CN115642166A - Photosensitive circuit structure and image sensor - Google Patents

Abstract

The application provides a photosensitive circuit structure and an image sensor, wherein the photosensitive circuit structure comprises a photosensitive photodiode and a compensation unit, the compensation unit comprises a compensation photodiode and a compensation capacitor, a first pole of the photosensitive photodiode and a first pole of the compensation photodiode are both electrically connected with a first voltage end, a second pole of the compensation photodiode is electrically connected with a first pole of the compensation capacitor, and the second pole of the photosensitive photodiode and a second pole of the compensation capacitor are both electrically connected to a signal output end; the compensation photodiode is used to generate a leakage current equal to that of the light sensing photodiode. The leakage current of the compensation photodiode can be neutralized with the leakage current of the photosensitive photodiode, so that the influence of the leakage current of the photosensitive photodiode on the structural performance of the photosensitive circuit can be eliminated. Therefore, the photosensitive circuit structure and the image sensor provided by the application can improve the performances of the photosensitive circuit structure and the image sensor.

Description

Photosensitive circuit structure and image sensor

Technical Field

The application relates to the technical field of semiconductors, in particular to a photosensitive circuit structure and an image sensor.

Background

The image sensor converts the light image on the light sensing surface into an electric signal in a proportional relation with the light image by utilizing the photoelectric conversion function of the photoelectric device. The image sensor has the characteristics of small volume, light weight, high integration level, high resolution, low power consumption and the like, so that the image sensor is widely applied to the fields of medical detection, fingerprint identification, health monitoring and the like.

In the related art, the operation process of the image sensor can be generally divided into reset, photoelectric conversion, and readout. The image sensor can comprise a plurality of pixel units, a driving circuit, a reading circuit and the like, wherein the pixel circuits in the pixel units convert received optical signals into electric signals, the electric signals are controlled to be started by the driving circuit in a time sequence mode, and the electric signals are processed into digital signals by the reading circuit through data lines and transmitted to an upper computer to form a digital image.

However, the performance of the above image sensor is to be improved.

Disclosure of Invention

In view of at least one of the above technical problems, embodiments of the present application provide a photosensitive circuit structure and an image sensor, which can improve the performance of the photosensitive circuit structure and the image sensor.

In order to achieve the above object, the embodiments of the present application provide the following technical solutions:

a first aspect of the embodiments of the present application provides a photosensitive circuit structure, including a photosensitive photodiode and a compensation unit, where the compensation unit includes a compensation photodiode and a compensation capacitor, a first electrode of the photosensitive photodiode and a first electrode of the compensation photodiode are both electrically connected to a first voltage terminal, a second electrode of the compensation photodiode is electrically connected to a first electrode of the compensation capacitor, and both the second electrode of the photosensitive photodiode and the second electrode of the compensation capacitor are electrically connected to a signal output terminal; the compensation photodiode is used for generating a leakage current equal to that of the photosensitive photodiode.

The photosensitive circuit structure that this application embodiment provided, photosensitive circuit structure can include sensitization photodiode and compensating unit, and the compensating unit can be used for neutralizing sensitization photodiode's leakage current to improve the performance of photosensitive circuit structure. The photosensitive photodiode and the compensation unit jointly form a photosensitive unit, and the compensation unit can also reduce the difference of dark currents of the photosensitive units in different pixel units, so that an image obtained by the image sensor is uniform. The compensation unit may include a compensation photodiode and a compensation capacitor, a first electrode of the photosensitive photodiode and a first electrode of the compensation photodiode are electrically connected to the first voltage terminal, a second electrode of the compensation photodiode is electrically connected to the first electrode of the compensation capacitor, and the second electrode of the photosensitive photodiode and the second electrode of the compensation capacitor are electrically connected to the signal output terminal. The compensation photodiode is used for generating a leakage current equal to that of the photosensitive photodiode. The leakage current of the compensation photodiode is transmitted to a first pole of the compensation capacitor, and charges are generated on a second pole of the compensation capacitor, and the charges on the second pole of the compensation capacitor are opposite to the charges on the first pole of the compensation capacitor in electrical property. The charge of the second pole of the compensation capacitor can be neutralized with the leakage current of the photosensitive photodiode, so that the influence of the leakage current of the photosensitive photodiode on the structural performance of the photosensitive circuit can be eliminated.

In a possible implementation manner, the light sensing circuit structure further includes a control unit, a first end of the control unit is electrically connected to the second pole of the light sensing photodiode and the second pole of the compensation capacitor, a second end of the control unit is electrically connected to the signal output end, and a control end of the control unit is electrically connected to the control signal end.

In this way, the control unit can control the output of the signal of the photo-sensing photodiode.

In a possible implementation manner, the photosensitive circuit structure further includes a reset unit, a first end of the reset unit is electrically connected to the second voltage terminal, a second end of the reset unit is electrically connected to the second electrode of the photosensitive photodiode and the second electrode of the compensation capacitor, and a control terminal of the reset unit is electrically connected to the reset signal terminal.

In one possible embodiment, the reset unit includes at least two reset transistors connected in series, the at least two reset transistors including a first reset transistor and a second reset transistor, a first electrode of the first reset transistor being electrically connected to the second voltage terminal and forming a first end of the reset unit, a second electrode of the first reset transistor being electrically connected to a first electrode of the second reset transistor, a second electrode of the second reset transistor being electrically connected to a second electrode of the photosensitive photodiode and a second electrode of the compensation capacitor and forming a second end of the reset unit;

the control electrode of the first reset transistor and the control electrode of the second reset transistor are both electrically connected with the reset signal terminal and form a control terminal of the reset unit.

Thus, the leakage current of the reset unit is small.

In a possible embodiment, the photosensitive circuit structure further includes an amplifying unit including an amplifying transistor, a first electrode of the amplifying transistor is electrically connected to the second voltage terminal, a second electrode of the amplifying transistor is electrically connected to the first terminal of the control unit, and a control electrode of the amplifying transistor is electrically connected to the second electrode of the photosensitive photodiode, the second electrode of the compensation capacitor, and the second terminal of the resetting unit.

Therefore, the photosensitive circuit structure is more sensitive to weak light and can be suitable for more scenes.

In a possible embodiment, the photosensitive circuit structure further includes an auxiliary transistor, a first pole of the auxiliary transistor is electrically connected to the second pole of the photosensitive photodiode and the second pole of the compensation capacitor, a second pole of the auxiliary transistor is electrically connected to the control pole of the amplifying transistor, and the control pole of the auxiliary transistor is electrically connected to the control signal terminal.

Thus, the leakage current between the photosensitive unit and the signal output end can be reduced; the leakage current between the photosensitive photodiode and the second voltage end can be reduced, and therefore the performance of the photosensitive circuit structure is further improved.

In a possible embodiment, the control unit comprises at least two control transistors connected in series, the at least two control transistors comprising a first control transistor and a second control transistor, a first pole of the first control transistor forming a first terminal of the control unit, a second pole of the first control transistor being electrically connected to a first pole of the second control transistor, a second pole of the second control transistor being electrically connected to the signal output terminal and forming a second terminal of the control unit, the control pole of the first control transistor and the control pole of the second control transistor both being electrically connected to the control signal terminal and forming the control terminal of the control unit.

Thus, the leakage current of the control unit is small.

In one possible embodiment, the light sensing photodiode is located on the light entrance side of the compensation photodiode.

Therefore, the photosensitive photodiode can shield light, so that the light cannot irradiate the compensation photodiode, and the compensation photodiode is in a light shielding state.

In one possible implementation mode, the photosensitive circuit structure comprises a substrate, the photosensitive photodiode and the compensation photodiode are both located on the substrate, the orthographic projection of the photosensitive photodiode on the substrate and the orthographic projection of the compensation photodiode on the substrate are not overlapped, and the light blocking piece is arranged on the light inlet side of the compensation photodiode.

Thus, the light blocking member can block light so that the light cannot irradiate the compensation photodiode, and the compensation photodiode is in a light blocking state.

A second aspect of the embodiments of the present application provides an image sensor including the photosensitive circuit structure in the first aspect.

The image sensor that this application embodiment provided, image sensor can include the sensitization circuit structure, and the sensitization circuit structure can include sensitization photodiode and compensating unit, and the compensating unit can be used for neutralizing sensitization photodiode's leakage current to improve the performance of sensitization circuit structure. The photosensitive photodiode and the compensation unit jointly form a photosensitive unit, and the compensation unit can also reduce the difference of dark currents of the photosensitive units in different pixel units, so that an image obtained by the image sensor is uniform. The compensation unit may include a compensation photodiode and a compensation capacitor, a first electrode of the photosensitive photodiode and a first electrode of the compensation photodiode are electrically connected to the first voltage terminal, a second electrode of the compensation photodiode is electrically connected to the first electrode of the compensation capacitor, and the second electrode of the photosensitive photodiode and the second electrode of the compensation capacitor are electrically connected to the signal output terminal. The compensation photodiode is used to generate a leakage current equal to that of the light sensing photodiode. The leakage current of the compensation photodiode is transmitted to a first pole of the compensation capacitor, and charges are generated on a second pole of the compensation capacitor, and the charges on the second pole of the compensation capacitor are opposite to the charges on the first pole of the compensation capacitor in electrical property. The charge of the second pole of the compensation capacitor can be neutralized with the leakage current of the photosensitive photodiode, so that the influence of the leakage current of the photosensitive photodiode on the structural performance of the photosensitive circuit can be eliminated.

The construction of the present application and other objects and advantages thereof will be more apparent from the following description of the preferred embodiments taken in conjunction with the accompanying drawings.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is an equivalent circuit diagram of a photosensitive circuit structure provided in an embodiment of the present application;

FIG. 2 is another equivalent circuit diagram of a photosensitive circuit structure according to an embodiment of the present disclosure;

FIG. 3 is another equivalent circuit diagram of a photo sensor circuit structure according to an embodiment of the present disclosure;

FIG. 4 is another equivalent circuit diagram of a photosensitive circuit structure according to an embodiment of the present disclosure;

FIG. 5 is another equivalent circuit diagram of a photosensitive circuit structure according to an embodiment of the present disclosure;

FIG. 6 is another equivalent circuit diagram of a photosensitive circuit structure provided in the present application;

FIG. 7 is another equivalent circuit diagram of a photosensitive circuit structure according to an embodiment of the present disclosure;

FIG. 8 is a timing diagram illustrating an operation of a photosensitive circuit structure according to an embodiment of the present disclosure;

FIG. 9 is a schematic structural diagram of a photo sensing photodiode and a compensation photodiode provided in an embodiment of the present application;

fig. 10 is another schematic structural diagram of a photo sensing photodiode and a compensation photodiode provided in the embodiment of the present application.

Description of the reference numerals:

100: a light sensing circuit structure; 110: a light sensing unit;

111: a compensation unit; 120: a control unit;

130: a reset unit; 140: an amplifying unit;

150: a substrate; 161: a first voltage terminal;

162: a second voltage terminal; 163: a signal output terminal;

164: a control signal terminal; 165: a reset signal terminal;

170: a light barrier.

Detailed Description

In the related art, the image sensor may include a plurality of pixel units, a driving circuit, a readout circuit, and the like, where each pixel unit includes a pixel circuit, and the pixel circuit converts a received optical signal into an electrical signal, is turned on by the driving circuit under timing control, and is processed into a digital signal by the readout circuit via a data line. Each pixel circuit may include a transistor and a photodiode, and an anode of the photodiode is electrically connected to a reverse bias voltage.

However, the photodiode generates a dark current under the reverse bias voltage, thereby affecting the performance of the image sensor. In addition, the dark current difference of the photodiodes in different pixel units is large due to process errors and equipment differences, so that the uniformity of the image obtained by the image sensor is poor.

Based on at least one technical problem mentioned above, the embodiment of the present application provides a photosensitive circuit structure and an image sensor, the photosensitive circuit structure may include a photosensitive photodiode and a compensation unit, and the compensation unit may be configured to neutralize a leakage current of the photosensitive photodiode, so as to improve performance of the photosensitive circuit structure. The photosensitive photodiode and the compensation unit jointly form a photosensitive unit, and the compensation unit can also reduce the difference of dark currents of the photosensitive units in different pixel units, so that an image obtained by the image sensor is uniform. The compensation unit may include a compensation photodiode and a compensation capacitor, a first electrode of the photosensitive photodiode and a first electrode of the compensation photodiode are electrically connected to the first voltage terminal, a second electrode of the compensation photodiode is electrically connected to the first electrode of the compensation capacitor, and the second electrode of the photosensitive photodiode and the second electrode of the compensation capacitor are electrically connected to the signal output terminal. The compensation photodiode is used to generate a leakage current equal to that of the light sensing photodiode. The leakage current of the compensation photodiode is transmitted to the first pole of the compensation capacitor, and charges are generated on the second pole of the compensation capacitor, and the charges on the second pole of the compensation capacitor are opposite to the charges on the first pole of the compensation capacitor in electrical property. The charge of the second pole of the compensation capacitor can be neutralized with the leakage current of the photosensitive photodiode, so that the influence of the leakage current of the photosensitive photodiode on the structural performance of the photosensitive circuit can be eliminated.

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The image sensor provided by the embodiment of the present application will be described below with reference to fig. 1 to 10.

In the image sensor provided by the embodiment of the present application, the image sensor may include a plurality of pixel units arranged at intervals, for example, the pixel units may be arranged in an array. Each pixel unit may include a photosensitive circuit structure 100 therein, and the photosensitive circuit structure 100 may be configured to convert a received optical signal into an electrical signal.

The image sensor may further include a first voltage line, a second voltage line, a control signal line, a reset signal line, a Data line Data (fig. 3), and the like, and the plurality of photosensitive circuit structures 100 are electrically connected to the first voltage line, the second voltage line, the control signal line, the reset signal line, the Data line Data, and the like.

The photosensitive circuit structure 100 provided in the embodiment of the present application is explained below.

Referring to fig. 1, the light sensing circuit structure 100 may include a light sensing unit 110, a first terminal of the light sensing unit 110 may be electrically connected to a first voltage terminal 161, and a second terminal of the light sensing unit 110 may be electrically connected to a signal output terminal 163. The first voltage terminal 161 may be used to electrically connect to a first voltage line, thereby providing a first voltage to the photosensitive circuit structure 100. For example, the first voltage may be a reverse bias voltage Vbias. The signal output terminal 163 may be electrically connected to the Data line Data (fig. 3), and read the output signal Vout by the reading circuit.

One of the first end and the second end of the photosensitive unit 110 may be an input end of the photosensitive unit 110, and the other one of the first end and the second end of the photosensitive unit 110 may be an output end of the photosensitive unit 110. The first and second ends of other circuit units in this embodiment of the application may be similar to the photosensitive unit 110, and are not described again.

With continued reference to fig. 1, the light sensing unit 110 may include a light sensing photodiode D1 and a compensation unit 111, a first pole D11 of the light sensing photodiode D1 and a first end of the compensation unit 111 are electrically connected to a first voltage terminal 161, and a second pole D12 of the light sensing photodiode D1 and a second end of the compensation unit 111 are electrically connected to a signal output terminal 163. The compensation unit 111 may be used to neutralize the leakage current of the light sensing unit 110, thereby improving the performance of the light sensing circuit structure 100. For example, in the absence of light, when the reverse bias voltage Vbias is applied, the photodiode D1 will pass a small reverse leakage current, which is also called dark current. Since the total current output by the photo diode D1 is the sum of the leakage current generated when the photo diode D1 is in the operating state and not illuminated and the current generated by illumination, reducing the leakage current of the photo diode D1 can improve the sensitivity of the photo circuit structure 100 to light. In addition, the compensation unit 111 may also reduce the difference in leakage current of the light sensing unit 110 in different pixel units, thereby improving the uniformity of an image obtained by the image sensor.

One of the first pole D11 and the second pole D12 of the photo diode D1 may be an anode of the photo diode D1, and the other of the first pole D11 and the second pole D12 of the photo diode D1 may be a cathode of the photo diode D1. Taking the first pole D11 of the photo diode D1 as an anode as an example, the first voltage terminal 161 may input the reverse bias voltage Vbias to the anode of the photo diode D1. The first and second poles of the other photodiodes in the embodiment of the present application are similar to the photosensitive photodiode D1, and are not described again.

With continued reference to fig. 1, the compensation unit 111 may include a compensation photodiode D2 and a compensation capacitor C, the first pole D11 of the sensing photodiode D1 and the first pole D21 of the compensation photodiode D2 are electrically connected to the first voltage terminal 161, the second pole D22 of the compensation photodiode D2 is electrically connected to the first pole C1 of the compensation capacitor C, and the second pole D12 of the sensing photodiode D1 and the second pole C2 of the compensation capacitor C are electrically connected to the signal output terminal 163. Under the action of the first voltage input from the first voltage terminal 161, the photo sensing photodiode D1 generates a first leakage current, and the compensation photodiode D2 generates a second leakage current. When the second leakage current is transmitted to the first pole C1 of the compensation capacitor C, a first charge is generated on the first pole C1 of the compensation capacitor C, the first charge causes a second charge to be generated on the second pole C2 of the compensation capacitor C, and the first charge and the second charge have opposite electrical properties. The second charge is opposite in electrical property to the first leakage current, so that the first leakage current can be neutralized. Therefore, the compensation unit 111 can reduce the leakage current of the photosensitive unit 110 to improve the sensitivity of the photosensitive circuit structure 100 to light, thereby improving the performance of the photosensitive circuit structure 100. The first pole C1 and the second pole C2 of the compensation capacitor C are two electrodes of the compensation capacitor C.

In addition, in a light environment, the photo diode D1 may be irradiated with light to generate a photo current. The compensation photodiode D2 may be always in a light-shielding state (the light-shielding state will be described in the following embodiments), and the compensation photodiode D2 cannot be irradiated with light and cannot generate photocurrent. For example, the second leakage current generated by the compensation photodiode D2 may be smaller than or equal to the first leakage current generated by the photosensitive photodiode D1, so as to reduce the influence of the first leakage current on the performance of the photosensitive circuit structure 100. When the first leakage current is equal to the second leakage current, the first leakage current and the second leakage current can be completely neutralized, so that the improvement effect on the performance of the photosensitive circuit structure 100 is better.

The working process of the light sensing circuit structure 100 may be: when the light sensing unit 110 is not irradiated with light, the leakage currents generated by the light sensing photodiode D1 and the compensation photodiode D2 in the light sensing unit 110 are neutralized with each other. When the light sensing unit 110 is irradiated by light, the light sensing photodiode D1 of the light sensing unit 110 may convert the received light signal into an electrical signal and transmit the electrical signal to the signal output terminal 163.

Referring to fig. 2, the light sensing circuit structure 100 may further include a control unit 120, a first terminal of the control unit 120 may be electrically connected to the second pole D12 of the light sensing photodiode D1 and the second pole C2 of the compensation capacitor C, a second pole of the control unit 120 may be electrically connected to the signal output terminal 163, and a control terminal of the control unit 120 is electrically connected to the control signal terminal 164. The control signal terminal 164 may be electrically connected with the control signal line to provide the control signal Gate to the light sensing circuit structure 100.

The working process of the photosensitive circuit structure 100 may be: when the light sensing unit 110 is not irradiated with light, the leakage currents generated by the light sensing photodiode D1 and the compensation photodiode D2 in the light sensing unit 110 are neutralized with each other. When the light sensing unit 110 is irradiated by light, the light sensing photodiode D1 of the light sensing unit 110 may convert the received light signal into an electrical signal, and the electrical signal may be transmitted to the first end of the control unit 120, so as to control the on/off of the control unit 120 by the control signal Gate of the control signal terminal 164. When the control unit 120 is turned on, the tracking signal may be transmitted to the second terminal of the control unit 120.

The control unit 120 may include at least one control transistor, and the control unit 120 may include 1, 2, 3, or 4 or more control transistors. In some examples, referring to fig. 3, the control unit 120 may include a first control transistor T1 and a second control transistor T2 connected in series. The first pole T11 of the first control transistor T1 may be electrically connected to the second terminal of the light sensing unit 110 and form a first terminal of the control unit 120. The second pole T12 of the first control transistor T1 is electrically connected to the first pole T21 of the second control transistor T2. The second pole T22 of the second control transistor T2 is electrically connected to the signal output terminal 163 and forms a second terminal of the control unit 120. The control electrode of the first control transistor T1 and the control electrode of the second control transistor T2 are both electrically connected to the control signal terminal 164 and form a control terminal of the control unit 120. In other examples, referring to fig. 2, the control unit 120 may include only the first control transistor T1, and the first pole T11 of the first control transistor T1 may be electrically connected to the second terminal of the light sensing unit 110 and form the first terminal of the control unit 120. The second pole T12 of the first control transistor T1 forms a second terminal of the control unit 120, and the control pole of the first control transistor T1 forms a control terminal of the control unit 120. The principle of which has been elucidated and will not be described in detail.

The first and second control transistors T1 and T2 may be turned on by a control signal Gate controlling the control electrodes of the first and second control transistors T1 and T2, so that the electric signal transmitted to the control unit 120 is transmitted from the first terminal of the control unit 120 to the second terminal of the control unit 120. When the number of the control transistors is plural, plural control transistors may be connected in series, and the leakage current of plural control transistors is smaller than that of a single control transistor, so that the performance of the light sensing circuit structure 100 may be improved. The smaller the leakage current of the control unit 120, the less noise is doped in the electrical signal output via the control unit 120, so that the signal-to-noise ratio of the output signal Vout can be improved by reducing the leakage current of the control unit 120. When the leakage current of the control unit 120 is reduced, the difference of the leakage current of the control unit 120 in different pixel units may also be reduced, thereby improving the uniformity of the image obtained by the image sensor. When the number of the control transistors is 2, the control unit 120 can be ensured to have a smaller leakage current on the premise that the number of the control transistors is smaller.

One of the first pole and the second pole of the control transistor may be a drain of the control transistor, the other of the first pole and the second pole of the control transistor may be a source of the control transistor, and the control pole of the control transistor may be a gate of the control transistor. The type of control transistor may be a P-type transistor or an N-type transistor. Different enable levels are provided according to different transistor types. The enable level refers to a level at which the transistor can be turned on. Illustratively, when the transistor is a P-type transistor, the enable level is low. When the transistor is an N-type transistor, the enable level is high. Other transistors in the embodiments of the present application are similar to the control transistor, and are not described again.

Referring to fig. 4 and 5, the photo sensing circuit structure 100 may further include a reset unit 130, a first terminal of the reset unit 130 is electrically connected to the second voltage terminal 162, a second terminal of the reset unit 130 is electrically connected to the second diode D12 of the photo sensing photodiode D1 and the second diode C2 of the compensation capacitor C, and a control terminal of the reset unit 130 is electrically connected to the reset signal terminal 165. The Reset signal terminal 165 may be electrically connected to the Reset signal line to provide a Reset signal Reset to the light sensing circuit structure 100. The second voltage terminal 162 may be electrically connected to a second voltage line to provide a second voltage to the light sensing circuit structure 100. For example, the second voltage may be VDD.

The working process of the light sensing circuit structure 100 may be: when the light sensing unit 110 is not irradiated with light, the leakage currents generated by the light sensing photodiode D1 and the compensation photodiode D2 in the light sensing unit 110 are neutralized with each other. The reset unit 130 is turned on to make the second voltage terminal 162 input an electrical signal to the light sensing unit 110, and is turned off when the light sensing unit 110 has an initial electrical signal. When the light sensing unit 110 is irradiated by light, the light sensing photodiode D1 of the light sensing unit 110 may convert the received light signal into an electrical signal, and the electrical signal is combined with the initial electrical signal to form a composite electrical signal, and the composite electrical signal is transmitted to the first end of the control unit 120. The control unit 120 is turned on to transmit the composite electrical signal to the signal output terminal 163.

For example, the reset unit 130 may include at least one reset transistor, and the reset unit 130 may include 1, 2, 3, or 4 or more reset transistors. For example, the reset unit 130 may include a first reset transistor T3 and a second reset transistor T4 connected in series. The first pole T31 of the first reset transistor T3 is electrically connected to the second voltage terminal 162 and forms a first terminal of the reset unit 130. The second pole T32 of the first reset transistor T3 is electrically connected to the first pole T41 of the second reset transistor T4, and the second pole T42 of the second reset transistor T4 is electrically connected to the second pole D12 of the photosensitive photodiode D1 and the second pole C2 of the compensation capacitor C, and forms a second terminal of the reset unit 130. A control electrode of the first reset transistor T3 and a control electrode of the second reset transistor T4 are electrically connected to the reset signal terminal 165 and form a control terminal of the reset unit 130.

The first and second Reset transistors T3 and T4 may be turned on by a Reset signal Reset controlling the control electrodes of the first and second Reset transistors T3 and T4, thereby allowing VDD to be transmitted from the first terminal of the Reset unit 130 to the second terminal of the Reset unit 130. When the quantity of reset transistor is a plurality of, a plurality of reset transistor can establish ties, and the leakage current of a plurality of reset transistor compares that single reset transistor's leakage current is littleer, can reduce signal noise, guarantees the authenticity and the accuracy of compound signal of telecommunication to can improve photosensitive circuit structure 100 performance. In addition, it is also possible to reduce the difference in the leakage current of the reset unit 130 in different pixel units, thereby improving the uniformity of an image obtained by the image sensor. When the number of the reset transistors is 2, the reset unit 130 can be ensured to have a smaller leakage current on the premise that the number of the reset transistors is smaller.

With continued reference to fig. 4 and 5, the light sensing circuit structure 100 may further include an amplifying unit 140, a first terminal of the amplifying unit 140 is electrically connected to the second voltage terminal 162, a second terminal of the amplifying unit 140 is electrically connected to the first terminal of the control unit 120, and a control terminal of the amplifying unit 140 is electrically connected to the second terminal of the light sensing unit 110 and the second terminal of the reset unit 130.

The working process of the photosensitive circuit structure 100 may be: when the light sensing unit 110 is not irradiated with light, the leakage currents generated by the light sensing photodiode D1 and the compensation photodiode D2 in the light sensing unit 110 are neutralized with each other. The reset unit 130 is turned on to make the second voltage terminal 162 input an electrical signal to the light sensing unit 110, and is turned off when the light sensing unit 110 has an initial electrical signal. When the light sensing unit 110 is irradiated by light, the light sensing photodiode D1 of the light sensing unit 110 may convert the received optical signal into an electrical signal, the electrical signal is combined with the initial electrical signal to form a composite electrical signal, and the composite electrical signal is transmitted to the control end of the amplifying unit 140, so that the second end of the amplifying unit 140 may follow the composite electrical signal and output a following electrical signal corresponding to the composite electrical signal. The follow electrical signal may be transmitted to a first terminal of the control unit 120, and the control unit 120 is turned on to transmit the follow electrical signal to the signal output terminal 163.

Illustratively, the amplifying unit 140 may include an amplifying transistor T5, and the first pole T51 of the amplifying transistor T5 is electrically connected to the second voltage terminal 162 and forms a first terminal of the amplifying unit 140. The second pole T52 of the amplifying transistor T5 is electrically connected to the first terminal of the control unit 120 and forms a second terminal of the amplifying unit 140. A control terminal of the amplifying transistor T5 is electrically connected to the second diode D12 of the photo sensing photodiode D1, the second diode C2 of the compensation capacitor C, and the second terminal of the reset unit 130, and forms a control terminal of the amplifying unit 140.

In the embodiment where the photosensitive circuit structure 100 is not provided with the amplifying unit 140 and the reset unit 130, the photosensitive circuit structure 100 has a simpler structure and is easier to implement. In the embodiment in which the amplifying unit 140 and the resetting unit 130 are disposed in the light sensing circuit structure 100, the light sensing circuit structure 100 is more sensitive to weak light, and can be applied to more scenes. For example, it can be used for underscreen fingerprint recognition.

Referring to fig. 6 and 7, the photosensitive circuit structure 100 may further include an auxiliary transistor T6, a first pole T61 of the auxiliary transistor T6 is electrically connected to the second pole D12 of the photosensitive photodiode D1 and the second pole C2 of the compensation capacitor C, a second pole T62 of the auxiliary transistor T6 is electrically connected to the control pole of the amplifying transistor T5, and the control pole of the auxiliary transistor T6 is electrically connected to the control signal terminal 164.

On one hand, the auxiliary transistor T6 and the control unit 120 can jointly control the transmission of the electrical signal generated by the light sensing unit 110 to the signal output terminal 163, which is equivalent to increasing the number of control transistors of the control unit 120, so that the leakage current between the light sensing unit 110 and the signal output terminal 163 can be reduced. At this time, even if the control unit 120 only provides one control transistor, the control unit 120 can make the leakage current between the light sensing unit 110 and the signal output terminal 163 smaller under the synergistic effect of the auxiliary transistor T6, thereby improving the performance of the light sensing circuit structure 100. On the other hand, the auxiliary transistor T6 is located between the reset unit 130 and the light sensing unit 110, and the auxiliary transistor T6 can reduce a leakage current between the light sensing unit 110 and the second voltage terminal 162, thereby further improving the performance of the light sensing circuit structure 100.

The specific operation of the photosensitive circuit structure 100 in fig. 6 is described below.

Referring to fig. 6 and 8, first of all, during the initial power-on phase (T1), the first Reset transistor T3 and the second Reset transistor T4 in the Reset unit 130 are turned on under the control of the Reset signal Reset, and the second pole T42 of the second Reset transistor T4 is electrically connected to the control pole of the amplifying transistor T5 to Reset the control pole of the amplifying transistor T5. After a preset time, the control electrode of the amplifying transistor T5 obtains an initial voltage, and the Reset signal Reset of the Reset signal terminal 165 controls the first Reset transistor T3 and the second Reset transistor T4 to turn off.

Following the photoelectric conversion stage (t 2), in a light environment, the light sensing unit 110 is exposed to light, and the light sensing photodiode D1 generates a photocurrent and injects electrons to the negative electrode side of the light sensing photodiode D1, so that the voltage at the negative electrode side of the light sensing photodiode D1 continuously decreases.

Then, in an electrical signal reading phase (T3), after the light sensing unit 110 is exposed for a period of time, the first control transistor T1 and the auxiliary transistor T6 are turned on under the control of the control signal Gate, the first pole T11 of the first control transistor T1 obtains the voltage signal from the second pole T52 of the amplifying transistor T5, the voltage signal is output after passing through the second pole T12 of the first control transistor T1, the voltage signal is transmitted to the Data line Data and transmitted to the reading circuit through the Data line Data, and the reading circuit outputs the reading signal Read, thereby reading the voltage signal.

Since the change of the photocurrent of the light sensing unit 110 is positively correlated with the voltage change at the negative electrode side of the light sensing photodiode D1, and the voltage change at the negative electrode side of the light sensing photodiode D1 is positively correlated with the illumination intensity, the larger the illumination intensity is, the larger the voltage change at the negative electrode side of the light sensing photodiode D1 is, the smaller the voltage value at the negative electrode side of the light sensing photodiode D1 is, the smaller the output voltage value of the amplifying unit 140 is, and the smaller the voltage signal output by the control unit 120 is, so that the illumination intensity irradiated on the light sensing photodiode D1 can be determined by detecting the magnitude of the voltage signal output by the control unit 120.

In the working process of the photosensitive photodiode D1, there is also a reverse bias stage, which can be set between multiple photoelectric conversion stages according to the user's requirement, to ensure the stability of the working performance of the photosensitive photodiode D1. Since electrons are injected from the cathode side of the photo diode D1 for a long time, the photo diode D1 is biased, and the photoelectric conversion process of the photo diode D1 is affected. Therefore, it needs to be reverse bias adjusted. A specific procedure may be to supply a reverse bias voltage Vbias to the positive electrode side of the photosensitive photodiode D1 through the reverse first voltage terminal 161, to eliminate the bias voltage in the photosensitive photodiode D1, and to maintain the efficient photoelectric conversion performance of the photosensitive photodiode D1.

The compensation photodiode D2 provided in the embodiment of the present application is described below as being in a light-shielding state.

Referring to fig. 9 and 10, the photosensitive circuit structure 100 may be disposed on a substrate 150, and the substrate 150 may provide a supporting base for other structural layers on the substrate 150. The material of the substrate 150 may be single crystal silicon, polycrystalline silicon, amorphous silicon, germanium silicide, silicon carbide, gallium nitride, or the like. The substrate 150 may be a Bulk Silicon (Bulk Silicon) substrate, or may be a Silicon On Insulator (SOI) substrate. The substrate 150 may also be formed of other organic or inorganic materials, for example, the material of the substrate 150 may include Polyimide (PI) or polyethylene, etc.

Both the sensing photodiode D1 and the compensation photodiode D2 may be located on the substrate 150. In some examples, referring to fig. 9, the light sensing photodiode D1 may be located at the light incident side of the compensation photodiode D2. Under the illumination environment, light can shine on sensitization photodiode D1, and sensitization photodiode D1 can shelter from light to make light can't shine compensation photodiode D2, thereby make compensation photodiode D2 be in the shading state. For example, the photo sensing photodiode D1 and the compensation photodiode D2 may be stacked on the substrate 150 in a thickness direction of the substrate 150. The orthographic projection of the light sensing photodiode D1 on the substrate 150 covers the orthographic projection of the compensation photodiode D2 on the substrate 150. In other examples, referring to fig. 10, the orthographic projection of the sensitive photodiode D1 on the substrate 150 and the orthographic projection of the compensation photodiode D2 on the substrate 150 do not overlap, and the distance between the orthographic projection of the sensitive photodiode D1 on the substrate 150 and the orthographic projection of the compensation photodiode D2 on the substrate 150 may be greater than or equal to 0. For example, the film layers in the photo diode D1 and the compensation photodiode D2 may be disposed on the same layer and material, so that the fabrication processes of the photo diode D1 and the compensation photodiode D2 may be simplified. The light blocking member 170 may be disposed on the light incident side of the compensation photodiode D2, and in an illumination environment, light may be irradiated on the light blocking member 170, and the light blocking member 170 may block the light, so that the light may not be irradiated on the compensation photodiode D2, and the compensation photodiode D2 is in a light blocking state. For example, the orthographic projection of the flag 170 on the substrate 150 may cover the orthographic projection of the compensation photodiode D2 on the substrate 150.

The term "same layer and same material" refers to a base film layer formed from the same material, and after the base film layer is patterned and/or subjected to other processing techniques, different parts of the base film layer are respectively formed into a plurality of structural film layers. The treatment processes of the formed different structural film layers can be the same or different, and the formed different structural film layers can have the same or different thicknesses and can be on the same horizontal plane or different horizontal planes.

Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.

Claims (10)

1. A photosensitive circuit structure is characterized by comprising a photosensitive photodiode and a compensation unit, wherein the compensation unit comprises a compensation photodiode and a compensation capacitor,

the first electrode of the photosensitive photodiode and the first electrode of the compensation photodiode are both electrically connected with a first voltage end, the second electrode of the compensation photodiode is electrically connected with the first electrode of the compensation capacitor, and the second electrode of the photosensitive photodiode and the second electrode of the compensation capacitor are both electrically connected to a signal output end;

the compensation photodiode is used for generating a leakage current equal to that of the photosensitive photodiode.

2. The photo-sensing circuit structure of claim 1, further comprising a control unit, wherein a first terminal of the control unit is electrically connected to the second terminal of the photo-sensing photodiode and the second terminal of the compensation capacitor, a second terminal of the control unit is electrically connected to the signal output terminal, and a control terminal of the control unit is electrically connected to the control signal terminal.

3. The light sensing circuit structure of claim 2, further comprising a reset unit, wherein a first terminal of the reset unit is electrically connected to a second voltage terminal, a second terminal of the reset unit is electrically connected to the second electrode of the photo diode and the second electrode of the compensation capacitor, and a control terminal of the reset unit is electrically connected to a reset signal terminal.

4. The light sensing circuit structure of claim 3, wherein the reset unit comprises at least two reset transistors connected in series, the at least two reset transistors comprising a first reset transistor and a second reset transistor, a first pole of the first reset transistor being electrically connected to the second voltage terminal and forming a first terminal of the reset unit, a second pole of the first reset transistor being electrically connected to a first pole of the second reset transistor, a second pole of the second reset transistor being electrically connected to a second pole of the light sensing photodiode and a second pole of the compensation capacitor and forming a second terminal of the reset unit;

and the control electrode of the first reset transistor and the control electrode of the second reset transistor are electrically connected with the reset signal end and form a control end of the reset unit.

5. The light sensing circuit structure of claim 4, further comprising an amplifying unit including an amplifying transistor, a first electrode of the amplifying transistor being electrically connected to the second voltage terminal, a second electrode of the amplifying transistor being electrically connected to a first terminal of the control unit, a control electrode of the amplifying transistor being electrically connected to the second electrode of the light sensing photodiode, the second electrode of the compensation capacitor, and a second terminal of the reset unit.

6. The photosensitive circuit structure of claim 5, further comprising an auxiliary transistor, a first pole of the auxiliary transistor electrically connected to the second pole of the photosensitive photodiode and the second pole of the compensation capacitor, a second pole of the auxiliary transistor electrically connected to the control pole of the amplifying transistor, and a control pole of the auxiliary transistor electrically connected to the control signal terminal.

7. A light sensing circuit arrangement according to any of claims 2-6, wherein the control unit comprises at least two control transistors connected in series, the at least two control transistors comprising a first control transistor and a second control transistor, a first pole of the first control transistor forming a first terminal of the control unit, a second pole of the first control transistor electrically connected to a first pole of the second control transistor, a second pole of the second control transistor electrically connected to the signal output and forming a second terminal of the control unit, a control pole of the first control transistor and a control pole of the second control transistor both electrically connected to the control signal terminal and forming a control terminal of the control unit.

8. A light sensing circuit structure as claimed in any one of claims 1 to 6, wherein the light sensing photodiode is located on the light incident side of the compensation photodiode.

9. A light sensing circuit structure according to any one of claims 1 to 6, comprising a substrate, wherein the light sensing photodiode and the compensation photodiode are both located on the substrate, an orthogonal projection of the light sensing photodiode on the substrate and an orthogonal projection of the compensation photodiode on the substrate do not overlap, and a light blocking member is disposed on a light incident side of the compensation photodiode.

10. An image sensor comprising the light sensing circuit structure of any one of claims 1 to 9.

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