Improved RCA cleaning process and cleaning equipment

Abstract

The invention relates to the technical field of RCA cleaning, provides an improved RCA cleaning process and cleaning equipment, and provides a process for carrying out RCA cleaning on a silicon wafer, by preparing a mixed acid solution, two originally needed pickling steps are reduced, the original cleaning effect can be achieved only through one-step pickling, the whole cleaning process is mostly under the room temperature condition, and the cleaning efficiency is greatly improved. The pickling step is reduced, meanwhile, the use of chemical agents is reduced, the cost is reduced, and the cleaning quality can be guaranteed. The liquid receiving plate is horizontally located at the bottom of the cleaning container all the time in the transferring process of the cleaning container and used for receiving falling waste liquid, the waste liquid is prevented from polluting the table top or the cleaning groove, meanwhile, the liquid receiving plate can be controlled by the mechanical arm, the position is adjusted to avoid interfering with the action of the workbench, and the liquid receiving plate can enter the cleaning groove to be automatically cleaned after receiving the waste liquid.

Description

Technical Field

[0001] The present invention relates to the technical field of RCA cleaning, and in particular to an improved RCA cleaning process and cleaning equipment. Background Art

[0002] RCA is a typical wet chemical cleaning method that is still the most commonly used one. This cleaning method mainly includes the following cleaning solutions.

[0003] (1) SPM: H2SO4 / H2O2120~150℃ SPM has a high oxidation capacity. It can oxidize metals and dissolve them in the cleaning solution. It can also oxidize organic matter to generate CO2 and H2O. Using SPM to clean silicon wafers can remove heavy organic contamination and some metals on the surface of silicon wafers. However, when the organic contamination is particularly serious, it will carbonize and be difficult to remove.

[0004] (2) HF (DHF): HF (DHF) 20~25℃ DHF can remove the natural oxide film on the surface of the silicon wafer. Therefore, the metal attached to the natural oxide film will be dissolved into the cleaning solution. At the same time, DHF inhibits the formation of the oxide film. Therefore, it is easy to remove metals such as Al, Fe, Zn, Ni on the surface of the silicon wafer. DHF can also remove metal hydroxides attached to the natural oxide film. When cleaning with DHF, when the natural oxide film is corroded, the silicon on the surface of the silicon wafer is almost not corroded.

[0005] (3) APM (SC-1): NH4OH / H2O2 / H2O 30~80℃ Due to the effect of H2O2, there is a natural oxide film (SiO2) on the surface of the silicon wafer, which is hydrophilic. The surface of the silicon wafer and the particles can be penetrated by the cleaning liquid. Since the natural oxide layer on the surface of the silicon wafer and the Si on the surface of the silicon wafer are corroded by NH4OH, the particles attached to the surface of the silicon wafer fall into the cleaning liquid, thereby achieving the purpose of removing the particles. While NH4OH corrodes the surface of the silicon wafer, H2O2 forms a new oxide film on the surface of the oxidized silicon wafer.

[0006] (4) HPM (SC-2): HCl / H2O2 / / H2O 65~85℃ Used to remove metal contaminants such as sodium, iron, and magnesium from the surface of silicon wafers. HPM can remove Fe and Zn at room temperature.

[0007] The general idea of ​​cleaning is to first remove organic contamination on the surface of the silicon wafer, because organic matter will cover part of the silicon wafer surface, making the oxide film and related contamination difficult to remove; then dissolve the oxide film, because the oxide layer is a "contamination trap" and will also introduce epitaxial defects; finally, remove particles, metals and other contaminants, and passivate the silicon wafer surface.

[0008] At present, with the continuous development of new cleaning processes, the main purpose is to reduce the process steps as much as possible under room temperature conditions, and minimize the use of ultra-clean water and chemical solutions to achieve good cleaning effects, so as to reduce costs, improve cleaning quality, facilitate the recovery and utilization of waste liquids, and reduce pollution to the environment. Summary of the invention The present invention provides an improved RCA cleaning process and cleaning equipment, which simplifies the conventional two acid cleaning steps into one by using a mixed acid solution while ensuring better cleaning quality, so as to reduce costs and improve cleaning efficiency.

[0009] To this end, the technical solutions adopted are as follows: An improved RCA cleaning process comprises the following steps: S1: Place the silicon wafer into a cleaning container and immerse the cleaning container in deionized water; S2: Take out the cleaning container, transfer it to the mixed acid solution, and soak it for 40s~60s at -10℃~-5℃; S3: taking the cleaning container out of the mixed acid solution and rinsing the silicon wafer with deionized water until all chemicals are rinsed away; S4: Transfer the cleaning container to an ultrasonic cleaner and clean it for 200s~300s at a cleaning frequency of 28KHZ~40KHZ; S5: Take out the cleaning container, take out the silicon wafer and put it into the dryer for drying until no moisture remains on the surface of the silicon wafer.

[0010] A further technical solution is that the mixed acid solution contains HNO3 with a concentration of 65% to 68%, HF with a concentration of 40% to 50%, CH3COOH with a concentration of 95% to 98% and H2SO4 with a concentration of 95% to 98%, and the volume ratio of the four is 3:1:1:3.

[0011] An improved RCA cleaning device comprises an equipment body, wherein the equipment body comprises a control system, a liquid preparation and supply system, a liquid drainage system and a working cabin, wherein a plurality of cleaning slots are provided on a working table of the working cabin, and the equipment is suitable for any one of the above-mentioned improved RCA cleaning processes; the equipment also comprises a cleaning container adapted to the cleaning slot for holding silicon wafers, wherein a lifting mechanism capable of transferring the cleaning container to different cleaning slots is fixed on the top of the working cabin, wherein the cleaning slots have four, namely, an immersion slot, a pickling slot, a rinsing slot and an ultrasonic slot, wherein a mechanical arm is fixed on the side wall of the working cabin, wherein a liquid receiving plate is fixed on the working end of the mechanical arm, and wherein the liquid receiving plate is always horizontally located at the bottom thereof during the transfer of the cleaning container.

[0012] A further technical solution is that the liquid receiving plate is in a circular arc structure that is concave downward when in a horizontal state.

[0013] A further technical solution is that a snap-in hole is provided on the outer edge of the liquid receiving plate, the working end of the robotic arm is a clamping structure, the clamping structure includes two clamping blocks with adjustable spacing, and snap-in blocks matching the snap-in holes are fixed on surfaces of the two clamping blocks close to each other, and the robotic arm is fixed to the liquid receiving plate by respectively inserting the two snap-in blocks into the two ends of the snap-in holes.

[0014] A further technical solution is that the cleaning container is a square cylindrical structure, a side wall of the cleaning container is provided with a plurality of strip positioning holes arranged in parallel, and the other three side walls are provided with a plurality of strip insertion holes corresponding to the strip positioning holes, and the three strip insertion holes corresponding to the same strip positioning hole are connected as a whole.

[0015] A further technical solution is that a hook is fixed to the hoisting position of the hoisting mechanism, and a hooking groove matching the hook is provided on the edge of the cleaning container.

[0016] A further technical solution is that the hook is a double-hook structure with an adjustable distance, and the double hooks respectively hook the two sides of the cleaning container.

[0017] The working principle and beneficial effects of this application are: 1. A process method is provided for RCA cleaning of silicon wafers. By configuring a mixed acid solution, the two pickling steps originally required are reduced, and only one pickling step is needed to achieve the original cleaning effect. The entire cleaning process is mostly at room temperature. While reducing the pickling steps, the use of chemical agents is reduced, reducing costs, and ensuring the cleaning quality.

[0018] 2. Through the liquid receiving plate, the cleaning container is always horizontally located at the bottom during the transfer process to receive the dropped waste liquid to prevent the waste liquid from contaminating the table or the cleaning tank. At the same time, the liquid receiving plate can also be controlled by the robotic arm to adjust its position and store it on the side wall of the working cabin to avoid interfering with other operations on the workbench. It can also be automatically cleaned in the deionized water in the cleaning tank after receiving the waste liquid.

[0019] 3. The cleaning container is used to hold silicon wafers. There is a certain gap between the strip positioning holes so as not to hinder the water flow from entering and flushing. The silicon wafer is inserted from the strip insertion hole and positioned using the strip positioning hole, regardless of the size of the silicon wafer. During cleaning, the placement direction of the cleaning container can be adjusted according to the actual situation so that the silicon wafer can be placed vertically or horizontally. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0021] Figure 1 This is a schematic diagram of the overall structure of the device body described in this application; Figure 2 It is a schematic cross-sectional structural diagram of the device body described in this application; Figure 3 This is a schematic diagram of the top view of the cleaning tank described in this application; Figure 4 This is a schematic diagram of the structure of the cleaning container described in this application; Figure 5 This is a schematic diagram of the structure of the robotic arm described in this application; Figure 6 This is a schematic structural diagram of the liquid receiving plate described in this application.

[0022] In the figure: 1. cleaning container; 11. strip positioning hole; 12. strip insertion hole; 13. hooking groove; 2. lifting mechanism; 21. lifting hook; 31. immersion tank; 32. pickling tank; 33. flushing tank; 34. ultrasonic tank; 4. mechanical arm; 41. liquid receiving plate; 411. clamping hole; 42. clamping block; 421. clamping block. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] An improved RCA cleaning process comprises the following steps: Preparation: Prepare the required chemical reagents, including deionized water, HNO3, HF, CH3COOH, H2SO4, etc., and ensure that all equipment and containers used are clean.

[0025] S1: Put the silicon wafer into the cleaning container 1, and immerse the cleaning container 1 in deionized water.

[0026] The purpose here is to remove impurities on the surface of the silicon wafer. Deionized water has a high purity and contains almost no impurities and ions. When the silicon wafer is placed in it, some soluble impurities, dust, particulate matter and other contaminants on the surface of the silicon wafer can be removed by soaking and rinsing, which plays a role of preliminary cleaning and creates better conditions for the subsequent formal cleaning steps. Because if there are contaminants on the surface of the silicon wafer, direct subsequent cleaning may cause the contaminants to spread or transfer to other parts during the cleaning process. Putting it in deionized water first can dissolve or suspend the contaminants in the water, reduce their residue and diffusion on the surface of the silicon wafer, and thus clean it more effectively.

[0027] In addition, silicon wafers may generate static electricity during processing and transportation, resulting in the adsorption of some charged particles on the surface. Deionized water can play a certain conductive role, helping to neutralize or eliminate static electricity on the surface of silicon wafers, and reduce the impact of static electricity on the cleaning process and silicon wafer quality. At the same time, soaking in deionized water can make the surface of silicon wafers fully moist, which is conducive to the subsequent cleaning liquid to better contact and act with the surface of silicon wafers, improving the cleaning effect and efficiency. For example, in some cleaning processes, first soaking in deionized water and then using mixed acid for cleaning can more thoroughly remove various pollutants on the surface of silicon wafers. S2: Take out the cleaning container 1, transfer it to a mixed acid solution, and soak it for 40s~60s at -10℃~-5℃; wherein the mixed acid solution contains HNO3 with a concentration of 65%~68%, HF with a concentration of 40%~50%, CH3COOH with a concentration of 95%~98% and H2SO4 with a volume ratio of 3:1:1:3.

[0028] It should be noted that, in the actual cleaning process, the concentrations of the mixed acid solution, the temperatures of the solutions, and the frequency of the ultrasonic cleaning described below can be flexibly adjusted according to different processes, and the embodiments of the present application do not impose specific restrictions on this.

[0029] The above-mentioned mixed acid solution is mainly used to remove SiO2, metal ions and organic molecules on the surface of silicon wafers.

[0030] Among them, CH3COOH can form a complex with metal ions on the surface of the silicon wafer. The carboxyl group (-COOH) in CH3COOH can react with the metal ions to form a stable complex. The solubility of this complex in the cleaning solution is relatively high, so that the metal ions can be removed from the surface of the silicon wafer.

[0031] In addition, the pH value of the mixed acid solution needs to be precisely controlled. CH3COOH, as a weak acid, can act as a buffer in the entire mixed acid solution. When the pH value of the mixed acid solution fluctuates due to other chemical reactions, CH3COOH can release or absorb hydrogen ions (H + ), thereby maintaining a relatively stable pH value of the cleaning solution.

[0032] At the same time, since the silicon wafer surface has a certain degree of hydrophobicity, CH3COOH can improve the wettability of the mixed acid solution on the silicon wafer surface. CH3COOH molecules can be adsorbed on the silicon wafer surface, reducing the surface energy of the silicon wafer surface, allowing the mixed acid solution to spread better on the silicon wafer surface, thereby improving the cleaning efficiency and ensuring that all areas of the silicon wafer surface can be cleaned.

[0033] It is particularly important that after the mixed acid solution is cleaned, the presence of CH3COOH can form a protective film on the surface of the silicon wafer. This protective film can prevent the silicon wafer from being contaminated again by pollutants in the surrounding environment after being taken out of the mixed acid solution, such as dust and volatile organic compounds in the air. In addition, during the subsequent drying and processing process, this protective film can gradually evaporate and will not cause adverse effects on the surface of the silicon wafer.

[0034] H2SO4 can react chemically with some metals to generate corresponding sulfates. When removing metal from the surface of silicon wafers, it works synergistically with other solutions in the mixed acid solution to provide a certain chemical environment and reaction conditions for the entire metal removal process, which is more conducive to removing metal impurities in silicon wafers.

[0035] HF has a unique chemical etching ability for SiO2, which can dissolve and remove it, thereby effectively removing the oxide layer on the surface of the silicon wafer. This selective etching is very critical because it can accurately remove the oxide layer without significantly corroding the silicon substrate. Therefore, by controlling the parameters such as HF concentration, temperature and cleaning time, it is possible to achieve selective removal of silicon oxide, which helps to maintain the flatness and structural integrity of the silicon wafer surface.

[0036] HNO3 has strong oxidizing properties, and many metals will be oxidized in nitric acid to form soluble metal nitrates. Through this oxidation reaction, metal impurities are dissolved from the surface of the silicon wafer into the mixed acid solution and removed. HNO3 can convert these metal impurities into ionic form, making them easier to be cleaned from the surface of the silicon wafer.

[0037] In addition, HNO3 can react with organic matter, and some organic matter will be decomposed into small molecules under the strong oxidizing effect of HNO3, such as CO2, H2O, etc. For complex organic pollutants, the strong oxidizing property of HNO3 can destroy their molecular structure, turning them into small molecular fragments that are more soluble in water or other cleaning fluids, and then be cleaned away.

[0038] Therefore, by continuously adjusting the concentration and ratio of each solution, the mixed acid solution as described in the embodiment can be configured to thin the silicon wafer by 5um-8um, and at the same time remove SiO2, metal ions and organic molecules attached to the surface of the channel, thereby achieving the purpose of acid cleaning in RCA cleaning. The reaction formula of the main chemical reaction is: Si+4HNO3+6HF=H2SiF6+4NO2+4HO2 The generated substances such as H2SiF6, NO2 and HO2 can continue to react and decompose in the mixed acid solution to produce substances such as H2, O2 or solid impurities, and finally be further treated in the waste liquid.

[0039] The temperature during the entire cleaning process must take into account both the severity of the internal reaction of the solution and the volatilization characteristics of the acidic solution. Therefore, it is set at -10℃~-5℃ and immersed in the mixed acid solution for 40s~60s.

[0040] S3: Take the cleaning container 1 out of the mixed acid solution and rinse the silicon wafer with deionized water until all chemicals are rinsed away.

[0041] During the mixed acid solution cleaning process, the mixed acid solution reacts chemically with the pollutants on the surface of the silicon wafer. Although the mixed acid solution can remove many impurities, the mixed acid solution itself will remain on the surface of the silicon wafer after the reaction. If these residual solutions are not removed in time, when the silicon wafer enters the subsequent process steps, the residual solution may continue to react with the silicon wafer or other substances, affecting the performance of the silicon wafer. In addition, during the reaction of the mixed acid solution with the impurities on the surface of the silicon wafer, it may carry some newly generated impurities or impurities that have not reacted completely.

[0042] Therefore, the impurities carried by the mixed acid solution can be effectively washed away from the surface of the silicon wafer by rinsing with deionized water, thereby ensuring the cleanliness requirements of the silicon wafer surface in subsequent processes.

[0043] S4: Transfer the cleaning container 1 to an ultrasonic cleaner and clean it for 200s-300s at a cleaning frequency of 28KHZ-40KHZ.

[0044] The high-frequency vibration generated by ultrasound can make the cleaning liquid produce countless tiny bubbles. These bubbles will generate strong impact force in the process of formation, growth and rupture. This impact force can effectively remove particulate pollutants on the surface of silicon wafers. Such as tiny dust, metal particles, etc. Even some particles with strong adsorption force are more easily taken away by the cleaning liquid under the action of ultrasound. For organic pollutants on the surface of silicon wafers, ultrasound can promote the chemical reaction between the cleaning liquid and the organic pollutants. It can make the cleaning liquid better penetrate into the interface between the organic pollutants and the surface of the silicon wafer, accelerate the decomposition and dissolution process of the organic pollutants, and thus improve the efficiency and quality of cleaning.

[0045] The low-frequency cleaning frequency of 28KHZ~40KHZ used in this step is large, and the bubbles generated by low-frequency ultrasound are large, and the energy released when they burst is high, and they have a strong impact force. Therefore, it is more effective in removing large particle pollutants and some pollutants with strong adhesion on the surface of silicon wafers. This step is located after the mixed acid solution, and can completely remove impurities on the surface of silicon wafers.

[0046] S5: Take out the cleaning container 1, and take out the silicon wafer and put it into a dryer for drying until no moisture remains on the surface of the silicon wafer.

[0047] One embodiment of the dryer is a wafer carrier that is loaded into a wafer holder inside a cylindrical container. In the center of this cylindrical container is a row of perforated tubes that connect deionized water and hot ammonia. The spin drying process actually starts with rinsing the wafers as they rotate around a central column that sprays water. Then, as hot nitrogen sprays out of the central column, the spin dryer switches to high speed rotation, which shakes water off the surface of the wafer while the hot nitrogen helps remove small water droplets clinging to the wafer.

[0048] After the entire improved RCA cleaning process is completed, the silicon wafer is tested by an oscilloscope, and the test end of the oscilloscope probe is touched to the position on the silicon wafer where the leakage needs to be measured. If the silicon wafer has specific electrodes or pins for testing leakage, the probe should be connected to the corresponding position. Start the data acquisition function of the oscilloscope, measure the leakage of the silicon wafer, and observe the voltage waveform displayed on the oscilloscope screen. If there is leakage, a stable DC voltage or slight fluctuations may be seen. The temperature of the silicon wafer can be controlled by a high and low temperature box throughout the process.

[0049] According to the voltage value displayed on the oscilloscope, the leakage current can be calculated if the resistance of the silicon wafer and other related parameters are known. Then the result can be analyzed. The test data and results are shown in Table 1.

[0050] Table 1: As shown in the above table, after the two acid solutions that need to be added during pickling in the original RCA standard cleaning method are converted into the mixed acid solution described in the embodiment of the present application, the silicon wafer is rinsed with ultrasound and deionized water in the embodiment. The final test result meets the cleaning requirements, so that the mixed acid solution of the application can replace the existing two acid solutions. In this way, only one pickling step is required to achieve the original cleaning effect. While reducing the pickling steps, the use of chemical agents is reduced, the cost is reduced, and the cleaning quality can be guaranteed.

[0051] like Figure 1-Figure 6As shown, in order to cooperate with the above-mentioned cleaning process, an improved RCA cleaning equipment is also equipped, including an equipment body 100, and the equipment body 100 includes a control system, a liquid preparation and supply system, a liquid drainage system and a working cabin. A plurality of cleaning tanks are provided on the workbench of the working cabin. The equipment is suitable for any of the above-mentioned improved RCA cleaning processes; it also includes a cleaning container 1 adapted to the cleaning tank for holding silicon wafers, and a lifting mechanism 2 capable of transferring the cleaning container 1 to different cleaning tanks is fixed on the top of the working cabin. The cleaning tanks have four, namely, an immersion tank 31, a pickling tank 32, a rinse tank 33 and an ultrasonic tank 34. A robotic arm 4 is fixed to the side wall of the working cabin, and a liquid receiving plate 41 is fixed to the working end of the robotic arm 4. During the transfer of the cleaning container 1, the liquid receiving plate 41 is always horizontally located at its bottom.

[0052] The control system includes a temperature control system to control the temperature of the liquid in the cleaning tank to achieve the required cleaning temperature. The lighting system is equipped with dual-light fluorescent lighting on the top of the work area so that the operator can clearly observe the cleaning process during the cleaning process. It also includes an exhaust and air supply system with adjustable air volume, which is used to exhaust the waste gas and acid mist generated during the cleaning process, etc., to provide safety protection for the operator. A purification air supply device is installed on the top of the equipment to ensure air purification and air circulation inside the equipment.

[0053] The skeleton and shell of the equipment body 100 play the role of supporting and protecting the internal structure of the equipment. At the same time, considering that the equipment works in an acid corrosion environment for a long time, it needs to have corresponding corrosion resistance. In addition, the lower part of the equipment body 100 has pipelines for connecting various cleaning tanks, liquid distribution and supply systems, drainage systems, etc., and all process tanks, pipelines, and valve parts will be clearly labeled for easy operation and maintenance. Among them, the liquid pipeline needs to use corrosion-resistant PFA pipes, and the pure water pipeline uses white NPP spray pipes. The generated chemical corrosion waste liquid and flushing wastewater need to be discharged through dedicated pipelines.

[0054] Among them, the immersion tank 31 contains deionized pure water, the pickling tank 32 contains a mixed acid solution, the side wall of the rinse tank 33 is connected to the liquid distribution system and the drainage system through a spray device, and deionized water is sprayed for rinsing, and the ultrasonic tank 34 is connected to an ultrasonic device for further cleaning. During the cleaning process, the control system will automatically adjust the liquid distribution system and the drainage system to replace the solutions in several cleaning tanks. When the equipment is in use, after the silicon wafer is installed in the cleaning container 1, the cleaning container 1 is driven by the lifting mechanism 2 to enter different cleaning tanks in the order of the above-mentioned cleaning process. During the transfer process of the cleaning container 1, it is inevitable that waste liquid will drip. At this time, the robot arm 4 drives the liquid receiving plate 41 to always be horizontally located at its bottom, and the liquid receiving plate 41 is used to catch the fallen waste liquid to prevent the waste liquid from falling and contaminating the workbench.

[0055] The liquid receiving plate 41 itself can also be taken by the robot arm 4 into different cleaning tanks to be cleaned with deionized water. After the work is completed, the liquid receiving plate 41 preferably enters the immersion tank 31 and the rinse tank 33 for cleaning. After the cleaning is completed, it automatically returns to the side wall of the working cabin and vertically fits the side wall without interfering with other operations in the working cabin. The hoisting mechanism 2 and the robot arm 4 are both high-speed transfer equipment, which can ensure the overall cleaning efficiency.

[0056] like Figure 6 As shown, the liquid receiving plate 41 is an arc-shaped structure that is concave downward when in a horizontal state. In order to prevent collision between the cleaning container 1 and the liquid receiving plate 41, a certain safety distance is provided between the two. Therefore, when the waste liquid falls from the bottom of the cleaning container 1 onto the liquid receiving plate 41, it will splash around due to gravity. The arc-shaped liquid receiving plate 41 can make the splashed waste liquid fall in a parabolic curve along the side walls of the liquid receiving plate 41, which is more conducive to the centralized collection of the waste liquid after it falls.

[0057] like Figure 5 As shown, a snap-in hole 411 is provided on the outer edge of the liquid receiving plate 41, and the working end of the robot arm 4 is a clamping structure, which includes two clamping blocks 42 with adjustable spacing, and snap-in blocks 421 matching the snap-in holes 411 are fixed on the surfaces of the two clamping blocks 42 close to each other. The robot arm 4 is fixed to the liquid receiving plate 41 by respectively inserting the two snap-in blocks 421 into the two ends of the snap-in holes 411.

[0058] When the robot arm 4 needs to be connected to the liquid receiving plate 41, the distance between the two clamping blocks 42 is increased, the clamping hole 411 on the liquid receiving plate 41 is placed between the two clamping blocks 42 and aligned with the two clamping blocks 421, and the distance between the two clamping blocks 42 is reduced, so that the two clamping blocks 421 are respectively inserted into the two ends of the clamping hole 411. Thus, the liquid receiving plate 41 is connected to the robot arm 4. In this way, the robot arm 4 and the liquid receiving plate 41 are detachable structures, which can be easily replaced and can meet more different cleaning requirements.

[0059] like Figure 4 As shown, one embodiment of the cleaning container 1 is a square cylindrical structure, a plurality of strip positioning holes 11 arranged in parallel are opened on one side wall of the cleaning container 1, a plurality of strip insertion holes 12 are opened on the other three side walls corresponding to the strip positioning holes 11, and the three strip insertion holes 12 corresponding to the same strip positioning hole 11 are connected as a whole.

[0060] The cleaning container 1 is used to hold silicon wafers. There is a certain gap between the strip positioning holes 11 so as not to hinder the flushing of water flow. The silicon wafer is inserted from the strip insertion hole 12 until it stops and is positioned after penetrating the strip positioning hole 11. Since the three strip insertion holes 12 are connected as one, they are not restricted by the size of the silicon wafer. And during actual cleaning, the placement direction of the cleaning container 1 can be adjusted according to the actual situation, such as the position of the spray, so that the silicon wafer is placed vertically or horizontally to ensure higher cleaning efficiency. It is worth noting that due to the length limitation of the strip positioning hole 11, when the surface where the strip positioning hole 11 is located is at the bottom of the cleaning tank, the silicon wafer inside the cleaning container 1 will not pass through the side wall of the cleaning container 1 and contact the working part inside the cleaning tank, thereby preventing the silicon wafer from being damaged.

[0061] Furthermore, the number and type of reference silicon wafers may also use different cleaning containers 1 to adapt the entire cleaning process.

[0062] like Figure 1-Figure 2 As shown, a hook 21 is fixed to the lifting position of the lifting mechanism 2. Figure 4 As shown, the edges of the cleaning container 1 are provided with hooking grooves 13 that match the hooks 21. In this way, the cleaning container 1 placed in any direction can ensure that there is a hooking groove 13 on the side wall of its upper end surface, so as to facilitate the lifting of the lifting mechanism 2, and the hook 21 is a double-hook structure with an adjustable distance, and the double hooks are used to hook the two sides of the cleaning container 1 respectively. When the double hooks are inserted into the hooking grooves 13, the cleaning container 1 will not shake when moving up and down or left and right, making the entire transfer process more stable and the entire automated operation process more perfect. Preferably, the cleaning container 1 and the lifting mechanism 2 can be matched and replaced according to the different silicon wafers.

[0063] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An improved RCA cleaning process, characterized in that: The steps include: S1: placing a silicon wafer into a cleaning container (1), and immersing the cleaning container (1) in deionized water; S2: Take out the cleaning container (1), transfer it to the mixed acid solution, and soak it at -10°C to -5°C for 40s to 60s; S3: taking the cleaning container (1) out of the mixed acid solution and rinsing the silicon wafer with deionized water until all chemicals are rinsed away; S4: transferring the cleaning container (1) to an ultrasonic cleaner and cleaning it at a cleaning frequency of 28 kHz to 40 kHz for 200 s to 300 s; S5: Take out the cleaning container (1), take out the silicon wafer and place it in a dryer for drying until no moisture remains on the surface of the silicon wafer.

2. An improved RCA cleaning process according to claim 1, characterized in that: The mixed acid solution comprises HNO3 with a concentration of 65% to 68%, HF with a concentration of 40% to 50%, CH3COOH with a concentration of 95% to 98% and H2SO4 with a concentration of 95% to 98%, and the volume ratio of the four is 3:1:1:

3.

3. An improved RCA cleaning device, comprising a device body (100), wherein the device body (100) comprises a control system, a liquid preparation and supply system, a liquid discharge system and a working cabin, wherein a plurality of cleaning slots are provided on a working table of the working cabin, wherein: The equipment is applicable to any one of the improved RCA cleaning processes described in claims 1 to 2; It also includes a cleaning container (1) adapted to the cleaning tank and used to hold silicon wafers. A lifting mechanism (2) capable of transferring the cleaning container (1) to different cleaning tanks is fixed on the top of the working cabin. The cleaning tanks have four, namely, an immersion tank (31), a pickling tank (32), a rinsing tank (33) and an ultrasonic tank (34). A mechanical arm (4) is fixed on the side wall of the working cabin. A liquid receiving plate (41) is fixed to the working end of the mechanical arm (4). During the transfer of the cleaning container (1), the liquid receiving plate (41) is always horizontally located at the bottom thereof.

4. The improved RCA cleaning device according to claim 3, characterized in that: The liquid receiving plate (41) is an arc-shaped structure that is concave downwards when in a horizontal state.

5. The improved RCA cleaning device according to claim 3, characterized in that: A clamping hole (411) is provided on the outer edge of the liquid receiving plate (41); the working end of the mechanical arm (4) is a clamping structure, the clamping structure comprising two clamping blocks (42) with adjustable spacing, and clamping blocks (421) matching the clamping holes (411) are fixed on surfaces of the two clamping blocks (42) close to each other; the mechanical arm (4) is fixed to the liquid receiving plate (41) by respectively inserting the two clamping blocks (421) into the two ends of the clamping holes (411).

6. The improved RCA cleaning device according to claim 3, characterized in that: The cleaning container (1) is a square cylindrical structure. A plurality of strip-shaped positioning holes (11) arranged in parallel are provided on one side wall of the cleaning container (1), and a plurality of strip-shaped insertion holes (12) corresponding to the strip-shaped positioning holes (11) are provided on the other three side walls, and the three strip-shaped insertion holes (12) corresponding to the same strip-shaped positioning hole (11) are connected as a whole.

7. The improved RCA cleaning device according to claim 3, characterized in that: A lifting hook (21) is fixed to the lifting position of the lifting mechanism (2), and a hooking groove (13) matching the lifting hook (21) is provided on the edge of the cleaning container (1).

8. The improved RCA cleaning device according to claim 7, characterized in that: The hook (21) is a double hook structure with an adjustable distance, and the double hooks respectively hook the two sides of the cleaning container (1).

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