CN110233980B - Active pixel image sensor, image processing method and storage medium - Google Patents
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- 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
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- 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
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- 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
- H01L27/14643—Photodiode arrays; MOS imagers
- H01L27/14645—Colour imagers
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- H—ELECTRICITY
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- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/70—SSIS architectures; Circuits associated therewith
- H04N25/71—Charge-coupled device [CCD] sensors; Charge-transfer registers specially adapted for CCD sensors
- H04N25/75—Circuitry for providing, modifying or processing image signals from the pixel array
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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
Abstract
The embodiment of the application provides an active pixel image sensor, an image processing method and a storage medium, wherein the active pixel image sensor comprises the following components: at least three PD columns; a field effect transistor connected to the at least three PD columns; the at least three PD columns are used for absorbing monochromatic light of an R channel, a G channel and a B channel and converting corresponding optical signals into electric signals; each PD column is used for absorbing a monochromatic light; and the field effect transistor is used for sequentially reading out the electric signals of the PD columns and resetting. By adopting the implementation scheme, each pixel unit in the active pixel image sensor comprises at least three PD columns and the field-effect tube vertically connected with each PD column, and the signal readout can be realized by sharing one readout circuit by a plurality of PD columns by using the at least three PD columns and the field-effect tube.
Description
Technical Field
The present disclosure relates to the field of image processing, and in particular, to an active pixel image sensor, an image processing method, and a storage medium.
Background
The Pixel circuit of a Complementary Metal Oxide Semiconductor (CMOS) image Sensor can be divided into two types, namely a Passive Pixel Sensor (PPS) and an Active Pixel Sensor (APS), each Pixel in the APS corresponds to more than 3 transistors for implementing the amplified reading and resetting of signals in the Pixel, as shown in fig. 1, taking a 4T Pixel image Sensor as an example, the working flow of the APS is as follows: electron-hole pairs generated by light irradiation are separated by a Photodiode (PD) electric field, so that electrons move to an n region and holes move to a p region; activating a reset tube, resetting the read-out region to a high level, and reading out the reset level; then, activating a transfer gate, transferring the charges from the photosensitive area to the n + area and from the n + area, and reading out the signal level by matching with a gate tube; and obtaining the actual effective amplitude corresponding to the signal level by carrying out related double sampling on the reset level and the signal level.
However, the conventional APS requires three or more transistors, and the area occupied by the transistors is large, and in addition, each PD column can only use one readout circuit to perform signal readout, so that the size of the active pixel sensor is large, and when the size of the active pixel sensor needs to be reduced, the processing requirement for the transistors is increased.
Disclosure of Invention
The embodiment of the application provides an active pixel image sensor, an image processing method and a storage medium, which can realize that a plurality of PD columns share one reading circuit to read signals.
The technical scheme of the application is realized as follows:
the embodiment of the present application provides an active pixel image sensor, the active pixel image sensor includes:
at least three PD columns;
a field effect transistor connected to the at least three PD columns;
wherein the at least three PD pillars are used for absorbing monochromatic light of a Red (Red, R) channel, a Green (Green, G) channel and a Blue (Blue, B) channel and converting corresponding optical signals into electrical signals; each PD column is used for absorbing a monochromatic light;
and the field effect transistor is used for sequentially reading out the electric signals of the PD columns and resetting.
In the above scheme, the size of the PD column is determined based on the resonance wavelength of the RGB monochromatic light and the refractive index of the optical signal.
In the above scheme, the PD column is rectangular, circular, parallelogram or rhombus in shape.
In the above scheme, the field effect transistor includes a control gate and a floating gate corresponding to each PD pillar, an isolation strip is disposed between the control gate and the floating gate, and the control gate is connected to a gate of the field effect transistor.
In the above solution, the control gate is configured to focus the electrical signal to the n + region corresponding to the specific PD column by applying a forward bias when the specific PD column is gated; when the forward bias voltage is higher than a first voltage, transferring an electrical signal of an n + region into a floating gate corresponding to the specific PD column, wherein the specific PD column is any one of the at least three PD columns, and the first voltage is a voltage during tunneling between the n + region corresponding to the specific PD column and the floating gate corresponding to the specific PD column; and reading out the electric signal of the specific PD pillar when the drain electrode is forward biased and the voltage of the control gate is higher than the threshold voltage of the floating gate corresponding to the specific PD pillar, wherein the threshold voltage is determined by the signal intensity of the optical signal.
In the above scheme, the control gate is further configured to apply a reverse bias voltage, and when the reverse bias voltage is greater than a preset voltage threshold, the electrical signal is transferred from the floating gate corresponding to the specific PD column to the n + region corresponding to the specific PD column to perform a reset operation.
In the above scheme, the Field Effect Transistor is a floating gate Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET).
In the scheme, the n region of the PD column is connected with the p-type substrate of the field effect transistor.
The embodiment of the application provides an image processing method, which is applied to an active pixel image sensor, wherein the active pixel image sensor comprises at least three PD columns and field effect transistors connected with the at least three PD columns, and the method comprises the following steps:
absorbing the monochromatic light of the R channel, the G channel and the B channel by using the at least three PD columns, and converting corresponding optical signals into electric signals; wherein each PD column is used for absorbing a monochromatic light;
and sequentially reading out the electric signals of the PD columns by using the field effect transistor, and performing reset operation by using the field effect transistor so as to perform image processing on the electric signals to obtain corresponding images.
In the above scheme, the field effect transistor includes a control gate and a floating gate corresponding to each PD pillar, an isolation strip is disposed between the control gate and the floating gate, and the control gate is connected to a gate of the field effect transistor;
the utilizing the field effect transistor to read out the electric signals of the PD columns in sequence comprises the following steps:
focusing the electrical signal to an n + region corresponding to a particular PD pillar of the at least three PD pillars by applying a forward bias when the particular PD pillar is gated; the specific PD column is any one of the at least three PD columns,
when the forward bias voltage is higher than a first voltage, transferring an electric signal of the n + region into the floating gate corresponding to the specific PD column, wherein the first voltage is a voltage when tunneling is carried out between the n + region corresponding to the specific PD column and the floating gate corresponding to the specific PD column;
and reading out the electric signal of the specific PD pillar when the drain electrode is forward biased and the voltage of the control gate is higher than the threshold voltage of the floating gate corresponding to the specific PD pillar, wherein the threshold voltage is determined by the signal intensity of the optical signal.
In the foregoing solution, the performing the reset operation by using the field effect transistor includes:
applying a reverse bias to the control gate;
and when the reverse bias voltage is greater than a preset voltage threshold value, transferring the electric signal from the floating gate corresponding to the specific PD pillar to the n + region corresponding to the specific PD pillar so as to perform reset operation.
The embodiment of the application provides a storage medium, wherein a computer program is stored on the storage medium, is applied to an active pixel image sensor, and realizes any one of the image methods when being executed by a processor.
The embodiment of the application provides an active pixel image sensor, an image processing method and a storage medium, wherein the active pixel image sensor comprises the following components: at least three photodiode PD pillars; a field effect transistor connected to the at least three PD columns; the at least three PD columns are used for absorbing monochromatic light of an R channel, a G channel and a B channel and converting corresponding optical signals into electric signals; each PD column is used for absorbing a monochromatic light; and the field effect transistor is used for sequentially reading out the electric signals of the PD columns and resetting. Therefore, by adopting the implementation scheme, each pixel unit in the active pixel image sensor comprises at least three PD columns and the field effect tube vertically connected with each PD column, the process of processing the collected RGB monochromatic light can be realized by utilizing the at least three PD columns and the field effect tube, and a plurality of PD columns can share one reading circuit to read out signals.
Drawings
Fig. 1 is a circuit structure diagram of a 4T active pixel image sensor proposed in the prior art;
fig. 2 is a schematic structural diagram of an active pixel image sensor according to an embodiment of the present disclosure;
fig. 3 is a structural composition diagram of an exemplary active pixel image sensor according to an embodiment of the present disclosure;
FIG. 4(a) is a top view of a single pixel of an exemplary active pixel image sensor provided by an embodiment of the present application;
FIG. 4(b) is a top view of a single pixel of an exemplary active pixel image sensor as proposed in the prior art;
fig. 5 is a flowchart of an image processing method according to an embodiment of the present application.
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the present application. And are not intended to limit the present application.
Example one
An embodiment of the present application provides an active pixel image sensor, as shown in fig. 2, the active pixel image sensor 200 includes:
a PD column 201; wherein the number of PD columns is at least three.
A field effect transistor 202 connected to the PD column 201;
the PD column is used for absorbing monochromatic light of an R channel, a G channel and a B channel and converting corresponding optical signals into electric signals; each PD column is used for absorbing a monochromatic light;
the field effect transistor 202 is configured to sequentially read out and reset electrical signals of the PD pillars.
The active pixel image sensor provided by the embodiment of the application is suitable for image processing of collected optical signals to obtain an image corresponding to the optical signals in a scene.
In the embodiment of the application, the RGB monochromatic light absorbed by each PD column is subjected to photoelectric conversion in the depletion region of the PD column, the corresponding optical signal is converted into an electric signal, then the electric signal is transferred and read by the field effect transistor, and after the electric signal is read, the reset operation is performed.
Optionally, the size of each PD column is determined based on the resonant wavelength of the RGB monochromatic light and the refractive index of the light signal.
In the embodiment of the present application, each pixel of the active pixel image sensor includes a PD column with a diameter, and the diameter of the PD column is determined based on the resonance wavelength of the RGB monochromatic light and the refractive index of the optical signal, or is obtained through optical simulation, and is specifically selected according to an actual situation, which is not specifically limited in the embodiment of the present application.
In the embodiment of the application, the size of the PD column is determined by using the formula (1)
PD column size (resonance wavelength-predetermined constant)/refractive index (1)
Illustratively, the diameter of the PD column is 70nm, the absorption rate of the PD column to blue light is the highest, and the absorption rate is as high as more than 95%; the diameter of the PD column is 90nm, and the absorption rate of the PD column to green light is highest; the PD column has a diameter of 120nm and has the highest absorption of red light.
In the embodiment of the application, the active pixel image sensor realizes the resonance absorption of the RGB monochromatic light by using the optical resonance of the PD column.
Optionally, the PD column may be rectangular, circular, parallelogram, or rhombic, and may be specifically selected according to the actual situation, which is not specifically limited in the embodiment of the present application.
Optionally, the field effect transistor 202 includes a control gate and a floating gate corresponding to each PD pillar, an isolation strip is disposed between the control gate and the floating gate, and the control gate is connected to a gate of the field effect transistor.
Optionally, the n region of the PD column is connected to the p-type substrate of the fet.
In the embodiment of the present application, as shown in fig. 3, the structure of the active pixel image sensor is schematically illustrated, wherein an n region of each PD column is connected to a p-type substrate of a field effect transistor, a control gate is isolated from a floating gate by an isolation strip, and the control gate is connected to a gate of the field effect transistor.
Optionally, the control gate is configured to focus the electrical signal to an n + region corresponding to the specific PD column by applying a forward bias when the specific PD column is gated; when the forward bias voltage is higher than a first voltage, transferring an electrical signal of an n + region into a floating gate corresponding to the specific PD column, wherein the specific PD column is any one of the at least three PD columns, and the first voltage is a voltage during tunneling between the n + region corresponding to the specific PD column and the floating gate corresponding to the specific PD column; and reading out the electric signal of the specific PD pillar when the drain electrode is forward biased and the voltage of the control gate is higher than the threshold voltage of the floating gate corresponding to the specific PD pillar, wherein the threshold voltage is determined by the signal intensity of the optical signal.
Here, a gating circuit (not shown in fig. 3) may be provided for each PD column, and when any one PD column is gated by the gating circuit, an electrical signal generated by the PD column may be transferred to a corresponding n + region; when any one PD column is not gated, the electrical signal generated by the PD column is not transferred to the corresponding n + region.
In the embodiment of the application, the electric signal is gathered in the channel of the n + region by applying forward bias to the control gate of the field effect transistor, when the forward bias is higher than a first voltage during tunneling between the floating gate and the n + region, the electric signal of the n + region is transferred to the floating gate, and at the moment, the threshold voltage in the floating gate is increased, wherein the threshold voltage in the floating gate is in direct proportion to the signal intensity of the optical signal.
In the embodiment of the application, after the electric signal is transferred to the floating gate, the source electrode of the field effect transistor is grounded, the drain electrode is forward biased, the voltage of the control gate is recorded in real time, when the voltage of the control gate is higher than the threshold voltage of the floating gate, the drain electrode flows current, and at the moment, the signal level of the electric signal can be read through the amplifier.
Optionally, the control gate is further configured to apply a reverse bias voltage, and when the reverse bias voltage is greater than a preset voltage threshold, the electrical signal is transferred from the floating gate corresponding to the specific PD column to the n + region corresponding to the specific PD column, so as to perform a reset operation.
In the embodiment of the present application, after reading the signal level of the electrical signal, a reset operation needs to be performed on the floating gate, specifically, a reverse bias is applied to the control gate, when the reverse bias is greater than a preset voltage threshold, the electrical signal in the floating gate tunnels out to neutralize a hole in the n + region, so that the threshold voltage in the floating gate is reduced, and at this time, the reset operation on the floating gate is completed.
Optionally, the field effect transistor is a device such as a floating gate MOSFET having functions of reading out an electrical signal and resetting, and is specifically selected according to an actual situation, and the embodiment of the present application is not specifically limited.
In the embodiment of the application, the signals of a plurality of PD columns can be sequentially read by adopting the shared field effect transistor; for example, the three PD columns in fig. 3 may be sequentially referred to as a first PD column, a second PD column, and a third PD column from left to right, and optical signals of the three PD columns in one active pixel image sensor are converted into electrical signals, specifically, for each PD column, a photoelectric conversion process occurs in a depletion region of a photodiode after light passes through a filter.
Firstly, reading and resetting a first PD column, then reading and resetting a second PD column, and finally reading and resetting a third PD column; it can be seen that the embodiment of the present application can implement shared readout of electrical signals of multiple PD columns by using one fet.
As an embodiment, the active pixel image sensor may be a sub-wavelength size active pixel image sensor.
In the embodiment of the application, the electric signals of a plurality of PD columns can be shared and read by one field effect transistor aiming at a single pixel; the electric signals of the corresponding PD columns can be shared and read by one field effect transistor aiming at a plurality of pixels.
The following is an exemplary description taking a single pixel as an example.
As shown in fig. 4(a), for a top view of an exemplary active pixel image sensor provided in the embodiments of the present application, each pixel includes three different PD columns in a vertical direction, and in fig. 4, circles filled with different patterns represent PD columns for performing photoelectric conversion on light of different wavelengths, for example, three PD columns are respectively used for performing photoelectric conversion on optical signals of an R channel, a G channel, and a B channel.
Fig. 4(b) is a top view of a single pixel of an exemplary active pixel image sensor proposed in the prior art, as shown in fig. 4(b), an image sensor portion corresponding to each pixel includes 4 transistors in a vertical direction, which increases an area of the entire active pixel image sensor, whereas the active pixel image sensor in the present application only occupies spaces of a plurality of PD columns in the vertical direction, thereby reducing a size of the active pixel image sensor.
It is understood that each pixel unit in the active pixel image sensor includes PD pillars and field effect transistors vertically connected to the PD pillars, wherein the number of PD pillars is at least three; the PD columns and the field effect tube can realize the process of image processing of the collected RGB monochromatic light, and realize that a plurality of PD columns share one reading circuit to read out signals, so that the size of the active pixel image sensor can be reduced, the charge capacity of the field effect tube is improved, the integration level of the active pixel image sensor is improved, the utilization rate of the erasable floating gate MOSFET is improved, and the process difficulty is reduced.
Example two
The embodiment of the application provides an image processing method, which is applied to an active pixel image sensor, wherein the active pixel image sensor comprises PD columns and field effect transistors connected with the PD columns, and the number of the PD columns is at least three; as shown in fig. 5, the method may include:
s101, absorbing monochromatic light of an R channel, a G channel and a B channel by using a PD column, and converting corresponding optical signals into electric signals; wherein each PD column is used for absorbing a monochromatic light;
the image processing method provided by the embodiment of the application is suitable for a scene in which the acquired optical signals are subjected to image processing to obtain the images corresponding to the optical signals.
In the embodiment of the application, the RGB monochromatic light absorbed by each PD column is subjected to photoelectric conversion in the depletion region of the PD column, and a corresponding optical signal is converted into an electrical signal.
In the embodiment of the present application, each pixel of the active pixel image sensor includes at least three PD pillars with different diameters, and the diameter of each PD pillar is determined based on the resonance wavelength of the RGB monochromatic light and the refractive index of the optical signal, or is obtained through optical simulation, and is specifically selected according to an actual situation, which is not specifically limited in the embodiment of the present application.
In the embodiment of the present application, the PD column size is determined using formula (1). Illustratively, the diameter of the PD column is 70nm, the absorption rate of the PD column to blue light is the highest, and the absorption rate is as high as more than 95%; the diameter of the PD column is 90nm, and the absorption rate of the PD column to green light is highest; the PD column has a diameter of 120nm and has the highest absorption of red light.
In the embodiment of the application, the active pixel image sensor realizes the resonance absorption of the RGB monochromatic light by using the optical resonance of the PD column.
Optionally, the PD column may be rectangular, circular, parallelogram, or rhombic, and may be specifically selected according to the actual situation, which is not specifically limited in the embodiment of the present application.
And S102, sequentially reading the electric signals of the PD columns by using the field effect transistor, and performing reset operation by using the field effect transistor so as to perform image processing on the electric signals to obtain corresponding images.
After the active pixel image sensor converts an optical signal into an electrical signal by using the PD column, the active pixel image sensor reads the electrical signal by using the field effect transistor, and performs a reset operation by using the field effect transistor to perform image processing on the electrical signal, thereby obtaining a corresponding image.
In the embodiment of the present application, the process of sequentially reading out the electrical signals of the PD pillars by the active pixel image sensor using the field effect transistor specifically includes: when the specific PD column is gated, the active pixel image sensor collects the electric signal to an n + region corresponding to the specific PD column in at least three PD columns by applying forward bias to a control gate; the specific PD column is any one of the at least three PD columns; when the forward bias voltage is higher than a first voltage, the active pixel image sensor transfers the electric signal of the n + region to the floating gate corresponding to the specific PD column, and the first voltage is the voltage when tunneling is carried out between the n + region corresponding to the specific PD column and the floating gate corresponding to the specific PD column; and applying forward bias to the drain electrode, recording the voltage of the control gate, and reading the electric signal of the specific PD pillar when the voltage of the control gate is higher than the threshold voltage of the floating gate corresponding to the specific PD pillar, wherein the threshold voltage is determined by the signal intensity of the optical signal.
In the embodiment of the present application, the threshold voltage in the floating gate is proportional to the signal intensity of the optical signal.
In the embodiment of the application, after the electric signal is transferred to the floating gate, the source electrode of the field effect transistor is grounded, the drain electrode is forward biased, the voltage of the control gate is recorded in real time, when the voltage of the control gate is higher than the threshold voltage of the floating gate, the drain electrode flows current, and at the moment, the signal level of the electric signal is read through the amplifier.
In the embodiment of the present application, the process of performing the reset operation by using the field effect transistor in the active pixel image sensor specifically includes: the active pixel image sensor applies a reverse bias to the control gate; when the reverse bias voltage is larger than the preset voltage threshold value, the active pixel image sensor transfers the electric signal from the floating gate corresponding to the specific PD pillar to the n + region corresponding to the specific PD pillar so as to carry out reset operation.
In the embodiment of the present application, after reading the signal level of the electrical signal, a reset operation needs to be performed on the floating gate, specifically, a reverse bias is applied to the control gate, when the reverse bias is greater than a preset voltage threshold, the electrical signal in the floating gate tunnels out to neutralize a hole in the n + region, so that the threshold voltage in the floating gate is reduced, and at this time, the reset operation on the floating gate is completed.
In the embodiment of the application, after the active pixel image sensor reads out the electric signal by using the field effect transistor, the active pixel image sensor performs image processing on the electric signal to obtain a corresponding image.
In the embodiment of the application, the electric signals of a plurality of PD columns can be shared and read by one field effect transistor aiming at a single pixel; the electric signals of the corresponding PD columns can be shared and read by one field effect transistor aiming at a plurality of pixels.
It can be understood that each pixel unit in the active pixel image sensor comprises at least three PD columns and a field effect transistor vertically connected with the at least three PD columns, the process of image processing of the collected RGB monochromatic light can be realized by using the at least three PD columns and the field effect transistor, and the multiple PD columns can share one readout circuit to read out signals, so that the size of the active pixel image sensor can be reduced, the charge capacity of the field effect transistor is improved, the integration level of the active pixel image sensor is improved, the utilization rate of the erasable floating gate MOSFET is improved, and the process difficulty is reduced.
EXAMPLE III
The present application provides a storage medium, on which a computer program is stored, the computer readable storage medium storing one or more programs, the one or more programs being executable by one or more processors and being applied to an active pixel image sensor, and the computer program implementing any one of the image processing methods according to the second embodiment.
Specifically, the program instructions corresponding to an image processing method in the present embodiment, when read or executed by an electronic device, include the steps of:
absorbing the monochromatic light of the R channel, the G channel and the B channel by using the at least three PD columns, and converting corresponding optical signals into electric signals; wherein each PD column is used for absorbing a monochromatic light;
and sequentially reading out the electric signals of the PD columns by using the field effect transistor, and performing reset operation by using the field effect transistor so as to perform image processing on the electric signals to obtain corresponding images.
In an embodiment of the present invention, further, the field effect transistor includes a control gate and a floating gate, the field effect transistor is used to sequentially read out the electrical signals of the PD pillars, and the one or more programs are executed by the one or more processors, so as to specifically implement the following steps:
focusing the electrical signal to an n + region corresponding to a particular PD pillar of the at least three PD pillars by applying a forward bias when the particular PD pillar is gated; the specific PD column is any one of the at least three PD columns;
when the forward bias voltage is higher than a first voltage, transferring an electric signal of the n + region into the floating gate corresponding to the specific PD column, wherein the first voltage is a voltage when tunneling is carried out between the n + region corresponding to the specific PD column and the floating gate corresponding to the specific PD column;
and reading out the electric signal of the specific PD pillar when the drain electrode is forward biased and the voltage of the control gate is higher than the threshold voltage of the floating gate corresponding to the specific PD pillar, wherein the threshold voltage is determined by the signal intensity of the optical signal.
In this embodiment of the present application, further, the field effect transistor is used to perform a reset operation, and the one or more programs are executed by the one or more processors, so as to implement the following steps:
applying a reverse bias to the control gate;
and when the reverse bias voltage is greater than a preset voltage threshold value, transferring the electric signal from the floating gate corresponding to the specific PD pillar to the n + region corresponding to the specific PD pillar so as to perform reset operation.
The above description is only a preferred embodiment of the present application, and is not intended to limit the scope of the present application.
Claims (12)
1. An active pixel image sensor, comprising:
at least three photodiode PD pillars;
a field effect transistor connected to the at least three PD columns;
the at least three PD columns are used for absorbing monochromatic light of an R channel, a G channel and a B channel and converting corresponding optical signals into electric signals; each PD column is used for absorbing a monochromatic light through the optical resonance of the PD column;
the field effect transistor is used for sequentially reading out the electric signals of the PD columns and resetting the electric signals;
the field effect transistor comprises a control gate and a floating gate corresponding to each PD pillar; the control gate is used for reading out an electric signal of a specific PD pillar when the drain electrode is forward biased and the voltage of the control gate is higher than the threshold voltage of the floating gate corresponding to the specific PD pillar, the specific PD pillar is any one of the at least three PD pillars, and the threshold voltage is determined by the signal intensity of an optical signal.
2. The active pixel image sensor of claim 1, wherein the PD posts are sized based on resonant wavelengths of RGB monochromatic light and refractive indices of the light signals.
3. The active pixel image sensor of claim 1 or 2, wherein the PD pillars are rectangular, circular, parallelogram-shaped, or diamond-shaped in shape.
4. The active pixel image sensor of claim 1, wherein an isolation strip is disposed between the control gate and the floating gate, and the control gate is connected to a gate of the fet.
5. The active pixel image sensor of claim 4,
the control gate is used for gathering the electric signal to an n + region corresponding to the specific PD column by applying forward bias when the specific PD column is gated; when the forward bias voltage is higher than a first voltage, transferring an electrical signal of the n + region into the floating gate corresponding to the specific PD pillar, wherein the first voltage is a voltage when tunneling is carried out between the n + region corresponding to the specific PD pillar and the floating gate corresponding to the specific PD pillar.
6. The active pixel image sensor of claim 4,
and the control gate is also used for applying a reverse bias voltage, and when the reverse bias voltage is greater than a preset voltage threshold value, the electric signal is transferred from the floating gate corresponding to the specific PD pillar to the n + region corresponding to the specific PD pillar so as to carry out reset operation.
7. The active pixel image sensor of claim 1, wherein the field effect transistor is a floating gate metal-oxide semiconductor field effect transistor (MOSFET).
8. The active pixel image sensor of claim 1, wherein the n-region of the PD pillar is connected to a p-type substrate of a field effect transistor.
9. An image processing method applied to an active pixel image sensor including at least three Photodiode (PD) pillars and field effect transistors connected to the at least three PD pillars, the method comprising:
absorbing the monochromatic light of the R channel, the G channel and the B channel by using the at least three PD columns, and converting corresponding optical signals into electric signals; wherein each PD column is used for absorbing a monochromatic light through the optical resonance of the PD column;
sequentially reading out the electric signals of the PD columns by using the field effect transistor, and performing reset operation by using the field effect transistor so as to perform image processing on the electric signals to obtain corresponding images;
the field effect transistor comprises a control gate and a floating gate corresponding to each PD pillar; the utilizing the field effect transistor to read out the electric signals of the PD columns in sequence comprises the following steps:
and reading out the electric signal of a specific PD pillar when the drain electrode is forward biased and the voltage of the control gate is higher than the threshold voltage of the floating gate corresponding to the specific PD pillar, wherein the specific PD pillar is any one of the at least three PD pillars, and the threshold voltage is determined by the signal intensity of the optical signal.
10. The method of claim 9, wherein an isolation strip is disposed between the control gate and the floating gate, the control gate being connected to the gate of the fet;
the utilizing the field effect transistor to read out the electric signal of each PD post in proper order still includes:
focusing the electrical signal to an n + region corresponding to a particular PD pillar of the at least three PD pillars by applying a forward bias when the particular PD pillar is gated;
when the forward bias voltage is higher than a first voltage, transferring an electrical signal of the n + region into the floating gate corresponding to the specific PD pillar, wherein the first voltage is a voltage when tunneling is carried out between the n + region corresponding to the specific PD pillar and the floating gate corresponding to the specific PD pillar.
11. The method of claim 10, wherein said performing a reset operation with said fet comprises:
applying a reverse bias to the control gate;
and when the reverse bias voltage is greater than a preset voltage threshold value, transferring the electric signal from the floating gate corresponding to the specific PD pillar to the n + region corresponding to the specific PD pillar so as to perform reset operation.
12. A storage medium on which a computer program is stored for application to an active pixel image sensor, characterized in that the computer program, when being executed by a processor, carries out the method according to any one of claims 9-11.
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