Cutting method of W2W wafer level packaging bonding wafer

Abstract

The invention relates to the technical field of semiconductor manufacturing, in particular to a cutting method of a W2W wafer level packaging bonding wafer, which comprises the following steps of: cutting a sealing cap wafer along a first side of each bonding area in a first direction; cutting the sealing cap wafer along the second side of each bonding area in the second direction; cutting the sealing cap wafer along the third side of each bonding area in the first direction; washing the bonded wafer for the first time; cutting the sealing cap wafer along the fourth side of each bonding area in the second direction; and washing the bonded wafer for the second time. In the invention, the scribing waste material obtained by cutting off the redundant part of the sealing cap wafer between the adjacent bonding areas along the second direction before the first washing and the scribing waste material obtained by cutting off the redundant part of the sealing cap wafer between the adjacent bonding areas along the first direction before the second washing are relatively short and small, and can be easily washed and removed; excessive manual intervention is not needed, and the production efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and in particular to a method for cutting a W2W wafer-level packaging bonded wafer. Background Art

[0002] Wafer-level packaging is an advanced semiconductor packaging technology. It is different from the traditional method of dicing and then packaging. It advances the packaging process of semiconductor devices to the wafer manufacturing stage. W2W (Wafer-to-Wafer) is one of the packaging methods of wafer-level packaging. Its packaging process is to complete the bonding of device wafer (Device Wafer) and cap wafer (Cap Wafer) to obtain bonded wafers, and then divide the bonded wafers into independent finished devices. It has the advantages of no dicing operation before bonding and better protection of devices.

[0003] At present, the cutting process of W2W wafer-level packaging bonded wafers is to first cut off the excess part between the adjacent bonding areas along the direction of the cap wafer, clean up the cut dicing waste, and then cut in another direction and clean up the dicing waste for the second time, and finally cut the device wafer; but the dicing waste during the initial cleaning is a long silicon strip, which is difficult to remove directly by flushing or cleaning, and requires multiple manual interventions, resulting in low production efficiency. Summary of the invention

[0004] The present invention provides a method for cutting a W2W wafer-level packaging bonded wafer, which solves the technical problem of low production efficiency of the existing W2W wafer-level packaging bonded wafer cutting method.

[0005] The bonded wafer includes a capping wafer, a device wafer, and a plurality of bonding regions between the capping wafer and the device wafer. The present invention provides a method for cutting a W2W wafer-level package bonded wafer, comprising:

[0006] Cutting the capping wafer in a first direction along a first side of each bonding area;

[0007] In a second direction, cutting the capping wafer along a second side of each bonding area;

[0008] Cutting the capping wafer along the third side of each bonding area in the first direction;

[0009] performing a first rinse on the bonded wafer;

[0010] In the second direction, cutting the capping wafer along the fourth side of each bonding area;

[0011] The bonded wafer is rinsed a second time.

[0012] Optionally, before cutting the capping wafer along the first side of each bonding area in the first direction, the method further comprises:

[0013] A film is applied to the side of the device wafer facing away from the cap wafer.

[0014] Optionally, the flushing direction of the first flushing, the first direction and the vertical direction are on the same plane.

[0015] Optionally, the flushing direction of the second flushing, the second direction and the vertical direction are on the same plane.

[0016] Optionally, after rinsing the bonded wafer for the second time, the method further includes:

[0017] The device wafer is cut.

[0018] Optionally, the film used for the film is a UV film.

[0019] Optionally, the distance between the lowest position of cutting the capping wafer and the bottom of the membrane is greater than the sum of the thickness of the membrane and the thickness of the device wafer, and less than the sum of the thickness of the membrane, the thickness of the device wafer and the thickness of the bonding area.

[0020] Optionally, the cutting is performed using a dicing tool.

[0021] Optionally, the feed speed of the dicing tool is 11 mm / s to 5 mm / s.

[0022] Optionally, the rotation speed of the dicing tool is 28000 r / min to 33000 r / min.

[0023] It can be seen from the above technical solutions that the present invention has the following advantages:

[0024] The present invention provides a method for cutting a W2W wafer-level package bonded wafer, comprising: in a first direction, cutting the capped wafer along the first side of each bonding area; in a second direction, cutting the capped wafer along the second side of each bonding area; in the first direction, cutting the capped wafer along the third side of each bonding area; performing a first rinse on the bonded wafer; in the second direction, cutting the capped wafer along the fourth side of each bonding area; performing a second rinse on the bonded wafer. In the present invention, the slicing waste obtained by cutting off the excess portion of the capped wafer between the adjacent bonding areas along the second direction before the first rinse, and the slicing waste obtained by cutting off the excess portion of the capped wafer between the adjacent bonding areas along the first direction before the second rinse are both relatively short and can be easily rinsed and removed without requiring too much manual intervention, thereby improving production efficiency. In addition, compared with completing all cutting in all directions and then performing unified rinsing, the dicing waste generated before the two rinsings in this embodiment are all short strips and arranged in the same direction. Combined with a specific rinsing direction, the risk of dicing waste accumulation can be reduced and the rinsing effect can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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 some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0026] Figure 1 A schematic diagram of the structure of bonding wafers before step 101 provided in an embodiment of the present invention;

[0027] Figure 2 A schematic diagram of the cutting position in step 101 provided in an embodiment of the present invention;

[0028] Figure 3 A schematic diagram of the structure of the bonded wafer after the cutting is completed in step 101 provided in an embodiment of the present invention;

[0029] Figure 4 A schematic diagram of the cutting position in step 102 provided in an embodiment of the present invention;

[0030] Figure 5 A schematic diagram of the structure of the bonded wafer after the cutting is completed in step 102 provided in an embodiment of the present invention;

[0031] Figure 6 A schematic diagram of the cutting position in step 103 provided in an embodiment of the present invention;

[0032] Figure 7A schematic diagram of the structure of the bonded wafer after the cutting is completed in step 103 provided in an embodiment of the present invention;

[0033] Figure 8 A schematic diagram of the structure of the bonded wafer after the first rinse in step 104 provided in an embodiment of the present invention;

[0034] Fig. 9 A schematic diagram of the cutting position in step 105 provided in an embodiment of the present invention;

[0035] Fig.10 A schematic diagram of the structure of the bonded wafer after the cutting is completed in step 105 provided in an embodiment of the present invention;

[0036] Fig.11 A schematic diagram of the structure of the bonded wafer after the second rinse in step 106 provided in an embodiment of the present invention.

[0037] Figure ID:

[0038] 1-capping wafer; 2-bonding area; 3-device wafer; 4-cutting route. DETAILED DESCRIPTION

[0039] The embodiment of the present invention provides a method for cutting a W2W wafer-level packaging bonded wafer, which is used to solve the technical problem of low production efficiency of the existing W2W wafer-level packaging bonded wafer cutting method.

[0040] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below 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.

[0041] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention; multiple times and multiple refer to a number greater than one. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0042] See also Figures 1 to 10 , a W2W wafer-level packaging bonding wafer cutting method provided by an embodiment of the present invention comprises:

[0043] Step 101, cutting the capping wafer 1 along the first side of each bonding area 2 in the first direction; the specific cutting route 4 can be referred to Figure 2 .

[0044] Step 102, cutting the capping wafer 1 along the second side of each bonding area 2 in the second direction; the specific cutting route 4 can be referred to Figure 4 .

[0045] Step 103: Cut the capping wafer 1 along the third side of each bonding area 2 in the first direction; the specific cutting route 4 can be referred to Figure 6 .

[0046] Step 104 , performing a first rinse on the bonded wafer.

[0047] Step 105: Cut the capping wafer 1 along the fourth side of each bonding area 2 in the second direction; the specific cutting route 4 can be referred to Fig. 9 .

[0048] Step 106: Rinse the bonded wafer a second time.

[0049] It should be noted that, in the present invention, the bonding wafer includes a capping wafer 1, a device wafer 3 and a plurality of bonding regions 2 located between the capping wafer 1 and the device wafer 3; wherein the device wafer 3 refers to a wafer that has been processed through a series of complex semiconductor manufacturing processes (such as photolithography, etching, ion implantation, deposition, etc.), and tiny electronic devices and circuits are formed on its upper surface; the capping wafer 1 refers to the area used to cover and protect the electronic devices and circuits formed on the device wafer 3 during the wafer-level packaging process; the bonding region 2 includes a bonding ring body and an area enclosed in the middle of the bonding ring, and the bonding ring is used to connect and fix the capping wafer 1 and the device wafer 3, and the electronic devices and circuits formed on the upper surface of the device wafer 3 are located in the middle of the bonding ring The enclosed area is used to achieve the packaging effect; each bonding area 2 is a rectangle with four sides, wherein the first side is parallel to the third side, the second side is parallel to the fourth side, and the connection sequence of the first side, the second side, the third side and the fourth side is not specifically limited; a plurality of bonding areas 2 are distributed in the form of a square array; the first direction and the second direction depend on the directions of the sides of the bonding area 2, and the first direction is perpendicular to the second direction; in both step 104 and step 106, a dicing liquid can be used to rinse the bonded wafer. The dicing liquid is a chemical solution used in the wafer dicing and cutting step in the semiconductor manufacturing process, and is mainly used to remove pollutants and waste generated during the cutting process, and contains components such as surfactants and pH adjusters.

[0050] It can be understood that after completing step 103, the portion of the capping wafer 1 that is not connected to the bonding ring between the adjacent bonding areas 2 along the second direction is cut off to form slicing waste; the rinsing direction, the first direction and the vertical direction of the first rinsing are preferably on the same plane, so as to facilitate the rinsing and removal of the slicing waste generated in step 103; after completing step 105, the portion of the capping wafer 1 that is not connected to the bonding ring between the adjacent bonding areas 2 along the first direction is cut off to form slicing waste; the rinsing direction, the second direction and the vertical direction of the second rinsing are preferably on the same plane, so as to facilitate the rinsing and removal of the slicing waste generated in step 105; the rinsing direction of the first rinsing and the second rinsing do not overlap with the vertical direction.

[0051] In this embodiment, steps 101, 102, 103 and 105 all include one or more cuttings, and the number of cuttings is the same as the maximum number of bonding regions 2 arranged in a direction perpendicular to the cutting direction; for example, based on Figures 1 to 9 The orientation or position relationship shown in the figure is that the horizontal direction is taken as the first direction and the vertical direction is taken as the second direction. In step 101, multiple straight line cuts are performed along the lower side of each bonding area 2 in the first direction, and the number of cuts is the same as the maximum number of bonding areas 2 arranged along the second direction (10); in step 102, multiple straight line cuts are performed along the right side of each bonding area 2 in the second direction, and the number of cuts is the same as the maximum number of bonding areas 2 arranged along the first direction (9); and other steps can be deduced in this way.

[0052] The distance between the lowest position of cutting the capping wafer 1 and the bottom of the bonding wafer (the side of the device wafer 3 facing away from the capping wafer 1) should be greater than the thickness of the device wafer 3 and less than the sum of the thickness of the device wafer 3 and the thickness of the bonding area 2; after completing step 106, the cutting method provided by the present invention may also include: step 107, cutting the device wafer 3 to obtain multiple independent finished devices, and the number of finished devices is the same as the number of bonding areas 2.

[0053] Steps 101, 102, 103, 105 and 107 can all be cut using a dicing tool or a laser cutting tool, and the dicing tool is preferably a diamond rotary blade; when a rotary dicing tool is used for cutting, the feed speed is preferably 11 mm / s to 5 mm / s, and the rotation speed is preferably 28000 r / min to 33000 r / min.

[0054] In the present invention, the dicing waste obtained by cutting off the excess portion of the capping wafer 1 between the bonding areas 2 adjacent along the second direction before the first rinse and the dicing waste obtained by cutting off the excess portion of the capping wafer 1 between the bonding areas 2 adjacent along the first direction before the second rinse are both relatively short and can be easily rinsed away without requiring too much manual intervention, thereby improving production efficiency.

[0055] In addition, compared with completing all cutting in all directions and then performing unified rinsing, the dicing waste generated before the two rinsings in this embodiment are all short strips and arranged in the same direction. Combined with a specific rinsing direction, the risk of dicing waste accumulation can be reduced and the rinsing effect can be improved.

[0056] In a preferred embodiment, before step 101, the method further includes:

[0057] Step 201 : applying a film to the side of the device wafer 3 facing away from the cap wafer 1 .

[0058] The film used in this step is preferably a UV film, which will become easy to peel off under ultraviolet light; the film can fix the device wafer 3; in this preferred embodiment, the distance between the lowest position of cutting the capping wafer 1 and the bottom of the film (that is, the side of the film facing away from the device wafer 3) should be greater than the sum of the thickness of the film and the thickness of the device wafer 3, and less than the sum of the thickness of the film, the thickness of the device wafer 3 and the thickness of the bonding area 2; when the device wafer 3 is cut after completing step 106, the distance between the lowest position of the cut and the bottom of the film should be less than or equal to the thickness of the film but the film should not be divided into small pieces, so that the film can remain intact after the device wafer 3 is cut.

[0059] In a specific implementation of this preferred embodiment, the finished device obtained after the bonded wafer is cut is a non-cooled infrared focal plane detector chip, which has an umbrella structure and a readout circuit, can convert infrared radiation signals into electrical signals, and image objects according to different infrared wavelengths. It is widely used in military, aerospace and civilian fields; in this implementation, the film used in step 201 is a UV film with a thickness of 90um to 100um, the thickness of the device wafer 3 is 725±10um, and the distance from the lowest position of the capping wafer 1 cut in steps 101, 102, 103 and 105 to the bottom of the film is greater than 825um and less than 925um.

[0060] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for cutting a W2W wafer-level packaging bonded wafer, characterized in that: The bonded wafer comprises a capping wafer, a device wafer and a plurality of bonding regions between the capping wafer and the device wafer; the cutting method comprises: Cutting the capping wafer in a first direction along a first side of each bonding area; In a second direction, cutting the capping wafer along a second side of each bonding area; Cutting the capping wafer along the third side of each bonding area in the first direction; performing a first rinse on the bonded wafer; In the second direction, cutting the capping wafer along the fourth side of each bonding area; The bonded wafer is rinsed a second time.

2. The cutting method according to claim 1, characterized in that: Before cutting the capping wafer along the first side of each bonding area in the first direction, the method further comprises: A film is applied to the side of the device wafer facing away from the cap wafer.

3. The cutting method according to claim 1, characterized in that: The flushing direction of the first flushing, the first direction and the vertical direction are on the same plane.

4. The cutting method according to claim 1, characterized in that: The flushing direction of the second flushing, the second direction and the vertical direction are on the same plane.

5. The cutting method according to claim 1, characterized in that: After the bonding wafer is rinsed for the second time, the method further includes: The device wafer is cut.

6. The cutting method according to claim 2, characterized in that: The film used in the film is a UV film.

7. The cutting method according to claim 6, characterized in that: The distance from the lowest position of cutting the capping wafer to the bottom of the film is greater than the sum of the thickness of the film and the thickness of the device wafer, and less than the sum of the thickness of the film, the thickness of the device wafer and the thickness of the bonding area.

8. The cutting method according to claim 1, characterized in that: The cutting is performed using a dicing tool.

9. The cutting method according to claim 8, characterized in that: The feed speed of the dicing tool is 11 mm / s to 5 mm / s.

10. The cutting method according to claim 8, characterized in that: The rotation speed of the dicing tool is 28000r / min to 33000r / min.

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