Manufacturing method of an optical fingerprint device

Abstract

The present invention provides a manufacturing method for an optical fingerprint device. By using mechanical cutting or laser cutting to remove the part of the cover layer corresponding to the pad area of the image sensor, the pad area is exposed, achieving the purpose of avoiding the pad area of the image sensor in the cover layer, so as not to affect the electrical connection performance of the pad area. Since mechanical cutting or laser cutting is used to remove the cover layer, compared with the etching process in the prior art, the process time is saved, the production efficiency is improved, the production capacity is increased, and the manufacturing cost is reduced.

Description

Technical Field

[0001] The present invention relates to a manufacturing method of an optical fingerprint device. Background Art

[0002] Current fingerprint recognition solutions include optical technology, silicon technology (capacitive / radio frequency), ultrasonic technology, etc. Among them, optical fingerprint recognition technology has been widely used in portable electronic devices.

[0003] Optical fingerprint recognition technology uses an optical imaging device based on the principle of total internal reflection of light (FTIR). Light shines on the outer surface of a light-transmitting layer (such as organic or inorganic glass) pressed with fingerprints, and the reflected light is obtained by an image sensor. The amount of reflected light depends on the depth of fingerprint ridges and valleys pressed on the glass surface, as well as the grease and moisture between the skin and the glass. When the light shines through the glass to the center of the valley, total internal reflection occurs at the interface between the glass and the air, and the light is reflected to the image sensor. The light incident on the ridge does not undergo total internal reflection, but is absorbed by the contact surface between the ridge and the glass or diffusely reflected to other places, thus forming a fingerprint image on the image sensor.

[0004] Since a relatively large-sized microlens is required to increase the energy of incident light and achieve higher image quality, in the prior art, it is often necessary to provide a relatively thick light-transmitting layer (more than 50 μm) above the pixel unit and a relatively thick light-blocking layer (such as 15 - 50 μm) between the pixel units to solve the problem that incident light enters adjacent pixel units of the image sensor, thereby causing signal crosstalk. In addition, an infrared cut-off filter film needs to be provided above the pixel unit to reduce the infrared light in the incident light from entering the image sensor, causing noise crosstalk and image distortion, and improving the optical performance of the optical fingerprint device. However, it should be noted that the light-transmitting layer, the light-blocking layer, and the infrared cut-off filter film all need to avoid the pad area of the image sensor so as not to affect the electrical connection performance of the pad area.

[0005] In the prior art, usually, after coating a light-transmitting material and a light-blocking material on the surface of an image sensor wafer, the light-transmitting material and the light-blocking material corresponding to the pad area are removed through an etching process, so as to achieve the purpose of avoiding the pad area of the image sensor for the light-transmitting layer and the light-blocking layer. However, when a relatively thick light-transmitting layer and light-blocking layer are required, it is often necessary to coat multiple layers of light-transmitting material and light-blocking material, and the coating efficiency is relatively low. When etching and removing the light-transmitting material and the light-blocking material corresponding to the pad area, the etching efficiency is also relatively low, the production capacity is very limited, and the manufacturing cost is relatively increased. Summary of the Invention

[0006] The object of the present invention is to provide a manufacturing method of an optical fingerprint device, which improves production efficiency, increases production capacity, and reduces manufacturing cost.

[0007] In view of the above considerations, the present invention provides a method for manufacturing an optical fingerprint device, comprising the following steps: providing a wafer formed with a plurality of image sensors; forming a covering layer on the wafer, with a gap between the covering layer and the pad area of the image sensors; forming a plurality of microlenses on the wafer; removing, by mechanical cutting or laser cutting, a portion of the covering layer corresponding to the pad area of the image sensors to expose the pad area; thereby forming the optical fingerprint device.

[0008] Preferably, the covering layer having a gap with the pad area of the image sensors is a light-transmitting layer, and the light-transmitting layer is formed on the wafer by an adhesive method.

[0009] Preferably, a plurality of light-transmitting layers are formed on the wafer. By photolithography, a portion of the light-transmitting layer closest to the wafer corresponding to the pad area of the image sensors is removed. By mechanical cutting or laser cutting, a portion of the light-transmitting layer farthest from the wafer corresponding to the pad area of the image sensors is removed. By photolithography, mechanical cutting or laser cutting, a portion of the other light-transmitting layers corresponding to the pad area of the image sensors is removed to expose the pad area.

[0010] Preferably, the light-transmitting layer closest to the wafer is formed on the wafer by coating or adhesion, and the other light-transmitting layers are formed on the wafer by an adhesive method.

[0011] Preferably, the light-transmitting layer closest to the wafer is an organic light-transmitting film, and the other light-transmitting layers are organic light-transmitting films or glass.

[0012] Preferably, the organic light-transmitting film is a dry film.

[0013] Preferably, the covering layer having a gap with the pad area of the image sensors is a light-blocking layer, and the light-blocking layer is formed on the wafer by an adhesive method or an oxide layer bonding method.

[0014] Preferably, before the light-blocking layer is combined with the wafer, a portion of the light-blocking layer corresponding to the pad area of the image sensors is etched to form a groove.

[0015] Preferably, the method for manufacturing the optical fingerprint device further comprises: forming an infrared cut-off filter film between the covering layer and the wafer.

[0016] Preferably, the infrared cut-off filter film is made to avoid the portion corresponding to the pad area of the image sensors by a lift-off process or a jig blocking method.

[0017] The manufacturing method of the optical fingerprint device of the present invention removes the part of the cover layer corresponding to the pad area of the image sensor by means of mechanical cutting or laser cutting to expose the pad area, achieving the purpose of avoiding the pad area of the image sensor by the cover layer so as not to affect the electrical connection performance of the pad area. Since the cover layer is removed by mechanical cutting or laser cutting, compared with the etching process of the prior art, the process time is saved, the production efficiency is improved, the production capacity is increased, and the manufacturing cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Other features, objects, and advantages of the present invention will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings.

[0019] Figures 1 - 5 FIG. is a process schematic diagram of a method for manufacturing an optical fingerprint device according to a preferred embodiment of the present invention;

[0020] Figures 6 - 13 FIG. is a process schematic diagram of a method for manufacturing an optical fingerprint device according to another preferred embodiment of the present invention;

[0021] Figures 14 - 18 FIG. is a process schematic diagram of a method for manufacturing an optical fingerprint device according to still another preferred embodiment of the present invention.

[0022] In the figures, throughout the different views, the same or similar reference numerals denote the same or similar devices (modules) or steps. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The present invention provides a manufacturing method of an optical fingerprint device. By removing the part of the cover layer corresponding to the pad area of the image sensor by means of mechanical cutting or laser cutting to expose the pad area, the purpose of avoiding the pad area of the image sensor by the cover layer is achieved so as not to affect the electrical connection performance of the pad area. Since the cover layer is removed by mechanical cutting or laser cutting, compared with the etching process of the prior art, the process time is saved, the production efficiency is improved, the production capacity is increased, and the manufacturing cost is reduced.

[0024] In the following detailed description of the preferred embodiments, reference will be made to the accompanying drawings which form a part of the present invention. The accompanying drawings illustrate specific embodiments that can implement the present invention by way of example. The example embodiments are not intended to exhaust all embodiments according to the present invention. It can be understood that other embodiments can be utilized without departing from the scope of the present invention, and structural or logical modifications can also be made. Therefore, the following detailed description is not restrictive, and the scope of the present invention is defined by the appended claims.

[0025] The present invention provides a manufacturing method for an optical fingerprint device, comprising the following steps: providing a wafer formed with a plurality of image sensors; forming a covering layer on the wafer, with a gap between the covering layer and the pad region of the image sensors; forming a plurality of microlenses on the wafer; removing, by mechanical cutting or laser cutting, a part of the covering layer corresponding to the pad region of the image sensors to expose the pad region; thereby forming the optical fingerprint device.

[0026] The present invention will be described in detail below in conjunction with specific embodiments.

[0027] Embodiment 1

[0028] Refer to Figure 1 , provide a wafer 100 formed with a plurality of image sensors, the image sensors including a pad region 102 and a photosensitive region 103, and the pad region 102 and the photosensitive region 103 are spaced apart by a dashed line in the figure.

[0029] Refer to Figure 2 , form an infrared cut-off filter film 101 on a part of the wafer 100 corresponding to the photosensitive region 103 of the image sensors. Preferably, the infrared cut-off filter film 101 is made to avoid the part corresponding to the pad region 102 of the image sensors by means of a stripping process or a jig blocking method.

[0030] Those skilled in the art can understand that the infrared cut-off filter film 101 being located on the surface of the wafer 100 is only a preferred embodiment of the present invention. According to process and application requirements, the infrared cut-off filter film 101 can also be disposed at other positions between the subsequently formed light-transmitting layer 105 and the wafer 100 or above the light-transmitting layer 105.

[0031] Refer to Figure 3 , form a covering layer 105 on the wafer 100, shown here as forming a light-transmitting layer 105 on the wafer 100. The light-transmitting layer 105 is preferably an organic light-transmitting film, such as a dry film, and can be formed on the wafer 300 by an adhesion method. Therefore, there is a gap between the light-transmitting layer 105 and the pad region 102 of the image sensors.

[0032] Refer to Figure 4 , form a plurality of microlenses 109 on the wafer 100. Preferably, a light-blocking layer 108, such as formed of a black glue material, is formed between the microlenses 109 to reduce signal interference caused by light crosstalk. Those skilled in the art can understand that the light-blocking layer 108 being located above the light-transmitting layer 105 is only a preferred embodiment of the present invention. According to process and application requirements, the light-blocking layer 108 can also be disposed at other positions between the light-transmitting layer 105 and the wafer 100.

[0033] Refer to Figure 5, thinning the wafer 100; removing the part of the light-transmitting layer 105 corresponding to the pad area 102 of the image sensor by mechanical cutting or laser cutting to expose the pad area 102, thereby forming an optical fingerprint device as shown in Figure 5 Since the light-transmitting layer 105 is removed by mechanical cutting or laser cutting, compared with the etching process of the prior art, the process time is saved, the production efficiency is improved, the production capacity is increased, and the manufacturing cost is reduced.

[0034] Embodiment 2

[0035] Refer to Figure 6 , providing a wafer 300 formed with a plurality of image sensors, the image sensor including a pad area 302 and a photosensitive area 303, and the pad area 302 and the photosensitive area 303 are spaced apart by a dotted line in the figure.

[0036] Refer to Figure 7 , forming an infrared cut-off filter film 301 on the part of the wafer 300 corresponding to the photosensitive area 303 of the image sensor. Preferably, the infrared cut-off filter film 301 is made to avoid the part corresponding to the pad area 302 of the image sensor by a stripping process or a jig blocking method.

[0037] Those skilled in the art can understand that the infrared cut-off filter film 301 being located on the surface of the wafer 300 is only a preferred embodiment of the present invention. According to process and application requirements, the infrared cut-off filter film 301 can also be disposed at other positions between the subsequently formed light-transmitting layer 305 and the wafer 300, or between multiple light-transmitting layers 305, 307, or above the light-transmitting layer 307.

[0038] Refer to Figure 8 , forming a first light-transmitting layer 305 on the wafer 300. The first light-transmitting layer 305 is preferably an organic light-transmitting film, such as a dry film, and can be formed on the wafer 300 by coating or bonding. Here, it is shown as being formed on the wafer 300 by a coating method.

[0039] Refer to Figure 9 , preferably, removing the part of the first light-transmitting layer, i.e., the first light-transmitting layer 305 closest to the wafer 300, corresponding to the pad area 302 of the image sensor by photolithography to ensure the removal accuracy and the protection of the surface of the image sensor.

[0040] Refer to Figure 10 , forming a light-blocking layer 306, such as formed of a black glue material, on the first light-transmitting layer 305 to reduce signal interference caused by light crosstalk.

[0041] Those skilled in the art can understand that the light-blocking layer 306 being located between the multiple light-transmitting layers 305 and 307 is only a preferred embodiment of the present invention. According to process and application requirements, the light-blocking layer 306 can also be disposed at other positions between the light-transmitting layer 305 and the wafer 300 or above the light-transmitting layer 307.

[0042] Refer to Figure 11 , a second light-transmitting layer 307 is formed on the light-blocking layer 306. For the case of multiple light-transmitting layers, the light-transmitting layer closest to the wafer is preferably an organic light-transmitting film, such as a dry film, which can be formed on the wafer by coating or bonding; other light-transmitting layers can be organic light-transmitting films or glass, which are formed on the wafer by bonding. Therefore, the second light-transmitting layer 307 is formed on the wafer 300 by bonding, and there is a gap between the second light-transmitting layer 307 and the pad region 302 of the image sensor.

[0043] Refer to Figure 12 , a plurality of microlenses 309 are formed on the second light-transmitting layer 307; preferably, a light-blocking layer 308 formed of, for example, a black glue material can also be formed between the microlenses 309 to further reduce signal interference caused by light crosstalk.

[0044] Refer to Figure 13 , the wafer 300 is thinned; the portion of the second light-transmitting layer 307 corresponding to the pad region 302 of the image sensor is removed by mechanical cutting or laser cutting to expose the pad region 302, thereby forming an optical fingerprint device as shown in Figure 13 . Since the second light-transmitting layer 307 is removed by mechanical cutting or laser cutting, compared with the etching process in the prior art, the process time is saved, the production efficiency is improved, the production capacity is increased, and the manufacturing cost is reduced.

[0045] For the case of multiple light-transmitting layers, it is preferred to use mechanical cutting or laser cutting to remove the light-transmitting layer farthest from the wafer to save process time and improve production efficiency. Other light-transmitting layers in the middle can be removed either by photolithography or by mechanical cutting or laser cutting, so as to achieve the purpose of avoiding the pad region of the image sensor.

[0046] Embodiment III

[0047] Refer to Figure 14 , a first wafer 500 formed with a plurality of image sensors is provided. The image sensors include pad regions 502 and photosensitive regions 503, and the pad regions 502 and the photosensitive regions 503 are spaced apart by dashed lines in the figure.

[0048] Refer to Figure 15, a second wafer 506 for forming a light-shielding layer is provided. Those skilled in the art can understand that forming the light-shielding layer using the second wafer is only a preferred embodiment of the present invention. According to process and application requirements, the light-shielding layer can also be formed of materials such as black glue.

[0049] Preferably, before the second wafer 506 is bonded to the first wafer 500, the portion of the second wafer 506 corresponding to the pad region 502 of the image sensor is etched to form a groove, and an infrared cut-off filter film 501 is formed on the surface of the second wafer 506. In other preferred embodiments not shown, the infrared cut-off filter film 501 can also be made to avoid the portion corresponding to the pad region 502 of the image sensor by using a lift-off process or a jig blocking method.

[0050] Those skilled in the art can understand that the infrared cut-off filter film 501 being located on the surface of the second wafer 506 is only a preferred embodiment of the present invention. According to process and application requirements, the infrared cut-off filter film 501 can also be disposed at other positions between the second wafer 506 and the first wafer 500, or above the second wafer 506.

[0051] See Figure 16 , preferably, the second wafer 506 is formed on the first wafer 500 by means of adhesion or oxide layer bonding, and the second wafer is etched to form a light-shielding layer 506, and there is a gap between the light-shielding layer 506 and the pad region 502 of the image sensor.

[0052] See Figure 17 , a light-transmitting layer 505 is formed on the light-shielding layer 506, and a plurality of microlenses 509 are formed on the light-transmitting layer 505; preferably, a light-shielding layer 508 formed of, for example, black glue material can also be formed between the microlenses 509 to further reduce signal interference caused by light crosstalk.

[0053] See Figure 18 , the wafer 500 is thinned; the portion of the light-shielding layer 505 corresponding to the pad region 502 of the image sensor is removed by mechanical cutting or laser cutting to expose the pad region 502, thereby forming an optical fingerprint device as Figure 18 shown. Since the light-shielding layer 505 is removed by mechanical cutting or laser cutting, compared with the etching process of the prior art, the process time is saved, the production efficiency is improved, the production capacity is increased, and the manufacturing cost is reduced.

[0054] In summary, in the manufacturing method of the optical fingerprint device of the present invention, by using mechanical cutting or laser cutting to remove the part of the cover layer corresponding to the pad area of the image sensor, so as to expose the pad area, the purpose of avoiding the pad area of the image sensor by the cover layer is achieved, so as not to affect the electrical connection performance of the pad area. Since mechanical cutting or laser cutting is used to remove the cover layer, compared with the etching process of the prior art, the process time is saved, the production efficiency is improved, the production capacity is increased, and the manufacturing cost is reduced.

[0055] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, in any case, the embodiments should be regarded as exemplary and non-limiting. In addition, obviously, the word "including" does not exclude other elements and steps, and the phrase "one" does not exclude a plurality. A plurality of elements stated in the apparatus claims can also be implemented by one element. The words first, second, etc. are used to denote names and do not denote any particular order.

Claims

1. A manufacturing method of an optical fingerprint device, characterized in that, The method includes the following steps: Providing a wafer formed with a plurality of image sensors; Forming a covering layer on the wafer, with a gap between the covering layer and the pad area of the image sensors; Forming a plurality of microlenses on the wafer; Removing, by mechanical cutting or laser cutting, a part of the covering layer corresponding to the pad area of the image sensors to expose the pad area; Thereby forming the optical fingerprint device; The step of forming a covering layer on the wafer, with a gap between the covering layer and the pad area of the image sensors, includes: Forming a plurality of light-transmitting layers on the wafer, and removing, by photolithography, a part of the light-transmitting layer closest to the wafer corresponding to the pad area of the image sensors, and using the other light-transmitting layers as the covering layer with a gap between the covering layer and the pad area of the image sensors; or providing a light-blocking layer, etching a part of the light-blocking layer corresponding to the pad area of the image sensors to form a groove, and bonding the light-blocking layer to the wafer as the covering layer with a gap between the covering layer and the pad area of the image sensors; Forming an infrared cut-off filter film between the covering layer and the wafer, and making the infrared cut-off filter film avoid the part corresponding to the pad area of the image sensors by a lift-off process or a jig blocking method.

2. The manufacturing method of the optical fingerprint device according to claim 1, characterized in that, Removing, by mechanical cutting or laser cutting, a part of the light-transmitting layer farthest from the wafer corresponding to the pad area of the image sensors, and removing, by photolithography, mechanical cutting or laser cutting, a part of the other light-transmitting layers corresponding to the pad area of the image sensors to expose the pad area.

3. The manufacturing method of the optical fingerprint device according to claim 2, wherein The light-transmitting layer closest to the wafer is formed on the wafer by coating or bonding, and the other light-transmitting layers are formed on the wafer by bonding.

4. The manufacturing method of the optical fingerprint device according to claim 2, characterized in that, The light-transmitting layer closest to the wafer is an organic light-transmitting film, and the other light-transmitting layers are an organic light-transmitting film or glass.

5. The manufacturing method of the optical fingerprint device according to claim 4, wherein The organic light-transmitting film is a dry film.

6. The manufacturing method of the optical fingerprint device according to claim 1, characterized in that, The light-blocking layer is formed on the wafer by bonding or oxide layer bonding.

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