CN211555920U

CN211555920U - Packaging structure of fingerprint identification chip

Info

Publication number: CN211555920U
Application number: CN202020237059.3U
Authority: CN
Inventors: 王凯厚; 杨剑宏
Original assignee: China Wafer Level CSP Co Ltd
Current assignee: China Wafer Level CSP Co Ltd
Priority date: 2020-03-02
Filing date: 2020-03-02
Publication date: 2020-09-22
Anticipated expiration: 2030-03-02

Abstract

The utility model discloses a packaging structure of fingerprint identification chip, include: the fingerprint identification chip is provided with a front surface and a back surface which are opposite, and the front surface of the fingerprint identification chip is provided with a plurality of pixel points for collecting fingerprint information; the fingerprint identification chip comprises a second light-transmitting layer, a light filter and a light shielding layer which are sequentially formed on the front surface of the fingerprint identification chip, wherein a plurality of light-transmitting holes are formed in the light shielding layer, and each light-transmitting hole corresponds to one pixel point. The utility model takes the optical filter as the blocking layer and makes the light holes on the shading layer, on one hand, the formed columnar shading body better shields and absorbs the excessive oblique light, so that the formed image of the object is clearer; on the other hand, the optical filter can filter out stray light outside the detection light band; on the other hand, the method can improve the processing efficiency and is suitable for wafer-level packaging.

Description

Packaging structure of fingerprint identification chip

Technical Field

The utility model belongs to the technical field of the semiconductor, concretely relates to fingerprint identification chip packaging structure.

Background

With the continuous progress of science and technology, more and more electronic devices are widely applied to the daily life and work of people, bring great convenience to the daily life and work of people, and become an indispensable important tool for people at present. With the increasing functions of electronic devices, the electronic devices store more and more important information, and the authentication technology of electronic devices becomes a main direction for the research and development of electronic devices.

The fingerprint has uniqueness and invariance, so that the fingerprint identification technology has the advantages of good safety, high reliability, simplicity in use and the like. Therefore, fingerprint identification technology is the mainstream technology for authentication of various electronic devices.

At present, an optical fingerprint identification chip is one of fingerprint identification chips commonly used in existing electronic devices, and collects fingerprint information of a user through a large number of photosensitive pixels (pixels) in a fingerprint identification area, and each photosensitive pixel is used as a detection. Specifically, when fingerprint identification is carried out, light irradiates to the fingerprint surface of a user and is reflected to photosensitive pixels through the fingerprint surface, the photosensitive pixels convert optical signals of fingerprints into electric signals, and fingerprint information can be acquired according to the electric signals converted by all the pixels.

When the existing optical fingerprint identification chip is packaged, a transparent cover plate is generally directly arranged on the photosensitive side. However, the transparent cover plate is completely transparent, which may cause crosstalk in the sensing results of different photosensitive pixels, and affect the fingerprint identification accuracy.

To solve the technical problem, chinese patent application CN108022904A discloses a method for packaging a fingerprint identification chip, in which a cover plate having a through hole structure is fixed on a side of a wafer facing a pixel point to avoid the crosstalk problem. The problems that exist at least include: through holes on the cover plate need to be formed in advance, and then the cover plate with the through holes is combined on the surface of the chip, but the operation process time is long, and the through holes and pixel points need to be subjected to position calibration, so that errors are easy to generate; if the through hole is manufactured after the cover plate is combined with the chip, no barrier exists between the cover plate and the chip, and pixel points below the through hole are easily damaged.

SUMMERY OF THE UTILITY MODEL

An embodiment of the utility model provides a packaging structure of fingerprint identification chip for solve among the prior art processing technology time long, the pixel receives the technical problem of harm easily, include:

a packaging structure of a fingerprint identification chip comprises:

the fingerprint identification chip is provided with a front surface and a back surface which are opposite, and the front surface of the fingerprint identification chip is provided with a plurality of pixel points for collecting fingerprint information;

the fingerprint identification chip comprises a second light-transmitting layer, a light filter and a light shielding layer which are sequentially formed on the front surface of the fingerprint identification chip, wherein a plurality of light-transmitting holes are formed in the light shielding layer, and each light-transmitting hole corresponds to one pixel point.

In one embodiment, the display device further comprises a third light-transmitting layer covering the light-transmitting hole.

In one embodiment, the display device further comprises a condensing lens formed on the surface of the third light-transmitting layer,

the condensing lens corresponds to the light transmission hole.

In one embodiment, the light shielding layer is made of monocrystalline silicon, polycrystalline silicon, amorphous silicon, silicon germanium, or silicon carbide.

In one embodiment, the first transparent layer and the light-shielding layer are fixed by adhesive.

In one embodiment, the fingerprint identification chip is an optical fingerprint identification chip.

Compared with the prior art, the utility model takes the optical filter as the blocking layer and makes the light holes on the light shielding layer, on one hand, the formed columnar light shielding body can better shield and absorb the redundant oblique light, so that the formed image of the object is clearer; on the other hand, the optical filter can filter out stray light outside the detection light band; on the other hand, the method can improve the processing efficiency and is suitable for wafer-level packaging.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a sectional view of a package structure in embodiment 1 of the present application;

fig. 2 to 9 are schematic views of intermediate structures formed by the package structure in embodiment 1 of the present application.

Detailed Description

The present invention will be more fully understood from the following detailed description, which should be read in conjunction with the accompanying drawings. Detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed embodiment.

The present embodiment provides a package structure 10, and referring to fig. 1, the package structure 10 includes a fingerprint identification chip 11 and a cover plate 12.

The fingerprint identification chip 11 has a front surface 111 and a back surface 112 opposite to each other, and the front surface has a plurality of pixel points 113 for collecting fingerprint information.

The cover 12 covers the front surface 111 of the fingerprint recognition chip 11.

In one embodiment, the fingerprint recognition chip 11 is an optical fingerprint recognition chip.

The cover plate 12 includes a transparent layer 121, an optical filter 124, a light-shielding layer 122 and a transparent layer 123 sequentially covering the front surface 111 of the fingerprint identification chip 11.

The light-transmitting layer 121 covers the front surface 111 of the fingerprint identification chip 11, and is used for protecting the front surface of the fingerprint identification chip 11 to be packaged. Since light is required to reach the pixel 113 through the transparent layer 121, the transparent layer 121 has high light transmittance and is a transparent material. Both surfaces of the transparent layer 121 are flat and smooth, and do not scatter or diffuse incident light.

Specifically, the material of the light-transmitting layer 121 may be a dry film, inorganic glass, organic glass, or other light-transmitting material with a specific strength.

In one embodiment, the transparent layer 121 and the front surface 111 of the fingerprint identification chip 11 are fixed by an adhesive.

In this embodiment, the thickness of the light-transmitting layer 121 is preferably 5 to 20 μm in consideration of both the optical properties and the adhesive properties of the light-transmitting layer 121.

The optical filter 124 is used for filtering stray light outside the detection light band, so as to reduce stray light interference and improve fingerprint identification accuracy.

The filter 124 may cover only the upper portion corresponding to the pixel 113, or may cover the entire surface of the transparent layer 121.

In one embodiment, the filter 124 and the transparent layer 121 are fixed by bonding through a DAF film.

The light-shielding layer 122 is provided with a plurality of light-transmitting holes 1221 which are vertically communicated, each light-transmitting hole 1221 corresponds to one pixel 113, and in a preferred embodiment, the axis of the light-transmitting hole 1221 coincides with the center of the pixel 113.

The light-shielding layer 122 has a low dielectric constant, and the material of the light-shielding layer 122 is preferably a silicon material, which may be monocrystalline silicon, polycrystalline silicon, amorphous silicon, silicon germanium, or silicon carbide. The light-shielding layer 122 may be formed on the surface of the light-transmitting layer 121 by physical deposition.

The light-shielding layer 122 preferably has a thickness of 4-20 μm, and when the light-transmitting holes are circular holes, the aperture is preferably 30-40 μm, and the aspect ratio is preferably 1:1 to 1.5: 1.

The light-shielding layer 122 is made of a silicon material, so that the crosstalk problem between the adjacent pixels 113 can be reduced. On the other hand, the mohs hardness of the light-shielding layer 122 made of silicon material is generally above 10, the hardness is high, the mechanical strength is high, and the thickness deformation cannot be generated when a finger presses the light-shielding layer, so that the accuracy of fingerprint identification cannot be influenced.

In a direction perpendicular to the front surface 111, a projection of the light-transmissive hole 1221 on the front surface 111 at least partially overlaps a projection of the corresponding pixel 113 on the front surface 111. In order to ensure the accuracy of fingerprint identification, the projection of the light hole 1221 on the front surface 111 may be set to completely cover the projection of the corresponding pixel 113 on the front surface 111. Optimally, the projection of the light hole 1221 on the front surface 111 may be completely overlapped with the projection of the corresponding pixel 113 on the front surface 111.

The front surface 111 includes a sensing area and a non-sensing area surrounding the sensing area. Wherein, the pixel point 113 is arranged in the sensing area; the non-sensing area is provided with a pad (not shown) electrically connected to the pixel 113, and the pad is used for electrically connecting to an external circuit.

If fingerprint identification chip 11 is the fingerprint identification chip of electric capacity type, when carrying out fingerprint identification, 113 detection capacitance values of pixel point convert the capacitance value into the signal of telecommunication, and external circuit can acquire fingerprint information according to this signal of telecommunication, carries out identity identification, and light trap 1221 is used for exposing the pixel point, light shield layer 122 has lower dielectric constant, can reduce the crosstalk problem between the adjacent pixel point, has improved fingerprint identification's accuracy.

If the fingerprint identification chip 11 is an optical fingerprint identification chip, when fingerprint identification is performed, the pixel 113 collects fingerprint information of a preset area through the corresponding light hole 1221 and collects the fingerprint information of the preset area corresponding to the light hole 1221. Because every pixel 113 is all through corresponding light trap 1221 gather the fingerprint information of the collection region that self is relative, avoided different pixel to correspond the mutual crosstalk between the preset region, and then avoided fingerprint image's distortion, further improved fingerprint identification's accuracy.

The shape of the light-transmitting hole 1221 may be a circular through hole, a square through hole, or a triangular through hole. Specifically, the shape of the light-transmitting hole 1221 may be a circular hole with the same top and bottom, a square hole with the same top and bottom, a triangular hole with the same top and bottom, or a polygon with the same top and bottom in other structures. The bottom of light trap 1221 is the opening that light trap 1221 is close to pixel 113, and the top of light trap 1221 is the opening that light trap 1221 keeps away from pixel 113.

It is easy to think that the shape of the light-transmitting hole 1221 may be a circular hole with different top and bottom, a square hole with different top and bottom, a triangular hole with different top and bottom, or a polygon with different top and bottom. At this time, the top of the light-transmissive hole 1221 is larger than the bottom of the light-transmissive hole 1221. Similarly, the bottom of the light hole 1221 is an opening of the light hole 1221 close to the pixel 113, and the top of the light hole 1221 is an opening of the light hole 1221 far from the pixel 113.

In one embodiment, the light shielding layer 122 and the optical filter 124 are fixed by bonding via a DAF film.

The transparent layer 123 covers a surface of the light-shielding layer 122 away from the front surface 111, and is used for shielding an opening of the transparent hole 1221. Since light is required to reach the pixel 113 through the transparent layer 123, the transparent layer 123 has high light transmittance and is a transparent material. The two surfaces of the transparent layer 123 are flat and smooth, and do not scatter or diffuse the incident light.

Specifically, the material of the light-transmitting layer 123 may be a dry film, inorganic glass, organic glass, or other light-transmitting material with a specific strength.

In this embodiment, the thickness of the light-transmitting layer 123 is preferably 10 to 40 μm.

In one embodiment, the transparent layer 123 and the light-shielding layer 122 are fixed by an adhesive.

The side of the transparent layer 123 away from the front surface 111 of the fingerprint identification chip 11 is provided with a plurality of condensing lenses 125, each condensing lens 125 corresponds to one transparent hole 1221, and the condensing lenses 125 are used for condensing external light to the surfaces of the corresponding pixels 113.

In one embodiment, the condensing lens 125 may be formed by photolithography and baking, and in another embodiment, the condensing lens 125 may also be formed on the surface of the transparent layer 123 by stamping.

Correspondingly, the embodiment of the invention provides a packaging method for forming the packaging structure shown in fig. 1. Please refer to fig. 2 to fig. 9, which are schematic diagrams of intermediate structures formed in the packaging process of the packaging method according to an embodiment of the present invention.

Step s 1: referring to fig. 2 and 3, a wafer 100 to be packaged is provided, wherein fig. 2 is a schematic top view of the wafer 100 to be packaged, and fig. 3 is a cross-sectional view taken along a-a in fig. 2.

The wafer 100 to be packaged has a front side 111 and a back side 112 opposite to the front side 111. The wafer 100 includes a plurality of fingerprint identification chips 11 arranged in an array. Each adjacent fingerprint identification chip 11 has a plurality of pixel points 13 for collecting fingerprint information. The pixel 13 is located on the front side 111. The adjacent fingerprint identification chips 11 have a cutting channel 120 therebetween to facilitate a cutting process in a subsequent cutting process.

The first surface 111 includes a sensing region and a non-sensing region surrounding the sensing region, the pixel 113 is disposed in the sensing region, and a pad (not shown) is disposed in the non-sensing region and electrically connected to the pixel 113, and the pad is used for electrically connecting to an external circuit.

It should be noted that the cutting channel 120 between two adjacent fingerprint identification chips 11 is only a margin area reserved between two fingerprint identification chips 11 for cutting, and there is no actual boundary line between the cutting channel 120 and the fingerprint identification chips 11 on both sides.

Step s 2: referring to fig. 4, a front surface 111 of the wafer 100 to be packaged is covered with a transparent layer 121. In this step, a transparent layer 121 is fixed on the surface of the wafer 100 to be packaged by adhesive.

Step s 3: referring to fig. 5, the surface of the light-transmitting layer 121 is covered with the optical filter 124.

Step s 4: referring to fig. 6, the light-shielding layer 122 is covered on the surface of the filter 124, and in this step, the light-shielding layer 122 is fixed on the surface of the filter 124 by adhesive. For example, an adhesive layer may be formed on the surface of the light shielding layer 122 facing the optical filter 124 and/or the optical filter 124 by a spraying, spin coating or pasting process, and then the optical filter 124 and the light shielding layer 122 are pressed together and bonded by the adhesive layer. The adhesive layer can realize the adhesive function and also can play the insulating and sealing functions. The adhesive layer may be a polymer adhesive material, such as a polymer material, e.g., silicone, epoxy, benzocyclobutene, etc.

Step s 5: referring to fig. 7, a plurality of light holes 1221 are etched in the light-shielding layer 122 using the optical filter 124 as a blocking layer.

Step s 6: referring to fig. 8, the light-transmitting layer 123 is covered on the surface of the light-shielding layer 122, and in this step, the light-transmitting layer 123 is fixed on the surface of the light-shielding layer 122 by an adhesive. The transparent layer 123 may cover only the top opening of the transparent hole 1221, or may cover the entire surface of the light-shielding layer 122.

Step s 7: referring to fig. 9, a plurality of condensing lenses 125 are formed on the surface of the transparent layer 123, and each condensing lens 125 corresponds to one transparent hole 1221.

Step s 8: the wafer 100, the light-transmitting layer 121, the optical filter 124, the light-shielding layer 122 and the light-transmitting layer 123 are divided by a cutting process, and when the wafer is cut, the wafer is cut along the direction of the cutting channels 120, so that the package structures 10 of the fingerprint identification chips 11 are formed. The cutting can be performed by a slicing knife or a laser cutting, and the slicing knife can be performed by a metal knife or a resin knife.

In the whole packaging process, the processes of wafer thinning, bonding pad manufacturing, wiring layer manufacturing and the like can be included, and the scheme is not repeated.

In addition, after the wafer 200 to be packaged is packaged, the chip package structure obtained by subsequent dicing can be connected to an external circuit through an external bump (not shown).

In summary, the utility model uses the optical filter as the blocking layer and makes the light hole on the shading layer, on one hand, the formed columnar shading body can better shade and absorb the excessive oblique light, so that the object forming image is clearer; on the other hand, the optical filter can filter out stray light outside the detection light band; on the other hand, the method can improve the processing efficiency and is suitable for wafer-level packaging.

The aspects, embodiments, features and examples of the present invention should be considered illustrative in all respects and not intended to be limiting, the scope of the invention being defined only by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed invention.

The use of headings and chapters in this application is not meant to limit the invention; each section may apply to any aspect, embodiment, or feature of the present invention.

Throughout this application, where a composition is described as having, containing, or comprising specific components or where a process is described as having, containing, or comprising specific process steps, it is contemplated that the compositions taught by the present invention also consist essentially of, or consist of, the recited components, and that the processes taught by the present invention also consist essentially of, or consist of, the recited process steps.

In this application, where an element or component is referred to as being included in and/or selected from a list of recited elements or components, it is understood that the element or component can be any one of the recited elements or components and can be selected from a group consisting of two or more of the recited elements or components. Moreover, it should be understood that elements and/or features of the compositions, apparatus, or methods described herein may be combined in various ways, whether explicitly described or implicitly described herein, without departing from the spirit and scope of the present teachings.

Unless specifically stated otherwise, use of the terms "comprising", "including", "having" or "having" is generally to be understood as open-ended and not limiting.

The use of the singular herein includes the plural (and vice versa) unless specifically stated otherwise. Furthermore, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. In addition, where the term "about" is used before a quantity, the teachings of the present invention include the particular quantity itself unless specifically stated otherwise.

It should be understood that the order of steps or the order in which particular actions are performed is not critical, so long as the teachings of the present invention remain operable. Further, two or more steps or actions may be performed simultaneously.

It is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention, while eliminating, for purposes of clarity, other elements. However, those skilled in the art will recognize that these and other elements may be desirable. However, because such elements are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements is not provided herein. It should be understood that the figures are presented for illustrative purposes and not as construction diagrams. The omission of details and modifications or alternative embodiments is within the scope of one skilled in the art.

It is to be understood that in certain aspects of the present invention, a single component may be replaced by multiple components and that multiple components may be replaced by a single component to provide an element or structure or to perform a given function or functions. Such substitutions are considered to be within the scope of the present invention, except where such substitution would not operate to practice a particular embodiment of the invention.

While the invention has been described with reference to illustrative embodiments, it will be understood by those skilled in the art that various other changes, omissions and/or additions may be made and substantial equivalents may be substituted for elements thereof without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. Moreover, unless specifically stated any use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another.

Claims

1. A packaging structure of a fingerprint identification chip is characterized by comprising:

2. The package structure of the fingerprint identification chip of claim 1, further comprising a third transparent layer covering the transparent hole.

3. The package structure of fingerprint identification chip of claim 1, further comprising a condensing lens formed on the surface of the third transparent layer,

the condensing lens corresponds to the light transmission hole.

4. The package structure of the fingerprint identification chip of claim 1, wherein the light shielding layer is made of monocrystalline silicon, polycrystalline silicon, amorphous silicon, silicon germanium, or silicon carbide.

5. The package structure of the fingerprint identification chip of claim 1, wherein the first transparent layer and the light shielding layer are fixed by adhesive.

6. The package structure of fingerprint identification chip of claim 1, wherein said fingerprint identification chip is an optical type fingerprint identification chip.