TWI738322B - Electronic device - Google Patents

Abstract

An electronic device including a plurality of micro-lenses, a light-limiting structure, a first light-transmitting structure and a sensing element is provided. The plurality of micro-lenses are arranged in an array. The sensing element includes a plurality of sensing pixels. The sensing element, the first light-transmitting structure, the light-limiting structure and the plurality of micro-lenses are sequentially stacked in a stacking direction. Each sensing pixel corresponds to at least two of the micro-lenses in the stacking direction.

Description

Electronic device

The present invention relates to a device, and more particularly to an electronic device.

At present, electronic devices are used in fingerprint recognition of smart phones, and capacitive fingerprint recognition systems are the mainstream. When the active and passive capacitive fingerprint recognition system is attached to a smart phone, it can be used for unlocking and function activation. For the current market situation, the installation of the fingerprint identification system is mainly based on the back of the smartphone. If it is installed in the front view area, it is necessary to open holes or perform thinning procedures for the glass display area, which causes an increase in processing costs. In addition, fingerprint recognition systems on the market also include ultrasonic fingerprint systems and optical fingerprint recognition systems. Because optical fingerprint recognition has high light penetration, it can recognize fingerprints and other features without opening holes in the glass display area. Therefore, the optical fingerprint recognition system has become the mainstream of next-generation fingerprint recognition.

There are currently several imaging systems for optical fingerprint recognition, such as reflection, film reflection, pinhole imaging, optical fiber imaging, or with multiple sets of lenses to become a larger fingerprint recognition imaging system.

However, due to the market trend of thinning, installing under the panel glass without opening holes and applying to mobile devices, the design of the optical fingerprint recognition system is difficult. For example, the thickness distribution of the glass panel of the display device falls within the range of 500 μm to 1 mm. In addition to the thickness of the light-emitting element and the air layer of the display device, the designer must make the thickness of the fingerprint recognition system less than 400 μm. Considering that the thickness of the sensing element is about 200 μm and the thickness of the substrate (such as a printed circuit board) of the fingerprint identification system is about 150 μm, the overall thickness of the remaining components is limited to a range of 50 μm.

Furthermore, because the resolution of fingerprint recognition must be at least 500dpi (dots per inch, dots per inch), the size of each pixel of the fingerprint recognition system must be less than 50μm. However, with the current molding or machining of lenses on the market, it is still impossible to achieve such precise design and alignment.

The present invention provides an electronic device, which can well set the microlens at a desired position even when the overall thickness of the electronic device is reduced.

An electronic device of an embodiment of the present invention includes a plurality of microlenses, a light-limiting structure, a first light-transmitting structure, and a sensing element. These microlenses are arranged in an array. The sensing element includes a plurality of sensing pixels. The sensing element, the first light-transmitting structure, the light-limiting structure, and these microlenses are sequentially stacked in a stacking direction. Each sensing pixel corresponds to at least two of these microlenses in the stacking direction.

In an embodiment of the present invention, the electronic device further includes a second light-transmitting structure, which is disposed between the microlenses and the light-limiting structure. The thickness of the second light-transmitting structure in the stacking direction falls within a range of 8 to 15 microns.

In an embodiment of the present invention, the above-mentioned second light-transmitting structure is a passivation layer.

In an embodiment of the present invention, the maximum height of the above-mentioned microlenses in the stacking direction falls within the range of 1 to 3 microns.

In an embodiment of the present invention, the above-mentioned light limiting structure is a metal layer.

In an embodiment of the present invention, the above-mentioned light-limiting structure includes a plurality of light-transmitting holes. The aperture of these light-transmitting holes falls in the range of 1 to 3 microns. Each microlens corresponds to one of the light-transmitting holes in the stacking direction.

In an embodiment of the present invention, the above-mentioned first light-transmitting structure includes a plurality of inner metal dielectric layers.

In an embodiment of the present invention, the above-mentioned first light-transmitting structure further includes an inner dielectric layer disposed between the inner metal dielectric layer and the sensing element.

In an embodiment of the present invention, the thickness of the above-mentioned first light-transmitting structure in the stacking direction falls in the range of 8 to 15 microns.

In an embodiment of the present invention, the electronic device further includes a plurality of inner metal layers and a driving element. The inner metal layers are respectively embedded in the inner metal dielectric layers. The first light-transmitting structure is arranged between the light-limiting structure and the driving element. The driving element is electrically connected to the sensing element, and is electrically connected to the light-limiting structure through these inner metal layers.

Based on the foregoing, in the electronic device of the embodiment of the present invention, since each sensing pixel corresponds to at least two of the plurality of microlenses in the stacking direction, the amount of incident light that can be received by each sensing pixel increases. Therefore, the sensing effect of the electronic device is better.

FIG. 1 is a schematic partial cross-sectional view of an electronic device according to an embodiment of the invention. FIG. 2 is a schematic diagram of a sensor pixel of an electronic device corresponding to a microlens according to an embodiment of the invention. It should be noted here that the relative thicknesses between the stacked layers in FIG. 1 and FIG. 2 are presented for clarity only, and the relative thicknesses in the drawings do not reflect the actual relative thicknesses. Referring to FIGS. 1 and 2 at the same time, an electronic device 100 according to an embodiment of the present invention includes a plurality of microlenses 110, a light limiting structure 120, a first light transmitting structure 130 and a sensing element 140. The sensing element 140, the first light-transmitting structure 130, the light-limiting structure 120, and the microlens 110 are sequentially stacked in a stacking direction D.

Specifically, the first light-transmitting structure 130, the light-limiting structure 120, and the microlens 110 are formed, for example, after the sensing element 140 is formed, and then the first light-transmitting structure 130 and the light-limiting structure are sequentially formed by a semiconductor process or a photolithography process. 120 and microlens 110. In this embodiment, the sensing element 140 includes a plurality of sensing pixels 141. The sensing element 140 can be a Complementary Metal-Oxide Semiconductor (CMOS) or a Charge Coupled Device (CCD). The microlens 110 is formed of, for example, a polymer material such as polymethylmethacrylate (PMMA) or other suitable materials.

In order for the electronic device 100 to deduct the sensing element 140, the overall thickness in the stacking direction D can be less than or equal to 50 microns, and the microlens 110 can be formed through a lithography process. In this embodiment, the microlens 110 is stacked The maximum height h in the direction D falls within the range of 1 to 3 microns. Furthermore, in order to improve the resolution of the electronic device 100, the size of each sensing pixel 141 must be less than 50 microns. However, for each microlens 110 formed by a lithography process, the size of 50 microns is too large. Therefore, in this embodiment, a plurality of microlenses 110 are arranged in an array, and each sensing pixel 141 is stacked The direction D corresponds to at least two microlenses 110 among the plurality of microlenses 110. For example, each sensing pixel 141 at least partially overlaps its corresponding at least two microlenses 110 in the stacking direction D.

FIG. 2 illustrates that a substrate 200 is provided on the electronic device 100. The substrate is, for example, a transparent display panel such as an organic light emitting diode. When the user's finger presses on the surface 201 of the substrate 200, the light beam emitted by the substrate 200 is reflected by the finger, and the reflected light beam is received by the sensing element 140 of the electronic device 100, so that the electronic device 100 can obtain a fingerprint image. FIG. 2 illustrates that each sensing pixel 141 corresponds to a 2×2 array of microlenses 110 in the stacking direction D. As shown in FIG. However, the present invention is not limited to this. Each sensing pixel 141 can correspond to m×n, 1×n, or m×1 microlens 110 arrays in the stacking direction D, where m and n are positive integers greater than or equal to 2. .

Furthermore, in this embodiment, the light limiting structure 120 is a metal layer, and the thickness of the light limiting structure 120 in the stacking direction D is less than or equal to 0.5 μm. The light limiting structure 120 includes a plurality of light transmitting holes 121. The aperture t of the light-transmitting hole 121 falls within a range of 1 to 2 microns, and each microlens 110 corresponds to one of the light-transmitting holes 121 in the stacking direction D. For example, each microlens 110 overlaps with its corresponding light-transmitting hole 121 in the stacking direction D.

In addition, in this embodiment, the first light-transmitting structure 130 includes a plurality of inter-metal dielectric layers (Inter-Metal Dielectric layer, IMD layer) 131 and an inter-layer dielectric layer (Inter-layer Dielectric layer, ILD layer) 132. The inner dielectric layer 132 is disposed between the inner metal dielectric layer 131 and the sensing element 140. The inner metal dielectric layer 131 and the inner dielectric layer 132 can be made of insulating materials such as silicon dioxide or silicon nitride, but the invention is not limited thereto. Furthermore, the inner metal dielectric layer 131 and the inner dielectric layer 132 may be formed of the same or different materials.

In this embodiment, the thickness of the first light-transmitting structure 130 in the stacking direction D falls in the range of 8 to 15 microns. For the convenience of description, FIG. 1 simply shows four metal dielectric layers 131. However, the present invention is not limited to this, and the number of metal dielectric layers 131 should be determined according to design requirements.

In addition, in this embodiment, the electronic device 100 further includes a second light-transmitting structure 150. The second light transmitting structure 150 is disposed between the micro lens 110 and the light limiting structure 120. The second light-transmitting structure 150 may be a passivation layer formed of an insulating material such as silicon oxide or silicon nitride to prevent oxidation of various components in the electronic device 100.

Based on the above, in the electronic device 100 of the embodiment of the present invention, the arrangement of the microlens 110 and the light limiting structure 120 enables the reflected light beam to be imaged on the sensing element 140 well. Although the arrangement of the microlens 110 and the light limiting structure 120 limits the light collection angle of the reflected beam and also reduces the amount of incident light, since each sensing pixel 141 corresponds to at least two of the multiple microlenses 110 in the stacking direction D Two microlenses 110 increase the amount of incident light that can be received by each sensing pixel 141. Therefore, the sensing effect of the electronic device 100 is better. Furthermore, by increasing the thickness of the second light-transmitting structure 150, the light-receiving angle of the reflected light beam can be further limited, and the optical path of the reflected light beam from the micro lens 110 to the sensing element 140 is also increased. The depth of view (DOF) of the electronic device 100. In this embodiment, the thickness of the second light-transmitting structure 150 in the stacking direction D preferably falls within the range of 8 to 15 microns.

In addition, in this embodiment, the electronic device further includes a plurality of inner metal layers 160 and a driving element 170. The first light-transmitting structure 130 is disposed between the light-limiting structure 120 and the driving element 170. The inner metal layer 160 is respectively embedded in the inner metal dielectric layer 131 and is electrically connected to the light limiting structure 120. The driving element 170 is electrically connected to the sensing element 140, and is electrically connected to the light limiting structure 120 through the inner metal layer 160. In other words, the light limiting structure 120, the inner metal layer 160, and the driving element 170 may be a part of a control circuit that controls the sensing element 140. In this embodiment, the driving element 170 may be a transistor circuit layer formed by a semiconductor process. The inner dielectric layer 132 of the first light-transmitting structure 130 covers the sensing element 140 and the driving element 170 so that other stacked layers can be sequentially stacked on the inner dielectric layer 132. The metal dielectric layer 131 of the first light-transmitting structure 130 is used to prevent the inner metal layers 160 from directly contacting each other and causing a short circuit.

In summary, in the electronic device of the embodiment of the present invention, the arrangement of the microlens and the light-limiting structure enables the reflected light beam to be imaged on the sensing element well. Furthermore, since each sensing pixel corresponds to at least two of the plurality of microlenses in the stacking direction, the amount of incident light that can be received by each sensing pixel increases. Therefore, the sensing effect of the electronic device is better. Moreover, compared with lenses formed by molding or mechanical processing, the electronic device of the embodiment of the present invention can form a microlens array in a smaller area, and each microlens can still be well placed in the desired position. Location. In addition, by increasing the thickness of the second light-transmitting structure, the light-receiving angle of the reflected beam can be further limited, and the optical path of the reflected beam from the microlens to the sensing element is also increased. At this time, the electrons are also increased. The depth of the device's image acquisition.

100: electronic device 110: Micro lens 120: limited light structure 121: light hole 130: The first light transmission structure 131: inner metal dielectric layer 132: inner dielectric layer 140: sensing element 141: Sensing pixels 150: second light transmission structure 160: inner metal layer 170: drive components 200: substrate 201: Surface D: stacking direction h: height t: width

FIG. 1 is a schematic partial cross-sectional view of an electronic device according to an embodiment of the invention. FIG. 2 is a schematic diagram of a sensor pixel of an electronic device corresponding to a microlens according to an embodiment of the invention.

110: Micro lens 120: limited light structure 121: light hole 130: The first light transmission structure 131: inner metal dielectric layer 132: inner dielectric layer 140: sensing element 141: Sensing pixels 150: second light transmission structure 160: inner metal layer 170: drive components D: stacking direction h: height t: width

Claims (10)

An electronic device, including: A plurality of microlenses, the microlenses are arranged in an array; A light-limiting structure; A first light-transmitting structure; and A sensing element, including a plurality of sensing pixels; The sensing element, the first light-transmitting structure, the light-limiting structure, and the microlenses are sequentially stacked in a stacking direction, and each sensing pixel corresponds to at least two of the microlenses in the stacking direction. lens. The electronic device according to claim 1, further comprising a second light-transmitting structure disposed between the microlenses and the light-limiting structure, and the thickness of the second light-transmitting structure in the stacking direction falls between 8 and 15 Within the range of micrometers. The electronic device according to claim 2, wherein the second light-transmitting structure is a passivation layer. The electronic device according to claim 1, wherein the maximum height of the microlenses in the stacking direction falls within a range of 1 to 3 micrometers. The electronic device according to claim 1, wherein the light limiting structure is a metal layer. The electronic device according to claim 1, wherein the light-limiting structure includes a plurality of light-transmitting holes, the apertures of the light-transmitting holes fall within a range of 1 to 2 microns, and each microlens corresponds to the stacking direction One of these light-transmitting holes. The electronic device according to claim 1, wherein the first light-transmitting structure includes a plurality of inner metal dielectric layers. The electronic device according to claim 7, wherein the first light-transmitting structure further includes an inner dielectric layer disposed between the inner metal dielectric layers and the sensing element. The electronic device according to claim 1, wherein the thickness of the first light-transmitting structure in the stacking direction falls within a range of 8 to 15 microns. The electronic device according to claim 7, further comprising: A plurality of inner metal layers are respectively embedded in the inner metal dielectric layers; and A driving element, wherein the first light-transmitting structure is disposed between the light-limiting structure and the driving element, the driving element is electrically connected to the sensing element, and the inner metal layers and the light-limiting structure are electrically connected to each other. connect.

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