Wafer cleaning method and wafer cleaning device

Abstract

The invention relates to a wafer cleaning method and a wafer cleaning device. The wafer cleaning method comprises the following steps: performing a megasonic cleaning process on a wafer subjected to CMP process treatment, wherein the megasonic power of the megasonic cleaning process is 300W-700W; performing a first cleaning process on the wafer to remove residual polishing solution particles and metal by-product particles after the CMP process, wherein an acidic cleaning solution with the pH value of 3-5 is adopted in the first cleaning process; performing a second cleaning process on the wafer to remove residual acidic cleaning liquid and metal ions, wherein alkaline cleaning liquid is adopted in the second cleaning process; and carrying out a drying treatment process on the wafer to remove residual particles, washing the wafer by using deionized water in the drying treatment process, carrying out auxiliary washing and spraying by using isopropanol and / or nitrogen, and spin-drying the wafer. According to the wafer cleaning method provided by the invention, particle residues on the surface of the wafer can be effectively removed, the cleaning efficiency and the cleaning effect are improved, the damage to the surface of the wafer is reduced, and the roughness of the surface of the wafer is reduced.

Description

Technical Field

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

[0002] In the semiconductor manufacturing production process, the grinding unit of the CMP (Chemical Mechanical Polishing) equipment mainly uses the combined action of grinding fluid and mechanical force to remove excess material from the wafer surface. The chemical components in the grinding fluid react with the wafer surface material to form easily removable substances. At the same time, the friction between the polishing pad and the wafer is used to physically remove the surface material to achieve surface flatness. For wafers with higher hardness, such as silicon carbide (SiC) substrate wafers, due to their ultra-high hardness, the polishing rate is low, and it is often necessary to use polishing fluid with oxidant components, greater downward pressure, higher polishing disc (polishing pad) speed, and longer operation time, which usually results in more residues (such as polishing fluid particles, metal byproduct particles, etc.) on the wafer surface and affects the quality of subsequent processes. Therefore, semiconductor wafers after the CMP process need to be cleaned.

[0003] At present, the commonly used post-CMP cleaning methods include immersion, spraying, brushing, ultrasonic, megasonic, and double-sided cleaning. Each cleaning method has its own advantages and disadvantages. For example, the traditional cleaning method often adopts tank immersion cleaning. Multiple cleaning objects can be accommodated in the cleaning box at the same time. Although it can shorten the cleaning time, the reuse of the cleaning liquid will cause mutual influence during the cleaning process of different batches of wafers, reducing the cleaning effect. Spray cleaning can quickly cover the surface of the wafer and is suitable for removing loose particles on the surface, but the high-pressure water pressure is difficult to accurately control and may cause damage to certain sensitive areas on the surface of the wafer. Ultrasonic megasonic cleaning is suitable for the removal of finer particles but has high operating requirements. Double-sided cleaning improves efficiency but increases equipment costs. Each CMP cleaning technology has its own unique application scenarios and limitations. Due to the limitations of different cleaning methods, the cleaning effect of silicon carbide wafers after the CMP process is poor, and the existing cleaning methods cannot effectively remove the residues on the surface of silicon carbide wafers after the CMP process.

[0004] Therefore, a process method is needed to combine the characteristics and advantages of different cleaning methods to effectively remove polishing liquid particles, metal byproduct particles and other residues on the surface of the silicon carbide wafer after the CMP process. Summary of the invention

[0005] Therefore, the present invention provides a wafer cleaning method to solve the problem in the prior art that due to the limitations of different cleaning methods themselves, the cleaning effect of the silicon carbide wafer after the CMP process is poor and the polishing liquid particles, metal by-product particles and other residues on the surface of the silicon carbide wafer after the CMP process cannot be effectively removed.

[0006] The present invention provides a wafer cleaning method, wherein the wafer is a wafer processed by a CMP process, comprising:

[0007] Perform megasonic cleaning on the wafer, the megasonic power of the megasonic cleaning process is 300W to 700W;

[0008] Performing a first cleaning process on the wafer to remove the polishing liquid particles and metal byproduct particles remaining after the CMP process, the first cleaning process uses an acidic cleaning solution, and the pH of the acidic cleaning solution is 3-5;

[0009] Performing a second cleaning process on the wafer to remove residual acid cleaning solution and metal ions, the second cleaning process uses an alkaline cleaning solution;

[0010] The wafer is subjected to a drying process to remove residual particles. The drying process uses deionized water to rinse the wafer, while isopropyl alcohol and / or nitrogen are used for auxiliary rinsing and spraying, and the wafer is spun dry.

[0011] Optionally, the acid cleaning solution is citric acid, oxalic acid or acetic acid;

[0012] The concentration of the acid cleaning solution is 1% to 10%.

[0013] Optionally, the alkaline cleaning solution is aqueous ammonia;

[0014] The concentration of the alkaline cleaning solution is 1% to 10%.

[0015] Optionally, the first cleaning process and / or the second cleaning process includes:

[0016] A rotating roller brush is used to scrub both sides of the wafer; the rotation speed of the roller brush is 150rpm to 300rpm, and there are bumps on the surface of the roller brush.

[0017] Optionally, in the first cleaning process and / or the second cleaning process, the rotation speed of the wafer is 30 rpm to 100 rpm;

[0018] The flow rate of the acid cleaning solution and / or the flow rate of the alkaline cleaning solution is 500 ml / min to 1500 ml / min.

[0019] Optionally, the first cleaning process and / or the second cleaning process further includes: under the action of a mechanical vibration device, the acid cleaning solution and / or the alkaline cleaning solution vibrates on the surface of the wafer.

[0020] Optionally, in the drying process, the rotation speed of the wafer is 1500 rpm to 2300 rpm, and the flow rate of isopropanol or the flow rate of nitrogen is 1500 ml / min to 2000 ml / min.

[0021] Optionally, the Mohs hardness of the wafer is 8 to 10;

[0022] The wafer is placed horizontally or vertically.

[0023] Optionally, the wafer is silicon carbide;

[0024] The polishing liquid in the CMP process is Ceria, SiO2 or Al2O3.

[0025] The present invention also provides a wafer cleaning device, comprising:

[0026] Megasonic cleaning unit, used for performing megasonic cleaning process on wafers after CMP process, the megasonic power of megasonic cleaning process is 300W~700W;

[0027] The first cleaning unit is used to perform a first cleaning process on the wafer to remove the polishing liquid particles and metal byproduct particles remaining after the CMP process. The first cleaning process uses an acidic cleaning liquid, and the pH of the acidic cleaning liquid is 3 to 5;

[0028] A second cleaning unit is used to perform a second cleaning process on the wafer to remove residual acid cleaning solution and metal ions, and the second cleaning process uses an alkaline cleaning solution;

[0029] The wafer spin-drying unit is used to perform a drying process on the wafer to remove residual particles. The drying process uses deionized water to rinse the wafer, and uses isopropyl alcohol and / or nitrogen for auxiliary rinsing and spraying, and spin-drying the wafer.

[0030] The technical solution of the present invention has the following advantages:

[0031] (1) The wafer cleaning method provided by the present invention has the following characteristics: first, the megasonic power of the megasonic cleaning process is 300W to 700W, which can effectively remove fine particles attached to the wafer surface; second, in the first cleaning process, the use of a weak acid cleaning solution with a pH of 3 to 5 can improve the removal efficiency of the polishing liquid particles and metal byproduct particles remaining on the wafer surface after the CMP process, thereby avoiding problems such as wafer damage and increased roughness caused by excessive corrosion of the wafer; in the second cleaning process, the use of an alkaline cleaning solution can effectively neutralize and remove the residual acidic cleaning solution, and can also adsorb and remove some residual metal ions; finally, in the drying process, isopropyl alcohol and / or nitrogen are used for auxiliary rinsing and spraying, and the different surface tensions between isopropyl alcohol and water can be used to achieve rapid replacement of the water film on the wafer surface with isopropyl alcohol, and auxiliary nitrogen spraying can effectively increase the spin-drying rate. Therefore, the wafer cleaning method provided by the present invention adopts different cleaning technologies to specifically remove different types of particle residues on the wafer surface after the CMP process, which can improve the cleaning efficiency and cleaning effect, reduce damage to the wafer surface, and reduce the roughness of the wafer surface.

[0032] (2) The wafer cleaning method provided by the present invention adopts mild cleaning agents such as citric acid, oxalic acid, acetic acid, etc. in the first cleaning process, and the concentration is 1% to 10%. The concentration is lower and the corrosiveness is weaker than that of the strong acid cleaning agents in the prior art. On the basis of ensuring the removal efficiency of the polishing liquid particles and the metal by-product particles, the damage to the wafer surface can be reduced and the roughness of the wafer surface can be reduced.

[0033] (3) The wafer cleaning method provided by the present invention adopts a mild cleaning agent such as ammonia water in the second cleaning process with a concentration of 1% to 10%, which is lower in concentration and less corrosive than the strong alkaline cleaning agent in the prior art. It can reduce damage to the wafer surface and reduce the roughness of the wafer surface while ensuring the effective removal of residual acidic cleaning solution and metal ions.

[0034] (4) In the wafer cleaning method provided by the present invention, a rotating roller brush is used to brush both sides of the wafer in the first cleaning process and / or the second cleaning process; the rotation speed of the roller brush is 150rpm~300rpm, and there are bumps on the surface of the roller brush. While the cleaning liquid and the residue chemically interact, physical brushing is used to remove the particle residue on the wafer surface, thereby improving the cleaning efficiency and cleaning effect.

[0035] (5) In the wafer cleaning method provided by the present invention, in the first cleaning process and / or the second cleaning process, the rotation speed of the wafer is 30rpm~100rpm; the flow rate of the acid cleaning solution and / or the flow rate of the alkaline cleaning solution is 500ml / min~1500ml / min, which can improve the wafer cleaning efficiency and cleaning quality and effectively remove particulate residues on the wafer surface.

[0036] (6) The wafer cleaning method provided by the present invention, in the first cleaning process and / or the second cleaning process, under the action of the mechanical vibration device, the acidic cleaning liquid and / or the alkaline cleaning liquid is combined with vibration technology while spraying the cleaning liquid, so as to vibrate on the surface of the wafer, which helps to loosen and remove particles adhering to the surface of the wafer, and helps the cleaning liquid to better penetrate between the particles or into the fine cracks on the surface of the wafer. At the same time, the mechanical vibration device also makes the sprayed cleaning liquid vibrate, so that small bubbles are generated when it contacts the wafer to achieve a more effective cleaning effect.

[0037] (7) In the wafer cleaning method provided by the present invention, in the drying process, the rotation speed of the wafer is 1500rpm~2300rpm, the flow rate of isopropyl alcohol or the flow rate of nitrogen is 1500ml / min~2000ml / min, and the different surface tensions between isopropyl alcohol and water can be utilized to achieve rapid replacement of the water film on the wafer surface by isopropyl alcohol, thereby improving the wafer drying efficiency. Auxiliary nitrogen spraying can effectively increase the spin-drying rate.

[0038] (8) The wafer cleaning device provided by the present invention can perform a megasonic cleaning process on the wafer after the CMP process through the megasonic cleaning unit. The megasonic power of the megasonic cleaning process is 300W to 700W, which can effectively remove fine particles attached to the wafer surface; the first cleaning unit can use a weak acid cleaning solution with a pH of 3 to 5 to perform a first cleaning process on the wafer, which can improve the removal efficiency of the polishing liquid particles and metal by-product particles remaining on the wafer surface after the CMP process, and avoid problems such as wafer damage and increased roughness caused by excessive corrosion of the wafer; the second cleaning unit can use an alkaline cleaning solution to perform a second cleaning process on the wafer, which can effectively neutralize and remove the residual acidic cleaning solution, and can also adsorb and remove some residual metal ions; the wafer spin-drying unit can perform a drying process on the wafer to remove residual particles, and isopropyl alcohol and / or nitrogen can be used for auxiliary rinsing and spraying. The different surface tensions between isopropyl alcohol and water can be used to achieve rapid replacement of the water film on the wafer surface with isopropyl alcohol, and auxiliary nitrogen spraying can effectively increase the spin-drying rate. Therefore, the wafer cleaning device provided by the present invention can specifically remove different types of particle residues on the wafer surface after the CMP process by adopting cleaning units with different cleaning methods, thereby improving the cleaning efficiency and cleaning effect, reducing damage to the wafer surface, and reducing the roughness of the wafer surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 A schematic diagram of a process of a wafer cleaning method according to an embodiment of the present invention;

[0041] Figure 2 A schematic diagram of wafer cleaning in a first cleaning process and / or a second cleaning process according to an embodiment of the present invention;

[0042] Figure 3 A schematic diagram of a wafer being placed vertically in a first cleaning process and / or a second cleaning process according to an embodiment of the present invention;

[0043] Figure 4 A schematic diagram of horizontal placement of wafers in a first cleaning process and / or a second cleaning process according to an embodiment of the present invention;

[0044] Figure 5 A schematic diagram of a specific process of a wafer cleaning method according to an embodiment of the present invention;

[0045] Figure 6 A schematic structural diagram of a wafer cleaning device according to an embodiment of the present invention;

[0046] Figure 7 The figure is a schematic structural diagram of another wafer cleaning device according to an embodiment of the present invention.

[0047] Description of reference numerals:

[0048] 100-megasonic cleaning unit; 200-first cleaning unit; 300-second cleaning unit; 400-wafer drying unit; 500-third cleaning unit; 600-wafer; 11-rolling brush; 12-rotating wheel; 13-spraying device. DETAILED DESCRIPTION

[0049] Due to the high hardness of silicon carbide materials, silicon carbide substrate wafers use different grinding fluids during the polishing process. The grinding fluid not only contains micro-abrasive particles to mechanically wear the surface, but also its components can chemically react with the surface material to improve its grinding efficiency. However, some by-products and polishing fluid and polishing pad residues will inevitably be produced during the polishing process, so the post-polishing cleaning step is crucial. From a process perspective, the present invention proposes a single-wafer cleaning method that combines multiple cleaning methods, and uses cleaning fluids of different components to achieve an efficient and clean cleaning effect.

[0050] In order to meet the needs of post-CMP cleaning, the industry has developed a variety of cleaning technologies to improve cleaning efficiency and cleaning quality, but each CMP cleaning technology has its own unique application scenarios and limitations. ① Ultrasonic cleaning: Using the cavitation effect generated by ultrasound to generate shock waves when tiny bubbles burst, it helps remove surface attachments; but the disadvantage of ultrasonic cleaning is that it has high operating requirements; ② Megasonic cleaning: A more advanced form than ultrasound, with a higher frequency, it can remove surface contaminants more finely, and megasonic cleaning has higher operating requirements. ③ Brush cleaning: Directly contact the wafer surface with a rotating brush or brush pad to physically remove residues, but the cleaning effect is general and cannot remove attached chemicals. ④ Spray cleaning: Use high-pressure spray to remove surface particles, and at the same time use chemical cleaning fluid to improve the cleaning effect; spray cleaning can quickly cover the wafer surface and is suitable for removing loose particles on the surface, but the high-pressure water pressure is difficult to accurately control and may cause damage to certain sensitive areas on the wafer surface. ⑤ Immersion cleaning: Immerse the wafer in the cleaning solution to remove contaminants by immersion and circulation, but fine particles cannot be removed. ⑥ Double-sided cleaning: For some special needs, both sides of the wafer can be cleaned at the same time to improve cleaning efficiency, but this will increase equipment costs.

[0051] In order to solve the problem in the prior art that, due to the limitations of different cleaning methods themselves, the cleaning effect of silicon carbide wafers after CMP process is poor, and the polishing liquid particles, metal by-product particles and other residues on the surface of the silicon carbide wafer after CMP process cannot be effectively removed, the present invention provides a wafer cleaning method, the wafer is a wafer after CMP process, and the method comprises the following steps: performing a megasonic cleaning process on the wafer, the megasonic power of the megasonic cleaning process is 300W-700W; performing a first cleaning process on the wafer to remove the polishing liquid particles and metal by-product particles remaining after the CMP process, the first cleaning process adopts an acidic cleaning liquid, and the pH of the acidic cleaning liquid is 3-5; performing a second cleaning process on the wafer to remove the residual acidic cleaning liquid and metal ions, the second cleaning process adopts an alkaline cleaning liquid; performing a drying process on the wafer to remove the residual particles, the drying process uses deionized water to rinse the wafer, and simultaneously uses isopropyl alcohol and / or nitrogen for auxiliary rinsing and spraying, and spin-drying the wafer.

[0052] The present invention also provides a wafer cleaning device, comprising: a megasonic cleaning unit, which is used to perform a megasonic cleaning process on a wafer after a CMP process, and the megasonic power of the megasonic cleaning process is 300W-700W; a first cleaning unit, which performs a first cleaning process on the wafer to remove polishing liquid particles and metal byproduct particles remaining after the CMP process, and the first cleaning process uses an acidic cleaning liquid, and the pH of the acidic cleaning liquid is 3-5; a second cleaning unit, which performs a second cleaning process on the wafer to remove residual acidic cleaning liquid and metal ions, and the second cleaning process uses an alkaline cleaning liquid; a wafer spin-drying unit, which performs a drying process on the wafer to remove residual particles, and the drying process uses deionized water to rinse the wafer, and simultaneously uses isopropyl alcohol and / or nitrogen for auxiliary rinsing and spraying, and spin-dries the wafer.

[0053] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. In the description of the present invention, it should be noted that the terms "first", "second" and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0054] Example 1

[0055] refer to Figure 1 This embodiment provides a wafer cleaning method, wherein the wafer is a wafer that has been processed by a CMP process, and the wafer cleaning method includes:

[0056] S101, performing a megasonic cleaning process on the wafer, wherein the megasonic cleaning power of the megasonic cleaning process is 300W to 700W;

[0057] S102, performing a first cleaning process on the wafer to remove polishing liquid particles and metal byproduct particles remaining after the CMP process, the first cleaning process uses an acidic cleaning solution, and the pH of the acidic cleaning solution is 3-5;

[0058] S103, performing a second cleaning process on the wafer to remove residual acid cleaning solution and metal ions, the second cleaning process uses an alkaline cleaning solution;

[0059] S104, performing a drying process on the wafer to remove residual particles. The drying process uses deionized water to rinse the wafer, and uses isopropyl alcohol and / or nitrogen for auxiliary rinsing and spraying, and then spin-dries the wafer.

[0060] In specific implementation, the cleaning agents in the existing cleaning technology usually use strong acids, strong alkalis, strong oxidants or organic solvents, which are not only toxic and pollute the environment, but also have strong corrosiveness, and are prone to cause excessive loss of substrates after cleaning and increased surface roughness. In this embodiment, the first cleaning process uses an acidic cleaning solution with a pH of 3 to 5, and the second cleaning process uses an alkaline cleaning solution with a pH of 10 to 12, which can ensure the cleaning efficiency while avoiding problems such as wafer damage and increased roughness caused by excessive corrosion of the wafer. In addition, the material of the wafer in this embodiment can be single crystal silicon, lithium niobate, lithium tantalate, gallium nitride, gallium arsenide, etc.

[0061] The wafer cleaning method provided in this embodiment has the following characteristics: first, the megasonic power of the megasonic cleaning process is 300W to 700W, which can effectively remove fine particles attached to the wafer surface; second, in the first cleaning process, the use of a weak acid cleaning solution with a pH of 3 to 5 can improve the removal efficiency of the polishing liquid particles and metal by-product particles remaining on the wafer surface after the CMP process, thereby avoiding problems such as wafer damage and increased roughness caused by excessive corrosion of the wafer; in the second cleaning process, the use of an alkaline cleaning solution can effectively neutralize and remove the residual acidic cleaning solution, and can also adsorb and remove some residual metal ions; finally, in the drying process, isopropyl alcohol and / or nitrogen are used for auxiliary rinsing and spraying, and the different surface tension characteristics of isopropyl alcohol and water can be used to achieve rapid replacement of the water film on the wafer surface with isopropyl alcohol, and auxiliary nitrogen spraying can effectively increase the spin-drying rate. Therefore, the wafer cleaning method provided in this embodiment uses different cleaning technologies to specifically remove different types of particle residues on the wafer surface after the CMP process, which can improve the cleaning efficiency and cleaning effect, reduce damage to the wafer surface, and reduce the roughness of the wafer surface.

[0062] Further, in some embodiments, the acidic cleaning solution is citric acid, oxalic acid or acetic acid;

[0063] The concentration of the acid cleaning solution is 1% to 10%.

[0064] The wafer cleaning method provided in this embodiment uses mild cleaning agents such as citric acid, oxalic acid, acetic acid, etc. in the first cleaning process with a concentration of 1% to 10%, which is lower in concentration and less corrosive than the strong acid cleaning agents in the prior art. It can reduce damage to the wafer surface and reduce the roughness of the wafer surface while ensuring the removal efficiency of polishing liquid particles and metal by-product particles.

[0065] Further, in some embodiments, the alkaline cleaning solution is ammonia water;

[0066] The concentration of the alkaline cleaning solution is 1% to 10%.

[0067] The wafer cleaning method provided in this embodiment adopts a mild cleaning agent such as ammonia water in the second cleaning process and the concentration is 1% to 10%, which is lower in concentration and less corrosive than the strong alkaline cleaning agent in the prior art. It can reduce damage to the wafer surface and reduce the roughness of the wafer surface while ensuring the effective removal of residual acidic cleaning solution and metal ions.

[0068] Further, in some embodiments, the first cleaning process and / or the second cleaning process includes:

[0069] A rotating roller brush is used to scrub both sides of the wafer; the rotation speed of the roller brush is 150rpm to 300rpm, and there are bumps on the surface of the roller brush.

[0070] The wafer cleaning method provided by the present invention uses a rotating roller brush to brush both sides of the wafer in the first cleaning process and / or the second cleaning process; the rotation speed of the roller brush is 150rpm~300rpm, and there are bumps on the surface of the roller brush. While the cleaning liquid and the residue chemically interact, physical brushing is used to remove the particle residue on the wafer surface, thereby improving the cleaning efficiency and cleaning effect.

[0071] Further, in some embodiments, in the first cleaning process and / or the second cleaning process, the rotation speed of the wafer is 30 rpm to 100 rpm, for example, 30 rpm, 50 rpm, 70 rpm, or 100 rpm;

[0072] The flow rate of the acid cleaning solution and / or the flow rate of the alkaline cleaning solution is 500 ml / min to 1500 ml / min, for example, 500 ml / min, 800 ml / min, 1000 ml / min, 1300 ml / min or 1500 ml / min.

[0073] When implementing it, Figure 2 As shown, in the first cleaning process and / or the second cleaning process, the wafer 600 and the roller brush 11 rotate simultaneously to achieve a higher cleaning effect; the flow rate of the acidic cleaning liquid and / or the alkaline cleaning liquid is sprayed to the contact pads of the two sides of the wafer 600 and the roller brush 11 through the spray device 13, so that the cleaning liquid can be evenly distributed on both sides of the wafer 600 to achieve a more uniform cleaning effect; the flow rate of the acidic cleaning liquid and / or the flow rate of the alkaline cleaning liquid is 500ml / min~1500ml / min, which can make the cleaning liquid react better with the residue on the surface of the wafer 600, thereby improving the cleaning efficiency and cleaning effect.

[0074] In the wafer cleaning method provided in this embodiment, in the first cleaning process and / or the second cleaning process, the rotation speed of the wafer is 30rpm~100rpm; the flow rate of the acidic cleaning solution and / or the flow rate of the alkaline cleaning solution is 500ml / min~1500ml / min, and the roller brush and the wafer rotate simultaneously to achieve a higher cleaning effect, improve the wafer cleaning efficiency and cleaning quality, and effectively remove particulate residues on the wafer surface.

[0075] Furthermore, in some embodiments, the first cleaning process and / or the second cleaning process further includes: under the action of a mechanical vibration device, the acid cleaning solution and / or the alkaline cleaning solution vibrates on the surface of the wafer.

[0076] The wafer cleaning method provided in this embodiment, in the first cleaning process and / or the second cleaning process, under the action of the mechanical vibration device, the acidic cleaning liquid and / or the alkaline cleaning liquid is combined with vibration technology while spraying the cleaning liquid, so as to vibrate on the surface of the wafer, which helps to loosen and remove particles adhering to the surface of the wafer, and helps the cleaning liquid to better penetrate into the fine cracks between the particles or on the surface of the wafer. At the same time, the mechanical vibration device also makes the sprayed cleaning liquid vibrate, so that small bubbles are generated when it contacts the wafer to achieve a more effective cleaning effect.

[0077] Furthermore, in some embodiments, during the drying process, the rotation speed of the wafer is 1500 rpm to 2300 rpm, and the flow rate of isopropanol or the flow rate of nitrogen is 1500 ml / min to 2000 ml / min.

[0078] In the wafer cleaning method provided in this embodiment, in the drying process, the rotation speed of the wafer is 1500rpm~2300rpm, the flow rate of isopropyl alcohol or the flow rate of nitrogen is 1500ml / min~2000ml / min, and the different surface tensions between isopropyl alcohol and water can be used to achieve rapid replacement of the water film on the wafer surface by isopropyl alcohol, thereby improving the wafer drying efficiency, and the auxiliary nitrogen spray can effectively increase the spin-drying rate.

[0079] Further, in some embodiments, the Mohs hardness of the wafer is 8 to 10;

[0080] The wafer is placed horizontally or vertically.

[0081] During specific implementation, the wafer can be placed horizontally or vertically in different cleaning processes according to process conditions.

[0082] In one example, if Figure 3As shown, the wafer 600 is placed vertically in the first cleaning process and / or the second cleaning process. The vertical placement is conducive to the flow of the cleaning liquid, and the roller brush 11 is located on the left and right sides of the wafer to rotate (the speed can be controlled at 150rpm to 300rpm), and the wafer 600 rotates (the speed can be controlled at 30rpm to 100rpm) to achieve a better cleaning effect.

[0083] In another example, Figure 4 As shown, the wafer 600 is placed horizontally in the first cleaning process and / or the second cleaning process. The horizontal placement is conducive to the stable fixation of the wafer 600, and the roller brush 11 is located on the upper and lower sides of the wafer 600 to rotate, and the wafer 600 also rotates at the same time.

[0084] In addition, horizontal or vertical wafer placement can be selected as required in the megasonic cleaning process and drying process.

[0085] Further, in some embodiments, the wafer is silicon carbide;

[0086] The polishing liquid in the CMP process is Ceria, SiO2 or Al2O3.

[0087] Furthermore, in some embodiments, the wafer cleaning method further comprises, after the second cleaning process:

[0088] The wafer is subjected to a third cleaning process to remove residues on the surface of the wafer, and the third cleaning process uses an alkaline cleaning solution or an acidic cleaning solution.

[0089] In specific implementation, the third cleaning process can select an acidic cleaning solution or an alkaline cleaning solution according to conditions such as the material of the wafer and the polishing solution used in the CMP process.

[0090] In a specific example, a specific flow chart of a wafer cleaning method is as follows: Figure 5 shown.

[0091] S201, performing a megasonic cleaning process on the silicon carbide wafer after the CMP process, wherein the megasonic cleaning process has a megasonic power of 300W to 700W;

[0092] S202, performing the first cleaning process on the silicon carbide wafer to remove the polishing liquid particles and metal by-product particles remaining after the CMP process, using citric acid, oxalic acid or acetic acid with a pH of 3 to 5 and a concentration of 1% to 10% as the cleaning liquid, and at the same time under the action of a mechanical vibration device, the cleaning liquid vibrates on the surface of the wafer; the flow rate of the cleaning liquid is 500ml / min to 1500ml / min; the rotation speed of the silicon carbide wafer is 30rpm to 100rpm, the rotation speed of the roller brush is 150rpm to 300rpm, and there are bumps on the surface of the roller brush.

[0093] S203, a second cleaning process is performed on the silicon carbide wafer to remove residual acidic cleaning solution and metal ions, and ammonia water with a concentration of 1% to 10% is used as the cleaning solution. At the same time, under the action of a mechanical vibration device, the cleaning solution vibrates on the surface of the wafer; the flow rate of the cleaning solution is 500ml / min to 1500ml / min; the rotation speed of the silicon carbide wafer is 30rpm to 100rpm, the rotation speed of the roller brush is 150rpm to 300rpm, and there are bumps on the surface of the roller brush.

[0094] S204, performing a drying process on the silicon carbide wafer to remove residual particles, the drying process uses deionized water to rinse the silicon carbide wafer, and uses isopropyl alcohol and / or nitrogen for auxiliary rinsing and spraying, and then spin-dries the silicon carbide wafer; the rotation speed of the silicon carbide wafer is 1500rpm~2300rpm, and the flow rate of isopropyl alcohol or nitrogen is 1500ml / min~2000ml / min.

[0095] After testing, the above-mentioned wafer cleaning method has a cleaning effect of 50 to 500 silicon carbide wafers, which is significantly improved compared to the existing wet chemical cleaning method (RCA standard cleaning method) with a cleaning effect of more than 1,000 wafers. The wafer cleaning method provided in this embodiment has the same cleaning effect for polishing solutions with different components such as Ceria / SiO2 / Al2O3.

[0096] Example 2

[0097] refer to Figure 6 The present invention also provides a wafer cleaning device, comprising:

[0098] The megasonic cleaning unit 100 is used to perform a megasonic cleaning process on the wafer after the CMP process, and the megasonic power of the megasonic cleaning process is 300W to 700W;

[0099] The first cleaning unit 200 is used to perform a first cleaning process on the wafer to remove the polishing liquid particles and metal byproduct particles remaining after the CMP process. The first cleaning process uses an acidic cleaning liquid, and the pH of the acidic cleaning liquid is 3 to 5;

[0100] The second cleaning unit 300 is used to perform a second cleaning process on the wafer to remove residual acid cleaning solution and metal ions, and the second cleaning process uses an alkaline cleaning solution;

[0101] The wafer spin-drying unit 400 is used to perform a drying process on the wafer to remove residual particles. The drying process uses deionized water to rinse the wafer, and uses isopropyl alcohol and / or nitrogen for auxiliary rinsing and spraying, and spin-dries the wafer.

[0102] In a specific implementation, the megasonic cleaning unit may be a megasonic cleaning device (Mega), the wafer drying unit 400 may be a spin rinse dryer (SRD), and the first cleaning unit 200 and the second cleaning unit 300 may be roller brush cleaning devices. The wafer cleaning device provided in this embodiment integrates a megasonic cleaning device, a spin rinse dryer, and a roller brush cleaning device, and selects cleaning fluids of different action categories to meet the cleaning requirements of different wafers and achieve different process indicators.

[0103] The wafer cleaning device provided in this embodiment can perform a megasonic cleaning process on the wafer after the CMP process through the megasonic cleaning unit. The megasonic power of the megasonic cleaning process is 300W to 700W, which can effectively remove fine particles attached to the wafer surface; the first cleaning unit can use a weak acid cleaning solution with a pH of 3 to 5 to perform a first cleaning process on the wafer, which can improve the removal efficiency of the polishing liquid particles and metal by-product particles remaining on the wafer surface after the CMP process, and avoid problems such as wafer damage and increased roughness caused by excessive corrosion of the wafer; the second cleaning unit can use an alkaline cleaning solution to perform a second cleaning process on the wafer, which can effectively neutralize and remove the residual acidic cleaning solution, and can also adsorb and remove some residual metal ions; the wafer spin-drying unit can perform a drying process on the wafer to remove residual particles, and isopropyl alcohol and / or nitrogen can be used for auxiliary rinsing and spraying. The different surface tension characteristics of isopropyl alcohol and water can be used to achieve rapid replacement of the water film on the wafer surface by isopropyl alcohol, and auxiliary nitrogen spraying can effectively increase the spin-drying rate. Therefore, the wafer cleaning device provided in this embodiment can specifically remove different types of particle residues on the wafer surface after the CMP process by adopting cleaning units with different cleaning methods, thereby improving the cleaning efficiency and cleaning effect, reducing damage to the wafer surface, and reducing the roughness of the wafer surface.

[0104] Furthermore, in some embodiments, Figure 2 As shown, a rotating roller brush 11 and a spray device 13 are provided in the first cleaning unit 200 and / or the second cleaning unit 300; the roller brush 11 is used to brush the wafer surface, and the spray device 13 is used to spray the cleaning liquid; the rotation speed of the roller brush 11 is 150rpm~300rpm, and there are bumps on the surface of the roller brush 11.

[0105] In specific implementation, two roller brushes made of PVA sponge are fixed on both sides of the wafer. The surface of the roller brush contains a series of bumps that make cleaning easier and more thorough. Due to its special structure, SiC wafers need to be cleaned on both sides. This cleaning structure can brush both sides of the wafer at the same time, improving the cleaning efficiency of SiC wafers. The continuous contact between the roller brush and the workpiece surface is a tribological process between boundary and elastic fluid lubrication. The contact force between the roller brush and the wafer is combined with the drag force of the fluid force to remove particles that penetrate into the wafer during the polishing process. At the same time, the roller brush has a hollow structure and deionized water is passed through the hollow tube to keep the sponge brush moist and soft at all times, thereby extending the service life of the roller brush.

[0106] Furthermore, in some embodiments, Figure 2 As shown, four or six rotating wheels 12 are provided in the first cleaning unit 200 and / or the second cleaning unit 300 , and the rotating wheels 12 are used to limit the position of the wafer 600 .

[0107] In a specific implementation, in one embodiment, Figure 2 As shown, in the first cleaning unit and / or the second cleaning unit, four rotating wheels 12 are provided for limiting the wafer 600, and four spray devices 13 are also provided. Two spray devices 13 are provided on both sides of the wafer respectively, and the spraying position of the spray device 13 is located at the contact point between the wafer 600 and the roller brush 11, so that the cleaning liquid is evenly distributed on both sides of the wafer to achieve a more uniform cleaning effect.

[0108] Furthermore, in some embodiments, the first cleaning unit 200 and / or the second cleaning unit 300 further includes: a mechanical vibration device for causing the acidic cleaning solution and / or the alkaline cleaning solution to vibrate on the surface of the wafer.

[0109] The wafer cleaning device provided in this embodiment is provided with a mechanical vibration device in the first cleaning unit and / or the second cleaning unit, which can make the acidic cleaning liquid and / or the alkaline cleaning liquid vibrate on the wafer surface, thereby helping to loosen and remove particles adhered to the wafer surface and helping the cleaning liquid to better penetrate into the fine cracks between the particles or on the wafer surface.

[0110] Further, in some embodiments, the Mohs hardness of the wafer is 8 to 10;

[0111] The wafer is placed horizontally or vertically.

[0112] During specific implementation, the wafers can be placed horizontally or vertically in different cleaning units according to requirements.

[0113] In one example, if Figure 3As shown, the wafer 600 is placed vertically in the first cleaning unit 200 and / or the second cleaning unit 300. The vertical placement is conducive to the flow of the cleaning liquid, and the roller brush 11 is located on the left and right sides of the wafer to rotate (the speed can be controlled at 150rpm to 300rpm), and the wafer 600 rotates (the speed can be controlled at 30rpm to 100rpm) to achieve a better cleaning effect.

[0114] In another example, Figure 4 As shown, the wafer 600 is placed horizontally in the first cleaning unit 200 and / or the second cleaning unit 300. The horizontal placement is conducive to the stable fixation of the wafer 600, and the roller brush 11 is located on the upper and lower sides of the wafer 600 to rotate, and the wafer 600 also rotates at the same time.

[0115] In addition, the megasonic cleaning unit 100 and the wafer drying unit 400 can also be designed with a horizontal or vertical wafer placement as required.

[0116] Furthermore, in some embodiments, Figure 7 As shown, the wafer cleaning device also includes:

[0117] A third cleaning unit 500 performs a third cleaning process on the wafer to remove residues on the surface of the wafer, and the third cleaning process uses an alkaline cleaning solution or an acidic cleaning solution;

[0118] In specific implementation, the third cleaning process can select an acidic cleaning solution or an alkaline cleaning solution according to conditions such as the material of the wafer and the polishing solution used in the CMP process.

[0119] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A wafer cleaning method, wherein the wafer is a wafer processed by a CMP process, characterized in that: include: Performing a megasonic cleaning process on the wafer, wherein the megasonic cleaning process has a megasonic power of 300W to 700W; Performing a first cleaning process on the wafer to remove polishing liquid particles and metal byproduct particles remaining after the CMP process, wherein the first cleaning process uses an acidic cleaning solution, and the pH of the acidic cleaning solution is 3 to 5; Performing a second cleaning process on the wafer to remove the residual acidic cleaning solution and metal ions, wherein the second cleaning process uses an alkaline cleaning solution; The wafer is subjected to a drying process to remove residual particles. The drying process uses deionized water to rinse the wafer, and isopropyl alcohol and / or nitrogen gas are used for auxiliary rinsing and spraying, and the wafer is dried.

2. The wafer cleaning method according to claim 1, characterized in that: The acidic cleaning solution is citric acid, oxalic acid or acetic acid; The concentration of the acid cleaning solution is 1% to 10%.

3. The wafer cleaning method according to claim 1, characterized in that: The alkaline cleaning solution is ammonia water; The concentration of the alkaline cleaning solution is 1% to 10%.

4. The wafer cleaning method according to claim 2 or 3, characterized in that: The first cleaning process and / or the second cleaning process include: A rotating roller brush is used to brush both sides of the wafer; the rotation speed of the roller brush is 150 rpm to 300 rpm, and there are convex points on the surface of the roller brush.

5. The wafer cleaning method according to claim 4, characterized in that: In the first cleaning process and / or the second cleaning process, The rotation speed of the wafer is 30 rpm to 100 rpm; The flow rate of the acid cleaning solution and / or the flow rate of the alkaline cleaning solution is 500 ml / min to 1500 ml / min.

6. The wafer cleaning method according to claim 1, characterized in that: The first cleaning process and / or the second cleaning process further includes: under the action of a mechanical vibration device, the acid cleaning solution and / or the alkaline cleaning solution vibrates on the surface of the wafer.

7. The wafer cleaning method according to claim 1, characterized in that: In the drying process, the rotation speed of the wafer is 1500 rpm to 2300 rpm, and the flow rate of the isopropanol or the flow rate of the nitrogen is 1500 ml / min to 2000 ml / min.

8. The wafer cleaning method according to claim 1, characterized in that: The Mohs hardness of the wafer is 8 to 10; The wafer is placed horizontally or vertically.

9. The wafer cleaning method according to claim 8, characterized in that: The wafer is silicon carbide; The polishing liquid in the CMP process is Ceria, SiO2 or Al2O3.

10. A wafer cleaning device, characterized in that: include: A megasonic cleaning unit, used for performing a megasonic cleaning process on the wafer after the CMP process, wherein the megasonic cleaning process has a megasonic power of 300W to 700W; A first cleaning unit, used for performing a first cleaning process on the wafer to remove polishing liquid particles and metal byproduct particles remaining after the CMP process, wherein the first cleaning process uses an acidic cleaning liquid, and the pH of the acidic cleaning liquid is 3 to 5; A second cleaning unit, used for performing a second cleaning process on the wafer to remove the residual acid cleaning solution and metal ions, wherein the second cleaning process uses an alkaline cleaning solution; The wafer drying unit is used to perform a drying process on the wafer to remove residual particles. The drying process uses deionized water to rinse the wafer, and uses isopropyl alcohol and / or nitrogen for auxiliary rinsing and spraying, and then spin-dries the wafer.

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