and the phenomenon that photoelectric signals cannot be quantized due to weak light is avoided;
under strong light, the first suspension node (105), the second suspension node (107) and the third suspension node (109) act simultaneously, the conversion gain is small, the suspension nodes can collect a lot of photoelectrons, and premature saturation of the suspension nodes under the strong light is avoided.
3. The structure of claim 2, wherein the floating node one (105) is formed by a small area and high N-type ion implantation, and the floating node two (107) adjacent thereto has an area larger than that of the floating node one (105) and has a lower N-type ion implantation concentration than that of the floating node one (105);
the area of the suspension node three (109) adjacent to the suspension node two (107) is larger than that of the suspension node two (107) and the N-type ion implantation concentration is lower than that of the suspension node two (107).
4. A high dynamic pixel structure as claimed in claim 3, characterized in that when the reset transistor (110) is turned on, the floating node one (105), the floating node two (107) and the floating node three (109) are reset simultaneously, the floating node after reset forms a potential gradient, the potential of the floating node one (105) is higher than the potential of the floating node two (107), and the potential of the floating node two (107) is higher than the potential of the floating node three (109).
5. A high dynamic pixel structure as claimed in claim 4, wherein the number of photo-generated electrons of the photodiode (102) is small under weak light, when the transmission tube (103) is turned on, the electrons of the photodiode (102) are preferentially transferred to the floating node one (105) with higher potential, and as the light intensity is increased, the floating node one (105) is not enough to accommodate, and the photo-generated electrons of the photodiode (102) will occupy the floating node two (107) and the floating node three (109) in turn.
CN202111533033.9A 2021-12-15 2021-12-15 High dynamic pixel structure Active CN114222080B (en)

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CN114222080B CN114222080B (en) 2024-07-16

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1627524A (en) * 2003-12-12 2005-06-15 佳能株式会社 Photoelectric conversion device, method of manufacturing photoelectric conversion device, and image pickup system
US20070069322A1 (en) * 2005-09-28 2007-03-29 Jeon In G CMOS image sensor and method for manufacturing the same
CN103779365A (en) * 2012-10-19 2014-05-07 比亚迪股份有限公司 Pixel unit with wide dynamic range, manufacturing method thereof, and image sensor formed by same
CN104022133A (en) * 2014-06-10 2014-09-03 北京思比科微电子技术股份有限公司 Active pixel with floating diffusing node provided with variable capacitance and image sensor
CN113382184A (en) * 2021-06-09 2021-09-10 上海矽印科技有限公司 Method for automatically adjusting high dynamic range pixel by gain

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1627524A (en) * 2003-12-12 2005-06-15 佳能株式会社 Photoelectric conversion device, method of manufacturing photoelectric conversion device, and image pickup system
US20070069322A1 (en) * 2005-09-28 2007-03-29 Jeon In G CMOS image sensor and method for manufacturing the same
CN103779365A (en) * 2012-10-19 2014-05-07 比亚迪股份有限公司 Pixel unit with wide dynamic range, manufacturing method thereof, and image sensor formed by same
CN104022133A (en) * 2014-06-10 2014-09-03 北京思比科微电子技术股份有限公司 Active pixel with floating diffusing node provided with variable capacitance and image sensor
CN113382184A (en) * 2021-06-09 2021-09-10 上海矽印科技有限公司 Method for automatically adjusting high dynamic range pixel by gain

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