Wafer cleaning solution and cleaning method

Abstract

The invention relates to a wafer cleaning solution and a cleaning method, the cleaning solution is used for an SC-2 cleaning process, and the cleaning solution comprises hydrochloric acid, hydrogen peroxide and deionized water; wherein the pH value of the cleaning solution is greater than 2. According to the invention, particulate matters can be effectively prevented from depositing on the surface of the wafer, so that the deposition quantity of the particulate matters on the surface of the wafer is reduced, and the cleaning effect on the wafer is improved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and more specifically to a wafer cleaning solution and a cleaning method. Background Art

[0002] The goal of the wafer cleaning process is to remove chemical and particulate impurities without altering or damaging the wafer surface, i.e., to free the surface from contamination by metals, particles, and organic matter.

[0003] RCA cleaning is a "standard process" for removing organic matter, metals and alkaline ions from silicon wafers. RCA is the English abbreviation of the American Radio Corporation. Kern and Puotinen, who worked there, proposed SC-1 (Semiconductor Clean-1) and SC-2 (Semiconductor Clean-2) in the 1960s, which laid the foundation for modern semiconductor cleaning technology. They are standard cleaning solutions No. 1 and No. 2, and some people call them APM (ammonia and hydrogen peroxide) and HPM (hydrochloric acid and hydrogen peroxide).

[0004] In the related art, the HPM standard solution used in the SC-2 cleaning process has a formula of HCl:H2O2:H2O=1:1:6~1:2:8. When the HPM standard solution is used to clean the wafer, a large amount of particles are easily deposited on the wafer surface. Summary of the invention

[0005] According to one aspect of the present application, a wafer cleaning solution is provided for use in an SC-2 cleaning process, wherein the cleaning solution comprises hydrochloric acid, hydrogen peroxide and deionized water; wherein the pH value of the cleaning solution is greater than 2.

[0006] In some embodiments of the present application, the pH value of the cleaning solution is greater than or equal to 2.5.

[0007] In some embodiments of the present application, the volume ratio of the hydrochloric acid, the hydrogen peroxide and the deionized water is 1:1:900 to 1:6:843.

[0008] In some embodiments of the present application, the mass ratio of the hydrochloric acid, the hydrogen peroxide and the deionized water is 0.06:0.3:99.64 to 0.06:0.05:99.89.

[0009] In some embodiments of the present application, the applicable temperature of the cleaning solution is 20°C to 30°C.

[0010] In some embodiments of the present application, the applicable temperature of the cleaning solution is 25°C.

[0011] In some embodiments of the present application, the cleaning solution is used to remove at least one of the following metal elements:

[0012] Al, Cu, Mn, Sr, Ba, Fe, Mo, Ti, Ca, K, Na, V, Co, Li, Ni, W, Cr, Mg, Pb, Zn.

[0013] In some embodiments of the present application, the cleaning solution is used to make the surface of the wafer present a network-like negative charge distribution when cleaning the wafer.

[0014] In some embodiments of the present application, the cleaning liquid is applied to a wafer tank cleaning machine.

[0015] According to another aspect of the present application, a wafer cleaning method is provided, the cleaning method comprising:

[0016] Making the wafer contact with any one of the cleaning solutions described above and cleaning it for a preset time;

[0017] The cleaned wafer is dried.

[0018] The wafer cleaning liquid and cleaning method of the present application can effectively prevent particles from being deposited on the wafer surface, thereby reducing the amount of particles deposited on the wafer surface and improving the cleaning effect on the wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] By describing the embodiments of the present application in more detail in conjunction with the accompanying drawings, the above and other purposes, features and advantages of the present application will become more apparent. The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings, the same reference numerals generally represent the same components or steps.

[0020] Figure 1 The figure shows the increase or decrease of the particles deposited on the wafer surface after the wafer is cleaned using the HPM solution in the related art and the wafer cleaning solution of the present application.

[0021] Figure 2 The figure shows the distribution diagram of the median of LLS026 particles deposited on the surface of the wafer after the wafer is cleaned using the HPM solution in the related art and the wafer cleaning solution of the present application.

[0022] Figure 3 The figure shows the median dispersion of LLS026 particles deposited on the wafer surface after the wafer is cleaned using the HPM solution in the related art and the wafer cleaning solution of the present application.

[0023] Figure 4It shows that after the HPM solution in the related art and the wafer cleaning solution of the present application are used to clean the wafer in the FP 1 cleaning equipment, the median number of LLS026 particles deposited on the wafer surface is equal to or lower than Figure 2 The yield at the second baseline in .

[0024] Figure 5 It shows that after the wafer is cleaned in the FP 2 cleaning equipment using the HPM solution in the related art and the wafer cleaning solution of the present application, the median number of LLS026 particles deposited on the wafer surface is equal to or lower than Figure 2 The yield at the second baseline in .

[0025] Figure 6 The figure shows the median distribution of LLS037 and LLS055 particles deposited on the surface of the wafer after the wafer is cleaned using the HPM solution in the related art and the wafer cleaning solution of the present application.

[0026] Figure 7 The figure shows the degree of dispersion of the median of LLS037 and LLS055 particles deposited on the surface of the wafer after the wafer is cleaned using the HPM solution in the related art and the wafer cleaning solution of the present application.

[0027] Figure 8 It shows that after the HPM solution in the related art and the wafer cleaning solution of the present application are used to clean the wafer in the FP 1 cleaning equipment, the median number of LLS037 and LLS055 particles deposited on the wafer surface is equal to or lower than Figure 6 The yield at the second baseline in .

[0028] Fig. 9 It shows that after the wafer is cleaned in the FP 2 cleaning equipment using the HPM solution in the related art and the wafer cleaning solution of the present application, the median number of LLS037 and LLS055 particles deposited on the wafer surface is equal to or lower than Figure 6 The yield at the second baseline in .

[0029] Fig.10 A comparison chart of the metal element content on the wafer surface after the wafer is cleaned using the HPM solution in the related art and the wafer cleaning solution of the present application is shown.

[0030] Fig.11 It shows that after the wafer is cleaned using the HPM solution in the related art and the wafer cleaning solution of the present application, the Al element on the wafer surface changes with the cleaning time. DETAILED DESCRIPTION

[0031] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present application. However, it is apparent to those skilled in the art that the present application can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present application, some technical features well known in the art are not described.

[0032] It should be understood that the present application can be implemented in different forms and should not be construed as being limited to the embodiments presented herein. On the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present application to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.

[0033] In some related technologies, the HPM standard solution used in the SC-2 cleaning process has a formula of HCl:H2O2:H2O=1:1:6~1:2:8. The pH value of the HPM standard solution is less than 2, and the applicable temperature is 65℃~80℃. In the process of using the HPM standard solution to clean the wafer, because the pH value of the HPM standard solution is less than 2, the surface of the wafer presents a network of positive charge distribution. Given that particles generally have negative charge properties, based on the principle of opposite charges attracting each other, it is easy to cause particles to deposit on the surface of the wafer.

[0034] In addition, as the cleaning time continues to increase, the content of metal elements on the wafer surface, such as aluminum, copper and other metal types, shows a gradual upward trend.

[0035] In other related technologies, the volume ratio of the HPM solution used in the SC-2 cleaning process is: HCl:H2O2:H2O=1:1:140, and the pH value is less than 2. Similarly, in the process of using the HPM standard solution to clean the wafer, because the pH value of the HPM standard solution is less than 2, the wafer surface presents a network of positive charge distribution. Given that particles generally have negative charge properties, based on the principle of opposite charges attracting each other, it is easy to cause particles to deposit on the wafer surface.

[0036] Moreover, as the cleaning time continues to increase, the content of metal elements on the wafer surface, such as aluminum, copper and other metal types, shows a gradual upward trend.

[0037] In order to solve at least one of the above problems, the present application provides a wafer cleaning solution for use in an SC-2 cleaning process, wherein the cleaning solution comprises hydrochloric acid, hydrogen peroxide and deionized water; wherein the pH value of the cleaning solution is greater than 2.

[0038] The wafer cleaning liquid according to the present application can effectively prevent particles from being deposited on the wafer surface, thereby reducing the amount of particles deposited on the wafer surface and improving the cleaning effect on the wafer.

[0039] In addition, the cleaning solution of the present application can also properly solve the problem of the gradual increase in the metal element content on the wafer surface due to the extension of the cleaning time.

[0040] In order to thoroughly understand the present application, detailed steps and structures will be presented in the following description to illustrate the technical solution proposed by the present application. The preferred embodiments of the present application are described in detail below, but in addition to these detailed descriptions, the present application may also have other implementation methods.

[0041] According to one aspect of the present application, a cleaning solution for wafers is provided. The cleaning solution is used in an SC-2 cleaning process and includes hydrochloric acid (HCl), hydrogen peroxide (H2O2) and deionized water (DIW); wherein the pH value of the cleaning solution is greater than 2.

[0042] The cleaning solution of this embodiment is an acidic solution of H2O2 and HCl, which has extremely strong oxidizing and complexing properties. The chloride ions contained in HCl can react with metal ions to form complexes that are easily dissolved in deionized water. These complexes can be effectively removed by washing with deionized water. H2O2 can promote the conversion of metal ions into soluble salts by its oxidizing effect, which can also be removed by washing with deionized water. In this way, metal ion contaminants attached to the surface of the wafer can be efficiently removed.

[0043] It should be emphasized that, in the process of using the cleaning solution of this embodiment to clean the wafer, because the pH value of the cleaning solution is greater than 2, the surface of the wafer can be caused to present a network of negative charge distribution. In addition, particles also carry negative charges under normal conditions, so according to the principle that like charges repel each other, it can effectively prevent particles from depositing on the surface of the wafer, thereby reducing the number of particles deposited on the surface of the wafer and improving the cleaning effect of the wafer.

[0044] In addition, the cleaning solution of this embodiment can also properly solve the problem of the gradual increase of the metal element content on the wafer surface due to the extension of the cleaning time.

[0045] In some embodiments, the pH value of the cleaning solution is greater than or equal to 2.5.

[0046] Specifically, in the process of using a cleaning solution to clean a wafer, given that the charge state on the wafer surface is related to the pH value of the cleaning solution, in order to maximize the guarantee that the wafer surface can present a network of negative charge distribution, the pH value of the cleaning solution can be further appropriately increased under the premise that the pH value of the cleaning solution is greater than 2. For example, the pH value of the cleaning solution can be set to any appropriate value such as 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, etc., and this is not limited.

[0047] In some embodiments, the pH value of the cleaning solution can be made greater than 2, or greater than or equal to 2.5 by changing the ratio of HCl, H2O2 and deionized water in the cleaning solution.

[0048] Specifically, H2O2 in the cleaning solution is a weak acid with extremely weak acidity, and its pH value in water is usually close to neutral, that is, the pH value is about 7. HCl is a strong acid with a pH value much lower than 7, for example, the pH value of 0.001M (mol / L) HCl is about 3, and the pH value of 0.01M (mol / L) HCl is about 2.

[0049] Take the commonly used 37% hydrochloric acid solution as an example, its density is P, the molar mass of HCl is M, substitute it into the formula:

[0050] Mol=W%×P / M

[0051] From the above formula, we can deduce how many Mol of HCL is contained in 1 liter of 37% hydrochloric acid solution.

[0052] On the basis of ensuring that the pH value of the cleaning solution is greater than 2, the volume calculation formula of the required 37% concentration hydrochloric acid solution is as follows:

[0053] The volume of 37% hydrochloric acid solution (mL) = the volume of cleaning solution (L) × 0.01 mol / L ÷ Mol / L.

[0054] Taking the volume of the wafer cleaning solution that needs to be configured (usually measured in liters) as an example, substituting the volume of the wafer cleaning solution into the above formula can determine the volume of 37% hydrochloric acid solution required to ensure that the pH value of the configured cleaning solution is greater than 2.

[0055] In one example, the volume ratio of the hydrochloric acid, the hydrogen peroxide, and the deionized water is 1:1:900 to 1:6:843.

[0056] Compared with the HPM standard solution with a formula of HCl:H2O2:H2O=1:1:6~1:2:8 adopted in the related art, or the HPM solution with a volume ratio of HCl:H2O2:H2O=1:1:140, the formula of this embodiment not only reduces the amount of particle deposition on the wafer surface and reduces the metal element content on the wafer surface, but also reduces the amount of HCl used, and has a higher cost-effectiveness.

[0057] In one example, the mass ratio of the hydrochloric acid, the hydrogen peroxide, and the deionized water is 0.06:0.3:99.64 to 0.06:0.05:99.89.

[0058] In some embodiments, the applicable temperature of the cleaning solution is 20°C to 30°C, for example, 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, etc., without limitation.

[0059] Specifically, the cleaning solution of this embodiment is not suitable for the applicable temperature range of 65℃~80℃ of the HPM standard solution in the related art. The main reason is that although the increase in temperature can significantly accelerate the dissolution and oxidation process of organic matter on the wafer surface and reduce the metal content on the wafer surface, the increase in temperature will also greatly accelerate the decomposition rate of H2O2, thereby increasing the concentration of HCl in the cleaning solution, and ultimately leading to an unstable pH value of the cleaning solution. After comprehensive consideration, the applicable temperature of the cleaning solution of this embodiment is selected to be room temperature, preferably 25℃.

[0060] In some embodiments, the cleaning solution of the wafer can remove one or more metal elements on the surface of the wafer. The metal elements may include Al, Cu, Mn, Sr, Ba, Fe, Mo, Ti, Ca, K, Na, V, Co, Li, Ni, W, Cr, Mg, Pb, Zn, etc., without limitation.

[0061] In some embodiments, the wafer cleaning liquid may be applied to a wafer tank cleaning machine or any other suitable wet cleaning equipment, without limitation.

[0062] Embodiment 2

[0063] According to another aspect of the present application, a method for cleaning a wafer is provided. The cleaning method comprises the following steps:

[0064] Step S21, contacting the wafer with a cleaning solution and performing cleaning for a preset time;

[0065] Step S22, drying the cleaned wafer.

[0066] Among them, the wafer cleaning liquid can be implemented as the wafer cleaning liquid mentioned above, and reference can be made to the introduction above, which will not be repeated here.

[0067] Specifically, the wafer can be placed in a cleaning device (such as a wafer tank cleaning machine or any other suitable wet cleaning device), in which the wafer is fully contacted with the cleaning solution and cleaned for a preset time, wherein the preset time can be set according to the actual cleaning situation and is not limited thereto. The cleaning solution includes hydrochloric acid, hydrogen peroxide and deionized water, which is an acidic solution of H2O2 and HCl, and has extremely strong oxidizing and complexing properties, wherein the chloride ions contained in HCl can react with metal ions to form complexes that are easily dissolved in deionized water, and these complexes can be effectively removed with deionized water rinsing; H2O2 can promote the conversion of metal ions into soluble salts by virtue of its oxidizing effect, and can also be removed by deionized water rinsing. In this way, metal ion contaminants attached to the surface of the wafer can be efficiently removed.

[0068] After cleaning, the wafer can be dried by any suitable method such as spin drying, IPA drying, Marangoni drying, Rotagoni drying, etc., thereby completing the entire cleaning operation of the wafer.

[0069] It should be emphasized that the pH value of the cleaning solution used is greater than 2. During the cleaning process of the wafer, the cleaning solution with a pH value greater than 2 can cause the wafer surface to present a network of negative charge distribution. In addition, particles also carry negative charges under normal conditions, so according to the principle that like charges repel each other, it can effectively prevent particles from depositing on the wafer surface, thereby reducing the number of particles deposited on the wafer surface and improving the cleaning effect of the wafer.

[0070] In addition, by making the pH value of the cleaning solution greater than 2, the problem of the gradual increase in the metal element content on the wafer surface due to the extension of the cleaning time can be properly solved.

[0071] Exemplarily, the pH value of the cleaning solution is greater than or equal to 2.5.

[0072] Exemplarily, the volume ratio of hydrochloric acid, hydrogen peroxide and deionized water is 1:1:900 to 1:6:843.

[0073] Exemplarily, the mass ratio of hydrochloric acid, hydrogen peroxide and deionized water is 0.06:0.3:99.64 to 0.06:0.05:99.89.

[0074] Exemplarily, the applicable temperature of the cleaning liquid is 20°C to 30°C.

[0075] Exemplarily, the applicable temperature of the cleaning solution is 25°C.

[0076] Exemplarily, the cleaning liquid is used to remove at least one of the following metal elements:

[0077] Al, Cu, Mn, Sr, Ba, Fe, Mo, Ti, Ca, K, Na, V, Co, Li, Ni, W, Cr, Mg, Pb, Zn.

[0078] Embodiment 3

[0079] This embodiment verifies the amount of particles deposited on the wafer surface after the wafer is cleaned using the HPM solution in the related art and the wafer cleaning solution of the present application. The volume ratio of the HPM solution in the related art is HCl:H2O2:H2O=1:1:140; the volume ratio of the wafer cleaning solution of the present application is HCl:H2O2:H2O=1:1:900-1:6:843.

[0080] In addition, in order to exclude the influence of other conditions on the amount of particle deposition on the wafer surface (only verifying the influence of pH value on the amount of particle deposition on the wafer surface), the same conditions are used for the HPM solution in the related art and the wafer cleaning solution of the present application. For example, the applicable temperature of both is 25°C.

[0081] Specifically, several groups of wafers are first prepared, and then some of the wafers are cleaned using the HPM solution in the related art in a cleaning device, and other wafers are cleaned using the wafer cleaning solution of the present application in a cleaning device, and after the cleaning is completed, the median of the particles deposited on the surface of the wafer is tested to obtain Figure 2 .

[0082] For example, Figure 2 As shown, the ordinate in the figure represents the median distribution of the deposited particles after the wafer is cleaned. It can be seen that after the wafer is cleaned using the HPM solution in the related art, the median of the LL026 particles deposited on the wafer surface is higher than that of the wafer using the cleaning solution of the present application;

[0083] like Figure 6 As shown in the figure, the vertical axis represents the median distribution of deposited particles after the wafer is cleaned. It can be seen that after the wafer is cleaned with the HPM solution in the related technology, the median of LL037 particles deposited on the wafer surface is higher than that of the wafer using the cleaning solution of the present application; after the wafer is cleaned with the HPM solution in the related technology, the median of LL055 particles deposited on the wafer surface is higher than that of the wafer using the cleaning solution of the present application.

[0084] It can be clearly seen that compared with the HPM solution in the related art, the wafer cleaning solution of the present application can more effectively prevent particles from depositing on the wafer surface, thereby reducing the amount of particle deposition on the wafer surface and having a better cleaning effect on the wafer.

[0085] Embodiment 4

[0086] This embodiment further verifies the amount of particles deposited on the wafer surface after the wafer is cleaned using the HPM solution in the related art and the wafer cleaning solution of the present application. The volume ratio of the HPM solution in the related art is HCl:H2O2:H2O=1:1:140; the volume ratio of the wafer cleaning solution of the present application is HCl:H2O2:H2O=1:1:900-1:6:843.

[0087] Similarly, in order to exclude the influence of other conditions on the amount of particle deposition on the wafer surface, the same conditions are used for the HPM solution in the related art and the wafer cleaning solution of the present application. Exemplarily, the applicable temperature of both is 25°C.

[0088] Specifically, several groups of wafers whose surface particle deposition amount has been measured are prepared, some of which are cleaned using the HPM solution in the related art, and other wafers are cleaned using the wafer cleaning liquid crystal circle of the present application, and then the increase or decrease in the number of particles deposited on the wafer surface is tested.

[0089] For example, Figure 1 As shown in the figure, the ordinate represents the increase or decrease in the number of deposited particles after the wafer is cleaned. The dotted line in the figure can be called the first baseline. It can be seen that after the HPM solution in the related art is used to clean the wafer, the number of LLS026 particles deposited on the wafer surface is significantly increased compared with the first baseline. After the wafer is cleaned using the cleaning solution of the present application, the number of LLS026 particles deposited on the wafer surface is significantly reduced compared with the first baseline. After the HPM solution in the related art is used to clean the wafer, the number of LLS026 particles deposited on the wafer surface is significantly reduced compared with the first baseline. The number of LLS037 particles deposited on the surface of the wafer increased significantly compared with the first baseline. After the wafer was cleaned with the wafer cleaning solution of the present application, the number of LLS037 particles deposited on the surface of the wafer decreased significantly compared with the first baseline. After the wafer was cleaned with the HPM solution in the related technology, the number of LLS055 particles deposited on the surface of the wafer increased significantly compared with the first baseline. After the wafer was cleaned with the wafer cleaning solution of the present application, the number of LLS055 particles deposited on the surface of the wafer decreased significantly compared with the first baseline.

[0090] It can be seen from this that compared with the HPM solution in the related art, the wafer cleaning solution of the present application can more effectively prevent particles from depositing on the wafer surface, thereby reducing the amount of particle deposition on the wafer surface and having a better cleaning effect on the wafer.

[0091] Embodiment 5

[0092] This embodiment further verifies the amount of particles deposited on the wafer surface after the wafer is cleaned using the HPM solution in the related art and the wafer cleaning solution of the present application. The volume ratio of the HPM solution in the related art is HCl:H2O2:H2O=1:1:140; the volume ratio of the wafer cleaning solution of the present application is HCl:H2O2:H2O=1:1:900-1:6:843.

[0093] Similarly, in order to exclude the influence of other conditions on the amount of particle deposition on the wafer surface, the same conditions are used for the HPM solution in the related art and the wafer cleaning solution of the present application. Exemplarily, the applicable temperature of both is 25°C.

[0094] Specifically, several groups of wafers are first prepared, and then some of the wafers are cleaned using the HPM solution in the related art in a cleaning device, and other wafers are cleaned using the wafer cleaning solution of the present application in a cleaning device, and after the cleaning is completed, the median dispersion of particles deposited on the surface of the wafer and the yield are tested;

[0095] like Figure 3 As shown, the ordinate in the figure represents the degree of dispersion of particles. Compared with the case where the HPM solution in the related art is used to clean the wafer in the FP 1 model cleaning equipment, after the wafer cleaning liquid of the present application is used to clean the wafer in the FP 1 model cleaning equipment, the curve in the figure is closer to the ordinate than the curve of the HPM solution in the related art, and the median of the LLS026 particles deposited on the wafer surface is more concentrated, as shown in FIG. Figure 2 and Figure 4 As shown, Figure 2 The dotted line in the figure can be called the second baseline. After the wafer is cleaned using the wafer cleaning solution of the present application in the FP 1 cleaning equipment, when the median of the LLS026 particles deposited on the wafer surface is equal to or lower than the second baseline, the yield is increased from 30% to 61%.

[0096] like Figure 7 As shown, the ordinate in the figure represents the degree of dispersion of the particles. Compared with the case where the HPM solution in the related art is used to clean the wafer in the FP 1 model cleaning equipment, after the wafer cleaning liquid of the present application is used to clean the wafer in the FP 1 model cleaning equipment, the curve in the figure is closer to the ordinate than the curve of the HPM solution using the related art, and the median of the LLS037 & LLS055 particles deposited on the wafer surface is more concentrated, as shown in FIG. Figure 6 and Figure 8 As shown, Figure 6The dotted line in the figure can also be called the second reference line. After the wafer cleaning liquid of the present application is used to clean the wafer in the FP 1 cleaning equipment, the yield rate is increased from 41.1% to 52.4% when the median number of LLS037 particles deposited on the wafer surface is equal to or lower than the second reference line. The yield rate is increased from 9.2% to 18.7% when the median number of LLS055 particles deposited on the wafer surface is equal to or lower than the second reference line.

[0097] like Figure 3 As shown, the ordinate in the figure represents the degree of dispersion of particles. Compared with the case where the HPM solution in the related art is used to clean the wafer in the FP 2 cleaning equipment, after the wafer cleaning solution of the present application is used to clean the wafer in the FP 2 cleaning equipment, the curve in the figure is closer to the ordinate than the curve of the HPM solution in the related art, and the median of the LLS026 particles deposited on the wafer surface is more concentrated, as shown in FIG. Figure 2 and Figure 5 As shown, after the wafer cleaning liquid of the present application is used to clean the wafer in the FP 2 cleaning equipment, the yield is increased from 53% to 78% when the median of the LLS026 particles deposited on the wafer surface is equal to or lower than the second baseline.

[0098] like Figure 7 As shown, the ordinate in the figure represents the degree of dispersion of the particles. Compared with the case where the HPM solution in the related art is used to clean the wafer in the FP 2 model cleaning equipment, after the wafer cleaning liquid of the present application is used to clean the wafer in the FP 2 model cleaning equipment, the curve in the figure is closer to the ordinate than the curve of the HPM solution using the related art, and the median of the LLS037 & LLS055 particles deposited on the wafer surface is more concentrated, as shown in FIG. Figure 6 and Fig. 9 As shown, after the wafer cleaning liquid of the present application is used to clean the wafer in the FP 2 cleaning equipment, the yield rate is increased from 42.4% to 81.5% when the median number of LLS037 particles deposited on the wafer surface is equal to or lower than the second baseline. The yield rate is increased from 13.4% to 40.1% when the median number of LLS055 particles deposited on the wafer surface is equal to or lower than the second baseline.

[0099] Embodiment 6

[0100] This embodiment verifies the influence of the HPM solution in the related art and the wafer cleaning solution of the present application on the metal element content on the wafer surface after the wafer is cleaned. The volume ratio of the HPM solution in the related art is HCl:H2O2:H2O=1:1:140; the volume ratio of the wafer cleaning solution of the present application is HCl:H2O2:H2O=1:1:900~1:6:843.

[0101] Similarly, in order to exclude the influence of other conditions on the amount of particle deposition on the wafer surface, the same conditions are used for the HPM solution in the related art and the wafer cleaning solution of the present application. Exemplarily, the applicable temperature of both is 25°C.

[0102] Specifically, several groups of wafers are first prepared, and then some wafers are cleaned using the HPM solution in the related technology in a cleaning device, and other wafers are cleaned using the wafer cleaning solution of the present application in a cleaning device, and after the cleaning is completed, the metal element content on the wafer surface is tested.

[0103] For example, Fig.10 As shown, the tested metal elements include Al, Cu, Mn, Sr, Ba, Fe, Mo, Ti, Ca, K, Na, V, Co, Li, Ni, W, Cr, Mg, Pb, Zn, etc. It can be seen that after the wafer is cleaned with the wafer cleaning solution of the present application, the content of the above metal elements on the wafer surface is reduced.

[0104] Take Al as an example, Fig.11 As shown in the figure, the ordinate represents the Al content on the wafer surface, and the abscissa represents the cleaning time. It can be seen that when the HPM solution in the related technology is used to clean the wafer, the Al content on the wafer surface gradually increases with the extension of the cleaning time; while when the HPM solution in the related technology is used to clean the wafer, the Al content on the wafer surface hardly increases with the extension of the cleaning time.

[0105] Embodiment 7

[0106] This embodiment verifies the effect of the amount of H2O2 on the amount of particle deposition on the wafer surface, based on the pH value of the wafer cleaning solution of the present application being greater than 2. Among them, the volume ratio of the HPM solution in the related art is HCl:H2O2:H2O=1:1:140, the volume ratio of the wafer cleaning solution of test 1 of the present application is HCl:H2O2:H2O=1:1:843~1:1:900, the volume ratio of the wafer cleaning solution of test 2 of the present application is HCl:H2O2:H2O=1:3:843~1:3:900, and the volume ratio of the wafer cleaning solution of test 3 of the present application is HCl:H2O2:H2O=1:6:843~1:6:900.

[0107] In addition, in order to exclude the influence of other conditions on the amount of particle deposition on the wafer surface (only verifying the influence of the amount of H2O2 on the amount of particle deposition on the wafer surface), the same conditions are used for the HPM solution in the related art, the cleaning solution of the wafer in Test 1 of this application, the cleaning solution of the wafer in Test 2 of this application, and the cleaning solution of the wafer in Test 3 of this application. Exemplarily, the applicable temperature of the four is 25°C.

[0108] Specifically, several groups of wafers are first prepared, and then some wafers are cleaned using the HPM solution in the related art in a cleaning device, and other wafers are cleaned using the wafer cleaning solution of the present application in a cleaning device. After the cleaning is completed, the yield of particles deposited on the surface of the wafer is tested, and the following Table 1 is obtained.

[0109] Table 1:

[0110]

[0111] In Table 1, after the wafers were cleaned using the HPM solution of the related art in the FP 1 cleaning equipment, the median number of LLS026 particles deposited on the wafer surface was equal to or lower than Figure 2 The second baseline is 30% yield and the median number of LLS037 particles is equal to or lower than Figure 6 The second baseline yield is 41% and the median number of LLS055 particles is equal to or lower than Figure 6 The yield rate is 9.2% when the second baseline is reached in the FP 1 cleaning equipment; after the wafer is cleaned using the cleaning solution of the wafer in the test 1 of the present application, the median number of LLS026 particles deposited on the surface of the wafer is equal to or lower than Figure 2 The second baseline yield is 61% and the median number of LLS037 particles is equal to or lower than Figure 6 The second baseline is 50% yield and the median number of LLS055 particles is equal to or lower than Figure 6The yield rate is 21% when the second baseline in the FP 1 cleaning equipment is used to clean the wafer using the cleaning solution of the wafer in the test 2 of this application. The median number of LLS026 particles deposited on the surface of the wafer is equal to or lower than Figure 2 The second baseline yield is 58% and the median number of LLS037 particles is equal to or lower than Figure 6 The second baseline yield is 52% and the median number of LLS055 particles is equal to or lower than Figure 6 The yield is 20% when the second baseline in the FP 1 cleaning equipment is used to clean the wafer using the cleaning solution of the wafer in the test 3 of this application. The median number of LLS026 particles deposited on the surface of the wafer is equal to or lower than Figure 2 The second baseline yield is 60% and the median number of LLS037 particles is equal to or lower than Figure 6 The second baseline yield is 52% and the median number of LLS055 particles is equal to or lower than Figure 6 The second baseline is 19% yield.

[0112] After the wafers were cleaned using the HPM solution of the related art in the FP 2 cleaning equipment, the median number of LLS026 particles deposited on the wafer surface was equal to or lower than Figure 2 The second baseline yield is 53% and the median number of LLS037 particles is equal to or lower than Figure 6 The second baseline yield is 42% and the median number of LLS055 particles is equal to or lower than Figure 6 The yield rate is 13.4% when the second baseline is used in the FP 1 cleaning equipment; after the wafer is cleaned using the cleaning solution of the wafer in the test 1 of this application, the median number of LLS026 particles deposited on the surface of the wafer is equal to or lower than Figure 2 The second baseline yield is 80% and the median number of LLS037 particles is equal to or lower than Figure 6 The second baseline yield is 80% and the median number of LLS055 particles is equal to or lower than Figure 6 The yield is 40% when the second baseline is reached; after the wafer is cleaned using the cleaning solution of the wafer in Test 2 of this application in the cleaning equipment of FP 1, the median number of LLS026 particles deposited on the surface of the wafer is equal to or lower than Figure 2 The second baseline yield is 77% and the median number of LLS037 particles is equal to or lower than Figure 6 The second baseline yield is 83% and the median number of LLS055 particles is equal to or lower than Figure 6The yield rate is 39% when the second baseline in the FP 1 cleaning equipment is used to clean the wafer using the cleaning solution of the wafer in the test 3 of this application. The median number of LLS026 particles deposited on the surface of the wafer is equal to or lower than Figure 2 The second baseline yield is 78% and the median number of LLS037 particles is equal to or lower than Figure 6 The second baseline yield is 81.5%, and the median number of LLS055 particles is equal to or lower than Figure 6 The yield at the second baseline is 40.1%.

[0113] It can be clearly seen that compared with the HPM solution with a pH value less than 2 in the related art, the wafer cleaning solution with a pH value greater than 2 in the present application can more effectively prevent particles from depositing on the wafer surface, thereby reducing the amount of particle deposition on the wafer surface and having a better cleaning effect on the wafer.

[0114] In addition, for the wafer cleaning solution of the present application, the amount of H2O2 used has almost no effect on the median number of particles deposited on the wafer surface, provided that the pH value is greater than 2. However, considering the volatility of H2O2, a low concentration of H2O2 will lead to an unstable pH value of the cleaning solution, so in general, a volume ratio of HCl:H2O2:H2O=~1:1:900~1:6:843 is used.

[0115] Based on the above description, the wafer cleaning liquid and cleaning method according to the embodiments of the present application can effectively prevent particles from depositing on the wafer surface, thereby reducing the amount of particles deposited on the wafer surface and improving the cleaning effect on the wafer.

[0116] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely exemplary and are not intended to limit the scope of the present application to this. Those of ordinary skill in the art may make various changes and modifications therein without departing from the scope and spirit of the present application. All these changes and modifications are intended to be included within the scope of the present application as required by the appended claims.

[0117] Similarly, it should be understood that in order to streamline the present application and help understand one or more of the various application aspects, in the description of the exemplary embodiments of the present application, the various features of the present application are sometimes grouped together into a single embodiment, figure, or description thereof. However, the method of the present application should not be interpreted as reflecting the following intention: the claimed application requires more features than the features clearly stated in each claim. More specifically, as reflected in the corresponding claims, the application point is that the corresponding technical problem can be solved with less than all the features of a single disclosed embodiment. Therefore, the claims following the specific embodiment are hereby explicitly incorporated into the specific embodiment, wherein each claim itself serves as a separate embodiment of the present application.

[0118] In addition, those skilled in the art will appreciate that, although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the claims, any one of the claimed embodiments can be used in any combination.

[0119] It should be noted that the above embodiments illustrate rather than limit the present application, and that those skilled in the art may devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference symbol between brackets should not be construed as a limitation to the claims. The use of the words first, second, and third, etc. does not indicate any order. These words may be interpreted as names.

Claims

1. A wafer cleaning solution, characterized in that: Used in the SC-2 cleaning process, the cleaning solution includes hydrochloric acid, hydrogen peroxide and deionized water; wherein the pH value of the cleaning solution is greater than 2.

2. The cleaning solution according to claim 1, characterized in that The pH value of the cleaning solution is greater than or equal to 2.

5.

3. The cleaning solution according to claim 1, characterized in that The volume ratio of the hydrochloric acid, the hydrogen peroxide and the deionized water is 1:1:900 to 1:6:

843.

4. The cleaning solution according to claim 1, characterized in that The mass ratio of the hydrochloric acid, the hydrogen peroxide and the deionized water is 0.06:0.3:99.64 to 0.06:0.05:99.

89.

5. The cleaning solution according to claim 1, characterized in that The applicable temperature of the cleaning solution is 20°C to 30°C.

6. The cleaning solution according to claim 5, characterized in that The applicable temperature of the cleaning solution is 25°C.

7. The cleaning solution according to claim 1, characterized in that The cleaning liquid is used to remove at least one of the following metal elements: Al, Cu, Mn, Sr, Ba, Fe, Mo, Ti, Ca, K, Na, V, Co, Li, Ni, W, Cr, Mg, Pb, Zn.

8. The cleaning solution according to claim 1, characterized in that The cleaning liquid is used to make the surface of the wafer present a net-like negative charge distribution when cleaning the wafer.

9. The cleaning solution according to claim 1, characterized in that The cleaning liquid is applied to a wafer tank cleaning machine.

10. A method for cleaning a wafer, characterized in that: The cleaning method comprises: Contacting the wafer with the cleaning solution as described in any one of claims 1 to 9, and performing cleaning for a preset time; The cleaned wafer is dried.

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