Optical sensor based on wafer-level chip scale packaging and packaging method thereof
By making pad bumps and cofferdams on optical sensor wafers and packaging them using metal lines on glass covers, the limitations of existing optical sensor WLCSP packaging methods are solved, achieving wider packaging applicability.
Patent Information
- Application Number
- CN202411903082.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-23
- Publication Date
- 2025-03-21
AI Technical Summary
The existing optical sensor WLCSP packaging method can only be used when there is no functional area or line below the wafer pad. If there is a functional area or line, it cannot be packaged.
Wafer pad bumps and cofferdams are made on the optical sensor wafer, the optical sensor wafer is divided into a single chip, and a glass cover with grooves is provided on which metal lines and shell pad bumps are formed, the shell pad bumps are bonded to the wafer pad bumps, and the metal lines on the glass cover are electrically connected to the substrate.
It realizes that WLCSP packaging can be performed regardless of whether there are functional areas and lines under the wafer pad, solving the problem of strong limitations of existing packaging methods.
Smart Images
Figure CN119677246A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor process technology, and in particular to an optical sensor based on wafer-level chip scale packaging and a packaging method thereof. Background Art
[0002] Optical sensors are sensors that measure based on optical principles. They are widely used because of their non-contact and non-destructive measurement, almost interference-free, high-speed transmission, and telemetry and remote control capabilities. In order to reduce the size of optical sensors and improve their performance, optical sensors are currently packaged using wafer-level chip scale packaging processes.
[0003] Based on Wafer Level Chip Scale Packaging (WLCSP), packaging and testing are first performed on the entire wafer, and then cut into individual chip particles, thereby effectively reducing the packaging volume.
[0004] In the existing WLCSP packaging process for optical sensors, a cofferdam is generally made on the glass by photolithography first, and then the glass and the wafer are bonded by adhesive; the pads on the wafer are connected to the back of the wafer by opening a through hole on the back of the wafer, and the pad signal is led to the back of the wafer using a redistribution layer and electroplating process. However, the existing WLCSP packaging process for optical sensors can only be used when there is no functional area or circuit under the wafer pad. If there is a functional area or circuit under the wafer pad, the WLCSP packaging process cannot be used to package the optical sensor. Summary of the invention
[0005] The object of the present invention is to provide an optical sensor based on wafer level chip scale packaging and a packaging method thereof, so as to at least solve the problem that the existing optical sensor WLCSP packaging method has strong limitations.
[0006] In order to solve the above technical problems, the present invention provides a packaging method of an optical sensor based on wafer-level chip scale packaging, comprising: Fabricating wafer pad bumps and dams on optical sensor wafers; Slicing the optical sensor wafer into individual optical sensor chips; Providing a glass cover shell, wherein the glass cover shell has a groove; forming metal circuits and cover pad bumps on the glass cover; Bonding the cover pad bumps to the wafer pad bumps to connect and fix the optical sensor chip to the glass cover to obtain a basic semi-finished product; providing a substrate; The base semi-finished product is electrically connected and fixed to the substrate by using the metal circuit formed on the glass cover to obtain a packaged semi-finished product; The hollow area of the packaged semi-finished product is filled to obtain a packaged optical sensor.
[0007] Optionally, in the packaging method of the optical sensor based on wafer-level chip scale packaging, the method of making wafer pad bumps and cofferdams on the optical sensor wafer includes: Fabricating wafer pad bumps on an optical sensor wafer; A dam is created between the wafer pad bumps and the photosensitive area of the optical sensor wafer.
[0008] Optionally, in the packaging method of the optical sensor based on wafer-level chip scale packaging, the method of making wafer pad bumps and cofferdams on the optical sensor wafer further includes: The optical sensor wafer is ground to a thickness of 200~278μm.
[0009] Optionally, in the packaging method of the optical sensor based on wafer-level chip scale packaging, the height of the wafer pad bump is 54-64 μm; and the height of the cofferdam is 55-65 μm.
[0010] Optionally, in the packaging method of the optical sensor based on wafer-level chip scale packaging, the method of providing a glass cover shell includes: Provide glass; A groove is formed on the lower surface of the glass by using photolithography and etching processes, wherein the size of the groove is 20-40 μm larger than the size of the optical sensor chip, and the depth of the groove is 100-150 μm.
[0011] Optionally, in the packaging method of the optical sensor based on wafer-level chip scale packaging, the method of forming metal circuits and cover pad bumps on the glass cover includes: In the groove of the glass cover shell, the cover shell pad bump is formed by exposure, development and electroplating; A through hole is drilled on a side of the glass cover away from the groove at a position corresponding to the cover cover pad bump, and the inner wall of the through hole is electroplated to electrically connect the cover cover pad bump with the through hole; A metal redistribution layer is formed on a side of the glass cover away from the groove by photolithography and electroplating; A through hole is drilled on a side of the glass cover away from the groove, corresponding to the side wall of the groove, and the inner wall of the through hole is electroplated; A solder ball is implanted on the surface of the through hole on the side wall of the groove, and the solder ball is electrically connected to the metal redistribution layer through the through hole to form a metal circuit.
[0012] Optionally, in the packaging method of the optical sensor based on wafer-level chip scale packaging, the position of the cover pad bump corresponds to the position of the wafer pad bump on the optical sensor chip.
[0013] Optionally, in the packaging method of the optical sensor based on wafer-level chip scale packaging, the method of obtaining the packaged semi-finished product by electrically connecting and fixing the base semi-finished product to the substrate using the metal circuit formed on the glass cover comprises: The solder balls are soldered to the substrate pads on the substrate by using a reflow soldering process to obtain a semi-finished package product.
[0014] Optionally, in the packaging method of the optical sensor based on wafer-level chip scale packaging, the method of filling the hollow area of the packaged semi-finished product to obtain the packaged optical sensor includes: The hollow area between the glass cover and the substrate is filled with epoxy glue.
[0015] In order to solve the above technical problems, the present invention further provides an optical sensor, which is packaged by using the packaging method of an optical sensor based on wafer-level chip scale packaging as described in any one of the above items, wherein the optical sensor comprises a substrate, an optical sensor chip and a glass cover shell which are arranged in sequence from bottom to top; the glass cover shell has a groove, and the optical sensor chip is located in the groove; The substrate has a substrate pad, the optical sensor chip has a wafer pad bump, a metal circuit and a cover pad bump are formed on the glass cover, the substrate pad is welded to the metal circuit, and the wafer pad bump is bonded to the cover pad bump.
[0016] Optionally, in the optical sensor, the optical sensor chip further has a cofferdam, and the cofferdam is located between the wafer pad bump and the photosensitive area of the optical sensor wafer; and epoxy glue is filled between the substrate and the glass cover.
[0017] Optionally, in the optical sensor, the height of the wafer pad bump is 54-64 μm; the height of the cofferdam is 55-65 μm; the size of the groove of the glass cover is 20-40 μm larger than the size of the optical sensor chip, and the depth of the groove is 100-150 μm.
[0018] The optical sensor based on wafer-level chip scale packaging and the packaging method thereof provided by the present invention include: making wafer pad bumps and cofferdams on an optical sensor wafer; dividing the optical sensor wafer into single optical sensor chips; providing a glass cover shell, wherein the glass cover shell has a groove; forming a metal circuit and a cover shell pad bump on the glass cover shell; bonding the cover shell pad bump with the wafer pad bump to connect and fix the optical sensor chip to the glass cover shell to obtain a basic semi-finished product; providing a substrate; using the metal circuit formed on the glass cover shell to electrically connect and fix the basic semi-finished product to the substrate to obtain a packaged semi-finished product; filling the hollow area of the packaged semi-finished product to obtain a packaged optical sensor. By forming metal circuits and cover pad bumps on the glass cover, connecting the wafer pad bumps with the cover pad bumps, and electrically connecting the substrate with the metal circuits, the optical sensor signal is transmitted to the substrate through the metal circuits on the glass cover without opening a hole on the back of the wafer. Therefore, WLCSP packaging can be performed regardless of whether there are functional areas and circuits under the wafer pads, which solves the problem that the existing optical sensor WLCSP packaging method has strong limitations. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 A flow chart of a packaging method for an optical sensor based on wafer-level chip scale packaging provided in this embodiment; 2(A) to 2(M) are schematic cross-sectional views of the structure of the optical sensor corresponding to each step in the packaging method of the optical sensor based on wafer-level chip scale packaging provided by this embodiment; The descriptions of the reference numerals are as follows: 100-optical sensor wafer; 101-wafer pad bump; 102-dam; 103-photosensitive area; 110-optical sensor chip; 200-glass cover; 201-groove; 210-cover pad bump; 220-through hole; 230-metal redistribution layer; 240-soldering ball; 300-substrate; 310-substrate pad; 400-Epoxy glue. DETAILED DESCRIPTION
[0020] The optical sensor based on wafer-level chip scale packaging and the packaging method thereof proposed by the present invention are further described in detail below in combination with the accompanying drawings and specific embodiments. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In addition, the structure shown in the accompanying drawings is often a part of the actual structure. In particular, the emphasis that each drawing needs to show is different, and sometimes different proportions are used.
[0021] It should be noted that the terms "first", "second", etc. in the specification, claims and drawings of the present invention are used to distinguish similar objects in order to describe the embodiments of the present invention, rather than to describe a specific order or sequence. It should be understood that the structures used in this way can be interchanged under appropriate circumstances. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.
[0022] This embodiment provides a packaging method for an optical sensor based on wafer-level chip scale packaging, such as Figure 1 As shown, including: S1, fabricating wafer pad bumps and dams on the optical sensor wafer; S2, dividing the optical sensor wafer into individual optical sensor chips; S3, providing a glass cover shell, wherein the glass cover shell has a groove; S4, forming metal circuits and cover pad bumps on the glass cover; S5, bonding the cover pad bumps to the wafer pad bumps to connect and fix the optical sensor chip to the glass cover to obtain a basic semi-finished product; S6, providing a substrate; S7, using the metal circuit formed on the glass cover, electrically connecting and fixing the base semi-finished product to the substrate to obtain a packaged semi-finished product; S8, filling the hollow area of the packaged semi-finished product to obtain a packaged optical sensor.
[0023] The packaging method of an optical sensor based on wafer-level chip scale packaging provided in this embodiment forms metal circuits and cover pad bumps on a glass cover, connects the wafer pad bumps with the cover pad bumps, and electrically connects the substrate with the metal circuits, so that the optical sensor signal is transmitted to the substrate through the metal circuits on the glass cover without opening a hole on the back of the wafer to lead out. Therefore, WLCSP packaging can be performed regardless of whether there are functional areas and circuits under the wafer pads, thereby solving the problem that the existing optical sensor WLCSP packaging method has strong limitations.
[0024] It should be noted that, in actual application, step S3 and step S4 can be performed before step S1 or step S2, or can be performed simultaneously with step S1 or step S2, that is, the implementation of step S3 and step S4 is independent of step S1 and step S2. The replacement of the order of steps without violating the purpose of this application should also fall within the scope of protection of this application.
[0025] Specifically, in this embodiment, step S1, a method for manufacturing wafer pad bumps and cofferdams on an optical sensor wafer includes: S11 , as shown in FIG. 2 (A) , wafer bonding pad bumps 101 are fabricated on the optical sensor wafer 100 .
[0026] A plurality of optical sensor chips are formed on the optical sensor wafer 100 , and each optical sensor chip should have a wafer pad bump 101 to lead out an optical sensor signal.
[0027] The method of forming the wafer pad bump 101 is well known to those skilled in the art and will not be described in detail in this application.
[0028] In a specific embodiment, the height of the wafer pad bump 101 is 54-64 μm to ensure that it can be effectively bonded with the cover pad bump on the glass cover later.
[0029] S12 , as shown in FIG. 2(B) , a dam 102 is formed between the wafer pad bump 101 and the photosensitive region 103 of the optical sensor wafer 100 .
[0030] Among them, multiple optical sensor chips are formed on the optical sensor wafer 100, and a cofferdam 102 should be made between the photosensitive area 103 on each optical sensor chip and the wafer pad bump 101 to ensure that the cofferdam 102 is against the glass cover during subsequent packaging, so that the photosensitive area 103 of the optical sensor chip is sealed.
[0031] The method of forming the cofferdam 102 is also well known to those skilled in the art and will not be described in detail in this application.
[0032] In a specific embodiment, the height of the dam 102 is 55-65 μm, so as to ensure that the dam 102 can effectively abut against the glass cover to seal the photosensitive area 103 while the wafer pad bump 101 is effectively bonded to the cover pad bump on the glass cover.
[0033] In practical applications, the height of the wafer pad bump 101 and the height of the cofferdam 102 need to be determined by comprehensive consideration.
[0034] Preferably, in order to ensure reliable connection between the subsequent glass cover and the substrate, in this embodiment, step S1 further includes: grinding the optical sensor wafer 100 to a thickness of 200-278 μm. In this way, the height of the optical sensor wafer 100 can be matched with the depth of the groove after the glass cover and the substrate are connected.
[0035] Furthermore, in this embodiment, in step S2 , as shown in FIG. 2 (C ), the optical sensor wafer 100 is divided into individual optical sensor chips 110 .
[0036] In practical applications, a cutter wheel saw may be used to separate the optical sensor wafer 100 into individual optical sensor chips 110 .
[0037] Furthermore, in this embodiment, step S3, the method of providing a glass cover comprises: S31, providing glass.
[0038] Specifically, considering that metal lines and through holes need to be formed by photolithography and etching processes, white glass can be selected. When coated glass is selected, the coating of the coated glass can be single-sided, that is, the side used for photolithography is not coated, so as to ensure that the coating will not be peeled off due to photolithography.
[0039] S32 , as shown in FIG. 2 (D), a groove 201 is formed on the lower surface of the glass by using photolithography and etching processes to obtain a glass cover 200 .
[0040] Specifically, taking into account the deviation accuracy of the assembly process, in order to ensure that the subsequent optical sensor chip 110 can be reliably placed in the groove 201 and does not collide with other parts of the glass cover 200, in this embodiment, the size of the groove 201 is 20-40 μm larger than the size of the optical sensor chip 110, and the depth of the groove 201 is 100-150 μm.
[0041] It should be noted that the “size” mentioned in the present application should be understood as length and width, that is, the length and width of the groove 201 are 20-40 μm larger than the length and width of the optical sensor chip 110 .
[0042] Furthermore, in this embodiment, step S4, the method of forming metal circuits and cover pad bumps on the glass cover includes: S41 , as shown in FIG. 2(E) , a cover pad bump 210 is formed in the groove 201 of the glass cover 200 by exposure, development, and electroplating.
[0043] The position of the formed cover pad bump 210 should correspond to the position of the wafer pad bump 101 on the optical sensor chip 110 to facilitate the bonding of the two later.
[0044] For the convenience of explanation, in this embodiment, the side of the glass cover 200 having the groove 201 is marked as side A, and the side away from the groove 201 is marked as side B.
[0045] S42 , as shown in FIG. 2 (F), a through hole 220 is drilled on one side (side B) of the glass cover 200 away from the groove 201 , corresponding to the cover pad bump 210 , and the inner wall of the through hole 220 is electroplated to electrically connect the cover pad bump 210 with the through hole 220 .
[0046] Specifically, a region corresponding to the cover pad bump 210 can be reserved on the B surface of the glass cover shell 200 by using photoresist, that is, a region of the vertical projection of the cover pad bump 210 on the B surface of the glass cover shell 200; then, a through hole 220 is formed in the glass cover shell 200 at the region corresponding to the cover pad bump 210 by using a photolithography process; then, a metal layer is electroplated on the inner wall of the through hole 220 by using an electroplating process, or metal is filled in the through hole 220, so as to lead the cover pad bump 210 to the B surface of the glass cover shell 200.
[0047] S43 , as shown in FIG. 2(G) , a metal redistribution layer 230 is formed on a side (side B) of the glass cover 200 away from the groove 200 by photolithography and electroplating.
[0048] Specifically, a redistribution layer area can be reserved on the B side of the glass cover 200 by using a photolithography process. The area should pass through the through hole 220 formed in step S42. Then, electroplating is performed in the routing groove of the redistribution layer area by using an electroplating process to form a metal redistribution layer 230.
[0049] S44 , as shown in FIG. 2 (H ), a through hole 220 is drilled on a side (side B) of the glass cover 200 away from the groove 201 , corresponding to the side wall of the groove 201 , and the inner wall of the through hole 220 is electroplated.
[0050] This step is similar to step S42 , except that the through hole 220 formed in this step is located on the side wall of the groove 201 , that is, the end of the through hole 220 is located in the area where the outer periphery of the glass cover 200 contacts the substrate.
[0051] S45 , as shown in FIG. 2 (I), solder balls 240 are implanted on the surface of the through holes 220 on the sidewalls of the grooves 201 . The solder balls 240 are electrically connected to the metal redistribution layer 230 through the through holes 220 to form metal circuits.
[0052] At this point, the electrical connection between the cover pad bumps 210 and the solder balls 240 is completed on the glass cover 200 .
[0053] Furthermore, in this embodiment, in step S5 , as shown in FIG. 2 (J), the cover pad bumps 210 are bonded to the wafer pad bumps 101 to connect and fix the optical sensor chip 110 to the glass cover 200 , thereby obtaining a basic semi-finished product.
[0054] The bonding method is well known to those skilled in the art, and will not be described in detail in this application. After the cover pad bump 210 is bonded to the wafer pad bump 101, the electrical connection of the wafer pad bump 101, the cover pad bump 210, the metal line and the solder ball 240 is completed. At the same time, the top of the cofferdam 102 should be in close contact with the glass cover 200 to seal the photosensitive area 103.
[0055] Furthermore, in this embodiment, in step S6 , a substrate 300 is provided. As shown in FIG. 2(K) , the substrate 300 has a substrate pad 310 , so as to facilitate soldering the solder ball 240 to the substrate pad 310 , thereby realizing signal transmission of the optical sensor chip 110 .
[0056] Furthermore, in this embodiment, in step S7, the method of electrically connecting and fixing the basic semi-finished product with the substrate 300 by using the metal circuit 230 formed on the glass cover shell 200 to obtain the packaged semi-finished product includes: as shown in FIG. 2 (L), using a reflow process to weld the welding ball 240 to the substrate pad 310 on the substrate 300 to obtain the packaged semi-finished product.
[0057] In this way, the electrical connection among the wafer pad bumps 101 , the cover pad bumps 210 , the metal lines, the solder balls 240 and the substrate pads 310 is completed, so that the substrate 300 can receive the signal of the optical sensor chip 110 .
[0058] Furthermore, in this embodiment, step S8 , the method of filling the hollow area of the semi-finished package to obtain a packaged optical sensor includes: as shown in FIG. 2 (M), using epoxy glue 400 to fill the hollow area between the glass cover 200 and the substrate 300 .
[0059] In this way, the epoxy glue 400 is used to fill the space between the glass cover 200 and the substrate 300 tightly, thereby ensuring the reliability and stability of the connection between the various components in the packaged optical sensor. At the same time, thanks to the presence of the cofferdam 102, the photosensitive area 103 of the optical sensor chip 110 will not be filled with the epoxy glue 400, thereby ensuring that it can normally receive light through the glass cover 200.
[0060] Corresponding to the packaging method provided in this embodiment, this embodiment also provides an optical sensor, which is packaged using the packaging method of the optical sensor as described above, as shown in FIG2 (M), the optical sensor includes a substrate 300, an optical sensor chip 110 and a glass cover shell 200 arranged in sequence from bottom to top; the glass cover 200 shell has a groove 201, and the optical sensor chip 110 is located in the groove 201.
[0061] The substrate 300 has a substrate pad 310 , the optical sensor chip 110 has a wafer pad bump 101 , a metal circuit and a cover pad bump 210 are formed on the glass cover 200 , the substrate pad 310 is welded to the metal circuit, and the wafer pad bump 101 is bonded to the cover pad bump 210 .
[0062] Furthermore, in this embodiment, the optical sensor chip 110 further has a dam 102 , and the dam 102 is located between the wafer pad bump 101 and the photosensitive area 103 of the optical sensor wafer; and epoxy glue 400 is filled between the substrate 300 and the glass cover 200 .
[0063] According to the above packaging method, in this embodiment, the height of the wafer pad bump 101 in the manufactured optical sensor is 54-64 μm; the height of the cofferdam 102 is 55-65 μm; the size of the groove 201 of the glass cover 200 is 20-40 μm larger than the size of the optical sensor chip 110, and the depth of the groove 201 is 100-150 μm.
[0064] In this way, taking into account the packaging process deviation, not only can the reliability of bonding between the wafer pad bump 101 and the cover pad bump 210 be guaranteed, but also the sealing of the cofferdam 102 to the photosensitive area 103 of the optical sensor wafer can be guaranteed, and at the same time, structural interference between the optical sensor chip 110 and the glass cover 200 and the substrate 300 can be avoided.
[0065] The optical sensor based on wafer-level chip scale packaging and the packaging method thereof provided by the present invention do not require through-hole leads on the back side of the wafer during the entire process, but instead realize electrical connection between the optical sensor chip and the substrate by forming metal traces on the glass cover. Therefore, regardless of whether there are functional areas or circuits on the back side of the wafer, the packaging method for the optical sensor based on wafer-level chip scale packaging provided by this embodiment can be used to package the optical sensor, thereby solving the problem that the existing optical sensor WLCSP packaging method has strong limitations.
[0066] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other. In addition, the different parts between the various embodiments can also be used in combination with each other, and the present invention is not limited to this.
[0067] The optical sensor based on wafer-level chip scale packaging and the packaging method thereof provided by the present invention include: making wafer pad bumps and cofferdams on an optical sensor wafer; dividing the optical sensor wafer into single optical sensor chips; providing a glass cover shell, wherein the glass cover shell has a groove; forming a metal circuit and a cover shell pad bump on the glass cover shell; bonding the cover shell pad bump with the wafer pad bump to connect and fix the optical sensor chip to the glass cover shell to obtain a basic semi-finished product; providing a substrate; using the metal circuit formed on the glass cover shell to electrically connect and fix the basic semi-finished product to the substrate to obtain a packaged semi-finished product; filling the hollow area of the packaged semi-finished product to obtain a packaged optical sensor. By forming metal circuits and cover pad bumps on the glass cover, connecting the wafer pad bumps with the cover pad bumps, and electrically connecting the substrate with the metal circuits, the optical sensor signal is transmitted to the substrate through the metal circuits on the glass cover without opening a hole on the back of the wafer. Therefore, WLCSP packaging can be performed regardless of whether there are functional areas and circuits under the wafer pads, which solves the problem that the existing optical sensor WLCSP packaging method has strong limitations.
[0068] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.
Claims
1. A packaging method for an optical sensor based on wafer-level chip scale packaging, characterized in that: include: Fabricating wafer pad bumps and dams on optical sensor wafers; Slicing the optical sensor wafer into individual optical sensor chips; Providing a glass cover shell, wherein the glass cover shell has a groove; forming metal circuits and cover pad bumps on the glass cover; Bonding the cover pad bumps to the wafer pad bumps to connect and fix the optical sensor chip to the glass cover to obtain a basic semi-finished product; providing a substrate; The base semi-finished product is electrically connected and fixed to the substrate by using the metal circuit formed on the glass cover to obtain a packaged semi-finished product; The hollow area of the packaged semi-finished product is filled to obtain a packaged optical sensor.
2. The packaging method of an optical sensor based on wafer-level chip scale packaging according to claim 1, characterized in that: The method for making wafer pad bumps and cofferdams on an optical sensor wafer comprises: Fabricating wafer pad bumps on an optical sensor wafer; A dam is created between the wafer pad bumps and the photosensitive area of the optical sensor wafer.
3. The packaging method of an optical sensor based on wafer-level chip scale packaging according to claim 2, characterized in that: The method of making wafer pad bumps and cofferdams on an optical sensor wafer also includes: The optical sensor wafer is ground to a thickness of 200~278μm.
4. The packaging method of an optical sensor based on wafer-level chip scale packaging according to claim 1, characterized in that: The height of the wafer pad bump is 54-64 μm; the height of the cofferdam is 55-65 μm.
5. The packaging method of an optical sensor based on wafer-level chip scale packaging according to claim 1, characterized in that: The method for providing a glass cover comprises: Provide glass; A groove is formed on the lower surface of the glass by using photolithography and etching processes, wherein the size of the groove is 20-40 μm larger than the size of the optical sensor chip, and the depth of the groove is 100-150 μm.
6. The packaging method of an optical sensor based on wafer-level chip scale packaging according to claim 1, characterized in that: The method for forming metal circuits and cover pad bumps on a glass cover comprises: In the groove of the glass cover shell, the cover shell pad bump is formed by exposure, development and electroplating; A through hole is drilled on a side of the glass cover away from the groove at a position corresponding to the cover cover pad bump, and the inner wall of the through hole is electroplated to electrically connect the cover cover pad bump with the through hole; A metal redistribution layer is formed on a side of the glass cover away from the groove by photolithography and electroplating; A through hole is drilled on a side of the glass cover away from the groove, corresponding to the side wall of the groove, and the inner wall of the through hole is electroplated; A solder ball is implanted on the surface of the through hole on the side wall of the groove, and the solder ball is electrically connected to the metal redistribution layer through the through hole to form a metal circuit.
7. The packaging method of an optical sensor based on wafer-level chip scale packaging according to claim 1, characterized in that: The positions of the cover pad bumps correspond to the positions of the wafer pad bumps on the optical sensor chip.
8. The packaging method of an optical sensor based on wafer-level chip scale packaging according to claim 6, characterized in that: The method of obtaining a packaged semi-finished product by electrically connecting and fixing the base semi-finished product to the substrate using the metal circuit formed on the glass cover shell comprises: The solder balls are soldered to the substrate pads on the substrate by using a reflow soldering process to obtain a semi-finished package product.
9. The packaging method of an optical sensor based on wafer-level chip scale packaging according to claim 1, characterized in that: The method of filling the hollow area of the packaged semi-finished product to obtain a packaged optical sensor comprises: The hollow area between the glass cover and the substrate is filled with epoxy glue.
10. An optical sensor, packaged by the packaging method of an optical sensor based on wafer-level chip scale packaging according to any one of claims 1 to 9, characterized in that: The optical sensor comprises a substrate, an optical sensor chip and a glass cover which are arranged in sequence from bottom to top; the glass cover has a groove, and the optical sensor chip is located in the groove; The substrate has a substrate pad, the optical sensor chip has a wafer pad bump, a metal circuit and a cover pad bump are formed on the glass cover, the substrate pad is welded to the metal circuit, and the wafer pad bump is bonded to the cover pad bump.
11. The optical sensor according to claim 10, characterized in that The optical sensor chip also has a cofferdam, which is located between the wafer pad bump and the photosensitive area of the optical sensor wafer; epoxy glue is filled between the substrate and the glass cover.
12. The optical sensor according to claim 11, characterized in that The height of the wafer pad bump is 54-64 μm; the height of the cofferdam is 55-65 μm; the size of the groove of the glass cover is 20-40 μm larger than the size of the optical sensor chip, and the depth of the groove is 100-150 μm.