Silicon carbide wafer slicing process

Abstract

The present invention relates to the technical field of silicon carbide wafer slicing, and specifically to a silicon carbide wafer slicing process. The present invention comprises the following steps: S1, taking a silicon carbide ingot with a thickness of 4-6 cm, using invisible laser cutting at the center position of the silicon carbide ingot to form two silicon carbide crystal columns with a thickness of 2-3 cm, then separating the two silicon carbide crystal columns to obtain two silicon carbide crystal columns with the same thickness, and cutting the silicon carbide ingot in half by using laser invisible cutting to obtain 256 silicon carbide slices with the same thickness. Not only can no loss be generated when the silicon carbide ingot is cut into silicon carbide crystal columns, but only loss is generated when the silicon carbide slices are finally polished, the loss generated by slicing can be reduced, and more silicon carbide slices can be obtained. Moreover, all the silicon carbide slices obtained by cutting and peeling can be uniformly ground and polished, effectively simplifying the processing technology and improving production efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon carbide wafer slicing, and in particular to a silicon carbide wafer slicing process. Background Art

[0002] Silicon carbide wafers, also known as silicon carbide single crystal sheets, are sheet-shaped single crystal materials obtained by cutting, grinding, and polishing silicon carbide crystals along a specific crystal direction.

[0003] Since the slicing loss of silicon carbide wafers is large when using multi-wire cutting and laser stripping technology, 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.

[0004] In the prior art, when slicing silicon carbide wafers, since the silicon carbide ingot needs to be cut into multiple silicon carbide crystal columns by laser cutting, unnecessary losses will be generated in the process of cutting into crystal columns. Moreover, 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. Summary of the Invention

[0005] The object of the present invention is to provide a silicon carbide wafer slicing process to solve the problems raised in the above background technology.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A silicon carbide wafer slicing process comprises the following steps:

[0008] S1. Take a 4-6 cm thick silicon carbide ingot and use invisible laser cutting at the center of the silicon carbide ingot to form two 2-3 cm thick silicon carbide crystal columns. Then separate the two silicon carbide crystal columns to obtain two silicon carbide crystal columns of uniform thickness.

[0009] S2. All the silicon carbide crystal columns obtained in step S1 are used as new silicon carbide crystal ingots, and step S1 is repeated until the thickness of the obtained silicon carbide crystal columns is D, 300≤D≤500μm;

[0010] S3. Using a laser to cut the silicon carbide crystal column with a thickness of D obtained in step S2 at the center of the silicon carbide crystal ingot to form two silicon carbide thin slices with the same thickness. Finally, a glass carrier is bonded to the surfaces of the two silicon carbide thin slices using an adhesive.

[0011] S4, heating the silicon carbide thin slice obtained in step S3 from the surface of one of the glass carriers, then rapidly cooling it, and finally using a suction cup to absorb the upper glass carrier to separate the two silicon carbide thin slices to form two independent silicon carbide thin slices of different thicknesses;

[0012] S5. Grind and polish the cross sections of all the silicon carbide slices obtained in step S4 to form silicon carbide slices with flat surfaces on both sides.

[0013] Preferably, in step S1, invisible laser cutting forms equidistant damage at the center of the silicon carbide ingot, thereby forming a modified layer with broken molecular bonds inside the silicon carbide column, so that the connection of the silicon carbide ingot becomes fragile and easy to separate.

[0014] Preferably, in step S1, when separating the two silicon carbide crystal columns, firstly, heating is performed by contact with a heat medium, and then rapid cooling is performed by contact with a coolant, so as to break the silicon carbide crystal ingot and form two silicon carbide crystal columns of uniform thickness.

[0015] Preferably, in step S3, the process of bonding glass carriers to the surfaces of two silicon carbide thin slices by adhesive is as follows: first, adhesive is applied to the surface of the silicon carbide wafer, a glass carrier is bonded to the adhesive-coated surface of the silicon carbide wafer, and then the silicon carbide wafer and the glass carrier are flipped over, adhesive is applied to the other side of the silicon carbide wafer, and another glass carrier is bonded by adhesive to achieve bonding of glass carriers on both sides of the silicon carbide thin slice.

[0016] Preferably, in step S5, the polishing process for the silicon carbide slice with a cross section is as follows: polishing the cross section of the silicon carbide wafer, then debonding the glass carrier, and removing the adhesive to obtain a silicon carbide slice with smooth surfaces on both sides.

[0017] Preferably, in step S5, the polishing process for the silicon carbide slice with cross sections on both sides is: first polish the cross section of one side of the silicon carbide wafer, apply adhesive on the polished surface and bond it to a glass carrier after polishing, then flip the silicon carbide wafer, debond the glass carrier on the unpolished side and remove the adhesive, then polish the cross section of the other side, debond the glass carrier after polishing and remove the adhesive to obtain a silicon carbide slice with smooth surfaces on both sides.

[0018] Preferably, in step S5, the loss generated when grinding the silicon carbide slice is ≥15 μm.

[0019] Beneficial effects of the present invention:

[0020] By cutting the silicon carbide ingot in half using laser invisible cutting, 256 silicon carbide slices of uniform thickness can be obtained. This not only eliminates the loss when the silicon carbide ingot is cut into silicon carbide crystal columns, but only produces loss when the silicon carbide slices are finally polished. This can reduce the loss caused by slicing and obtain more silicon carbide slices. In addition, all the silicon carbide slices obtained by cutting and peeling can be uniformly ground and polished, effectively simplifying the processing technology and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0022] Figure 1 It is a schematic flow chart of step S1 of the present invention;

[0023] Figure 2 It is a schematic flow chart of step S2 of the present invention;

[0024] Figure 3 It is a schematic flow chart of step S3 of the present invention;

[0025] Figure 4 It is a schematic flow chart of step S4 of the present invention;

[0026] Figure 5 1 is a schematic diagram of the process of polishing a silicon carbide slice having a cross section on one side in step S5 of the present invention;

[0027] Figure 6 It is a schematic diagram of the process of grinding a silicon carbide slice with cross sections on both sides in step S5 of the present invention.

[0028] The reference numerals in the figures are as follows:

[0029] 1. Silicon carbide ingot, 2. Silicon carbide column, 3. Silicon carbide wafer, 4. Adhesive, 5. Glass carrier, 6. Suction cup. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0031] Example 1

[0032] S1. Take a 4cm thick silicon carbide ingot and use invisible laser cutting at the center of the silicon carbide ingot to form two 2cm thick silicon carbide crystal columns. Then separate the two silicon carbide crystal columns to obtain two silicon carbide crystal columns of uniform thickness.

[0033] S2. Cut two 2-cm-thick silicon carbide crystal columns using the process in step S1 to obtain four 1-cm-thick silicon carbide crystal columns.

[0034] Four silicon carbide crystal pillars with a thickness of 1 cm are cut using the process in step S1 to obtain eight silicon carbide crystal pillars with a thickness of 5000 μm;

[0035] Cutting eight silicon carbide crystal pillars with a thickness of 5000 μm using the process in step S1 to obtain sixteen silicon carbide crystal pillars with a thickness of 2500 μm;

[0036] Sixteen silicon carbide crystal columns with a thickness of 2500 μm are cut using the process in step S1 to obtain thirty-two silicon carbide crystal columns with a thickness of 1250 μm;

[0037] Thirty-two silicon carbide crystal pillars with a thickness of 1250 μm are cut using the process in step S1 to obtain sixty-four silicon carbide crystal pillars with a thickness of 625 μm;

[0038] Sixty-four silicon carbide crystal columns with a thickness of 625 μm were cut using the process in step S1 to obtain one hundred and twenty-eight silicon carbide crystal columns with a thickness of 312.5 μm.

[0039] S3. The 312.5 μm thick silicon carbide crystal column obtained in step S2 is cut at the center of the silicon carbide crystal ingot using invisible laser cutting to form two 156.25 μm thick silicon carbide slices. Finally, a glass carrier is bonded to the surfaces of the two silicon carbide slices using an adhesive.

[0040] S4. The silicon carbide thin slices obtained in step S3 are heated from the surface of one of the glass carriers, and then rapidly cooled. Finally, a suction cup is used to absorb the upper glass carrier to separate the two silicon carbide thin slices to form two independent silicon carbide thin slices with a thickness of 156.25 μm. In step S2, a total of 128 silicon carbide crystal pillars with a thickness of 312.5 μm are obtained. After steps S3 and S4, 256 silicon carbide thin slices with a thickness of 156.25 μm are obtained.

[0041] S5. Grind and polish the cross-sections of all the silicon carbide slices obtained in step S4. For a silicon carbide slice with only one side being a cross-section, 56.25 μm is ground off from one side to obtain a silicon carbide slice with a thickness of 100 μm. For a silicon carbide slice with both sides being a cross-section, 25 μm is ground off from one side and 31.25 μm is ground off from the other side to obtain a silicon carbide slice with a thickness of 100 μm. The 256 silicon carbide slices with a thickness of 156.25 μm obtained in step S4 are ground into a total of 256 silicon carbide slices with a thickness of 100 μm.

[0042] Example 2

[0043] S1. Take a 5cm thick silicon carbide ingot and use invisible laser cutting at the center of the silicon carbide ingot to form two 2.5cm thick silicon carbide crystal columns. Then separate the two silicon carbide crystal columns to obtain two silicon carbide crystal columns of uniform thickness.

[0044] S2. Cut two 2.5 cm thick silicon carbide crystal columns using the process in step S1 to obtain four 1.25 cm thick silicon carbide crystal columns;

[0045] Four silicon carbide crystal pillars with a thickness of 1.25 cm are cut using the process in step S1 to obtain eight silicon carbide crystal pillars with a thickness of 6250 μm;

[0046] Cutting eight silicon carbide crystal pillars with a thickness of 6250 μm using the process in step S1 to obtain sixteen silicon carbide crystal pillars with a thickness of 3125 μm;

[0047] Sixteen silicon carbide crystal pillars with a thickness of 3125 μm are cut using the process in step S1 to obtain thirty-two silicon carbide crystal pillars with a thickness of 1562.2 μm;

[0048] Thirty-two silicon carbide crystal pillars with a thickness of 1562.5 μm are cut using the process in step S1 to obtain sixty-four silicon carbide crystal pillars with a thickness of 781.25 μm;

[0049] Sixty-four silicon carbide crystal columns with a thickness of 781.25 μm were cut using the process in step S1 to obtain one hundred and twenty-eight silicon carbide crystal columns with a thickness of 390.625 μm.

[0050] S3. Using a laser to cut the 390.625 μm thick silicon carbide crystal column obtained in step S2 at the center of the silicon carbide crystal ingot to form two 195.3125 μm thick silicon carbide slices. Finally, a glass carrier is bonded to the surfaces of the two silicon carbide slices using an adhesive.

[0051] S4. The silicon carbide thin slices obtained in step S3 are heated from the surface of one of the glass carriers, and then rapidly cooled. Finally, a suction cup is used to absorb the upper glass carrier to separate the two silicon carbide thin slices to form two independent silicon carbide thin slices with a thickness of 195.3125 μm. In step S2, a total of 128 silicon carbide crystal pillars with a thickness of 390.625 μm are obtained. After steps S3 and S4, 256 silicon carbide thin slices with a thickness of 195.3125 μm are obtained.

[0052] S5. Grind and polish the cross-sections of all the silicon carbide slices obtained in step S4. For a silicon carbide slice with only one side being a cross-section, 45.3125 μm is ground off from one side to obtain a silicon carbide slice with a thickness of 150 μm. For a silicon carbide slice with both sides being a cross-section, 25 μm is ground off from one side and 25.3125 μm is ground off from the other side to obtain a silicon carbide slice with a thickness of 150 μm. The 256 silicon carbide slices with a thickness of 195.3125 μm obtained in step S4 are ground into a total of 256 silicon carbide slices with a thickness of 150 μm.

[0053] Example 3

[0054] S1. Take a 6 cm thick silicon carbide ingot and use invisible laser cutting at the center of the silicon carbide ingot to form two 3 cm thick silicon carbide crystal columns. Then separate the two silicon carbide crystal columns to obtain two silicon carbide crystal columns of uniform thickness.

[0055] S2. Cut two 3 cm thick silicon carbide crystal columns using the process in step S1 to obtain four 1.5 cm thick silicon carbide crystal columns;

[0056] Four silicon carbide crystal pillars with a thickness of 1.5 cm are cut using the process in step S1 to obtain eight silicon carbide crystal pillars with a thickness of 7500 μm;

[0057] Cutting eight silicon carbide crystal pillars with a thickness of 7500 μm using the process in step S1 to obtain sixteen silicon carbide crystal pillars with a thickness of 3750 μm;

[0058] Sixteen silicon carbide crystal pillars with a thickness of 3750 μm are cut using the process in step S1 to obtain thirty-two silicon carbide crystal pillars with a thickness of 1875 μm;

[0059] Thirty-two silicon carbide crystal pillars with a thickness of 1875 μm are cut using the process in step S1 to obtain sixty-four silicon carbide crystal pillars with a thickness of 937.5 μm;

[0060] Sixty-four silicon carbide crystal columns with a thickness of 937.5 μm were cut using the process in step S1 to obtain one hundred and twenty-eight silicon carbide crystal columns with a thickness of 468.75 μm.

[0061] S3. Using a laser to cut the 468.75 μm thick silicon carbide crystal column obtained in step S2 at the center of the silicon carbide crystal ingot to form two 234.375 μm thick silicon carbide slices. Finally, a glass carrier is bonded to the surfaces of the two silicon carbide slices using an adhesive.

[0062] S4. The silicon carbide thin slices obtained in step S3 are heated from the surface of one of the glass carriers, and then rapidly cooled. Finally, a suction cup is used to absorb the upper glass carrier to separate the two silicon carbide thin slices to form two independent silicon carbide thin slices with a thickness of 234.375 μm. In step S2, a total of 128 silicon carbide crystal pillars with a thickness of 468.75 μm are obtained. After steps S3 and S4, 256 silicon carbide thin slices with a thickness of 234.375 μm are obtained.

[0063] S5. Grind and polish the cross-sections of all the silicon carbide slices obtained in step S4. For a silicon carbide slice with only one side being a cross-section, 34.375 μm is ground off from one side to obtain a silicon carbide slice with a thickness of 200 μm. For a silicon carbide slice with both sides being a cross-section, 15 μm is ground off from one side and 19.375 μm is ground off from the other side to obtain a silicon carbide slice with a thickness of 200 μm. The 256 silicon carbide slices with a thickness of 234.375 μm obtained in step S4 are ground into a total of 256 silicon carbide slices with a thickness of 200 μm.

[0064] For the 100 μm silicon carbide wafers prepared in Examples 1-4, for ease of comparison, the data of all Examples were normalized based on the data of Example 1 to obtain the following Table 1.

[0065] Table 1

[0066]

[0067] As shown in Table 1, for the cutting of 4-6 cm silicon carbide ingots, different silicon carbide ingots can be selected for cutting according to the different requirements for the thickness of silicon carbide slices, and finally 256 silicon carbide slices of the same thickness are obtained.

[0068] Compared with related technologies, the silicon carbide wafer slicing process provided by the present invention has the following beneficial effects:

[0069] By cutting the silicon carbide ingot in half using laser invisible cutting, 256 silicon carbide slices of uniform thickness can be obtained. This not only avoids loss when the silicon carbide ingot is cut into silicon carbide crystal columns, but only causes loss when the silicon carbide slices are finally polished. This can reduce the loss caused by slicing and obtain more silicon carbide slices. Moreover, all the silicon carbide slices obtained by cutting and peeling can be uniformly ground and polished, effectively simplifying the processing technology and improving production efficiency.

[0070] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A silicon carbide wafer slicing process, characterized in that: The following steps are involved: S1. Take a 4-6 cm thick silicon carbide ingot and use invisible laser cutting at the center of the silicon carbide ingot to form two 2-3 cm thick silicon carbide crystal columns. Then separate the two silicon carbide crystal columns to obtain two silicon carbide crystal columns of uniform thickness. S2. All the silicon carbide crystal columns obtained in step S1 are used as new silicon carbide crystal ingots, and step S1 is repeated until the thickness of the obtained silicon carbide crystal columns is D, 300≤D≤500μm; S3. Using a laser to cut the silicon carbide crystal column with a thickness of D obtained in step S2 at the center of the silicon carbide crystal ingot to form two silicon carbide thin slices of the same thickness. Finally, glass carriers are bonded to both sides of the silicon carbide thin slices using an adhesive. S4, heating the silicon carbide thin slice obtained in step S3 from the surface of one of the glass carriers, then rapidly cooling it, and finally using a suction cup to absorb the upper glass carrier to separate the two silicon carbide thin slices to form two independent silicon carbide thin slices of different thicknesses; S5, grinding and polishing the cross sections of all the silicon carbide slices obtained in step S4 to form silicon carbide slices with flat surfaces on both sides; In step S1, the invisible laser cutting forms equidistant damage at the center of the silicon carbide ingot, thereby forming a modified layer with broken molecular bonds inside the silicon carbide column, so that the connection of the silicon carbide ingot becomes fragile and easy to separate; In step S1, when separating the two silicon carbide crystal columns, firstly, heating is performed by contact with a heat medium, and then rapidly cooling is performed by contact with a coolant, so as to separate the silicon carbide crystal ingot and form two silicon carbide crystal columns of uniform thickness; In step S3, the process of bonding glass carriers to the surfaces of two silicon carbide wafers by adhesive is as follows: first, adhesive is applied to the surface of the silicon carbide wafer, a glass carrier is bonded to the adhesive-coated surface of the silicon carbide wafer, then the silicon carbide wafer and the glass carrier are flipped over, adhesive is applied to the other side of the silicon carbide wafer, and another glass carrier is bonded by adhesive to achieve bonding of glass carriers on both sides of the silicon carbide wafer.

2. A silicon carbide wafer slicing process according to claim 1, characterized in that: In step S5, the polishing process for the silicon carbide slice with a cross section is as follows: polishing the cross section of the silicon carbide wafer, then debonding the glass carrier, and removing the adhesive to obtain a silicon carbide slice with smooth surfaces on both sides.

3. A silicon carbide wafer slicing process according to claim 2, characterized in that: In step S5, the polishing process for the silicon carbide slice with cross sections on both sides is as follows: first, the cross section of one side of the silicon carbide wafer is polished, and after polishing, an adhesive is applied to the polished surface and bonded to a glass carrier, and then the silicon carbide wafer is flipped over, the glass carrier on the unpolished side is debonded and the adhesive is removed, and then the cross section of the other side is polished, and after polishing, the glass carrier is debonded and the adhesive is removed to obtain a silicon carbide slice with smooth surfaces on both sides.

4. A silicon carbide wafer slicing process according to claim 3, characterized in that: In step S5 , the loss generated when grinding the silicon carbide slice is ≥15 μm.

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