TWI642175B - Image sensor and manufacturing method of fingerprint identification device - Google Patents

Abstract

The present disclosure provides an image sensor and a method of manufacturing the fingerprint identification device. The image sensor comprises: a substrate; a photodiode layer formed on the substrate and comprising a plurality of photodiodes for converting the received light into electrical signals, wherein the photodiodes are spaced apart by an array Arranging a metal layer formed on the substrate and disposed on the photodiode layer, wherein the metal layer comprises a plurality of first openings, and each of the first openings is located at a position corresponding to the photodiode Passing light through the first openings to the photodiode; a light absorbing layer disposed on the metal layer for absorbing light reflected by the metal layer.

Description

Image sensor and method for manufacturing fingerprint identification device

The present disclosure relates to an image sensor, and more particularly to an image sensor for an optical fingerprint recognition device and a method of manufacturing the fingerprint recognition device.

In recent years, security systems have often used biometrics to identify individuals. This type of security system has been widely used in portable electronic devices, such as smart phones, tablets, or notebook computers. Biometrics technology includes face, iris, sound, fingerprint, etc. Among them, fingerprint identification is the most common. It mainly uses capacitive sensors or optical sensors to obtain fingerprint images of users and perform them. Comparison.

One of the optical fingerprint identification devices is a total reflection type fingerprint recognition device, which mainly comprises an optical component and an image sensor, wherein the optical component uses light-reflecting materials such as high reflection coefficient materials or lenses, cymbals and optical fibers to perform light. The reflection is transmitted, and the image sensor is mainly used to capture images of the fingerprint. Since the fingerprint is composed of a plurality of irregular concave and convex lines, when the finger has not touched the optical component, the light incident from the dense medium (ie, the air having a low refractive index, such as air) exceeds the critical angle, and total reflection is generated. When the finger touches the light component, the light that strikes the position of the finger ridge is absorbed, that is, the total reflection is destroyed. When the light hits the concave position of the finger, it is concave If the pattern is not in contact with the light component, the light will still form a total reflection. Therefore, compared with the embossing without total reflection, the concave pattern can totally reflect the light, and a pattern of fingerprint lines which are staggered in light and dark is formed. According to the principle of total reflection, the light is transmitted to the image sensor to obtain a fingerprint image, and then the calculation unit of the fingerprint identification device is used to calculate and record the feature points of each fingerprint, so that fingerprint recognition can be performed.

Please refer to FIG. 1, which shows a schematic diagram of a conventional optical fingerprinting device 10. The optical fingerprint identification device 10 includes a glass cover plate (in the application of the fingerprint device of the Under glass or the under display, the fingerprint identification device is attached to the glass of the mobile phone or the glass of the screen, and the finger is pressed against the relative position of the glass to obtain a fingerprint image 11 , a light source 12 , a first mirror 13 , a second mirror 14 , and an image sensor 15 , wherein the glass cover 11 , the first mirror 13 and the second mirror 14 constitute an optical fingerprint identification device 10 light components. The light generated by the light source 12 is transmitted to the first mirror 13 and is reflected by the first mirror 13 and the second mirror 14 to be irradiated on the finger on the cover glass 11, so that the light of the finger concave is irradiated. The total reflection is generated and is incident on the image sensor 15 to obtain a fingerprint image.

However, in the conventional optical fingerprinting device 10, the light R11 partially irradiated to the image sensor 15 is reflected by the image sensor 15 and transmitted to the cover glass 11 and again due to the glass cover 11 The finger re-reflects or partially reflects back to the image sensor 15, thereby causing a ghost. Specifically, please refer to FIG. 2, which shows a schematic diagram of the image sensor 15 in the conventional optical fingerprinting device 10. The image sensor 15 includes a substrate 151 and a photodiode layer 152, a metal layer 153, and a protective layer 154 formed on the substrate. Generally, the light R1 reflected from the cover glass 11 and incident on the photodiode layer 152 of the image sensor 15 is absorbed to generate a corresponding electrical signal. However, when the light R1 partially reflected from the cover glass 11 is irradiated to the metal layer 153, part of the light R1 is reflected by the metal layer 153 to be the light R11, and is transmitted to the glass cover 11, so The light R11 will again reflect the light R11 due to the finger on the cover glass 11 and hit the image sensor 15, thereby causing a superimposed fingerprint image.

In addition, in the optical fingerprint recognition device 1, in addition to the light generated by the light source 12, there is a small amount of stray light R2 from the outside, which is generated when the stray light R2 is irradiated to the image sensor 6. The fingerprint image has an impact.

In view of the above, it is necessary to provide a method for manufacturing an image sensor and a fingerprint recognition device to solve the problems of the prior art.

In order to solve the above technical problem, an object of the present disclosure is to provide an image sensor and a fingerprint identification device manufacturing method for an optical fingerprint identification device, which absorb light reflected by an image sensor to avoid exposure to an image. The light from the sensor is reflected back to the glass cover, causing the light to be reflected by the finger on the glass cover to the image sensor again, thereby avoiding the problem of fingerprint image overlay.

In order to achieve the above object, the present disclosure provides an image sensor having a first light absorbing layer disposed on a metal layer (Top Metal) disposed on the outermost layer of the image sensor for absorption. The light reflected from the metal layer.

In a preferred embodiment of the present disclosure, the first light absorbing unit is offset from the metal layer by a first lateral distance in a longitudinal direction.

In a preferred embodiment of the present disclosure, the first lateral distance is obtained by the following formula: L1=tan(θ)*D1, where L1 is the first lateral distance, and θ is light incident on the image sensor. The angle of incidence, and D1 is the first longitudinal distance between the first light absorbing layer and the metal layer.

In a preferred embodiment of the present disclosure, the image sensor includes a second light absorbing layer disposed on the first light absorbing layer, and the second light absorbing layer includes a plurality of third openings, and The positions of the third openings correspond to the positions of the first openings of the metal layer and the second openings of the first light absorbing layer.

In a preferred embodiment of the present disclosure, the second light absorbing layer is offset from the first light absorbing layer by a second lateral distance in a longitudinal direction.

In a preferred embodiment of the present disclosure, the second lateral distance is obtained by the following formula: L2=tan(θ)*D2, where L2 is the second lateral distance, and θ is incident on the image sensor. The angle of incidence, and D2 is the second longitudinal distance between the first light absorbing layer and the second light absorbing layer.

In a preferred embodiment of the present disclosure, the first light absorbing layer includes a plurality of second openings, and the positions of the second openings correspond to the positions of the first openings of the metal layer.

In a preferred embodiment of the present disclosure, the opening area of the second opening located near the source of the light incident to the image sensor is the smallest, and the second opening is located away from the source of the light source. The opening area is the largest, and the opening area of the second openings gradually increases from a position near the source of the light incident to the image sensor to a position away from the source of the light.

The disclosure further provides a method for manufacturing a fingerprint identification device, comprising: providing an image sensor as described above; providing a light source disposed on one side of the image sensor for generating a light; and providing a glass cover a plate disposed on the image sensor and the light source, wherein the light is irradiated to a finger on the glass cover via a light transmission path, so that the light is irradiated The light of the concave pattern is totally reflected and is incident on the image sensor to obtain a fingerprint image.

In a preferred embodiment of the present disclosure, the first light absorbing layer of the image sensor is formed integrally with the image sensor when the image sensor is manufactured.

In a preferred embodiment of the present disclosure, when the image sensor is manufactured, a semi-finished product without the first light absorbing layer is formed first, and then the light transmission path determined according to the light source and according to the glass The thickness of the cover is used to form the first light absorbing layer on the semi-finished product by an additional process to complete the image sensor.

In a preferred embodiment of the present disclosure, when the image sensor includes the second light absorbing layer, the image sensor is first formed without the first light absorbing layer and the second a semi-finished product of the light absorbing layer, and then forming the first light absorbing layer and the second light absorbing layer on the semi-finished product according to the light transmission path determined by the light source and according to the thickness of the glass cover plate by an additional process To complete the image sensor.

In a preferred embodiment of the present disclosure, when the image sensor includes the second light absorbing layer and the third light absorbing layer, the image sensor is first formed without the first a semi-finished product of the light absorbing layer, the second light absorbing layer and the third light absorbing layer, and then on the semi-finished product by an additional process according to the light transmission path determined by the light source and according to the thickness of the glass cover The first light absorbing layer, the second light absorbing layer and the third light absorbing layer are formed to complete the image sensor.

Compared with the prior art, the present disclosure provides a light absorbing layer disposed above the metal layer in the image sensor, so that the light reflected through the metal layer can be absorbed by the light absorbing layer, thereby preventing the light from being reflected back to the glass cover and again A problem that is reflected onto the image sensor and produces a fingerprint image overlay. Secondly, the aperture ratio of the photosensitive pixels in different regions of the image sensor is adjusted by the light absorbing layer, The amount of light entering each area of the image sensor is adjusted to be uniform, so that the brightness of the obtained fingerprint image is uniform.

10, 20‧‧‧ Optical fingerprint identification device

11, 21‧‧‧ glass cover

12, 22‧‧‧ Light source

13, 23‧‧‧ first mirror

14, 24‧‧‧ second mirror

15, 25, 35, 45, 55, 65‧‧‧ Image Sensors

151, 251‧‧‧ substrate

2511‧‧‧ positive

2512‧‧‧Back

152, 252, 352, 452, 552, 652‧‧‧ Photodiode layers

153, 253, 353, 453, 553, 653‧‧ metal layers

154, 254, 354‧ ‧ protective layer

256, 356, 456A, 556A, 656‧‧‧ first light absorbing layer

456B, 556B‧‧‧second light absorbing layer

556C‧‧‧ third light absorbing layer

PD‧‧‧Photoelectric diode

R1, R11‧‧‧ rays

R2‧‧‧ stray light

D1‧‧‧First longitudinal distance

D2‧‧‧Second longitudinal distance

L1‧‧‧ first lateral distance

L2‧‧‧ second lateral distance

Θ‧‧‧incidence angle

X, Y‧‧‧ coordinates

P1‧‧‧ first opening

P2, P21, P22, P23‧‧‧ second opening

P3‧‧‧ third opening

A1, A2, A3‧‧‧opening area

A-A, B-B‧‧‧ cut line

S11~S13, S21~S25‧‧‧ steps

1 is a schematic view showing a conventional optical fingerprinting device; FIG. 2 is a schematic view showing an image sensor in a conventional optical fingerprinting device; and FIG. 3 is a view showing a first preferred embodiment according to the present disclosure. FIG. 4 is a schematic top view of the image sensor of the optical fingerprinting device of FIG. 3; FIG. 5 is a schematic cross-sectional view along the cutting line AA of FIG. 4; 6 is a schematic diagram showing an image sensor of an optical fingerprinting device according to a second preferred embodiment of the present disclosure; and FIG. 7 is a view showing image sensing of an optical fingerprinting device according to a third preferred embodiment of the present disclosure. FIG. 8 is a schematic view showing an image sensor of an optical fingerprinting device according to a fourth preferred embodiment of the present disclosure; and FIG. 9 is a view showing an optical fingerprinting device according to a fifth preferred embodiment of the present disclosure. FIG. 10 is a schematic cross-sectional view of the optical fingerprinting device of the present disclosure; FIG. 11 is a cross-sectional view of the optical fingerprinting device of the present disclosure; And Fig. 12 is a flow chart showing another manufacturing method of the optical fingerprinting device of the present disclosure.

The above and other objects, features, and advantages of the present invention will become more apparent and understood.

Please refer to FIG. 3, which shows a schematic diagram of an optical fingerprint recognition device 20 according to a first preferred embodiment of the present disclosure. The optical fingerprint recognition device 20 includes a glass cover 21, a light source 22, a first mirror 23, a second mirror 24, and an image sensor 25. The light source 22 is used to generate the light R1, wherein the light source may be an infrared light source, a white light source or the like, and is not limited thereto. The glass cover 21, the first mirror 23 and the second mirror 24 constitute an optical component of the optical fingerprinting device 20. The light emitted by the light source 12 is reflected by the light transmission path defined by the first mirror 23 and the second mirror 24, and then is irradiated onto the finger located on the glass cover 21, so that the light that is irradiated to the finger concave surface is totally reflected and is incident to The image sensor 25 converts the incident optical signal into an electrical signal via the image sensor 25 to obtain a fingerprint image. It can be understood that in other embodiments, the design without the first mirror 23 and the second mirror 24 can also be adopted, that is, the light source 22 is directly irradiated on the glass via a collimated light transmission path. Finger on the cover 21.

Please refer to FIG. 4 and FIG. 5 , wherein FIG. 4 shows a top view of the image sensor 25 of the optical fingerprinting device 20 of FIG. 3 , and FIG. 5 shows a cut line along the fourth figure. Schematic diagram of the AA. As shown in FIGS. 4 and 5, the image sensor 25 includes a substrate 251, a photodiode layer 252, a metal layer 253, a protective layer 254, and a first light absorbing layer 256. The substrate 251 includes a front surface 2511 and a back surface 2512 opposite the front surface 2511, wherein light reflected from the light source 22 via the light assembly is incident on the front surface 2511 of the substrate 251. The photodiode layer 252 is formed on the substrate 251 and includes a plurality of photodiodes PD, and the photodiodes PD are arranged in an array at intervals (as shown in FIG. 4). The metal layer 253 is formed on the substrate 251 and disposed on the photodiode layer 252, wherein the metal layer 253 includes a plurality of first openings P1, and each of the first openings P1 is in the pair The position of the photodiode PD is applied to allow light to pass through the first opening P1 to the photodiode layer 252. A protective layer 254 is disposed over the metal layer 253 for protecting the components on the front side 2511 of the substrate 251. The first light absorbing layer 256 is disposed on the protective layer 254 for absorbing light reflected by the metal layer 253. Moreover, the first light absorbing layer 256 includes a plurality of second openings P2, and the position of the second opening P2 corresponds to the position of the first opening P1 of the metal layer 253, so that the light can pass through the first opening P1 and the second opening P2 is delivered to the photodiode layer 252.

As shown in Fig. 5, in the longitudinal direction Y, the first light absorbing layer 256 is offset from the metal layer 253 by a first lateral distance L1, and the first lateral distance L1 is obtained by the following formula: L1 = tan(θ) *D1, where L1 is the first lateral distance, θ is the incident angle at which the light is incident on the image sensor 25, and D1 is the first longitudinal distance between the first light absorbing layer 256 and the metal layer 253. It should be understood that, in this embodiment, the first light absorbing layer 256 and the metal layer 253 are located on opposite sides of the protective layer 254, that is, the distance between the first light absorbing layer 256 and the metal layer 253 is equal to the protective layer 254. Thickness, however, in other embodiments, the first light absorbing layer 256 and the metal layer 253 may include elements other than the protective layer 254, and the distance between the first light absorbing layer 256 and the metal layer 253 is naturally not equal to the protective layer. 254 thickness. It should be noted that the first light absorbing layer 256 is offset toward the direction of the light source incident on the image sensor 25 (i.e., the location of the light source 22). With this design, when the light is irradiated onto the metal layer 253 and the light reflected by the metal layer 253 can be absorbed by the first light absorbing layer 256 above the metal layer 253 without being irradiated to the glass cover 21 again, it can be effectively The problem that the light is reflected back to the glass cover 21 and reflected again to the image sensor 25 to cause fingerprint image overlay is avoided.

Please refer to FIG. 6 , which shows a schematic diagram of an image sensor 35 of the optical fingerprint identification device according to the second preferred embodiment of the present disclosure. Optical fingerprinting of the second preferred embodiment The structure and features of the image sensor 35 of the device are substantially the same as those of the image sensor 25 of the first preferred embodiment, with the difference that the first light absorbing layer 356 of the image sensor 35 is not directly opposite the protective layer 354. Contact, that is, in the same longitudinal direction Y, between the first light absorbing layer 356 and the corresponding metal layer 353, other elements than the protective layer 354 (not shown) are provided. In addition, in the same manner, in the longitudinal direction Y, the first light absorbing layer 356 is offset from the metal layer 353 by a first lateral distance L1, and the first lateral distance L1 is obtained by the following formula: L1 = tan (θ *D1, where L1 is the first lateral distance, θ is the incident angle at which the light is incident on the image sensor 35, and D1 is the first longitudinal distance between the first light absorbing layer 356 and the metal layer 353.

As shown in Fig. 6, in addition to the incident light ray R1 along the normal light path, there are other various angles of incident light. These incident light is not the light reflected by the finger but the stray light R2 from the outside. The stray light R2 interferes with the resulting fingerprint image. Therefore, in the second preferred embodiment, by disposing the first light absorbing layer 356 at a large distance from the photodiode layer 352, the stray light R2 can be effectively shielded, thereby preventing the stray light R2 from being incident on the image. Inside the sensor 35.

Please refer to FIG. 7 , which shows a schematic diagram of an image sensor 45 of the optical fingerprint identification device according to the third preferred embodiment of the present disclosure. The structure and features of the image sensor 45 of the optical fingerprinting device of the third preferred embodiment are substantially the same as those of the image sensor 35 of the second preferred embodiment, with the difference that the image sense of the third preferred embodiment The detector 45 includes two light absorbing layers, a first light absorbing layer 456A and a second light absorbing layer 456B, and the first light absorbing layer 456A and the second light absorbing layer 456B are correspondingly disposed above the metal layer 453. Moreover, the metal layer 453 includes a plurality of first openings P1 corresponding to the photodiode layer 452, the first light absorbing layer 456A includes a plurality of second openings P2 corresponding to the first openings P1, and the second light absorbing layer 456B includes a plurality of And second opening The third opening P3 corresponding to P2, in this way, light can be transmitted to the photodiode layer 452 via the first opening P1, the second opening P2 and the third opening P3.

As shown in FIG. 7, in the longitudinal direction Y, the first light absorbing layer 456A is spaced apart from the metal layer 453 by a first longitudinal distance D1, and the first light absorbing layer 456A is spaced apart from the second light absorbing layer 456B by a second longitudinal direction. Distance D2. And, in the same longitudinal direction, the first light absorbing layer 456A and the second light absorbing layer 456B are offset from each other by a second lateral distance L2, wherein the second lateral distance is obtained by the following formula: L2=tan(θ)*D2 Where L2 is the second lateral distance, θ is the incident angle at which the light is incident on the image sensor, and D2 is the distance between the first light absorbing layer 456A and the second light absorbing layer 456B. As described above, when an optical fingerprinting device is used, there are other various angles of incident light in addition to the incident light ray R1 along the normal optical path. These incident light is not the light reflected by the finger but the stray light R2 from the outside. The stray light R2 interferes with the resulting fingerprint image. Therefore, in the third preferred embodiment, by providing a plurality of light absorbing layers and spacing the adjacent light absorbing layers and the photodiode layer 452 from each other, the stray light R2 can be effectively shielded, thereby avoiding stray light R2. It is incident into the photodiode layer 452.

Please refer to FIG. 8 , which shows a schematic diagram of an image sensor 55 of an optical fingerprint identification device according to a fourth preferred embodiment of the present disclosure. The structure and features of the image sensor 55 of the optical fingerprinting device of the fourth preferred embodiment are substantially the same as those of the image sensor 35 of the second preferred embodiment, with the difference that the image sense of the fourth preferred embodiment The detector 55 includes three light absorbing layers, namely a first light absorbing layer 556A, a second light absorbing layer 556B, and a third light absorbing layer 556C, and the first light absorbing layer 556A, the second light absorbing layer 556B, and the first The three light absorbing layer 556C is correspondingly disposed above the metal layer 553. By providing a plurality of light absorbing layers and arranging adjacent light absorbing layers and photodiode layers 552 apart from each other, stray light R2 can be effectively shielded, thereby avoiding miscellaneous The astigmatism R2 is incident into the photodiode layer 552.

Please refer to FIG. 9 and FIG. 10 . FIG. 9 is a top view of the image sensor 65 of the optical fingerprint identification device according to the fifth preferred embodiment of the present disclosure, and FIG. 10 shows the image along FIG. 9 . A schematic cross-sectional view of the cut line BB. The structure and features of the image sensor 65 of the optical fingerprinting device of the fifth preferred embodiment are substantially the same as those of the image sensor 25 of the first preferred embodiment, with the difference that the image sense of the fifth preferred embodiment The opening size of the plurality of second openings P2 of the first light absorbing layer 656 of the detector 65 may vary according to different positions. Specifically, as shown in FIG. 10, the second opening P21 located at a position close to the source of the light R1 incident on the image sensor 65 has the smallest opening area, and is located at the second opening P23 away from the source of the light R1. The opening area is the largest, and the opening area of the second opening P2 is gradually increased from a position near the source of the light R1 incident to the image sensor 65 to a position away from the source of the light R1, that is, the opening area of the second opening P23 is larger than The opening area of the second opening P22 and the opening area of the second opening P22 are larger than the opening area of the second opening P21.

Therefore, as shown in FIG. 9, the second opening P2 of different sizes is disposed in order to make the opening area of the photodiode PD of the corresponding photodiode layer 652 of the first light absorbing layer 656 close to the opening area. The position at which the light R1 originates is gradually reduced from the position away from the source of the light R1. Specifically, the aperture area A1 of the photodiode PD located near the source of the light R1 incident on the image sensor 65 is the smallest, and the aperture area A3 of the photodiode PD located away from the source of the light R1 is the smallest. The opening area of the photodiode PD is gradually increased from the position near the source of the light R1 incident on the image sensor 65 to the position away from the source of the light R1, that is, the opening area A3 is larger than the opening area A2, and is opened. The area A2 is larger than the opening area A1. Since the light energy close to the light source will be stronger, and the light energy away from the light source will be weak, so by close to the optical The aperture ratio of the photosensitive pixel of the light source of the fingerprint identification device is designed to be smaller than the photosensitive pixel away from the light source, so that the amount of light entering each area of the image sensor 65 is adjusted to be uniform, thereby obtaining uniform brightness of the obtained fingerprint image. It can be understood that the required aperture ratio of each region can be defined according to the simulated optical intensity map, and the opening size of the second opening P2 of the first light absorbing layer 656 of each region is adjusted according to the simulation result. Therefore, in the fifth preferred embodiment, the first light absorbing layer 656 can not only absorb the light reflected by the metal layer 653, but also appropriately change the aperture ratio of the photosensitive pixels of each region of the image sensor 65.

The disclosure also provides a method for manufacturing a fingerprint identification module. Please refer to FIG. 11 , which shows a flow chart of a manufacturing method of the optical fingerprint identification device of the present disclosure. First, step S11 is performed to provide any of the above image sensors. Next, step S12 is performed to provide a light source. The light source is disposed on one side of the image sensor for generating light. Finally, step S13 is performed to provide a cover glass. The glass cover is placed on the image sensor and the light source. Optionally, there is no other optical component between the light source and the cover glass, that is, the light source directly illuminates the finger on the cover glass via a collimated light transmission path; or the light source and the glass cover The first mirror and the second mirror as described above may be disposed between, that is, when the light is reflected by the light transmission path defined by the mirror, and then irradiated on the finger on the glass cover, so that the finger is concave The light will be totally reflected and will be incident on the image sensor to obtain a fingerprint image.

It should be noted that in the manufacturing method, the first light absorbing layer of the image sensor is formed simultaneously with the image sensor when manufacturing the image sensor, that is, the first light of the image sensor The absorbing layer is formed at the step S11.

Please refer to FIG. 12, which shows a flow chart of another manufacturing method of the optical fingerprint identification device of the present disclosure. First, step S21 is performed to provide half of any of the above image sensors. Finished product. Specifically, forming the semi-finished product of the image sensor means that the semi-finished product without the first light absorbing layer is formed first when the image sensor is manufactured. Next, step S22 is performed to determine the light source and the glass cover used by the optical fingerprint recognition device. Next, in step S23, a light absorbing layer is formed on the semi-finished product of the image sensor. That is, in step S21, the semi-finished product of the image sensor is first provided, and the first light absorbing layer of the image sensor is the light transmission path determined according to the light source and the thickness according to the glass cover plate at step S23. It is formed by an additional process. Next, step S24 is performed to provide the predetermined light source. It should be noted that the light source is disposed on one side of the image sensor for generating light. Finally, step S25 is performed to provide the above-mentioned predetermined glass cover. The glass cover is placed on the image sensor and the light source. Similarly, there may alternatively be no other optical elements between the light source and the cover glass, or a mirror as described above may be provided. By this design, when the light is irradiated on the finger on the glass cover through the light transmission path, the light that is irradiated to the finger concave will generate total reflection and be incident on the image sensor to obtain the fingerprint image.

In the manufacturing method, since the image sensor of the present disclosure is applied to a glass cover (for example, a mobile phone glass screen) to form a fingerprint image path, the light source according to the actual use, the defined light transmission path, and the glass are used. The thickness of the cover plate, and the parameters such as stray light and light uniformity compensation against different angles are determined, and then the size and position of the first and/or second and or third light absorbing layers are determined, and finally the light is processed by an additional process. An absorbing layer (for example, the first and/or second and third light absorbing layers) is formed on the semi-finished product of the image sensor to complete the manufacture of the image sensor, so that an optical fingerprint with an optimized design can be obtained. Device.

In summary, the present disclosure provides a light absorbing layer disposed above the metal layer in the image sensor, so that the light reflected through the metal layer can be absorbed by the light absorbing layer, thereby preventing the light from being reflected back to the glass cover and being reflected again. The problem of fingerprint image overlay on the image sensor. its Secondly, the aperture ratio of the photosensitive pixels in different regions of the image sensor is changed by the light absorbing layer to adjust the amount of light entering each area of the image sensor to be uniform, thereby obtaining uniform brightness of the obtained fingerprint image.

The present disclosure has been disclosed in the above preferred embodiments, and is not intended to limit the scope of the disclosure, and the present invention may be practiced without departing from the spirit and scope of the disclosure. Retouching, therefore, the scope of protection of this disclosure is subject to the definition of the scope of the patent application.

Claims (14)

An image sensor comprising: a substrate; a photodiode layer formed on the substrate and comprising a plurality of photodiodes for converting received light into electrical signals, wherein the photodiodes are Arrays are arranged at intervals; a metal layer is formed on the substrate and disposed on the photodiode layer, wherein the metal layer comprises a plurality of first openings, and each of the first openings is corresponding to the photodiode a position of the body to allow light to pass through the first opening to the photodiode layer; and a first light absorbing layer disposed on the metal layer for absorbing light reflected by the metal layer, wherein the The first light absorbing layer includes a plurality of second openings, and positions of the second openings correspond to positions of the first openings of the metal layer. The image sensor of claim 1, wherein the first light absorbing layer is offset from the metal layer by a first lateral distance in a longitudinal direction. The image sensor of claim 2, wherein the first lateral distance is obtained by the following formula: L1=tan(θ)*D1, wherein L1 is the first lateral distance, and θ is the light incident on the The angle of incidence of the image sensor, and D1 is the first longitudinal distance between the first light absorbing layer and the metal layer. The image sensor of claim 2, wherein the first light absorbing layer is relatively offset from the metal layer in a direction toward a source of light incident on the image sensor. The image sensor of claim 2, wherein the image sensor comprises a second light absorbing layer disposed on the first light absorbing layer, and the second light absorbing layer comprises a plurality of Three openings, and the positions of the third openings correspond to the positions of the first openings and the second openings. The image sensor of claim 5, wherein in the longitudinal direction, the The second light absorbing layer is offset from the first light absorbing layer by a second lateral distance. The image sensor of claim 6, wherein the second lateral distance is obtained by the following formula: L2=tan(θ)*D2, wherein L2 is the second lateral distance, and θ is that the light is incident on the The incident angle of the image sensor, and D2 is a second longitudinal distance between the first light absorbing layer and the second light absorbing layer. The image sensor of claim 1, wherein the image sensor further comprises a protective layer disposed between the metal layer and the first light absorbing layer. The image sensor of claim 1, wherein the second opening having a position close to a source of light incident on the image sensor has a smallest opening area, and is located away from the source of the light. The opening area of the second opening is the largest, and the opening area of the second openings gradually increases from a position near a source of light incident to the image sensor to a position away from the source of the light. A method for manufacturing a fingerprint identification device, comprising: providing an image sensor according to any one of claims 1 to 9; providing a light source disposed on one side of the image sensor for generating a light ray; and a glass cover plate disposed on the image sensor and the light source, wherein the light is irradiated to the finger on the glass cover via a light transmission path, so that the light illuminating the finger concave A total reflection is generated and is incident on the image sensor to obtain a fingerprint image. The method for manufacturing a fingerprint identification device according to claim 10, wherein the first light absorbing layer of the image sensor is formed integrally with the image sensor when the image sensor is manufactured. The method for manufacturing a fingerprint identification device according to claim 10, wherein when the image sensor is manufactured, a semi-finished product without the first light absorbing layer is formed first, and then the light is determined according to the light source. Transmission path and additional process according to the thickness of the glass cover The first light absorbing layer is formed on the semi-finished product to complete the image sensor. The method for manufacturing a fingerprint identification device according to claim 10, wherein when the image sensor includes the second light absorbing layer, the image sensor is first formed without the first light. a semi-finished product of the absorbing layer and the second light absorbing layer, and then forming the first light absorbing layer on the semi-finished product by an additional process according to the light transmission path determined by the light source and according to the thickness of the glass cover plate The second light absorbing layer completes the image sensor. The method for manufacturing a fingerprint identification device according to claim 10, wherein when the image sensor includes the second light absorbing layer and the third light absorbing layer, the image sensor is first Forming a semi-finished product without the first light absorbing layer, the second light absorbing layer and the third light absorbing layer, and then by the light transmission path determined by the light source and by the thickness according to the glass cover The process forms the first light absorbing layer, the second light absorbing layer and the third light absorbing layer on the semi-finished product to complete the image sensor.