CN212182328U

CN212182328U - Optical biometric sensor and electronic device

Info

Publication number: CN212182328U
Application number: CN202021320993.8U
Authority: CN
Inventors: 周正三; 范成至
Original assignee: Egis Technology Inc
Current assignee: Egis Technology Inc
Priority date: 2019-11-29
Filing date: 2020-07-08
Publication date: 2020-12-18
Anticipated expiration: 2030-07-08
Also published as: TWM602656U; KR20210001278U; KR200495669Y1

Abstract

The utility model discloses an optics biological characteristic sensor and electronic equipment. The optical biological characteristic sensor at least comprises an optical sensing chip, an optical-mechanical structure and a metal IR filter layer. The optical sensing chip at least comprises a substrate and one or more sensing pixels formed on the substrate. The optical-mechanical structure is positioned above the sensing pixels. The metal IR filter layer is arranged on one surface of the optical-mechanical structure. The sensing pixel senses an optical image of an object above the optical machine structure through the optical machine structure and the metal IR filtering layer, the metal IR filtering layer prevents infrared light of the environment where the object is located from entering the sensing pixel, and the thickness of the metal IR filtering layer is between 1 and 0.1 mu m. The utility model discloses can reduce the thickness of metal IR filter layer, solve traditional IR filter layer to the produced stress problem of optical sensing chip and the inhomogeneous problem of edge image, realize the thin screen down optical sensing's of change function.

Description

Optical biometric sensor and electronic device

Technical Field

The present invention relates to an optical biometric sensor and an electronic device, and more particularly, to an optical biometric sensor and an electronic device having a thinned metal IR filter layer.

Background

The present mobile electronic devices (such as mobile phones, tablet computers, notebook computers, etc.) are generally equipped with a user biometric identification system, which includes different technologies such as fingerprints, facial shapes, irises, etc. to protect personal data security, wherein, for example, the mobile electronic devices applied to mobile phones or smart watches, etc. also have a function of mobile payment, and become a standard function for user biometric identification, and the development of the mobile devices such as mobile phones is a trend toward full-screen (or ultra-narrow frame), so that the conventional capacitive fingerprint keys cannot be used any more, and further, new miniaturized optical imaging devices (very similar to the conventional camera module, having Complementary Metal-Oxide Semiconductor (CMOS) Image Sensor (CIS) sensing elements and optical lens modules) are evolved). The miniaturized optical imaging device is disposed below a screen (which may be referred to as under the screen), and an image of an object pressed On the screen, particularly a Fingerprint image, can be obtained through partial Light transmission of the screen (particularly an Organic Light Emitting Diode (OLED) screen), which may be referred to as under-screen Fingerprint sensing (FOD).

As shown in fig. 1, in a conventional under-screen optical fingerprint sensor module 300, in order to solve the problem of using outdoor sunlight, an optical engine structure 320 is generally disposed above a fingerprint sensor chip 310, and then an Infrared (IR) filter layer 330 is additionally attached to the optical engine structure 320, where the IR filter layer 330 is usually made of a glass substrate 332 with a thickness of 200 micrometers (μm) or more, and an IR filter film 334 with a multi-layer structure is formed on the glass substrate 332. However, disposing such an IR filter layer 330 under the display screen makes it impossible to effectively reduce the thickness of the mobile device.

To reduce the thickness of the mobile device, the limited space under the screen tends to limit the thickness of the IR filter layer. Therefore, as shown in fig. 2, the fingerprint sensor chip 310 can be directly used as a substrate, and the IR filter 334 with a multi-layer structure is directly formed on the surface of the fingerprint sensor chip 310 to block IR and reduce the thickness of the optical fingerprint sensor module 300. Current IR filters 334 use materials of different high and low refractive indices, such as silicon dioxide (SiO)₂) And titanium dioxide (TiO)₂) And the IR filter 334 fabricated in this way has a thickness of about 5 to 6 μm, which is reduced compared to fig. 1, but is still too thick to generate stress on the fingerprint sensor chip 310. In addition, the IR filter film 334 is coated with photoresist or deposited with a dielectric layer in a rotating manner, and the like, which is associated with etching, so that an uneven structure is easily formed at the edge of the IR filter film 334, resulting in uneven edge images and low production yield.

As shown in fig. 3 and fig. 2, the width of the distribution region S2 of the IR filter 334 with a thickness of 5 to 6 μm is the same as the width of the fingerprint sensing region S1 of the fingerprint sensor chip 310, which is likely to cause the edge of the optical engine structure 320 to be non-uniform, and thus cause the edge image to be non-uniform. For example, according to the research and observation of the present inventor, the background image sensed in the absence of a finger and the fingerprint image sensed in the presence of a finger have an uneven image in the inverted U-shaped peripheral areas on the upper, left, and right sides. These non-uniform conditions are a problem with the opto-mechanical structure 320 due to the IR filter 334. As for the lower region of the fingerprint image, there is no image non-uniformity because the lower region of the fingerprint sensing region S1 is covered by the distribution region S2 of the IR filter 334, i.e., the IR filter 334 extends down to region S3 and the fingerprint sensing region S1 does not extend to region S3.

As shown in fig. 4 and fig. 2, although the distribution region S2 of the IR filter 334 can be increased to have an area larger than the area of the fingerprint sensing region S1 to solve the problem of uneven edge image, such an increase in chip area and cost may cause problems.

SUMMERY OF THE UTILITY MODEL

Therefore, an object of the present invention is to provide an optical biometric sensor and an electronic device, which are used to solve the problem of non-uniformity of edge images, reduce the thickness of the optical biometric sensor, and eliminate the stress problem caused by the metal IR filter layer on the optical sensing chip.

To achieve the above objective, the present invention provides an optical biometric sensor, which at least includes an optical sensor chip, an opto-mechanical structure and a metal IR filter layer. The optical sensing chip at least comprises a substrate and one or more sensing pixels formed on the substrate. The optical-mechanical structure is positioned above the sensing pixels. The metal IR filter layer is arranged on one surface of the optical-mechanical structure. The sensing pixel senses an optical image of an object above the optical machine structure through the optical machine structure and the metal IR filtering layer, the metal IR filtering layer prevents infrared light of the environment where the object is located from entering the sensing pixel, and the thickness of the metal IR filtering layer is between 1 and 0.1 mu m.

The utility model also provides an electronic equipment includes at least: a housing; a display arranged on the shell; and the optical biological characteristic sensor is arranged between the display and the shell, wherein the object is positioned on or above the display, and the display displays information towards the direction of the object.

By utilizing the optical biological characteristic sensor and the electronic equipment, the thickness of the metal IR filter layer can be reduced, the problems of stress and uneven edge images of the traditional IR filter layer on an optical sensing chip are solved, and the thin-type optical sensing function under a screen is realized.

In order to make the above and other objects of the present invention more comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

Fig. 1 is a schematic diagram illustrating a conventional optical fingerprint sensor module.

Fig. 2 is a schematic diagram illustrating another conventional optical fingerprint sensor module.

Fig. 3 is a schematic partial top view illustrating a conventional optical fingerprint sensor module.

FIG. 4 is a schematic top view illustrating a variation of the optical fingerprint sensor module of FIG. 3

Fig. 5 is a schematic diagram showing an optical biometric sensor according to a preferred embodiment of the present invention.

Fig. 6 is a schematic diagram showing a variation of the optical biometric sensor according to the preferred embodiment of the present invention.

Fig. 7 is a schematic diagram illustrating an electronic device according to a preferred embodiment of the invention.

Fig. 8 is a schematic diagram showing another example of the electronic device according to the preferred embodiment of the present invention.

Reference numerals:

a1: first area

A2: second area

A3: third area

A4: fourth area

F: object

S1: fingerprint sensing area

S2: distribution area

S3: region(s)

T: thickness of

10: optical sensing chip

10T: upper surface of

11: substrate

12: sensing pixel

13: electric connection pad

20: optical-mechanical structure

20B: surface of

20T: upper surface of

30: metal IR filter layer

100: optical biometric sensor

200: electronic device

210: shell body

220: display device

221: light-transmitting substrate

222: light-transmitting substrate

300: optical fingerprint sensing module

310: fingerprint sensing chip

320: optical-mechanical structure

330: IR filter layer

332: glass substrate

334: IR filter

Detailed Description

An embodiment of the present invention provides an optical biometric sensor, which directly forms a metal IR filter layer on an optical sensor chip by Physical Vapor Deposition (PVD) (including but not limited to Sputtering or Evaporation) process, and then manufactures an opto-mechanical structure. The thickness of the metal IR filter layer can be made smaller than<1 μm, about SiO alone₂/TiO₂The manufactured IR filter layer has the advantage of being thinner, and can solve the problems of stress generated by the filter layer on a chip, uneven edge images and the like.

As shown in fig. 5, the optical biometric sensor 100 at least includes an optical sensor chip 10, an opto-mechanical structure 20 and a metal IR filter layer 30. In the present embodiment, the optical fingerprint sensor is taken as an example for explanation, but the present invention is not limited thereto, and the optical biometric sensor 100 may also sense biometric features such as blood vessel images and blood oxygen concentration images of fingers, or biometric features such as face shapes and irises.

The optical sensor chip 10 at least includes a substrate 11 and a plurality of sensor pixels 12, which are formed on the substrate 11 and arranged in a two-dimensional array. It is noted that although a plurality of sensor pixels 12 are illustrated as an example, the present disclosure is also applicable to the case of a single sensor pixel, without the presence of a two-dimensional array.

In the embodiment, the substrate 11 is a semiconductor substrate, and the optical sensor chip 10 is a CIS sensor chip, and is manufactured by a semiconductor process, which is compatible with the semiconductor process, so that mass production is possible and the cost is reduced.

Opto-mechanical structures 20 are located above the sensing pixels 12. In one example, the optical bench structure 20 may include an aperture, a light-shielding layer, and a microlens, and may also be formed by a semiconductor process. In another example, the optical engine structure 20 includes a collimator.

The metal IR filter layer 30 is disposed on a surface 20B of the optical machine structure 20. Alternatively, the metal IR filter layer 30 is formed on an upper surface 10T of the optical sensor chip 10 by a sputtering process of PVD, so that the metal IR filter layer 30 and the optical sensor chip 10 can be bonded. Bonding includes, but is not limited to, bonding of metal atoms to surfaces of oxides (e.g., silicon oxide or silicon dioxide), for example, and is different from conventional adhesive bonding. This is also compatible with semiconductor processing, so that the entire optical biometric sensor 100 can be fabricated using commercially available semiconductor fabrication equipment and processes, which has the advantages of mass production and cost reduction. In one example, after forming the sensing pixels 12 on the substrate 11, the metal IR filter layer 30 is formed by PVD, evaporation or sputtering after forming interconnects, inter-metal dielectric layers, inter-layer dielectric layers, and protective layers (such as silicon oxide or silicon dioxide) on the sensing pixels 12.

In actual operation, the sensing pixels 12 sense an optical image of an object F located above the optical-mechanical structure 20 through the optical-mechanical structure 20 and the metal IR filtering layer 30, and the metal IR filtering layer 30 blocks infrared light of the environment where the object F is located from entering the sensing pixels 12, so as to avoid sensing interference of biological characteristics under sunlight or infrared light sources. Here, the thickness T of the metal IR filter layer 30 is between 1 μm and 0.1 μm.

With the optical biometric sensor 100 described above, the stress problem caused by the metal IR filter layer 30 to the optical sensing chip is eliminated because the thickness of the metal IR filter layer 30 is greatly reduced. In addition, by spin-coating a photoresist or depositing a dielectric layer on the metal IR filter layer 30 in combination with etching, an uneven structure is not formed at the edge of the metal IR filter layer 30, so that the problem of uneven edge image can be solved. Furthermore, the thickness of the optical biometric sensor can be reduced.

In addition, in the embodiment, a first area a1 of the two-dimensional array is equal to a second area a2 of the metal IR filter layer 30, and the first area a1 is equal to a third area A3 of the optical bench structure 20 and is smaller than a fourth area a4 of the substrate 11. In this case, since the metal IR filter layer 30 is spin-coated with photoresist or deposited with a dielectric layer in combination with etching, the jitter of the sensing signal caused by the non-uniform structure at the edge of the metal IR filter layer 30 is avoided, and the second area a2 of the metal IR filter layer 30 does not need to be enlarged. Reference to area in the present disclosure refers to area corresponding to the horizontal plane of the drawing. It is noted that the first area a1 represents the distribution area of the sensing pixels 12, and the pitch (pitch) of the sensing pixels 12 can be calculated, for example, the first area a1 can extend to the outermost sensing pixels 12 plus one or half of the pitch. With this configuration, the metal IR filter layer 30 can still filter the oblique infrared light entering the peripheral sensing pixels 12.

In other examples, the thickness of the metal IR filter layer 30 is between 0.9 μm and 0.2 μm; between 0.8 and 0.3 μm; between 0.7 and 0.4 μm; between 0.7 and 0.5 μm; between 0.65 and 0.55 μm; or between 0.6 and 0.5 μm. In one example, the thickness of metallic IR filter layer 30 is equal to 0.6 μm. The metal IR filter layer 30 is disposed between the optical sensor chip 10 and the opto-mechanical structure 20, and particularly between the sensing pixels 12 and the opto-mechanical structure 20. In addition, the optical sensor chip 10 further includes a plurality of electrical connection pads 13 located outside the two-dimensional array, and the metal IR filter layer 30 does not cover the electrical connection pads 13. The metal IR filter layer 30 is mainly a metal film layer, such as Ag film, which can greatly reduce the thickness of the IR filter layer by utilizing the characteristic of Ag that absorbs light. The metal IR filter layer 30 may have a single-layer structure or a multi-layer structure, and its material includes a single layer or a combination of multiple layers of Ti, Ta, Al, Cu, etc., in addition to Ag.

Thus, fabricating the optical biometric sensor 100 of fig. 5 includes the following steps. First, the sensor pixel 12 and the interconnection, inter-metal dielectric layer, inter-layer dielectric layer and passivation layer thereon are formed on the substrate 11. Then, a PVD process is performed on the optical sensor chip 10 to form a metal IR filter layer 30, and then the optical-mechanical structure 20 is formed on the metal IR filter layer 30. It is noted that the substrate 11 may be a semiconductor substrate or a glass substrate or other insulating substrate, and the optical biometric sensor 100 in this case may be a photosensor fabricated by a Thin-Film Transistor (TFT) process; or a Complementary metal-oxide semiconductor (CMOS) process. The optical biometric sensor 100 is, for example, an in-cell optical sensor integrated in a TFT Liquid Crystal Display (LCD) or a TFT Organic Light Emitting Diode (OLED).

Sputtering is one type of PVD and refers to the physical process whereby atoms in a solid target are struck by high energy ions (usually from a plasma) and leave the solid into a gas. Sputtering can be carried out in a vacuum system filled with inert gas, argon is ionized through the action of a high-voltage electric field, an argon ion flow is generated, a target cathode is bombarded, and sputtered target material atoms or molecular precipitates are accumulated on a semiconductor chip or glass or ceramic to form a thin film. Sputtering has the advantages of being able to produce thin films of high melting point materials at lower temperatures, being able to bond to substrates without peeling, and not causing stress to the substrates, maintaining the original composition during the process of producing alloy and compound thin films, and thus having been widely used in the manufacture of semiconductor devices and integrated circuits.

In another example, the metal IR filter layer 30 may be formed by a PVD evaporation process, such as E-gun evaporation, in which the material to be evaporated is placed in a high vacuum chamber and heated by heating wires or electron beams to a melting and vaporizing temperature to evaporate the material to a coating technique that adheres to the substrate surface. During evaporation, the surface temperature of the plated object has a significant influence on the properties of the thin film formed by evaporation. The substrate needs to be heated properly so that the evaporated atoms can move freely on the surface of the substrate, and thus a uniform thin film can be formed. When the substrate is heated to above 150 ℃, the deposited film and the substrate can form a good bond without peeling.

As shown in fig. 6, this example is similar to fig. 5, except that the optical-mechanical structure 20 is disposed on the optical sensor chip 10, and the metal IR filter layer 30 is far away from the sensor pixels 12. That is, the metal IR filter layer 30 is disposed on an upper surface 20T of the optical bench structure 20, in which case, the metal IR filter layer 30 and the optical bench structure 20 can be bonded. In addition, the optical sensing chip 10 further includes a plurality of electrical connection pads 13 located outside the two-dimensional array, and the optical-mechanical structure 20 does not cover the electrical connection pads 13.

Thus, fabricating the optical biometric sensor 100 of fig. 6 includes the following steps. First, the sensor pixel 12 and the interconnection, inter-metal dielectric layer, inter-layer dielectric layer and passivation layer thereon are formed on the substrate 11. Then, an opto-mechanical structure 20 is formed on the optical sensor chip 10. Next, a PVD process is performed on the optical bench structure 20 to form a metal IR filter layer 30.

As shown in fig. 7, the present invention also provides an electronic apparatus 200, such as a mobile device like a mobile phone, which at least includes a housing 210, a display 220 and the optical biometric sensor 100. The display 220 and the optical biometric sensor 100 may be powered by a battery 230 of the electronic device 200. The display 220 is disposed on the housing 210. The optical biometric sensor 100 is disposed between the display 220 and the housing 210. The object F is positioned on or above the display 220, and the display 220 displays information in the direction of the object F to interact with the user. The display 220 is, for example, an OLED display, a micro-led display, etc., and can have a touch function at the same time.

As shown in fig. 8, this embodiment is similar to fig. 7, except that the substrate 11 of the optical biometric sensor 100 is a glass substrate, and the glass substrate is one of two opposite

transparent substrates

221, 222 of the display 220 (in fig. 8, the lower transparent substrate 221 is referred to, and the glass substrate is a part of the transparent substrate 221, so that the optical biometric sensor 100 is embedded in the display 220. therefore, the optical biometric sensor 100 of fig. 8 is a TFT sensor, which is an embedded sensor of LCD or OLED.

The embodiments presented in the detailed description of the preferred embodiments are only for convenience of description of the technical content of the present invention, and the present invention is not narrowly limited to the above embodiments, and various modifications can be made without departing from the spirit and scope of the present invention.

Claims

1. An optical biometric sensor, characterized in that it comprises at least:

an optical sensor chip, comprising:

a substrate; and

one or more sensing pixels formed on the substrate;

an opto-mechanical structure located above the one or more sensing pixels; and

the metal infrared light filtering layer is arranged on one surface of the optical machine structure, wherein the one or more sensing pixels sense an optical image of an object positioned above the optical machine structure through the optical machine structure and the metal infrared light filtering layer, the metal infrared light filtering layer prevents infrared light of the environment where the object is positioned from entering the one or more sensing pixels, and the thickness of the metal infrared light filtering layer is between 1 mu m and 0.1 mu m.

2. The optical biometric sensor according to claim 1, wherein the plurality of sensing pixels are arranged in a two-dimensional array having a first area equal to a second area of the metal infrared light filter layer.

3. The optical biometric sensor according to claim 2, wherein the first area is equal to a third area of the optical mechanical structure and less than a fourth area of the substrate.

4. The optical biometric sensor according to claim 1, wherein the metal infrared light filter layer has a thickness of 0.7 to 0.5 μm.

5. The optical biometric sensor according to claim 1, wherein the metal infrared light filter layer has a thickness of 0.65 to 0.55 μm.

6. The optical biometric sensor according to claim 1, wherein the metal infrared filter layer is disposed between the one or more sensing pixels and the opto-mechanical structure.

7. The optical biometric sensor according to claim 6, wherein the plurality of sensing pixels are arranged in a two-dimensional array, the optical sensing chip further comprises a plurality of electrical connection pads located outside the two-dimensional array, and the metallic infrared light filter layer does not cover the plurality of electrical connection pads.

8. The optical biometric sensor according to claim 6, wherein the metal infrared filter layer is bonded to the optical sensor chip.

9. The optical biometric sensor according to claim 1, wherein the opto-mechanical structure is disposed on the optical sensing chip and the metallic infrared light filter layer is remote from the one or more sensing pixels.

10. The optical biometric sensor according to claim 9, wherein the plurality of sensing pixels are arranged in a two-dimensional array, the optical sensing chip further comprising a plurality of electrical connection pads located outside the two-dimensional array, the opto-mechanical structure not covering the plurality of electrical connection pads.

11. The optical biometric sensor according to claim 9, wherein the metal infrared filter layer is bonded to the opto-mechanical structure.

12. An electronic device, characterized in that it comprises at least:

a housing;

a display arranged on the shell; and

the optical biometric sensor according to any one of claims 1 to 11, disposed between the display and the housing, wherein the object is located on or above the display, and the display displays information in the direction of the object.

13. The electronic device of claim 12, wherein the substrate of the optical biometric sensor is a glass substrate and the glass substrate is one of two opposing transparent substrates of the display, such that the optical biometric sensor is embedded in the display.