WO2022242050A1 - Packaging structure for image sensor chip - Google Patents

Abstract

Provided in the present invention is a packaging structure for an image sensor chip. The packaging structure comprises a transparent substrate which has a first surface and a second surface opposite each other, and is divided into a light-transmitting region and a non-light-transmitting region, the non-light-transmitting region on the second surface of the transparent substrate being provided with a wiring circuit; and an image sensor chip which is arranged on the second surface of the transparent substrate in a flipped-over manner and is electrically connected to the wiring circuit, wherein the image sensor chip comprises a sensing region provided towards the transparent substrate, the sensing region corresponding to the light-transmitting region; and at least one lens is formed in the light-transmitting region on the first surface and the second surface of the transparent substrate, so as to form a biconvex lens structure, such that aberrations can be eliminated and the thickness of the packaging structure can be reduced.

Description

Image sensor chip packaging structure

This application claims the priority of a Chinese patent application with an application date of May 18, 2021, an application number of 202110537359.2, and an invention title of "Image Sensor Chip Packaging Structure", the entire contents of which are incorporated in this application by reference.

technical field

The invention relates to the technical field of semiconductors, in particular to an image sensor chip packaging structure.

Background technique

With the continuous development of science and technology, more and more electronic devices are integrated with image sensing components such as lenses and image sensor chips to enable electronic devices to have biometric functions. Therefore, image sensor chips have been used more and more widely. . However, with the development of chip packaging structure towards miniaturization, the luminous flux that the image sensor chip can receive decreases, which affects the imaging effect. In the prior art, in order to increase the luminous flux, multiple sets of stacked lens structures are usually provided, but the stacked lens structure will undoubtedly greatly increase the volume of the package structure, which is not conducive to the miniaturization of the package structure of the image sensor chip.

Contents of the invention

The object of the present invention is to provide an image sensor chip packaging structure.

The present invention provides an image sensor chip packaging structure, including:

A transparent substrate, which has opposite first and second surfaces, the transparent substrate is divided into a light-transmitting area and a non-transmitting area surrounding the light-transmitting area, and the non-transmitting area on the second surface of the transparent substrate The optical area is equipped with wiring lines;

An image sensor chip, which is flip-chip mounted on the second surface of the transparent substrate and electrically connected to the wiring lines, the image sensor chip includes a sensing area set toward the transparent substrate, the sensing area Corresponding to the light-transmitting area;

At least one lens is formed on the transparent substrate on the first surface and the light-transmitting area on the second surface respectively.

As a further improvement of the present invention, a plurality of lenses are formed on the transparent substrate on the first surface and the second surface of the transparent substrate respectively, and the plurality of lenses form a densely arranged lens array.

As a further improvement of the present invention, the lens or the lens array at least completely covers the sensing area.

As a further improvement of the present invention, the lens is a nanoimprint microlens.

As a further improvement of the present invention, the first surface and/or the second surface of the transparent substrate is further coated with a filter layer, and the filter layer is located between the transparent substrate and the lens.

As a further improvement of the present invention, the thickness of the filter layer ranges from 100 μm to 150 μm.

As a further improvement of the present invention, it also includes an insulating layer covering the wiring lines, and the insulating layer exposes a part of the wiring lines to form a welding pad.

As a further improvement of the present invention, the welding pad includes a first welding pad and a second welding pad located outside the first welding pad.

As a further improvement of the present invention, a conductive bump is further included, one end of the conductive bump is electrically connected to the image sensor chip, and the other end is electrically connected to the first welding pad.

As a further improvement of the present invention, a sealant is provided on the periphery of the image sensor chip, and the sealant seals between the image sensor chip and the insulating layer.

The beneficial effect of the present invention is that a biconvex lens structure is formed by arranging lenses on both sides of the transparent substrate at the same time. Both surfaces of the upper and lower lenses have a certain radius of curvature to provide positive optical power, and there is an additional effective curvature when focusing the optical path. Variables can cooperate with each other to better eliminate aberrations. In addition, the lens provided on the second surface of the transparent substrate is located in the cavity between the transparent substrate and the image sensor chip, which does not increase the thickness of the package structure, and because it can provide a certain optical power, it can reduce the The curvature of the lens located on the first surface of the transparent substrate is required to reduce its thickness, thereby reducing the thickness of the packaging structure as a whole.

Description of drawings

FIG. 1 is a schematic diagram of an image sensor chip package structure in an embodiment of the present invention.

FIG. 2 is a schematic diagram of the packaging structure of an image sensor chip in another embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solution and advantages of the present application clearer, the following will clearly and completely describe the technical solution of the present application in combination with specific implementation methods of the present application and corresponding drawings. Apparently, the described implementations are only some of the implementations of this application, not all of them. Based on the implementation manners in this application, all other implementation manners obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

For the convenience of description, terms representing relative positions in space are used herein for description, such as "upper", "lower", "rear", "front", etc., which are used to describe the relative position of one unit or feature shown in the drawings relative to another. A unit or feature relationship. Spatially relative terms may encompass different orientations of the device in use or operation other than the orientation shown in the figures. For example, if the device in the figures is turned over, elements described as "below" or "above" other elements or features would then be oriented "below" or "above" the other elements or features. Thus, the exemplary term "below" can encompass both a spatial orientation of below and above.

As shown in FIG. 1 , the present invention provides an image sensor chip packaging structure, which includes: a transparent substrate 1, an image sensor chip 2, and a lens 3 formed on the transparent substrate 1.

A transparent substrate 1, which has opposite first and second surfaces, the transparent substrate 1 is divided into a light-transmitting area 1a and a non-light-transmitting area 1b surrounding the light-transmitting area 1a, and the non-light-transmitting area on the second surface of the transparent substrate 1 1b is provided with wiring lines 4 . The transparent substrate 1 is made of inorganic glass, plexiglass and other light-transmitting materials with specific strength. It is functionally divided into a light-transmitting area 1a and a non-light-transmitting area 1b. The light-transmitting area 1a is located on the image sensor chip 2. It plays the role of protecting and transmitting light to the image sensor chip 2 . The upper and lower surfaces of the transparent substrate 1 are flat and smooth to avoid scattering and diffuse reflection of the incident light, thereby affecting the sensing accuracy of the image sensor chip 2 . The non-light-transmitting area 1 b is used for setting wiring lines 4 , insulating layers 5 and other structures to provide electrical support and structural support for the image sensor chip 2 .

The wiring circuit 4 may include, for example, at least one of electronic components such as resistors, inductors, capacitors, integrated circuit blocks, and optical components, and the wiring circuit 4 may also include connecting wires between electronic components.

The image sensor chip 2 is flip-chip mounted on the second surface of the transparent substrate 1 and is electrically connected to the wiring circuit 4. The image sensor chip 2 includes a sensing region 21 disposed toward the transparent substrate 1. The sensing region 21 is connected to the light-transmitting Region 1a corresponds. A third welding pad 22 is provided outside the photosensitive area, and the third welding pad 22 is electrically coupled with the sensing area 21 for electrically connecting the image sensor chip 2 with the wiring line 4 .

The sensing area 21 may include a plurality of photodiode arrays arranged to convert light signals irradiated onto the sensing area 21 into electrical signals. The third pad 22 serves as the input and output terminals for connecting the devices in the sensing area 21 to external circuits.

The transparent substrate 1 is respectively formed with at least one lens 3 at the light-transmitting area 1a on its first and second surfaces. By setting the lens 3 on the transparent substrate, it plays a role in focusing the light. In the light-transmitting area 1a When the size is constant, the amount of incoming light can be increased to improve the imaging effect of the image sensor chip 2 . Further, the lenses 3 are arranged on both sides of the transparent substrate 1. Compared with the plano-convex lens structure formed by the lens 3 arranged on one side, the lenses 3 are arranged on both sides of the transparent substrate 1 to form a biconvex lens structure. One surface of the plano-convex lens structure is a plane, and the other surface is a curved surface, and only one surface can provide positive optical power. Compared with the plano-convex lens structure, the two surfaces of the bi-convex lens structure have a certain radius of curvature to provide positive optical focus. degree, there is an additional effective curvature variable when focusing the optical path, which can cooperate with each other to better eliminate aberrations. In addition, the lens 3 provided on the second surface of the transparent substrate 1 is located in the cavity between the transparent substrate 1 and the image sensor chip 2, which does not increase the thickness of the packaging structure, and because it can provide a certain optical power, Therefore, the requirement on the curvature of the lens 3 located on the first surface of the transparent substrate 1 can be reduced to reduce its thickness, thereby reducing the thickness of the packaging structure as a whole.

As shown in Figures 1 and 2, according to the optical path requirements of different chips, one lens 3 can be respectively arranged on the first and second surfaces of the transparent substrate 1, or a plurality of lenses 3 can be arranged to form a densely arranged lens 3 array, each Parameters such as curvature and thickness of the lens 3 are specifically adjusted according to factors such as the specific size of the package structure, which is not specifically limited in the present invention.

Further, a single lens 3 or an array of lenses 3 at least completely covers the sensing area 21, and the lens 3 fully covers the light-transmitting area 1a to fully use the space of the light-transmitting area 1a, thereby further improving the imaging quality of the image sensor chip 2.

Furthermore, the lens 3 is a nanoimprint microlens 3, and the structure of the lens 3 is directly formed on the transparent substrate 1 by nanoimprinting technology, without additional lens 3 layers, and the structure of the double-sided lens 3 on the transparent substrate 1 is easy to realize. In some other embodiments of the present invention, the lens 3 may also be formed by baking and other processes.

In some embodiments of the present invention, the first surface and/or the second surface of the transparent substrate 1 is covered with a filter layer 6 , and the filter layer 6 is located between the transparent substrate 1 and the lens 3 . The optical filter layer 6 may be, for example, an infrared filter layer 6, which can transmit infrared light and filter light in other wavelength bands. The filter layer 6 is located in the light-transmitting area 1a and the non-light-transmitting area 1b on the transparent substrate 1, that is to say, the filter layer 6 covers the light-transmitting area 1a, so the light transmitted to the image sensor chip 2 will pass through the filter Layer 6, which is conducive to improving the quality of image sensing. The filter layer 6 can be plated on the surface of the transparent substrate 1 by a process such as vacuum sputtering.

Further, the thickness of the filter layer 6 ranges from 100 μm to 150 μm, which is not only conducive to thinning the packaging structure of the image sensor chip 2 , but also can ensure the filtering effect of the filter layer 6 .

In some embodiments of the present invention, the packaging structure further includes an insulating layer 5, the insulating layer 5 is disposed on the second surface of the transparent substrate 1, and covers the wiring lines 4, and the insulating layer 5 exposes a part of the wiring lines 4 to form a soldering pad, insulating The layer 5 includes an opening, and the opening exposes a part of the wiring line 4 , thereby forming a pad, and the pad includes a first pad 41 and a second pad 42 located outside the first pad 41 . The first pad 41 is used to electrically connect the image sensor chip 2 , and the second pad 42 is used to electrically connect the wiring circuit 4 to the outside. By setting the insulating layer 5 covering the wiring line 4, on the one hand, it is beneficial to avoid short-circuiting between other parts of the wiring line 4 except the welding pad and the external circuit; The packaging structure of the image sensor chip 2 provides support to improve the stability of the packaging structure of the image sensor chip 2 .

The image sensor chip 2 is electrically connected to the wiring line 4 through the conductive bump 23 , one end of the conductive bump 23 is electrically connected to the image sensor chip 2 , and the other end is electrically connected to the first pad 41 . The material of the conductive bump 23 can be, for example, metals such as gold, silver, aluminum, titanium or copper, preferably gold. In some other embodiments of the present invention, the electrical connection with the wiring circuit 4 may also be realized by means of metal bonding or the like.

In some embodiments of the present invention, the periphery of the image sensor chip 2 is provided with a sealant 7 , and the sealant 7 seals between the image sensor chip 2 and the insulating layer 5 . By setting the sealant 7, on the one hand, it is possible to prevent the sensing area 21 of the image sensor chip 2 from being polluted by external water vapor; Comes off on line 4.

In summary, the present invention forms a double-convex lens structure by setting lenses on both sides of the transparent substrate. Both surfaces of the upper and lower lenses have a certain radius of curvature to provide positive optical power, and an effective lens is added when focusing the optical path. Curvature variables can cooperate with each other to better eliminate aberrations. In addition, the lens provided on the second surface of the transparent substrate is located in the cavity between the transparent substrate and the image sensor chip, which does not increase the thickness of the package structure, and because it can provide a certain optical power, it can reduce the The curvature of the lens located on the first surface of the transparent substrate is required to reduce its thickness, thereby reducing the thickness of the packaging structure as a whole.

It should be understood that although this description is described according to implementation modes, not each implementation mode only includes an independent technical solution. The technical solutions in the embodiments can also be properly combined to form other embodiments that can be understood by those skilled in the art.

The series of detailed descriptions listed above are only specific descriptions of feasible implementations of the present invention, and are not intended to limit the scope of protection of the present invention. Any equivalent implementation or change that does not depart from the technical spirit of the present invention All should be included within the protection scope of the present invention.

Claims (10)

1. An image sensor chip packaging structure, comprising:

   A transparent substrate, which has opposite first and second surfaces, the transparent substrate is divided into a light-transmitting area and a non-transmitting area surrounding the light-transmitting area, and the non-transmitting area on the second surface of the transparent substrate The optical area is equipped with wiring lines;

   An image sensor chip, which is flip-chip mounted on the second surface of the transparent substrate and electrically connected to the wiring lines, the image sensor chip includes a sensing area set toward the transparent substrate, the sensing area Corresponding to the light-transmitting area;

   It is characterized in that,

   At least one lens is formed on the transparent substrate on the first surface and the light-transmitting area on the second surface respectively.
2. The image sensor chip packaging structure according to claim 1, characterized in that,

   A plurality of lenses are formed on the transparent areas of the first surface and the second surface of the transparent substrate respectively, and the plurality of lenses form a densely arranged lens array.
3. The image sensor chip package structure according to claim 2, wherein the lens or the lens array at least completely covers the sensing area.
4. The image sensor chip package structure according to claim 3, wherein the lens is a nanoimprinted microlens.
5. The image sensor chip packaging structure according to claim 1, characterized in that, the first surface and/or the second surface of the transparent substrate is also covered with a filter layer, and the filter layer is located between the transparent substrate and the transparent substrate. between the lenses.
6. The image sensor chip package structure according to claim 5, wherein the thickness of the filter layer is in a range of 100 μm-150 μm.
7. The image sensor chip package structure according to claim 1, further comprising an insulating layer covering the wiring lines, and the insulating layer exposes a part of the wiring lines to form a soldering pad.
8. The package structure of the image sensor chip according to claim 7, wherein the bonding pads include a first bonding pad and a second bonding pad located outside the first bonding pad.
9. The image sensor chip packaging structure according to claim 8, further comprising a conductive bump, one end of the conductive bump is electrically connected to the image sensor chip, and the other end is electrically connected to the first pad. electrical connection.
10. The packaging structure of the image sensor chip according to claim 7, wherein a sealant is provided on the periphery of the image sensor chip, and the sealant seals between the image sensor chip and the insulating layer.

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