Packaging structure and packaging method of optical fingerprint chip

Abstract

The present invention discloses a packaging structure and packaging method of an optical fingerprint chip, the packaging structure comprising: an optical fingerprint chip, the optical fingerprint chip having a first surface and a second surface relative to each other, the first surface comprising a plurality of photosensitive pixels and pads electrically connected to the photosensitive pixels; a silicon cover plate, the silicon cover plate being bonded and fixed to the first surface, the silicon cover plate having a plurality of through holes arranged one by one relative to the photosensitive pixels; wherein the photosensitive pixels of the optical fingerprint chip are used as reference positions for the silicon cover plate to form the through holes. The packaging structure adopts a silicon cover plate with through holes as a collimator, fixes the silicon cover plate on the optical fingerprint chip, and can use the optical fingerprint chip as a reference standard for alignment, the alignment process is simple, and the manufacturing cost is reduced.

Description

Technical Field

[0001] The present invention relates to the field of chip packaging technology, and more specifically, to a packaging structure and a packaging method of an optical fingerprint chip. Background Art

[0002] With the continuous development of science and technology, more and more electronic devices are widely used in people's daily life and work, bringing great convenience to people's daily life and work, and becoming an indispensable and important tool for people today.

[0003] At present, the functions of electronic devices are becoming increasingly diverse, and more and more personal information of users is stored. In order to ensure the security of user personal information, the identity recognition function of electronic devices has become an important function of today's electronic devices. Fingerprint recognition has many advantages such as uniqueness, high security and simple operation, and has become the main way for identity recognition of current electronic devices.

[0004] Integrating optical fingerprint chips in electronic devices is currently a way for electronic devices to realize fingerprint recognition functions. In the existing packaging structure of optical fingerprint chips, the alignment process of the optical fingerprint chip and the collimator is complex and the manufacturing cost is high. Summary of the invention

[0005] In order to solve the above problems, the technical solution of the present invention provides a packaging structure and a packaging method of an optical fingerprint chip, wherein a silicon cover plate with a through hole is used as a collimator, and the silicon cover plate is fixed on the optical fingerprint chip. The optical fingerprint chip can be used as a reference standard for alignment, and the alignment process is simple, thereby reducing the production cost.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A packaging structure of an optical fingerprint chip, the packaging structure comprising:

[0008] An optical fingerprint chip, wherein the optical fingerprint chip has a first surface and a second surface opposite to each other, wherein the first surface includes a plurality of photosensitive pixels and pads electrically connected to the photosensitive pixels;

[0009] A silicon cover plate, the silicon cover plate is attached and fixed on the first surface, and the silicon cover plate has a plurality of through holes arranged one by one opposite to the photosensitive pixels;

[0010] Wherein, the photosensitive pixels of the optical fingerprint chip are used as reference positions for forming the through holes in the silicon cover plate.

[0011] Preferably, in the above packaging structure, the first surface includes a photosensitive area and a peripheral area surrounding the photosensitive area, the photosensitive pixels are arranged in the photosensitive area, and the pads are arranged in the peripheral area;

[0012] The silicon cover plate at least covers the photosensitive area.

[0013] Preferably, in the above packaging structure, it further comprises: an infrared filter arranged on a surface of the silicon cover plate facing away from the optical fingerprint chip;

[0014] The silicon cover plate is directly attached to and fixed on the first surface.

[0015] Preferably, in the above packaging structure, the silicon cover plate covers the photosensitive area and exposes the peripheral area to expose the welding pad;

[0016] The welding pad is electrically connected to an external circuit through a wire.

[0017] Preferably, in the above packaging structure, a circuit board is fixed to the second surface of the optical fingerprint chip, and the circuit board is used to connect to an external circuit;

[0018] The wire is connected to the circuit board.

[0019] Preferably, in the above-mentioned packaging structure, the packaging structure further comprises a packaging adhesive layer covering the peripheral area, and the packaging adhesive layer covers the wire and the welding pad.

[0020] Preferably, in the above packaging structure, the packaging glue layer contacts the side surface of the silicon cover plate, and a surface of the silicon cover plate facing away from the optical fingerprint chip does not exceed a surface of the packaging glue layer facing away from the optical fingerprint chip.

[0021] Preferably, in the above packaging structure, the silicon cover completely covers the first surface;

[0022] The second surface is provided with a back-side interconnection structure, and the optical fingerprint chip is electrically connected to an external circuit through the back-side interconnection structure.

[0023] Preferably, in the above packaging structure, an infrared filter is bonded and fixed to the first surface;

[0024] The silicon cover plate is bonded and fixed to a surface of the infrared filter on a side facing away from the optical fingerprint.

[0025] Preferably, in the above packaging structure, the infrared filter completely covers the first surface; the periphery of the infrared filter and the periphery of the silicon cover plate are aligned with the periphery of the optical fingerprint chip.

[0026] Preferably, in the above packaging structure, the silicon cover is fixed to the first surface by bonding with transparent optical adhesive.

[0027] The present invention also provides a packaging method for an optical fingerprint chip, the packaging method comprising:

[0028] A wafer is provided, wherein the wafer comprises a plurality of optical fingerprint chips, wherein cutting channels are provided between the optical fingerprint chips; the optical fingerprint chip comprises a first surface and a second surface opposite to each other, wherein the first surface comprises a plurality of photosensitive pixels and pads electrically connected to the photosensitive pixels;

[0029] A silicon cover plate is attached and fixed on the wafer, wherein the silicon cover plate covers the first surface of all the optical fingerprint chips;

[0030] Taking the photosensitive pixels of the optical fingerprint chip as reference positions, a plurality of through holes corresponding to the photosensitive pixels are formed on the silicon cover plate;

[0031] The wafer and the silicon cover plate are cut based on the cutting channel to form a packaging structure of multiple optical fingerprint chips.

[0032] Preferably, in the above packaging method, after the silicon cover plate is attached and fixed on the wafer and before the through hole is formed, the packaging method further comprises:

[0033] A surface of the silicon cover plate facing away from the wafer and a surface of the wafer facing away from the silicon cover plate are thinned respectively.

[0034] Preferably, in the above packaging method, the first surface includes a photosensitive area and a peripheral area surrounding the photosensitive area, the photosensitive pixels are arranged in the photosensitive area, and the bonding pads are arranged in the peripheral area.

[0035] Preferably, in the above packaging method, the silicon cover plate is directly bonded and fixed to the surface of the wafer;

[0036] After forming the through hole and before performing the cutting process, the packaging method further includes:

[0037] The silicon cover plate is etched to expose the pad.

[0038] Preferably, in the above packaging method, after the cutting process is performed, the packaging method further comprises:

[0039] An infrared filter is bonded and fixed to the surface of the silicon cover plate on one side facing away from the optical fingerprint chip.

[0040] Preferably, in the above packaging method, after the cutting process is performed, the packaging method further comprises:

[0041] The second surface of the optical fingerprint chip is attached and fixed to a circuit board, the pad is electrically connected to the circuit board through a conductive wire, and the circuit board is used to be electrically connected to an external circuit.

[0042] Preferably, in the above packaging method, after the cutting process is performed, the packaging method further comprises:

[0043] A packaging glue layer is disposed in the peripheral area, and the packaging glue layer covers the wires and the welding pads.

[0044] Preferably, in the above packaging method, the packaging glue layer contacts the side surface of the silicon cover plate, and the side surface of the silicon cover plate facing away from the optical fingerprint chip does not exceed the side surface of the packaging glue layer facing away from the optical fingerprint chip.

[0045] Preferably, in the above packaging method, after the cutting process is performed, in each of the packaging structures, the silicon cover plate completely covers the first surface;

[0046] Before performing the cutting process, the packaging method further includes:

[0047] A backside interconnection structure is formed on the second surface, and the optical fingerprint chip is electrically connected to an external circuit through the backside interconnection structure.

[0048] Preferably, in the above packaging method, before fixing the silicon cover plate, the method further comprises:

[0049] An infrared filter is attached and fixed on the surface of the wafer, and the infrared filter covers all the optical fingerprint chips.

[0050] Preferably, in the above packaging method, the step of attaching and fixing the silicon cover plate on the wafer comprises:

[0051] The silicon cover plate is bonded and fixed to the wafer by transparent optical adhesive.

[0052] Preferably, in the above packaging method, before the cutting process is performed, the packaging method further comprises:

[0053] The transparent optical glue in the through hole is removed.

[0054] It can be known from the above description that in the packaging structure and packaging method of the optical fingerprint chip provided by the technical solution of the present invention, the packaging structure includes: an optical fingerprint chip, the optical fingerprint chip has a first surface and a second surface relative to each other, the first surface includes a plurality of photosensitive pixels and a pad electrically connected to the photosensitive pixels; a silicon cover plate, the silicon cover plate is bonded and fixed to the first surface, the silicon cover plate has a plurality of through holes arranged one by one opposite to the photosensitive pixels; wherein the photosensitive pixels of the optical fingerprint chip are used as reference positions for the silicon cover plate to form the through holes. The packaging structure uses a silicon cover plate with through holes as a collimator, fixes the silicon cover plate on the optical fingerprint chip, and can use the optical fingerprint chip as a reference standard for alignment. The alignment process is simple, and the manufacturing cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0056] Figure 1 This is a schematic diagram of a common packaging structure of an optical fingerprint chip;

[0057] Figure 2 A schematic diagram of a packaging structure of an optical fingerprint chip provided by an embodiment of the present invention;

[0058] Figure 3 for Figure 2 A schematic diagram of the structure of the photosensitive chip in the package structure shown;

[0059] Figure 4 A schematic diagram of another packaging structure of an optical fingerprint chip provided by an embodiment of the present invention;

[0060] Figure 5 for Figure 4 A schematic diagram of the structure of the optical fingerprint chip in the package structure shown;

[0061] Figure 6-Figure 15 A schematic diagram of a packaging method according to an embodiment of the present invention;

[0062] Figure 16-Figure 24 A schematic flow chart of another packaging method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0063] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0064] refer to Figure 1 , Figure 1 The schematic diagram of the structure of a common optical fingerprint chip packaging structure includes: an optical fingerprint chip 12, the optical fingerprint chip has a front side and a back side opposite to each other, the back side is fixed to the surface of the circuit board 11, the front side has a photosensitive area 121 and pads 122 located on both sides of the photosensitive area 121, the photosensitive area 121 has a plurality of photosensitive pixels, and the photosensitive pixels are connected to the pads 122. The pads 122 are connected to the interconnection circuit on the circuit board 11 through the wire 15, so as to be connected to the external circuit through the interconnection circuit.

[0065] In order to reduce the crosstalk problem of the photosensitive pixels 121, it is necessary to fix the collimator 13 on the light-incident side of the optical fingerprint chip 12. The collimator 13 has a plurality of through holes 141 corresponding to the photosensitive pixels. In the prior art, the collimator is generally attached to the surface of the cover plate 14, and the cover plate is fixed on the top of the optical fingerprint chip 12 by a bracket.

[0066] Figure 1 The packaging structure shown has high requirements on the distance accuracy between the collimator 13 and the optical fingerprint chip 12 when they are aligned. Moreover, since the collimator 13 is fixed on the cover plate 14 and then relatively fixed to the optical fingerprint chip 12 through a bracket, the more fixing processes in the middle will increase the alignment accuracy of the collimator 13 and the optical fingerprint chip 12, resulting in high requirements on the alignment accuracy during the packaging process, and the need to use a high-precision alignment device, which has a high manufacturing cost.

[0067] In order to solve the above problems, an embodiment of the present invention provides a packaging structure and a packaging method of an optical fingerprint chip. The packaging structure adopts a silicon cover plate with a through hole as a collimator, and the silicon cover plate is fixed on the optical fingerprint chip. The optical fingerprint chip can be used as an alignment reference standard. There is no need to fix the silicon cover plate with a bracket. The alignment process is simple and the production cost is reduced.

[0068] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0069] refer to Figure 2 and Figure 3 , Figure 2A schematic diagram of a packaging structure of an optical fingerprint chip provided by an embodiment of the present invention, Figure 3 for Figure 2 The schematic diagram of the structure of the photosensitive chip in the packaging structure shown, the packaging structure includes: an optical fingerprint chip 21, the optical fingerprint chip 21 has a first surface and a second surface relative to each other, the first surface includes a plurality of photosensitive pixels and a pad 212 electrically connected to the photosensitive pixels; a silicon cover plate 23, the silicon cover plate 23 is bonded and fixed to the first surface, the silicon cover plate 23 has a plurality of through holes 231 arranged one by one opposite to the photosensitive pixels; wherein the photosensitive pixels of the optical fingerprint chip 21 are used as reference positions for forming the through holes 231 on the silicon cover plate 23. Figure 2 The photosensitive pixels are not shown.

[0070] exist Figure 2 In the illustrated embodiment, the optical fingerprint chip 21 includes a photosensitive area and a peripheral area surrounding the photosensitive area, the photosensitive pixels are arranged in the photosensitive area, and the pads 212 are arranged in the peripheral area; the silicon cover plate 23 at least covers the photosensitive area.

[0071] Optionally, a protective layer 300 is included, and the protective layer 300 covers the photosensitive pixel. The silicon cover plate 23 is arranged on the surface of the protective layer 300 and is attached and fixed to the protective layer 300. The protective layer 300 has an opening to expose the pad 212, so that the pad 212 can be electrically connected to other components. Figure 3 The photosensitive pixels are not shown.

[0072] exist Figure 2 In the method, the packaging structure also includes: an infrared filter 24 arranged on the surface of the silicon cover plate 23 on the side away from the optical fingerprint chip 21. The silicon cover plate 23 is directly bonded and fixed to the first surface. The position where the silicon cover plate is not provided with the through hole 231 can pass infrared light but cannot pass visible light. Therefore, the infrared filter 24 can filter out infrared light and retain visible light. Then, the through hole 231 can make the visible light incident at a small angle incident to the photosensitive pixel corresponding to the through hole, thereby avoiding the crosstalk problem between different photosensitive pixels.

[0073] The silicon cover plate 23 covers the photosensitive area and exposes the peripheral area to expose the pad 212; the pad 212 is electrically connected to the external circuit through the wire 26. In order to facilitate the connection with the external circuit and package and protect the optical fingerprint chip 21, a circuit board 22 is fixed to the second surface of the optical fingerprint chip 21, and the circuit board 22 is used to connect to the external circuit; the wire 26 is connected to the circuit board 22, so that the optical fingerprint chip 21 is connected to the external circuit through the circuit board 22.

[0074] The packaging structure further includes a packaging glue layer 25 covering the peripheral area, and the packaging glue layer 25 covers the wire 26 and the pad 212. The packaging glue layer 25 can seal and protect the wire 26 and the pad 212, and can also seal the junction between the silicon cover plate 23 and the optical fingerprint chip 21.

[0075] The encapsulation glue layer 25 contacts the side of the silicon cover plate 23, and the side surface of the silicon cover plate 23 facing away from the optical fingerprint chip 21 does not exceed the side surface of the encapsulation glue layer 25 facing away from the optical fingerprint chip 21, so as to fix the infrared filter 24 on its upper surface. The upper surface of the encapsulation glue layer 25 can be set to be flush with the side surface of the silicon cover plate 23 facing away from the optical fingerprint chip 21.

[0076] When the circuit board 22 is fixed to the second surface of the optical fingerprint chip 21, the packaging glue layer 25 can also seal the interface between the optical fingerprint chip 21 and the circuit board 22 to ensure the sealing of the entire packaging structure.

[0077] Figure 2 In the illustrated manner, the silicon cover plate 23 and the optical fingerprint chip 21 are bonded and fixed by transparent optical glue 27. After the silicon cover plate 23 and the optical fingerprint chip 21 are bonded and fixed by transparent optical glue 27, the through hole 231 is formed. The transparent optical glue 27 in the through hole 231 can be removed after the through hole 231 is formed.

[0078] refer to Figure 4 and Figure 5 , Figure 4 A schematic diagram of another packaging structure of an optical fingerprint chip provided by an embodiment of the present invention, Figure 5 for Figure 4 The schematic diagram of the structure of the optical fingerprint chip in the packaging structure shown is different from the above-mentioned method in that the silicon cover plate 23 completely covers the first surface; the second surface is provided with a back-side interconnection structure, and the optical fingerprint chip 21 is electrically connected to the external circuit through the back-side interconnection structure.

[0079] In this method, the second surface has a through hole 31, which can be formed by a TSV process, and the through hole 31 exposes the pad 212. The second surface film is covered with an insulating layer 32, and the insulating layer covers the side wall of the through hole 31. The surface of the insulating layer 32 is covered with a rewiring layer 33, and the rewiring layer 33 is connected to the pad 212 at the bottom of the through hole 31. The surface of the rewiring layer 33 is covered with a solder resist layer 34, and the solder resist layer 34 has an opening. The portion of the rewiring layer 33 located outside the through hole 31 is connected to a welding end 213. The welding end 213 is connected to the rewiring layer 33 through the opening.

[0080] Figure 4 and Figure 5 In the illustrated embodiment, the infrared filter 24 is bonded and fixed to the first surface; the silicon cover plate 23 is bonded and fixed to a surface of the infrared filter 24 on a side facing away from the optical fingerprint chip 21 .

[0081] Figure 4 and Figure 5 In the manner shown, the infrared filter 24 completely covers the first surface; the infrared filter 24 completely covers the first surface; the periphery of the infrared filter 24 and the periphery of the silicon cover plate 23 are aligned with the periphery of the optical fingerprint chip 21.

[0082] Figure 4 In the illustrated embodiment, the silicon cover plate 23 and the infrared filter 24 are bonded and fixed by transparent optical adhesive. After the silicon cover plate 23 and the infrared filter 24 are bonded and fixed by transparent optical adhesive 27, the through hole 231 is formed. The transparent optical adhesive 27 in the through hole 231 can be removed after the through hole 231 is formed.

[0083] In the packaging structure described in the embodiment of the present invention, the silicon cover plate 23 is fixed to the first surface by a transparent optical adhesive 27. On the one hand, the transparent optical adhesive 27 can be well bonded and fixed, and has good flatness after curing. At the same time, after the through hole 231 is formed, the transparent optical adhesive 27 in the through hole 231 can be removed by plasma treatment to avoid interference with light when there is residual transparent optical adhesive 27 in the through hole 231. In addition, the transparent optical adhesive 27 has good light transmittance. If there is residual transparent optical adhesive 27 in the through hole 231 due to process conditions, its good light transmittance can also make it less interfere with the propagation of light in the through hole.

[0084] It should be noted that, in the embodiment of the present invention, covering may refer to contact covering in the facing direction or non-contact covering with other structural layers in the middle in the facing direction.

[0085] From the above description, it can be seen that in the packaging structure provided by the embodiment of the present invention, a silicon cover plate 23 with a through hole 231 is used as a collimator, and the silicon cover plate 23 is fixed on the optical fingerprint chip 21. The optical fingerprint chip 21 can be used as an alignment reference standard, and there is no need to fix the silicon cover plate 23 with a bracket. The alignment process is simple and the manufacturing cost is reduced.

[0086] Based on the packaging structure described in the above packaging structure embodiment, another embodiment of the present invention further provides a packaging method. The packaging method is as follows: Figure 6-Figure 15 As shown, Figure 6-Figure 15 A schematic diagram of a packaging method according to an embodiment of the present invention is provided. The packaging method is used to manufacture Figure 2 The packaging structure shown in FIG. 1 includes:

[0087] Step S11: Figure 6 and Figure 7 As shown, a wafer 400 is provided.

[0088] The wafer 400 includes a plurality of optical fingerprint chips 21, and there are cutting channels 10 between the optical fingerprint chips 21; the optical fingerprint chip 21 has a first surface and a second surface opposite to each other, and the first surface includes a plurality of photosensitive pixels and pads 212 electrically connected to the photosensitive pixels. Figure 7 for Figure 6 Section view along the P-P' direction.

[0089] Step S12: Figure 8 As shown, a silicon cover plate 23 is bonded and fixed on the wafer 400 , and the silicon cover plate 23 covers the first surface of all the optical fingerprint chips 21 .

[0090] Step S13: Fig. 9 As shown, taking the photosensitive pixels of the optical fingerprint chip 21 as reference positions, a plurality of through holes 231 corresponding to the photosensitive pixels are formed on the silicon cover plate 23.

[0091] For the optical fingerprint chip 21, the first surface includes a photosensitive area and a peripheral area surrounding the photosensitive area, the photosensitive pixels are arranged in the photosensitive area, and the pads are arranged in the peripheral area; the silicon cover plate covers all the optical fingerprint chips.

[0092] In this process, the photosensitive pixels of the optical fingerprint chip 21 are used as reference positions, including directly forming each through hole 231 corresponding to each photosensitive pixel as a reference position, and the photosensitive area 211 can also be used as a reference to determine the position for forming the through hole in the silicon cover plate 23. Since the layout of the photosensitive pixels in the photosensitive area 211 is known, the layout position of the photosensitive pixels can be obtained according to the photosensitive area 211 to facilitate the formation of the through hole 231.

[0093] After the silicon cover plate 23 is attached and fixed on the wafer 400, before the through hole 231 is formed, the packaging method further includes: thinning the side surface of the silicon cover plate 23 away from the wafer 400 and the side surface of the wafer 400 away from the silicon cover plate 23. Due to the limitation of process conditions, the wafer 400 or the silicon cover plate 23 is thinned separately. In order to avoid the problem of fragmentation of the wafer 400 and the silicon cover plate 23, the thickness of the two is still relatively large after thinning. In the embodiment of the present application, since the overall structure thickness is relatively large after the silicon cover plate 23 is attached and fixed on the wafer 400, the wafer 400 and the silicon cover plate 23 can be thinned to a greater extent during the thinning process.

[0094] Step S14: Figure 10-15 As shown, the wafer 400 and the silicon cover plate 23 are cut based on the cutting channel 10 to form a packaging structure of multiple optical fingerprint chips 21. Each packaging structure has an optical fingerprint chip 21.

[0095] In this step, first, Fig.10 As shown, after forming the through hole 231 and before performing the cutting process, the packaging method further includes: etching the silicon cover plate 23 to expose the pad 212. In this process, the silicon cover plate 23 at the position of the cutting channel 10 is removed at the same time.

[0096] In the packaging method described in the embodiment of the present invention, the step of laminating and fixing the silicon cover plate 23 on the wafer 400 includes: laminating and fixing the silicon cover plate 23 and the wafer 400 by using a transparent optical adhesive 27 .

[0097] Then, if Fig.11 As shown, before the cutting process is performed, the packaging method further includes: removing the transparent optical glue 27 in the through hole. The transparent optical glue 27 in the through hole 23 can be removed by plasma treatment, and the transparent optical glue 27 exposed in the peripheral area can be removed at the same time.

[0098] In such Fig.12 As shown, the wafer 400 is cut based on the cutting channel 10 to form a plurality of packaging structures, each of which has an optical fingerprint chip.

[0099] In the above packaging method, if Fig.13 As shown, after the cutting process, the packaging method further includes: attaching and fixing the second surface of the optical fingerprint chip 21 to a circuit board 22, electrically connecting the pad 212 to the circuit board 22 through a conductive wire 26, and the circuit board 22 is used to be electrically connected to an external circuit.

[0100] In the above packaging method, if Fig.14 As shown, after the cutting process is performed, the packaging method further includes: providing a packaging glue layer 25 in the peripheral area, the packaging glue layer 25 covering the wire 26 and the pad 212. The packaging glue layer 25 is in contact with the side of the silicon cover plate 23, and the side surface of the silicon cover plate 23 facing away from the optical fingerprint chip 21 does not exceed the side surface of the packaging glue layer 25 facing away from the optical fingerprint chip 21.

[0101] In the above packaging method, the silicon cover plate 23 is directly bonded and fixed to the surface of the wafer 400; Fig.15 As shown, after the cutting process is performed, the packaging method further includes: attaching and fixing an infrared filter 24 on a surface of the silicon cover plate 23 that is away from the optical fingerprint chip 21 .

[0102] pass Figure 6-Figure 15 As shown, you can make Figure 2 The package structure is shown.

[0103] refer to Figure 16-Figure 24 , Figure 16-Figure 24 A flow chart of another packaging method provided by an embodiment of the present invention, the packaging method is used to manufacture a packaging structure as shown in Figure 4. In this method, after the cutting process, in each of the packaging structures, the silicon cover 23 completely covers the first surface; before the cutting process, the packaging method further includes: forming a back surface interconnection structure on the second surface, and the optical fingerprint chip 21 is electrically connected to the external circuit through the back surface interconnection structure.

[0104] In this method, before fixing the silicon cover plate 23 on the wafer 400, first Fig.16 As shown, it also includes: attaching and fixing an infrared filter 24 on the surface of the wafer 400. The infrared filter 24 covers all the optical fingerprint chips 21. Then, as Fig.17 As shown, the silicon cover plate 23 is bonded and fixed to the surface of the infrared filter 24 on the side away from the wafer 400 by transparent optical adhesive 27. After bonding and fixing the silicon cover plate 23, in this method, the wafer 400 and the silicon cover plate 23 can also be significantly thinned. Fig.18 As shown, a through hole 231 is formed, and then Fig.19 As shown, the transparent optical glue 27 in the through hole 231 is removed. Figure 20-23 As shown, through the TSV process and the rewiring layer process, a backside interconnection structure is formed on the second surface of each optical fingerprint chip 21. The backside interconnection structure is as described in the above embodiment and will not be repeated here. Fig.24 As shown, through the cutting process, multiple Figure 4 The package structure is shown.

[0105] The packaging method described in the embodiment of the present invention can be used to prepare the packaging structure described in the above embodiment, and the manufacturing process is simple, does not require a high-precision alignment process, and has a low manufacturing cost.

[0106] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0107] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A packaging structure of an optical fingerprint chip, characterized in that: The packaging structure comprises: An optical fingerprint chip, the optical fingerprint chip having a first surface and a second surface opposite to each other, the first surface comprising a plurality of photosensitive pixels and pads electrically connected to the photosensitive pixels; the first surface comprising a photosensitive area and a peripheral area surrounding the photosensitive area, the photosensitive pixels being arranged in the photosensitive area, and the pads being arranged in the peripheral area; A silicon cover plate, the silicon cover plate is attached and fixed on the first surface, and the silicon cover plate has a plurality of through holes arranged one by one opposite to the photosensitive pixels; The photosensitive pixels of the optical fingerprint chip are used as reference positions for forming the through holes on the silicon cover. The silicon cover plate covers the photosensitive area and exposes the peripheral area to expose the bonding pad; the bonding pad is electrically connected to an external circuit through a wire; The packaging structure further includes a packaging glue layer covering the peripheral area, the packaging glue layer covering the wire and the pad; the upper surface of the packaging glue layer is flush with a surface of the side of the silicon cover plate away from the optical fingerprint chip; The silicon cover plate is bonded and fixed on the first surface by transparent optical glue; after the silicon cover plate and the optical fingerprint chip are bonded and fixed by transparent optical glue, the through hole is formed, and the transparent optical glue in the through hole is removed by plasma treatment.

2. The packaging structure according to claim 1, characterized in that: Also includes: An infrared filter is arranged on a surface of the silicon cover plate facing away from the optical fingerprint chip; The silicon cover plate is directly attached to and fixed on the first surface.

3. The packaging structure according to claim 1, characterized in that: A circuit board is fixed to the second surface of the optical fingerprint chip, and the circuit board is used to connect to an external circuit; The wire is connected to the circuit board.

4. A packaging method for an optical fingerprint chip as claimed in any one of claims 1 to 3, characterized in that: The packaging method comprises: A wafer is provided, wherein the wafer comprises a plurality of optical fingerprint chips, wherein cutting channels are provided between the optical fingerprint chips; the optical fingerprint chip comprises a first surface and a second surface opposite to each other, wherein the first surface comprises a plurality of photosensitive pixels and pads electrically connected to the photosensitive pixels; A silicon cover plate is fixed on the wafer by means of transparent optical adhesive, wherein the silicon cover plate covers the first surface of all the optical fingerprint chips; Taking the photosensitive pixels of the optical fingerprint chip as reference positions, a plurality of through holes corresponding to the photosensitive pixels are formed on the silicon cover plate; Removing the transparent optical glue in the through hole by plasma treatment; Performing a cutting process based on the cutting channel to cut the wafer and the silicon cover plate to form a packaging structure of multiple optical fingerprint chips; The first surface includes a photosensitive area and a peripheral area surrounding the photosensitive area, the photosensitive pixels are arranged in the photosensitive area, and the pads are arranged in the peripheral area.

5. The packaging method according to claim 4, characterized in that: After the silicon cover is attached and fixed on the wafer and before the through hole is formed, the packaging method further includes: A surface of the silicon cover plate facing away from the wafer and a surface of the wafer facing away from the silicon cover plate are thinned respectively.

6. The packaging method according to claim 4, characterized in that: The silicon cover plate is directly bonded and fixed to the surface of the wafer; After forming the through hole and before performing the cutting process, the packaging method further includes: The silicon cover plate is etched to expose the pad.

7. The packaging method according to claim 6, characterized in that: After the cutting process is performed, the packaging method further includes: An infrared filter is bonded and fixed to the surface of the silicon cover plate on one side facing away from the optical fingerprint chip.

8. The packaging method according to claim 7, characterized in that: After the cutting process is performed, the packaging method further includes: The second surface of the optical fingerprint chip is attached and fixed to a circuit board, the pad is electrically connected to the circuit board through a conductive wire, and the circuit board is used to be electrically connected to an external circuit.

9. The packaging method according to claim 8, characterized in that: After the cutting process is performed, the packaging method further includes: A packaging glue layer is disposed in the peripheral area, and the packaging glue layer covers the wires and the welding pads.

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