Patent ID: 12225273

DETAILED DESCRIPTION

The embodiments are described in detail below with reference to the appended drawings to better understand the aspects of the present application. However, the provided embodiments are not intended to limit the scope of the disclosure, and the description of the structural operation is not intended to limit the order in which they are performed. Any device that has been recombined by components and produces an equivalent function is within the scope covered by the disclosure.

As used herein, “coupled” and “connected” may be used to indicate that two or more elements physical or electrical contact with each other directly or indirectly, and may also be used to indicate that two or more elements cooperate or interact with each other.

Referring toFIG.1,FIG.1is a sectional diagram of an image sensor100in accordance with some embodiments of the present disclosure. In some embodiments, the image sensor100is applied to some electronic imaging devices (e.g., camera, etc.), and is configured to sense light and convert the light into signals for forming images. In particular, the image sensor100can be a complementary metal oxide semiconductor (CMOS) sensor, etc. However, the present disclosure is not limited herein.

In some embodiments, as shown inFIG.1, the image sensor100includes a first transparent conductive layer10, a second conductive layer20, an optical sensor30, a semiconductor substrate40, a microlens layer50and a protection layer60. The optical sensor30is arranged between the first transparent conductive layer10and the second conductive layer20. The microlens layer50is over the first transparent conductive layer10, in which the microlens layer50includes at least one microlens51. The protection layer60is arranged between the microlens layer50and the first transparent conductive layer10, in which the protection layer60includes an oxide material (e.g., silicon oxide, aluminum oxide, etc.), a nitride material (e.g., silicon nitride, etc.), an oxynitride material (e.g., silicon oxynitride, etc.), a hydrogenated silicon (Si:H) or a combination thereof. The semiconductor substrate40is below the second conductive layer20, in which the semiconductor substrate40includes at least one pixel circuit41.

In some embodiments, as shown inFIG.1, the optical sensor30includes a photoelectric conversion layer31, a first carrier transporting layer33and a second carrier transporting layer35. The first carrier transporting layer33is arranged between the first transparent conductive layer10and the photoelectric conversion layer31, and the second carrier transporting layer35is arranged between the photoelectric conversion layer31and the second conductive layer20. In other words, the photoelectric conversion layer31is arranged between the first carrier transporting layer33and the second carrier transporting layer35. Furthermore, the first carrier transporting layer33and the second carrier transporting layer35are configured to be the hole transporting layer (HTL) and the electron transporting layer (ETL), respectively. That is, the first carrier transporting layer33is used to transport holes, and the second carrier transporting layer35is used to transport electrons.

In accordance with the above embodiments, the material of the first carrier transporting layer33includes inorganic materials, such as molybdenum trioxide (MoO3), Nickel(II) oxide (NiO), and tungsten trioxide (WO3), and/or organic materials, such as poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS). The first carrier transporting layer33has a thickness ranging from 1 to 200 nm. The material of the second carrier transporting layer35includes inorganic materials, such as zinc oxide (ZnO), and titanium dioxide (TiO2), and/or organic materials, such as buckyball (C60), [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), and fullerene derivatives. The second carrier transporting layer35has a thickness ranging from 1 to 200 nm. The photoelectric conversion layer31includes organic materials, quantum dot (QD) materials, perovskite materials or a combination thereof.

In some embodiments, the photoelectric conversion layer31is formed by using coating technology, such as blade coating, slot-die coating, etc. By controlling the coating parameters, such as coating speed, coating temperature, viscosity of the ink, gap between coating tip and substrate, and the number of times of the coating, the photoelectric conversion layer31being formed has a thickness T1ranging from 500 to 10000 nm. Notably, the image sensor100of the present disclosure can be switched among multiple operation modes through the photoelectric conversion layer31with the thickness T1. Some related arts use spin coating to form the photoelectric conversion layer. However, the photoelectric conversion layer formed by using spin coating cannot have such thickness like the photoelectric conversion layer31of the present disclosure has. Thus, the image sensor applying the photoelectric conversion layer formed by using spin coating cannot be switched among multiple operation modes.

Referring toFIG.2,FIG.2is a schematic diagram of an electronic imaging device200including the image sensor100, a multiplexer43and a processing circuit45in accordance with some embodiments of the present disclosure. In some embodiments, as shown inFIG.2, the pixel circuit41is implemented by a capacitive trans-impedance amplifier (CTIA), but the present disclosure is not limited herein. In the embodiments that the pixel circuit41is implemented by the CTIA, the pixel circuit41includes an amplifier A, a reset switch SW, and an integrating capacitor Cfb. The reset switch SW and the integrating capacitor Cfb are connected in parallel, and are then connected between a negative input terminal and an output terminal of the amplifier A. The inverted input terminal of the amplifier A is further connected to the second conductive layer20. In addition, a non-inverted input terminal of the amplifier A is configured to receive a reference voltage Vref.

In some embodiments, the multiplexer43is configured to apply a bias voltage Vbias to the image sensor100. As shown inFIG.2, the multiplexer43is electrically coupled to the first transparent conductive layer10. The multiplexer43is configured to receive a control signal Vc outputted by the processing circuit45, a first voltage input with voltage level V1and a second voltage input with voltage level V2, and is configured to choose one of the first and second voltage inputs as the bias voltage Vbias according to the control signal Vc. The bias voltage Vbias is then applied to the first transparent conductive layer10. The optical sensor30is configured to receive the bias voltage Vbias via the first transparent conductive layer10. Notably, the optical characteristic of the optical sensor30would changes with the voltage level of the bias voltage Vbias, which further results in different operation modes of the image sensor100. In the embodiments ofFIG.2, the first voltage level V1is different from the second voltage level V2. For example, the magnitude of the first voltage level V1(e.g., 0 V to −10 V, etc.) is smaller than the magnitude of the second voltage level V2(e.g., −10 V to −18 V, etc.). As a result, the image sensor100may be switched between two operation modes according to the voltage level of the bias voltage Vbias. For illustrative purpose, only the first voltage input with the first voltage level V1and the second voltage input with second voltage level V2are shown inFIG.2, but the present disclosure is not limited herein. In some embodiments, the multiplexer43receives more than two voltage inputs with different voltage levels, and the control signal Vc controls the multiplexer43to output one of the voltage inputs as the bias voltage Vbias, so that the bias voltage Vbias is controlled by the control signal Vc to have one of the different voltage levels. As such, the image sensor100may be operated in one of multiple operation modes respectively corresponding to the different voltage levels of the bias voltage Vbias.

Referring toFIG.3,FIG.3is a schematic diagram of multiple optical characteristics of the optical sensor30corresponding to the different voltage levels of the bias voltage Vbias in accordance with some embodiments of the present disclosure. InFIG.3, a curve C1represents one optical characteristic of the optical sensor30in the condition that the bias voltage Vbias has the first voltage level V1, and a curve C2represents another optical characteristic of the optical sensor30in the condition that the bias voltage Vbias has the second voltage level V2.

In the condition that the bias voltage Vbias has the first voltage level V1, the light having the wavelength shorter than 1000 nm penetrates into the photoelectric conversion layer31to a shallower depth, but the light having the wavelength exceeding 1000 nm penetrates into the photoelectric conversion layer31to a deeper depth. Therefore, the optical sensor30is easy to collect the photogenerated carriers (e.g., electrons, holes, etc.) of the light having the wavelength exceeding 1000 nm, but is much difficult to collect the photogenerated carriers of the light having the wavelength shorter than 1000 nm. As a result, as shown inFIG.3, the optical sensor30is controlled in an absorption spectrum range R1according to the bias voltage Vbias having the first voltage level V1. In the embodiments ofFIG.3, the absorption spectrum range R1may have a peak wavelength P1, the peak wavelength P1of the absorption spectrum range R1is substantially 1100 nm, but the present disclosure is not limited herein. For example, in some embodiments, the peak wavelength P1of the absorption spectrum range R1is substantially 940, 1310, 1350, 1400, 1450, or 1550 nm.

In the condition that the bias voltage Vbias has the second voltage level V2greater than the first voltage level V1in magnitude, the optical sensor30becomes easier to collect the photogenerated carriers of the light having the wavelength shorter than 1000 nm with the help of a strong electric field generated by the bias voltage Vbias having the second voltage level V2. As a result, as shown inFIG.3, the optical sensor30is controlled in an absorption spectrum range R2wider than the absorption spectrum range R1according to the bias voltage Vbias having the second voltage level V2. In the embodiments ofFIG.3, the absorption spectrum range R2is substantially between 400-1100 nm, however, the present disclosure is not limited herein. For example, in some embodiments, the absorption spectrum range R2is substantially between 400-940 nm, 400-1310 nm, 400-1350 nm, 400-1400 nm, 400-1450 nm or 400-1550 nm.

In accordance with the embodiments ofFIG.3, the image sensor100is operated in a narrowband mode of the operation modes when the optical sensor has the absorption spectrum range R1according to the first voltage level V1, and is operated in a broadband mode of the operation modes when the optical sensor30has the absorption spectrum range R2wider than the absorption spectrum range R1according to the second voltage level V2.

Referring toFIG.2again, in the narrowband mode, the photoelectric conversion layer31of the optical sensor30is configured to absorb a first light L1with a first wavelength range, and is configured to generates a first current signal Ib1corresponding to the first light L1to the pixel circuit41. The first wavelength range is substantially corresponding to (e.g., within or mostly overlapping) the absorption spectrum range R1as shown inFIG.3. In the broadband mode, the photoelectric conversion layer31of the optical sensor30is configured to absorb a second light L2with a second wavelength range, and is configured to generates a second current signal Ib2corresponding to the second light L2to the pixel circuit41. The second wavelength range is substantially corresponding to (e.g., within or mostly overlapping) the absorption spectrum range R2as shown inFIG.3.

As can be seen from above that, the first light L1is near-infrared (NIR) light, shortwave infrared (SWIR) light, or a combination thereof. Also, the second light L2is ultraviolet (UV) light, visible light, NIR light, SWIR light, or a combination thereof.

The operation of the pixel circuit41would be described herein with reference toFIG.2again. First, the reset switch SW is closed to reset the amplifier A. When the reset switch SW is closed, the integrating capacitor Cfb is discharged, so that the output terminal of the amplifier A is reset to the reference voltage Vref. Afterward, the reset switch SW is opened. When the reset switch SW is opened and the photoelectric conversion layer31of the optical sensor30absorbs the first light L1or the second light L2, the photoelectric conversion layer31generates the first current signal Ib1or the second current signal Ib2to the pixel circuit41. Accordingly, the integrating capacitor Cfb is charged, and electric charges corresponding to the first current signal Ib1or the second current signal Ib2are accumulated in the integrating capacitor Cfb. As a result, an output signal Vout corresponding to the accumulated electric charges is generated at the output terminal of the amplifier A. It can be seen from above that the pixel circuit41is configured to output the output signal Vout according to the first current signal Ib1or the second current signal Ib2generated by the optical sensor30.

The structure of the image sensor of the present disclosure is not limited to the image sensor100ofFIG.1, which would be described below with reference toFIGS.4and6. Referring toFIG.4,FIG.4is a sectional diagram of an image sensor400in accordance with some embodiments of the present disclosure. In some embodiments, besides the first transparent conductive layer10, the second conductive layer20, the optical sensor30, the semiconductor substrate40, the microlens layer50and the protection layer60as shown inFIG.1, the image sensor400further includes a polymer layer70. As shown inFIG.4, the polymer layer70is arranged below the first transparent conductive layer10, and is between the first carrier transporting layer33and the photoelectric conversion layer31.

In some embodiments, the additional polymer layer70is configured to filter out the visible light with the wavelength range between 400-650 nm, which results in the optical sensor30of the image sensor400having optical characteristics different from those of the optical sensor30of the image sensor100. Referring toFIG.5,FIG.5is a schematic diagram of the optical characteristics of the optical sensor30of the image sensor400in accordance with some embodiments of the present disclosure. InFIG.5, a curve C3represents one optical characteristic of the optical sensor30of the image sensor400in the condition that the bias voltage Vbias has the second voltage level V2. The elements inFIG.5denoted by the same reference characters as those inFIG.3will not be repeatedly described herein.

In the condition that the bias voltage Vbias having the second voltage level V2is applied to the image sensor400, the optical sensor30of the image sensor400is controlled in an absorption spectrum range R3. As shown inFIG.5, the absorption spectrum range R3is wider than the absorption spectrum range R1, but is narrower than the absorption spectrum range R2(as shown inFIG.3) because the visible light with the wavelength range between 400-650 nm is filtered out by the polymer layer70. In the embodiments ofFIG.5, the absorption spectrum range R3is substantially between 650-1100 nm, however, the present disclosure is not limited herein. For example, in some embodiments, the absorption spectrum range R3is substantially between 650-940 nm, 650-1310 nm, 650-1350 nm, 650-1400 nm, 650-1450 nm or 650-1550 nm.

In addition, the image sensor400is operated in a wideband mode of the operation modes when the optical sensor30has the absorption spectrum range R3according to the second voltage level V2. Referring toFIG.4again, in the wideband mode, the photoelectric conversion layer31of the optical sensor30is configured to absorb a third light L3with a third wavelength range, and is configured to generates a third current signal Ib3corresponding to the third light L3to the pixel circuit41. Then, the pixel circuit41generates the output voltage Vout according to the third current signal Ib3. The third wavelength range of the third light L3is substantially corresponding to (e.g., within or mostly overlapping) the absorption spectrum range R3as shown inFIG.5. As can be seen from above that, the third light L3is visible light (having the wavelength longer than 650 nm), NIR light, SWIR light, or a combination thereof.

Referring toFIG.6,FIG.6is a sectional diagram of an image sensor600in accordance with some embodiments of the present disclosure. In some embodiments, besides the first transparent conductive layer10, the second conductive layer20, the optical sensor30, the semiconductor substrate40, the microlens layer50and the protection layer60as shown inFIG.1, the image sensor600further includes a multilayer film filter layer80. As shown inFIG.6, the multilayer film filter layer80is arranged over the microlens layer50via a low refractive index material85.

In some embodiments, the multilayer film filter layer80is configured to filter out the visible light with the wavelength range between 400-800 nm, which results in the optical sensor30of the image sensor600having optical characteristics different from those of the optical sensor30of the image sensor100. Referring toFIG.7,FIG.7is a schematic diagram of the optical characteristics of the optical sensor30of the image sensor600in accordance with some embodiments of the present disclosure. InFIG.7, a curve C3′ represents one optical characteristic of the optical sensor30of the image sensor600in the condition that the bias voltage Vbias has the second voltage level V2. The elements inFIG.7denoted by the same reference characters as those inFIG.3will not be repeatedly described herein.

In the condition that the bias voltage Vbias having the second voltage level V2is applied to the image sensor600, the optical sensor30of the image sensor600is controlled in an absorption spectrum range R3′. As shown inFIG.7, the absorption spectrum range R3′ is wider than the absorption spectrum range R1, but is narrower than the absorption spectrum range R2(as shown inFIG.3) because the visible light with the wavelength range between 400-800 nm is filtered out by the multilayer film filter layer80. In the embodiments ofFIG.7, the absorption spectrum range R3′ is substantially between 800-1100 nm, however, the present disclosure is not limited herein. For example, in some embodiments, the absorption spectrum range R3′ is substantially between 800-940 nm, 800-1310 nm, 800-1350 nm, 800-1400 nm, 800-1450 nm or 800-1550 nm.

In addition, the image sensor600is operated in the wideband mode when the optical sensor30has the absorption spectrum range R3′ according to the second voltage level V2. Referring toFIG.6again, in the wideband mode, the photoelectric conversion layer31of the optical sensor30is configured to absorb another third light L3′ with another third wavelength range, and is configured to generates another third current signal Ib3′ corresponding to the third light L3′ to the pixel circuit41. Then, the pixel circuit41generates the output voltage Vout according to the third current signal Ib3′. The third wavelength range of the third light L3′ is substantially corresponding to (e.g., within or mostly overlapping) the absorption spectrum range R3′ as shown inFIG.7. As can be seen from above that, the third light L3′ is visible light (having the wavelength longer than 800 nm), NIR light, SWIR light, or a combination thereof.

Referring toFIG.8,FIG.8is a sectional diagram of an image sensor800in accordance with some embodiments of the present disclosure. The first transparent conductive layer10, the optical sensor30and the protection layer60of the image sensor800are similar to the components denoted by the same reference characters ofFIG.1, and therefore the detailed descriptions thereof are omitted herein. The image sensor800includes a plurality of second conductive layers20. The microlens layer50of the image sensor800comprises a plurality of microlens51. The semiconductor substrate40of the image sensor800comprises a plurality of pixel circuits41. The second conductive layers20are respectively connected to the pixel circuits41. Each of the microlen51, the pixel circuit41and the second conductive layer20has elements, operations and connection relationships similar to the components denoted by the same reference characters ofFIG.1, and therefore the detailed descriptions thereof are omitted herein. The image sensor800further includes a color filter array layer90. As shown inFIG.8, the color filter array layer90is arranged between the microlens layer50and the protection layer60.

In some embodiments, as shown inFIG.8, the color filter array layer90includes a first color filter91, a second color filter93, a third color filter95, and a broadband filter97. In particular, the first color filter91is configured to allow red light of the visible light to pass through, the second color filter93is configured to allow green light of the visible light to pass through, and the third color filter95is configured to allow blue light of the visible light to pass through. In addition, the broadband filter97is configured to allow any light (e.g., UV light, visible light, NIR light, SWIR light, etc.) to pass through.

Referring toFIG.9,FIG.9is a schematic diagram of a camera device1in accordance with some related arts and a camera device9in accordance with some embodiments of the present disclosure. The camera device1includes an infrared (IR) sensor3, a color sensor5and an IR emitter7. The camera device1can use the color sensor5to sense ambient light and/or photograph, and can use both the IR sensor3and the IR emitter7to perform face recognition on a user2. The camera device9includes the image sensor800(as shown inFIG.8) and the IR emitter7. In accordance with the embodiments ofFIG.8, by adjusting the voltage level of the bias voltage Vbias, the camera device9can operate the image sensor800in the broadband mode for sensing the ambient light and/or photographing, and can also operates the image sensor800in the narrowband mode for performing the face recognition on the user2. As can be seen from above that, the image sensor800of the present disclosure can be used as a substitute for the IR sensor3and the color sensor5, so that the camera device9has the advantages of low cost and small overall circuit area. In some embodiments, the camera device9may be implemented as a front camera of a smart phone to increase the screen to body ratio.

Referring toFIG.10,FIG.10is a flow diagram of a control method1000in accordance with some embodiments of the present disclosure. In some embodiments, the control method1000is configured to control any of the image sensors100,400,600and800of the present disclosure. As shown inFIG.10, the control method1000includes steps S1001-S1002, but the present disclosure is not limited herein. For the convenience of descriptions, steps S1001-S1002would be described with the image sensor100ofFIGS.1-2.

In step S1001, the image sensor100is determined to be operated in one of multiple operation modes. In some embodiments, the operation mode of the image sensor100may be determined by the processing circuit45of the electronic imaging device according to an operation command. For example, the operation command indicates that a predetermined operation (e.g., photographing, face recognition, motion detection, machine vision, etc.) would be performed. The processing circuit45can choose the operation mode corresponding to the predetermined operation from the operation modes of the image sensor100.

In step S1002, the bias voltage Vbias applied to the optical sensor30of the image sensor100is adjusted according to the operation mode determined in step S401. As set forth above, the operation modes of the image sensor100are corresponding to the different voltage levels of the bias voltage Vbias. In some embodiments, a lookup table having the relationship between the operation modes of the image sensor100and the voltage levels of the bias voltage Vbias is pre-stored in the electronic imaging device, and is accessible to the processing circuit45. In such arrangement, the processing circuit45can find the voltage level corresponding to the operation mode determined in step S401through the lookup table, and controls the multiplexer43by the control signal Vc to adjust the bias voltage Vbias to the voltage level being found, so that the image sensor100would be operated in the operation mode determined in step S401. In accordance with the embodiments ofFIG.2, the bias voltage Vbias is adjusted to the first voltage level V1when the image sensor100is determined to be operated in the narrowband mode, and is adjusted to the second voltage level V2when the image sensor100is determined to be operated in the broadband mode. The operation of the image sensor100in the narrowband mode and the broadband mode are similar to those of the above embodiments, therefore are not repeatedly described herein. The controls of other image sensors400,600and800are similar to those of the image sensor100, therefore are omitted herein.

The process of manufacturing a portion of the image sensor of the present disclosure would be described herein with reference toFIGS.11A-11K. ReferringFIGS.11A-11K,FIGS.11A-11Kare sectional diagrams illustrating the process of manufacturing the optical sensor30and the first transparent conductive layer10in accordance with some embodiments of the present disclosure. In some embodiments, as shown inFIG.11A, a semiconductor layer1124is provided. The semiconductor layer1124can be implemented by the second conductive layer20and the semiconductor substrate40illustrated inFIG.1. Therefore, the descriptions of the semiconductor layer1124are omitted herein.

In some embodiments, as shown inFIG.11B, a second carrier transporting material1135, a photoelectric conversion material1131and a first carrier transporting material1133are sequentially formed on the semiconductor layer1124. In particular, the second carrier transporting material1135, the photoelectric conversion material1131and the first carrier transporting material1133each is formed by blade coating, slot-die coating, spin coating or screen printing.

In some embodiments, as shown inFIG.11C, a photoresist material1113is formed on the first carrier transporting material1133by spin coating. Then, as shown inFIG.11D, the photoresist material1113is sequentially exposed and developed to form a photoresist layer13on the first carrier transporting material1133.

In accordance with the embodiments ofFIG.11D, dry etching is performed over the semiconductor layer1124. While the dry etching is performed, the photoresist layer13formed on the first carrier transporting material1133is used as the etch mask. Accordingly, as shown inFIG.11E, the second carrier transporting layer35, the photoelectric conversion layer31and the first carrier transporting layer33are formed below the photoresist layer13. Thereafter, as shown inFIG.11F, the photoresist layer13is stripped off the first carrier transporting layer33, so that the optical sensor30is formed on the semiconductor layer1124.

In some embodiments, as shown inFIG.11G, a transparent conductive material1110is formed over the semiconductor layer1124, so as to envelop the optical sensor30on the semiconductor layer1124. As shown inFIG.11H, a photoresist material1161is formed on the transparent conductive material1110by spin coating. Then, as shown inFIG.11I, the photoresist material1161is sequentially exposed and developed to form a photoresist layer61on the transparent conductive material1110.

In accordance with the embodiments ofFIG.11I, the dry etching is performed over the semiconductor layer1124again. While the dry etching is performed, the photoresist layer61formed on the transparent conductive material1110is used as the etch mask. Accordingly, as shown inFIG.11J, the first transparent conductive layer10is formed below the photoresist layer61. Thereafter, as shown inFIG.11K, the photoresist layer61is stripped off the first transparent conductive layer10.

As can be seen from the above embodiments of the present disclosure, by applying the photoelectric conversion layer31with the thickness T1ranging from 500 to 10000 nm, the image sensors100,400,600and800of the present disclosure can be switched among multiple operation modes by controlling the voltage level of the bias voltage Vbias, so as to adapt to different applications. Based on the above, the image sensors100,400,600and800of the present disclosure have advantages of low cost and low fabrication complexity.

Although the present disclosure has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein. It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present disclosure without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims.