Wafer cutting method and wafer structure to be cut

Abstract

The invention discloses a wafer cutting method and a to-be-cut structure of a wafer, and belongs to the field of semiconductors, the wafer cutting method comprises the following steps: a base film is provided, the base film is provided with raised lines protruding out of the upper surface of the base film, and the positions of the raised lines correspond to cutting channels of the wafer; a wafer, an FOW film and adhesive are provided, the adhesive covers the upper surfaces of the base film and the protruding strips, the FOW film is arranged on the lower surface of the wafer, and the FOW film is connected with the adhesive; the wafer is cut according to a preset wafer cutting channel, the wafer is cut into a plurality of chips, and the bottom wall of the cutting channel is located between the upper surface of the base film and the upper surfaces of the protruding strips; and separating the FOW film from the adhesive to obtain a plurality of units. According to the invention, the raised lines are arranged on the base film, so that the two adjacent units are blocked by the raised lines after cutting, the FOW film can be effectively prevented from flowing under the influence of the gravity of a chip, and the FOW film can be effectively prevented from being adhered.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors, and in particular to a wafer cutting method and a wafer structure to be cut. Background Art

[0002] like Figure 1 As shown, the existing wafer 1 is cut by combining the FOW film 2 with the base film 4. The thickness of the currently produced FOW film 2 is about 60um. When the width of the cutting channel 5 of the wafer is about 80μm, the structure after cutting is as follows Figure 2 As shown in FIG. 1 , when the width of the cutting channel 5 of the wafer becomes narrower, it is found that after cutting, the FOW film 2 flows under the influence of gravity, and the FOW films 2 of adjacent units on the base film flow along the surface of the base film, causing adhesion problems, as shown in FIG. Figure 3 . Summary of the invention

[0003] In view of the above problems, the present invention proposes a wafer cutting method and a wafer to-be-cut structure, so that the FOW film will not flow and stick together after cutting.

[0004] The technical solution adopted by the present invention is as follows: A wafer cutting method comprises the following steps: Providing a base film, wherein the base film has a convex strip protruding from the upper surface of the base film, and the position of the convex strip corresponds to a cutting channel of a wafer to be cut subsequently; Providing a wafer, a FOW film and an adhesive, wherein the adhesive covers the upper surface of the base film and the convex strips, the FOW film is disposed on the lower surface of the wafer, and the FOW film is connected to the adhesive; Cutting the wafer according to a preset wafer cutting channel to cut the wafer into a plurality of chips, wherein the bottom wall of the cutting channel is at least located below the upper surface of the adhesive, and the cutting channel does not cut through the base film; The FOW film is separated from the adhesive to obtain a plurality of units, wherein the units include a chip and the FOW film located on the lower surface of the chip.

[0005] The present application provides convex strips on the base film so that there are convex strips between two adjacent units after cutting to block them, which can effectively prevent the FOW film from flowing due to the gravity of the chip and effectively prevent the FOW film from sticking.

[0006] In one embodiment of the present invention, the bonding force between the adhesive and the FOW film is smaller than the bonding force between the FOW film and the wafer.

[0007] This arrangement facilitates the separation of the units and prevents the chip from being separated from the FOW film when the FOW film and the adhesive are separated.

[0008] In one embodiment of the present invention, the convex strips are arranged in a crisscross pattern.

[0009] In one embodiment of the present invention, the material of the convex strips is the same as that of the base film.

[0010] In one embodiment of the present invention, the material of the convex strip and the base film are different, and the convex strip is fixed on the upper end surface of the base film.

[0011] There are many ways to form convex stripes on the base film. For example, a glue coating mechanism is used to directly apply a criss-cross glue on the base film as required, and the convex stripes are formed after the glue is cured.

[0012] For another example, a mold may be designed to form convex strips on the base film.

[0013] In one embodiment of the present invention, the convex strips are processed by a first mold, and the first mold includes: A base plate having downwardly disposed extension columns; The rectangular pressing plates are fixed below the extension columns. The lower surfaces of the rectangular pressing plates are on the same horizontal plane, and the gaps between the rectangular pressing plates form crisscross limiting channels.

[0014] During the specific operation, the base film is placed directly below the first mold. When working, the first mold is pressed downward, and the rectangular pressure plate contacts and cooperates with the base film; then the convex strip coated with bonding glue at the bottom can be placed on the limiting channel, or the glue liquid is coated on the limiting channel, and the convex strip is formed after the glue liquid is cured.

[0015] The rectangular pressing plates are connected via extension columns, and the extension columns are parallel to each other, so that a larger operating space can be formed to place the convex strips or the gluing mechanism for gluing.

[0016] In one embodiment of the present invention, the convex strips are processed by a second mold, the second mold is a plate-like structure, the lower surface of the second mold has liquid injection grooves arranged in a criss-cross pattern, the upper surface of the base has at least one liquid injection port and at least one exhaust port, and both the liquid injection port and the exhaust port are connected to the liquid injection grooves.

[0017] During the specific operation, the second mold is placed on the upper surface of the base film so that the periphery of the second mold is in sealing contact with the base film, and glue is injected into the injection port through an injection gun. The air in the injection groove is discharged through a suction gun connected to the exhaust port to facilitate better and faster injection of the glue into the injection groove. After completion, the glue is cured to form convex strips.

[0018] In one embodiment of the present invention, the upper surface of the base film has a plurality of first strip grooves arranged in parallel and a plurality of second strip grooves arranged in parallel, and the first strip grooves are perpendicular to the second strip grooves. In this case, the convex strips can be a separate film, and the convex strips can be directly embedded in the first strip grooves and the second strip grooves. Because of the limiting effect of the strip grooves, the convex strips are not easy to move after being embedded. In addition to directly embedding the first strip grooves and the second strip grooves, the convex strips can also be embedded in the first strip grooves and the second strip grooves after being coated with glue, so that the convex strips can be better combined and fixed with the base film after installation. In addition to being a separate film, the convex strips can also be formed by glue, and the glue is injected into the first strip grooves and the second strip grooves by a glue injection mechanism, and the upper end of the glue is exposed on the upper surface of the base film. After the glue is solidified, the convex strips are formed.

[0019] In actual use, the first strip groove and the second strip groove of the base film can be formed when the base film is processed, or can be formed separately after the base film is processed, such as by pressing a mold.

[0020] In actual use, preferably, in order to ensure the structural strength of the base film, the base film is thickened compared to the thickness of the traditional process, that is, it is a thickened base film.

[0021] In actual use, the convex strips may be hard convex strips, and the hard convex strips can be more conveniently embedded in the first strip groove and the second strip groove.

[0022] In one embodiment of the present invention, the width of the convex strip is greater than the width of the cutting channel of the wafer, and the bottom wall of the cutting channel is the upper surface of the base film or above the upper surface thereof.

[0023] In one embodiment of the present invention, the width of the convex strip is less than or equal to the width of a cutting channel of the wafer, and the bottom wall of the cutting channel is above the upper surface of the base film.

[0024] The present application also discloses a wafer to be cut structure, comprising a wafer, a FOW film, an adhesive and a base film arranged in sequence from top to bottom; The upper surface of the base film has convex strips, the wafer has a plurality of chips, and there are cutting channels between adjacent chips. The positions of the convex strips correspond to the cutting channels of the wafer, and the adhesive glue covers the upper surfaces of the base film and the convex strips.

[0025] In one embodiment of the present invention, the bonding force between the adhesive and the FOW film is smaller than the bonding force between the FOW film and the wafer.

[0026] In one embodiment of the present invention, the convex strips are arranged in a crisscross pattern.

[0027] In actual use, the convex strips may also be in other shapes corresponding to the cutting channel. For example, when the cutting channel is arc-shaped, the convex strips are also arc-shaped.

[0028] In one embodiment of the present invention, the material of the convex strips is the same as that of the base film.

[0029] In one embodiment of the present invention, the material of the convex strip is different from that of the base film. The convex strip is fixed to the upper end surface of the base film. The convex strip can be fixed on the top of the base film in a variety of ways, including but not limited to bonding, welding, etc.

[0030] The beneficial effect of the present invention is that by arranging convex strips on the base film, there are convex strips between two adjacent units after cutting to block them, which can effectively prevent the FOW film from flowing due to the influence of chip gravity and effectively prevent the FOW film from sticking. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the existing wafer structure to be cut; Figure 2 It is a schematic diagram of the non-adhesion of the FOW film after the conventional wafer is cut; Figure 3 This is a schematic diagram of the existing wafer after FOW film bonding after dicing; Figure 4 It is a schematic diagram of the structure of the wafer to be cut in the present application; Figure 5 yes Figure 4 Schematic diagram after cutting to form a cutting channel; Figure 6 yes Figure 5 Schematic diagram of the FOW membrane after separation from the adhesive glue; Figure 7 It is a partial schematic diagram of the basement membrane; Figure 8 It is a schematic diagram when the width of the convex strip is smaller than the width of the cutting channel; Fig. 9 is a schematic diagram of the cooperation between the first mold and the base film; Fig.10 is a schematic diagram of a state where the second mold and the base film are separated; Fig.11 is a schematic diagram of the second mold pressing on the upper surface of the base film; Fig.12 yes Fig.11 Schematic diagram after the second mold is removed; Fig.13 is a schematic diagram of a base film having a first strip groove and a second strip groove; Fig.14 is a schematic diagram after a convex strip is formed on the first strip groove; Fig.15It is a schematic diagram after the convex strip is formed on the second strip groove.

[0032] The reference numerals in the figures are: 1. Wafer; 11. Chip; 2. FOW film; 3. Adhesive glue; 4. Base film; 41. Raised strip; 401. First strip groove; 402. Second strip groove; 5. Cutting channel; 51. Bottom wall of cutting channel; 6. First mold; 61. Base plate; 62. Extension column; 63. Rectangular pressure plate; 64. Limiting channel; 7. Second mold; 71. Liquid injection groove; 72. Liquid injection port; 73. Exhaust port; 10. Unit. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0034] In the description of this application, it should be noted that the terms "inside", "outside", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the application is usually placed when in use, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply 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 a limitation on this application. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0035] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0036] The present invention is described in detail below in conjunction with the accompanying drawings.

[0037] This embodiment discloses a wafer cutting method, comprising the following steps: like Figure 4 , Figure 5 and Figure 7 As shown, a base film 4 is provided, and a convex strip 41 is provided on the base film 4 and protrudes from the upper surface of the base film 4, and the position of the convex strip 41 corresponds to the cutting channel 5 of the wafer 1 to be cut later; like Figure 4 As shown, a wafer 1, a FOW film 2 and an adhesive 3 are provided, the adhesive 3 covers the upper surface of the base film 4 and the convex strip 41, and the lower surface of the wafer 1 is provided with a FOW film 2, and the FOW film 2 is connected with the adhesive, that is, the wafer 1 is provided on the base film 4 and the convex strip 41 through the FOW film 2 and the adhesive. The wafer 1 has a plurality of chips, and there is a cutting channel 5 between adjacent chips, wherein the position of the convex strip 41 corresponds to the cutting channel 5; like Figure 5 As shown, the wafer 1 is cut according to the preset cutting channel 5 of the wafer 1, and the wafer 1 is cut into a plurality of chips 11, and the bottom wall 51 of the cutting channel is at least located below the upper surface of the adhesive glue 3. That is, the FOW film of adjacent units and the adhesive glue or the FOW film and the convex strip form a groove, and the groove design can cause the adhesion caused by the flow of the FOW film at the edge. It can be understood that even if the FOW film at the bottom of the edge flows slightly due to the influence of gravity, it flows along the side walls of the cutting channel, and will not form adhesion at the bottom of the edge of the FOW film of the adjacent units. In addition, the cutting channel 5 does not cut through the base film 4. It can be understood that in order to facilitate the subsequent overall demolding and separation and the overall bearing tension of the base film, the integrity of the base film 4 is ensured, that is, the bottom wall 51 of the cutting channel is located on the upper surface of the base film 4 or above it; like Figure 6 As shown, the FOW film 2 is separated from the adhesive 3 to obtain a plurality of units 10 , wherein the unit 10 includes a chip 11 and the FOW film 2 located on the lower surface of the chip 11 .

[0038] The present application provides convex strips 41 on the base film 4 so that the FOW films at the bottom of two adjacent units 10 after cutting are blocked by convex strips 41, which can effectively prevent the bottom of a large area of ​​the FOW film 2 from flowing due to the gravity of the chip 11, and can effectively prevent the FOW films 2 at the bottom of adjacent units 10 from sticking after cutting. That is, through the method of this embodiment, when the width of the cutting channel 5 becomes narrower, the FOW films 2 of adjacent units after cutting can be effectively prevented from sticking.

[0039] In this embodiment, the bonding force between the adhesive 3 and the FOW film 2 is smaller than the bonding force between the FOW film 2 and the wafer 1. This arrangement facilitates the separation of the unit 10 and prevents the chip 11 from being separated from the FOW film 2 when the FOW film 2 and the adhesive 3 are separated.

[0040] like Figure 7 As shown, in this embodiment, a plurality of convex strips 41 are arranged in a crisscross pattern.

[0041] In actual use, the convex strips 41 may also be in other shapes corresponding to the cutting channels 5. For example, when some cutting channels 5 are arc-shaped, the corresponding convex strips 41 are also arc-shaped.

[0042] like Figure 5As shown, the width of the convex strip 41 may be greater than the width of the cutting channel 5 of the wafer 1 , and at this time, the bottom wall 51 of the cutting channel is located on the upper surface of the base film 4 or above its upper surface.

[0043] like Figure 8 As shown, the width of the convex strip 41 can also be less than or equal to the width of the cutting channel 5 of the wafer 1. In this case, the bottom wall 51 of the cutting channel is above the upper surface of the base film 4 (it cannot be the upper surface of the base film 4 because the convex strip 41 is required to block the flow of the FOW film 2).

[0044] In this embodiment, the material of the convex strips 41 is the same as that of the base film 4. In other embodiments, the material of the convex strips 41 and the base film 4 may be different.

[0045] There are many ways to form convex stripes on the base film. For example, a glue coating mechanism is used to directly coat the base film with glue in a crisscross pattern as required, and the convex stripes 41 are formed after the glue is cured.

[0046] For another example, a mold may be designed to form the convex strips 41 on the base film 4 .

[0047] In one embodiment, Fig. 9 As shown, the convex strip 41 is processed by a first mold 6, and the first mold 6 includes: A base plate 61, the base plate 61 having an extending column 62 arranged downward; The rectangular pressing plates 63 are fixed below the extension pillars 62 . The lower surfaces of the rectangular pressing plates 63 are on the same horizontal plane. The gaps between the rectangular pressing plates 63 form crisscross limiting channels 64 .

[0048] During the specific operation, the base film 4 is placed directly below the first mold 6. During operation, the first mold 6 is pressed downward, and the rectangular pressing plate 63 contacts and cooperates with the base film; then the convex strip coated with bonding glue at the bottom can be placed on the limiting channel 64, or the glue liquid is coated on the limiting channel 64, and the convex strip is formed after the glue liquid is cured.

[0049] The rectangular pressing plates 63 are connected via extension columns 62 , and the extension columns 62 are parallel to each other, so as to form a larger operating space for placing the convex strips or the gluing mechanism for gluing.

[0050] In one embodiment, Fig.10 , Fig.11 and Fig.12 As shown, the convex strip 41 is processed by the second mold 7, the second mold 7 is a plate-like structure, the lower surface of the second mold 7 has liquid injection grooves 71 arranged in a criss-cross pattern, and the upper surface of the base has at least one liquid injection port 72 and at least one exhaust port 73, and the liquid injection port 72 and the exhaust port 73 are both connected to the liquid injection grooves 71.

[0051] During the specific operation, the second mold 7 is placed on the upper surface of the base film 4 so that the periphery of the second mold 7 is in sealing contact with the base film 4, and glue is injected into the injection port 72 through an injection gun. The suction gun is connected to the exhaust port 73 to discharge the air in the injection groove 71, so as to facilitate better and faster injection of the glue into the injection groove 71. After completion, the glue is cured to form a convex strip 41.

[0052] In one embodiment, Fig.13 , Fig.14 and Fig.15 As shown, the upper surface of the base film 4 has a plurality of parallel first strip grooves 401 and a plurality of parallel second strip grooves 402, and the first strip grooves 401 are perpendicular to the second strip grooves 402. At this time, the convex strip 41 can be a separate film, and the convex strip 41 can be directly embedded in the first strip groove 401 and the second strip groove 402. Because of the limiting effect of the strip grooves, the convex strip is not easy to move after being embedded. In addition to directly embedding the first strip groove 401 and the second strip groove 402, the convex strip 41 can also be embedded in the first strip groove 401 and the second strip groove 402 after applying glue, so that the convex strip can be better combined and fixed with the base film 4 after installation. In addition to being a separate film, the convex strip 41 can also be formed by glue, and the glue is injected into the first strip groove 401 and the second strip groove 402 by a glue injection mechanism, and the upper end of the glue is exposed to the upper surface of the base film 4. After the glue is solidified, the convex strip 41 is formed.

[0053] In actual use, the first strip groove 401 and the second strip groove 402 of the base film 4 can be formed when the base film 4 is processed, or can be formed separately after the base film 4 is processed, such as by pressing a mold.

[0054] In actual use, preferably, in order to ensure the structural strength of the base film 4, the base film 4 is thickened compared with the thickness of the traditional process, that is, it is a thickened base film.

[0055] In actual use, the convex strip 41 may be a hard convex strip 41 , and the hard convex strip 41 can be more conveniently embedded in the first strip groove 401 and the second strip groove 402 .

[0056] like Figure 4 As shown, this embodiment also discloses a wafer structure to be cut, which is used to implement the wafer cutting method of this embodiment. The wafer structure to be cut includes a wafer 1, a FOW film 2, an adhesive 3 and a base film 4 arranged in sequence from top to bottom; The base film 4 has a convex strip 41 protruding from the upper surface of the base film 4 , and the position of the convex strip 41 corresponds to the cutting channel 5 of the wafer 1 . The adhesive 3 covers the upper surface of the base film 4 and the convex strip 41 .

[0057] In the wafer structure to be cut, the bonding force between the adhesive 3 and the FOW film 2 is smaller than the bonding force between the FOW film 2 and the wafer 1 .

[0058] In the wafer to be cut structure, the convex strips 41 may be arranged in a crisscross pattern.

[0059] In the wafer to be cut structure, the material of the convex strip 41 and the base film 4 may be the same or different. When the material of the convex strip 41 and the base film 4 is the same, the convex strip 41 can be formed on the upper surface of the base film 4 by welding, bonding, integral molding, etc. When the material of the convex strip 41 and the base film 4 is different, the convex strip 41 can be fixed on the upper surface of the base film 4 by bonding, welding, etc.

[0060] The present application aims to reduce the flow of the FOW film by adding convex strips 41 on the base film 4, so as to improve the problem of adhesion of the cut FOW film caused by the narrow width of the cutting channel.

[0061] The above description is only a preferred embodiment of the present invention, and does not limit the patent protection scope of the present invention. Any equivalent structural transformation made by using the contents of the present invention and the drawings, directly or indirectly used in other related technical fields, is also included in the protection scope of the present invention.

Claims

1. A wafer cutting method, characterized in that: The following steps are involved: Providing a base film, wherein the base film has a convex strip protruding from the upper surface of the base film, and the position of the convex strip corresponds to a cutting channel of a wafer to be cut subsequently; Providing a wafer, a FOW film and an adhesive, wherein the adhesive covers the upper surface of the base film and the convex strips, the FOW film is disposed on the lower surface of the wafer, and the FOW film is connected to the adhesive; Cutting the wafer according to a preset wafer cutting channel to cut the wafer into a plurality of chips, wherein the bottom wall of the cutting channel is at least located below the upper surface of the adhesive, and the cutting channel does not cut through the base film; The FOW film is separated from the adhesive to obtain a plurality of units, wherein the units include a chip and the FOW film located on the lower surface of the chip.

2. The wafer cutting method according to claim 1, characterized in that: The bonding force between the adhesive and the FOW film is smaller than the bonding force between the FOW film and the wafer.

3. The wafer cutting method according to claim 1, characterized in that: The convex strips are arranged in a crisscross pattern.

4. The wafer cutting method according to claim 1, wherein: The material of the convex strips is the same as that of the base film.

5. The wafer cutting method according to claim 1, wherein: The material of the convex strip is different from that of the base film, and the convex strip is fixed on the upper end surface of the base film.

6. The wafer cutting method according to claim 1, wherein: The width of the convex strip is greater than the width of the cutting channel of the wafer, and the bottom wall of the cutting channel is on the upper surface of the base film or above its upper surface.

7. The wafer cutting method according to claim 1, characterized in that: The width of the convex strip is less than or equal to the width of the cutting channel of the wafer, and the bottom wall of the cutting channel is above the upper surface of the base film.

8. A wafer structure to be cut, characterized in that: It includes a wafer, a FOW film, an adhesive and a base film arranged in sequence from top to bottom; The base film has convex strips protruding from the upper surface of the base film, the wafer has a plurality of chips, and there are cutting channels between adjacent chips. The positions of the convex strips correspond to the cutting channels, and the adhesive glue covers the upper surfaces of the base film and the convex strips.

9. The wafer to-be-cut structure according to claim 8, characterized in that: The bonding force between the adhesive and the FOW film is smaller than the bonding force between the FOW film and the wafer.

10. The wafer to-be-cut structure according to claim 8, characterized in that: The convex strips are arranged in a crisscross pattern.

11. The wafer to-be-cut structure according to claim 8, characterized in that: The material of the convex strips is the same as that of the base film.

12. The wafer to-be-cut structure according to claim 8, characterized in that: The material of the convex strip is different from that of the base film, and the convex strip is fixed on the upper end surface of the base film.

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