Wafer cutting method

Abstract

The invention discloses a wafer cutting method, and relates to the technical field of wafer cutting processing. The wafer comprises a front face and a back face which are oppositely arranged, the front face is provided with a plurality of chip function areas and cutting channel areas located between every two adjacent chip function areas, and the wafer cutting method comprises the steps that a front face protection film is attached to the front face of the wafer; carrying out thinning processing on the back surface of the wafer so that the wafer is thinned to a preset thickness; removing the protective film on the front surface, and pasting a through cutting film on the back surface of the wafer; performing laser grooving treatment on the front surface of the wafer corresponding to the cutting channel region; performing back laser transmission invisible cutting on the wafer subjected to the laser slotting treatment corresponding to the cutting channel region, so that the wafer is divided into a plurality of core particles; and stretching the through cutting film so as to enable two adjacent core particles in the wafer to generate an interval, and carrying out material taking treatment on the core particles. According to the method, the steps are few, the film reversing process from grooving to hidden cutting is omitted, the wafer cutting efficiency can be improved, the fragment rate is reduced, the number of core particles is increased, and the machining cost of a single core particle is reduced.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 2023107490208, filed on June 25, 2023, and entitled “Wafer Cutting Method”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present invention relates to the technical field of wafer cutting processing, and in particular to a wafer cutting method. Background Art

[0004] Wafers are also called silicon chips. Circuit components such as chips can be manufactured by setting chip circuit structures (such as transistors, etc.) on the surface of the wafer. In order to save manufacturing costs and improve manufacturing efficiency, in mass production, multiple (such as 500) chip circuit structures are often set on the same wafer, and then the wafer is cut along the gaps between adjacent circuit structures, so that multiple chips can be obtained based on the same wafer.

[0005] With the development of chip miniaturization, the thickness of wafers has gradually decreased from the traditional 700 microns to less than 200 microns. The traditional mechanical cutting processing method can ensure a higher yield and chip reliability for traditional wafers with a thickness of more than 700 microns. However, for wafers below 200 microns, the high-speed rotation of the cutter wheel used in the traditional mechanical grinding method will inevitably cause risks such as cracks, broken edges and broken pieces due to direct contact with the chip while achieving physical separation of the chip. In response to the above problems, laser cutting has been proposed on the market to replace cutter wheel cutting, which can solve the problem of chip yield very well. However, the existing laser cutting method for wafer cutting has many processes and cumbersome steps, which greatly restricts the processing efficiency. Summary of the invention

[0006] The object of the present invention is to provide a wafer cutting method, which has fewer steps and can improve the efficiency of wafer cutting.

[0007] The embodiment of the present invention is achieved as follows:

[0008] In one aspect of the present invention, a wafer cutting method is provided, wherein the wafer comprises a front side and a back side which are arranged opposite to each other, the front side having a plurality of chip functional areas and a cutting path area between two adjacent chip functional areas, and the wafer cutting method comprises: attaching a front protective film to the front side of the wafer; performing a thinning process on the back side of the wafer to thin the wafer to a preset thickness; removing the front protective film and attaching a through-cutting film to the back side of the wafer; performing a laser grooving process on the front side of the wafer corresponding to the cutting path area; performing a back side laser transmission invisible cutting on the wafer after the laser grooving process corresponding to the cutting path area to divide the wafer into a plurality of core particles; stretching the through-cutting film to generate a gap between two adjacent core particles in the wafer, and performing a material extraction process on the core particles. The wafer cutting method has fewer steps and can improve the efficiency of wafer cutting.

[0009] Optionally, the preset thickness is between 70 μm and 200 μm.

[0010] Optionally, the front protective film is removed and a through-cut film is attached to the back of the wafer, including: removing the front protective film and attaching the through-cut film to the back of the wafer, the through-cut film having a light-transmitting wavelength range of 900nm to 1300nm, a laser transmittance greater than 95%, and a thickness of 20μm to 50μm.

[0011] Optionally, laser grooving is performed on the front side of the wafer corresponding to the cutting lane area, including: coating a front side protective liquid on the chip functional surface of the front side of the wafer; laser grooving is performed on the front side of the wafer corresponding to the cutting lane area, wherein during the laser grooving, the laser band is between 300nm and 1100nm, the pulse width is between 800ps and 100ns, the power is between 5W and 30W, and the grooving speed is between 400mm / s and 2000mm / s; and removing the front side protective liquid.

[0012] Optionally, the groove width of the wafer is between 10 μm and 80 μm, and the groove depth is between 4 μm and 50 μm.

[0013] Optionally, the corresponding cutting zone performs back-side laser transmission stealth cutting on the wafer after the laser grooving process so that the wafer is divided into multiple core particles, including: placing the wafer after the laser grooving process with the front side facing down in the laser stealth cutting machine, and vacuum adsorbing the wafer through the adsorption mechanism of the laser stealth cutting machine; performing back-side laser transmission stealth cutting on the wafer after the laser grooving process in the corresponding cutting zone so that the wafer is divided into multiple core particles.

[0014] Optionally, the wafer after the laser grooving process is placed face down in a laser stealth cutting machine, and the wafer is vacuum adsorbed by the adsorption mechanism of the laser stealth cutting machine, including: placing the wafer after the laser grooving process face down in the laser stealth cutting machine; adjusting the flatness of the wafer by the lifting platform of the laser stealth cutting machine so that the flatness deviation value of the wafer after the flatness adjustment is between 3μm and 6μm; and vacuum adsorbing the wafer by the adsorption mechanism of the laser stealth cutting machine.

[0015] Optionally, the through-cut film is stretched to create a gap between two adjacent core particles in the wafer, and the core particles are processed for material removal, including: debonding the through-cut film; expanding the debonded wafer to create a gap between two adjacent core particles, wherein the spacing distance between two adjacent core particles is between 10μm and 100μm; and removing a single core particle from the wafer after the expansion process.

[0016] Optionally, the through-cut film is subjected to a debonding treatment, including: irradiating the through-cut film with ultraviolet rays to release the adhesion between the through-cut film and the wafer.

[0017] Optionally, the through-cut film is a UV adhesive film.

[0018] The beneficial effects of the present invention include:

[0019] The present application provides a wafer cutting method, wherein the wafer comprises a front side and a back side arranged relatively to each other, the front side having a plurality of chip functional areas and a cutting path area located between two adjacent chip functional areas, and the wafer cutting method comprises: sticking a front side protective film on the front side of the wafer; performing a thinning process on the back side of the wafer to thin the wafer to a preset thickness; removing the front side protective film and sticking a through-cutting film on the back side of the wafer; performing a laser grooving process on the front side of the wafer corresponding to the cutting path area; performing a back side laser transmission invisible cutting on the wafer after the laser grooving process corresponding to the cutting path area to divide the wafer into a plurality of core particles; stretching the through-cutting film to create a gap between two adjacent core particles in the wafer, and performing a material extraction process on the core particles. The wafer cutting method provided in the present application thins the back of the wafer, performs laser grooving on the front of the wafer, and then performs laser transmission invisible cutting on the back of the wafer. This cutting method can reduce the probability of edge chipping and fragmentation, and greatly improves the yield of wafer cutting. In addition, the present application adopts laser cutting, and its laser spot is small, which can support the cutting of wafers with a smaller cutting zone width, and can increase the number of core particles in a wafer, and has a better market application prospect. Moreover, the laser equipment has very few consumables, especially for laser invisible cutting equipment, which has almost no consumables, and can also reduce the cost of wafer cutting. In addition, the wafer cutting method provided in the present application has fewer steps, omitting the film inversion process from grooving to invisible cutting, which can improve the efficiency of wafer cutting and reduce the fragmentation rate. Compared with the traditional slotting + water jet processing method, slotting + hidden cutting has faster processing efficiency, the processing speed is increased from 50mm / s to more than 80mm / s, the processing time is increased by more than 30%, and the cutting path spacing can be shortened from 60μm to 20μm, the number of core particles is increased by 5% to 10%, and the processing cost of a single core particle is reduced. In addition, the application is simple to operate, and compared with the existing technology, the process of the existing technology can be effectively shortened, which can improve the yield and efficiency of the overall process and reduce the risk points in multiple processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 One of the flow diagrams of the wafer cutting method provided by the embodiment of the present invention;

[0022] Figure 2 One of the preparation process diagrams for wafer cutting provided by an embodiment of the present invention;

[0023] Figure 3FIG2 is a second diagram of a preparation process for wafer cutting provided by an embodiment of the present invention;

[0024] Figure 4 Figure 3 of the preparation process for wafer cutting provided by an embodiment of the present invention;

[0025] Figure 5 FIG. 4 is a preparation process diagram of wafer cutting provided by an embodiment of the present invention;

[0026] Figure 6 Figure 5 of the preparation process for wafer cutting provided by an embodiment of the present invention;

[0027] Figure 7 Figure 6 of the preparation process for wafer cutting provided by an embodiment of the present invention;

[0028] Figure 8 Figure 7 of the preparation process for wafer cutting provided by an embodiment of the present invention;

[0029] Fig. 9 Figure 8 of the preparation process of wafer cutting provided by an embodiment of the present invention;

[0030] Fig.10 Figure 9 of the preparation process for wafer cutting provided by an embodiment of the present invention;

[0031] Fig.11 A second flow chart of a wafer cutting method provided by an embodiment of the present invention;

[0032] Fig.12 A third flow chart of a wafer cutting method provided by an embodiment of the present invention;

[0033] Fig.13 A fourth flow chart of a wafer cutting method provided by an embodiment of the present invention;

[0034] Fig.14 The fifth flowchart of the wafer cutting method provided in the embodiment of the present invention.

[0035] Icon: 10-wafer; 20-front protective film; 30-through-cut film; 40-front protective liquid. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, 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 described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0037] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. 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.

[0038] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0039] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0040] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0041] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" 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 mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected 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 the present invention can be understood according to specific circumstances.

[0042] Please refer to Figure 1 This embodiment provides a wafer cutting method, wherein the wafer 10 includes a front side and a back side that are arranged opposite to each other, the front side has a plurality of chip functional areas and a cutting road area between two adjacent chip functional areas, and the wafer cutting method includes:

[0043] S100, attaching a front protection film 20 to the front side of the wafer 10, such as Figure 2 .

[0044] It should be noted that the wafer 10 is a wafer 10 that has been subjected to a grinding and thinning process, and the wafer 10 includes a front side and a back side arranged opposite to the front side.

[0045] In this embodiment, the thickness of the wafer 10 is 770 μm, and the above step S100 is performed after the chip pattern is formed on the front side of the wafer 10. That is, step S100 is performed after the chip pattern is formed on the front side of the wafer 10 (that is, after the chip pattern is formed in the chip functional area of ​​the wafer 10).

[0046] In addition, the thickness of the above-mentioned wafer 10 of 770 μm is only an example given in the present application, and is not the only limitation on the thickness value of the wafer 10 . Those skilled in the art can select a wafer 10 of any thickness according to actual conditions.

[0047] In addition, the material of the front protection film 20 is not limited in this application, and those skilled in the art can choose it according to actual conditions, for example, BG film can be selected. It should be noted that the front protection film 20 needs to be able to protect the front side of the wafer 10 to avoid damage to the front side of the wafer 10 (especially to avoid damage to the chip functional area on the front side of the wafer 10) when the back side of the wafer 10 is subsequently thinned.

[0048] S200, performing a thinning process on the back side of the wafer 10 to thin the wafer 10 to a preset thickness, such as Figure 3 .

[0049] It should be noted that the step S200 may be specifically performed by placing the wafer 10 in a thinning machine and then thinning the wafer 10 using the thinning machine.

[0050] Optionally, the preset thickness is between 70 μm and 200 μm. For example, the preset thickness may be 70 μm, 100 μm, 150 μm, 180 μm or 200 μm.

[0051] Of course, the above preset thickness is only an example of the present application, and those skilled in the art may also appropriately increase or decrease the preset thickness according to different chip types.

[0052] S300, remove the front protective film 20, and attach a through-cut film 30 to the back of the wafer 10, as shown in FIG. Figure 4 .

[0053] That is, after the back side of the wafer 10 is thinned, the front protection film 20 on the front side of the wafer 10 can be removed. Since the back side of the wafer 10 needs to be invisible cut later, a through-cut film 30 needs to be attached to the back side of the wafer 10 in step S300.

[0054] Optionally, the step S300 of removing the front protective film 20 and attaching a through-cut film 30 to the back side of the wafer 10 includes:

[0055] The front protection film 20 is removed, and a through-cut film 30 is attached to the back of the wafer 10 . The through-cut film 30 has a light-transmitting wavelength range of 900 nm to 1300 nm, a laser transmittance greater than 95%, and a thickness of 20 μm to 50 μm.

[0056] That is, the through-cut film 30 attached to the back side of the wafer 10 in the above step S300 can transmit the laser beam with a wavelength between 900 nm and 1300 nm, and can transmit more than 95% of the laser beam.

[0057] For example, the thickness of the through-cut film 30 may be 20 μm, 30 μm, 40 μm or 50 μm.

[0058] S400, laser grooving is performed on the front side of the wafer 10 corresponding to the dicing area, such as Figure 8 .

[0059] That is, after executing step S300, the front side of the wafer 10 can be laser grooved, so that the following Figure 8 In the structure shown in FIG. 1 , at this time, a groove is formed on the front side of the wafer 10 corresponding to the scribe line area.

[0060] Optionally, the slot width of the wafer 10 is between 10 μm and 80 μm, and the slot depth is between 4 μm and 50 μm, that is, the slot width along the first direction is between 10 μm and 80 μm, wherein the first direction is the arrangement direction of two adjacent chip functional areas on the wafer 10 .

[0061] For example, the groove width of the wafer 10 may be 10 μm, 20 μm, 50 μm, 70 μm or 80 μm, etc.; the groove depth of the wafer 10 may be 4 μm, 10 μm, 30 μm or 50 μm, etc.

[0062] For example, please refer to Fig.11 Optionally, the above step S400, performing laser grooving processing on the front side of the wafer 10 corresponding to the dicing area, may specifically include the following steps:

[0063] S410, coating the front protective liquid 40 on the chip functional surface of the front side of the wafer 10, such as Figure 5 .

[0064] In this way, when the front side of the wafer 10 is laser grooved, damage to the chip functional surface of the wafer 10 can be avoided, thereby improving the quality of the wafer 10 .

[0065] S420, laser grooving is performed on the front side of the wafer 10 corresponding to the dicing area, such as Figure 6 and Figure 7 During the laser grooving process, the laser wavelength is between 300nm and 1100nm, the pulse width is between 800ps and 100ns, the power is between 5W and 30W, and the grooving speed is between 400mm / s and 2000mm / s.

[0066] That is, after the front surface protective liquid 40 is applied to the chip functional surface of the front surface of the wafer 10 for protection, the laser groove processing is performed on the front surface of the wafer 10 .

[0067] The above parameters for the laser grooving process are only examples, and those skilled in the art can make corresponding selections within the above ranges according to actual needs.

[0068] S430, removing the front protection liquid 40, such as Figure 8 .

[0069] That is, the front protection liquid 40 is removed after the front surface of the wafer 10 is laser grooved. The method of removing the front protection liquid 40 is not specifically limited in this application, and those skilled in the art can select it according to the specific type of the front protection liquid 40.

[0070] S500, performing back-side laser transmission invisible cutting on the wafer 10 after the laser grooving process corresponding to the cutting path area, so that the wafer 10 is divided into a plurality of core particles, such as Fig. 9 and Fig.10 .

[0071] The present application performs laser transmission invisible cutting on the back side of the wafer 10, so that direct contact between mechanical parts and the wafer 10 can be avoided during cutting, the risk of cracks, edge collapse and fragmentation can be reduced, thereby improving the cutting yield.

[0072] In addition, the present application performs laser cutting on the front side of the wafer 10 and performs invisible laser transmission cutting on the back side of the wafer 10, which can also increase the number of core grains in a wafer 10. Generally, the width of the cutting road area of ​​a traditional wafer 10 is 60 μm. The wafer cutting method provided by the present application can support the cutting of a wafer 10 with a cutting road area width of 20 μm. Therefore, the number of core grains in the wafer 10 can be increased by about 5% to 10%, which has a better market application prospect.

[0073] Please refer to Fig.12 Optionally, the above step S500, corresponding to the cutting road area, performs back-side laser transmission invisible cutting on the wafer 10 after the laser grooving process, so that the wafer 10 is divided into a plurality of core particles, which can be specifically implemented in the following manner:

[0074] S510, placing the wafer 10 after the laser grooving process face down in a laser stealth cutting machine, and vacuum adsorbing the wafer 10 through the adsorption mechanism of the laser stealth cutting machine.

[0075] S520 , performing back-side laser transmission invisible dicing on the wafer 10 after the laser grooving process corresponding to the dicing street area, so that the wafer 10 is divided into a plurality of core particles.

[0076] Among them, for example, the above-mentioned laser invisible cutting machine can use a high NA value objective lens to shape the incident light spot so that the cutting film 30 is not damaged during processing; the NA value of the objective lens used is in the range of 0.5-0.9; the light spot shaping method is not limited to slits, diffraction mirrors, beam reducers, etc.

[0077] In addition, the speed of laser invisible cutting can be between 200mm / s and 1500mm / s, the laser operating band can be between 900nm and 1300nm, the pulse width can be between 10ps and 500ns, and the power can be between 3W and 20W.

[0078] It should be noted that when the front side of the wafer 10 is placed face down in the laser stealth cutting machine and the back side of the wafer 10 is subjected to laser stealth cutting, cracks will be generated in the wafer 10 due to internal tension after the laser stealth cutting and extend to the surface of the wafer 10, thereby separating the core particles of the wafer 10 (i.e., dividing them into multiple core particles).

[0079] Please refer to Fig.13 Optionally, the above step S510, placing the wafer 10 after laser grooving with its front side facing downward in a laser stealth cutting machine, and vacuum adsorbing the wafer 10 through the adsorption mechanism of the laser stealth cutting machine, can be specifically implemented in the following manner:

[0080] S511, placing the wafer 10 after the laser grooving process with its front side facing downward in a laser stealth cutting machine.

[0081] The front side of the wafer 10 faces downward, so that the front side of the wafer 10 is placed on the soft receiving table of the laser stealth cutting machine to avoid damage to the front side of the wafer 10 .

[0082] S512, adjusting the flatness of the wafer 10 by means of the lifting platform of the laser stealth cutting machine, so that the flatness deviation value of the wafer after the flatness adjustment is between 3 μm and 6 μm.

[0083] In this embodiment, the flexible receiving platform is composed of an inner ceramic disk and an outer ceramic disk, wherein the inner ceramic disk can be lifted and lowered by a lifting platform to adjust the overall flatness of the wafer 10. The flatness deviation value of the wafer after flatness adjustment can be 3μm, 4μm, 5μm or 6μm, etc.

[0084] S513 , vacuum adsorbing the wafer 10 through the adsorption mechanism of the laser stealth cutting machine.

[0085] The present application does not impose any restriction on the specific structural form of the adsorption mechanism, as long as it can cooperate with the flexible receiving platform to adsorb the wafer 10 on the flexible receiving platform so that the wafer 10 is relatively fixed.

[0086] S600 , stretching the through-cut film 30 to create a gap between two adjacent core particles in the wafer 10 , and performing a material removal process on the core particles.

[0087] After executing step S500 , the through-cut film 30 is stretched so that a gap is created between two adjacent core particles in the wafer 10 , so that the core particles can be removed.

[0088] The method of removing the transparent film 30 is determined according to the specific type of the transparent film 30 , and the present application does not limit it. For example, optionally, the transparent film 30 is a UV adhesive film.

[0089] So, please refer to Fig.14 Optionally, the above step S600, stretching the through-cut film 30 to create a gap between two adjacent core particles in the wafer 10, and performing a material removal process on the core particles, can be specifically implemented in the following manner:

[0090] S610 , performing a debonding process on the through-cut film 30 .

[0091] S620 , performing wafer expansion processing on the debonded wafer 10 to create a gap between two adjacent core particles, wherein the gap between the two adjacent core particles is between 10 μm and 100 μm.

[0092] S630 , taking out a single die from the wafer 10 after the wafer expansion process.

[0093] Wherein, optionally, the above step S610, performing a debonding process on the through-cut film 30, specifically includes:

[0094] The through-cut film 30 is irradiated with ultraviolet rays to release the adhesion between the through-cut film 30 and the wafer 10 .

[0095] In the present application, after the transparent film 30 is irradiated with ultraviolet rays, the stickiness of the transparent film 30 can be released, so that the wafer 10 can be expanded to separate two adjacent core particles, thereby facilitating the removal of the core particles.

[0096] In summary, the present application provides a wafer cutting method, wherein the wafer 10 includes a front side and a back side relatively arranged, the front side having multiple chip functional areas and a cutting path area located between two adjacent chip functional areas, and the wafer cutting method includes: attaching a front protective film 20 to the front side of the wafer 10; thinning the back side of the wafer 10 to thin the wafer 10 to a preset thickness; removing the front protective film 20 and attaching a through-cutting film 30 to the back side of the wafer 10; laser grooving the front side of the wafer 10 corresponding to the cutting path area; performing back-side laser transmission invisible cutting on the laser-grooved wafer 10 corresponding to the cutting path area to divide the wafer 10 into multiple core particles; stretching the through-cutting film to create a gap between two adjacent core particles in the wafer, and performing material extraction on the core particles. The wafer cutting method provided in the present application performs thinning processing on the back side of the wafer 10, performs laser grooving on the front side of the wafer 10, and then performs laser invisible cutting on the back side of the wafer 10. This cutting method can reduce the probability of edge chipping and fragmentation, and greatly improves the yield rate of wafer 10 cutting. In addition, the present application adopts laser cutting, and its laser spot is small, which can support the cutting of wafers 10 with a smaller cutting zone width, and can increase the number of core particles in a wafer 10, and has a better market application prospect. Moreover, the laser equipment has very few consumables, especially for laser invisible cutting equipment, which has almost no consumables, and can also reduce the cutting cost of the wafer 10. In addition, the wafer cutting method provided in the present application has fewer steps, and the film inversion process from grooving to invisible cutting is omitted, which can improve the efficiency of wafer 10 cutting and reduce the fragmentation rate. Compared with the traditional slotting + water jet processing method, slotting + hidden cutting has faster processing efficiency, the processing speed is increased from 50mm / s to more than 80mm / s, the processing time is increased by more than 30%, and the cutting path spacing can be shortened from 60μm to 20μm, the number of core particles is increased by 5% to 10%, and the processing cost of a single core particle is reduced. In addition, the application is simple to operate, and compared with the existing technology, the process of the existing technology can be effectively shortened, which can improve the yield and efficiency of the overall process and reduce the risk points in multiple processes.

[0097] It should be noted that the existing laser cutting process has the following eleven steps: sticking a blue film on the back of the wafer 10; laser grooving; tearing off the blue film and removing the steel ring; sticking a film on the front of the wafer 10; thinning the wafer 10 with a grinder; sticking a film on the back of the wafer 10; laser hidden cutting on the back; debonding the film on the front of the wafer 10; tearing off the film on the front of the wafer 10; debonding the film on the back of the wafer 10; and separating the chips.

[0098] The above description is only an optional embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0099] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A wafer cutting method, wherein the wafer comprises a front side and a back side arranged opposite to each other, the front side has a plurality of chip functional areas and a cutting path area between two adjacent chip functional areas, characterized in that: The wafer cutting method comprises: affixing a front protective film on the front side of the wafer; Performing a thinning process on the back side of the wafer to thin the wafer to a preset thickness; removing the front protective film and attaching a through-cut film to the back of the wafer; Performing laser grooving processing on the front side of the wafer corresponding to the dicing area; Performing back-side laser transmission invisible cutting on the wafer after laser grooving corresponding to the cutting street area, so that the wafer is divided into a plurality of core particles; The through-cut film is stretched to create a gap between two adjacent core particles in the wafer, and the core particles are removed.

2. The wafer cutting method according to claim 1, characterized in that: The preset thickness is between 70 μm and 200 μm.

3. The wafer cutting method according to claim 1, characterized in that: The method of removing the front protective film and attaching a through-cut film to the back of the wafer includes: The front protective film is removed, and a through-cut film is attached to the back of the wafer, wherein the light-transmitting wavelength range of the through-cut film is between 900nm and 1300nm, the laser transmittance is greater than 95%, and the thickness of the through-cut film is between 20μm and 50μm.

4. The wafer cutting method according to claim 1, characterized in that: The laser grooving process is performed on the front side of the wafer corresponding to the scribe line area, including: Coating a front protection liquid on the chip functional surface on the front side of the wafer; Performing laser grooving processing on the front side of the wafer corresponding to the cutting road area, wherein during the laser grooving processing, the laser wavelength is between 300nm and 1100nm, the pulse width is between 800ps and 100ns, the power is between 5W and 30W, and the grooving speed is between 400mm / s and 2000mm / s; The front protection liquid is removed.

5. The wafer cutting method according to claim 4, characterized in that: The wafer has a groove width between 10 μm and 80 μm, and a groove depth between 4 μm and 50 μm.

6. The wafer cutting method according to claim 1, characterized in that: The step of performing back-side laser transmission invisible cutting on the wafer after the laser grooving process corresponding to the cutting road area so as to divide the wafer into a plurality of core particles includes: Placing the wafer after laser grooving with its front side facing downward in a laser stealth cutting machine, and vacuum-adsorbing the wafer through an adsorption mechanism of the laser stealth cutting machine; The wafer after the laser grooving process is subjected to back-side laser transmission invisible dicing corresponding to the dicing road area, so that the wafer is divided into a plurality of core particles.

7. The wafer cutting method according to claim 6, characterized in that: The wafer after the laser grooving process is placed face down in a laser stealth cutting machine, and the wafer is vacuum adsorbed by an adsorption mechanism of the laser stealth cutting machine, including: Placing the wafer after laser grooving with its front side facing downward in a laser stealth cutting machine; The flatness of the wafer is adjusted by the lifting platform of the laser stealth cutting machine, so that the flatness deviation value of the wafer after the flatness adjustment is between 3 μm and 6 μm; The wafer is vacuum adsorbed by the adsorption mechanism of the laser stealth cutting machine.

8. The wafer cutting method according to claim 1, characterized in that: The step of stretching the through-cut film to create a gap between two adjacent core particles in the wafer and performing a material extraction process on the core particles includes: Performing a degumming treatment on the through-cut membrane; Performing wafer expansion processing on the debonded wafer to generate a gap between two adjacent core particles, wherein the gap between the two adjacent core particles is between 10 μm and 100 μm; A single die is taken from the wafer after the wafer expansion process.

9. The wafer cutting method according to claim 8, characterized in that: The debonding treatment of the through-cut film comprises: The through-cut film is irradiated with ultraviolet rays to release the adhesion between the through-cut film and the wafer.

10. The wafer cutting method according to claim 9, characterized in that: The through-cut film is a UV adhesive film.

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