Wafer freezing stripping method

Abstract

The invention relates to a wafer freezing stripping method, which comprises the following steps that: after the end surface of a crystal ingot and / or the clamping surface of a temperature control clamp is coated with a liquid water-soluble medium, the water-soluble medium is cooled and solidified under the action of the temperature control clamp, and the crystal ingot is fixed between a pair of temperature control clamps; and at least one temperature control clamp is moved until the modified layer of the crystal ingot is separated, and after stripping is finished, the solid water-soluble medium is heated and liquefied under the action of the temperature control clamp to obtain the wafer and the residual crystal ingot. The method has the advantages of high stripping efficiency, cleaning procedure saving, convenience in stripping condition control, low cracking risk, simplicity in operation and suitability for large-scale industrial application.

Description

Technical Field

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

[0002] At present, the most advanced chip manufacturing process requires nearly 4,000 processes, which mainly include wafer processing (raw materials-ingot-wafer), wafer manufacturing (front-end process, including) deposition, lithography, etching, ion implantation and metallization, and packaging and testing (back-end process), including cutting, die bonding, etc. Benefiting from its applicability in cutting, drilling, welding, etc., laser mainly provides 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 and loss on materials, and is therefore more suitable for cutting high-hardness, high-brittle materials such as SiC wafers (third-generation semiconductors). At present, after laser processing and modification below the surface of the ingot, 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, and it is also necessary to ensure the simplicity of cleaning the wafer in the cleaning process after peeling to remove the contamination of the previous process and create conditions for the next process.

[0004] The Chinese patent with the authorization announcement number CN115410979B applied by the applicant recently discloses a method for peeling wafers. For the wafers modified by laser processing, the sample to be peeled is bonded with a hot-melt adhesive and then the wafer is peeled. In addition, the Chinese patent with the publication number CN113972160A discloses a laser slicing method for solid materials, which uses laser to form a peeling surface inside the solid material; by preheating the thermoplastic glue to the glass transition temperature, and then applying it to the surface of the solid material in a heated state, and then naturally cooling it to generate stress cracks with the help of the difference in thermal expansion coefficients to obtain a thin layer of wafer. The surface of the wafer peeled by the thermoplastic glue or hot-melt adhesive used in the above method will have residual adhesive, which needs to be cleaned in another process, and cannot directly enter the thinning and polishing process.

[0005] The Chinese patent with publication number CN115138987A discloses a method for peeling silicon carbide wafers, which heats and cools the thick and thin layers of silicon carbide after laser processing, respectively, so that a temperature difference is formed between the thin and thick layers, destroying the physical connection between the thin and thick layers, and then peeling the thick and thin layers. At the same time, the Chinese patent with publication number CN115513043A discloses a method for peeling a wafer from a silicon carbide ingot, which injects a pre-prepared liquid into the modified layer of the silicon carbide ingot through ultrasonic vibration, and after the liquid fills the modified layer, the silicon carbide ingot filled with the liquid is cooled until the liquid freezes and causes the modified layer to expand and break, and the wafer layer is 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, and silicon carbide wafers are at a greater risk of breakage as hard and brittle materials, and this solution is difficult to implement in an automated production line.

[0006] The Chinese patent with publication number CN111106032A discloses a wafer generation device, which positions the focal point of a laser beam with a wavelength that is transparent to the crystal ingot at a depth from the upper surface of the crystal ingot that is equivalent to the thickness of the wafer to be generated, and irradiates the crystal ingot with laser beams to form a peeling layer; then the wafer is peeled off 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 off the wafer. When the above device applies ultrasonic action, if the cracks inside the peeling layer are not uniform and flat enough, the ultrasonic time needs to be extended. There is a lack of standards that can evaluate whether the peeling strength has been lower than the suction cup adsorption force. In addition, it is difficult to peel when the ultrasonic action fails to reduce the strength of the peeling layer to below the suction cup adsorption force. Moreover, applying ultrasonic action in a liquid environment will increase the complexity of the device and there is a risk of liquid leakage.

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

[0008] The problem to be solved by the present invention is to provide a wafer freezing peeling method in view of the above-mentioned deficiencies in the prior art, which has the advantages of high peeling efficiency, saving cleaning process, easy to control peeling conditions, low risk of cracking, simple operation, and suitability for large-scale industrial applications.

[0009] The above-mentioned object of the present invention is achieved through the following technical solutions:

[0010] A wafer cryo-peeling method comprises the following steps:

[0011] 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;

[0012] 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.

[0013] Further, in S1, the water-soluble medium is a combination of one or more of water, water-soluble organic matter and water-soluble inorganic matter. The above-mentioned several compositions are specifically a composition of at least two water-soluble organic matter, a composition of at least two water-soluble inorganic matter, a composition of water and several water-soluble organic matter, a composition of water and several water-soluble inorganic matter, a composition of several water-soluble organic matter and several water-soluble inorganic matter, or a composition of water, several water-soluble organic matter and several water-soluble inorganic matter.

[0014] Furthermore, 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.

[0015] 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.

[0016] Furthermore, in the 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 0.5-35%. Wherein, 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.

[0017] Preferably, 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, 0.8, 1.0, 5, 10, 15, 20, 25, 30 or 35%.

[0018] Furthermore, 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.

[0019] Further, in the S1, the coating method of the water-soluble medium is drip coating, spin coating, scraping coating, spray coating, brush coating, roll coating, dip coating, and a combination of one or more of the following coating methods: transfer coating using an absorbent 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 control 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 control fixture by spin coating / scraping coating / spraying / brushing / roll coating / dip coating, etc., and / or transferred and coated on the end face of the ingot and / or the clamping surface of the temperature control fixture by means of an absorbent material, and the water-soluble medium is forced to diffuse by applying pressure through the temperature control fixture, and evenly distributed between the end face of the ingot and the clamping surface of the temperature control fixture, or between the clamping surfaces of the pair of temperature control fixtures, to complete the coating of the water-soluble medium on the end face of the ingot and / or the clamping surface of the temperature control fixture.

[0020] Furthermore, in S1, the pressure applied by the temperature control fixture to the water-soluble medium during cooling and solidification is controlled to be 1~3000N, the cooling temperature is 1~40°C lower than the solidification point of the water-soluble medium, the cooling time is 10~600s, and the amount of the water-soluble medium is controlled to be 0.1~20mL, and the thickness after cooling and solidification is 20~200μm.

[0021] Preferably, in S1, the pressure applied by the temperature control fixture to the water-soluble medium during cooling and curing 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, 1600, 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°C below the freezing point of the water-soluble medium, and the 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 the amount of water-soluble medium is controlled to be 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.

[0022] Furthermore, in S2, the moving stretching speed of the temperature-controlled clamp is controlled to be 0.01-5.00 mm / min.

[0023] Furthermore, 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 performs cooling or heating in a manner of diffusing from a central area of ​​the heat-conducting clamp seat to a peripheral area. These 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.

[0024] Furthermore, the temperature control fixture also includes a plurality of injection channels opened on the thermally conductive clamp seat, wherein the liquid inlet of the injection channel is used to receive the water-soluble medium, and the liquid outlet is arranged on the clamping surface of the thermally conductive clamp seat.

[0025] Furthermore, the diffusion path of the cooling and heating module is a row-by-row diffusion path, a grid-interlaced diffusion path, a concentric circle diffusion path, and a vortex line diffusion path, or a combination of the two.

[0026] Furthermore, the cooling and heating module includes a plurality of semiconductor cooling sheets arranged along the diffusion path. Among them, the semiconductor cooling sheet, also called the thermoelectric cooling sheet, is a heat pump, which has the advantage of having no sliding parts and can be applied to some occasions where space is limited, reliability is high, and there is no refrigerant pollution. It uses the Peltier effect of semiconductor materials. When direct current passes through a thermocouple formed by two different semiconductor materials in series, heat can be absorbed and released at both ends of the thermocouple respectively, so as to achieve the purpose of cooling and heating; the semiconductor cooling sheet can be a square with a size ranging from 10mm*10mm to 60mm*60mm, and is evenly distributed horizontally on the thermal conductive clamp. In order to further improve the cooling effect of the semiconductor cooling sheet, at least two semiconductor cooling sheets can be arranged in a superimposed manner.

[0027] Preferably, a water-cooling block is provided on the side of the semiconductor cooling plate away from the clamping surface of the heat-conducting clamp seat through conductive silver paste. The water-cooling block is a metal block made of copper or aluminum with a water channel inside. To ensure the heat dissipation effect, a single water-cooling block is connected to a water chiller through a liquid injection hole for cooling. Compared with the water-cooling block series connection, this parallel connection method will make the water-cooling temperature of the semiconductor cooling plate tend to be consistent, thereby ensuring the cooling effect.

[0028] Preferably, a heat dissipation channel is provided on the side of the semiconductor cooling sheet away from the clamping surface of the heat conducting clamp seat through heat conducting silicone grease, and the flow path of the cooling medium in the heat dissipation channel passes through the semiconductor cooling sheets in sequence from the inside to the outside. The orthographic projection of the heat dissipation channel on the clamping surface of the heat conducting clamp seat is a spiral line shape, which ensures that the semiconductor cooling sheet dissipates heat evenly, and the cooling medium of the heat dissipation channel is a coolant or cold air with a freezing point below -50°C.

[0029] 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 orthographic projection of the hot and cold medium channel on the clamping surface of the thermal clamp is a spiral line.

[0030] 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.

[0031] Furthermore, the temperature detection modules are temperature sensors, which are used to detect the temperature of each area from the central area to the peripheral area of ​​the thermal clamp to control the temperature difference of the clamping surface of the temperature control fixture within ±2°C. The temperature sensor is not limited to, for example, a contact temperature sensor, preferably a PT100 temperature sensor, and the PT100 temperature sensor is in contact with the inside of the temperature control fixture through thermal grease.

[0032] In summary, the beneficial technical effects of the present invention are:

[0033] 1. In the stripping method of the present invention, the water-soluble medium is cooled to a temperature below the freezing point by a temperature-controlled fixture, so that the freezing effect of cooling and solidification can be achieved, and the wafer can be directly stretched and stripped. After stripping, the water-soluble medium is reheated to above the freezing point, and the wafer can be quickly taken out. The surface of the wafer after stripping only needs to be simply purged to remove the water-soluble medium, and then the next thinning process can be entered. The thinning process itself will be flushed with water, and the water-soluble medium will dissolve and disappear during the flushing process. Compared with the gluing or waxing method, the cleaning process is omitted, and the operation is more convenient;

[0034] 2. In the peeling process of the peeling method of the present invention, since the thermal conductivity of the wafer is generally good, the wafer to be peeled can be frozen by cooling one side directly. In addition, the water-soluble medium has good fluidity. The temperature-controlled fixture is pressed down on the surface of the wafer to force the water-soluble medium to be evenly distributed. The surface to be peeled and the surface of the temperature-controlled fixture are completely in contact, and there will be no problem of uneven force causing fragmentation;

[0035] 3. During the stripping process of the stripping 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 stripped is much greater than the theoretical suction force (0.1 MPa) of a vacuum chuck, etc., and the separation of wafers with a large stripping force can be completed without the need for complex auxiliary stripping equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the connection relationship between the temperature control fixture and the crystal ingot in Example 1 of the present invention.

[0037] Figure 2 It is a schematic diagram of the structure of the temperature control fixture of Example 2 of the present invention.

[0038] Figure 3 It is a schematic diagram of the structure of the temperature control fixture of Example 5 of the present invention.

[0039] Figure 4 It is a schematic diagram of the structure of the temperature control fixture of Example 6 of the present invention.

[0040] In the figure, 1. ingot; 11. wafer; 12. modified layer; 13. remaining ingot; 2. temperature control fixture; 21. thermal conductive clamp; 22. cooling and heating module; 221. semiconductor cooling plate; 222. liquid inlet; 223. liquid outlet; 224. cold and hot medium channels; 23. liquid injection channel; 24. temperature detection module; 25. water cooling block; 26. heat dissipation channel; 3. water-soluble medium. DETAILED DESCRIPTION

[0041] 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 in conjunction with the accompanying drawings and specific implementation methods.

[0042] Example

[0043] Example 1: Reference Figure 1 , a wafer 11 cryo-peeling method disclosed in the present invention comprises the following steps:

[0044] S1: After coating the end surface 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 fixing of the crystal ingot 1 between a pair of temperature control clamps 2;

[0045] S2 moves at least one temperature-controlled fixture 2 until the modified layer 12 of the crystal 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 fixture 2 to obtain a wafer 11 and a remaining crystal ingot 13.

[0046] 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 -50~80℃, 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 0.5-35%, and the water-soluble medium 3 can preferably be a combination of one or more of water, silane coupling agent, anionic polyacrylamide, cationic polyacrylamide, carboxymethyl cellulose and surfactant.

[0047] At the same time, the coating method of the water-soluble medium 3 is one or more of drip coating, spin coating, scraping coating, spray coating, brush coating, roll coating, dip coating, 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 control fixture 2, directly coated on the end face of the ingot 1 and / or the clamping surface of the temperature control fixture 2 by spin coating / scraping coating / spraying / brushing / roll coating / dip coating, and / or transferred and coated on the end face of the ingot 1 and / or the clamping surface of the temperature control fixture 2 by means of an absorbent material, and the water-soluble medium 3 is also forced to diffuse by the temperature control fixture 2, and evenly distributed between the end face of the ingot 1 and the clamping surface of the temperature control fixture 2, or between the clamping surfaces of the pair of temperature control fixtures 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 control fixture 2.

[0048] 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.

[0049] Finally, in S2 , by controlling the moving 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.

[0050] Example 2: Reference Figure 1 and Figure 2 , which is a wafer 11 freezing peeling method disclosed in the present invention. The difference from Example 1 is that the temperature control clamp 2 includes a thermally conductive clamp 21, a cooling and heating module 22 arranged on the thermally conductive clamp 21, a plurality of injection channels 23 opened on the thermally conductive clamp 21, and a plurality of temperature detection modules 24.

[0051] Among them, the cooling and heating module 22 performs cooling or heating 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 a row diffusion path, a grid interlaced diffusion path, a concentric circle diffusion path and a vortex line diffusion path.

[0052] These injection channels 23 can be arranged on one of the temperature control clamps 2, or on two temperature control clamps 2 respectively. In this embodiment, they are preferably arranged 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 arranged 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, 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.

[0053] These temperature detection modules 24 are installed on the thermal clamp 21 with the detection end facing the clamping surface, and are arranged in sequence along the diffusion path of the cooling and heating module 22. The temperature detection modules 24 are temperature sensors, which are used to detect the temperature of each area from the central area to the peripheral area of ​​the thermal clamp 21 to control the temperature difference of the clamping surface of the temperature control fixture 2 within ±2°C. Among them, the temperature sensor is not limited to, for example, a contact temperature sensor, preferably a PT100 temperature sensor, and the PT100 temperature sensor is in contact with the inside of the temperature control fixture 2 through thermal grease.

[0054] Example 3: Reference Figure 2 , which is a wafer 11 freezing and peeling method disclosed in the present invention. The difference from Example 2 is that the diffusion path of the cooling and heating module 22 is a concentric circle 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.

[0055] In order to improve the cooling effect, a water cooling block 25 is provided on the side of the conductor cooling sheet away from the clamping surface of the heat conducting clamp seat 21 through a conductive silver paste. The water cooling block 25 is a metal block made of copper or aluminum with a water channel inside. To ensure the heat dissipation effect, a single water cooling block 25 is connected to a water chiller through a liquid injection hole for cooling. Compared with the water cooling block 25 connected in series, this parallel connection makes the water cooling temperature of the semiconductor cooling sheet 221 tend to be consistent, thereby ensuring the cooling effect.

[0056] Embodiment 4 is a wafer 11 cryo-peeling method disclosed in the present invention. The difference from Embodiment 3 is that, in order to further improve the cooling effect of the semiconductor cooling sheet 221, two semiconductor cooling sheets 221 are arranged in a stacked manner.

[0057] Example 5: Reference Figure 3, which is a wafer 11 freezing peeling method disclosed in the present invention, is different from Example 3 in that, in order to improve the cooling effect, a heat dissipation channel 26 is provided on the side of the semiconductor cooling sheet 221 away from the clamping surface of the heat conducting clamp 21 through thermal grease, and the flow path of the cooling medium in the heat dissipation channel 26 passes through these semiconductor cooling sheets 221 in sequence from the inside to the outside. Among them, the positive projection of the heat dissipation channel 26 on the clamping surface of the heat conducting clamp 21 is a spiral line shape, which ensures that the semiconductor cooling sheet 221 dissipates heat evenly, and the cooling medium of the heat dissipation channel 26 is cold air.

[0058] Example 6: Reference Figure 4 , which is a wafer 11 freezing peeling method disclosed in the present invention. The difference from Example 2 is 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 cold and hot medium channel 224 arranged between the liquid inlet 222 and the liquid outlet 223.

[0059] Correspondingly, the positive projection of the hot and cold medium channel 224 on the clamping surface of the heat conductive clamp 21 is a spiral 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.

[0060] Embodiment 7: A method for freezing and peeling a wafer 11 disclosed in the present invention is different from Embodiment 3 in that it includes the following steps:

[0061] S1 first drips 8 mL 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 water. 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, the temperature-controlled clamps 2 continuously apply pressure in opposite directions so that the crystal ingot 1 and the temperature-controlled clamps 2 are completely in contact through the water-soluble medium 3. The applied pressure is controlled to be 500N. At the same time, the semiconductor refrigeration sheet 221 on the temperature-controlled clamps 2 is started. The water-soluble medium 3 is cooled and solidified for 600s under the action of the temperature-controlled clamps 2 and cooled to -10°C. The thickness of the water-soluble medium 3 after cooling and solidification is 70-80μm, and the bonding and fixing of the crystal ingot 1 between the pair of temperature-controlled clamps 2 is completed.

[0062] S2 first applies a reverse pulling force to the pair of temperature-controlled clamps 2 to make the temperature-controlled clamps 2 move 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 cleaned by an air gun and enters the next process.

[0063] Embodiment 8: A wafer 11 cryo-peeling method disclosed in the present invention, which is different from Embodiment 3 in that it includes the following steps:

[0064] 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, the temperature-controlled clamps 2 continuously apply pressure in opposite directions so that the crystal ingot 1 and the temperature-controlled clamps 2 are completely in contact through the water-soluble medium 3. The applied pressure is controlled to be 50N. At the same time, the semiconductor refrigeration sheet 221 on the temperature-controlled clamps 2 is started. The water-soluble medium 3 is cooled and solidified for 420s under the action of the temperature-controlled clamps 2 and cooled to -50°C. The thickness of the water-soluble medium 3 after cooling and solidification is 100~120μm, and the bonding and fixing of the crystal ingot 1 between the pair of temperature-controlled clamps 2 is completed.

[0065] S2 first applies a reverse pulling force to the pair of temperature-controlled clamps 2 to make the temperature-controlled clamps 2 move 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 cleaned by an air gun and enters the next process.

[0066] Embodiment 9 is a method for freezing and peeling a wafer 11 disclosed in the present invention, which is different from Embodiment 5 in that it includes the following steps:

[0067] S1 first drips 8mL of 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, and then separates the pair of temperature-controlled clamps 2, and installs the laser-modified 6-inch crystal ingot 1 between the pair of temperature-controlled clamps 2, and then continuously applies pressure in opposite directions through the temperature-controlled clamps 2 to make the crystal ingot 1 and the temperature-controlled clamps 2 completely contact through the water-soluble medium 3. The applied pressure is controlled to be 800N, and the semiconductor refrigeration sheet 221 on the temperature-controlled clamps 2 is started at the same time. The water-soluble medium 3 is cooled and solidified for 120s under the action of the temperature-controlled clamps 2, and is cooled to -10°C. The thickness of the water-soluble medium 3 after cooling and solidification is 70~80μm, and the bonding and fixing of the crystal ingot 1 between the pair of temperature-controlled clamps 2 is completed;

[0068] S2 first applies a reverse pulling force to the pair of temperature-controlled clamps 2 to make the temperature-controlled clamps 2 move 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 cleaned by an air gun and enters the next process.

[0069] Embodiment 10: A method for freezing and peeling a wafer 11 disclosed in the present invention, which is different from Embodiment 6 in that it includes the following steps:

[0070] S1 first drips 20mL 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, the temperature-controlled clamps 2 continuously apply pressure in opposite directions so 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 300N. At the same time, the semiconductor refrigeration sheet 221 on the temperature-controlled clamps 2 is started. The water-soluble medium 3 is cooled and solidified for 60s under the action of the temperature-controlled clamps 2 and cooled to -100°C. The thickness of the water-soluble medium 3 after cooling and solidification is 180~200μm, and the bonding and fixing of the crystal ingot 1 between the pair of temperature-controlled clamps 2 is completed.

[0071] S2 first applies a reverse pulling force to the pair of temperature control clamps 2 to make the temperature control clamps 2 move 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 control 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 control clamp 2. The removed wafer 11 is cleaned by an air gun and enters the next process.

[0072] Embodiment 11 is a wafer 11 cryo-peeling method disclosed in the present invention, which is different from Embodiment 3 in that it includes the following steps:

[0073] S1 first drips 8mL of 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 5v / v% aqueous solution of silane coupling agent. 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, the temperature-controlled clamps 2 continuously apply pressure in opposite directions so that the crystal ingot 1 and the temperature-controlled clamps 2 are completely in contact through the water-soluble medium 3. The applied pressure is controlled to be 500N. At the same time, the semiconductor refrigeration sheet 221 on the temperature-controlled clamps 2 is started. The water-soluble medium 3 is cooled and solidified for 600s under the action of the temperature-controlled clamps 2 and cooled to -10°C. The thickness of the water-soluble medium 3 after cooling and solidification is 70~80μm, and the bonding and fixing of the crystal ingot 1 between the pair of temperature-controlled clamps 2 is completed.

[0074] S2 first applies a reverse pulling force to the pair of temperature-controlled clamps 2 to make the temperature-controlled clamps 2 move at a tensile 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, so that the peeled wafer 11 and the remaining crystal ingot 13 can be removed from the temperature-controlled clamp 2. The removed wafer 11 is blown clean by an air gun and enters the next process.

[0075] Embodiment 12 is a method for freezing and peeling a wafer 11 disclosed in the present invention, which is different from Embodiment 3 in that it includes the following steps:

[0076] S1 first drips 8mL of 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 5v / v% aqueous solution of polyacrylamide anions. 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, the temperature-controlled clamps 2 continuously apply pressure in opposite directions so that the crystal ingot 1 and the temperature-controlled clamps 2 are completely in contact through the water-soluble medium 3. The applied pressure is controlled to be 500N. At the same time, the semiconductor refrigeration sheet 221 on the temperature-controlled clamps 2 is started. The water-soluble medium 3 is cooled and solidified for 600s under the action of the temperature-controlled clamps 2 and cooled to -10°C. The thickness of the water-soluble medium 3 after cooling and solidification is 70~80μm, and the bonding and fixing of the crystal ingot 1 between the pair of temperature-controlled clamps 2 is completed.

[0077] S2 first applies a reverse pulling force to the pair of temperature control clamps 2 to make the temperature control clamps 2 move at a pulling speed of 2 mm / min until the modified layer 12 of the crystal ingot 1 is separated. After the peeling is completed, the semiconductor refrigeration plate 221 of the temperature control 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, so that the peeled wafer 11 and the remaining crystal ingot 13 can be removed from the temperature control clamp 2. The removed wafer 11 is blown clean by an air gun and enters the next process.

[0078] Embodiment 13: A wafer 11 cryo-peeling method disclosed in the present invention, which is different from Embodiment 3 in that it includes the following steps:

[0079] S1 first drips 8mL of 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 5v / v% aqueous solution of polyacrylamide cations, and then separates the pair of temperature-controlled clamps 2, and installs the laser-modified 6-inch crystal ingot 1 between the pair of temperature-controlled clamps 2, and then continuously applies pressure in opposite directions through the temperature-controlled clamps 2 to make the crystal ingot 1 and the temperature-controlled clamps 2 completely contact through the water-soluble medium 3. The applied pressure is controlled to be 500N, and the semiconductor refrigeration plate 221 on the temperature-controlled clamps 2 is started at the same time. The water-soluble medium 3 is cooled and solidified for 600s under the action of the temperature-controlled clamps 2, and is cooled to -10°C. The thickness of the water-soluble medium 3 after cooling and solidification is 70~80μm, and the bonding and fixing of the crystal ingot 1 between the pair of temperature-controlled clamps 2 is completed;

[0080] S2 first applies a reverse pulling force to the pair of temperature control clamps 2 to make the temperature control clamps 2 move at a pulling speed of 2 mm / min until the modified layer 12 of the crystal ingot 1 is separated. After the peeling is completed, the semiconductor refrigeration plate 221 of the temperature control 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, so that the peeled wafer 11 and the remaining crystal ingot 13 can be removed from the temperature control clamp 2. The removed wafer 11 is blown clean by an air gun and enters the next process.

[0081] Embodiment 14 is a method for freezing and peeling a wafer 11 disclosed in the present invention, which is different from Embodiment 3 in that it includes the following steps:

[0082] S1 first drips 8 mL 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 5 v / v% carboxymethyl cellulose aqueous solution, and then separates the pair of temperature-controlled clamps 2, and installs the laser-modified 6-inch crystal ingot 1 between the pair of temperature-controlled clamps 2. Then, the temperature-controlled clamps 2 continuously apply pressure in opposite directions so that the crystal ingot 1 and the temperature-controlled clamps 2 are completely in contact through the water-soluble medium 3. The applied pressure is controlled to be 500 N, and the semiconductor refrigeration sheet 221 on the temperature-controlled clamps 2 is started at the same time. The water-soluble medium 3 is cooled and solidified for 600 s under the action of the temperature-controlled clamps 2, and is cooled to -10°C. The thickness of the water-soluble medium 3 after cooling and solidification is 70-80 μm, and the bonding and fixing of the crystal ingot 1 between the pair of temperature-controlled clamps 2 is completed;

[0083] S2 first applies a reverse pulling force to the pair of temperature control clamps 2 to make the temperature control clamps 2 move at a pulling speed of 2 mm / min until the modified layer 12 of the crystal ingot 1 is separated. After the peeling is completed, the semiconductor refrigeration plate 221 of the temperature control 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, so that the peeled wafer 11 and the remaining crystal ingot 13 can be removed from the temperature control clamp 2. The removed wafer 11 is blown clean by an air gun and enters the next process.

[0084] Comparative Example

[0085] Comparative Example 1 is a wafer cryo-peeling method disclosed in the present invention, which is different from Example 4 in that thermoplastic glue is used instead of the water-soluble medium solution.

[0086] Comparative Example 2 is a wafer cryo-peeling method disclosed in the present invention, which is different from Example 4 in that paraffin is used instead of the water-soluble medium solution.

[0087] Comparative Example 3 is a wafer freezing peeling method disclosed in the present invention, which is different 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.

[0088] Comparative Example 4: A wafer cryo-peeling method disclosed in the present invention, which differs 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.

[0089] Performance testing

[0090] (1) The wafers obtained by peeling off 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.

[0091] Table 1

[0092] Stripping method Bonding time Peel force Is the wafer complete? Cleaning method Cleaning time Example 7 Water ice bonding 2min 3619N yes Air gun cleaning 10s Comparative Example 1 Adhesive peeling 15min 3875N yes Glue dissolving agent 1h+ Comparative Example 2 Wax peeling 5min 3156N no Anhydrous ethanol 5min Comparative Example 3 Suction cup adsorption 5s 1384N Unseparated - - Comparative Example 4 Liquid expansion 5min - no Washing 10s

[0093] As can be seen from Table 1, the bonding force of the water-ice bonding scheme can also reach a peeling force close to that of the adhesive and wax bonding schemes, and the peeling efficiency is higher and the cleaning is more convenient; while the peeling force of the vacuum suction cup scheme is limited and is not enough to successfully peel off the chip, and although the frozen expansion scheme is more convenient, it is prone to fragmentation.

[0094] (2) The methods of Example 7 and Examples 11 to 14 were used to test the pull-off force of a 6-inch wafer after freezing the water-soluble medium solution at different temperatures. The test results are shown in Table 2.

[0095] Table 2

[0096] -40℃ Pull-off force (N) -30℃ Pull-off force (N) -20℃ Pull-off force (N) -10℃ Pull-off force (N) Example 7 6183 4561 2573 1784 Embodiment 11 13074 10245 8468 4541 Example 12 11971 9283 6234 3538 Embodiment 13 4752 3248 2357 1145 Embodiment 14 8051 6776 5433 3143

[0097] It can be seen from Table 2 that with the decrease of cooling temperature, the bonding strength of the water-soluble medium solution after freezing the 6-inch wafer is significantly enhanced. In addition, the bonding strength between the fixture and the wafer can be significantly improved by activating and modifying the aqueous solution. Among them, the aqueous solution with added silane coupling agent and the aqueous solution with polyacrylamide anion have the largest bonding strength.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. 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 solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should 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 -50~80°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 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 1~3000N, the cooling temperature is 1~40°C lower than the solidification point of the water-soluble medium, the cooling time is 10~600s, and the amount of the water-soluble medium is controlled to be 0.1~20mL, and the thickness after cooling and solidification is 20~200μm.

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 fixture is controlled to be 0.01-5.00 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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