Wafer processing method

Abstract

The invention relates to a wafer processing method which comprises the following steps: providing a wafer of which the front surface is provided with a circuit structure; a carrier is formed on the front face of the wafer, the carrier is made of a paraffin compound, and the density of the paraffin compound is larger than that of paraffin; carrying out thinning processing on the back surface of the wafer on which the carrier is formed so as to reduce the thickness of the wafer; and removing the carrier on the thinned wafer. According to the invention, the wafer can be effectively protected, the product yield is improved, and the process cost is low.

Description

Technical Field

[0001] This application relates to the technical field of solar cell manufacturing, and particularly to a method for wafer processing. Background Art

[0002] Semiconductor thinning process is a key process used to reduce the thickness of wafers during semiconductor manufacturing. This process is usually carried out in the backside processing of wafers. By methods such as mechanical grinding, the backside of the wafer is thinned, thereby reducing the wafer thickness to a suitable thickness for subsequent packaging and applications. Thinning can not only improve the performance of devices, but also improve heat dissipation, reduce the packaging size and lower costs. However, the thinning process may cause damage to the front side of the wafer with circuit patterns, so protective measures must be taken.

[0003] During the backside thinning process of wafers in the semiconductor field, common front side protections usually include coating protection, film protection, and temporary bonding.

[0004] Among them, coating protection is to spin-coat photoresist or polymers, such as polyimide and anti-reflection coatings, on the front side to form a uniform protective layer. However, uneven coating may lead to local protection failure, and organic substances may remain during removal, making it difficult to ensure complete removal of residual organic substances. Film protection is to cover the front side of the wafer with a film to prevent scratching, contamination or chemical corrosion of the circuit patterns. However, the film process is not applicable to thinner wafers, such as wafers with a thickness below 100μm after thinning. The self-stress and warpage of the thinned wafers are relatively large, and there is a high risk of fragmentation. Temporary bonding is to temporarily bond the wafer to a rigid carrier such as glass or silicon wafer to ensure that the wafer remains flat and stable during the thinning process. Although the temporary bonding process is applicable to the thinning of thinner wafers, after the wafer is thinned, the bonding needs to be released and the wafer needs to be cleaned. The process cost is relatively high, and there may be residues or a risk of damaging the front side of the wafer when releasing the bonding. Summary of the Invention

[0005] The embodiments of this application provide a method for wafer processing, which can not only effectively protect the wafer, improve the product yield, but also has a relatively low process cost and a wide application range.

[0006] The method for wafer processing provided by the embodiments of this application includes:

[0007] Providing a wafer, the front side of the wafer having a circuit structure;

[0008] Forming a carrier on the front side of the wafer, the material of the carrier being paraffin composite, and the density of the paraffin composite being greater than the density of paraffin;

[0009] Performing a thinning process on the back side of the wafer formed with the carrier to reduce the thickness of the wafer;

[0010] Remove the carrier from the thinned wafer.

[0011] In some embodiments, a carrier preparation device is used to form a carrier on the front side of the wafer;

[0012] The carrier preparation device includes a tray and a plastic fixing cylinder. The plastic fixing cylinder has a plastic fixing cavity penetrating through the plastic fixing cylinder, and the inner diameter of the plastic fixing cavity is equal to the outer diameter of the wafer;

[0013] The forming of the carrier on the front side of the wafer by using the carrier preparation device includes:

[0014] Place the wafer face up on the tray;

[0015] Place the plastic fixing cylinder on the tray so that the wafer placed on the tray is received in the plastic fixing cavity;

[0016] Inject a liquid paraffin composite into the plastic fixing cavity so that the liquid paraffin composite completely covers the front side of the wafer, and cool the liquid paraffin composite to form the carrier;

[0017] Take out the wafer with the formed carrier from the carrier preparation device.

[0018] In some embodiments, the plastic fixing cylinder is made of an alloy.

[0019] In some embodiments, the thickness of the carrier is 25 μm to 200 μm.

[0020] In some embodiments, the paraffin composite includes paraffin and polyethylene.

[0021] In some embodiments, the paraffin composite consists of the paraffin and polyethylene.

[0022] In some embodiments, in the paraffin composite, the mass percentage of the polyethylene is 5% to 10%.

[0023] In some embodiments, the removing of the carrier from the thinned wafer includes:

[0024] Heat the carrier to melt it into a liquid paraffin composite, and remove the liquid paraffin composite.

[0025] In some embodiments, after removing the liquid paraffin composite, it further includes:

[0026] Clean the wafer in an acetone solution to remove the residual paraffin composite on the wafer;

[0027] The wafer after the cleaning process is rinsed to remove the residues on the surface of the wafer after the cleaning process;

[0028] The wafer after the rinsing process is dried.

[0029] In some embodiments, the cleaning process satisfies at least one of the following (i) - (ii), and / or the rinsing process satisfies at least one of the following (iii) - (iv):

[0030] (i) The cleaning process is ultrasonic cleaning;

[0031] (ii) The duration of the cleaning process is 40s - 100s;

[0032] (iii) The wafer after the cleaning process is rinsed with plasma water;

[0033] (iv) The duration of the rinsing process is 20s - 60s.

[0034] Compared with the prior art, the beneficial effects of the embodiments of the present application are as follows: The wafer processing method includes: providing a wafer, the front surface of the wafer has a circuit structure; forming a carrier on the front surface of the wafer, the material of the carrier is paraffin composite, and the density of the paraffin composite is greater than the density of paraffin; thinning the back surface of the wafer with the carrier formed thereon to reduce the thickness of the wafer; removing the carrier on the thinned wafer. Through the embodiments of the present application, using paraffin composite as the carrier can not only effectively protect the circuit structure on the front surface of the wafer and improve the product yield, but also after thinning the wafer, there is no need to perform debonding, and the process cost is relatively low. It is applicable to wafers of various thicknesses and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a flowchart of the wafer processing method according to the embodiment of the present application;

[0036] Figure 2 It is a schematic diagram of the wafer structure provided in step S11 of the wafer processing method according to the embodiment of the present application;

[0037] Figure 3 It is a schematic diagram of the intermediate structure obtained in step S12 of the wafer processing method according to the embodiment of the present application;

[0038] Figure 4 It is a schematic diagram of the intermediate structure obtained in step S13 of the wafer processing method according to the embodiment of the present application;

[0039] Figure 5 It is a schematic diagram of the thinned wafer structure obtained in step S14 of the wafer processing method according to the embodiment of the present application;

[0040] Figure 6Schematic structural diagram of the carrier preparation device in the wafer processing method of the embodiment of the present application;

[0041] Figure 7 is Figure 6 Schematic structural diagram of the plastic fixing cylinder in the shown carrier preparation device;

[0042] Figure 8 is Figure 6 Schematic structural diagram of the tray in the shown carrier preparation device;

[0043] Figure 9 is Figure 6 Schematic diagram of the usage state of the shown carrier preparation device;

[0044] Figure 10 is Figure 6 Schematic diagram of the usage state of the shown carrier preparation device;

[0045] Figure 11 is Figure 10 A - A cross-sectional view of;

[0046] Figure 12 Schematic structural diagram of the carrier preparation device in the wafer processing method of the embodiment of the present application;

[0047] Figure 13 is Figure 12 Schematic diagram of the usage state of the shown carrier preparation device;

[0048] Figure 14 is Figure 13 B - B cross-sectional view of;

[0049] Figure 15 Schematic diagram of the usage state of the carrier preparation device in the wafer processing method of the embodiment of the present application;

[0050] Figure 16 Schematic diagram of the usage state of the carrier preparation device in the wafer processing method of the embodiment of the present application;

[0051] Wherein: 1 - wafer (1a - front side, 1b - back side), 2 - carrier, 3 - tray (301 - tray body, 302 - flange part, 303 - limit groove, 304 - positioning groove), 4 - plastic fixing cylinder (401 - plastic fixing cavity), 5 - ejector post (501 - post body, 502 - base body). Detailed implementation manners

[0052] To facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant drawings. The preferred embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure content of the present application more thorough and comprehensive.

[0053] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there can also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time.

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0055] As used herein, the description "a1~a2" means "greater than or equal to a1" and "less than or equal to a2". For example, if x is 0~1, that is: 0≤x≤1.

[0056] Please refer to Figure 1 , the wafer processing method of the embodiment of this application includes the following steps S11 to step S14:

[0057] Step S11, provide a wafer 1, please refer to Figure 2 , the wafer 1 has a front surface 1a and a back surface 1b that are oppositely arranged in the thickness direction, and the front surface 1a of the wafer 1 has a circuit structure.

[0058] Exemplarily, the wafer 1 can be a 6-inch wafer, or the wafer 1 can be an 8-inch wafer, or the wafer 1 can be a 12-inch wafer, etc.

[0059] In this embodiment, the thickness of the wafer 1 can be any thickness and can be set according to the actual situation. That is to say, this processing method is applicable to processing wafers of various thicknesses and has a wide range of applications.

[0060] Step S12, form a carrier 2 on the front surface 1a of the wafer 1, as Figure 3 shown. The material of the carrier 2 is a paraffin composite, and the density of the paraffin composite is greater than the density of paraffin.

[0061] In this embodiment, the material of the carrier 2 is a paraffin composite with relatively high hardness. During the formation of the carrier 2, the carrier 2 can adhere to the front surface 1a of the wafer 1 through its own adhesiveness. That is to say, in this embodiment, the paraffin composite is both a carrier and an adhesive, without the need to use other adhesives, and without the need for bonding and debonding, the process is simpler, and the process cost is reduced.

[0062] In some embodiments, step S12 can specifically include: pouring a liquid paraffin composite on the front surface 1a of the wafer 1 and cooling the liquid paraffin composite to form a solid paraffin composite, and the solid paraffin composite is the carrier 2.

[0063] In some embodiments, the paraffin wax composite includes paraffin wax and polyethylene. Polyethylene can effectively increase the heat resistance, adhesion, and hardness of the paraffin wax composite, effectively ensure the compressive strength and stability of the carrier 2 at room temperature, and enable the solidified paraffin wax composite to adhere more firmly to the front surface 1a of the wafer 1.

[0064] As an embodiment, the paraffin wax composite is composed of paraffin wax and polyethylene. That is to say, the paraffin wax composite can only include paraffin wax and polyethylene, with simple composition and easy preparation.

[0065] Exemplarily, in the paraffin wax composite, the mass percentage of polyethylene is 5% - 10%. For example, the mass percentage of polyethylene can be, but is not limited to, 5%, 6%, 7%, 8%, 9%, or 10%. The melting point of the paraffin wax composite can be between 90°C and 105°C. The carrier 2 has relatively high hardness at room temperature, and the compressive strength is about 20 MPa.

[0066] In some examples, in the paraffin wax composite, the mass percentage of paraffin wax is 95% and the mass percentage of polyethylene is 5%. In some examples, in the paraffin wax composite, the mass percentage of paraffin wax is 90% and the mass percentage of polyethylene is 10%.

[0067] It should be noted that in other embodiments, the paraffin wax composite can also include other components, which can be set according to actual situations and will not be elaborated here.

[0068] As an embodiment, in step S12, a carrier preparation device is used to form the carrier 2 on the front surface 1a of the wafer 1. Please refer to Figures 6 to 14 , the carrier preparation device includes a tray 3 and a plastic solidifying cylinder 4. Among them, the tray 3 is used to place the wafer 1 and the plastic solidifying cylinder 4. The plastic solidifying cylinder 4 is a hollow cylindrical structure. The plastic solidifying cylinder 4 has a plastic solidifying cavity 401, and the plastic solidifying cavity 401 penetrates through the plastic solidifying cylinder 4, and the inner diameter of the plastic solidifying cavity 401 is equal to the outer diameter of the wafer 1, so as to prevent the liquid paraffin wax composite from leaking between the plastic solidifying cavity 401 and the wafer 1 when pouring the liquid paraffin wax composite.

[0069] Exemplarily, the wafer 1 can be a 6-inch wafer, and the inner diameter of the plastic solidifying cavity 401 can be 150 mm. Or, the wafer 1 can be an 8-inch wafer, and the inner diameter of the plastic solidifying cavity 401 can be 200 mm. Or, the wafer 1 can be a 12-inch wafer, and the inner diameter of the plastic solidifying cavity 401 can be 300 mm. It should be noted that in other embodiments, the wafer 1 and the plastic solidifying cylinder 4 can also be of other sizes, which can be set according to actual needs.

[0070] Exemplarily, step S12 specifically includes the following steps S121 to S124:

[0071] Step S121, place the wafer 1 on the tray 3, please refer to Figure 9 as shown. The back surface 1b of the wafer 1 placed on the tray 3 is in contact with the tray 3, and the front surface 1a of the wafer 1 faces upward. That is to say, the side of the wafer 1 with the circuit structure faces away from the tray 3.

[0072] Step S122, place the plastic cylinder 4 on the tray 3 from top to bottom, and make the wafer 1 placed on the tray 3 be received in the plastic cavity 401.

[0073] Wherein, the lower surface of the plastic cylinder 4 placed on the tray 3 is in contact with the tray 3. Since the outer diameter of the wafer 1 is equal to the inner diameter of the plastic cavity 401, during the subsequent injection of the liquid paraffin composite into the plastic cavity 401, the liquid paraffin composite will not overflow from between the wafer 1 and the plastic cylinder 4 onto the tray 3.

[0074] In this embodiment, the wafer 1 is placed first, and then the plastic cylinder 4 is sleeved outside the wafer 1. Compared with placing the plastic cylinder 4 first and then placing the wafer 1 into the plastic cylinder 4, it can better avoid wafer 1 fragmentation and the operation is simpler.

[0075] Step S123, inject the liquid paraffin composite into the plastic cavity 401 to make the liquid paraffin composite completely cover the front surface 1a of the wafer 1, and then cool and solidify the liquid paraffin composite in the plastic cavity 401 into a solid paraffin composite to form the carrier 2, please refer to Figure 10 and Figure 11 the embodiments shown, as well as Figure 13 and Figure 14 the embodiments shown.

[0076] In this embodiment, the carrier 2 completely covers the front surface 1a of the wafer 1, which can effectively shield the circuit structure on the front surface 1a of the wafer 1, thereby effectively protecting the circuit structure, and further avoiding accidental damage to the circuit structure when thinning the wafer. For example, it can avoid scratching, contamination or chemical corrosion of the circuit structure, etc. And, the liquid paraffin composite completely wets the surface of the wafer 1 when in the liquid state, fills the microscopic uneven structure on the surface of the wafer 1, and the solidified paraffin composite tightly wraps the wafer 1 through the mechanical stress generated by shrinkage, forming a physical interlock without the need to additionally use other adhesives or bonding processes. Using the solidified paraffin composite as the carrier 2 can not only maintain the strength of the carrier 2, but also easily remove the carrier 2 by heating in subsequent processes, simplifying the carrier 2 separation process.

[0077] In some examples, in step S123, the paraffin wax composite can be first heated and melted into a liquid state, and then the liquid paraffin wax composite is injected into the solid plastic cavity 401. For example, the paraffin wax composite can be heated to 100 °C. It should be noted that in other embodiments, the paraffin wax composite can also be heated to other temperatures, which can be set according to the melting point of the paraffin wax composite and other actual situations, and are not limited herein.

[0078] In some examples, in step S123, the liquid paraffin wax composite can be allowed to cool and solidify naturally, that is, the liquid paraffin wax composite is cooled at room temperature, and the process is simpler. In other embodiments, other equipment can also be used to accelerate the cooling and solidification of the paraffin wax composite, which can be set according to the actual situation and will not be elaborated herein.

[0079] In some embodiments, the thickness of the carrier 2 is 25 μm to 200 μm. For example, the thickness of the carrier 2 can be, but is not limited to, 25 μm, 30 μm, 35 μm, 40 μm, 50 μm, 70 μm, 100 μm, 110 μm, 140 μm, 150 μm, 170 μm, 185 μm or 200 μm, etc.

[0080] It can be understood that the thickness of the carrier 2 is related to the thickness of the thinned wafer 1. The thinner the thickness of the thinned wafer 1, the thicker the thickness of the carrier 2 can be. The thicker the thickness of the thinned wafer 1, the thinner the thickness of the carrier 2 can be. In some examples, when the thickness of the thinned wafer 1 is less than or equal to 100 μm, the thickness of the carrier 2 can be 200 μm. In some examples, when the thickness of the thinned wafer 1 is 200 μm, the thickness of the carrier 2 can be 80 μm to 100 μm.

[0081] Step S124, take out the wafer 1 formed with the carrier 2 from the carrier preparation device, as Figure 3 shown. For example, first pick up the solid plastic cylinder 4 containing the carrier 2 and the wafer 1 from the tray 3, and then take out the wafer 1 formed with the carrier 2 from the solid plastic cylinder 4.

[0082] In this embodiment, the carrier preparation device can be repeatedly recycled, further reducing the process cost.

[0083] In some embodiments, please refer to Figures 6 to 14 , the tray 3 may include a tray body 301 and a flange portion 302. The flange portion 302 is formed at the edge of the tray body 301, and the flange portion 302 is a closed annular structure protruding from the upper end of the tray body 301. The flange portion 302 and the tray body 301 jointly enclose a limit groove 303. The limit groove 303 can not only play a certain limiting role on the wafer 1 and the solid plastic cylinder 4, avoiding the wafer 1 and the solid plastic cylinder 4 from accidentally slipping off the tray 3, but also prevent the liquid paraffin wax composite accidentally dripping onto the tray body 301 from flowing out of the tray 3.

[0084] Exemplarily, the disk body 301 can be Figure 6 the square disk shown, or the disk body 301 can be a circular disk, or the disk body 301 can be of other shapes.

[0085] As an implementation manner, please refer to Figures 6 to 11 shown in the figure, the disk body 301 is a square disk, the upper surface of the disk body 301 is a plane, and the plastic fixing cylinder 4 is a cylindrical tubular structure. The side length of the disk body 301 can be set according to actual needs. Exemplarily, the side length of the disk body 301 can be greater than 300 mm, and the disk body 301 can be used in cooperation with plastic fixing cylinders 4 of various different sizes, so as to be applicable to wafers 1 of different sizes, thereby reducing the use cost. For example, the carrier preparation device can be applicable to processing 6-inch wafers, or 8-inch wafers, or 12-inch wafers.

[0086] As an implementation manner, please refer to Figures 12 to 14 , the disk body 301 is a square disk, and a positioning groove 304 recessed downward with respect to the upper surface of the disk body 301 is formed in the upper surface of the disk body 301. The positioning groove 304 can be used to position the wafer 1, that is, the wafer 1 placed on the tray 3 can be received in the positioning groove 304. The shape of the positioning groove 304 is the same as the shape of the wafer 1, and the diameter of the positioning groove 304 is the same as the diameter of the wafer 1. Therefore, the wafer 1 can be exactly placed in the positioning groove 304, and the wafer 1 placed in the positioning groove 304 will not move relative to the tray 3. The plastic fixing cylinder 4 is a tubular structure with a square outer and a circular inner. The plastic fixing cylinder 4 can just be inserted into the limiting groove 303, and the plastic fixing cylinder 4 inserted into the limiting groove 303 and placed on the disk body 301 is coaxially arranged with the wafer 1 and can just receive the wafer 1.

[0087] Exemplarily, the height of the positioning groove 304 can be less than the thickness of the wafer 1. Please refer to Figure 14 shown in the figure. Therefore, the upper surface of the wafer 1 placed in the positioning groove 304 is higher than the upper surface of the disk body 301, so that a part of the wafer 1 can be received in the positioning groove 304 and another part can be received in the plastic fixing cavity 401.

[0088] In this implementation manner, the tray 3 can effectively position the wafer 1 and the plastic fixing cylinder 4 respectively, so as to ensure the effective docking of the wafer 1 and the plastic fixing cylinder 4 and avoid accidental crushing of the wafer 1 by the plastic fixing cylinder 4.

[0089] As an implementation manner, the plastic fixing cylinder 4 can be made of an alloy, which can prevent the paraffin composite from adhering to the inner wall of the plastic fixing cylinder 4, making it more convenient to take out the wafer 1 with the carrier 2 formed thereon from the plastic fixing cylinder 4. For example, the plastic fixing cylinder 4 can be a steel mold made by alloy casting. It should be noted that in other implementation manners, the plastic fixing cylinder 4 can also be made of other materials, which can be set according to actual needs and will not be elaborated here.

[0090] In some implementation manners, in order to facilitate taking out the wafer 1 with the carrier 2 formed thereon from the carrier preparation device, please refer to Figure 15 and Figure 16 , the carrier preparation device can further include an ejector post 5, and the ejector post 5 has a column body 501 that matches the plastic fixing cavity 401. The plastic fixing cylinder 4 can be placed on the ejector post 5 from top to bottom. When the plastic fixing cylinder 4 is placed on the ejector post 5, the end of the plastic fixing cylinder 4 that houses the wafer 1 faces upward and the end away from the wafer 1 faces downward. Then move the plastic fixing cylinder 4 downward. During the downward movement of the plastic fixing cylinder 4, the distance between the carrier 2 and the ejector post 5 becomes smaller and smaller, and then the carrier 2 contacts the ejector post 5. Please refer to Figure 15 . During the continuous downward movement of the plastic fixing cylinder 4, the wafer 1 and the carrier 2 are gradually ejected out of the plastic fixing cylinder 4 by the ejector post 5, so as to take out the wafer 1 with the carrier 2 formed thereon from the plastic fixing cylinder 4. Please refer to Figure 16 shown. Finally, the wafer 1 with the carrier 2 formed thereon can be removed from the ejector post 5, which is convenient to use.

[0091] As an implementation manner, please refer to Figure 15 and Figure 16 shown. The ejector post 5 can further include a base body 502. The base body 502 is formed at the lower end of the column body 501, and the diameter of the base body 502 is larger than that of the column body 501. This can not only make the column body 501 more stable and further prevent the column body 501 from tipping over, but also, during the process of removing the plastic fixing cylinder 4 from the column body 501, the base body 502 can be used as a handle, making it more convenient to apply force and more convenient to use.

[0092] It should be noted that other methods can also be used to take out the wafer 1 with the carrier 2 formed thereon from the plastic fixing cylinder 4, which can be set according to the actual situation.

[0093] Step S13, thinning the back surface 1b of the wafer 1 with the carrier 2 formed thereon to reduce the thickness of the wafer 1. Please refer to Figure 4 shown.

[0094] Exemplarily, in step S13, a mechanical grinding method can be used for thinning. When performing mechanical grinding, the carrier 2 and the wafer 1 can be adsorbed and fixed on the operating table by means of vacuum adsorption. Here, the adsorption surface is the surface of the carrier 2 away from the wafer 1. It should be noted that in other embodiments, other methods such as chemical methods can also be used for thinning, which can be set according to actual situations.

[0095] It should be noted that the thinning process in this application is prior art and will not be elaborated here.

[0096] Step S14, remove the carrier 2 on the thinned wafer 1 to obtain the thinned wafer 1. Please refer to Figure 5 as shown.

[0097] In some embodiments, step S14 includes step S141:

[0098] Step S141, heat the carrier 2 to melt it into a liquid paraffin complex and remove the liquid paraffin complex.

[0099] Exemplarily, the carrier 2 and the thinned wafer 1 can be placed in a container. At this time, the carrier 2 is at the lower end of the thinned wafer 1. Then heat the carrier 2 to completely melt it into a liquid, and then take out the thinned wafer 1 from the container. The operation is simple. In some examples, the thinned wafer 1 can be picked up from the container with tweezers.

[0100] In some embodiments, after step S141, step S14 further includes steps S142 to S144:

[0101] Step S142, immerse the thinned wafer 1 in an acetone solution and perform a cleaning process on the thinned wafer 1 in the acetone solution to completely remove the residual paraffin complex on the thinned wafer 1.

[0102] As one embodiment, the cleaning process is ultrasonic cleaning. Step S142 is specifically to immerse the thinned wafer 1 in an acetone solution and clean it with an ultrasonic cleaner.

[0103] As one embodiment, the duration of the cleaning process is 40s to 100s. Exemplarily, the duration of the cleaning process can be, but is not limited to, 40s, 45s, 50s, 60s, 75s, 80s, 95s or 100s, etc.

[0104] Step S143, perform a rinsing process on the wafer 1 after the cleaning process to remove the residues on the surface of the wafer 1 after the cleaning process.

[0105] As an implementation manner, in step S143, the washed wafer 1 is rinsed with plasma water.

[0106] As an implementation manner, the duration of the rinsing process is 20s to 60s. Exemplarily, the duration of the rinsing process can be, but is not limited to, 20s, 25s, 30s, 35s, 40s, 45s, 50s, or 60s, etc.

[0107] Step S144, the rinsed wafer 1 is dried.

[0108] As an implementation manner, in step S143, the drying process can be spin-drying. Exemplarily, the duration of the drying process is 20s to 60s. Exemplarily, the duration of the drying process can be, but is not limited to, 20s, 25s, 30s, 35s, 40s, 45s, 50s, or 60s, etc.

[0109] It should be noted that in other implementation manners, the drying process can be air-drying or baking or other drying methods, which can be set according to the actual situation.

[0110] In the related art, the front protection during wafer thinning includes coating protection, film protection, and temporary bonding. Among them, coating protection is to spin-coat photoresist or polymer, such as polyimide and anti-reflection coating, on the front of the wafer to form a uniform protective layer. However, uneven coating may cause local protection failure, and organic substances may remain during removal, making it difficult to ensure complete removal of residual organic substances. Film protection is to cover the front of the wafer with a film to prevent scratching, contamination, or chemical corrosion of the circuit pattern. However, the film process is not applicable to thinner wafers, such as wafers with a thickness of less than 100μm after thinning. The self-stress and warpage of the thinned wafer are relatively large, and there is a high risk of fragmentation. In addition, the thickness and adhesion of the film need to be precisely controlled, and excessive adhesion may cause damage to the wafer surface during peeling. Temporary bonding is to temporarily bond the wafer to a rigid carrier such as glass or silicon wafer to ensure that the wafer remains flat and stable during the thinning process. Although the temporary bonding process is applicable to the thinning of thinner wafers, after the wafer is thinned, the bonding needs to be released and the wafer needs to be cleaned. The process cost is relatively high, and there may be a risk of residues or damage to the front of the wafer during the release of the bonding.

[0111] However, the wafer processing method of this embodiment not only has a relatively low process cost and low process complexity, but also has a good protection effect on the wafer 1, will not damage the circuit structure on the front of the wafer 1, and has no residues, which can effectively ensure the product yield of the wafer 1. Moreover, this wafer processing method can be applied to wafers of any thickness, and can even be applied to ultra-thin wafers, that is, wafers with a thickness of less than 50μm.

[0112] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0113] The above embodiments only express the preferred embodiments of the present application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A wafer processing method, characterized in that, Including: Providing a wafer, the front side of the wafer having a circuit structure; Forming a carrier on the front side of the wafer, the material of the carrier being a paraffin composite, the density of the paraffin composite being greater than the density of paraffin; Performing a thinning process on the back side of the wafer formed with the carrier to thin the thickness of the wafer; Removing the carrier on the thinned wafer.

2. The wafer processing method according to claim 1, wherein Using a carrier preparation device to form a carrier on the front side of the wafer; The carrier preparation device includes a tray and a plastic fixing cylinder, the plastic fixing cylinder having a plastic fixing cavity penetrating through the plastic fixing cylinder, the inner diameter of the plastic fixing cavity being equal to the outer diameter of the wafer; The using the carrier preparation device to form a carrier on the front side of the wafer includes: Placing the wafer face up on the tray; Placing the plastic fixing cylinder on the tray so that the wafer placed on the tray is received in the plastic fixing cavity; Injecting a liquid paraffin composite into the plastic fixing cavity to completely cover the front side of the wafer with the liquid paraffin composite, and cooling the liquid paraffin composite to form the carrier; Taking out the wafer formed with the carrier from the carrier preparation device.

3. The wafer processing method according to claim 2, wherein, The plastic fixing cylinder is made of an alloy.

4. The wafer processing method according to claim 1, wherein The thickness of the carrier is 25 μm to 200 μm.

5. The wafer processing method according to claim 1, wherein The paraffin composite includes paraffin and polyethylene.

6. The wafer processing method according to claim 5, wherein The paraffin composite is composed of the paraffin and polyethylene.

7. The wafer processing method according to claim 6, characterized in that, In the paraffin composite, the mass percentage of the polyethylene is 5% to 10%.

8. The wafer processing method according to claim 2, wherein The removing the carrier on the thinned wafer includes: Heating the carrier to melt it into a liquid paraffin composite and removing the liquid paraffin composite.

9. The wafer processing method according to claim 8, wherein, After removing the liquid paraffin composite, it further includes: Performing a cleaning process on the wafer in an acetone solution to remove the residual paraffin composite on the wafer; Performing a rinsing process on the wafer after the cleaning process to remove the residues on the surface of the wafer after the cleaning process; Performing a drying process on the wafer after the rinsing process.

10. The wafer processing method according to claim 9, characterized in that, The cleaning process satisfies at least one of the following (i) to (ii), and / or, the rinsing process satisfies at least one of the following (iii) to (iv): (i) The cleaning process is an ultrasonic cleaning; (ii) The duration of the cleaning process is 40 s to 100 s; (iii) Rinsing the wafer after the cleaning process with plasma water; (iv) The duration of the rinsing process is 20 s to 60 s.

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