Wafer cutting method

Abstract

The invention discloses a wafer cutting method, and relates to the technical field of wafer manufacturing, and the method comprises the steps: fixing a wafer, cutting a first layer of the wafer through a first cutter, forming a first cutting groove in the surface of the first layer, and enabling the depth of the first cutting groove to be smaller than the thickness of the first layer; the wafer is turned over, a second cutter is used for cutting a second layer of the wafer, a second cutting groove is formed in the surface of the second layer, the depth of the second cutting groove is smaller than the thickness of the second layer, and the projection of the first cutting groove and the projection of the second cutting groove on the surface of the wafer at least partially coincide; and sequentially cutting through the second layer and the first layer along the second cutting groove by using a third cutter. According to the invention, the first layer and the second layer are not cut through at the same time, the partial structures of the first layer and the second layer are reserved, and the wafer is cut through the third time of cutting. Therefore, when the wafer is cut in the prior art, the problems of damage and edge breakage are reduced, and the cutting quality and the processing precision of a subsequent module are improved.

Description

Technical Field

[0001] The invention relates to the technical field of wafer manufacturing, and in particular to a wafer cutting method. Background Art

[0002] Wafer cutting is an important part of the semiconductor manufacturing process. Its main function is to cut and separate multiple chips on the wafer for subsequent chip packaging and module processing. Silicon-based OLED is widely used in AR & VR devices because of its high resolution, high refresh rate and excellent display effect. However, silicon-based OLED wafers are composed of a double-layer structure of Wafer (silicon wafer) and Glass (glass). The materials of these two layers are different, so the requirements for cutting are also different.

[0003] If the same tool is used to cut the double-layer structure of Wafer and Glass at the same time, it is easy to cause more breakage problems on the Wafer layer or the Glass layer. In the related technology, although different tools are used to cut Wafer and Glass respectively, due to the high hardness and brittleness of Wafer and Glass, when the two tools completely cut through the Wafer and Glass layers respectively, the large cutting torque and travel pressure generated by the tools act on the Wafer and Glass layers, which is still easy to cause breakage and edge collapse, affecting the cutting quality and the processing of subsequent modules. Summary of the invention

[0004] The main purpose of the present invention is to provide a wafer cutting method, aiming to solve the problem that silicon-based OLED wafers are prone to breakage when being cut in the prior art.

[0005] To achieve the above object, the present invention provides a wafer cutting method, wherein the wafer includes a first layer and a second layer stacked together, and the wafer cutting method includes the steps of:

[0006] Fixing the wafer, using a first cutter to cut a first layer of the wafer, and forming a first cutting groove on a surface of the first layer, wherein the depth of the first cutting groove is less than the thickness of the first layer;

[0007] Turning over the wafer, cutting the second layer of the wafer using a second cutter, and forming a second cutting groove on the surface of the second layer, wherein the depth of the second cutting groove is less than the thickness of the second layer, and the projections of the first cutting groove and the second cutting groove on the surface of the wafer at least partially overlap;

[0008] The second layer and the first layer are cut through in sequence along the second cutting groove using a third tool.

[0009] In one embodiment of the present invention, the first layer is a silicon substrate layer, and the first cutting tool is a hard cutting tool.

[0010] In an embodiment of the present invention, the depth of the first cutting groove differs from the thickness of the silicon substrate layer by 10 um to 15 um.

[0011] In an embodiment of the present invention, the second layer is a glass layer, and the second tool is a soft tool.

[0012] In an embodiment of the present invention, the depth of the second cutting groove differs from the thickness of the glass layer by 20 um to 30 um.

[0013] In an embodiment of the present invention, the third tool is a soft tool.

[0014] In an embodiment of the present invention, the edge thickness of the first tool is a, the edge thickness of the second tool is b, and the edge thickness of the third tool is c, where a ≤ c ≤ b.

[0015] In an embodiment of the present invention, the second tool and the third tool are the same tool.

[0016] In an embodiment of the present invention, the cutting speed of the third tool is less than the cutting speed of the second tool.

[0017] In an embodiment of the present invention, the first tool, the second tool, and the third tool are all provided with a round chamfer at the edge of the blade.

[0018] In an embodiment of the present invention, the step of fixing the wafer includes:

[0019] Paste the side of the wafer facing the second layer on the surface of the blue film, and adsorb the blue film on the surface of the cutting platform.

[0020] In an embodiment of the present invention, the step of flipping the wafer and using the second tool to cut the second layer of the wafer includes:

[0021] Remove the blue film from the surface of the cutting platform;

[0022] Tear off the blue film pasted on the surface of the wafer;

[0023] Paste the side of the wafer facing the first layer on the surface of another blue film;

[0024] Adsorb the other blue film pasted on the side of the wafer facing the first layer on the surface of the cutting platform;

[0025] Use the second tool to cut the second layer of the wafer.

[0026] In an embodiment of the present invention, after the step of sequentially cutting through the second layer and the first layer along the second cutting groove using the third tool, the following steps are further included:

[0027] Removing another blue film from the surface of the cutting platform;

[0028] Tightening another blue film, and sequentially taking out a plurality of chips formed by cutting the wafer from the surface of the blue film.

[0029] The wafer cutting method proposed by the present invention is applied to the cutting of wafers with a double-layer or multi-layer structure. When cutting the wafer, first fix the wafer on the cutting platform, and then use the first tool to cut the first layer of the wafer and form a first cutting groove on the surface of the first layer, where the depth of the first cutting groove is less than the thickness of the first layer, that is, the first layer is not completely cut through. Then flip the wafer, use the second tool to cut the second layer of the wafer, and form a second cutting groove on the surface of the second layer, where the depth of the second cutting groove is less than the thickness of the second layer, that is, the second layer is not completely cut through. At the same time, the projection of the first cutting groove and the second cutting groove on the surface of the wafer at least partially overlap. Finally, use the third tool to continue cutting the second layer along the second cutting groove, and sequentially cut through the second layer and the first layer, thereby dividing the wafer into a plurality of chips. In this application, when cutting the first layer and the second layer of the wafer, two tools are respectively used for cutting, and neither the first layer nor the second layer is cut through during the cutting process, retaining part of the structures of the first layer and the second layer, and completing the division of the wafer through the third cutting. Therefore, during the existing wafer cutting, the problems of breakage and chipping are reduced, and the cutting quality and the processing accuracy of the subsequent module are improved. Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0031] Figure 1 It is a schematic structural diagram before wafer cutting;

[0032] Figure 2 It is a schematic structural diagram after cutting the first layer of the wafer using the first tool;

[0033] Figure 3 It is a schematic structural diagram after cutting the second layer of the wafer using the second tool;

[0034] Figure 4 It is a schematic structural diagram after sequentially cutting through the second layer and the first layer of the wafer using the third tool;

[0035] Figure 5 FIG. 1 is a flowchart of an embodiment of the wafer cutting method provided by the present invention;

[0036] Figure 6 is Figure 5 a flowchart of the step of fixing the wafer in FIG. 1;

[0037] Figure 7 is Figure 5 a flowchart of the steps of flipping the wafer and using a second tool to cut the second layer of the wafer in FIG. 2;

[0038] Figure 8 is Figure 5 a flowchart after the step of using a third tool to sequentially cut through the second layer and the first layer along the second cutting groove in FIG. 3.

[0039] Explanation of the reference numerals in the drawings:

[0040] 10. Wafer; 11. First layer; 111. First cutting groove; 12. Second layer; 121. Second cutting groove; 20. First tool; 30. Second tool; 40. Third tool.

[0041] The realization, functional features and advantages of the object of the present invention will be further described with reference to the embodiments and the accompanying drawings. Detailed Embodiment

[0042] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0043] It should be noted that if there are directional indications (such as up, down, left, right, front, back,...) involved in the embodiments of the present invention, the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0044] In addition, if the embodiments of the present invention involve descriptions such as "first", "second", etc., the descriptions of "first", "second", etc. are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, if "and / or" or "and / or" appears throughout the text, its meaning includes three parallel scenarios. Taking "A and / or B" as an example, it includes scenario A, or scenario B, or the scenario where both A and B are satisfied simultaneously. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement it. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0045] The present invention provides a wafer cutting method, wherein the wafer 10 includes a first layer 11 and a second layer 12 which are stacked.

[0046] Combined Figure 5 As shown, in an embodiment of the present invention, the wafer cutting method includes the steps:

[0047] S100: Fix the wafer 10, use a first tool 20 to cut the first layer 11 of the wafer 10, and form a first cutting groove 111 on the surface of the first layer 11. The depth of the first cutting groove 111 is less than the thickness of the first layer 11;

[0048] S200: Flip the wafer 10, use a second tool 30 to cut the second layer 12 of the wafer 10, and form a second cutting groove 121 on the surface of the second layer 12. The depth of the second cutting groove 121 is less than the thickness of the second layer 12. The projection of the first cutting groove 111 and the second cutting groove 121 on the surface of the wafer 10 at least partially overlaps;

[0049] S300: Use a third tool 40 to sequentially cut through the second layer 12 and the first layer 11 along the second cutting groove 121.

[0050] In this embodiment, before cutting the wafer 10, the wafer 10 needs to be fixed first to prevent the wafer 10 from moving during the cutting process. The fixing methods can be vacuum adsorption, fixture fixing, electrostatic adsorption, etc. Since the double-layer structure wafer 10 needs to cut the first layer 11 and the second layer 12 respectively, the wafer 10 is fixed first, and then the first tool 20 is used to cut the first layer 11 of the wafer 10. The material, diameter, thickness of the first tool 20 and the parameters during cutting (such as feed speed, spindle speed) can be selected according to the material structure of the first layer 11. Since the structure of the wafer 10 is generally relatively dense and has a high hardness, a large cutting torque and traveling pressure need to be provided by the first tool 20 during cutting to ensure the cutting efficiency of the first layer 11. However, the wafer 10 has the characteristic of relatively large brittleness, and the large cutting torque and traveling pressure will cause problems such as breakage or chipping at the edge of the first layer 11. Therefore, when using the first tool 20 to cut the first layer 11, the first layer 11 is not completely cut through (that is, the depth of the first cutting groove 111 is less than the thickness of the first layer 11), which can effectively reduce the occurrence of breakage and chipping of the first layer 11. Therefore, when using the first tool 20 to cut the first layer 11 and form the first cutting groove 111, when selecting the tool and adjusting the cutting parameters, it is more inclined to make the first tool 20 provide a large cutting torque and traveling pressure, so as to improve the cutting efficiency.

[0051] When the cutting of the first layer 11 is completed using the first tool 20, the wafer 10 is flipped, and the wafer 10 is fixed by means such as vacuum adsorption, fixture fixing, and electrostatic adsorption. Then the second tool 30 is used to cut the second layer 12 of the wafer 10. Similarly, the tool selection and cutting parameters of the second tool 30 can be set according to the material structure of the second layer 12. At the same time, since the second layer 12 is not completely cut through when using the second tool 30 to cut the second layer 12, more attention can be paid to increasing the cutting torque and traveling pressure when using the second tool 30 to cut the second layer 12 to improve the cutting efficiency.

[0052] When the cutting of the second layer 12 is completed using the second tool 30, the third tool 40 is used to cut the uncut parts of the second layer 12 and the first layer 11. Since the first layer 11 and the second layer 12 have been cut once through the above steps respectively, the remaining thicknesses of the first layer 11 and the second layer 12 are relatively small. Therefore, when cutting them, the main purpose of the tool selection and cutting parameter setting of the third tool 40 is to reduce breakage and chipping.

[0053] It should be noted that in the present application, the cutting tools used in the three cuts of the wafer 10 are respectively named the first cutting tool 20, the second cutting tool 30, and the third cutting tool 40 for the convenience of describing the cutting method steps. However, it does not mean that the cutting tools used in the three cuts must be three different cutting tools. For example, when the second layer 12 is glass, the second cutting tool 30 and the third cutting tool 40 can also be the same soft cutting tool.

[0054] Since the various layer structures of the wafer 10 have high hardness, a large cutting torque and traveling pressure are required during cutting. However, a large cutting torque and traveling pressure will exacerbate the breakage and chipping of the wafer 10. In addition, different cutting tools (the particle size, density, and binder composition of the cutting tool material) and cutting parameters will also affect the cutting efficiency and the degree of breakage. By adopting the above cutting method provided by the present application, when performing the first cut on the first layer 11 and the second layer 12, it is possible to focus on increasing the cutting torque and traveling pressure of the cutting tool to ensure that the cutting tool has sufficient cutting force and improve the cutting efficiency. When performing the second cut on the first layer 11 and the second layer 12, the cutting torque and traveling pressure can be appropriately reduced, or a suitable cutting tool can be selected to reduce the problems of breakage and chipping. Therefore, this cutting method provides greater flexibility for the cutting tool selection and parameter setting during the cutting of the wafer 10, while reducing the problems of breakage and chipping, improving the cutting quality and the processing accuracy of the subsequent module, so as to achieve the purpose of balancing the cutting efficiency and the cutting quality.

[0055] This cutting method is applied to the cutting of the wafer 10 with a double-layer structure. For the convenience of describing the cutting method of the present application, the present application takes a silicon-based OLED wafer as an example to introduce the technical solution of the present application. Of course, this cutting method can also be applied to the cutting of other types of wafers 10.

[0056] Combined Figure 1 and Figure 2 As shown, in an embodiment of the present invention, the first layer 11 is a silicon substrate layer, and the first cutting tool 20 is a hard cutting tool. Since the silicon substrate layer has a single-crystalline silicon structure, and single-crystalline silicon has a diamond cubic lattice structure (Diamond Cubic Structure), each silicon atom is connected to four adjacent silicon atoms through covalent bonds, forming a stable tetrahedral structure. The atomic arrangement of this structure is highly regular and ordered, making the single-crystalline silicon have high stability and uniformity.

[0057] Therefore, during the process of using a hard knife to cut the silicon substrate layer and form the first cutting groove 111, the silicon substrate layer is not prone to breakage and chipping problems. At the same time, the hard knife does not need to be installed on a dedicated tool disc and can be directly installed on the cutting machine, reducing the impact of tool disc accuracy on cutting accuracy; and the hard knife has a thinner thickness, so the resistance during cutting is smaller and the cutting speed is faster. Therefore, in this embodiment, a hard knife is selected as the first tool 20. In other embodiments, the first tool 20 can also be a soft knife.

[0058] In an embodiment of the present invention, the depth of the first cutting groove 111 differs from the thickness of the silicon substrate layer by 10 um to 15 um, that is, the uncut thickness of the silicon substrate layer is 10 um to 15 um.

[0059] When using a hard knife to cut the silicon substrate layer, although the atomic arrangement of the single-crystalline silicon structure is highly ordered, due to the large cutting torque and advancing pressure generated during cutting, the first tool 20 does not completely cut through the silicon substrate layer, which can further improve the problems of breakage and chipping. When the uncut thickness of the silicon substrate layer is less than 10 um, the thinner uncut silicon substrate layer is prone to breakage and chipping under the cutting stress of the first tool 20. In addition, since the problem of wafer 10 breakage can be improved by appropriately reducing the cutting efficiency when using the third tool 40 for cutting, when the uncut thickness of the silicon substrate layer is greater than 15 um, the thicker uncut silicon substrate layer will cause the cutting time of the third tool 40 to be too long, affecting the cutting efficiency. Therefore, when using the first tool 20 to cut the silicon substrate, in this embodiment, the uncut thickness of the silicon substrate is set to 10 um to 15 um, for example, it can be 10 um, 12 um, 15 um, etc.

[0060] Combined Figure 3 As shown, in an embodiment of the present invention, the second layer 12 is a glass layer and the second tool 30 is a soft knife. The material of the glass layer is silicon oxide, and each silicon atom forms covalent bonds with four oxygen atoms, while the oxygen atoms connect two silicon atoms to form a three-dimensional network structure. The atomic arrangement order of silicon oxide is lower than that of single-crystalline silicon, and since silicon oxide is a grid structure and there may be some local defects (vacancies, dislocations, etc.) inside the structure, when cutting the glass layer, breakage and chipping are likely to occur at the cutting edge. Therefore, in this application, a soft knife is used to cut the glass layer, and at the same time, the glass layer is not completely cut through during cutting, so the problems of breakage and chipping during the cutting of the second layer 12 can be effectively reduced, and the cutting yield can be improved.

[0061] In an embodiment of the present invention, the depth of the second cutting groove 121 differs from the thickness of the glass layer by 20 um to 30 um, that is, the uncut thickness of the glass layer is 20 um to 30 um.

[0062] When using a soft knife to cut a glass layer, although the problems of glass breakage and chipping can be improved, it is necessary to retain a certain thickness of the glass layer that is not completely cut through to further avoid breakage and chipping at the edge of the glass layer. When the thickness of the uncut-through glass layer is less than 20um, the relatively thin uncut-through glass layer is prone to breakage and chipping under the cutting stress of the second tool 30; since the cutting efficiency can be appropriately reduced when using the third tool 40 to cut to improve the problem of wafer 10 breakage, when the thickness of the uncut-through glass layer is greater than 30um, the relatively thick uncut-through glass layer will cause the cutting time of the third tool 40 to be longer, affecting the cutting efficiency. Therefore, when using the second tool 30 to cut the glass layer, the thickness of the uncut-through glass layer can be set to 20um to 30um, for example, it can be 20um, 25um, 30um, etc.

[0063] Combined with Figure 4 As shown, in an embodiment of the present invention, the third tool 40 is a soft knife. Since the third tool 40 needs to cut the uncut-through parts of the first layer 11 and the second layer 12, and the thicknesses of the uncut-through first layer 11 and the second layer 12 are relatively thin, breakage and chipping are likely to occur during cutting. Therefore, a soft knife is selected as the third tool 40.

[0064] At the same time, since the thicknesses of the first layer 11 and the second layer 12 that the third tool 40 needs to cut are relatively thin and the cutting time is short, the third tool 40 can focus more on improving the problems of breakage and chipping during cutting. For example, when the tool material is diamond, diamond particles with different particle sizes and densities or different types of adhesives can be combined, or the cutting parameters can be adjusted to reduce the problem of cutting breakage. Therefore, this cutting method provides higher flexibility for the selection of tools and the setting of parameters, so that when the process personnel cut the wafer 10, they can achieve the purpose of taking into account both cutting efficiency and cutting quality through tool selection and parameter adjustment.

[0065] Combined with Figure 4 As shown, in an embodiment of the present invention, the edge thickness of the first tool 20 is a, the edge thickness of the second tool 30 is b, and the edge thickness of the third tool 40 is c, where a ≤ c ≤ b.

[0066] In this embodiment, when using the third tool 40 to cut the uncut-through parts of the first layer 11 and the second layer 12, since the third tool 40 cuts the second layer 12 and the first layer 11 in sequence along the second cutting groove 121, the width of the second cutting groove 121 is also the edge thickness b of the second tool 30. Therefore, the edge thickness c of the third tool 40 is designed to be c ≤ b, so that when using the third tool 40 to cut, it can be avoided that the third tool 40 increases the width of the second cutting groove 121, so as to prevent the cut part of the second layer 12 from being cut again.

[0067] In addition, as described above, the material of the first layer 11 is a silicon substrate, and the arrangement of single-crystalline silicon atoms is more orderly. Using a hard knife for cutting can improve the cutting efficiency and cutting accuracy; the material of the second layer 12 is glass, and a soft knife is used for cutting to ensure the cutting quality. Since the blade thickness of the hard knife can be made thinner than that of the soft knife, a thinner blade thickness can reduce material loss and improve cutting efficiency. Therefore, designing the blade thickness a of the first tool 20 to be a ≤ c can not only improve the cutting efficiency on the silicon substrate side, but also make the area of the cut chip substrate side greater than or equal to the area of the glass side, that is, the area of the side where the chip contacts the packaging substrate is larger, thereby improving the reliability of subsequent chip packaging.

[0068] In an embodiment of the present invention, the second tool 30 and the third tool 40 are the same tool. At this time, after cutting the second layer 12 to form the second cutting groove 121, there is no need to change the tool, and the same soft knife can be used to cut the uncut part of the second layer 12 and the first layer 11 along the second cutting groove 121, thereby improving the overall cutting efficiency.

[0069] In an embodiment of the present invention, the cutting speed of the third tool 40 is less than the cutting speed of the second tool 30. Since when using the second tool 30 to cut the second layer 12, the second layer 12 is not completely cut through; when using the third tool 40 to cut the second layer 12 and the first layer 11, the uncut part of the second layer 12 needs to be cut off. Therefore, compared with the third tool 40, it is less likely to cause breakage and chipping problems when using the second tool 30 to cut the second layer 12. Therefore, the cutting speed when using the third tool 40 can be set to be less than the cutting speed of the second tool 30, so that the second tool 30 can complete the cutting faster and at the same time reduce the problems of breakage and chipping when using the third tool 40 for cutting.

[0070] Of course, the change in cutting speed is only an embodiment of the inventive concept of the present application for three times of cutting the double-layer structure wafer 10, and by adjusting process parameters to balance cutting efficiency and cutting quality. It is also possible to improve or adjust the material, model, size of the tool, and other process parameters during different cutting steps to improve the convenience of process adjustment.

[0071] Combined with Figures 2 to 4As shown, in an embodiment of the present invention, the first tool 20, the second tool 30, and the third tool 40 are all provided with rounded chamfers at the edge of the cutting edge. By setting the rounded chamfers, the stress can be dispersed over a larger area, avoiding stress concentration at the acute or sharp corners of the tool, thereby reducing the risk of breakage and chipping of the wafer 10 during the cutting process. At the same time, setting rounded chamfers at the edge of the cutting edge of the tool can also reduce the number of burrs generated during the cutting of the wafer 10, enabling the edge of the cut chip to be smoother, thereby improving the accuracy of the chip position recognition by the packaging equipment during the subsequent chip packaging process.

[0072] Combined with Figure 6 As shown, in an embodiment of the present invention, the steps of fixing the wafer 10 include:

[0073] S110: Paste one side of the wafer 10 facing the second layer 12 on the surface of the blue film, and adsorb the blue film on the surface of the cutting platform.

[0074] In this embodiment, the surface of the blue film is coated with an adhesive, and the wafer 10 is fixed on the surface of the blue film by pasting to ensure that the wafer 10 does not slide relative to the blue film during subsequent cutting operations. Then, the blue film with the wafer 10 pasted on it is fixed on the surface of the cutting platform by vacuum adsorption, so that the wafer 10 and the cutting platform are relatively fixed. The blue film has good toughness. The wafer 10 is adsorbed and fixed on the cutting platform through the blue film, which can buffer the mechanical stress and cutting stress received by the wafer 10, reducing the problems of scratches and breakage on the surface of the wafer 10.

[0075] Combined with Figure 7 As shown, in an embodiment of the present invention, in the step of flipping the wafer 10 and using the second tool 30 to cut the second layer 12 of the wafer 10, it includes:

[0076] S210: Remove the blue film from the surface of the cutting platform;

[0077] S220: Tear off the blue film pasted on the surface of the wafer 10;

[0078] S230: Paste one side of the wafer 10 facing the first layer 11 on the surface of another blue film;

[0079] S240: Adsorb the other blue film pasted on one side of the wafer 10 facing the first layer 11 on the surface of the cutting platform;

[0080] S250: Use the second tool 30 to cut the second layer 12 of the wafer 10.

[0081] In this embodiment, after the first layer 11 is cut using the first cutting tool 20, the vacuum adsorption device of the cutting platform is turned off. Then, the first blue film with the wafer 10 adhered thereto is removed from the cutting platform, and the first blue film adhered to the surface of the wafer 10 is torn off. During the tearing process, ultraviolet light can be irradiated on the blue film first to harden the adhesive on the surface of the blue film, so as to avoid the adhesive remaining on the surface of the wafer 10 when the blue film is torn off.

[0082] Then, the first layer 11 of the wafer 10 is adhered to the surface of another blue film, the second blue film with the wafer 10 adhered thereto is placed on the surface of the cutting platform, and the vacuum adsorption device is started to adsorb the blue film on the cutting platform. Then, the second layer 12 of the wafer 10 is cut using the second cutting tool 30.

[0083] Combined Figure 8 As shown, in an embodiment of the present invention, after the step of using the third cutting tool 40 to sequentially cut through the second layer 12 and the first layer 11 along the second cutting groove 121, the following steps are further included:

[0084] S400: Remove another blue film from the surface of the cutting platform;

[0085] S500: Tighten another blue film, and sequentially take out the multiple chips formed by cutting the wafer 10 from the surface of the blue film.

[0086] In this embodiment, after the second layer 12 is cut using the second cutting tool 30, the vacuum adsorption device is turned off. Then, the second blue film with the wafer 10 adhered thereto is removed from the cutting platform. Then, the blue film is placed on the tensioning device. The tensioning device applies a uniform pulling force to the blue film by mechanical or pneumatic means to make the surface of the blue film flat and reduce wrinkles. After the blue film is tensioned, the multiple chips formed by cutting the wafer 10 will be spaced apart on the surface of the blue film, facilitating subsequent taking-out operations.

[0087] The above is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structural transformation made under the technical concept of the present invention by using the content of the specification and drawings of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A wafer cutting method, characterized in that, The wafer includes a first layer and a second layer which are stacked, and the wafer cutting method includes the steps: Fix the wafer, use a first tool to cut the first layer of the wafer, and form a first cutting groove on the surface of the first layer, and the depth of the first cutting groove is less than the thickness of the first layer; Flip the wafer, use a second tool to cut the second layer of the wafer, and form a second cutting groove on the surface of the second layer, and the depth of the second cutting groove is less than the thickness of the second layer, and at least part of the projections of the first cutting groove and the second cutting groove on the wafer surface coincide; Use a third tool to sequentially cut through the second layer and the first layer along the second cutting groove.

2. The wafer cutting method according to claim 1, wherein The first layer is a silicon substrate layer, and the first tool is a hard tool.

3. The wafer cutting method according to claim 2, wherein, The difference between the depth of the first cutting groove and the thickness of the silicon substrate layer is 10um - 15um.

4. The wafer cutting method according to claim 1, wherein, The second layer is a glass layer, and the second tool is a soft tool.

5. The wafer cutting method according to claim 4, wherein, The difference between the depth of the second cutting groove and the thickness of the glass layer is 20um - 30um.

6. The wafer cutting method according to claim 1, characterized in that, The third tool is a soft tool.

7. The wafer cutting method according to any one of claims 2 to 6, characterized in that, The edge thickness of the first tool is a, the edge thickness of the second tool is b, and the edge thickness of the third tool is c, where a ≤ c ≤ b.

8. The wafer cutting method according to claim 7, wherein, The second tool and the third tool are the same tool.

9. The wafer cutting method according to any one of claims 1 to 6, characterized in that, The cutting speed of the third tool is less than the cutting speed of the second tool.

10. The wafer cutting method according to any one of claims 1 to 6, characterized in that, The first tool, the second tool, and the third tool are all provided with a round chamfer at the edge of the cutting edge.

11. The wafer cutting method according to any one of claims 1 to 6, characterized in that, The step of fixing the wafer includes: Paste the side of the wafer facing the second layer on the surface of the blue film, and adsorb the blue film on the surface of the cutting platform.

12. The wafer cutting method according to claim 11, wherein The step of flipping the wafer and using the second tool to cut the second layer of the wafer includes: Remove the blue film from the surface of the cutting platform; Tear off the blue film pasted on the surface of the wafer; Paste the side of the wafer facing the first layer on the surface of another blue film; Adsorb another blue film pasted on the side of the wafer facing the first layer on the surface of the cutting platform; Use the second tool to cut the second layer of the wafer.

13. The wafer cutting method according to claim 12, wherein, After the step of using the third tool to sequentially cut through the second layer and the first layer along the second cutting groove, it further includes: Remove another blue film from the surface of the cutting platform; Tighten another blue film, and sequentially take out the multiple chips formed by cutting the wafer from the surface of the blue film.

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