Cryogenic peeling method for wafter

Abstract

The present invention relates to a cryogenic peeling method for a wafter, which comprises the following steps: coating a liquid water-soluble medium on an end face of an ingot and / or clamping surfaces of temperature control clamps, cooling the water-soluble medium under the action of the temperature control clamps for curing to fix the ingot between the pair of temperature control clamps; and moving at least one temperature control clamp until a modified layer of the ingot is separated, and after peeling is completed, heating the water-soluble medium in the solid state under the action of the temperature control clamps for liquefaction to obtain a wafer and the remaining ingot. The present invention has advantages of involving high peeling efficiency, saving cleaning process, involving easy control of peeling conditions, low cracking risk, and simple operation, and being suitable for large-scale industrial application.

Description

Wafer cryo-peeling method Technical Field

[0001] The present invention relates to the technical field of wafer processing, and in particular to a wafer freezing and peeling method. Background Art

[0002] Currently, the most advanced chip manufacturing process requires nearly 4,000 steps. These include wafer processing (raw materials, ingots, and wafers), wafer manufacturing (front-end processes, including deposition, lithography, etching, ion implantation, and metallization), and packaging and testing (back-end processes), encompassing cutting, die placement, and bonding. Lasers, thanks to their applicability in cutting, drilling, and welding, primarily offer new process solutions for wafer processing and packaging and testing.

[0003] In terms of wafer processing, laser can cut the grown ingot into wafers. As an alternative to the current mortar wire or diamond wire cutting, laser slicing has higher precision and efficiency, less impact on the material and less loss, and is therefore more suitable for cutting high-hardness and high-brittle materials such as SiC wafers (third-generation semiconductors). Currently, after using laser to process and modify the surface of the ingot below the surface, the wafer is peeled off from the ingot with the help of external force. Compared with the traditional wire cutting method, the laser slicing method has the advantages of high efficiency and low loss, but a reliable peeling method is needed to ensure the success rate and efficiency of wafer peeling. It is also necessary to ensure that the cleaning process after peeling is simple for the wafer to remove contamination from the previous process and create conditions for the next process.

[0004] The Chinese patent application number CN115410979B filed by the applicant recently discloses a method for peeling wafers, wherein a hot-melt adhesive is used to bond the sample to be peeled to the wafer after laser processing and then the wafer is peeled off. In addition, the Chinese patent application number CN113972160A discloses a method for laser slicing of solid materials, wherein a laser is used to form a peeling surface inside the solid material; a thermoplastic glue is preheated to the glass transition temperature, and then applied to the surface of the solid material in a heated state, and then naturally cooled to produce stress cracks due to differences in thermal expansion coefficients, thereby obtaining a thin layer wafer. The thermoplastic glue or hot-melt adhesive used in the above method will have residual adhesive on the surface of the wafer that is peeled off, and requires another process for cleaning, and cannot directly enter the thinning and polishing process.

[0005] Chinese patent publication number CN115138987A discloses a method for peeling silicon carbide wafers. This involves heating and cooling the thick and thin layers of silicon carbide that have been modified by laser processing, creating a temperature difference between the thin and thick layers, breaking the physical connection between them, and ultimately peeling them off. Meanwhile, patent publication number CN115513043A discloses a method for peeling a wafer from a silicon carbide ingot. This involves injecting a pre-prepared liquid into the modified layer of the silicon carbide ingot using ultrasonic vibration. Once the liquid fills the modified layer, the silicon carbide ingot is cooled until the liquid freezes, causing the modified layer to expand and fracture, allowing the wafer layer to be peeled off from the silicon carbide substrate. In the above method, due to the high thermal conductivity of silicon carbide material, it is difficult to form a relatively large temperature difference on both sides of silicon carbide to achieve peeling; in addition, the solution of injecting liquid cooling into the modified layer, because the liquid can only penetrate into the cracks caused by laser processing, but cannot penetrate into the laser processing trace area, there will be uneven force during cooling and expansion. Silicon carbide wafers are hard and brittle materials and have a high risk of breakage. Moreover, this solution is difficult to implement in an automated production line.

[0006] Chinese patent publication number CN111106032A discloses a wafer production device, which positions the focal point of a laser beam of a wavelength that is transparent to the crystal ingot at a depth from the upper surface of the crystal ingot equivalent to the thickness of the wafer to be produced, and irradiates the crystal ingot with laser beams to form a peeling layer; the wafer is then peeled from the crystal ingot by a wafer peeling unit. The above method uses an adsorption sheet to adsorb the upper surface of the crystal ingot, and places the entire crystal ingot in a liquid environment, applies ultrasonic action to reduce the strength of the peeling layer, and then controls the adsorption sheet to rise by a cylinder to peel the wafer. When the above device applies ultrasonic action, if the cracks inside the peeling layer are not uniform and flat, the ultrasonic time needs to be extended. There is no standard for evaluating whether the peeling strength has fallen below the suction cup adsorption force. In addition, if the ultrasonic action fails to reduce the peeling layer strength to below the suction cup adsorption force, it is difficult to peel. Moreover, applying ultrasonic action in a liquid environment increases the complexity of the device and there is a risk of liquid leakage.

[0007] In summary, the existing wafer peeling process usually adopts one or a combination of mechanical stretching peeling, bonding or adsorption fixing of wafers to assist peeling, using temperature difference or liquid cooling expansion to destroy the physical connection of the modified layer, and ultrasonic assistance to reduce the strength of the peeling layer to complete the peeling of thin wafers on the ingot. However, these methods have problems such as low peeling efficiency, complex post-cleaning process, difficult to control peeling conditions, high risk of cracking, and complex equipment. They are not suitable for large-scale industrial applications and need to be improved.

[0008] Summary of the Invention

[0009] The problem to be solved by the present invention is to provide a wafer freezing peeling method in response to the above-mentioned shortcomings in the prior art, which has the advantages of high peeling efficiency, saving cleaning process, easy control of peeling conditions, low risk of cracking, simple operation, and suitability for large-scale industrial applications.

[0010] The above-mentioned object of the present invention is achieved through the following technical solutions:

[0011] A wafer cryo-peeling method comprises the following steps:

[0012] S1: After coating a liquid water-soluble medium on the end surface of the ingot and / or the clamping surface of the temperature-controlled clamp, the water-soluble medium is cooled and solidified under the action of the temperature-controlled clamp, thereby completing the fixation of the ingot between the pair of temperature-controlled clamps;

[0013] S2 moves at least one temperature-controlled clamp until the modified layer of the ingot is separated. After the stripping is completed, the solid water-soluble medium is heated and liquefied under the action of the temperature-controlled clamp to obtain a wafer and a remaining ingot.

[0014] Furthermore, in S1, the water-soluble medium is a combination of one or more of water, water-soluble organic matter, and water-soluble inorganic matter. Specifically, the combination of at least two water-soluble organic matter, at least two water-soluble inorganic matter, water and several water-soluble organic matter, water and several water-soluble inorganic matter, several water-soluble organic matter and several water-soluble inorganic matter, or water, several water-soluble organic matter, and several water-soluble inorganic matter.

[0015] Furthermore, in the above S1, the freezing point of the water-soluble medium is -50 to 80°C, and the dynamic viscosity at room temperature and pressure is 1.01×10 -3 ~100Pa·s.

[0016] Preferably, in S1, the freezing point of the water-soluble medium is -50, -40, -30, -20, -10, 0, 10, 20, 30, 40, 50, 60, 70 or 80°C, and the dynamic viscosity at room temperature and pressure is 1.01×10 -3 , 0.01, 0.1, 1.0, 10, 20, 50, 80 or 100 Pa·s.

[0017] Furthermore, in S1, in the composition of water, water-soluble organic matter, and / or water-soluble inorganic matter, the volume concentration of each water-soluble organic matter and each water-soluble inorganic matter in the composition is independently 0.5 to 35%. The composition of water, water-soluble organic matter, and / or water-soluble inorganic matter is specifically a composition of water and several water-soluble organic matter, a composition of water and several water-soluble inorganic matter, or a composition of water, several water-soluble organic matter, and several water-soluble inorganic matter.

[0018] Preferably, in said S1, in the composition of water, water-soluble organic matter and / or water-soluble inorganic matter, the volume concentration of each water-soluble organic matter and each water-soluble inorganic matter in the composition is independently 0.5, 0.8, 1.0, 5, 10, 15, 20, 25, 30 or 35%.

[0019] Furthermore, in S1, the water-soluble medium is a combination of one or more of water, a silane coupling agent, anionic polyacrylamide, cationic polyacrylamide, carboxymethyl cellulose and a surfactant.

[0020] Furthermore, in said S1, the coating method of the water-soluble medium is a coating method of one or more of drip coating, spin coating, scraping coating, spraying, brushing, rolling coating, dipping coating, and transfer coating using an adsorbent material adsorbed with the water-soluble medium. Among them, the water-soluble medium can be applied to the end face of the ingot and / or the clamping surface of the temperature-controlled fixture by pumping and draining with a syringe pump / peristaltic pump, etc., directly coated on the end face of the ingot and / or the clamping surface of the temperature-controlled fixture by spin coating / scraping coating / spraying / brushing / rolling coating / dipping coating, etc., and / or transferred coated on the end face of the ingot and / or the clamping surface of the temperature-controlled fixture by means of an adsorbent material, and the water-soluble medium is forced to diffuse by applying pressure with the temperature-controlled fixture and evenly distributed between the end face of the ingot and the clamping surface of the temperature-controlled fixture, or between the clamping surfaces of the pair of temperature-controlled fixtures, thereby completing the coating of the water-soluble medium on the end face of the ingot and / or the clamping surface of the temperature-controlled fixture.

[0021] Furthermore, in S1, the pressure applied by the temperature control fixture to the water-soluble medium during cooling and solidification is controlled to be 1 to 3000 N, the cooling temperature is 1 to 40° C. lower than the freezing point of the water-soluble medium, the cooling time is 10 to 600 s, and the amount of the water-soluble medium is controlled to be 0.1 to 20 mL, and the thickness after cooling and solidification is 20 to 200 μm.

[0022] Preferably, in said S1, the pressure applied by the temperature control fixture to the water-soluble medium during cooling and solidification is 1, 10, 50, 100, 150, 200, 250, 300, 350, 400, 550, 600, 650, 700, 750, 800, 850, 900, 1000, 1100, 1200, 1300, 1400, 1500, 16 00, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900 or 3000N, cooling temperature is 1, 2, 5, 8, 10, 15, 20, 25, 30, 35 or 40℃ below the freezing point of the water-soluble medium, cooling time is 10, 20, 30, 4 0, 50, 60, 70, 80, 90, 120, 150, 180, 210, 240, 270, 300, 330, 360, 390, 420, 450, 480, 510, 540, 570 or 600s, and control the amount of water-soluble medium to 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 mL, and the thickness after cooling and solidification is 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190 or 200 μm. Among them, the amount of water-soluble medium used when stripping a 4-inch ingot is preferably 3.5 mL, and the amount of water-soluble medium used when stripping a 6-inch ingot is preferably 8 mL.

[0023] Furthermore, in S2, the movement and stretching speed of the temperature-controlled clamp is controlled to be 0.01 to 5.00 mm / min.

[0024] Furthermore, the temperature control clamp includes a thermally conductive clamp, a cooling and heating module arranged on the thermally conductive clamp, and a plurality of temperature detection modules. The cooling and heating module cools or heats in a manner that diffuses from the central area of ​​the thermally conductive clamp to the peripheral area. These temperature detection modules are installed on the thermally conductive clamp with the detection end facing the clamping surface, and are arranged sequentially along the diffusion path of the cooling and heating module.

[0025] Furthermore, the temperature control fixture further comprises a plurality of liquid injection channels opened on the thermally conductive clamping base, wherein the liquid inlet of the liquid injection channel is used to receive the water-soluble medium, and the liquid outlet is arranged on the clamping surface of the thermally conductive clamping base.

[0026] Furthermore, the diffusion path of the cooling and heating module is one or a combination of a row diffusion path, a grid-interwoven diffusion path, a concentric circle diffusion path and a vortex line diffusion path.

[0027] Furthermore, the cooling and heating module includes a plurality of semiconductor cooling chips arranged along a diffusion path. A semiconductor cooling chip, also known as a thermoelectric cooling chip, is a type of heat pump. Its advantage is that it has no sliding parts and can be used in applications with limited space, high reliability requirements, and no refrigerant pollution. It utilizes the Peltier effect of semiconductor materials. When direct current passes through a galvanic couple composed of two different semiconductor materials connected in series, heat is absorbed and released at both ends of the galvanic couple, achieving both cooling and heating. The semiconductor cooling chips can be square in size ranging from 10mm*10mm to 60mm*60mm, and are evenly distributed horizontally on the thermal clamp. To further enhance the cooling effect of the semiconductor cooling chips, at least two semiconductor cooling chips can be stacked.

[0028] Preferably, a water-cooling block is provided on the side of the semiconductor cooling plate facing away from the clamping surface of the thermally conductive clamp, using conductive silver paste. A water-cooling block is a metal block made of copper or aluminum with internal water channels. To ensure effective heat dissipation, each water-cooling block is connected to a water chiller via a liquid injection port. This parallel connection, compared to a series connection of water-cooling blocks, results in a more consistent water-cooling temperature across the semiconductor cooling plate, thereby ensuring effective cooling.

[0029] Preferably, a heat dissipation channel is provided on the side of the semiconductor cooling fins facing away from the clamping surface of the thermally conductive clamp, through thermally conductive silicone grease. The cooling medium in the heat dissipation channel flows sequentially through the semiconductor cooling fins from the inside out. The orthographic projection of the heat dissipation channel on the clamping surface of the thermally conductive clamp forms a spiral line, ensuring uniform heat dissipation from the semiconductor cooling fins. The cooling medium in the heat dissipation channel is a coolant or cold air with a freezing point below -50°C.

[0030] Alternatively, the cooling and heating module includes a liquid inlet arranged near the center of the thermal clamp, a liquid outlet arranged near the periphery of the thermal clamp, and a hot and cold medium channel arranged between the liquid inlet and the liquid outlet, and the positive projection of the hot and cold medium channel on the clamping surface of the thermal clamp is a spiral line.

[0031] Preferably, the heating medium of the hot and cold medium channels is a heating liquid or hot air with a boiling point above 100°C, the exhaust medium of the hot and cold medium channels is compressed air, and the cooling medium of the hot and cold medium channels is a cooling liquid or cold air with a freezing point below -50°C.

[0032] Furthermore, the temperature detection modules are temperature sensors that detect the temperature of various regions of the thermally conductive clamp, from the center region to the periphery, to control the temperature difference of the clamping surface of the temperature control fixture to within ±2°C. The temperature sensor may be, for example, a contact temperature sensor, preferably a PT100 temperature sensor, which is in contact with the interior of the temperature control fixture via thermal grease.

[0033] In summary, the beneficial technical effects of the present invention are:

[0034] 1. In the peeling method of the present invention, the water-soluble medium is cooled to below the freezing point by a temperature-controlled fixture to achieve a freezing effect of cooling and solidification, and the wafer can be directly stretched and peeled. After peeling, the water-soluble medium is reheated to above the freezing point, and the wafer can be quickly removed. The surface of the peeled wafer only needs to be simply purged to remove the water-soluble medium before entering the next thinning process. The thinning process itself involves flushing, and the water-soluble medium dissolves and disappears during the flushing process. Compared with the gluing or wax gluing method, the cleaning process is omitted, and the operation is more convenient.

[0035] 2. During the peeling process of the present invention, since wafers generally have good thermal conductivity, freezing can be achieved by simply cooling one side of the wafer to be peeled. In addition, the water-soluble medium has good fluidity. By pressing the temperature-controlled fixture downward on the wafer surface, the water-soluble medium is evenly distributed. The surface to be peeled and the surface of the temperature-controlled fixture are completely in contact, and the problem of uneven force causing breakage will not occur.

[0036] 3. During the peeling process of the peeling method of the present invention, after the water-soluble medium is frozen, the bonding strength between the temperature-controlled fixture and the wafer to be peeled is much greater than the theoretical suction force (0.1 MPa) of the vacuum suction cup, etc., and the wafer separation with a large peeling force can be completed without the need for complex auxiliary peeling equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG1 is a schematic diagram of the connection relationship between the temperature control fixture and the crystal ingot according to Example 1 of the present invention.

[0038] FIG2 is a schematic structural diagram of a temperature control fixture according to Example 2 of the present invention.

[0039] FIG3 is a schematic structural diagram of a temperature control fixture according to Example 5 of the present invention.

[0040] FIG4 is a schematic structural diagram of a temperature control fixture according to Example 6 of the present invention.

[0041] In the figure, 1. ingot; 11. wafer; 12. modified layer; 13. remaining ingot; 2. temperature control fixture; 21. thermal clamp; 22. cooling and heating module; 221. semiconductor cooling plate; 222. liquid inlet; 223. liquid outlet; 224. hot and cold medium channels; 23. liquid injection channel; 24. temperature detection module; 25. water cooling block; 26. heat dissipation channel; 3. water-soluble medium. DETAILED DESCRIPTION

[0042] In order to make the technical means, creative features, objectives and functions achieved by the present invention clearer and easier to understand, the present invention is further explained below with reference to the accompanying drawings and specific implementation methods.

[0043] Example

[0044] Example 1: Referring to FIG1 , a method for freezing and peeling a wafer 11 disclosed in the present invention comprises the following steps:

[0045] S1: After coating the end face of the crystal ingot 1 and / or the clamping surface of the temperature control clamp 2 with a liquid water-soluble medium 3, the water-soluble medium 3 is cooled and solidified under the action of the temperature control clamp 2, thereby completing the fixation of the crystal ingot 1 between the pair of temperature control clamps 2;

[0046] S2 moves at least one temperature-controlled clamp 2 until the modified layer 12 of the ingot 1 is separated. After the stripping is completed, the solid water-soluble medium 3 is heated and liquefied under the action of the temperature-controlled clamp 2 to obtain a wafer 11 and a remaining ingot 13.

[0047] First, in S1, the water-soluble medium 3 is a combination of one or more of water, water-soluble organic matter and water-soluble inorganic matter, and the freezing point of the water-soluble medium 3 is -50 to 80°C, and the dynamic viscosity at room temperature and pressure is 1.01×10 -3 To further improve the low-temperature freezing ability of the water-soluble medium 3, in the composition of water, water-soluble organic matter and / or water-soluble inorganic matter, the volume concentration of each water-soluble organic matter and each water-soluble inorganic matter in the composition is independently 0.5 to 35%, and the water-soluble medium 3 can preferably be a combination of one or more of water, a silane coupling agent, anionic polyacrylamide, cationic polyacrylamide, carboxymethyl cellulose and a surfactant.

[0048] At the same time, the coating method of the water-soluble medium 3 is one or more of drip coating, spin coating, scraping coating, spraying, brushing, rolling, dipping, and transfer coating using an absorbent material adsorbed with the water-soluble medium 3. Among them, the water-soluble medium 3 can be pumped and drained by a syringe pump / peristaltic pump and dripped onto the end face of the ingot 1 and / or the clamping surface of the temperature-controlled clamp 2, directly coated on the end face of the ingot 1 and / or the clamping surface of the temperature-controlled clamp 2 by spin coating / scraping / spraying / brushing / rolling / dipping, and / or transferred onto the end face of the ingot 1 and / or the clamping surface of the temperature-controlled clamp 2 by means of an absorbent material. The water-soluble medium 3 is also spread by applying pressure by the temperature-controlled clamp 2 and evenly distributed between the end face of the ingot 1 and the clamping surface of the temperature-controlled clamp 2, or between the clamping surfaces of the pair of temperature-controlled clamps 2, to complete the coating of the water-soluble medium 3 on the end face of the ingot 1 and / or the clamping surface of the temperature-controlled clamp 2.

[0049] Secondly, in order to facilitate the uniform diffusion of the water-soluble medium 3 by applying pressure through the temperature control fixture 2 and to make the freezing performance of the water-soluble medium 3 suitable when cooled and solidified, before and after the cooling and solidification process, the pressure applied by the temperature control fixture 2 to the water-soluble medium 3 during cooling and solidification should be controlled to be 1~3000N, the cooling temperature should be 1~40℃ lower than the freezing point of the water-soluble medium 3, the cooling time should be 10~600s, and the amount of the water-soluble medium 3 should be controlled to be 0.1~20mL, and the thickness after cooling and solidification should be 20~200μm.

[0050] Finally, in S2 , by controlling the moving and stretching speed of the temperature-controlled clamp 2 to be 0.01-5.00 mm / min, the modified layer 12 of the crystal ingot 1 can be easily separated.

[0051] Example 2: Referring to Figures 1 and 2, a method for freezing and peeling a wafer 11 disclosed in the present invention is different from Example 1 in that the temperature control clamp 2 includes a heat-conducting clamp 21, a cooling and heating module 22 arranged on the heat-conducting clamp 21, a plurality of liquid injection channels 23 opened on the heat-conducting clamp 21, and a plurality of temperature detection modules 24.

[0052] Among them, the cooling and heating module 22 cools or heats in a manner of diffusing from the central area of ​​the heat conductive clamp 21 to the peripheral area, and the diffusion path of the cooling and heating module 22 is one or a combination of several of the following paths: a row-by-row diffusion path, a grid-interwoven diffusion path, a concentric circle diffusion path, and a vortex line diffusion path.

[0053] These injection channels 23 can be provided on one of the temperature control clamps 2, or can be provided on two temperature control clamps 2 respectively. In this embodiment, they are preferably provided on the upper temperature control clamp 2. The liquid inlet 222 of the injection channel 23 is used to receive the water-soluble medium 3, and the liquid outlet 223 is provided on the clamping surface of the thermal clamp 21. Specifically, the water-soluble medium 3 can be applied by dripping, that is, when applying, the clamping surfaces of the pair of temperature control clamps 2 are preliminarily placed in a state of upper and lower adhesion and gap arrangement, and then pumped and drained to the liquid inlet 222 of the injection channel 23 by a syringe pump / peristaltic pump, etc., and dripped onto the clamping surface of the other thermal clamp 21 through the liquid outlet 223 of the injection channel 23, and then pressure is applied to force the water-soluble medium 3 to diffuse and evenly distribute it between the clamping surfaces of the pair of temperature control clamps 2.

[0054] These temperature detection modules 24 are mounted on the thermal clamp 21 with their detection ends facing the clamping surface, and are arranged sequentially along the diffusion path of the cooling and heating modules 22. The temperature detection modules 24 are temperature sensors used to detect the temperature of various regions of the thermal clamp 21, from the center to the periphery, to control the temperature difference of the clamping surface of the temperature control fixture 2 to within ±2°C. The temperature sensor can be, for example, a contact temperature sensor, preferably a PT100 temperature sensor, which is in contact with the interior of the temperature control fixture 2 via thermal grease.

[0055] Example 3: Referring to Figure 2, a method for freezing and peeling off a wafer 11 disclosed in the present invention is different from Example 2 in that the diffusion path of the cooling and heating module 22 is a concentric diffusion path, and the cooling and heating module 22 includes a plurality of 10mm*10mm square semiconductor cooling plates 221 arranged along the diffusion path, and these semiconductor cooling plates 221 are evenly distributed horizontally on the thermal clamp 21.

[0056] To improve the cooling effect, a water-cooling block 25 is installed on the side of the conductive cooling plate facing away from the clamping surface of the thermally conductive clamp 21 through conductive silver paste. The water-cooling block 25 is a metal block made of copper or aluminum with internal water channels. To ensure effective heat dissipation, each water-cooling block 25 is connected to a water chiller through its injection hole for cooling. This parallel connection, compared to the series connection of the water-cooling blocks 25, ensures that the water-cooling temperature of the semiconductor cooling plate 221 is consistent, thereby ensuring effective cooling.

[0057] Example 4: This is a method for freezing and peeling a wafer 11 disclosed in the present invention. The difference from Example 3 is that in order to further improve the cooling effect of the semiconductor refrigeration plate 221, two semiconductor refrigeration plates 221 are arranged in a stacked manner.

[0058] Example 5: Referring to FIG3 , a method for cryo-peeling a wafer 11 disclosed in the present invention is shown. This method differs from Example 3 in that, to improve the cooling effect, a heat dissipation channel 26 is provided on the side of the semiconductor cooling fins 221 facing away from the clamping surface of the thermal clamp 21 through thermal grease. The cooling medium in the heat dissipation channel 26 flows through the semiconductor cooling fins 221 from the inside out. The orthographic projection of the heat dissipation channel 26 on the clamping surface of the thermal clamp 21 is a spiral line, ensuring uniform heat dissipation from the semiconductor cooling fins 221. The cooling medium in the heat dissipation channel 26 is cold air.

[0059] Example 6: Referring to Figure 4, a method for freezing and peeling off a wafer 11 disclosed in the present invention is different from Example 2 in that the diffusion path of the cooling and heating module 22 is a vortex line diffusion path, and the cooling and heating module 22 includes a liquid inlet 222 arranged near the center of the thermal clamp 21, a liquid outlet 223 arranged near the periphery of the thermal clamp 21, and a hot and cold medium channel 224 arranged between the liquid inlet 222 and the liquid outlet 223.

[0060] Correspondingly, the positive projection of the hot and cold medium channel 224 on the clamping surface of the heat conductive clamp 21 is a vortex line shape, the heating medium of the hot and cold medium channel 224 is hot air, the exhaust medium of the hot and cold medium channel 224 is compressed air, and the cooling medium of the hot and cold medium channel 224 is cold air.

[0061] Example 7: A method for freezing and peeling a wafer 11 disclosed in the present invention, which is different from Example 3 in that it includes the following steps:

[0062] S1 first drips 8 mL of a water-soluble medium 3 onto the surface of a pair of temperature-controlled clamps 2 through the injection channel 23. The water-soluble medium 3 is water. The pair of temperature-controlled clamps 2 are then separated, and the laser-modified 6-inch crystal ingot 1 is installed between the pair of temperature-controlled clamps 2. Then, pressure is continuously applied toward each other through the temperature-controlled clamps 2 to ensure that the crystal ingot 1 and the temperature-controlled clamps 2 are in complete contact through the water-soluble medium 3. The applied pressure is controlled to be 500 N. At the same time, the semiconductor refrigeration plate 221 on the temperature-controlled clamp 2 is started. The water-soluble medium 3 is cooled and solidified for 600 seconds under the action of the temperature-controlled clamp 2 and cooled to -10°C. The thickness of the water-soluble medium 3 after cooling and solidification is 70 to 80 μm, completing the bonding and fixation of the crystal ingot 1 between the pair of temperature-controlled clamps 2.

[0063] S2 first applies a reverse pulling force to the pair of temperature-controlled clamps 2 to move the temperature-controlled clamps 2 at a tensile speed of 2 mm / min until the peeling force reaches 1784 N and the modified layer 12 of the crystal ingot 1 is separated. After the peeling is completed, the semiconductor refrigeration plate 221 of the temperature-controlled clamp 2 switches the heating and cooling working surfaces by switching the positive and negative poles of the power supply, and heats the liquefied water-soluble medium 3 to remove the peeled wafer 11 and the remaining crystal ingot 13 from the temperature-controlled clamp 2. The removed wafer 11 is blown clean by an air gun and enters the next process.

[0064] Example 8: A method for freezing and peeling a wafer 11 disclosed in the present invention, which is different from Example 3 in that it includes the following steps:

[0065] S1 first drips 12mL of a water-soluble medium 3 on the surface of a pair of temperature-controlled clamps 2 through the injection channel 23. The water-soluble medium 3 is a 35v / v% Tween aqueous solution. Then, the pair of temperature-controlled clamps 2 are separated, and the laser-modified 6-inch crystal ingot 1 is installed between the pair of temperature-controlled clamps 2. Then, pressure is continuously applied to each other through the temperature-controlled clamps 2 to make the crystal ingot 1 and the temperature-controlled clamps 2 fully contact through the water-soluble medium 3. The applied pressure is controlled to be 50N. At the same time, the semiconductor refrigeration plate 221 on the temperature-controlled clamp 2 is started. The water-soluble medium 3 is cooled and solidified for 420s under the action of the temperature-controlled clamp 2 and cooled to -50°C. The thickness of the water-soluble medium 3 after cooling and solidification is 100-120μm, completing the bonding and fixation of the crystal ingot 1 between the pair of temperature-controlled clamps 2.

[0066] S2 first applies a reverse pulling force to the pair of temperature-controlled clamps 2 to move the temperature-controlled clamps 2 at a tensile speed of 5 mm / min until the peeling force reaches 2453 N and the modified layer 12 of the crystal ingot 1 is separated. After the peeling is completed, the semiconductor refrigeration plate 221 of the temperature-controlled clamp 2 switches the heating and cooling working surfaces by switching the positive and negative poles of the power supply, and heats the liquefied water-soluble medium 3 to remove the peeled wafer 11 and the remaining crystal ingot 13 from the temperature-controlled clamp 2. The removed wafer 11 is blown clean by an air gun and enters the next process.

[0067] Example 9: A method for freezing and peeling a wafer 11 disclosed in the present invention, which is different from Example 5 in that it includes the following steps:

[0068] S1 first drips 8 mL of a water-soluble medium 3 onto the surface of a pair of temperature-controlled clamps 2 through the injection channel 23. The water-soluble medium 3 is a 35 v / v% Tween aqueous solution. The pair of temperature-controlled clamps 2 are then separated, and the laser-modified 6-inch crystal ingot 1 is installed between the pair of temperature-controlled clamps 2. Then, pressure is continuously applied toward each other through the temperature-controlled clamps 2 to ensure that the crystal ingot 1 and the temperature-controlled clamps 2 are in full contact through the water-soluble medium 3. The applied pressure is controlled to be 800 N. At the same time, the semiconductor refrigeration plate 221 on the temperature-controlled clamp 2 is started. The water-soluble medium 3 is cooled and solidified for 120 seconds under the action of the temperature-controlled clamp 2 and cooled to -10°C. The thickness of the water-soluble medium 3 after cooling and solidification is 70 to 80 μm, completing the bonding and fixation of the crystal ingot 1 between the pair of temperature-controlled clamps 2.

[0069] S2 first applies a reverse pulling force to the pair of temperature-controlled clamps 2 to move the temperature-controlled clamps 2 at a tensile speed of 4 mm / min until the peeling force reaches 1867 N and the modified layer 12 of the crystal ingot 1 is separated. After the peeling is completed, the semiconductor refrigeration plate 221 of the temperature-controlled clamp 2 switches the heating and cooling working surfaces by switching the positive and negative poles of the power supply, and heats the liquefied water-soluble medium 3 to remove the peeled wafer 11 and the remaining crystal ingot 13 from the temperature-controlled clamp 2. The removed wafer 11 is blown clean by an air gun and enters the next process.

[0070] Example 10: A method for freezing and peeling a wafer 11 disclosed in the present invention, which is different from Example 6 in that it includes the following steps:

[0071] S1 first drips 20mL of a water-soluble medium 3 onto the surface of a pair of temperature-controlled clamps 2 through the injection channel 23. The water-soluble medium 3 is a 35v / v% Tween aqueous solution. The pair of temperature-controlled clamps 2 are then separated, and the laser-modified 6-inch crystal ingot 1 is installed between the pair of temperature-controlled clamps 2. Then, pressure is continuously applied toward each other through the temperature-controlled clamps 2 to ensure that the crystal ingot 1 and the temperature-controlled clamps 2 are in complete contact through the water-soluble medium 3. The applied pressure is controlled to be 300N. At the same time, the semiconductor refrigeration plate 221 on the temperature-controlled clamp 2 is started. The water-soluble medium 3 is cooled and solidified for 60s under the action of the temperature-controlled clamp 2 and cooled to -100°C. The thickness of the water-soluble medium 3 after cooling and solidification is 180-200μm, completing the bonding and fixation of the crystal ingot 1 between the pair of temperature-controlled clamps 2.

[0072] S2 first applies a reverse pulling force to the pair of temperature-controlled clamps 2 to move the temperature-controlled clamps 2 at a tensile speed of 0.1 mm / min until the peeling force reaches 2334 N and the modified layer 12 of the crystal ingot 1 is separated. After the peeling is completed, the semiconductor refrigeration plate 221 of the temperature-controlled clamp 2 switches the heating and cooling working surfaces by switching the positive and negative poles of the power supply, and heats the liquefied water-soluble medium 3 to remove the peeled wafer 11 and the remaining crystal ingot 13 from the temperature-controlled clamp 2. The removed wafer 11 is blown clean by an air gun and enters the next process.

[0073] Example 11: A method for freezing and peeling a wafer 11 disclosed in the present invention, which is different from Example 3 in that it includes the following steps:

[0074] S1 first drips 8 mL of a water-soluble medium 3 onto the surface of a pair of temperature-controlled clamps 2 through the injection channel 23. The water-soluble medium 3 is a 5 v / v% aqueous solution of a silane coupling agent. The pair of temperature-controlled clamps 2 are then separated, and the laser-modified 6-inch crystal ingot 1 is installed between the pair of temperature-controlled clamps 2. Then, pressure is continuously applied toward each other through the temperature-controlled clamps 2 to ensure that the crystal ingot 1 and the temperature-controlled clamps 2 are in complete contact through the water-soluble medium 3. The applied pressure is controlled to be 500 N. At the same time, the semiconductor refrigeration plate 221 on the temperature-controlled clamp 2 is started. The water-soluble medium 3 is cooled and solidified for 600 s under the action of the temperature-controlled clamp 2 and cooled to -10°C. The thickness of the water-soluble medium 3 after cooling and solidification is 70 to 80 μm, completing the bonding and fixation of the crystal ingot 1 between the pair of temperature-controlled clamps 2.

[0075] S2 first applies a reverse pulling force to the pair of temperature-controlled clamps 2 to move the temperature-controlled clamps 2 at a pulling speed of 2 mm / min until the peeling force is N and the modified layer 12 of the crystal ingot 1 is separated. After the peeling is completed, the semiconductor refrigeration plate 221 of the temperature-controlled clamp 2 switches the heating and cooling working surfaces by switching the positive and negative poles of the power supply, and heats the liquefied water-soluble medium 3 to remove the peeled wafer 11 and the remaining crystal ingot 13 from the temperature-controlled clamp 2. The removed wafer 11 is blown clean by an air gun and enters the next process.

[0076] Example 12: A method for freezing and peeling a wafer 11 disclosed in the present invention, which is different from Example 3 in that it includes the following steps:

[0077] S1 first drips 8 mL of a water-soluble medium 3 onto the surface of a pair of temperature-controlled clamps 2 through the injection channel 23. The water-soluble medium 3 is a 5 v / v% aqueous solution of polyacrylamide anions. The pair of temperature-controlled clamps 2 are then separated, and the laser-modified 6-inch crystal ingot 1 is installed between the pair of temperature-controlled clamps 2. Then, pressure is continuously applied toward each other through the temperature-controlled clamps 2 to ensure that the crystal ingot 1 and the temperature-controlled clamps 2 are in complete contact through the water-soluble medium 3. The applied pressure is controlled to be 500 N. At the same time, the semiconductor refrigeration plate 221 on the temperature-controlled clamp 2 is started. The water-soluble medium 3 is cooled and solidified for 600 s under the action of the temperature-controlled clamp 2 and cooled to -10°C. The thickness of the water-soluble medium 3 after cooling and solidification is 70 to 80 μm, completing the bonding and fixation of the crystal ingot 1 between the pair of temperature-controlled clamps 2.

[0078] S2 first applies a reverse pulling force to the pair of temperature-controlled clamps 2 to move the temperature-controlled clamps 2 at a pulling speed of 2 mm / min until the modified layer 12 of the ingot 1 is separated. After the peeling is completed, the semiconductor refrigeration plate 221 of the temperature-controlled clamp 2 switches the heating and cooling working surfaces by switching the positive and negative poles of the power supply, and heats the liquefied water-soluble medium 3 to remove the peeled wafer 11 and the remaining ingot 13 from the temperature-controlled clamp 2. The removed wafer 11 is blown clean by an air gun and enters the next process.

[0079] Example 13: A method for freezing and peeling a wafer 11 disclosed in the present invention, which is different from Example 3 in that it includes the following steps:

[0080] S1 first drips 8 mL of a water-soluble medium 3 onto the surface of a pair of temperature-controlled clamps 2 through the injection channel 23. The water-soluble medium 3 is a 5 v / v% aqueous solution of polyacrylamide cations. The pair of temperature-controlled clamps 2 are then separated, and the laser-modified 6-inch crystal ingot 1 is installed between the pair of temperature-controlled clamps 2. Then, pressure is continuously applied toward each other through the temperature-controlled clamps 2 to ensure that the crystal ingot 1 and the temperature-controlled clamps 2 are in complete contact through the water-soluble medium 3. The applied pressure is controlled to be 500 N. At the same time, the semiconductor refrigeration plate 221 on the temperature-controlled clamp 2 is started. The water-soluble medium 3 is cooled and solidified for 600 s under the action of the temperature-controlled clamp 2 and cooled to -10°C. The thickness of the water-soluble medium 3 after cooling and solidification is 70 to 80 μm, completing the bonding and fixation of the crystal ingot 1 between the pair of temperature-controlled clamps 2.

[0081] S2 first applies a reverse pulling force to the pair of temperature-controlled clamps 2 to move the temperature-controlled clamps 2 at a pulling speed of 2 mm / min until the modified layer 12 of the ingot 1 is separated. After the peeling is completed, the semiconductor refrigeration plate 221 of the temperature-controlled clamp 2 switches the heating and cooling working surfaces by switching the positive and negative poles of the power supply, and heats the liquefied water-soluble medium 3 to remove the peeled wafer 11 and the remaining ingot 13 from the temperature-controlled clamp 2. The removed wafer 11 is blown clean by an air gun and enters the next process.

[0082] Example 14: A method for freezing and peeling a wafer 11 disclosed in the present invention, which is different from Example 3 in that it includes the following steps:

[0083] S1 first drips 8 mL of a water-soluble medium 3 onto the surface of a pair of temperature-controlled clamps 2 through the injection channel 23. The water-soluble medium 3 is a 5 v / v% carboxymethyl cellulose aqueous solution. The pair of temperature-controlled clamps 2 are then separated, and the laser-modified 6-inch crystal ingot 1 is installed between the pair of temperature-controlled clamps 2. Then, pressure is continuously applied toward each other through the temperature-controlled clamps 2 to ensure that the crystal ingot 1 and the temperature-controlled clamps 2 are in complete contact through the water-soluble medium 3. The applied pressure is controlled to be 500 N. At the same time, the semiconductor refrigeration plate 221 on the temperature-controlled clamp 2 is started. The water-soluble medium 3 is cooled and solidified for 600 s under the action of the temperature-controlled clamp 2 and cooled to -10°C. The thickness of the water-soluble medium 3 after cooling and solidification is 70 to 80 μm, completing the bonding and fixation of the crystal ingot 1 between the pair of temperature-controlled clamps 2.

[0084] S2 first applies a reverse pulling force to the pair of temperature-controlled clamps 2 to move the temperature-controlled clamps 2 at a pulling speed of 2 mm / min until the modified layer 12 of the ingot 1 is separated. After the peeling is completed, the semiconductor refrigeration plate 221 of the temperature-controlled clamp 2 switches the heating and cooling working surfaces by switching the positive and negative poles of the power supply, and heats the liquefied water-soluble medium 3 to remove the peeled wafer 11 and the remaining ingot 13 from the temperature-controlled clamp 2. The removed wafer 11 is blown clean by an air gun and enters the next process.

[0085] Comparative Example

[0086] Comparative Example 1: A wafer cryo-peeling method disclosed in the present invention, which differs from Example 4 in that thermoplastic glue is used instead of the water-soluble medium solution.

[0087] Comparative Example 2: A wafer cryo-peeling method disclosed in the present invention, which differs from Example 4 in that paraffin is used instead of the water-soluble medium solution.

[0088] Comparative Example 3: A wafer cryo-peeling method disclosed in the present invention, which differs from Example 4 in that a suction cup vacuum adsorption stretching peeling is used instead of a temperature-controlled clamp and a water-soluble medium solution stretching peeling.

[0089] Comparative Example 4: A wafer cryo-peeling method disclosed in the present invention is different from Example 4 in that a water-soluble medium solution is used to infiltrate the modified layer and then freeze-expand and separate instead of temperature-controlled clamps and water-soluble medium solution stretching and peeling.

[0090] Performance testing

[0091] (1) The wafers obtained by peeling Example 4 and Comparative Examples 1 to 4 were tested for bonding time, peeling force, wafer integrity, cleaning method, and cleaning time. The test results are shown in Table 1.

[0092] Table 1

[0093] As can be seen from Table 1, the water-ice bonding solution has a bonding strength that is close to the peeling strength of the adhesive and wax bonding solutions, and has a higher peeling efficiency and is relatively easy to clean. However, the vacuum suction cup solution has a limited peeling force that is insufficient to successfully peel the wafer, and the frozen expansion solution is more convenient but prone to fragmentation.

[0094] (2) The methods of Examples 7 and 11 to 14 were used to test the pull-off forces of 6-inch wafers after freezing at different temperatures using different aqueous media solutions. The test results are shown in Table 2.

[0095] Table 2

[0096] As can be seen from Table 2, as the cooling temperature of the refrigerant decreases, the bonding force is significantly enhanced. In addition, the bonding force between the fixture and the wafer can be significantly improved by activating and modifying the aqueous solution. Among them, the addition of silane coupling agent has increased the bonding force with the polyacrylamide anion aqueous solution to the maximum.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A wafer cryo-peeling method, characterized in that: The following steps are included: S1: After a liquid water-soluble medium is coated on the end surface of the ingot and / or the clamping surface of the temperature control clamp, the water-soluble medium is cooled and solidified under the action of the temperature control clamp, thereby completing the fixing of the ingot between a pair of temperature control clamps; S2 moves at least one temperature-controlled fixture until the modified layer of the ingot is separated. After the stripping is completed, the solid water-soluble medium is heated and liquefied under the action of the temperature-controlled fixture to obtain a wafer and a remaining ingot.

2. A wafer cryo-peeling method according to claim 1, characterized in that: In S1, the water-soluble medium is one or a combination of water, water-soluble organic matter and water-soluble inorganic matter.

3. A wafer cryo-peeling method according to claim 2, characterized in that: In S1, the freezing point of the water-soluble medium is -50 to 80°C, and the dynamic viscosity at room temperature and pressure is 1.01×10 -3 ~100Pa·s.

4. A wafer cryo-peeling method according to claim 2, characterized in that: In the above S1, in the composition of water, water-soluble organic matter and / or water-soluble inorganic matter, the volume concentration of each water-soluble organic matter and each water-soluble inorganic matter in the composition is independently 0.5 to 35%.

5. A wafer cryo-peeling method according to claim 2, characterized in that: In S1, the water-soluble medium is one or a combination of water, a silane coupling agent, anionic polyacrylamide, cationic polyacrylamide, carboxymethyl cellulose and a surfactant.

6. A wafer cryo-peeling method according to claim 1, characterized in that: In S1, the pressure applied by the temperature control fixture to the water-soluble medium during cooling and solidification is controlled to be 1 to 3000 N, the cooling temperature is 1 to 40° C. lower than the solidification point of the water-soluble medium, the cooling time is 10 to 600 s, and the amount of the water-soluble medium is controlled to be 0.1 to 20 mL, and the thickness after cooling and solidification is 20 to 200 μm.

7. A wafer cryo-peeling method according to claim 1, characterized in that: In S1, the coating method of the water-soluble medium is one or a combination of drip coating, spin coating, scraper coating, spray coating, brush coating, roll coating, dip coating, and transfer coating using an absorbent material adsorbed with the water-soluble medium.

8. A wafer cryo-peeling method according to claim 1, characterized in that: In S2, the moving stretching speed of the temperature-controlled clamp is controlled to be 0.01 to 5.00 mm / min.

9. A wafer cryo-peeling method according to claim 1, characterized in that: The temperature control clamp includes a heat-conducting clamp seat, a cooling and heating module arranged on the heat-conducting clamp seat, and a plurality of temperature detection modules. The cooling and heating module cools or heats in a manner of diffusing from the central area of ​​the heat-conducting clamp seat to the peripheral area. The temperature detection modules are installed on the heat-conducting clamp seat with the detection end facing the clamping surface, and are arranged sequentially along the diffusion path of the cooling and heating module.

10. A wafer cryo-peeling method according to claim 9, characterized in that: The diffusion path of the cooling and heating module is one or a combination of a row-by-row diffusion path, a grid-interlaced diffusion path, a concentric circle diffusion path and a vortex line diffusion path.

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