Chemical cleaning methods for particles and metal residues on the surface of tank-type compound wafers

Abstract

The present invention relates to a chemical cleaning method for particles and metal residues on the surface of a tank-type compound wafer, wherein the wafer is sequentially subjected to acid cleaning, SPM cleaning, HQDR cleaning, SC1 cleaning, QDR cleaning, SC1 cleaning, QDR cleaning, SC2 cleaning, QDR cleaning, DHF cleaning, HQDR cleaning, HOFR cleaning, and drying. The present invention optimizes the design of each process, and the cleaning process is short and easy to operate; the present invention can specifically remove particles of different sizes step by step, graded, and step by step, reduce the residual amount of surface particles, dirt, and metal residues, and greatly improve the quality of the wafer. Finally, it can be achieved that the total metal content on the surface of the wafer after cleaning is ≤2E10atomS / cm2, and the metals include 16 categories (Na, Al, K, Ca, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Au, Ag, V, Hg).

Description

Technical Field

[0001] The invention relates to a chemical cleaning method for surface particles and metal residues of a tank-type compound wafer, belonging to the technical field of wafer chemical cleaning. Background Art

[0002] Semiconductor wafers are often cleaned chemically. Chemical cleaning refers to the process of using various chemical reagents and organic solvents to react or dissolve impurities and oils adsorbed on the surface of the wafer to be cleaned, so that the impurities are desorbed from the surface of the wafer to be cleaned, and then rinsed with a large amount of high-purity hot and cold deionized water to obtain a clean surface. Chemical cleaning can be divided into wet chemical cleaning and dry chemical cleaning, among which wet chemical cleaning still occupies a dominant position in semiconductor cleaning processes.

[0003] Wet chemical cleaning including solution immersion

[0004] (1) Solution immersion method. Solution immersion method is a method of immersing the wafer in a chemical solution to remove surface contamination. It is the most commonly used method in wet chemical cleaning. Different solutions can be used to remove different types of contaminants on the wafer surface, such as using organic solvents to remove organic pollutants and using RCA solutions to remove organic, inorganic and metal ion impurities. Usually this method cannot completely remove impurities on the wafer surface, so physical measures such as heating, ultrasound, and stirring are often used in conjunction with immersion.

[0005] (2) Ultrasonic cleaning. Ultrasonic cleaning is a cleaning method widely used in the semiconductor industry. Its advantages are: good cleaning effect, simple operation, and can also clean complex devices and containers. This cleaning method is that under the action of strong ultrasonic waves (the commonly used ultrasonic frequency is 20-40kHz), sparse parts and dense parts will be generated inside the liquid medium. The sparse parts will produce nearly vacuum cavities. When the cavities disappear, strong local pressure will be generated near them, breaking the chemical bonds in the molecules and desorbing the impurities on the surface of the wafer. The effect of ultrasonic cleaning is related to the ultrasonic conditions (such as temperature, pressure, ultrasonic frequency, power, etc.), and is mostly used to remove large pieces of pollution and particles attached to the surface of the wafer.

[0006] (3) Megasonic cleaning. Megasonic cleaning not only has the advantages of ultrasonic cleaning, but also overcomes its shortcomings. Megasonic cleaning is a process of cleaning wafers by combining the high-energy (850kHz) frequency vibration effect with the chemical reaction of chemical cleaning agents. During cleaning, the solution molecules are accelerated by the megasonic waves (the maximum instantaneous speed can reach 30cm / s), and the high-speed fluid waves continuously impact the wafer surface, so that the pollutants and fine particles attached to the wafer surface are forcibly removed and enter the cleaning solution. This method can simultaneously play the role of mechanical wiping and chemical cleaning. At present, the megasonic cleaning method has become an effective method for cleaning polishing wafers.

[0007] However, the above cleaning methods are relatively single; therefore, it is necessary to develop a new cleaning method that combines multiple cleaning methods. Summary of the invention

[0008] In view of the shortcomings of the prior art, the present invention provides a chemical cleaning method for particles and metal residues on the surface of a tank-type compound wafer. The specific technical scheme is as follows:

[0009] A chemical cleaning method for particles and metal residues on the surface of a tank-type compound wafer comprises the following steps:

[0010] The wafer is sequentially subjected to acid cleaning, SPM cleaning, HQDR cleaning, SC1 cleaning, QDR cleaning, SC1 cleaning, QDR cleaning, SC2 cleaning, QDR cleaning, DHF cleaning, HQDR cleaning, HOFR cleaning, and drying;

[0011] The cleaning liquid for pickling is a sulfuric acid solution;

[0012] The cleaning solution for SPM cleaning is a mixture of sulfuric acid and hydrogen peroxide;

[0013] The cleaning solution for HQDR cleaning is hot deionized water;

[0014] The cleaning solution for SC1 cleaning is a mixture of ammonia, hydrogen peroxide and water;

[0015] The cleaning solution for the QDR cleaning is deionized water;

[0016] The cleaning solution of the SC2 cleaning is a mixture of hydrochloric acid, hydrogen peroxide and water;

[0017] The cleaning solution of the DHF cleaning is hydrofluoric acid;

[0018] The cleaning solution for HOFR cleaning is deionized water.

[0019] As an improvement of the above technical solution, the acid pickling temperature is 100-150°C, the SPM cleaning temperature is 100-150°C, the HQDR cleaning temperature is 60-80°C, the SC1 cleaning temperature is 60-95°C, the QDR cleaning temperature is 15-25°C, the SC2 cleaning temperature is 60-95°C, the DHF cleaning temperature is 15-25°C, and the HOFR cleaning temperature is 60-80°C.

[0020] As an improvement of the above technical solution, the pickling, SPM cleaning, SC1 cleaning, SC2 cleaning, and DHF cleaning all adopt a cleaning liquid circulation mode, a filter is used to filter the cleaning liquid during the circulation process, and an online concentration meter is used to monitor the concentration of the cleaning liquid online; when the concentration of the cleaning liquid is lower than the set value, a quantitative pump is used to replenish the cleaning liquid. In addition to the quantitative pump, flow meters or weighing methods can also be used.

[0021] As an improvement of the above technical solution, the SC1 cleaning method adopts complex frequency ultrasonic cleaning with multiple resonance frequencies.

[0022] As an improvement of the above technical solution, the cleaning methods of the SC2 cleaning and the HOFR cleaning are both megasonic cleaning.

[0023] As an improvement of the above technical solution, the drying temperature is 30-80°C.

[0024] As an improvement of the above technical solution, in the cleaning solution of the SC2 cleaning, the volume ratio of hydrogen chloride, hydrogen peroxide and water is 1:1.1:(11-13).

[0025] As an improvement of the above technical solution, a rotating mechanism for rotating the cleaning basket is provided in the cleaning tank of the QDR cleaning.

[0026] As an improvement of the above technical solution, the complex frequency ultrasonic cleaning has two resonance frequencies, which are 51.3 kHz and 81.2 kHz respectively.

[0027] As an improvement of the above technical solution, the frequency of the megasonic cleaning is 950-1000 kHz.

[0028] All cleaning fluids have online concentration analysis functions, such as using an online concentration meter to monitor the concentration of the cleaning fluid online; when the concentration of the cleaning fluid is lower than the set value, a quantitative pump is used to replenish the cleaning fluid (if the cleaning fluid is hydrofluoric acid, when replenishment is required, a quantitative pump can be used to replenish high-concentration hydrofluoric acid) to ensure the uniformity of the cleaning fluid concentration in the process tank, thereby helping to increase the yield of the wafer. The traditional approach is to use the cleaning time and batches for quantitative and regular replenishment, which results in uneven cleaning fluid concentration in the later stage, causing a decrease in the yield of the wafer.

[0029] 1. The present invention preferably adopts pickling, which can remove organic matter and part of inorganic matter on the surface of the wafer.

[0030] 2. In the present invention, SPM cleaning is used to remove most of the organic pollutants on the wafer surface, especially the organic film, so that other cleaning solutions can be used to further deeply clean the wafer surface.

[0031] The cleaning solution of the SPM cleaning is a mixture of sulfuric acid and hydrogen peroxide; preferably, 98% sulfuric acid and 30% hydrogen peroxide are mixed in proportion, such as a volume ratio of 5:1. In the present invention, the temperature of the SPM cleaning is preferably 100-150°C. In the present invention, the wafer is preferably circulated and rinsed by a circulation pump during the SPM cleaning process.

[0032] 3. HQDR cleaning is more effective than QDR cleaning at room temperature and improves the water washing effect more quickly. In the present invention, the HQDR cleaning is used to wash away large particles that have been oxidized during the SPM cleaning process, such as removing particles larger than 5 μm, and washing away residual SPM residual liquid and dirty particles. At the same time, due to the design of the subsequent process, in this step, there is no need to use ultrasound to improve the cleaning effect. Even if there may be some larger dirty areas, they will be washed away in the subsequent cleaning. The cleaning temperature is preferably 60-80°C, and the cleaning time is 5 minutes.

[0033] The temperature of the HQDR tank after the SPM cleaning process also has an important function, which is to prevent the wafer from being transferred from the high-temperature SPM tank to the QDR tank with a large temperature difference. In order to prevent the instantaneous temperature difference from causing the wafer to crack, the water temperature is increased.

[0034] 4. In the present invention, the SC1 cleaning is micro-etching and complex cleaning. In the present invention, the temperature of the SC1 cleaning is preferably 60-95°C; multiple frequency ultrasonic cleaning is used during cleaning, and the cleaning effect is significantly better than conventional ultrasonic cleaning; the cleaning frequency is preferably 40-200kHz.

[0035] In the present invention, the SC1 cleaning can slowly dissolve the dirty particles, mainly removing particles with a particle size greater than 0.5 μm; accordingly, the number of particles with a particle size less than 0.5 μm will also increase; due to the occurrence of complexation reaction, some metals can be effectively removed, thus forming a clean oxide layer.

[0036] In the present invention, there is still a hydrophobic organic film on the surface of the wafer after SPM cleaning, which cannot be completely cleaned by HQDR cleaning. Only by combining SC1 cleaning with multi-frequency ultrasonic cleaning can there be a super strong cleaning effect for removing surface organic films and adhered dirt, especially for wafers with serious organic pollution, which require a combination of 100-150°C SPM cleaning and multi-frequency ultrasonic SC1 cleaning. Megasonic cleaning cannot be used in this step. If the megasonic cleaning equipment is forcibly installed, it will cause disordered particle distribution on the surface and sub-surface of the wafer, and will increase the difficulty of subsequent DHF cleaning.

[0037] The effect of ultrasonic cleaning is closely related to the selected ultrasonic frequency. Low frequency is good for cleaning large particles of dirt, while high frequency is good for deep cleaning of small particles that are difficult to remove locally. Currently, most ultrasonic cleaning equipment for wafers on the market uses a single frequency.

[0038] 5. In the present invention, the QDR cleaning is mainly used to remove particles of 1 to 5 microns, especially to wash away the particles that were broken by the SC1 cleaning with complex frequency ultrasound in the previous step. Since the SC1 cleaning with complex frequency ultrasound has been used in the previous step, the QDR cleaning only needs conventional cleaning to meet the cleaning needs, and the cleaning temperature is also room temperature.

[0039] 6. Performing SC1 cleaning with multiple frequency ultrasound again and then using QDR cleaning can further improve the cleaning effect.

[0040] 7. In the present invention, the SC2 cleaning is an ion complex cleaning, which is mainly used to generate soluble ion complexes, remove alkali metal ions and metal hydroxides, dissolve residual metals, and form a protective passivated hydrated oxide film. In the present invention, the temperature of the SC2 cleaning is the same as that of the SC1 cleaning. Since in the present invention, only two SC1 cleanings are performed and then the SC2 cleaning is immediately performed, and there is no DHF cleaning transition in between, therefore, in the present invention, the SC2 cleaning needs to use megasonic cleaning technology to further improve the cleaning effect. If conventional ultrasonic cleaning technology or multi-frequency ultrasonic cleaning technology is used in the SC2 cleaning, the cleaning requirements cannot be met.

[0041] 8. After SC2 cleaning, QDR cleaning is used mainly to wash away the particles that were broken in the previous step.

[0042] A rotation function can be added to the cleaning tank of QDR cleaning to avoid particles agglomerating at the edge of the wafer, while also reducing the requirements for deionization flow and reducing energy costs. Among them, a rotating mechanism for rotating the cleaning basket is provided in the cleaning tank of QDR cleaning. When cleaning multiple wafers at the same time, it is usually necessary to place the wafers in the cleaning basket.

[0043] 9. In the present invention, the DHF cleaning is a micro-etching stripping cleaning, which mainly micro-etches the dirt particles embedded in the wafer surface and the particles in the shallow oxide layer on the surface, and further cleans the sub-surface of the wafer. In the present invention, hydrofluoric acid can corrode the wafer surface, accelerate the exposure of the wafer sub-surface, and corrode and strip the silicon dioxide thermal growth layer containing metal or non-metallic contaminants.

[0044] Because it is a very reasonable design to completely clean the wafer surface first and then perform DHF cleaning on the wafer sub-surface, otherwise it is easy to cause the wafer surface and sub-surface to be incompletely cleaned. However, it is a difficult point to clean the wafer surface only by using SPM cleaning, SC1 cleaning (repeated only twice), SC2 cleaning and other cleaning processes. If DHF cleaning is inserted in the repeated process of SC1 cleaning, since SC1 cleaning contains ammonia water and DHF cleaning uses hydrofluoric acid, DHF cleaning will reduce the cleaning effect of SC1 cleaning, especially low-concentration SC1 cleaning.

[0045] If ultrasonic assisted cleaning is used in SC2 cleaning, it will accelerate local micro-etching and produce a certain degree of micro-roughness, which will not only cause serious corrosion on the chip surface, but also make it more difficult to remove particles adhering to the surface.

[0046] It is difficult to remove SC2 stains by simply using QDR cleaning, HQDR cleaning or DIW cleaning after SC2 cleaning, regardless of whether ultrasonic assisted cleaning is used.

[0047] 10. HQDR cleaning is mainly used to wash away the particles generated in the previous step, and then HOFR cleaning is required under the action of megasonics for deep cleaning. HOFR cleaning is to continuously pass 60-80°C deionized water into the overflow tank, and megasonics-assisted cleaning is used to finally deeply clean the surface of the chip, especially to completely clean the residual drug stains from the previous DHF cleaning.

[0048] Compared with QDR cleaning, HOFR cleaning with megasonic assisted cleaning is more effective in cleaning residual DHF stains on the wafer surface.

[0049] 11. Finally, the drying temperature is 30-80°C, and hot nitrogen can be used for drying. In addition to hot nitrogen drying, centrifugal drying can also be selected. The choice of drying process mainly depends on factors such as the material and internal structure of the compound wafer.

[0050] The invention has the function of water saving and reuse, which greatly reduces the usage of deionized water.

[0051] The combination of complex frequency ultrasound (40-200kHz) and secondary megasonic waves (950-1000kHz) can more effectively remove metal particles of different particle sizes.

[0052] The cleaning liquid used for cleaning is sulfuric acid solution, a mixture of sulfuric acid and hydrogen peroxide, deionized water, a mixture of ammonia, hydrogen peroxide and water, a mixture of hydrochloric acid, hydrogen peroxide and water, hydrofluoric acid, etc., which can oxidize, dissolve, and complex to remove organic and inorganic pollutants and metal ions on the surface of the wafer; the unique cleaning process of the present invention is particularly effective in removing metal particles. The final cleaning effect that can be achieved is:

[0053] Particle index ≥ 0.2μm 10EA, particle index ≥ 0.16μm 20EA. Among them, 0.2μm 10EA means that the particle contamination degree (≥ 0.2 microns) on the wafer surface can be less than 10 particles / piece. The rest are similar.

[0054] Beneficial effects of the present invention:

[0055] Compared with the prior art, the present invention has a short cleaning process and is easy to operate through the optimization design of each process. The present invention can remove particles of different sizes in a targeted, graded and level-by-level manner, reduce the residual amount of surface particles, dirt and metal residues, and greatly improve the quality of the wafer. The final result is: the total metal content on the surface of the cleaned wafer is ≤2E10atomS / cm 2 , metals include 16 categories (Na, Al, K, Ca, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Au, Ag, V, Hg). BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 FIG. 1 is a graph showing the cleaning frequency and removal rate of cleaning process 1. FIG. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0058] Example 1

[0059] The chemical cleaning method for the surface particles and metal residues of the tank-type compound wafer comprises the following steps:

[0060] The wafer is sequentially acid-washed, SPM-washed, HQDR-washed, SC1-washed, QDR-washed, SC1-washed, QDR-washed, SC2-washed, QDR-washed, DHF-washed, HQDR-washed, HOFR-washed, and dried.

[0061] The cleaning liquid of the pickling is a sulfuric acid solution, and the temperature of the pickling is 100°C; the cleaning liquid of the SPM cleaning is a mixture of sulfuric acid and hydrogen peroxide, and the temperature of the SPM cleaning is 100°C; the cleaning liquid of the HQDR cleaning is hot deionized water, and the temperature of the HQDR cleaning is 60°C; the cleaning liquid of the SC1 cleaning is a mixture of ammonia water, hydrogen peroxide and water, and the temperature of the SC1 cleaning is 60°C; the cleaning liquid of the QDR cleaning is deionized water, and the temperature of the QDR cleaning is 15°C; the cleaning liquid of the SC2 cleaning is a mixture of hydrochloric acid, hydrogen peroxide and water, and the temperature of the SC2 cleaning is 60°C; the cleaning liquid of the DHF cleaning is hydrofluoric acid, and the temperature of the DHF cleaning is 15°C; the cleaning liquid of the HOFR cleaning is deionized water, and the cleaning temperature of the HOFR cleaning is 60°C.

[0062] Among them, the acid cleaning, SPM cleaning, SC1 cleaning, SC2 cleaning, and DHF cleaning all adopt a cleaning liquid circulation mode. During the cleaning liquid circulation process, a filter is used for filtration, and an online concentration meter is used to monitor the concentration of the cleaning liquid online; when the concentration of the cleaning liquid is lower than the set value, a quantitative pump is used to replenish the cleaning liquid. The cleaning method of the SC1 cleaning adopts complex frequency ultrasonic cleaning with multiple resonant frequencies. The cleaning methods of the SC2 cleaning and HOFR cleaning both adopt megasonic cleaning. In the cleaning liquid of the SC2 cleaning, the volume ratio of hydrogen chloride, hydrogen peroxide, and water is 1:1.1:11. The drying temperature is 30°C.

[0063] After cleaning, the particles on the surface of the wafer are tested to meet the particle index:

[0064] Particle index ≥ 0.2μm 10EA, particle index ≥ 0.16μm 20EA; total metal content on the surface of the cleaned wafer ≤ 2E10 atoms / cm 2 , metals include 16 categories (Na, Al, K, Ca, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Au, Ag, V, Hg).

[0065] Example 2

[0066] The chemical cleaning method for the surface particles and metal residues of the tank-type compound wafer comprises the following steps:

[0067] The wafer is sequentially acid-washed, SPM-washed, HQDR-washed, SC1-washed, QDR-washed, SC1-washed, QDR-washed, SC2-washed, QDR-washed, DHF-washed, HQDR-washed, HOFR-washed, and dried.

[0068] The cleaning liquid of the pickling is a sulfuric acid solution, and the temperature of the pickling is 130°C; the cleaning liquid of the SPM cleaning is a mixture of sulfuric acid and hydrogen peroxide, and the temperature of the SPM cleaning is 130°C; the cleaning liquid of the HQDR cleaning is hot deionized water, and the temperature of the HQDR cleaning is 70°C; the cleaning liquid of the SC1 cleaning is a mixture of ammonia water, hydrogen peroxide and water, and the temperature of the SC1 cleaning is 80°C; the cleaning liquid of the QDR cleaning is deionized water, and the temperature of the QDR cleaning is 20°C; the cleaning liquid of the SC2 cleaning is a mixture of hydrochloric acid, hydrogen peroxide and water, and the temperature of the SC2 cleaning is 80°C; the cleaning liquid of the DHF cleaning is hydrofluoric acid, and the temperature of the DHF cleaning is 20°C; the cleaning liquid of the HOFR cleaning is deionized water, and the cleaning temperature of the HOFR cleaning is 70°C.

[0069] Among them, the acid cleaning, SPM cleaning, SC1 cleaning, SC2 cleaning, and DHF cleaning all adopt a cleaning liquid circulation mode. During the cleaning liquid circulation process, a filter is used for filtration, and an online concentration meter is used to monitor the concentration of the cleaning liquid online; when the concentration of the cleaning liquid is lower than the set value, a quantitative pump is used to replenish the cleaning liquid. The cleaning method of the SC1 cleaning adopts complex frequency ultrasonic cleaning with multiple resonant frequencies. The cleaning methods of the SC2 cleaning and HOFR cleaning both adopt megasonic cleaning. In the cleaning liquid of the SC2 cleaning, the volume ratio of hydrogen chloride, hydrogen peroxide, and water is 1:1.1:12. The drying temperature is 60°C.

[0070] After cleaning, the particles on the surface of the wafer are tested to meet the particle index:

[0071] Particle index ≥ 0.2μm 10EA, particle index ≥ 0.16μm 20EA; total metal content on the surface of the cleaned wafer ≤ 2E10 atoms / cm 2 , metals include 16 categories (Na, Al, K, Ca, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Au, Ag, V, Hg).

[0072] Example 3

[0073] The chemical cleaning method for the surface particles and metal residues of the tank-type compound wafer comprises the following steps:

[0074] The wafer is sequentially acid-washed, SPM-washed, HQDR-washed, SC1-washed, QDR-washed, SC1-washed, QDR-washed, SC2-washed, QDR-washed, DHF-washed, HQDR-washed, HOFR-washed, and dried.

[0075] The cleaning liquid of the acid pickling is a sulfuric acid solution, and the temperature of the acid pickling is 150°C; the cleaning liquid of the SPM cleaning is a mixture of sulfuric acid and hydrogen peroxide, and the temperature of the SPM cleaning is 150°C; the cleaning liquid of the HQDR cleaning is hot deionized water, and the temperature of the HQDR cleaning is 80°C; the cleaning liquid of the SC1 cleaning is a mixture of ammonia water, hydrogen peroxide and water, and the temperature of the SC1 cleaning is 95°C; the cleaning liquid of the QDR cleaning is deionized water, and the temperature of the QDR cleaning is 25°C; the cleaning liquid of the SC2 cleaning is a mixture of hydrochloric acid, hydrogen peroxide and water, and the temperature of the SC2 cleaning is 95°C; the cleaning liquid of the DHF cleaning is hydrofluoric acid, and the temperature of the DHF cleaning is 25°C; the cleaning liquid of the HOFR cleaning is deionized water, and the cleaning temperature of the HOFR cleaning is 80°C.

[0076] Among them, the acid cleaning, SPM cleaning, SC1 cleaning, SC2 cleaning, and DHF cleaning all adopt a cleaning liquid circulation mode. During the cleaning liquid circulation process, a filter is used for filtration, and an online concentration meter is used to monitor the concentration of the cleaning liquid online; when the concentration of the cleaning liquid is lower than the set value, a quantitative pump is used to replenish the cleaning liquid. The cleaning method of the SC1 cleaning adopts complex frequency ultrasonic cleaning with multiple resonant frequencies. The cleaning methods of the SC2 cleaning and HOFR cleaning both adopt megasonic cleaning. In the cleaning liquid of the SC2 cleaning, the volume ratio of hydrogen chloride, hydrogen peroxide, and water is 1:1.1:13. The drying temperature is 80°C.

[0077] After cleaning, the particles on the surface of the wafer are tested to meet the particle index:

[0078] Particle index ≥ 0.2μm 10EA, particle index ≥ 0.16μm 20EA; total metal content on the surface of the cleaned wafer ≤ 2E10 atoms / cm 2 , metals include 16 categories (Na, Al, K, Ca, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Au, Ag, V, Hg).

[0079] 《Test for characterization of particle cleaning effect》

[0080] 1. Coat 40nm (60, 80, 100, 200nm) polystyrene latex particles on a 6-inch wafer to prepare the wafer to be cleaned.

[0081] 2. Clean according to different cleaning processes, and the cleaning time is 1 hour.

[0082] 3. The removal rate is calculated by measuring the number of particles on the wafer using a particle measuring instrument, and the values ​​after and before cleaning.

[0083] Cleaning process 1: SC1 cleaning is used, ultrasonic assisted cleaning is used during cleaning, and the removal rate curve is shown in the case of a cleaning frequency of 40 to 200 kHz. Figure 1 . Figure 1 The curve at 40nm in the figure represents the removal curve of 40nm polystyrene latex particles. Figure 1 The curve at 200 nm in the figure represents the removal curve for 200 nm polystyrene latex particles.

[0084] Depend on Figure 1 It can be seen that low frequency is beneficial to the cleaning of large dirty particles (such as particles with a diameter of 200nm), while high frequency is beneficial to the deep cleaning of small particles (such as particles with a diameter of 40nm) that are difficult to remove locally. Figure 1 It can be seen that for comprehensive cleaning effect, the cleaning frequency can be selected within the range of 40 to 100 kHz.

[0085] Cleaning process 2: SC1 cleaning was used, and a complex frequency ultrasonic cleaning with two resonance frequencies was used. The complex frequency ultrasonic cleaning had two resonance frequencies, 51.3 kHz and 81.2 kHz. The removal rates are shown in Table 1.

[0086] Table 1

[0087] Particle size 40nm 60nm 80nm 100nm 200nm Removal rate 98.2％ 98.7％ 98.5％ 98.9％ 99.1％

[0088] As can be seen from Table 1, the use of multi-frequency ultrasonic cleaning can clean both large and small dirt particles, and the removal rate is high, exceeding 98%.

[0089] Cleaning process 3: SC1 cleaning is adopted, and a complex frequency ultrasonic cleaning with two resonance frequencies is adopted. The complex frequency ultrasonic cleaning has two resonance frequencies, and the two resonance frequencies are shown in Table 2, and the corresponding removal rates are also shown in Table 3.

[0090] Table 2

[0091]

[0092] Table 3

[0093] Particle size 40nm 60nm 80nm 100nm 200nm Group 1 removal rate 85.1％ 88.3％ 91.5％ 96.2％ 97.8％ Group 2 removal rate 86.6％ 88.9％ 92.1％ 95.5％ 97.1％ Group 3 removal rate 88.5％ 89.9％ 90.2％ 95.0％ 95.8％ Group 4 removal rate 81.5％ 85.7％ 93.8％ 97.1％ 96.6％ Group 5 removal rate 90.3％ 92.5％ 89.8％ 95.3％ 96.6％ Group 6 removal rate 86.7％ 88.1％ 91.5％ 92.1％ 93.5％ Group 7 removal rate 93.8％ 95.1％ 87.3％ 92.2％ 90.2％ Group 8 removal rate 95.2％ 95.9％ 86.2％ 93.6％ 91.5％

[0094] It can be seen from Table 2 and Table 3 that when there are two resonant frequencies, the lower the frequency in the low frequency band, the better it is, nor the higher the frequency is; the lower the frequency in the high frequency band, the better it is, nor the higher the frequency is. In the process of complex frequency ultrasonic cleaning, the appropriate resonant frequency should be found within the frequency range of 40 to 200 kHz so that the two resonant frequencies can play a synergistic role.

[0095] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A chemical cleaning method for particles and metal residues on the surface of a tank-type compound wafer, characterized in that The following steps are involved: The wafer is sequentially subjected to acid cleaning, SPM cleaning, HQDR cleaning, SC1 cleaning, QDR cleaning, SC1 cleaning, QDR cleaning, SC2 cleaning, QDR cleaning, DHF cleaning, HQDR cleaning, HOFR cleaning, and drying; The cleaning liquid for pickling is a sulfuric acid solution; The cleaning solution for SPM cleaning is a mixture of sulfuric acid and hydrogen peroxide; The cleaning solution for HQDR cleaning is hot deionized water; The cleaning solution for SC1 cleaning is a mixture of ammonia, hydrogen peroxide and water; The cleaning solution for the QDR cleaning is deionized water; The cleaning solution of the SC2 cleaning is a mixture of hydrochloric acid, hydrogen peroxide and water; The cleaning solution of the DHF cleaning is hydrofluoric acid; The cleaning solution for HOFR cleaning is deionized water; The SC1 cleaning method uses complex frequency ultrasonic cleaning with multiple resonance frequencies; The complex frequency ultrasonic cleaning has two resonant frequencies, 51.3kHz and 81.2kHz; The cleaning methods of the SC2 cleaning and HOFR cleaning both adopt megasonic cleaning; The frequency of the megasonic cleaning is 950-1000 kHz.

2. The method for chemically cleaning particles and metal residues on the surface of a bath-type compound wafer according to claim 1, characterized in that: The temperature of the acid pickling is 100~150℃, the temperature of the SPM cleaning is 100~150℃, the temperature of the HQDR cleaning is 60~80℃, the temperature of the SC1 cleaning is 60~95℃, the temperature of the QDR cleaning is 15~25℃, the temperature of the SC2 cleaning is 60~95℃, the temperature of the DHF cleaning is 15~25℃, and the cleaning temperature of the HOFR cleaning is 60~80℃.

3. The method for chemically cleaning particles and metal residues on the surface of a bath-type compound wafer according to claim 1, characterized in that: The acid cleaning, SPM cleaning, SC1 cleaning, SC2 cleaning and DHF cleaning all adopt a cleaning liquid circulation mode. During the cleaning liquid circulation process, a filter is used for filtering, and an online concentration meter is used to monitor the concentration of the cleaning liquid online; when the concentration of the cleaning liquid is lower than the set value, a quantitative pump is used to replenish the cleaning liquid.

4. The method for chemically cleaning particles and metal residues on the surface of a bath-type compound wafer according to claim 1, characterized in that: The drying temperature is 30-80°C.

5. The method for chemically cleaning particles and metal residues on the surface of a bath-type compound wafer according to claim 1, characterized in that: In the cleaning solution of the SC2 cleaning, the volume ratio of hydrochloric acid, hydrogen peroxide and water is 1:1.1:(11-13).

6. The method for chemically cleaning particles and metal residues on the surface of a bath-type compound wafer according to claim 1, characterized in that: A rotating mechanism for rotating the cleaning basket is provided in the cleaning tank of the QDR cleaning.

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