Laser cutting method and equipment based on silicon carbide wafer

Abstract

The invention discloses a laser cutting method and device based on a silicon carbide wafer. The method comprises the steps that S100, the silicon carbide wafer with the back face facing upwards and attached with a cutting film is placed on a gluing cleaning platform, and the back face of the whole wafer is evenly coated with glue; s200, the silicon carbide wafer is placed on a transparent suction cup of a laser surface cutting platform to generate a first cutting path; s300, first laser is focused on the metal layer on the back face of the silicon carbide wafer, and the metal layer on the back face of the wafer is completely removed along the first cutting path to form a V groove; s400, the silicon carbide wafer is subjected to film pasting again to generate a second cutting path; and S500, second laser is focused in the silicon carbide wafer, laser modification cutting is carried out in each cutting channel along the second cutting path, and a chopper is used for pressing the cutting channels downwards to achieve separation of the chips. According to the method, the cutting effects of different lasers are utilized, and the phenomena of back metal tearing, front side edge breakage and poor straightness in an existing cutting means are avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor processing, and more specifically, relates to a laser cutting method and equipment based on silicon carbide wafers. Background Art

[0002] Silicon carbide wafers, also known as silicon carbide single crystal sheets, are single crystal materials obtained by cutting, grinding, and polishing silicon carbide crystals along a specific crystallization direction. Laser cutting uses a focused high-power density laser beam to irradiate the workpiece, causing the irradiated material to quickly melt, vaporize, ablate, or reach the ignition point, while using a high-speed airflow coaxial with the beam to blow away the molten material, thereby achieving the cutting of the workpiece. Since the use of multi-wire cutting and laser stripping technology to slice silicon carbide wafers has a large loss, the existing technology uses laser cutting to cut the silicon carbide ingot into multiple silicon carbide crystal columns, and then slices the silicon carbide crystal columns one by one. In the prior art, when slicing silicon carbide wafers, since the silicon carbide ingot needs to be cut into multiple silicon carbide crystal columns through laser cutting, unnecessary losses will be generated in the process of cutting into crystal columns. In addition, when slicing one by one, each slicing requires a bonding and debonding of the glass carrier, as well as high temperature and then cooling for separation during separation. This results in large losses when slicing silicon carbide wafers, a small number of slices obtained, a complex process, and high processing costs.

[0003] In order to solve the above problems, patent document CN115555732A discloses a method for cutting silicon carbide wafers, which converges parallel laser beams into conical laser beams, uses the tip of the conical laser beam to focus on the inside of the silicon carbide wafer for modification and cutting, and then splits it into silicon carbide wafer blocks by expanding the thin film on the outer surface of the silicon carbide wafer. However, this method still has two problems. First, the silicon carbide wafer mentioned in the patent should be a structureless silicon carbide bare chip. Since the silicon carbide wafer has a high thermal conductivity and hardness, it is actually impossible to achieve effective separation by laser modification and cutting and using the film expansion method. It must be separated by mechanical external force. Second, for silicon carbide wafers with a metal layer on the back, this method cannot solve the problems of tearing and adhesion of the metal layer after cutting. Therefore, the present invention can effectively solve the above problems and achieve high-quality separation of silicon carbide wafers.

[0004] In addition, the special document CN116038143A discloses a silicon carbide wafer cutting process, which uses plasma to cut the wafer surface to form a cutting path; uses laser to perform invisible cutting on the bottom of the cutting path to destroy the metal deposition on the bottom of the cutting path and the wafer; fits the wafer to the cutting mold frame, cuts off the blockage, removes the carrier; and breaks the cutting path partially by expanding the film to achieve wafer cutting. After the cutting path is formed by plasma cutting, the surface roughness of the cutting path is relatively large. When laser invisible cutting is used, the laser cannot be focused inside the wafer, so effective invisible cutting cannot be achieved. At the same time, this method changes the process of depositing metal coating on the front surface. Summary of the invention

[0005] In order to solve the current problems of tearing of the back metal layer, chipping of the front edge and poor straightness after laser cutting of silicon carbide wafers, the present invention provides a laser cutting method and equipment based on silicon carbide wafers, which adopt ultraviolet laser and infrared laser to cut the back metal layer and the front non-metallic layer of the silicon carbide wafer respectively, and utilize the cutting effects of different lasers to solve the problems of back metal tearing, front edge chipping and poor straightness occurring in the current cutting methods.

[0006] To achieve the above object, according to a first aspect of the present invention, a laser cutting method based on a silicon carbide wafer is provided, comprising:

[0007] S100: Place the silicon carbide wafer with the back side facing up and the dicing film attached on the glue coating and cleaning platform, then drop water-soluble glue on the center of the back side of the wafer, and evenly coat the entire back side of the wafer with the glue by rotating the platform;

[0008] S200: After the glue is air-dried, the silicon carbide wafer is placed on a transparent suction cup of the laser surface cutting platform, and the first CCD visual imaging is used to identify and locate the front cutting path position of the silicon carbide wafer, and a first cutting path is generated;

[0009] S300: focusing a first laser on the metal layer on the back side of the silicon carbide wafer, and adjusting the repetition rate, power, and platform scanning speed process parameters of the laser along the first cutting path to completely remove the metal layer on the back side of the wafer to form a V-groove;

[0010] S400: After the cutting is completed, the silicon carbide wafer is placed on the glue coating and cleaning platform, the water-soluble glue is rinsed with pure water, and the silicon carbide wafer is re-laminated to ensure that the front side faces upward. The silicon carbide wafer is placed on the microporous ceramic suction cup of the laser hidden cutting platform, and the second CCD visual imaging is used to identify and locate the front cutting path of the silicon carbide wafer, and the second cutting path is generated;

[0011] S500: The second laser is focused inside the silicon carbide wafer. Along the second cutting path, the laser repetition rate, power, platform scanning speed, cutting times and other process parameters are regulated. Laser modified cutting is performed in each cutting path, and a protective film is covered on the front side of the cut silicon carbide wafer. A splitter is pressed down on the cutting path to separate the chips one by one.

[0012] Furthermore, the front side of the silicon carbide wafer is a structural layer, and a partial area within the cutting path is covered with a metal layer.

[0013] Furthermore, the back side of the silicon carbide wafer is fully covered with a metal layer with a thickness less than or equal to 5 μm.

[0014] Furthermore, in step S100, the silicon carbide wafer is supported by an iron ring and attached to the dicing film.

[0015] Furthermore, in step S100, the rotation speed of the glue coating and cleaning platform is 100r / min-3000r / min.

[0016] Furthermore, in step S100, the capacity of the glue is determined according to the size of the silicon carbide wafer and the viscosity of the glue, and is 5ml-15ml.

[0017] Furthermore, in step S300, the depth of the V-groove should be smaller than the thickness of the metal layer on the back side of the silicon carbide wafer, and the width should be smaller than the width of the cutting path.

[0018] Furthermore, in step S300, the first laser is an ultraviolet laser with a wavelength of 355nm, and a power fluctuation range is less than 0.1W.

[0019] Furthermore, in step S500, the second laser is an infrared laser with a wavelength of 1064nm, and a power fluctuation range is less than 0.01W.

[0020] Furthermore, the cutting position deviation of the first laser and the second laser on the silicon carbide wafer does not exceed ±5 μm.

[0021] Furthermore, in step S500, the width of the cutting road is not less than 20 μm.

[0022] Furthermore, the blade width of the riving knife is not greater than 20 μm.

[0023] According to a second aspect of the present invention, there is provided a laser cutting device based on a silicon carbide wafer, comprising:

[0024] The film-sticking and gluing mechanism is used to place the silicon carbide wafer with the back side facing upward and the dicing film attached on the gluing and cleaning platform, then drop water-soluble glue on the center of the back side of the wafer, and evenly apply the glue to the entire back side of the wafer by rotating the platform;

[0025] A first cutting path planning mechanism is used to place the silicon carbide wafer on a transparent suction cup of the laser surface cutting platform, identify and locate the front cutting path position of the silicon carbide wafer by using the first CCD visual imaging, and generate a first cutting path;

[0026] A first cutting mechanism is used to emit a first laser and focus on the metal layer on the back side of the silicon carbide wafer, and along the first cutting path, adjust the repetition rate, power and platform scanning speed process parameters of the laser to completely remove the metal layer on the back side of the wafer to form a V-groove;

[0027] The second cutting path planning mechanism is used to place the silicon carbide wafer on the glue coating and cleaning platform, rinse the water-soluble glue with pure water, re-laminate the silicon carbide wafer to ensure that the front side faces upward, place the silicon carbide wafer on the microporous ceramic suction cup of the laser hidden cutting platform, use the second CCD visual imaging to identify and locate the front cutting path position of the silicon carbide wafer, and generate the second cutting path;

[0028] And a second cutting mechanism is used to emit a second laser focused on the inside of the silicon carbide wafer, and along the second cutting path, adjust the laser's repetition rate, power, platform scanning speed, cutting times and other process parameters, perform laser modified cutting in each cutting path, and cover the front side of the cut silicon carbide wafer with a protective film, and use a splitter to press down on the cutting path to separate the chips one by one.

[0029] Furthermore, the film-sticking and gluing mechanism comprises a gluing and cleaning platform suction cup, an iron ring, a cutting film and a gluing head;

[0030] The front cutting path of the silicon carbide wafer faces downward and the metal layer on the back faces upward. The cutting film is attached to the iron ring. The silicon carbide wafer with the film attached is adsorbed on the glue coating and cleaning platform suction cup by negative pressure. The glue coating head is moved to the center of the silicon carbide wafer. After dripping water-soluble glue, the glue coating and cleaning platform suction cup is rotated to ensure that the glue is evenly coated on the surface of the silicon carbide wafer.

[0031] Furthermore, the first cutting path planning mechanism includes a transparent suction cup and a first CCD, the silicon carbide wafer is adsorbed on the transparent suction cup by negative pressure, and the position of the cutting path on the wafer is identified by the first CCD to generate a first cutting path.

[0032] Furthermore, the first cutting mechanism includes a first laser and a laser surface cutting platform.

[0033] Furthermore, the second cutting path planning mechanism includes a cleaning head, a microporous ceramic suction cup, a second CCD and a laser hidden cutting platform.

[0034] Furthermore, the second cutting mechanism includes a second laser, a cleaver, a supporting platform and a protective film.

[0035] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0036] 1. The method of the present invention adopts ultraviolet laser and infrared laser to cut the back metal layer and the front non-metal layer of the silicon carbide wafer respectively, and utilizes the cutting effects of different lasers to solve the problems of back metal tearing, front edge collapse and poor straightness in current cutting methods.

[0037] 2. The method of the present invention focuses the first laser on the metal layer on the back side of the silicon carbide wafer, and along the first cutting path, adjusts the laser's repetition rate, power and platform scanning speed process parameters to form a V-groove, thereby achieving cutting of the metal layer on the back side of the silicon carbide wafer.

[0038] 3. The method of the present invention focuses the second laser on the inside of the silicon carbide wafer, and regulates the laser's repetition rate, power, platform scanning speed, number of cutting times and other process parameters along the second cutting path, performs laser modified cutting in each cutting path, and covers the front side of the cut silicon carbide wafer with a protective film, and uses a splitter to press down on the cutting path to achieve cutting of the non-metallic layer on the front side of the silicon carbide wafer.

[0039] 4. The equipment of the present invention can improve the technical indicators such as edge collapse and straightness of silicon carbide wafers after cutting, avoid the tearing of the back metal layer, and improve the product yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic flow chart of a laser cutting method based on a silicon carbide wafer according to an embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of the principle of the film-sticking and gluing mechanism in Example 1 of the present invention;

[0042] Figure 3 This is a schematic diagram of the principle of the first cutting mechanism in Example 1 of the present invention;

[0043] Figure 4 This is a schematic diagram of the principle of the second cutting mechanism in Example 1 of the present invention;

[0044] Figure 5 This is a schematic diagram of the cutting process of the second cutting mechanism in Example 1 of the present invention;

[0045] Figure 6 This is a schematic diagram of the principle of the second cutting mechanism in Example 2 of the present invention.

[0046] In all the drawings, the same figure marks represent the same technical features, specifically: 1-glue coating and cleaning platform suction cup, 2-iron ring, 3-cutting film, 4-silicon carbide wafer, 5-water-soluble glue, 6-cutting lane, 7-glue coating head, 8-cleaning head, 9-transparent suction cup, 10-first CCD, 11-first laser, 12-laser surface cutting platform, 13-microporous ceramic suction cup, 14-second laser, 15-second CCD, 16-laser hidden cutting platform, 17-splitting knife, 18-support platform, 19-protective film. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0048] like Figure 1 As shown, the present invention provides a laser cutting method based on silicon carbide wafer, including: firstly, placing a silicon carbide wafer with the back side facing upward and the cutting film pasted on it on a glue coating and cleaning platform, then dripping water-soluble glue on the center of the back side of the wafer, and evenly coating the glue on the entire back side of the wafer by rotating the platform; after the glue is air-dried, placing the silicon carbide wafer on the transparent suction cup of the laser surface cutting platform, using the first CCD visual imaging to identify and locate the position of the front cutting path of the silicon carbide wafer, and generating a cutting path; using an ultraviolet laser to focus on the metal layer on the back side of the silicon carbide wafer, along the preset cutting path, regulating the repetition frequency, power and platform scanning speed of the ultraviolet laser and other process parameters, completely removing the back metal layer to form a V-groove. After the cutting is completed, the silicon carbide wafer is placed on the glue coating and cleaning platform, the water-soluble glue is rinsed clean with pure water, and the silicon carbide wafer is re-filmed to ensure that the front side faces upward. Then place the silicon carbide wafer on the microporous ceramic suction cup of the laser hidden cutting platform, use the second CCD visual imaging to identify and locate the front cutting path of the silicon carbide wafer, and generate a cutting path. Use an infrared laser to focus on the inside of the silicon carbide wafer, and along the preset cutting path, adjust the repetition rate, power of the infrared laser, and the platform scanning speed, cutting times and other process parameters, and perform laser modification cutting in each cutting path; finally, cover the front of the cut silicon carbide wafer with a protective film, and use a splitter to press down on the cutting path to separate the chips one by one. The method of the present invention uses ultraviolet laser and infrared laser to cut the back metal layer and the front non-metal layer of the silicon carbide wafer respectively, and uses the cutting effect of different lasers to solve the problems of back gold tearing, front edge collapse, and poor straightness in the current cutting methods.

[0049] In an embodiment of the present invention, the front side of the silicon carbide wafer is a structural layer, a small amount of metal is covered in the cutting path, and the back side is a fully covered metal layer with a thickness of less than 5 μm. The film is pasted on the silicon carbide wafer on the cutting film and supported by an iron ring. The maximum speed of the glue coating and cleaning platform is 100r / min-3000r / min. The transparent suction cup is a quartz transparent suction cup. The first CCD stably images after passing through the suction cup and the film. The width of the cutting path on the structural surface of the silicon carbide device is not less than 20μm; the first laser is an ultraviolet laser with a wavelength of 355nm, and the power fluctuation range is less than 0.1W; the second laser is an infrared laser with a wavelength of 1064nm, and the power fluctuation range is less than 0.01W; the width of the V-groove cannot be greater than the width of the cutting path, and the depth cannot exceed the thickness of the metal; the cutting position deviation of the first laser and the second laser on the silicon carbide wafer does not exceed ±5μm; the power stability of the infrared laser is high, and the power fluctuation range is less than 0.01W; the blade width of the splitting knife is not higher than 20μm. The method of the present invention focuses a first laser on the metal layer on the back of the silicon carbide wafer, and along the first cutting path, adjusts the laser repetition rate, power and platform scanning speed process parameters to form a V-groove, thereby realizing the cutting of the metal layer on the back of the silicon carbide wafer. Focusing a second laser on the inside of the silicon carbide wafer, along the second cutting path, adjusts the laser repetition rate, power and platform scanning speed, cutting times and other process parameters, performs laser modified cutting in each cutting path, and covers the front of the cut silicon carbide wafer with a protective film, and uses a splitter to press down on the cutting path, thereby realizing the cutting of the non-metallic layer on the front of the silicon carbide wafer.

[0050] Example 1

[0051] In one embodiment of the present invention, a laser cutting method based on silicon carbide wafer is provided. The basic principle of the laser cutting device is as follows: Figure 2-Figure 5 As shown, it includes a glue coating and cleaning platform suction cup (1), an iron ring (2), a cutting film (3), a silicon carbide wafer (4), a water-soluble glue (5), a cutting path (6), a glue coating head (7), a cleaning head (8), a transparent suction cup (9), a first CCD (10), a first laser (11), a laser surface cutting platform (12), a microporous ceramic suction cup (13), a second laser (14), a second CCD (15), a laser hidden cutting platform (16), a splitting knife (17), a supporting platform (18), and a protective film (19).

[0052] The front cutting path (6) of the silicon carbide wafer (4) faces downward and the back metal layer faces upward. The cutting film (3) is attached to the iron ring (2). The silicon carbide wafer (4) with the film attached is adsorbed on the glue coating and cleaning platform suction cup (1) by negative pressure. The glue coating head (7) is moved to the center of the silicon carbide wafer (4). After dripping water-soluble glue (5), the glue coating and cleaning platform suction cup (1) is rotated to ensure that the glue is evenly coated on the surface of the silicon carbide wafer. The silicon carbide wafer (4) coated with water-soluble glue (5) is adsorbed on the transparent suction cup (9) by negative pressure. The first CCD (10) is used to identify the position of the cutting path (6) on the wafer to generate a cutting path, and the first laser (11) of the laser surface cutting platform (12) is controlled to focus on the metal layer on the back of the wafer. The laser surface cutting platform (12) drives the wafer adsorbed by the transparent suction cup (9) to reciprocate, thereby removing the metal layer on the back of the wafer and forming a V groove. The silicon carbide wafer after laser surface cutting is placed on the glue coating cleaning platform suction cup (1), the suction cup is rotated and the cleaning head (8) is moved, and the water-soluble glue is washed away by spraying water mist; the cleaned silicon carbide wafer (4) is re-filmed, ensuring that the front cutting line (6) faces upward and the back metal layer faces downward; the silicon carbide wafer (4) with the cutting film (3) is adsorbed on the microporous ceramic suction cup (13) of the laser hidden cutting platform (16) by negative pressure, and the second CCD (15) is used to identify the position of the cutting line (6) of the wafer. A cutting path is generated, a second laser (14) of a laser hidden cutting platform (16) is controlled to focus on the inside of a wafer, and the wafer adsorbed by a microporous ceramic suction cup (13) is driven by the laser hidden cutting platform (16) to perform reciprocating motion, thereby forming a modified layer inside the wafer; a protective film (19) is covered on the surface of the silicon carbide wafer (4) that has completed laser surface cutting and laser hidden cutting, and the wafer is placed on a supporting platform (18); a splitting knife (17) is moved to align with the position of the cutting path (6), and the splitting knife is pressed downward to split the wafer, thereby realizing the separation of crystal grains of the silicon carbide wafer (4).

[0053] Furthermore, the front side of the silicon carbide wafer 4 is a structural layer, a small amount of metal is covered in the cutting path, and the back side is a fully covered metal layer with a thickness of less than 5 μm;

[0054] Furthermore, the volume of glue dripped by the glue coating head 7 can be selected from 5ml, 10ml, 15ml, etc., depending on the wafer size and glue viscosity;

[0055] Furthermore, the rotation speed of the glue coating and cleaning platform can be a parameter ratio of first a low speed of 100r / min and then a high speed of 2000r / min, the glue is air-dried, and the maximum rotation speed of the platform is 3000r / min;

[0056] Furthermore, the transparent suction cup is a quartz transparent suction cup, and the first CCD forms a stable image after passing through the suction cup and the film;

[0057] Furthermore, the depth of the V-groove should be less than the thickness of the metal layer on the back side of the silicon carbide wafer 4, and the width should be less than the width of the cutting path 6;

[0058] Furthermore, the first laser 11 is an ultraviolet laser with a wavelength of 355 nm, and a power fluctuation range is less than 0.1 W;

[0059] Furthermore, the water mist sprayed by the cleaning head 8 is a two-fluid composed of compressed air and pure water;

[0060] Furthermore, the width of the cutting road on the silicon carbide device structure surface is not less than 20 μm;

[0061] Furthermore, the cutting position deviation of the first laser 11 and the second laser 14 on the silicon carbide wafer 4 may not exceed ±5 μm;

[0062] Furthermore, the red second laser 14 has a wavelength of 1064nm, and a power fluctuation range of less than 0.01W;

[0063] Furthermore, the support platform 18 needs to be located on both sides of the downward pressing position of the riving knife 17;

[0064] Furthermore, the blade width of the riving knife 17 is not greater than 20 μm.

[0065] Example 2

[0066] In another embodiment of the present invention, a laser cutting method based on silicon carbide wafer is provided, wherein the device is as follows: Figure 6 As shown, it includes a glue coating and cleaning platform suction cup (1), an iron ring (2), a cutting film (3), a silicon carbide wafer (4), a water-soluble glue (5), a cutting path (6), a glue coating head (7), a cleaning head (8), a transparent suction cup (9), a first CCD (10), a first laser (11), a laser surface cutting platform (12), a microporous ceramic suction cup (13), a second laser (14), a second CCD (15), a laser hidden cutting platform (16), a splitting knife (17), a supporting platform (18), and a protective film (19).

[0067] The front cutting path (6) of the silicon carbide wafer (4) faces downward and the back metal layer faces upward. The cutting film (3) is attached to the iron ring (2). The silicon carbide wafer (4) with the film attached is adsorbed on the glue coating and cleaning platform suction cup (1) by negative pressure. The glue coating head (7) is moved to the center of the silicon carbide wafer (4). After dripping water-soluble glue (5), the glue coating and cleaning platform suction cup (1) is rotated to ensure that the glue is evenly coated on the surface of the silicon carbide wafer. The silicon carbide wafer (4) coated with water-soluble glue (5) is adsorbed on the transparent suction cup (9) by negative pressure. The first CCD (10) is used to identify the position of the cutting path (6) on the wafer to generate a cutting path, and the first laser (11) of the laser surface cutting platform (12) is controlled to focus on the metal layer on the back of the wafer. The laser surface cutting platform (12) drives the wafer adsorbed by the transparent suction cup (9) to reciprocate, thereby removing the metal layer on the back of the wafer and forming a V groove. The silicon carbide wafer after laser surface cutting is placed on the glue coating cleaning platform suction cup (1), the suction cup is rotated and the cleaning head (8) is moved, and the water-soluble glue is washed off by spraying water mist; the cleaned silicon carbide wafer (4) is re-filmed to ensure that the front cutting path (6) faces upward and the back metal layer faces downward; the silicon carbide wafer (4) with the cutting film (3) is adsorbed on the microporous ceramic suction cup (13) of the laser hidden cutting platform (16) by negative pressure, and the second CCD (15) is used to identify the position of the wafer's cutting path (6), generate a cutting path, and control the laser hidden cutting platform (16) to move the silicon carbide wafer (4) to the microporous ceramic suction cup (13) of the laser hidden cutting platform (16). The second laser (14) of the laser cutting machine (6) is focused on the inside of the wafer, and the wafer adsorbed by the microporous ceramic suction cup (13) is driven to move back and forth through the laser hidden cutting platform (16), so as to form a modified layer inside the wafer; the silicon carbide wafer (4) that has completed laser surface cutting and laser hidden cutting is re-laminated to ensure that the front cutting path (6) faces downward and the back metal layer faces upward, and a protective film (19) is covered on the surface of the wafer, and then the wafer is placed on the supporting platform (18); the splitting knife (17) is moved to align with the cutting path (6) position, and the splitting knife is pressed down to split the wafer, so as to separate the grains of the silicon carbide wafer (4).

[0068] Furthermore, the front side of the silicon carbide wafer 4 is a structural layer, a small amount of metal is covered in the cutting path, and the back side is a fully covered metal layer with a thickness of less than 5 μm;

[0069] Furthermore, the volume of glue dripped by the glue coating head 7 can be selected from 5ml, 10ml, 15ml, etc. according to the wafer size and glue viscosity;

[0070] Furthermore, the rotation speed of the glue coating and cleaning platform can be a parameter ratio of first a low speed of 100r / min and then a high speed of 2000r / min, the glue is air-dried, and the maximum rotation speed of the platform is 3000r / min;

[0071] Furthermore, the transparent suction cup is a quartz transparent suction cup, and the first CCD forms a stable image after passing through the suction cup and the film;

[0072] Furthermore, the depth of the V-groove should be less than the thickness of the metal layer on the back side of the silicon carbide wafer 4, and the width should be less than the width of the cutting path 6;

[0073] Furthermore, the first laser 11 is an ultraviolet laser with a wavelength of 355 nm, and a power fluctuation range is less than 0.1 W;

[0074] Furthermore, the water mist sprayed by the cleaning head 8 is a two-fluid composed of compressed air and pure water;

[0075] Furthermore, the width of the cutting road on the silicon carbide device structure surface is not less than 20 μm;

[0076] Furthermore, the cutting position deviation of the first laser 11 and the second laser 14 on the silicon carbide wafer 4 may not exceed ±5 μm;

[0077] Furthermore, the red second laser 14 has a wavelength of 1064nm, and a power fluctuation range of less than 0.01W;

[0078] Furthermore, the support platform 18 needs to be located on both sides of the downward pressing position of the riving knife 17;

[0079] Furthermore, the blade width of the riving knife 17 is not greater than 20 μm.

[0080] The device of the present invention can improve the technical indicators such as edge collapse and straightness of silicon carbide wafers after cutting, avoid the tearing phenomenon of the back metal layer, and improve the product yield.

[0081] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A laser cutting method based on silicon carbide wafer, characterized in that: include: S100: Place the silicon carbide wafer with the back side facing up and the dicing film attached on the glue coating and cleaning platform, then drop water-soluble glue on the center of the back side of the wafer, and evenly coat the entire back side of the wafer with the glue by rotating the platform; S200: After the glue is air-dried, the silicon carbide wafer is placed on a transparent suction cup of the laser surface cutting platform, and the first CCD visual imaging is used to identify and locate the front cutting path position of the silicon carbide wafer, and a first cutting path is generated; S300: focusing a first laser on the metal layer on the back side of the silicon carbide wafer, and adjusting the repetition rate, power, and platform scanning speed process parameters of the laser along the first cutting path to completely remove the metal layer on the back side of the wafer to form a V-groove; S400: After the cutting is completed, the silicon carbide wafer is placed on the glue coating and cleaning platform, the water-soluble glue is rinsed with pure water, and the silicon carbide wafer is re-laminated to ensure that the front side faces upward. The silicon carbide wafer is placed on the microporous ceramic suction cup of the laser hidden cutting platform, and the second CCD visual imaging is used to identify and locate the front cutting path of the silicon carbide wafer, and the second cutting path is generated; S500: The second laser is focused inside the silicon carbide wafer. Along the second cutting path, the laser repetition rate, power, platform scanning speed, cutting times and other process parameters are regulated. Laser modified cutting is performed in each cutting path, and a protective film is covered on the front side of the cut silicon carbide wafer. A splitter is pressed down on the cutting path to separate the chips one by one.

2. A laser cutting method based on silicon carbide wafer according to claim 1, characterized in that: The front side of the silicon carbide wafer is a structural layer, and a part of the area within the cutting path is covered with a metal layer.

3. A laser cutting method based on silicon carbide wafer according to claim 2, characterized in that: The back side of the silicon carbide wafer is fully covered with a metal layer with a thickness less than or equal to 5 μm.

4. A laser cutting method based on silicon carbide wafer according to any one of claims 1 to 3, characterized in that: In step S100, the silicon carbide wafer is supported by an iron ring and attached to a dicing film.

5. The laser cutting method based on silicon carbide wafer according to claim 4, characterized in that: In step S100, the rotation speed of the glue coating and cleaning platform is 100r / min-3000r / min.

6. The laser cutting method based on silicon carbide wafer according to claim 5, characterized in that: In step S100, the volume of the glue is determined according to the size of the silicon carbide wafer and the viscosity of the glue, and is 5ml-15ml.

7. A laser cutting method based on silicon carbide wafer according to any one of claims 1 to 3, characterized in that: In step S300, the depth of the V-groove should be smaller than the thickness of the metal layer on the back side of the silicon carbide wafer, and the width should be smaller than the width of the cutting path.

8. The laser cutting method based on silicon carbide wafer according to claim 7, characterized in that: In step S300, the first laser is an ultraviolet laser with a wavelength of 355nm, and a power fluctuation range is less than 0.1W.

9. The laser cutting method based on silicon carbide wafer according to claim 8, characterized in that: In step S500, the second laser is an ultraviolet laser with a wavelength of 1064nm, and a power fluctuation range is less than 0.01W.

10. The laser cutting method based on silicon carbide wafer according to claim 9, characterized in that: The cutting position deviation of the first laser and the second laser on the silicon carbide wafer does not exceed ±5μm.

11. A laser cutting method based on silicon carbide wafer according to any one of claims 1 to 3, characterized in that: In step S500, the width of the cutting road is not less than 20 μm.

12. A laser cutting method based on silicon carbide wafer according to claim 11, characterized in that: The blade width of the riving knife is not greater than 20 μm.

13. A laser cutting device based on silicon carbide wafer, characterized in that: include: The film-sticking and gluing mechanism is used to place the silicon carbide wafer with the back side facing upward and the dicing film attached on the gluing and cleaning platform, then drop water-soluble glue on the center of the back side of the wafer, and evenly apply the glue to the entire back side of the wafer by rotating the platform; A first cutting path planning mechanism is used to place the silicon carbide wafer on a transparent suction cup of the laser surface cutting platform, identify and locate the front cutting path position of the silicon carbide wafer by using the first CCD visual imaging, and generate a first cutting path; A first cutting mechanism is used to emit a first laser and focus on the metal layer on the back side of the silicon carbide wafer, and along the first cutting path, adjust the repetition rate, power and platform scanning speed process parameters of the laser to completely remove the metal layer on the back side of the wafer to form a V-groove; The second cutting path planning mechanism is used to place the silicon carbide wafer on the glue coating and cleaning platform, rinse the water-soluble glue with pure water, re-laminate the silicon carbide wafer to ensure that the front side faces upward, place the silicon carbide wafer on the microporous ceramic suction cup of the laser hidden cutting platform, use the second CCD visual imaging to identify and locate the front cutting path position of the silicon carbide wafer, and generate the second cutting path; And a second cutting mechanism is used to emit a second laser focused on the inside of the silicon carbide wafer, and along the second cutting path, adjust the laser's repetition rate, power, platform scanning speed, cutting times and other process parameters, perform laser modified cutting in each cutting path, and cover the front side of the cut silicon carbide wafer with a protective film, and use a splitter to press down on the cutting path to separate the chips one by one.

14. The laser cutting device based on silicon carbide wafer according to claim 13, characterized in that: The film-sticking and gluing mechanism comprises a gluing and cleaning platform suction cup (1), an iron ring (2), a cutting film (3) and a gluing head (7); The front cutting path (6) of the silicon carbide wafer (4) faces downward and the metal layer on the back faces upward. The cutting film (3) is attached to the iron ring (2). The silicon carbide wafer (4) with the film attached is adsorbed on the glue coating and cleaning platform suction cup (1) by negative pressure. The glue coating head (7) is moved to the center of the silicon carbide wafer (4). After dripping water-soluble glue (5), the glue coating and cleaning platform suction cup (1) is rotated to ensure that the glue is evenly coated on the surface of the silicon carbide wafer.

15. The laser cutting device based on silicon carbide wafer according to claim 14, characterized in that: The first cutting path planning mechanism comprises a transparent suction cup (9) and a first CCD (10); the silicon carbide wafer (4) is adsorbed on the transparent suction cup (9) by negative pressure; the position of the cutting path (6) on the wafer is identified by the first CCD (10) to generate a first cutting path.

16. The laser cutting device based on silicon carbide wafer according to claim 15, characterized in that: The first cutting mechanism comprises a first laser (11) and a laser surface cutting platform (12).

17. The laser cutting device based on silicon carbide wafer according to claim 16, characterized in that: The second cutting path planning mechanism comprises a cleaning head (8), a microporous ceramic suction cup (13), a second CCD (15) and a laser stealth cutting platform (16).

18. The laser cutting device based on silicon carbide wafer according to claim 17, characterized in that: The second cutting mechanism comprises a second laser (14), a splitting knife (17), a supporting platform (18) and a protective film (19).

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