Optical fingerprint sensing module and display device

Abstract

The application provides an optical fingerprint sensing module and a display device. The optical fingerprint sensing module comprises: a thin film transistor arranged on a surface of a substrate; a first planarization layer arranged on a side of the thin film transistor away from the substrate, the first planarization layer being provided with a via hole; a conductive layer arranged on a surface of the first planarization layer away from the thin film transistor and connected with the thin film transistor through the via hole; an optical sensor arranged on a surface of the conductive layer away from the first planarization layer; a first passivation layer covering a side surface of the optical sensor, the first passivation layer having a first opening structure and a hollow structure, a normal projection of the hollow structure on the substrate being deviated from a normal projection of the optical sensor on the substrate; and a second planarization layer arranged on a side of the first passivation layer away from the substrate. The technical scheme provided by the embodiment of the application avoids the problem that the passivation layer between the planarization layers in the optical fingerprint sensing module is prone to bulging or peeling.

Description

Technical Field

[0001] This invention relates to the field of display technology, and in particular to an optical fingerprint sensing module and a display device. Background Technology

[0002] With the continuous development of display technology, fingerprint recognition technology can be applied to display devices.

[0003] Optical fingerprint sensing modules are a widely used type of fingerprint sensing module. The principle of an optical fingerprint sensing module is that the reflected light intensity from the valleys and ridges of a fingerprint is different. The optical fingerprint sensing module then converts the light signals of different intensities into electrical signals, thereby performing fingerprint recognition.

[0004] In currently used optical fingerprint sensing modules, the passivation layer located between the planarization layers is prone to bulging or peeling. Summary of the Invention

[0005] The present invention provides an optical fingerprint sensing module and a display device to avoid the problem that the passivation layer located between the planarization layers is prone to bulging or peeling.

[0006] According to one aspect of the present invention, an optical fingerprint sensing module is provided, comprising:

[0007] Substrate;

[0008] Thin-film transistors are disposed on the surface of the substrate;

[0009] A first planarization layer is located on the side of the thin-film transistor away from the substrate, and the first planarization layer is provided with vias;

[0010] A conductive layer is located on the surface of the first planarization layer away from the thin-film transistor and is connected to the thin-film transistor through the via.

[0011] An optical sensor is located on the surface of the conductive layer away from the first planarization layer;

[0012] A first passivation layer covers the side of the optical sensor. The first passivation layer has a first opening structure and a hollow structure. The first opening structure is used to expose at least a portion of the top surface of the optical sensor away from the conductive layer. The orthographic projection of the hollow structure on the substrate is offset from the orthographic projection of the optical sensor on the substrate.

[0013] The second planarization layer is disposed on the side of the first passivation layer that is away from the substrate.

[0014] In this technical solution, the first passivation layer has a first opening structure and a hollow structure. The first opening structure exposes at least a portion of the top surface of the optical sensor away from the conductive layer. The orthographic projection of the hollow structure on the substrate deviates from the orthographic projection of the optical sensor on the substrate. Because of the presence of the hollow structure, compared to a structure where the first passivation layer completely covers the conductive layer and the first planarization layer, the technical solution of this embodiment reduces the area of ​​the first passivation layer covering the conductive layer and the first planarization layer. Therefore, during the high-temperature curing process of the second planarization layer, gas or water vapor flowing from the first planarization layer towards the first passivation layer can escape through the hollow structure, increasing the escape area of ​​gas or water vapor and thus avoiding the problems of bulging and peeling of the first passivation layer. The first planarization layer can cover the unevenness caused by the various film layers of the thin-film transistor, forming a flat surface under the optical sensor. This makes the stress, electric field, and received light of each film layer of the optical sensor more uniform, thereby avoiding the problem of increased dark current caused by uneven film structure, effectively reducing the dark current of the optical sensor, and improving the yield of the optical sensor. The first passivation layer, covering the sides of the optical sensor, can effectively reduce the dark current of the optical sensor. The second planarization layer can cover the differences in unevenness caused by the various films of the optical sensor, and is used to provide a smooth surface for the preparation of other films.

[0015] Optionally, the hollow structure includes a hollow area;

[0016] The first planarization layer includes a first partial planarization layer and a second partial planarization layer, the conductive layer covers the first partial planarization layer, and the cutout area exposes at least a portion of the second partial planarization layer so that at least a portion of the second partial planarization layer is in contact with the second planarization layer.

[0017] In this technical solution, the hollowed-out area exposes at least a portion of the second planarization layer, allowing at least a portion of the second planarization layer to contact the first planarization layer. This reduces the area of ​​the first passivation layer covering the first planarization layer. Therefore, during the high-temperature curing process of the second planarization layer, gas or moisture flowing from the first planarization layer towards the first passivation layer can escape through the hollowed-out area, increasing the escape area of ​​gas or moisture and thus avoiding the problems of bulging and peeling of the first passivation layer.

[0018] Optionally, the cutout area is continuously disposed along the outer periphery of the optical sensor; the second portion of the planarization layer and a portion of the conductive layer are exposed from the cutout area.

[0019] In this technical solution, the hollowed-out structure exposes the entire second planarization layer and the conductive layer not covered by the optical sensor in the hollowed-out area, so that the second planarization layer can contact the first planarization layer, further reducing the area of ​​the first passivation layer covering the first planarization layer. Therefore, during the high-temperature curing process of the second planarization layer, the gas or water vapor flowing from the first planarization layer toward the first passivation layer can escape from the hollowed-out area, increasing the escape area of ​​gas or water vapor, thereby avoiding the problem of bulging and peeling of the first passivation layer.

[0020] Optionally, the hollowed-out area is provided corresponding to the second part of the planarization layer.

[0021] This technical solution ensures that the entire second planarization layer is in contact with the first planarization layer, further reducing the area of ​​the first passivation layer covering the first planarization layer. Therefore, during the high-temperature curing process of the second planarization layer, gas or moisture flowing from the first planarization layer towards the first passivation layer can escape through the hollowed-out area, increasing the escape area and thus preventing bulging and peeling of the first passivation layer. Furthermore, the portion of the first passivation layer with solid material in the hollowed-out area partially covers the conductive layer, effectively protecting the conductive layer's circuitry, blocking moisture, and preventing water and oxygen corrosion that could affect its electrical performance.

[0022] Optionally, the conductive layer includes a first conductive layer and a second conductive layer, and the optical sensor covers the first conductive layer;

[0023] The hollow area includes several through holes, and a connecting part is provided between adjacent through holes. The connecting part covers at least part of the second part of the conductive layer.

[0024] In this technical solution, the connecting part covers part or all of the second conductive layer, which can effectively protect the circuit of the conductive layer, block water vapor, and prevent the circuit of the conductive layer from being corroded by water and oxygen, thus affecting the electrical performance.

[0025] Optionally, the second planarization layer is provided with a second opening structure for exposing at least a portion of the top surface of the optical sensor away from the conductive layer.

[0026] In this technical solution, the second planarization layer is provided with a second opening structure, that is, the second planarization layer does not cover the entire top surface of the optical sensor away from the conductive layer, which can improve the intensity of the light received by the optical sensor, thereby improving the sensitivity of the optical sensor.

[0027] Optionally, the curing temperature of the first planarization layer is greater than the curing temperature of the second planarization layer.

[0028] In this technical solution, during the high-temperature curing process of the second planarization layer and other films on it, the curing temperature of the first planarization layer is higher than that of the second planarization layer, which can prevent the generation of some gas in the first planarization layer, thereby avoiding the accumulation of gas under the first passivation layer. Even when preparing the films on the first planarization layer, water vapor is introduced into the first passivation layer and the optical sensor. This water vapor can escape from the through holes of the hollow structure of the first passivation layer, thereby effectively alleviating the problems of bulging and peeling of the first passivation layer.

[0029] Optionally, it further includes a transparent electrode layer that covers the top surface of the optical sensor exposed by the second opening structure away from the conductive layer.

[0030] In this technical solution, the transparent electrode layer is used to extract the electrical signal from the optical sensor. The high transparency of the transparent electrode layer can increase the intensity of the light received by the optical sensor, thereby improving the sensitivity of the optical sensor.

[0031] Optionally, it may also include a second passivation layer, which at least covers the transparent electrode layer.

[0032] In this technical solution, the second passivation layer can effectively protect the transparent electrode layer, block water vapor, and prevent the circuit of the transparent electrode layer from being corroded by water and oxygen, thus affecting its electrical performance.

[0033] According to another aspect of the present invention, a display device is provided, including the optical fingerprint sensing module described in any embodiment of the present invention.

[0034] In this technical solution, the display device includes any of the optical fingerprint sensing modules described in the embodiments of the present invention, and therefore has the beneficial effects of the aforementioned optical fingerprint sensing module, which will not be repeated here.

[0035] The technical solution provided in this embodiment has a first passivation layer with a first opening structure and a hollow structure. The first opening structure exposes at least a portion of the top surface of the optical sensor away from the conductive layer. The orthographic projection of the hollow structure on the substrate deviates from the orthographic projection of the optical sensor on the substrate. Due to the presence of the hollow structure, compared to a structure where the first passivation layer completely covers the conductive layer and the first planarization layer, the technical solution of this embodiment reduces the area of ​​the first passivation layer covering the conductive layer and the first planarization layer. Therefore, during the high-temperature curing process of the second planarization layer, gas or water vapor flowing from the first planarization layer towards the first passivation layer can escape through the hollow structure, increasing the escape area of ​​gas or water vapor and thus avoiding the problems of bulging and peeling of the first passivation layer. The first planarization layer can cover the unevenness caused by the various film layers of the thin-film transistor, forming a flat surface under the optical sensor. This makes the stress, electric field, and received light of each film layer of the optical sensor more uniform, thereby avoiding the problem of increased dark current caused by uneven film structure, effectively reducing the dark current of the optical sensor, and improving the yield of the optical sensor. The first passivation layer covering the sides of the optical sensor can also effectively reduce the dark current of the optical sensor. The second planarization layer can cover the unevenness caused by the various films of the optical sensor, providing a smooth surface for the preparation of other films. It should be noted that when the optical fingerprint sensing module is integrated into the display device, and other films requiring high-temperature curing are formed on top of the second planarization layer, compared with the structure where the first passivation layer completely covers the conductive layer and the first planarization layer, the technical solution of this embodiment reduces the area of ​​the first passivation layer covering the conductive layer and the first planarization layer. Therefore, during the high-temperature curing process of the second planarization layer, gas or water vapor flowing from the first planarization layer toward the first passivation layer can escape through the hollow structure, increasing the escape area of ​​gas or water vapor, thereby avoiding the problem of bulging and peeling of the first passivation layer in the display device.

[0036] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the structure of an optical fingerprint sensing module according to an embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram of another optical fingerprint sensing module provided according to an embodiment of the present invention;

[0040] Figures 3-7 This is a schematic diagram of the structure corresponding to each step of the preparation method of an optical fingerprint sensing module provided in an embodiment of the present invention. Detailed Implementation

[0041] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0042] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0043] As described in the background section above, the passivation layer located between the planarization layers in currently used optical fingerprint sensing modules is prone to bulging or peeling. Through careful research, the inventors discovered that the optical fingerprint sensing module comprises a stack of thin-film transistors, a first planarization layer, an optical sensor, a passivation layer, and a second planarization layer. The optical sensor is connected to the thin-film transistor through vias in the first planarization layer. Both the second and first planarization layers require high-temperature curing processes. However, during the high-temperature curing of the second planarization layer, the first planarization layer, being an organic material such as resin, generates gases. Furthermore, moisture is introduced during the fabrication of the film layer above the first planarization layer. These gases or moisture, during the high-temperature curing of the second planarization layer, can cause bulging and peeling of the passivation layer between the first and second planarization layers.

[0044] To address the aforementioned technical problems, the embodiments of the present invention provide the following technical solutions:

[0045] See Figure 1 , Figure 1 This is a schematic diagram of the structure of an optical fingerprint sensing module according to an embodiment of the present invention. The optical fingerprint sensing module includes: a substrate 1; a thin-film transistor T1 disposed on the surface of the substrate 1; a first planarization layer 2 located on the side of the thin-film transistor T1 away from the substrate 1, and the first planarization layer 2 is provided with a via 20; a conductive layer M3 located on the surface of the first planarization layer 2 away from the thin-film transistor T1 and connected to the thin-film transistor T1 through the via 20; an optical sensor 3 located on the surface of the conductive layer M3 away from the first planarization layer 2; a first passivation layer 4 covering the side of the optical sensor 3, the first passivation layer 4 having a first opening structure 40 and a hollow structure, the first opening structure 40 being used to expose at least a portion of the top surface of the optical sensor 3 away from the conductive layer M3, and the orthographic projection of the hollow structure on the substrate 1 being offset from the orthographic projection of the optical sensor 3 on the substrate 1; and a second planarization layer 5 disposed on the side of the first passivation layer 4 away from the substrate 1.

[0046] In this embodiment, the first passivation layer 4 is provided with a first opening structure 40, which exposes the photosensitive area 30 of the optical sensor 3.

[0047] The first passivation layer 4 has a first opening structure 40 and a hollow structure. The first opening structure 40 is used to expose at least a portion of the top surface of the optical sensor 3 away from the conductive layer M3. The meaning of the deviation between the orthographic projection of the hollow structure on the substrate 1 and the orthographic projection of the optical sensor 3 on the substrate 1 is as follows:

[0048] The orthographic projection of the hollow structure of the first passivation layer 4 onto the substrate 1 does not overlap with the orthographic projection of the optical sensor 3 onto the substrate 1. Figure 1 An exemplary diagram shows a cutout structure including a cutout area that fully exposes the conductive layer M3 not covered by the optical sensor 3 and the first planarization layer 2 not covered by the conductive layer M3, such that the first planarization layer 2 and the second planarization layer 5 not covered by the conductive layer M3 are in direct contact.

[0049] Optionally, the thin-film transistor T1 includes a gate 10, an active layer 11, a source or drain 12, and a drain or source 13. The optical fingerprint sensing module also includes a first insulating layer 14, a second insulating layer 15, and a third insulating layer 16. The first insulating layer 14 provides insulation between the gate 10 and the active layer 11. When the optical fingerprint sensing module requires a capacitor, the gate 10 serves as one electrode of the capacitor, and the second insulating layer 15 acts as an insulating layer for the capacitor. It should be noted that this capacitor can be used as a storage capacitor in the driving circuit when the optical fingerprint sensing module is integrated into a display device. The third insulating layer 16 acts as an etching barrier layer, preventing damage to the thin-film transistor T1 during the patterning process of the first planarization layer 2.

[0050] The conductive layer M3 includes a first connecting line 21 and a second connecting line 22. The first connecting line 21 is connected to the source or drain 12 through a via 20, and the second connecting line 22 is connected to the drain or source 13 through a via 20. The source or drain 12 is connected to the source or drain region of the active layer 11 through a via located in the first insulating layer 14, and the drain or source 13 is connected to the drain or source region of the active layer 11 through a via located in the first insulating layer 14. The optical sensor 3 is connected to the second connecting line 22 to enable the optical sensor 3 to be connected to the thin-film transistor T1 through the via 20.

[0051] The technical solution provided in this embodiment has a first passivation layer 4 with a first opening structure 40 and a hollow structure. The first opening structure 40 is used to expose at least part of the top surface of the optical sensor 3 away from the conductive layer M3. The orthographic projection of the hollow structure on the substrate 1 is deviated from the orthographic projection of the optical sensor 3 on the substrate 1. Because of the presence of the hollow structure, compared with the structure in which the first passivation layer 4 completely covers the conductive layer M3 and the first planarization layer 2, the technical solution of this embodiment reduces the area of ​​the first passivation layer 4 covering the conductive layer M3 and the first planarization layer 2. Therefore, during the high-temperature curing process of the second planarization layer 5, the gas or water vapor flowing from the first planarization layer 2 toward the first passivation layer 4 can escape from the hollow structure, increasing the escape area of ​​gas or water vapor, thereby avoiding the problem of bulging and peeling of the first passivation layer 4. The first planarization layer 2 covers the unevenness caused by the various film layers of the thin-film transistor T1, creating a flat surface beneath the optical sensor 3. This results in more uniform stress, electric field, and received light across the various film layers of the optical sensor 3, effectively preventing the increase in dark current caused by uneven film structure and improving the yield of the optical sensor 3. The first passivation layer 4, covering the sides of the optical sensor 3, also effectively reduces the dark current. The second planarization layer 5 covers the unevenness caused by the various film layers of the optical sensor 3, providing a flat surface for the fabrication of other film layers. It should be noted that when the optical fingerprint sensing module is integrated into the display device, and other film layers requiring high-temperature curing are formed on top of the second planarization layer 5, compared to the structure in which the first passivation layer 4 completely covers the conductive layer M3 and the first planarization layer 2, the technical solution of this embodiment reduces the area of ​​the first passivation layer 4 covering the conductive layer M3 and the first planarization layer 2. Therefore, during the high-temperature curing process of the second planarization layer 5, the gas or water vapor flowing from the first planarization layer 2 toward the first passivation layer 4 can escape from the hollow structure, increasing the escape area of ​​gas or water vapor, thereby avoiding the problem of bulging and peeling of the first passivation layer 4 in the display device.

[0052] Optionally, see Figure 1 and Figure 2 , Figure 2 This is a schematic diagram of another optical fingerprint sensing module provided according to an embodiment of the present invention. In this optical fingerprint sensing module, the hollow structure includes a hollow area; the first planarization layer 2 includes a first partial planarization layer and a second partial planarization layer, the conductive layer M3 covers the first partial planarization layer, and the hollow area exposes at least a portion of the second partial planarization layer so that at least a portion of the second partial planarization layer is in contact with the second planarization layer.

[0053] That is, the first planarization layer and the second planarization layer together constitute the first planarization layer 2. The portion of the first planarization layer 2 covered by the conductive layer M3 is called the first planarization layer, and the remaining portion of the first planarization layer 2 is called the second planarization layer.

[0054] Figure 1 In the middle, the hollow structure includes a hollow area, which exposes the entire second part of the planarization layer.

[0055] Figure 2 In the hollow area, there are several through holes, and a connecting part 4a is provided between adjacent through holes. When the first passivation layer 4 covers the conductive layer M3, the connecting part 4a covers part of the second planarization layer, so that the hollow area only exposes part of the second planarization layer.

[0056] Specifically, the cutout area exposes at least a portion of the second planarization layer, so that at least a portion of the second planarization layer is in contact with the second planarization layer 5, reducing the area of ​​the first passivation layer 4 covering the first planarization layer 2. Therefore, during the high-temperature curing process of the second planarization layer 5, gas or water vapor flowing from the first planarization layer 2 toward the first passivation layer 4 can escape from the cutout area, increasing the escape area of ​​gas or water vapor, thereby avoiding the problem of bulging and peeling of the first passivation layer 4.

[0057] Optionally, based on the above technical solutions, see [reference needed]. Figure 1 The cutout area is continuously arranged along the outer periphery of the optical sensor 3; the second part of the planarization layer and part of the conductive layer M3 are exposed from the cutout area.

[0058] Right now Figure 1 In the hollow structure, the hollow area exposes the entire second planarization layer and the conductive layer M3 not covered by the optical sensor 3, so that the second planarization layer is in contact with the second planarization layer 5, further reducing the area of ​​the first passivation layer 4 covering the first planarization layer 2. Therefore, during the high-temperature curing process of the second planarization layer 5, the gas or water vapor flowing from the first planarization layer 2 toward the first passivation layer 4 can escape from the hollow area, increasing the escape area of ​​gas or water vapor, thereby avoiding the problem of bulging and peeling of the first passivation layer 4.

[0059] Optionally, based on the above technical solution, the hollow area is set to correspond to the second planarization layer.

[0060] If Figure 2 The removal of the first passivation layer 4 covering the second planarization layer corresponds to a technical solution where the hollow area and the second planarization layer are aligned. This ensures that the entire second planarization layer is in contact with the second planarization layer 5, further reducing the area of ​​the first passivation layer 4 covering the first planarization layer 2. Therefore, during the high-temperature curing process of the second planarization layer 5, gas or moisture flowing from the first planarization layer 2 towards the first passivation layer 4 can escape through the hollow area, increasing the escape area and thus preventing bulging and peeling of the first passivation layer 4. The portion of the hollow area containing solid material in the first passivation layer 4 partially covers the conductive layer M3, effectively protecting the circuitry of the conductive layer M3, blocking moisture, and preventing water and oxygen erosion of the conductive layer M3's circuitry, which would affect its electrical performance.

[0061] Optionally, based on the above technical solution, the conductive layer M3 includes a first conductive layer and a second conductive layer, and the optical sensor 3 covers the first conductive layer; the hollow area includes a plurality of through holes, and a connecting part 4a is provided between adjacent through holes, and the connecting part 4a covers at least part of the second conductive layer.

[0062] The first conductive layer and the second conductive layer together constitute the conductive layer M3. The portion of the first conductive layer covered by the optical sensor 3 is called the first conductive layer, and the remaining conductive layer M3 is called the second conductive layer.

[0063] See Figure 2 The connecting portion 4a covers the entire second conductive layer. In other embodiments, the connecting portion 4a may only cover a portion of the second conductive layer.

[0064] Specifically, the connecting part 4a covers part or all of the second conductive layer, which can effectively protect the circuit of the conductive layer M3, block water vapor, and prevent the circuit of the conductive layer M3 from being corroded by water and oxygen, thus affecting its electrical performance.

[0065] Optionally, based on the above technical solutions, such as Figure 1 and Figure 2 As shown, the second planarization layer 5 is provided with a second opening structure 50, which is used to expose at least a portion of the top surface of the optical sensor 3 away from the conductive layer M3. For example... Figure 1 and Figure 2 In the middle, the orthographic projection of the second opening structure 50 onto the substrate 1 is within the orthographic projection of the first opening structure 40 onto the substrate 1.

[0066] Specifically, the second planarization layer 5 is provided with a second opening structure 50, that is, the second planarization layer 5 does not cover the entire top surface of the optical sensor 3 away from the conductive layer M3, which can improve the intensity of the light received by the optical sensor 3, thereby improving the sensitivity of the optical sensor 3.

[0067] Optionally, based on the above technical solution, the curing temperature of the first planarization layer 2 is greater than the curing temperature of the second planarization layer 5.

[0068] It is understandable that during the high-temperature curing process of the second planarization layer 5 and other films on it that require high-temperature curing, since the curing temperature of the first planarization layer 2 is higher than that of the second planarization layer 5, the first planarization layer 2 can avoid generating some gas, thereby avoiding the accumulation of gas under the first passivation layer 4. Even when preparing the film layer above the first planarization layer 2, water vapor will be introduced into the first passivation layer 4 and the optical sensor 3. This water vapor can escape from the hollow structure of the first passivation layer 4, thereby effectively alleviating the problem of bulging and peeling of the first passivation layer 4.

[0069] Optionally, based on the above technical solutions, such as Figure 2 As shown, the optical fingerprint sensing module also includes a transparent electrode layer 6, which covers the top surface of the optical sensor 3 exposed by the second opening structure 50 away from the conductive layer M3.

[0070] Specifically, the transparent electrode layer 6 is used to extract the electrical signal of the optical sensor 3, and the high transparency of the transparent electrode layer 6 can increase the intensity of the light received by the optical sensor 3, thereby improving the sensitivity of the optical sensor 3.

[0071] Optionally, based on the above technical solutions, such as Figure 2 As shown, the optical fingerprint sensing module also includes a second passivation layer 7, which at least covers the transparent electrode layer 6.

[0072] Specifically, the second passivation layer 7 can effectively protect the transparent electrode layer 6, block water vapor, and prevent the circuit of the transparent electrode layer 6 from being corroded by water and oxygen, thus affecting its electrical performance.

[0073] This invention also provides a method for fabricating an optical fingerprint sensing module. Figures 3-7 This is a schematic diagram of the structure corresponding to each step of the preparation method of an optical fingerprint sensing module provided in an embodiment of the present invention.

[0074] See Figure 3A substrate 1 is provided, and a gate 10, an active layer 11, a source or drain 12, a drain or source 13, a first insulating layer 14, a second insulating layer 15, and a third insulating layer 16 are formed on the surface of the substrate 1. The gate 10, the active layer 11, the source or drain 12, and the drain or source 13 constitute a thin-film transistor T1.

[0075] See Figure 4 A first planarization layer 2 is formed on the surface of the thin-film transistor T1 away from the substrate 1, and a via 20 is formed in the first planarization layer 2.

[0076] See Figure 5 A conductive layer M3 is formed on the surface of the first planarization layer 2 away from the thin film transistor T1. The conductive layer M3 includes at least a first connection line 21 and a second connection line 22. The first connection line 21 is connected to the source or drain of the thin film transistor T1 through a via 20, and the second connection line 22 is connected to the drain or source of the thin film transistor T1 through a via 20.

[0077] See Figure 6 An optical sensor 3 is formed on the surface of the first planarization layer 2 away from the thin-film transistor T1. The optical sensor 3 is connected to the thin-film transistor T1 through a via 20. A portion of the second connecting line 22 is located between the optical sensor 3 and the first planarization layer 2 to enable the connection between the optical sensor 3 and the thin-film transistor T1.

[0078] See Figure 7 A first passivation layer 4 is formed on the side of the optical sensor 3, and the first passivation layer 4 only covers the side of the optical sensor 3. The optical sensor 3 includes a photosensitive area 30, and the first passivation layer 4 is provided with a first opening structure 40. The orthogonal projection area of ​​the first opening structure 40 on the substrate is equal to the orthogonal projection area of ​​the photosensitive area 30 on the substrate 1.

[0079] See Figure 1 A second planarization layer 5 is formed, and the second planarization layer 5 is provided with a second opening structure 50, which is used to expose at least a portion of the top surface of the optical sensor 3 away from the conductive layer M3.

[0080] See Figure 2 A transparent electrode layer 6 is formed, which covers the top surface of the optical sensor 3 exposed by the second opening structure 50 away from the conductive layer M3. A second passivation layer 7 is then formed, which at least covers the transparent electrode layer 6.

[0081] This invention also provides a display device. This display device includes any of the optical fingerprint sensing modules described in the above technical solutions, and therefore possesses the beneficial effects of the aforementioned optical fingerprint sensing modules, which will not be elaborated further here.

[0082] It should be noted that, in Figure 1 and Figure 2 In the optical fingerprint sensing module shown, at least one light-emitting unit is disposed on the side of the second planarization layer 5 away from the first passivation layer 4. The light-emitting unit is connected to the thin-film transistor T1 through vias located in the second planarization layer 5 and the first planarization layer 2, thereby enabling fingerprint recognition technology to be applied to the display device. A storage capacitor connected to the thin-film transistor T1 can also be disposed between the substrate 1 and the first planarization layer 2 as a driving circuit for the light-emitting unit.

[0083] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. An optical fingerprint sensing module, characterized in that, include: Substrate; Thin-film transistors are disposed on the surface of the substrate; A first planarization layer is located on the side of the thin-film transistor away from the substrate, and the first planarization layer is provided with vias; A conductive layer is located on the surface of the first planarization layer away from the thin-film transistor and is connected to the thin-film transistor through the via. An optical sensor is located on the surface of the conductive layer away from the first planarization layer; A first passivation layer covers the side of the optical sensor. The first passivation layer has a first opening structure and a hollow structure. The first opening structure is used to expose at least a portion of the top surface of the optical sensor away from the conductive layer. The orthographic projection of the hollow structure on the substrate is offset from the orthographic projection of the optical sensor on the substrate. The second planarization layer is disposed on the side of the first passivation layer that is away from the substrate; The hollow structure includes a hollow area; The first planarization layer includes a first partial planarization layer and a second partial planarization layer, the conductive layer covers the first partial planarization layer, and the cutout area exposes at least a portion of the second partial planarization layer so that at least a portion of the second partial planarization layer is in contact with the second planarization layer.

2. The optical fingerprint sensing module according to claim 1, characterized in that, The cutout area is continuously arranged along the outer periphery of the optical sensor; the second part of the planarization layer and part of the conductive layer are exposed from the cutout area.

3. The optical fingerprint sensing module according to claim 1, characterized in that, The hollowed-out area corresponds to the second part of the planarization layer.

4. The optical fingerprint sensing module according to any one of claims 1-3, characterized in that, The conductive layer includes a first conductive layer and a second conductive layer, and the optical sensor covers the first conductive layer. The hollow area includes several through holes, and a connecting part is provided between adjacent through holes. The connecting part covers at least part of the second part of the conductive layer.

5. The optical fingerprint sensing module according to claim 1, characterized in that, The second planarization layer is provided with a second opening structure, which is used to expose at least a portion of the top surface of the optical sensor away from the conductive layer.

6. The optical fingerprint sensing module according to claim 1, characterized in that, The curing temperature of the first planarization layer is greater than that of the second planarization layer.

7. The optical fingerprint sensing module according to claim 5, characterized in that, It also includes a transparent electrode layer that covers the top surface of the optical sensor exposed by the second opening structure away from the conductive layer.

8. The optical fingerprint sensing module according to claim 7, characterized in that, It also includes a second passivation layer, which at least covers the transparent electrode layer.

9. A display device, characterized in that, Includes the optical fingerprint sensing module as described in any one of claims 1-8.

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