Optical sensor, image sensor, and method for manufacturing optical sensor

Abstract

The embodiment of the invention provides an optical sensor, an image sensor and a manufacturing method of the optical sensor. The optical sensor comprises a first photosensitive module, a second photosensitive module and a control module, the first photosensitive module is used for receiving an optical signal and converting the optical signal into a first electric signal; the intensity of the first electric signal is positively correlated with the intensity of the optical signal; the second photosensitive module is used for receiving the optical signal in the on state and converting the optical signal into a second electric signal; the second photosensitive module stops converting the optical signal in a closed state; wherein the second electric signal is used for indicating the intensity of the optical signal; the control module is connected with the first photosensitive module and the second photosensitive module and used for controlling the second photosensitive module to be in a closed state when the intensity of the first electric signal is larger than or equal to a preset threshold value and controlling the second photosensitive module to be in an open state when the intensity of the first electric signal is smaller than the preset threshold value.

Description

Technical Field

[0001] Embodiments of the present application relate to the field of semiconductor technology, and in particular, to an optical sensor, an image sensor, and a method for manufacturing an optical sensor. Background Art

[0002] Devices based on the photoelectric effect, such as photodiodes, have the characteristics of high sensitivity, fast response and low noise, and are widely used in optical communications, photoelectric measurement, and photoelectric imaging.

[0003] When these devices work under high light intensity, the photocurrent in the device is likely to be too large, even exceeding the device's tolerance limit, causing damage to the device itself. Moreover, such damage is irreversible, seriously reducing the service life of the photoelectric effect device. Summary of the invention

[0004] In view of this, embodiments of the present application provide an optical sensor, a method for manufacturing the optical sensor, and an image sensor.

[0005] To achieve the above purpose, the technical solution of the embodiment of the present application is implemented as follows:

[0006] The embodiment of the present application provides an optical sensor, comprising: a first photosensitive module, a second photosensitive module and a control module;

[0007] The first photosensitive module is used to receive a light signal and convert the light signal into a first electrical signal; the intensity of the first electrical signal is positively correlated with the intensity of the light signal;

[0008] The second photosensitive module is used to receive the light signal in the on state and convert the light signal into a second electrical signal; the second photosensitive module stops converting the light signal in the off state; wherein the second electrical signal is used to indicate the intensity of the light signal;

[0009] The control module is connected to the first photosensitive module and the second photosensitive module, and is used to control the second photosensitive module to be in the closed state when the intensity of the first electrical signal is greater than or equal to a preset threshold, and to control the second photosensitive module to be in the open state when the intensity of the first electrical signal is less than the preset threshold.

[0010] In some embodiments, the maximum value of the photosensitivity of the first photosensitive module is greater than the maximum value of the photosensitivity of the second photosensitive module.

[0011] In some embodiments, the first photosensitive module includes at least one first diode, and the second photosensitive module includes at least one second diode;

[0012] The maximum photocurrent of the first diode is greater than the maximum photocurrent of the second diode.

[0013] In some embodiments, the first electrical signal is a current signal, and the preset threshold comprises a preset voltage;

[0014] The control module comprises:

[0015] a conversion unit, connected to the first diode, and configured to convert the current signal into a voltage signal;

[0016] A switch unit is connected to the conversion unit and is used to be turned on when the voltage signal is greater than or equal to the preset voltage to control the second photosensitive module to be in the off state, and to be turned off when the voltage signal is less than the preset voltage to control the second photosensitive module to be in the on state.

[0017] In some embodiments, the first photosensitive module includes one or more of the first diodes;

[0018] The conversion unit includes one or more capacitors; the number of the capacitors is the same as the number of the first diodes, and the first end of each of the capacitors is connected to one of the first diodes respectively;

[0019] The switch unit comprises one or a plurality of cascaded transistors; the number of the transistors is the same as the number of the first diodes, and the control end of each of the transistors is respectively connected to the second end of one of the capacitors;

[0020] Any of the transistors is used to be turned on when the voltage signal is greater than or equal to the preset voltage, so as to control the second photosensitive module to be in the off state.

[0021] In some embodiments, the photosensitive area of ​​the first diode is greater than the photosensitive area of ​​the second diode; and / or the thickness of the first diode is greater than the thickness of the second diode.

[0022] In some embodiments, the first diode includes at least one of a silicon photodiode, a germanium photodiode, an indium gallium arsenide diode, or a silicon carbide diode.

[0023] In some embodiments, the first photosensitive module further includes a microlens;

[0024] The microlens is located on a side of the first diode close to the light source and is used to gather light to the first diode.

[0025] In some embodiments, the first photosensitive module further includes a filtering element;

[0026] The filtering element is located on a side of the first diode close to the light source and is used to filter out optical signals outside the target wavelength range;

[0027] The first diode is used to convert the optical signal within the target wavelength range into the first electrical signal.

[0028] In some embodiments, the filter element includes a visible light filter; and / or an invisible light filter.

[0029] In a second aspect, an embodiment of the present application further provides an image sensor, comprising the above-mentioned optical sensor;

[0030] The analog-to-digital conversion circuit is used to convert the second electrical signal output by the second photosensitive module into a digital image signal.

[0031] In a third aspect, an embodiment of the present application further provides a method for manufacturing an optical sensor, comprising:

[0032] Providing a substrate; the substrate comprises a first region, a second region and a third region;

[0033] forming a gate structure of a transistor in the first region of the substrate;

[0034] forming a source and a drain of the transistor in the first region;

[0035] A first diode is formed in the second region and a second diode is formed in the third region respectively; a maximum photocurrent of the first diode is greater than a maximum photocurrent of the second diode;

[0036] forming a capacitor structure on the first diode, wherein the first diode is coupled to the gate structure of the transistor through the capacitor structure;

[0037] An optical component is formed on a side of the capacitor structure away from the substrate; or the substrate is flipped over to form an optical component on a side of the substrate away from the capacitor structure; wherein a projection of the optical component on the substrate covers a projection of the first diode on the substrate.

[0038] The optical sensor provided in the embodiment of the present application includes a first photosensitive module, a second photosensitive module and a control module. When the first electrical signal output by the first photosensitive module is less than a preset threshold value, the intensity of the light signal will not damage the second photosensitive module, and the control module controls the second photosensitive module to turn on and work. When the first electrical signal output by the first photosensitive module is greater than or equal to the preset threshold value, the intensity of the light signal is relatively large, and the risk of damage to the second photosensitive module when working under this condition is relatively high. The control module controls the second photosensitive module to be in a closed state, which can prevent the second photosensitive module from working under the condition of a high-intensity light signal, reduce the risk of damage to the second photosensitive module, and effectively extend the service life of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of the structure of the optical sensor provided in the embodiment of the present application Figure 1 ;

[0040] Figure 2 Schematic diagram of the structure of the optical sensor provided in the embodiment of the present application Figure 2 ;

[0041] Figure 3 Schematic diagram of the circuit principle of the optical sensor provided in the embodiment of the present application Figure 1 ;

[0042] Figure 4 Schematic diagram of the circuit principle of the optical sensor provided in the embodiment of the present application Figure 2 ;

[0043] Figure 5 A schematic diagram of the structure of an image sensor provided in an embodiment of the present application;

[0044] Figure 6 A schematic diagram of the steps for manufacturing an optical sensor provided in an embodiment of the present application;

[0045] FIG. 7A to FIG. 7B A front view and a top view of an intermediate structure for manufacturing an optical sensor provided in an embodiment of the present application;

[0046] Figures 8 to 11 Schematic diagram of the intermediate structure of the optical sensor provided in the embodiment of the present application Figures 1 to 4 ;

[0047] Figure 12 to Figure 14 Schematic diagram of the optical sensor structure provided in the embodiment of the present application Figures 1 to 3 . DETAILED DESCRIPTION

[0048] The following will be combined with the embodiments of the present application and the accompanying drawings to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0049] In the following description, a large number of specific details are given to provide a more thorough understanding of the present application. However, it is obvious to those skilled in the art that the present application can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present application, some technical features known in the art are not described; that is, all features of the actual embodiments are not described here, and well-known functions and structures are not described in detail.

[0050] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present application. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0051] In order to thoroughly understand the present application, detailed steps and detailed structures will be presented in the following description to illustrate the technical solution of the present application. The preferred embodiments of the present application are described in detail below, but in addition to these detailed descriptions, the present application may also have other implementation methods.

[0052] The photoelectric effect refers to the fact that when light shines on the surface of certain devices, electron-hole pairs are excited inside the device, thereby generating current. Devices based on the photoelectric effect have been widely used in solar cells, photoelectric detection and other fields.

[0053] However, excessive light intensity may affect the working performance of the photoelectric effect device and may even cause irreversible damage to the photoelectric effect device. For example, excessive light intensity may cause the device to overheat, leading to device damage. In addition, long-term high current may accelerate device aging and shorten the service life of the photoelectric effect device.

[0054] In view of this, an embodiment of the present application provides an optical sensor, such as Figure 1As shown, the optical sensor 100 includes: a first photosensitive module 101, a second photosensitive module 102 and a control module 103;

[0055] The first photosensitive module 101 is used to receive the optical signal and convert the optical signal into a first electrical signal; the intensity of the first electrical signal is positively correlated with the intensity of the optical signal;

[0056] The second photosensitive module 102 is used to receive the light signal in the on state and convert the light signal into a second electrical signal; the second photosensitive module 102 stops converting the light signal in the off state; wherein the second electrical signal is used to indicate the intensity of the light signal;

[0057] The control module 103 is connected to the first photosensitive module 101 and the second photosensitive module 102, and is used to control the second photosensitive module 102 to be in an off state when the intensity of the first electrical signal is greater than or equal to a preset threshold, and to control the second photosensitive module 102 to be in an on state when the intensity of the first electrical signal is less than the preset threshold.

[0058] The first photosensitive module 101 and the second photosensitive module 102 are both photosensitive modules based on the photoelectric effect. They can both receive light signals, stimulate electron-hole pairs through photons, and generate electrical signals. The intensity of the light signal (abbreviated as light intensity) refers to the amount of energy received per unit area per unit time. The greater the light intensity, the greater the first electrical signal output by the first photosensitive module 101.

[0059] When the first electrical signal received by the control module 103 is too large, greater than or equal to the preset threshold, it is considered that the intensity of the light signal received by the first photosensitive module 101 is too large, that is, the light intensity in the environment is too large. Since the intensity of the light signal or the second electrical signal that the second photosensitive module 102 can withstand in the turned-on state is limited, the light signal or the second electrical signal with too large intensity may cause the second photosensitive module 102 in the turned-on state to have a significant thermal effect, the material of the second photosensitive module 102 to melt, and then cause irreversible damage to the second photosensitive module 102. Therefore, the control module 103 controls the second photosensitive module 102 to be in the turned-off state, so as to avoid the second photosensitive module 102 in the turned-on state from having a significant thermal effect, and reduce the risk of the material of the second photosensitive module 102 to be melted and damaged.

[0060] When the first electrical signal received by the control module 103 is less than the preset threshold, it is considered that the second photosensitive module 102 in the on state can work or continue to work under the light intensity. The control module 103 controls the second photosensitive module 102 to be in the on state, so that the second photosensitive module 102 converts the light signal into a second electrical signal in the on state.

[0061] The optical sensor 100 provided in the embodiment of the present application converts the optical signal into a first electrical signal through the first photosensitive module 101. When the intensity of the first electrical signal is greater than or equal to the preset threshold, it is considered that the intensity of the optical signal is greater than or equal to the conversion or tolerance limit of the second photosensitive module 102, which may cause damage to the second photosensitive module 102. The control module 103 controls the second photosensitive module 102 to be in a closed state to avoid obvious thermal effects on the second photosensitive module 102 in the open state, thereby reducing the risk of material melting damage to the second photosensitive module 102. When the intensity of the first electrical signal is less than the preset threshold, it is considered that the intensity of the optical signal will not cause damage to the second module 102 in the open state, and the second photosensitive module 102 is controlled to be in an open state, and the received optical signal is converted into a second electrical signal.

[0062] In some embodiments, the maximum value of the photosensitivity of the first photosensitive module 101 is greater than the maximum value of the photosensitivity of the second photosensitive module 102 .

[0063] The first photosensitive module 101 converts the light signal into a first electrical signal, and the intensity of the first electrical signal is positively correlated with the intensity of the light signal. That is, the greater the light intensity, the greater the intensity of the first electrical signal output by the first photosensitive module 101. However, when the light intensity increases to a certain value, the first electrical signal no longer increases with the increase of the light intensity, but reaches a saturation value. The minimum light intensity corresponding to this saturation value is the maximum photosensitivity of the first photosensitive module 101. When the light intensity is greater than the maximum photosensitivity of the first photosensitive module 101, that is, when the light intensity is greater than the maximum value of the photosensitivity of the first photosensitive module 101, the risk of damage to the first photosensitive module 101 increases sharply. Similarly, when the light intensity is greater than the maximum value of the photosensitivity of the second photosensitive module 102, the risk of damage to the second photosensitive module 102 will also increase sharply.

[0064] Since the maximum value of the photosensitivity of the first photosensitive module 101 is greater than the maximum value of the photosensitivity of the second photosensitive module 102, the intensity of the light signal in the environment can be first detected by the first photosensitive module 101 that can convert or withstand light signals of greater intensity. When the detected light intensity is greater than or equal to the intensity threshold (for example, the maximum photosensitivity of the second photosensitive module 102), it is considered that the intensity of the light signal is greater than or equal to the light intensity corresponding to the conversion or tolerance limit of the second photosensitive module 102, which may cause damage to the second photosensitive module 102. The control module 103 controls the second photosensitive module 102 to shut down, so as to prevent the second photosensitive module 102 from working in a high-intensity light environment and reduce the risk of damage to the second photosensitive module 102.

[0065] Of course, it is understandable that in order to further reduce the risk of damage to the second photosensitive module 102 , the intensity threshold may be set to be less than the maximum photosensitivity intensity of the second photosensitive module 102 .

[0066] In some embodiments, the first photosensitive module 101 includes at least one first diode D1, and the second photosensitive module 102 includes at least one second diode D2;

[0067] The maximum photocurrent of the first diode D1 is greater than the maximum photocurrent of the second diode D2.

[0068] The first diode D1 and the second diode D2 are both semiconductor PN junction devices that convert light signals into current. For example, the first diode D1 and the second diode D2 are both photodiodes. Specifically, when light is irradiated onto the PN junction of the photodiode, photons hit the photodiode, and the photons are absorbed and excited to generate electron-hole pairs. The holes and electrons in the depletion region move toward the anode and cathode, respectively, generating photocurrent. However, excessive light intensity will affect the working performance of the photodiode. On the one hand, excessive light intensity may cause the photodiode to be saturated, or even exceed the working range of the second photosensitive module 102, affecting the normal operation of the second photosensitive module 102. For example, when the light intensity exceeds the normal working range of the image sensor, it will directly affect the imaging quality of the image sensor. On the other hand, excessive light intensity may cause the photodiode to overheat, thereby causing damage to the device. Furthermore, the passage of large current for a long time will also accelerate the aging of the photodiode and shorten the service life of the photodiode.

[0069] The maximum photocurrent of a photodiode (first diode D1 or second diode D2) refers to the maximum current that the photodiode itself can withstand, that is, the maximum allowable current. When the current passing through the photodiode exceeds the maximum allowable current, the photodiode may be burned out. Under the same high-intensity light condition, since the maximum photocurrent of the first diode D1 is greater than the maximum photocurrent of the second diode D2, the first diode D1 can work normally and convert the optical signal into the first electrical signal, while the second diode D2 is easily burned out.

[0070] In some embodiments, when the second photosensitive module 102 is in the on state, a reverse bias voltage is connected across the second diode D2, and the second diode D2 under the reverse bias condition can convert the received light signal into a corresponding second electrical signal within a shorter response time. When the second photosensitive module 102 is in the off state, a photocurrent is also generated across the second diode D2. However, under the same light intensity conditions, the photocurrent of the second diode D2 in the off state is much smaller than the photocurrent of the second diode in the on state.

[0071] In some embodiments, the first electrical signal is a current signal, and the preset threshold value includes a preset voltage;

[0072] like Figure 2 As shown, the control module 103 includes:

[0073] The conversion unit 401 is connected to the first diode D1 and is used to convert the current signal into a voltage signal;

[0074] The switch unit 402 is connected to the conversion unit 401 and is used to be turned on when the voltage signal is greater than or equal to the preset voltage to control the second photosensitive module 102 to be in an off state, and to be turned off when the voltage signal is less than the preset voltage to control the second photosensitive module 102 to be in an on state.

[0075] The first photosensitive module 101 receives the light signal and outputs a first electrical signal (current signal) corresponding to the light intensity. The conversion unit 401 connected to the first diode D1 converts the first electrical signal into a corresponding voltage signal. When the voltage signal is greater than or equal to the preset voltage, that is, the intensity of the first electrical signal is greater than or equal to the preset threshold, it is considered that the intensity of the light signal is greater than or equal to the tolerance limit of the second photosensitive module 102. The control module 103 controls the second photosensitive module 102 to be in a closed state to reduce the risk of damage to the second diode D2 or the second photosensitive module 102. When the voltage signal is less than the preset voltage, that is, the intensity of the first electrical signal is less than the preset threshold, it is considered that the intensity of the light signal will not cause damage to the second diode D2 or the second module 102 in the open state, and the second photosensitive module 102 is controlled to be in the open state, and the second photosensitive module 102 works normally to convert the received light signal into a second electrical signal.

[0076] In some embodiments, the first photosensitive module 101 includes one or more first diodes D1;

[0077] The conversion unit 401 includes one or more capacitors C; the number of the capacitors C is the same as the number of the first diodes D1, and the first end of each capacitor C is connected to a first diode D1;

[0078] The switch unit 402 includes one or more cascaded transistors M; the number of the transistors M is the same as the number of the first diodes D1, and the control end of each transistor M is connected to the second end of a capacitor C respectively;

[0079] Any transistor M is used to be turned on when the voltage signal is greater than or equal to a preset voltage, so as to control the second photosensitive module 102 to be in a closed state.

[0080] In a specific embodiment, if Figure 3As shown, the first photosensitive module 101 includes three first diodes D1, which are respectively connected to the first ends of three capacitors C. The second ends of the three capacitors C are respectively connected to the control ends (gates) of three transistors M connected in series. When the intensity of the first electrical signal output by any first diode D1 in the first photosensitive module 101 is greater than or equal to a preset threshold, the transistor M coupled to the first diode D1 is turned on. It is possible to detect whether there is a conduction loop between the A1 terminal and the A2 terminal, between the A2 terminal and the A3 terminal, or between the A3 terminal and the A4 terminal, and control the second photosensitive module 102 to be in a closed state when there is a conduction loop.

[0081] In another specific embodiment, Figure 4 As shown, the first photosensitive module 101 includes three first diodes D1, which are respectively connected to the first ends of three capacitors C. The second ends of the three capacitors C are respectively connected to the control ends (gates) of three transistors M, wherein the three transistors M are connected in parallel between the B1 end and the B2 end. When the intensity of the first electrical signal output by any first diode D1 in the first photosensitive module 101 is greater than or equal to the preset threshold, the transistor M coupled to the first diode D1 is turned on, and the second photosensitive module 102 can be controlled to be in a closed state by judging whether the B1 end and the B2 end are turned on.

[0082] It should be noted that the embodiment of the present application does not limit the specific number of the first diodes D1, which can be selected and set according to actual needs.

[0083] In some embodiments, the photosensitive area of ​​the first diode D1 is greater than the photosensitive area of ​​the second diode D2; and / or the thickness of the first diode D1 is greater than the thickness of the second diode D2.

[0084] The photosensitive area refers to the area of ​​the photodiode that can receive light signals and convert them into corresponding electrical signals. The larger the photosensitive area, the more photons the photodiode can absorb, which in turn can stimulate more hole-electron pairs and generate a larger photocurrent.

[0085] The thickness of the first diode D1 and the second diode D2 refers to the thickness of their depletion regions. On the basis of other conditions being the same, for example, when the reverse bias voltage is consistent, the thickness of the depletion region of the first diode D1 is greater than the thickness of the depletion region of the second diode D2.

[0086] In addition, it should be noted that the maximum current that the second diode D2 can convert or withstand can be increased by increasing the photosensitive area and / or thickness of the second diode D2. However, for the second photosensitive module 102 having a plurality of second diodes D2 arranged in an array, increasing the photosensitive area and / or thickness of the second diode D2 is not only not conducive to the miniaturization of the optical sensor 100, but also reduces the response speed of the second photosensitive module 102.

[0087] In some embodiments, the first diode D1 includes at least one of a silicon photodiode, a germanium photodiode, an indium gallium arsenide diode, or a silicon carbide diode.

[0088] Among them, silicon photodiodes are more sensitive to visible light; germanium photodiodes and indium gallium arsenide diodes are more sensitive to infrared rays; and silicon carbide diodes are more sensitive to ultraviolet rays.

[0089] In some embodiments, the second diode D2 includes at least one of a silicon photodiode, a germanium photodiode, an indium gallium arsenide diode, or a silicon carbide diode. It should be noted that the first diode D1 and the second diode D2 can be the same type of photodiode. For example, the first diode D1 and the second diode D2 are both silicon photodiodes. The first diode D1 and the second diode D2 can also be different types of photodiodes. For example, the first diode D1 is a silicon photodiode, and the second diode D2 is an indium gallium arsenide diode. The embodiments of the present application do not limit the specific categories of the first diode D1 and the second diode D2, as long as the maximum light intensity that the first diode D1 can convert or withstand is greater than the maximum light intensity that the second diode D2 can convert or withstand.

[0090] In some embodiments, the first photosensitive module 101 further includes a microlens;

[0091] The micro lens is located on a side of the first diode D1 close to the light source, and is used to gather light to the first diode D1.

[0092] The microlens can change the incident angle of light, so that light that cannot directly irradiate the first diode D1 is focused on the first diode D1, which is equivalent to increasing the photosensitive area of ​​the first diode D1 and improving the photoelectric conversion efficiency of the first diode D1.

[0093] In some embodiments, a microlens for collecting light may be disposed on a side of the second diode D2 close to the light source to improve the photoelectric conversion efficiency of the second diode D2.

[0094] In some embodiments, the first photosensitive module 101 further includes a filter element;

[0095] The filter element is located on the side of the first diode D1 close to the light source and is used to filter out the optical signal outside the target wavelength range;

[0096] The first diode D1 is used to convert an optical signal within a target wavelength range into a first electrical signal.

[0097] On the one hand, the filter element can allow optical signals with wavelengths within the target range to pass through, while absorbing or reflecting optical signals with other wavelengths. On the other hand, since the filter element can filter out optical signals outside the target range, it can also protect the first diode D1 from being damaged by high-intensity optical signals with other wavelengths.

[0098] In some embodiments, the filter element includes a visible light filter; and / or, an invisible light filter.

[0099] Visible light filters are filters that allow visible light within a target wavelength range to pass through by absorbing or reflecting light signals within an unwanted wavelength range. For example, a red filter, a green filter, or a blue filter. Similarly, invisible light filters allow invisible light within a target wavelength range to pass through. For example, an infrared filter or a UV filter.

[0100] It should be noted that, in the first photosensitive module 101 including a plurality of first diodes D1, a filter can be disposed above each first diode D1 to filter out light signals outside the target wavelength range corresponding to the filter. Furthermore, the filters on different first diodes D1 can be different filters. Exemplarily, in a specific embodiment, a red filter, a green filter, and a blue filter are disposed on the three first diodes D1, respectively. In another specific embodiment, a red filter, a green filter, a blue filter, and an infrared filter are disposed on the four first diodes D1, respectively.

[0101] Based on the same inventive concept, the embodiment of the present application also provides an image sensor, such as Figure 5 As shown, the image sensor 200 includes the above-mentioned optical sensor 100;

[0102] The analog-to-digital conversion circuit 201 is used to convert the second electrical signal output by the second photosensitive module 102 into a digital image signal.

[0103] When the first photosensitive module 101 receives a light signal with a relatively high intensity, the intensity of the first electrical signal is greater than or equal to the preset threshold, and the second photosensitive module 102 is controlled to be in an off state. When the first electrical signal is less than the preset threshold, the second photosensitive module 102 is controlled to be in an on state. When the second photosensitive module 102 is in the on state, the received light signal is converted into a second electrical signal. The analog-to-digital conversion circuit converts the second electrical signal output by the second photosensitive module 102 into a digital image signal and then outputs it.

[0104] In some embodiments, the second photosensitive module 102 includes a plurality of second diodes D2 arranged in an array. The second diode D2 converts the received light signal into a second electrical signal corresponding to the pixel. When the second photosensitive module 102 is in an on state, a reverse bias voltage is connected to both ends of the second diode D2. When the second photosensitive module 102 is in an off state, the second diode D2 is zero biased. At this time, a photocurrent may also be generated at both ends of the second diode D2. However, the analog-to-digital conversion circuit in the image sensor will not further process the photocurrent generated in this off state.

[0105] In some embodiments, the second diode D2 in the image sensor can receive and convert light signals within the visible light range. In this case, a red filter, a green filter, and a blue filter can be respectively arranged above the plurality of first diodes D1 and the plurality of second diodes D2. Among them, the first diodes D1 corresponding to each filter in the first photosensitive module 101 are respectively used to detect the intensity of each color light signal; the second diodes D2 corresponding to each filter in the second photosensitive module 102 are respectively used to convert the light signals of the three colors of red, green, and blue into corresponding second electrical signals, so as to generate a color image.

[0106] In some other embodiments, the second diode D2 in the image sensor can receive and convert infrared light or ultraviolet light, for example, an infrared image sensor or an ultraviolet image sensor.

[0107] Based on the same inventive concept, the present application also provides a method for manufacturing an optical sensor, such as Figure 6 As shown, the manufacturing method comprises the following steps:

[0108] Step S101: providing a substrate; the substrate includes a first region, a second region and a third region.

[0109] Step S102: forming a gate structure of a transistor in a first region of the substrate.

[0110] Step S103: forming a source and a drain of a transistor in the first region.

[0111] Step S104: forming a first diode in the second region and a second diode in the third region; the maximum photocurrent of the first diode is greater than the maximum photocurrent of the second diode.

[0112] Step S105: forming a capacitor structure on the first diode, and the first diode is coupled to the gate structure of the transistor through the capacitor structure.

[0113] Step S106: forming an optical component on a side of the capacitor structure away from the substrate; or flipping the substrate to form an optical component on a side of the substrate away from the capacitor structure; wherein the projection of the optical component on the substrate covers the projection of the first diode on the substrate.

[0114] By forming the source, drain and gate structure of the transistor on the first area of ​​the substrate, forming the first diode and the capacitor structure in the second area, and the second diode in the third area, an optical sensor in which the maximum photocurrent of the first diode is greater than the maximum photocurrent of the second diode can be obtained. Since the maximum photocurrent of the first diode is greater than the maximum photocurrent of the second diode, the maximum intensity of the optical signal that the first diode can convert or withstand is greater than the maximum intensity of the optical signal that the second diode can convert or withstand. By allowing the first diode to receive and convert the optical signal. When the intensity of the optical signal is too large, the transistor coupled to it through the capacitor structure is turned on, and the second diode in the third area can be controlled to be in an off state. In this way, the second diode can be prevented from being damaged when working in a high-intensity light environment. When the intensity of the optical signal is within a certain range, the transistor coupled to it through the capacitor structure is turned off, and the second diode in the third area can be controlled to be in an on state.

[0115] In some embodiments, a reverse bias voltage is connected to both ends of the second diode in the on state, and the second diode under the reverse bias condition can convert the received optical signal into a corresponding electrical signal in a shorter response time. In addition, it should be noted that the second diode in the off state may also generate a photocurrent. However, under the same light intensity conditions, the photocurrent of the second diode in the off state is much smaller than the photocurrent of the second diode in the on state.

[0116] In a specific embodiment, if Fig. 7A As shown, a substrate 700 is provided. Figure 7B As shown, the substrate 700 includes a first region 701, a second region 702 and a third region 703. The above three regions do not overlap each other. It should be noted that the embodiment of the present application does not limit the size and relative position of each region. The first region 701 and the second region 702 can be arranged to surround the third region 703.

[0117] like Figure 8 As shown, a gate structure 801 of a transistor M is formed in the first region 701 of the substrate 700, specifically including a stacked gate dielectric layer and a gate layer (not shown in the figure). The threshold voltage Vth of the transistor M is the above-mentioned preset threshold, which can be obtained by adjusting the thickness of the gate dielectric layer and / or the doping concentration of the source and drain. In addition, the light intensity corresponding to the threshold voltage Vth of the transistor M is the maximum light intensity that the second diode can withstand.

[0118] like Fig. 9 As shown, by using an ion implantation process, a source 901a and a drain 901b of the transistor are formed on both sides of the gate structure 701 in the first region 701. It should be noted that the positions of the source 901a and the drain 901b can be interchanged.

[0119] like Fig.10 As shown, through an ion implantation process, one or more first diodes 1001 are formed in the second region 802 and one or more second diodes 1002 are formed in the third region.

[0120] It should be noted that the embodiment of the present application does not limit the relative order of forming the first diode 1001 and forming the second diode 1002. The first diode 1001 may be formed in the second region 702 before forming the second diode 1002 in the third region 703; the second diode 1002 may be formed in the third region 703 before forming the first diode 1001 in the second region 702. In addition, the embodiment of the present application does not limit the relative order of forming the transistor source and drain and forming the first diode or the second diode. That is, the above step S104 may also be performed before the execution of step S103.

[0121] like Fig.11 As shown, a capacitor structure 1101 is formed on the first diode 1001. It is understandable that in the process of forming the capacitor structure 1101, a related metal interconnect structure can be formed simultaneously, so that one side of the capacitor structure 1101 is connected to one end of the first diode D1, and the other side of the capacitor structure 1101 is connected to the gate 801 of the transistor.

[0122] In one embodiment, if Fig.12 As shown, after the capacitor structure 1101 is formed, an optical component 1201 is formed on a side of the capacitor structure 1101 away from the substrate.

[0123] In some embodiments, the optical component includes a microlens and / or a filtering element.

[0124] In a specific embodiment, in the above step S106, forming an optical component on the side of the capacitor structure away from the substrate specifically includes: forming a filter element on the side of the capacitor structure away from the substrate; forming a microlens on the side of the filter element away from the substrate.

[0125] like Fig.13As shown, a filter element 1302 (including a red filter 1302a, a green filter 1302b and a blue filter 1302c) is formed on the side of the capacitor structure 1101 away from the substrate 700. A microlens 1301 is formed on the side of the filter element 1302 away from the substrate 700. The red filter 1302a, the green filter 1302b and the blue filter 1302c correspond to the three first diodes one by one. The orthographic projection of each filter on the substrate 700 overlaps with the orthographic projection of the corresponding first diode on the substrate 700.

[0126] Continue to refer to Fig.13 , an isolation member 1303 is also provided between each filter. The isolation member 1303 can be a metal material or a black material, and is used to achieve optical isolation and prevent optical crosstalk between different filters. In addition, in the present embodiment, a plurality of transistors connected in series are formed in the first region 701. The number of transistors (the number of gate structures) is the same as the number of first diodes in the second region. The three first diodes are respectively coupled to the gates of the three transistors in the first region through three capacitors. Among them, the source and drain of the three transistors are shared. That is, the source / drain of the first transistor on the left can be used as the drain / source of the middle transistor.

[0127] In another specific embodiment, in the above step S106, the substrate is flipped over to form an optical component on a side of the substrate away from the capacitor structure, specifically including: forming a filter element on a side of the substrate away from the capacitor structure; forming a microlens on a side of the filter element away from the substrate.

[0128] like Fig.14 As shown, after the capacitor structure 1101 is formed, the substrate 700 is flipped so that the side of the substrate 700 away from the capacitor structure 1101 faces upward. In addition, an optical component 1201 is formed on the side of the substrate 700 away from the capacitor structure 1101. Fig.13 In the optical sensor shown, the optical component is arranged on the side of the substrate away from the capacitor structure 1101, so that the metal in the capacitor structure 1101 is away from the incident light, which can further reduce the light crosstalk problem caused by the reflection of the incident light in the capacitor structure 1101. It can be understood that the optical component 1201 in this embodiment can also include a microlens 1301, a filter element 1302 and an isolation member 1303.

[0129] The various embodiments / implementations provided in this application can be combined with each other without causing any contradiction.

[0130] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An optical sensor, characterized in that: include: A first photosensitive module, a second photosensitive module and a control module; The first photosensitive module is used to receive a light signal and convert the light signal into a first electrical signal; the intensity of the first electrical signal is positively correlated with the intensity of the light signal; The second photosensitive module is used to receive the light signal in the turned-on state and convert the light signal into a second electrical signal; the second photosensitive module stops converting the light signal in the turned-off state; wherein the second electrical signal is used to indicate the intensity of the light signal; The control module is connected to the first photosensitive module and the second photosensitive module, and is used to control the second photosensitive module to be in the closed state when the intensity of the first electrical signal is greater than or equal to a preset threshold, and to control the second photosensitive module to be in the open state when the intensity of the first electrical signal is less than the preset threshold.

2. The optical sensor according to claim 1, characterized in that The maximum value of the photosensitivity of the first photosensitive module is greater than the maximum value of the photosensitivity of the second photosensitive module.

3. The optical sensor according to claim 2, characterized in that The first photosensitive module includes at least one first diode, and the second photosensitive module includes at least one second diode; The maximum photocurrent of the first diode is greater than the maximum photocurrent of the second diode.

4. The optical sensor according to claim 3, characterized in that The first electrical signal is a current signal, and the preset threshold value includes a preset voltage; The control module comprises: a conversion unit, connected to the first diode, and configured to convert the current signal into a voltage signal; A switch unit is connected to the conversion unit and is used to be turned on when the voltage signal is greater than or equal to the preset voltage to control the second photosensitive module to be in the off state, and to be turned off when the voltage signal is less than the preset voltage to control the second photosensitive module to be in the on state.

5. The optical sensor according to claim 4, characterized in that The first photosensitive module includes one or more of the first diodes; The conversion unit includes one or more capacitors; the number of the capacitors is the same as the number of the first diodes, and the first end of each of the capacitors is connected to one of the first diodes respectively; The switch unit comprises one or a plurality of cascaded transistors; the number of the transistors is the same as the number of the first diodes, and the control end of each of the transistors is respectively connected to the second end of one of the capacitors; Any of the transistors is used to be turned on when the voltage signal is greater than or equal to the preset voltage, so as to control the second photosensitive module to be in the off state.

6. The optical sensor according to claim 3, characterized in that The photosensitive area of ​​the first diode is greater than the photosensitive area of ​​the second diode; and / or the thickness of the first diode is greater than the thickness of the second diode.

7. The optical sensor according to claim 3, characterized in that The first diode includes at least one of a silicon photodiode, a germanium photodiode, an indium gallium arsenide diode or a silicon carbide diode.

8. The optical sensor according to claim 3, characterized in that The first photosensitive module also includes a microlens; The microlens is located on a side of the first diode close to the light source and is used to gather light to the first diode.

9. The optical sensor according to claim 3, characterized in that: The first photosensitive module also includes a filter element; The filtering element is located on a side of the first diode close to the light source and is used to filter out optical signals outside the target wavelength range; The first diode is used to convert the optical signal within the target wavelength range into the first electrical signal.

10. The optical sensor according to claim 9, characterized in that The filter element includes a visible light filter; and / or an invisible light filter.

11. An image sensor, characterized in that: comprising an optical sensor as claimed in any one of claims 1 to 10; The analog-to-digital conversion circuit is used to convert the second electrical signal output by the second photosensitive module into a digital image signal.

12. A method for manufacturing an optical sensor, characterized in that: include: providing a substrate; The substrate includes a first region, a second region and a third region; forming a gate structure of a transistor in the first region of the substrate; forming a source and a drain of the transistor in the first region; A first diode is formed in the second region and a second diode is formed in the third region respectively; a maximum photocurrent of the first diode is greater than a maximum photocurrent of the second diode; forming a capacitor structure on the first diode, wherein the first diode is coupled to the gate structure of the transistor through the capacitor structure; An optical component is formed on a side of the capacitor structure away from the substrate; or the substrate is flipped over to form an optical component on a side of the substrate away from the capacitor structure; wherein a projection of the optical component on the substrate covers a projection of the first diode on the substrate.

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