Chip dicing method and dicing structure

Abstract

This invention provides a chip cutting method and structure. The method includes a laser cutting step, a first blade cutting step, and a second blade cutting step performed sequentially. On one hand, laser cutting can remove some or all of the metal material beforehand, reducing or eliminating the generation of metal chips during subsequent blade cutting operations, thereby reducing the load during blade cutting and minimizing defects such as chipping, cracking, and peeling. On the other hand, the width of the laser cutting area is smaller than the width of the first blade cutting area, allowing the subsequent first blade cutting process to cover the laser cutting marks, effectively removing residual marks on the sidewalls of the laser-cut groove. This results in a groove and sidewalls with pure blade cutting in the final structure, eliminating sidewall sintering introduced by laser cutting. Furthermore, compared to pure laser cutting, this invention uses a combination of laser cutting and blade cutting to reduce the thermal impact of laser cutting, effectively preventing a decrease in chip strength.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor technology and relates to a chip cutting method and cutting structure. Background Technology

[0002] Wafer dicing is an unavoidable step in the chip manufacturing process. Before chip packaging, the prepared wafer needs to be divided into individual chip dies according to a predetermined size. Currently, there are two main methods for chip dicing:

[0003] (1) Mechanical cutting, which uses a diamond blade rotating at high speed to cut the wafer through the dicing channel to obtain the chip. Pure blade cutting is the most commonly used cutting method in the chip cutting field. Its advantage is that it is simple and convenient to operate. However, as the thickness of the chip metal layer continues to increase and the pattern structure becomes more complex, blade cutting has also exposed corresponding disadvantages. For example, in CMOS image sensor (CIS) chips, the thickness of the low dielectric constant (LowK) layer is constantly increasing. The metal debris generated during cutting is easily wrapped around the diamond blade, reducing the cutting ability and causing serious edge chipping and side cracks. In addition, the metal debris constantly thrown out during blade cutting will fall on the wafer surface, causing chip surface damage and reducing the final yield of the entire process.

[0004] (2) Laser cutting is a high-precision, non-contact chip cutting method. It utilizes continuous, constant-amplitude pulse waves emitted by a laser generator to ablate and vaporize the metal in the cutting path, thereby achieving chip separation. The advantage of laser cutting is that it is non-contact with the chip surface, and no mechanical stress is introduced during the cutting process, which can effectively avoid defects such as chipping, cracking, and peeling that occur with blade cutting. However, the disadvantage of laser cutting is the thermal impact zone (HAZ) on the chip during the ablation process, which can lead to weakened chip strength and internal defects. In addition, CIS chips have high surface cleanliness requirements, and molten particles may be generated on the chip sidewalls during laser ablation. These molten particles may fall onto the chip surface during the packaging process, causing failure.

[0005] Therefore, how to improve chip cutting methods to reduce mechanical damage to chips and reduce or eliminate the adverse effects of laser cutting has become an important technical problem that needs to be solved by those skilled in the art.

[0006] It should be noted that the above introduction to the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of this application and facilitating understanding by those skilled in the art. It should not be assumed that these technical solutions are known to those skilled in the art simply because they have been described in the background section of this application. Summary of the Invention

[0007] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a chip cutting method and cutting structure to solve the problems that existing cutting methods are prone to mechanical damage or thermal effects and easily contaminate the chip, causing failure.

[0008] To achieve the above and other related objectives, the present invention provides a chip dicing method, comprising the following steps:

[0009] A substrate to be cut is provided, the substrate to be cut includes a first surface and a second surface disposed opposite to each other, the substrate to be cut defines a cutting track area, a laser cutting area, a first blade cutting area and a second blade cutting area, the first blade cutting area is disposed in the cutting track area and the width of the first blade cutting area is smaller than the width of the cutting track area, the laser cutting area is disposed in the first blade cutting area and the width of the laser cutting area is smaller than the width of the first blade cutting area, the second blade cutting area is disposed in the laser cutting area and the width of the second blade cutting area is smaller than the width of the laser cutting area;

[0010] The substrate to be cut is laser-cut to form a laser cutting groove in the laser cutting area. The laser cutting groove opens from the first surface and extends toward the second surface. The depth of the laser cutting groove is less than the thickness of the substrate to be cut.

[0011] A first blade is provided, the width of which is equal to the width of the first blade cutting area. The edge of the first blade is aligned with the edge of the first blade cutting area, and the substrate to be cut is mechanically cut from the first surface to obtain a first blade cutting groove in the first blade cutting area. The depth of the first blade cutting groove is less than the thickness of the substrate to be cut and greater than the depth of the laser cutting groove.

[0012] A second blade is provided, the width of which is equal to the width of the cutting area of ​​the second blade. The edge of the second blade is aligned with the edge of the cutting area of ​​the second blade. The substrate to be cut is mechanically cut from the bottom of the first blade cutting groove to obtain a second blade cutting groove in the cutting area of ​​the second blade. The second blade cutting groove penetrates the second surface.

[0013] Optionally, the substrate to be cut includes a base layer and a metal interconnect layer sequentially disposed on the second surface in a direction pointing from the first surface, and the laser cutting groove extends at least into the metal interconnect layer.

[0014] Optionally, the laser cutting groove extends into the substrate layer.

[0015] Optionally, the substrate to be cut includes a first substrate and a second substrate sequentially disposed and bonded to each other in a direction from the second surface to the first surface. The first substrate includes a first base layer and a first metal interconnect layer sequentially disposed in a direction from the second surface to the first surface. The second substrate includes a second metal interconnect layer and a second base layer sequentially disposed in a direction from the second surface to the first surface. The laser cutting groove penetrates the second base layer and extends at least into the second metal interconnect layer.

[0016] Optionally, the laser-cut groove extends into the first metal interconnect layer or the first substrate layer; and / or, the thickness of the second substrate layer is less than the thickness of the first substrate layer.

[0017] Optionally, the substrate to be cut has a test structure in the cutting channel area, the test structure including at least one metal layer, and the laser cutting groove penetrates at least one of the metal layers.

[0018] Optionally, the laser-cut groove extends through all the metal layers of the test structure.

[0019] Optionally, the boundary of the test structure does not exceed the laser-cut area.

[0020] Optionally, the substrate to be cut includes a plurality of CIS chips, and the cutting channel region is provided between two adjacent CIS chips. The CIS chip includes a device structure region and a sealing ring structure region located around the device structure region, or it may also include a virtual structure region located around the sealing ring structure region. The sealing ring structure region is provided with a metal sealing ring structure, and the virtual structure region is provided with a virtual metal structure. The distance between the side of the virtual metal structure facing the nearest cutting channel region and the edge of the nearest cutting channel region is greater than 0.

[0021] Optionally, the distance between the plane containing the bottom surface of the laser cutting groove and the plane containing the bottom surface of the first blade cutting groove is D1, and the distance between the plane containing the bottom surface of the laser cutting groove and the second surface is D2, wherein the range of D1 / D2 is 1 / 3 to 1 / 2; and / or, the width between the sidewalls of the first blade cutting groove and the sidewalls of the same side of the laser cutting groove is 5 micrometers to 15 micrometers.

[0022] Optionally, the centerline of the first blade cutting groove coincides with the centerline of the laser cutting groove.

[0023] This invention provides a cutting structure, comprising:

[0024] A substrate to be cut includes a first surface and a second surface disposed opposite to each other. The substrate to be cut defines a cutting track area, a laser cutting area, a first blade cutting area, and a second blade cutting area. The first blade cutting area is disposed within the cutting track area and the width of the first blade cutting area is smaller than the width of the cutting track area. The laser cutting area is disposed within the first blade cutting area and the width of the laser cutting area is smaller than the width of the first blade cutting area. The second blade cutting area is disposed within the laser cutting area and the width of the second blade cutting area is smaller than the width of the laser cutting area.

[0025] A laser cutting groove is located in the laser cutting area. The laser cutting groove opens from the first surface and extends toward the second surface. The depth of the laser cutting groove is less than the thickness of the substrate to be cut.

[0026] Optionally, the substrate to be cut includes a base layer and a metal interconnect layer sequentially disposed on the second surface in a direction pointing from the first surface, and the laser cutting groove extends at least into the metal interconnect layer.

[0027] Optionally, the substrate to be cut includes a first substrate and a second substrate sequentially disposed and bonded to each other in a direction from the second surface to the first surface. The first substrate includes a first base layer and a first metal interconnect layer sequentially disposed in a direction from the second surface to the first surface. The second substrate includes a second metal interconnect layer and a second base layer sequentially disposed in a direction from the second surface to the first surface. The laser cutting groove penetrates the second base layer and extends at least into the second metal interconnect layer.

[0028] Optionally, the substrate to be cut has a test structure in the cutting channel area, the test structure including at least one metal layer, and the laser cutting groove penetrates at least one of the metal layers.

[0029] As described above, the chip cutting method of the present invention includes a laser cutting step, a first blade cutting step, and a second blade cutting step performed sequentially. On the one hand, laser cutting can remove some or all of the metal material in advance, reducing or eliminating the generation of metal chips during subsequent blade cutting operations, thereby reducing the load during blade cutting and reducing defects such as chipping / cracks / peeling caused by blade cutting. On the other hand, the width of the laser cutting area is smaller than the width of the first blade cutting area, allowing the subsequent first blade cutting process to cover the laser cutting traces, effectively removing residual traces on the sidewall of the laser cutting groove, thus obtaining a groove and sidewall with pure blade cutting in the final structure, eliminating sidewall sintering introduced by laser cutting. In addition, compared with pure laser cutting, the present invention uses a combination of laser cutting and blade cutting to reduce the thermal impact of laser cutting, effectively avoiding a reduction in chip strength. Because the cutting structure of the present invention has a laser cutting groove, the metal material in the cutting area is minimized, which is beneficial to reducing mechanical damage caused by subsequent blade cutting. Furthermore, because a first blade cutting area with a width greater than the laser cutting area is defined, it is also beneficial to eliminate the adverse effects introduced by laser cutting, effectively improving the yield of the cutting process. Attached Figure Description

[0030] Figure 1 The diagram shown is a process flow chart of the chip dicing method of the present invention.

[0031] Figure 2 The diagram shown is a schematic representation of the structure of a substrate to be cut provided in one embodiment of the chip cutting method of the present invention.

[0032] Figure 3 The diagram shown is a schematic representation of the structure of a substrate to be cut provided in another embodiment of the chip cutting method of the present invention.

[0033] Figure 4 The diagram shows a schematic of a chip cutting method of the present invention in one embodiment, in which a laser generator emits continuous constant amplitude pulse waves to ablate the material in the laser cutting area.

[0034] Figure 5 The diagram shows a schematic of the structure obtained after forming a laser cutting groove in one embodiment of the chip cutting method of the present invention.

[0035] Figure 6 The diagram shows a blade cutting process in one embodiment of the chip cutting method of the present invention.

[0036] Figure 7 The diagram shows a comparison between the width of the first blade and the width of the laser cutting groove in one embodiment of the chip cutting method of the present invention.

[0037] Figure 8The diagram shown is a schematic diagram of the structure obtained after forming the first blade cutting groove in one embodiment of the chip cutting method of the present invention.

[0038] Figure 9 The diagram shown is a schematic representation of the structure obtained after forming the second blade cutting groove in one embodiment of the chip cutting method of the present invention.

[0039] Figure 10 This is a comparison chart showing the width of the first blade, the width of the second blade, and the width of the laser cutting groove used in a pair of proportions.

[0040] Figure 11 Displayed as in Figure 10 The diagram shown is a schematic of the structure obtained after cutting the discrete chips in the comparative example.

[0041] Figure 12 This diagram shows the relative positions of the first and second blades used in a comparative example of pure blade cutting with the substrate to be cut.

[0042] Figure 13 The diagram shows the structure obtained after two blade cuts to obtain discrete chips.

[0043] Figure 14 This appears to be a chipping defect.

[0044] Figure 15 This appears to be a peeling defect.

[0045] Figure 16 This appears to be a void defect.

[0046] Figure 17 This appears to be a peeling defect.

[0047] Figure 18 The image shown is a topographic view of the chip sidewall using the chip dicing method of the present invention.

[0048] Figure 19 This image shows the morphology of the chip sidewall as cut using a pure blade cutting method.

[0049] Figure 20 The diagram shown is a schematic representation of the cutting structure of the present invention in one embodiment.

[0050] Explanation of reference numerals in the attached figures

[0051] Steps S1 to S4 100 substrates to be cut

[0052] 101 First Surface

[0053] 102 Second Surface

[0054] 103 Basal layer

[0055] 104 Metal interconnect layer

[0056] 1041 Dielectric Layer

[0057] 1042 Metal Wiring Layer

[0058] 105 First substrate

[0059] 1051 First basal layer

[0060] 1052 First Metal Interconnect Layer

[0061] 106 Second substrate

[0062] 1061 Second Metal Interconnect Layer

[0063] 1062 Second basal layer

[0064] 107 Test Structure

[0065] 108 Metal Sealing Ring Structure

[0066] 109 Virtual Metal Structure

[0067] 110, 110a laser cutting groove

[0068] 111 First blade cutting groove

[0069] 112 Second blade cutting groove

[0070] 200 laser generator

[0071] 300, 300a, 300b First Blade

[0072] 400, 400a, 400b Second Blade

[0073] A Cutting Channel Area

[0074] B. Laser cutting area

[0075] C. First blade cutting area

[0076] D. Second blade cutting area

[0077] E Device Structure Region

[0078] F Sealing ring structure area

[0079] G Virtual Structure Region Detailed Implementation

[0080] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0081] It should be emphasized that the term "including / comprises" as used herein refers to the presence of a feature, whole, step, or component, but does not exclude the presence or addition of one or more other features, wholes, steps, or components.

[0082] Features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0083] In the detailed description of embodiments of the present invention, for ease of explanation, the schematic diagrams illustrating the device structure may be partially enlarged without adhering to the general scale, and the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. Furthermore, in actual manufacturing, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0084] For ease of description, spatial relation terms such as “below,” “under,” “lower than,” “below,” “above,” and “upper” may be used herein to describe the relationship between one element or feature shown in the accompanying drawings and other elements or features. It will be understood that these spatial relation terms are intended to include directions other than those depicted in the drawings for devices in use or operation. Furthermore, when a layer is referred to as being “between” two layers, it may be the only layer between the two layers, or there may be one or more layers in between.

[0085] In the context of this application, the structure described above the first feature may include embodiments in which the first and second features are in direct contact, or embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0086] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0087] This invention provides a chip cutting method; please refer to [link / reference]. Figure 1 The diagram shows the process flow of this method, which includes the following steps:

[0088] S1: A substrate to be cut is provided. The substrate to be cut includes a first surface and a second surface disposed opposite to each other. The substrate to be cut defines a cutting track area, a laser cutting area, a first blade cutting area, and a second blade cutting area. The first blade cutting area is disposed in the cutting track area and the width of the first blade cutting area is smaller than the width of the cutting track area. The laser cutting area is disposed in the first blade cutting area and the width of the laser cutting area is smaller than the width of the first blade cutting area. The second blade cutting area is disposed in the laser cutting area and the width of the second blade cutting area is smaller than the width of the laser cutting area.

[0089] S2: The substrate to be cut is laser-cut to form a laser cutting groove in the laser cutting area. The laser cutting groove opens from the first surface and extends toward the second surface. The depth of the laser cutting groove is less than the thickness of the substrate to be cut.

[0090] S3: Provide a first blade, the width of which is equal to the width of the first blade cutting area, align the edge of the first blade with the edge of the first blade cutting area, and mechanically cut the substrate to be cut from the first surface to obtain a first blade cutting groove in the first blade cutting area. The depth of the first blade cutting groove is less than the thickness of the substrate to be cut and greater than the depth of the laser cutting groove.

[0091] S4: Provide a second blade, the width of which is equal to the width of the cutting area of ​​the second blade. Align the edge of the second blade with the edge of the cutting area of ​​the second blade. Perform mechanical cutting on the substrate to be cut from the bottom of the first blade cutting groove to obtain a second blade cutting groove in the cutting area of ​​the second blade. The second blade cutting groove penetrates the second surface.

[0092] The following section details each of the above steps in conjunction with the structural diagram.

[0093] Please refer to the following first. Figure 2The following steps are performed: A substrate 100 to be cut is provided. The substrate 100 includes a first surface 101 and a second surface 102 disposed opposite to each other. The substrate to be cut defines a cutting track region A, a laser cutting region B, a first blade cutting region C, and a second blade cutting region D. The first blade cutting region C is disposed within the cutting track region A and the width of the first blade cutting region C is smaller than the width of the cutting track region A. The laser cutting region B is disposed within the first blade cutting region C and the width of the laser cutting region B is smaller than the width of the first blade cutting region C. The second blade cutting region D is disposed within the laser cutting region B and the width of the second blade cutting region D is smaller than the width of the laser cutting region B.

[0094] Specifically, the cutting area A serves as the cutting area, wherein the laser cutting area B is used to form a laser cutting groove, the first blade cutting area C is used to form a first blade cutting groove, and the second blade cutting area D is used to form a second blade cutting groove, which will be described in detail in subsequent steps.

[0095] As an example, in Figure 2 In the illustrated embodiment, the substrate 100 to be cut includes a base layer 103 and a metal interconnect layer 104 sequentially disposed in the direction from the second surface 102 to the first surface 101. The laser cutting groove formed subsequently will extend at least into the metal interconnect layer 104. For example, in a preferred embodiment, the laser cutting groove will extend into the base layer 103, thereby minimizing the amount of metal that the blade needs to remove during the subsequent first blade cutting operation, thereby reducing the generation of metal chips during the blade cutting process, reducing the load on the first blade during the cutting process, and achieving the effect of reducing the occurrence of damage during blade cutting and improving the cutting process yield.

[0096] As an example, the substrate 103 may include a silicon substrate, a germanium substrate, a germanium-silicon substrate, a silicon carbide substrate, a III-V compound substrate (such as gallium nitride, gallium arsenide, etc.), or a composite substrate such as silicon-on-insulator (SOI), germanium-on-insulator (GOI), germanium-silicon-on-insulator. The substrate 103 may be doped or undoped, and may contain doped regions of various concentrations or electrical types to achieve different functions. The required electronic components may be fabricated in the substrate 103. The types and configurations of materials of the substrate 103 are not limited to the examples listed above.

[0097] As an example, the metal interconnect layer 104 may include a dielectric layer 1041 and at least one metal wiring layer 1042 embedded in the dielectric layer 1041. When the metal interconnect layer 104 includes multiple layers of the metal wiring layer 1042, adjacent metal wiring layers 1042 can be electrically connected through metal vias (not shown). The dielectric layer 1041 may be made of silicon oxide, a low-k dielectric, or other suitable materials. The low-k dielectric may be, for example, fluorine-doped silicon oxide, carbon-doped silicon oxide, etc. The material of the metal wiring layer 1042 or the metal via may be, for example, copper, aluminum, tungsten, titanium, titanium nitride, gold, platinum, etc.

[0098] In other embodiments, the substrate 100 to be cut may also be a multilayer stacked substrate, for example, see [reference needed]. Figure 3 The diagram shows a structural schematic of the substrate 100 to be cut in another embodiment, which employs a double-layer stacked substrate, including a first substrate 105 and a second substrate 106 sequentially disposed and bonded to each other in the direction from the second surface 102 to the first surface 101. It should be noted that... Figure 3 In the example shown, we can continue to use Figure 2 In the example shown, the description of the direction, "the direction in which the second surface 102 points to the first surface 101", is understood to mean the direction in which the lower surface of the substrate 100 to be cut points to the upper surface. The first substrate 105 includes a first base layer 1051 and a first metal interconnect layer 1052 sequentially disposed in the direction in which the second surface 102 points to the first surface 101. The second substrate 106 includes a second metal interconnect layer 1061 and a second base layer 1062 sequentially disposed in the direction in which the second surface 102 points to the first surface 101. The laser cutting groove formed subsequently will penetrate the second base layer 1062 and extend at least into the second metal interconnect layer 1061. For example, in a preferred embodiment, the laser cutting groove will extend into the first metal interconnect layer 1052. In another preferred embodiment, the laser cutting groove will extend into the first base layer 1051.

[0099] As an example, the thickness of the second substrate layer 1062 is less than the thickness of the first substrate layer 1051.

[0100] As an example, the substrate 100 to be cut has a test structure 107 in the cutting channel region A. The test structure 107 includes at least one metal layer, and the subsequently formed laser cutting groove will penetrate at least one of the metal layers. For example, in a preferred embodiment, the laser cutting groove will penetrate all the metal layers of the test structure 107.

[0101] As an example, the boundary of the test structure 105 does not exceed the laser-cut area B.

[0102] As an example, the substrate to be cut includes multiple CIS chips, and the cutting channel region A is provided between two adjacent CIS chips. Figure 3 Taking the illustrated structure as an example, the CIS chip includes a device structure region E and a sealing ring structure region F located around the device structure region E. In a further example, it may also include a virtual structure region G located around the sealing ring structure region F. The sealing ring structure region F is provided with a metal sealing ring structure 108, and the virtual structure region G is provided with a virtual metal structure 109. The distance between the side of the virtual metal structure 109 facing the nearest cutting channel region A and the edge of the nearest cutting channel region A is greater than 0. The virtual metal structure 109 is used to prevent stress during cutting from being transmitted to the device structure region E.

[0103] Please see again Figure 4 and Figure 5 Step S2 is performed: the substrate 100 to be cut is laser-cut to form a laser cutting groove 110 in the laser cutting area B. The laser cutting groove 110 opens from the first surface 102 and extends toward the second surface 102. The depth of the laser cutting groove 110 is less than the thickness of the substrate 100 to be cut. Figure 4 The diagram shows a process of ablation of the material in the laser-cut region B by emitting continuous constant-amplitude pulse waves from a laser generator 200. Figure 5 The diagram shows the material in the laser-cut area B vaporizing after ablation to form the laser-cut groove 110.

[0104] Specifically, the purpose of this laser cutting step is to remove some or all of the metal in the blade cutting area in advance, reduce or eliminate the generation of metal chips during subsequent blade cutting operations, thereby reducing the load during subsequent blade cutting processes, reducing the generation of defects such as chipping / cracks / peeling caused by blade cutting, and reducing or eliminating the problem of metal chips falling on the wafer surface and causing damage to the chip surface.

[0105] Specifically, the depth of the laser cutting groove 110 can be set according to the specific layer structure composition of the substrate 100 to be cut, for example, for... Figure 2 The laser cutting groove 110 of the substrate 100 to be cut shown can extend into the metal interconnect layer 104 to remove part of the metal layer, or it can further extend into the base layer 103 to remove as much metal as possible beforehand, which would otherwise be removed by the blade. For example, for... Figure 3The laser cutting groove 110 of the substrate 100 shown can penetrate the second base layer 1062 and extend into the second metal interconnect layer 1061 to remove part of the metal layer, or it can extend further into the first metal interconnect layer 1052 to remove more metal layers, or it can extend further into the first base layer 1051 to remove as many metal layers as possible.

[0106] Please see again Figures 6 to 8 Step S3 is performed as follows: a first blade 300 is provided, the width of which is equal to the width of the first blade cutting area C. The edge of the first blade 300 is aligned with the edge of the first blade cutting area C, and mechanical cutting is performed on the substrate 100 to be cut from the first surface 101 to obtain a first blade cutting groove 111 in the first blade cutting area C. The depth of the first blade cutting groove 111 is less than the thickness of the substrate 100 to be cut and greater than the depth of the laser cutting groove 110. Figure 6 The diagram shows a blade cutting process. Figure 7 The image shows a comparison between the width of the first blade 300 and the width of the laser cutting groove 110. Figure 8 The diagram shows the structure obtained after cutting the first blade cutting groove 111.

[0107] Specifically, after initially obtaining the laser cutting groove 110, the present invention changes to blade cutting, mainly to reduce the thermal impact (HAZ) of the laser cutting ablation process on the chip, and to prevent the chip strength from weakening and internal defects from increasing due to the thermal impact.

[0108] Specifically, since the metal in the first blade cutting area C has been removed to a certain extent or mostly by the previous laser cutting step, the generation of metal chips will be greatly reduced during the blade cutting process in this step, thereby reducing or eliminating chip yield problems caused by cutting debris splashing, and the blade load can also be reduced, which helps to reduce the generation of defects such as chipping / cracks / peeling caused by blade cutting.

[0109] Specifically, such as Figure 7 As shown, since the width of the laser cutting area B is smaller than the width of the first blade cutting area C, and the width of the first blade 300 is equal to the width of the first blade cutting area C and the edge of the first blade 300 is aligned with the edge of the first blade cutting area C, the first blade 300 can cover the laser cutting groove 110 during the cutting process, thereby effectively removing molten particles that may be generated on the side wall of the laser cutting groove 110 during the laser ablation process.

[0110] As an example, the width between the sidewalls on the same side of the first blade cutting groove 111 and the laser cutting groove 110 ranges from 5 micrometers to 15 micrometers, such as 8 micrometers, 10 micrometers, 12 micrometers, etc.

[0111] In some embodiments, the center line of the first blade cutting groove 111 coincides with the center line of the laser cutting groove 110, that is, when mechanical cutting is performed using the first blade 300, the cutting is concentric with respect to the laser cutting groove 110.

[0112] Specifically, the depth of the first blade cutting groove 111 is less than the thickness of the substrate 100 to be cut but greater than the depth of the laser cutting groove 110. In other words, there will be no trace of the laser cutting groove 110 in the final structure, and a groove shape and sidewalls cut purely by blade can be obtained, eliminating sidewall sintering and other adverse effects introduced by laser cutting. Furthermore, the first blade cutting groove 111 does not completely penetrate the substrate 100 to be cut, which can prepare for the next step of precision cutting, so as to ensure the accuracy and quality of the cutting edge.

[0113] As an example, the distance between the plane containing the bottom surface of the laser cutting groove 110 and the plane containing the bottom surface of the first blade cutting groove 111 is D1, and the distance between the plane containing the bottom surface of the laser cutting groove 110 and the second surface 102 is D2, wherein the range of D1 / D2 is 1 / 3 to 1 / 2.

[0114] Please see again Figure 9 Step S4 is performed: a second blade 400 is provided, the width of the second blade 400 is equal to the width of the second blade cutting area D, the edge of the second blade 400 is aligned with the edge of the second blade cutting area D, and mechanical cutting is performed on the substrate 100 to be cut from the bottom surface of the first blade cutting groove 111 to obtain a second blade cutting groove 112 in the second blade cutting area D, the second blade cutting groove 112 penetrating the second surface 102.

[0115] In some embodiments, the center line of the second blade cutting groove 112 coincides with the center line of the first blade cutting groove 111.

[0116] Thus, discrete chips are obtained through sequential laser cutting, first blade cutting, and second blade cutting steps. Since laser cutting removes some or all of the metal in the blade cutting area beforehand, it improves the cutting capability of subsequent blade cutting and reduces chip surface damage caused by metal debris. Furthermore, using a first blade with a width greater than the laser cutting groove during blade cutting eliminates sidewall sintering and other adverse effects introduced by laser cutting. In other words, the chip cutting method of this invention combines the advantages of both laser cutting and blade cutting while avoiding the problems associated with either method, thereby improving the yield of the cutting process.

[0117] As an example, a pair of proportions is provided; please refer to [link / reference]. Figure 10 and Figure 11 ,in, Figure 10 The diagram shows a comparison of the widths of the first blade 300a, the second blade 400a, and the laser cutting groove 110a used in a pair of proportions. Figure 11 The diagram shows the structure obtained after cutting discrete chips in the above comparative example. In this example, because the width of the laser cutting groove 110a is greater than the width of the first blade 300a, the first blade 300a does not contact the sidewall of the laser cutting groove 110a during the cutting process. The final structure still retains the sidewall of the laser cutting groove 110a, thus molten particles that may be present on the sidewall of the laser cutting groove 110a may fall onto the chip surface during the packaging process, causing failure. However, as... Figure 8 and Figure 9 As shown, in the chip cutting method of the present invention, the first blade 300 can cover the laser cutting groove 110 during the cutting process, thereby effectively removing the molten particles that may be generated on the side wall of the laser cutting groove 110 during the laser ablation process. In the final structure, there will be no trace of the laser cutting groove 110, and a groove shape and side wall cut by pure blade can be obtained, eliminating the side wall sintering and other adverse effects introduced by laser cutting.

[0118] As an example, a comparative example of pure blade cutting is provided; please refer to [link / reference]. Figure 12 and Figure 13 ,in, Figure 12 This diagram shows the relative positions of the first blade 300b, the second blade 400b, and the substrate to be cut in a comparative example of pure blade cutting. Figure 13 The diagram shows the structure obtained after two blade cuts to obtain discrete chips.

[0119] Please see Figures 14 to 17 The above two comparative examples show several defect diagrams resulting from different scenarios. Figure 14This appears to be a chipping defect. Figure 15 This appears to be a peeling defect. Figure 16 This appears to be a void defect. Figure 17 This appears to be a peeling defect.

[0120] According to one embodiment of the present invention, the chip dicing method of the present invention was implemented on a 50-megapixel (50MP) stacked wafer. The results showed that, compared with the pure blade dicing method, the dicing method of the present invention can improve the overall yield by about 1.6% and reduce the introduction of process damage by about 2%.

[0121] Specifically, by observing the sidewall morphology of the chip using optical microscopy (OM) and scanning electron microscopy (SEM), it was found that the chip morphology obtained using the cutting method of this invention showed no laser marks or sintered material adhering to it, and was essentially consistent with the sidewall morphology of pure blade cutting. For example, please refer to... Figure 18 and Figure 19 ,in, Figure 18 The image shown is a topographic view of the chip sidewalls obtained using the chip dicing method of the present invention. Figure 19 The image shows the morphology of the chip sidewall obtained by pure blade cutting, and it can be seen that the two are basically the same.

[0122] Specifically, by collecting the 5S data and three-point bending strength data of the working chips using the chip cutting method of the present invention and comparing them with the data of the pure knife-cut chips, it is found that the 5S data of the working chips is better than that of the pure knife-cut chips, while the chip strength is consistent with that of the pure knife-cut. This result indicates that using a knife width greater than the laser cutting groove width in the present invention can eliminate the adverse effects caused by laser cutting. Among them, 5S refers to a site management method in the field of semiconductor manufacturing and chip production. It originated in Japan and is mainly used to improve and maintain the order and cleanliness of the workplace to improve efficiency and quality. 5S represents the initials of five Japanese words: Seiri (Sorting), Seiton (Straightening), Seiso (Scrubbing), Seiketsu (Standardizing), and Shitsuke (Sustaining). These principles help reduce waste, improve production efficiency and product quality, and create a safer working environment. The three-point bending strength, also known as the flexural strength, refers to the maximum stress that a material can withstand before being bent to fracture. In the chip field, the three-point bending strength is usually used to evaluate the mechanical strength and reliability of chips. During testing, the sample is placed on two support points, and a load is applied in the middle of the two support points to simulate the bending situation that the material may encounter in actual use. For chips, this test helps evaluate their resistance to mechanical stress during manufacturing and use, especially the bending load that may be encountered during packaging and transportation. Through the three-point bending test, the maximum load and fracture strength of the chip material can be determined to ensure the durability and reliability of the chip.

[0123] Specifically, the data of the back corner chipping (back chipping) can be regarded as part of the three-point bending strength data because the back chipping area may be a stress concentration area and is more prone to fracture. By controlling the back chipping, the overall mechanical strength and reliability of the chip can be improved, thus obtaining better performance in the three-point bending test. Back chipping is usually caused by mechanical stress during the cutting process and is related to factors such as the cutting tool, cutting speed, cutting angle, and material hardness. The existence of back chipping may affect the mechanical strength and electrical performance of the chip, especially during packaging and use, which may further deteriorate, resulting in chip fracture or circuit damage.

[0124] As an example, the back chipping situation of a 50MP specification CMOS sensor chip is used to compare the influence of the two cutting methods on the chip strength. Please refer to Table 1 and Table 2. Among them, Table 1 shows the data of the back corner chipping (back chipping) of the pure knife-cut chips, and Table 2 shows the data of the back corner chipping (back chipping) of the chips using the chip cutting method of the present invention.

[0125] Table 1 Back chipping data of pure knife-cut chips

[0126]

[0127] Table 2 Back-collapse data of chips using the chip cutting method of the present invention.

[0128]

[0129]

[0130] As shown in Tables 1 and 2, back collapse was effectively controlled in the three thickness ranges of 30-75 micrometers, 75-100 micrometers, and above 100 micrometers for both pure blade-cut chips and chips cut using the chip cutting method of this invention. No back collapse occurred. However, for pure blade-cut chips, the average back collapse value was 4.53 micrometers and the maximum back collapse value was 25 micrometers, while for chips cut using the chip cutting method of this invention, the average back collapse value was 0.06 micrometers and the maximum back collapse value was 2.5 micrometers. It can be seen that compared with pure blade-cut chips, the average and maximum back collapse values ​​of chips cut using the chip cutting method of this invention are significantly reduced, indicating that the chip cutting method of this invention performs better in controlling back collapse.

[0131] This invention also provides a cutting structure; please refer to [link / reference]. Figure 20 The diagram shows a schematic representation of the cutting structure in one embodiment, including a substrate 100 to be cut and a laser cutting groove 110. The substrate 100 to be cut includes a first surface 101 and a second surface 102 disposed opposite to each other. The substrate to be cut defines a cutting track region A, a laser cutting region B, a first blade cutting region C, and a second blade cutting region D. The first blade cutting region C is disposed within the cutting track region A, and the width of the first blade cutting region C is smaller than the width of the cutting track region A. The laser cutting region B is disposed within the first blade cutting region C, and the width of the laser cutting region B is smaller than the width of the first blade cutting region C. The second blade cutting region D is disposed within the laser cutting region B, and the width of the second blade cutting region D is smaller than the width of the laser cutting region B. The laser cutting groove 110 is located in the laser cutting region B. The laser cutting groove 110 opens from the first surface 102 and extends towards the second surface 102. The depth of the laser cutting groove 110 is smaller than the thickness of the substrate 100 to be cut.

[0132] In some embodiments, the substrate 100 to be cut includes a base layer 103 and a metal interconnect layer 104 sequentially disposed in the direction from the second surface 102 to the first surface 101, and the laser cutting groove 110 extends at least into the metal interconnect layer 104.

[0133] In some embodiments, the substrate to be cut 100 includes a first substrate and a second substrate (not shown) sequentially disposed and bonded to each other in the direction from the second surface 102 to the first surface 101. The first substrate includes a first base layer and a first metal interconnect layer sequentially disposed in the direction from the second surface to the first surface. The second substrate includes a second metal interconnect layer and a second base layer sequentially disposed in the direction from the second surface to the first surface. The laser cutting groove 110 penetrates the second base layer and extends at least into the second metal interconnect layer.

[0134] In some embodiments, the substrate 100 to be cut has a test structure (not shown) in the cutting channel region A, the test structure including at least one metal layer, and the laser cutting groove 110 penetrates at least one of the metal layers.

[0135] In summary, the chip cutting method of the present invention includes a laser cutting step, a first blade cutting step, and a second blade cutting step performed sequentially. On the one hand, laser cutting can remove some or all of the metal material beforehand, reducing or eliminating the generation of metal chips during subsequent blade cutting operations, thereby reducing the load during blade cutting and reducing defects such as chipping, cracking, and peeling caused by blade cutting. On the other hand, the width of the laser cutting area is smaller than the width of the first blade cutting area, allowing the subsequent first blade cutting process to cover the laser cutting traces, effectively removing residual traces on the sidewalls of the laser cutting groove, thus obtaining a pure blade-cut groove and sidewalls in the final structure, eliminating sidewall sintering introduced by laser cutting. Furthermore, compared to pure laser cutting, the present invention uses a combination of laser cutting and blade cutting to reduce the thermal impact of laser cutting, effectively avoiding a decrease in chip strength. Because the cutting structure of the present invention has a laser cutting groove, the metal material in the cutting area is minimized, which helps to reduce mechanical damage caused by subsequent blade cutting. Moreover, because a first blade cutting area wider than the laser cutting area is defined, it also helps to eliminate the adverse effects introduced by laser cutting, effectively improving the yield of the cutting process. Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0136] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A chip cutting method, characterized in that, Includes the following steps: A substrate to be cut is provided, the substrate to be cut includes a first surface and a second surface disposed opposite to each other, the substrate to be cut defines a cutting track area, a laser cutting area, a first blade cutting area and a second blade cutting area, the first blade cutting area is disposed in the cutting track area and the width of the first blade cutting area is smaller than the width of the cutting track area, the laser cutting area is disposed in the first blade cutting area and the width of the laser cutting area is smaller than the width of the first blade cutting area, the second blade cutting area is disposed in the laser cutting area and the width of the second blade cutting area is smaller than the width of the laser cutting area; The substrate to be cut is laser-cut to form a laser cutting groove in the laser cutting area. The laser cutting groove opens from the first surface and extends toward the second surface. The depth of the laser cutting groove is less than the thickness of the substrate to be cut. A first blade is provided, the width of which is equal to the width of the first blade cutting area. The edge of the first blade is aligned with the edge of the first blade cutting area, and the substrate to be cut is mechanically cut from the first surface to obtain a first blade cutting groove in the first blade cutting area. The depth of the first blade cutting groove is less than the thickness of the substrate to be cut and greater than the depth of the laser cutting groove. A second blade is provided, the width of which is equal to the width of the cutting area of ​​the second blade. The edge of the second blade is aligned with the edge of the cutting area of ​​the second blade. The substrate to be cut is mechanically cut from the bottom of the first blade cutting groove to obtain a second blade cutting groove in the cutting area of ​​the second blade. The second blade cutting groove penetrates the second surface.

2. The chip cutting method according to claim 1, characterized in that: The substrate to be cut includes a base layer and a metal interconnect layer sequentially disposed on the second surface in a direction pointing from the first surface, and the laser cutting groove extends at least into the metal interconnect layer.

3. The chip cutting method according to claim 2, characterized in that: The laser cutting groove extends into the substrate layer.

4. The chip cutting method according to claim 1, characterized in that: The substrate to be cut includes a first substrate and a second substrate sequentially disposed and bonded to each other in a direction from the second surface to the first surface. The first substrate includes a first base layer and a first metal interconnect layer sequentially disposed in a direction from the second surface to the first surface. The second substrate includes a second metal interconnect layer and a second base layer sequentially disposed in a direction from the second surface to the first surface. The laser cutting groove penetrates the second base layer and extends at least into the second metal interconnect layer.

5. The chip cutting method according to claim 4, characterized in that: The laser cutting groove extends into the first metal interconnect layer or the first substrate layer; and / or, the thickness of the second substrate layer is less than the thickness of the first substrate layer.

6. The chip cutting method according to claim 1, characterized in that: The substrate to be cut has a test structure in the cutting channel area, the test structure includes at least one metal layer, and the laser cutting groove penetrates at least one of the metal layers.

7. The chip cutting method according to claim 6, characterized in that: The laser-cut groove penetrates all the metal layers of the test structure.

8. The chip cutting method according to claim 6, characterized in that: The boundary of the test structure does not exceed the laser-cut area.

9. The chip cutting method according to claim 1, characterized in that: The substrate to be cut includes multiple CIS chips, and the cutting channel region is provided between two adjacent CIS chips. The CIS chip includes a device structure region and a sealing ring structure region located around the device structure region, or it may also include a virtual structure region located around the sealing ring structure region. The sealing ring structure region is provided with a metal sealing ring structure, and the virtual structure region is provided with a virtual metal structure. The distance between the side of the virtual metal structure facing the nearest cutting channel region and the edge of the nearest cutting channel region is greater than 0.

10. The chip cutting method according to claim 1, characterized in that: The distance between the plane containing the bottom surface of the laser cutting groove and the plane containing the bottom surface of the first blade cutting groove is D1, and the distance between the plane containing the bottom surface of the laser cutting groove and the second surface is D2, wherein the range of D1 / D2 is 1 / 3 to 1 / 2; and / or, the width between the sidewalls of the first blade cutting groove and the sidewalls of the same side of the laser cutting groove is 5 micrometers to 15 micrometers.

11. The chip cutting method according to claim 1, characterized in that: The centerline of the first blade cutting groove coincides with the centerline of the laser cutting groove.

12. A cutting structure, characterized in that, include: A substrate to be cut includes a first surface and a second surface disposed opposite to each other. The substrate to be cut defines a cutting track area, a laser cutting area, a first blade cutting area, and a second blade cutting area. The first blade cutting area is disposed within the cutting track area and the width of the first blade cutting area is smaller than the width of the cutting track area. The laser cutting area is disposed within the first blade cutting area and the width of the laser cutting area is smaller than the width of the first blade cutting area. The second blade cutting area is disposed within the laser cutting area and the width of the second blade cutting area is smaller than the width of the laser cutting area. A laser cutting groove is located in the laser cutting area. The laser cutting groove opens from the first surface and extends toward the second surface. The depth of the laser cutting groove is less than the thickness of the substrate to be cut.

13. The cutting structure according to claim 12, characterized in that: The substrate to be cut includes a base layer and a metal interconnect layer sequentially disposed on the second surface in a direction pointing from the first surface, and the laser cutting groove extends at least into the metal interconnect layer.

14. The cutting structure according to claim 12, characterized in that: The substrate to be cut includes a first substrate and a second substrate sequentially disposed and bonded to each other in a direction from the second surface to the first surface. The first substrate includes a first base layer and a first metal interconnect layer sequentially disposed in a direction from the second surface to the first surface. The second substrate includes a second metal interconnect layer and a second base layer sequentially disposed in a direction from the second surface to the first surface. The laser cutting groove penetrates the second base layer and extends at least into the second metal interconnect layer.

15. The cutting structure according to claim 14, characterized in that: The substrate to be cut has a test structure in the cutting channel area, the test structure includes at least one metal layer, and the laser cutting groove penetrates at least one of the metal layers.

Images