Wafer cleaning method and wafer

Abstract

The invention provides a cleaning method for a wafer and the wafer. The cleaning method comprises the following steps: supplying HF-containing cleaning liquid to a wafer to be cleaned so as to execute etching rotary cleaning; a cleaning solution containing O3 is supplied to the wafer to be cleaned so as to execute oxidation rotation cleaning; sequentially and alternately executing etching rotary cleaning and oxidation rotary cleaning for multiple times; wherein the duration time of the etching rotary cleaning executed for the first time is longer than the duration time of the subsequent etching rotary cleaning, and the duration time of the oxidation rotary cleaning executed for the last time is longer than the duration time of the previous oxidation rotary cleaning.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of semiconductor manufacturing, and in particular, to a cleaning method for a wafer and a wafer. BACKGROUND

[0002] As a core material for manufacturing integrated circuits, the surface quality of a wafer directly affects the performance and reliability of semiconductor devices. With the rapid development of semiconductor technology, the requirement for the particle content on the surface of a wafer is becoming increasingly stringent. This is mainly because the presence of particles on the surface of a wafer not only reduces the performance of semiconductor devices, but also can cause device failure. Therefore, the cleaning process of a wafer is a key step in the semiconductor manufacturing process.

[0003] The cleaning process of a wafer is mainly to remove particles and metal ions on the surface of a wafer. This is mainly because particles and metal ions on the surface of a wafer will have a negative impact on the performance of semiconductor devices, especially the metal ion tin (Sn) which will form intermetallic compounds on the surface of a wafer. These intermetallic compounds will change the microstructure and chemical composition of the surface of a wafer, which will affect the performance of the wafer. However, the commonly used cleaning method, such as RCA cleaning method, may increase the particle content on the surface of a wafer and the number of metal ions after cleaning the wafer with SC2 solution in some examples.

[0004] In summary, it is important to provide a cleaning method for a wafer to reduce the particle content on the surface of a wafer and the number of metal ions, and to improve the cleanliness of the surface of a wafer, which is crucial for improving the performance and reliability of semiconductor devices. SUMMARY

[0005] The present disclosure provides a cleaning method for a wafer and a wafer; can solve the problem of too high particle content and metal ion number on the surface of a wafer in the related art, and improve the cleanliness of the surface of a wafer.

[0006] The technical solution of the present disclosure is implemented as follows: In a first aspect, the present disclosure provides a cleaning method for a wafer, the cleaning method comprising: supplying a cleaning liquid containing HF to a wafer to be cleaned to perform etching spin cleaning; supplying a cleaning liquid containing O3 to the wafer to be cleaned to perform oxidation spin cleaning; and alternately performing the etching spin cleaning and the oxidation spin cleaning in sequence for multiple times; wherein the duration of the first performed etching spin cleaning is longer than the duration of each subsequent etching spin cleaning, and the duration of the last performed oxidation spin cleaning is longer than the duration of each previous oxidation spin cleaning.

[0007] In some possible implementations, the first performed etching spin cleaning completely etches the oxide layer of the wafer surface to be cleaned.

[0008] In some possible implementations, the duration of the first performed etching spin cleaning is greater than or equal to 20 seconds and less than or equal to 30 seconds; and the duration of each subsequent etching spin cleaning is greater than or equal to 4 seconds and less than or equal to 10 seconds.

[0009] In some possible implementations, the duration of the last performed oxidation spin cleaning is greater than or equal to 15 seconds and less than or equal to 30 seconds; and the duration of each previous oxidation spin cleaning is greater than or equal to 5 seconds and less than or equal to 10 seconds.

[0010] In some possible implementations, during the first spin cleaning, after the last performed oxidation spin cleaning, the method further comprises: supplying the deionized water to the wafer to be cleaned for a second spin rinse with a cleaning time greater than or equal to 5 seconds and less than or equal to 10 seconds.

[0011] In some possible implementations, during the first spin cleaning, in the cleaning solution containing HF, the mass concentration of the HF is greater than or equal to 0.3 wt% and less than or equal to 1.1 wt%.

[0012] In some possible implementations, in the cleaning solution containing O3, the volume concentration of the O3 is greater than or equal to 25 ppm and less than or equal to 30 ppm.

[0013] In some possible implementations, the flow rate of the cleaning solution is greater than or equal to 0.9 L / min and less than or equal to 1.4 L / min.

[0014] In some possible implementations, the number of times of alternately performing the etching spin cleaning and the oxidation spin cleaning is greater than or equal to 3 times and less than or equal to 6 times.

[0015] In some possible implementations, between the etching spin cleaning and the oxidation spin cleaning, the method further comprises: supplying the deionized water to the wafer to be cleaned to perform a first spin rinse.

[0016] In a second aspect, the disclosure provides a wafer, after being cleaned according to the cleaning method for a wafer of the first aspect, the content of particles with a size of less than or equal to 19 nm on the surface of the wafer is greater than or equal to 0 ea and less than or equal to 12 ea, the number of protrusion defects on the surface of the wafer is greater than or equal to 0 ea and less than or equal to 6 ea, and the number of metal ions Sn on the surface of the wafer is less than or equal to 1.0×10 7 atom / cm 2 .

[0017] In some possible implementations, the content of particles with a size of less than or equal to 19 nm on the surface of the wafer is greater than or equal to 0 ea and less than or equal to 10 ea, the number of protrusion defects on the surface of the wafer is greater than or equal to 0 ea and less than or equal to 4 ea, and the number of metal ions Sn on the surface of the wafer is less than or equal to 6×10 6 atom / cm 2 .

[0018] The disclosure provides a cleaning method for a wafer and a wafer; a cleaning liquid containing HF is supplied to the wafer to be cleaned to perform etching spin cleaning; a cleaning liquid containing O3 is supplied to the wafer to be cleaned to perform oxidation spin cleaning; and the etching spin cleaning and the oxidation spin cleaning are alternately performed for multiple times; wherein the duration of the first performed etching spin cleaning is longer than the duration of each subsequent etching spin cleaning, and the duration of the last performed oxidation spin cleaning is longer than the duration of each previous oxidation spin cleaning. By prolonging the duration of the first etching spin cleaning, the oxide layer on the surface of the wafer is completely removed, and then some small defects on the surface of the wafer are removed, and the level of metal ions is reduced; the duration of the last oxidation spin cleaning can achieve the effect of re-oxidation, and can cover smaller defects. Alternately performing the etching spin cleaning and the oxidation spin cleaning for multiple times can improve the particle level and the metal level on the surface of the wafer. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 A flowchart of a cleaning method for a wafer is provided for the disclosure.

[0020] Figure 2 A schematic diagram of the distribution of the content of particles on the surface of a wafer after the wafer is cleaned by using a cleaning liquid containing HF and a cleaning liquid containing O3 is provided for the disclosure.

[0021] Figure 3 A schematic diagram of the distribution of the content of particles on the surface of a wafer after the wafer is cleaned by using a cleaning liquid containing HF and a cleaning liquid containing O3 in the related art is provided.

[0022] Figure 4A Jut defect distribution diagram of a wafer surface after the wafer is cleaned by a cleaning solution containing HF and a cleaning solution containing O3.

[0023] Figure 5 A Jut defect distribution diagram of a wafer surface after the wafer is cleaned by a cleaning solution containing HF and a cleaning solution containing O3. DETAILED DESCRIPTION

[0024] The technical solutions in the present disclosure will be described clearly and completely below in combination with the drawings in the present disclosure.

[0025] As mentioned above, in the semiconductor manufacturing process, the particle content and the number of metal ions on the surface of the wafer have a direct impact on the performance of the semiconductor device. In particular, the metal ion Sn will diffuse and chemically react with Si or other metal ions when the wafer surface is in contact with them, forming intermetallic compounds. The formation of these intermetallic compounds will change the microstructure and chemical composition of the wafer surface, and have an important impact on the performance of the wafer and its semiconductor device.

[0026] In the related art, during the process of treating the metal ion Sn on the surface of the wafer, the surface roughness of the wafer will increase due to improper process control. Understandably, a reasonable process after cleaning the particles and metal ion Sn on the surface of the wafer improves the flatness of the wafer surface, which is conducive to subsequent processes such as photolithography and etching, and improves the manufacturing precision of the semiconductor device. However, if the surface roughness of the wafer is too large, it may, for example, cause the adhesion of the metal film to decrease, the resolution of the photolithographic pattern to decrease, and so on.

[0027] Currently, the cleaning method for wafers includes a tank immersion cleaning method and a single wafer spin cleaning method. The tank immersion cleaning method is a method for batch cleaning wafers. Specifically, multiple wafers are placed in a wafer basket for carrying wafers, and then the wafer basket is sequentially immersed in cleaning tanks containing different cleaning solutions by a robot for cleaning. This tank immersion cleaning method can clean multiple wafers at the same time, but this cleaning method can cause particles and metal ions on one wafer to be transferred to another wafer, thereby affecting the final cleaning effect. The single wafer spin cleaning method is to place the wafer on a rotating carrier and clean the wafer by spraying cleaning solution on the wafer. This single wafer spin cleaning method can only clean one wafer at a time, so the cleanliness of the cleaned wafer is higher.

[0028] However, the inventors found that when using the single-wafer spin cleaning method to clean the wafer, if the concentration of the cleaning solution containing HF and the cleaning solution containing O3 and the cleaning time are not reasonably controlled, the particle content and the number of metal ions Sn on the surface of the wafer can still be high. Based on this, in the present disclosure, it is expected to reduce the particle content and the number of metal ions on the surface of the wafer by controlling the duration of etching spin cleaning with the cleaning solution containing HF and the action time of the cleaning solution containing O3 on the surface of the wafer, and to improve the cleanliness of the surface of the wafer. For details, see Figure 1 which shows a cleaning method for a wafer provided by the present disclosure, which specifically comprises the following steps: In step S110, a cleaning solution containing HF is supplied to the wafer to be cleaned to perform etching spin cleaning; In step S120, a cleaning solution containing O3 is supplied to the wafer to be cleaned to perform oxidation spin cleaning; In step S130, etching spin cleaning and oxidation spin cleaning are alternately performed multiple times in sequence.

[0029] In which the duration of the first etching spin cleaning is longer than the duration of each subsequent etching spin cleaning, and the duration of the last oxidation spin cleaning is longer than the duration of each previous oxidation spin cleaning.

[0030] In some examples, the wafer to be cleaned in the present disclosure is spin cleaned in a single-finish clean system (S-FCS).

[0031] It can be understood that in the process of cleaning the wafer, the cleaning solution containing HF is mainly used for etching the surface of the wafer to remove the particles and metal ions Sn on the surface of the wafer. As for the cleaning solution containing O3, on the one hand, it is used to oxidize the intermetallic compounds on the surface of the wafer to change its chemical properties so that it is easier to dissolve or be removed; on the other hand, O3 will decompose in water to produce hydroxyl radicals with strong oxidizing properties. These hydroxyl radicals can accelerate the chemical reaction in the cleaning process to rapidly react with organic contaminants and inorganic impurities on the surface of the wafer, thereby improving the surface quality of the wafer.

[0032] The technical solution of the present disclosure first etches the rotating cleaning time to be greater than the duration of subsequent rotating cleaning. Through the first long duration etching rotating cleaning, the initial oxide layer on the wafer surface and the deeply embedded particle contaminants (such as metal ions and organic residues) are sufficiently removed, laying a clean substrate for subsequent cycles, preventing excessive etching that leads to increased surface roughness, while maintaining the efficiency of layer-by-layer stripping of contaminants. By extending the O3 treatment time to generate a dense oxide layer, the micro-damage caused by the previous etching can be repaired, a passivation layer is formed, and the risk of recontamination in subsequent processes is reduced.

[0033] For Figure 1 In some possible implementations of the technical solution shown in the figure, the duration of the first performed etching rotating cleaning is longer than the duration of each subsequent etching rotating cleaning, which is used to completely etch the oxide layer on the wafer surface, and the duration of the last performed oxidation rotating cleaning is longer than the duration of each previous oxidation rotating cleaning.

[0034] For Figure 1 In some possible implementations of the technical solution shown in the figure, the duration of the first performed etching rotating cleaning is greater than or equal to 20 seconds and less than or equal to 30 seconds; the duration of each subsequent etching rotating cleaning is greater than or equal to 4 seconds and less than or equal to 10 seconds.

[0035] The duration of the last performed oxidation rotating cleaning is greater than or equal to 15 seconds and less than or equal to 30 seconds; the duration of each previous oxidation rotating cleaning is greater than or equal to 5 seconds and less than or equal to 10 seconds.

[0036] Specifically, referring to Figure 2 , the first performed etching rotating cleaning uses a longer duration (20-30 seconds) to completely remove the oxide layer 201 on the wafer surface and deep metal contaminants (such as Sn), effectively reducing the surface metal level to an excellent range, while eliminating defects left over from previous processes. During the first etching rotating cleaning process, the oxide layer 201 is completely stripped, and the surface micro-defects are etched, significantly improving the LLS (wafer surface particle count) level. Compared to the multiple etching rotating cleaning duration shown in Figure 3 , the multiple oxidation rotating cleaning scheme, and the technical solution in which the oxide layer on the wafer surface is not completely stripped during etching, can reduce the wafer surface micro-defects and significantly improve the LLS (wafer surface particle count) level.

[0037] Further, as shown in Figure 4As shown, the wafer can have Jut-type defects 202 inside before cleaning, and an oxide layer 201 can be formed on the surface due to previous processes or contact with air. If the first etching spin cleaning is too short, the oxide layer 201 can not be completely etched, or even if the oxide layer 201 is etched, the Jut-type defects 202 inside can not be effectively processed. This will result in the oxide layer generated in subsequent processes failing to cover the Jut-type defects 202. Referring to Figure 5 By prolonging the duration of the first etching spin cleaning (20-30 seconds), high-intensity etching is performed, which not only completely eliminates the oxide layer 201 on the surface of the wafer, but also etches and modifies the Jut-type defects 202, thereby reducing their size. In this way, the oxide layer generated subsequently can completely cover the Jut-type defects 202.

[0038] In some examples, the duration of each subsequent etching spin cleaning is shortened to 4-10 seconds, and a “light etching-light oxidation” cycle is formed by combining light oxidation (the duration of the oxidation spin cleaning is greater than or equal to 5 seconds and less than or equal to 10 seconds), which dynamically adjusts the thickness of the surface oxide layer, avoids the increase in surface roughness caused by excessive etching, and gradually optimizes the surface flatness through repeated oxidation-etching processes, further reducing the LLS and Haze levels. Finally, the duration of the last oxidation spin cleaning is prolonged (the duration is greater than or equal to 15 seconds and less than or equal to 40 seconds), and a uniform and dense oxide layer is formed by heavy oxidation to cover the tiny defects and stabilize the surface quality.

[0039] In the present disclosure, by accurately controlling the action time of the cleaning liquid containing HF on the surface of the wafer to be cleaned, it can be ensured that the particles and metal ions Sn on the surface of the wafer to be cleaned are sufficiently removed, and excessive etching of the surface of the wafer to be cleaned is avoided to leave Jut defects on the surface of the wafer to be cleaned, which further affects the roughness of the surface of the wafer after cleaning. Therefore, by controlling the action time of the cleaning liquid containing HF on the surface of the wafer to be cleaned, the flatness of the surface of the wafer after cleaning can also be maintained.

[0040] In some examples, the mass concentration of HF in the cleaning solution containing HF can be controlled in the range of 0.3wt% to 1.1wt%, which can ensure the cleaning effect on the wafer to be cleaned and the safety in the cleaning process. Specifically, in the present disclosure, the rotating cleaning method is to clean the epitaxial wafer to be cleaned by using the chemical action of the cleaning solution without the mechanical action such as the brushing of the cleaning brush, under the rotation of the epitaxial wafer to be cleaned. Therefore, if the mass concentration of HF in the cleaning solution containing HF is too low, the chemical action of the cleaning solution on the epitaxial wafer to be cleaned is not enough to achieve the etching effect and cannot remove the particles and metal ions Sn on the surface of the wafer. In the mass concentration range provided in the present disclosure, the cleaning solution containing HF can react with the oxide of silicon to generate soluble fluoride, thereby reducing the natural oxide layer formed on the surface of the wafer to be cleaned, so as to achieve the purpose of removing the particles and metal ions Sn. In addition, in this mass concentration range, a moderate etching rate can also be provided, which can ensure sufficient cleaning effect and prevent excessive etching on the surface of the wafer to be cleaned, thereby preventing the formation of Jut-type defects and new particles.

[0041] In the present disclosure, by controlling the action time of the cleaning solution containing O3 on the surface of the wafer to be cleaned, it can be ensured that the O3 in the cleaning solution is in sufficient contact with the surface of the wafer to generate an oxide layer with sufficient thickness to cover the particles on the surface of the wafer and improve the flatness of the surface of the wafer. Moreover, by controlling the action time of the cleaning solution containing O3 on the surface of the wafer to be cleaned, it can be ensured that it can chemically react with the metal ions Sn on the surface of the wafer, thereby achieving the purpose of removing the metal ions Sn on the surface of the wafer. Therefore, in the present disclosure, by controlling the action time of the cleaning solution containing O3 on the surface of the wafer to be cleaned, the cleaning efficiency can be improved, the cycle time required for cleaning can be reduced, and the cleaning effect of each part of the surface of the wafer to be cleaned can be uniform, thereby avoiding uneven cleaning caused by improper time control. In addition, by controlling the action time of the cleaning solution containing O3 on the surface of the wafer to be cleaned, the surface of the wafer to be cleaned can be prevented from being excessively oxidized, so as to maintain the surface properties and flatness of the wafer.

[0042] For Figure 1 In some possible embodiments of the technical solution shown in the figure, the volume concentration of O3 in the cleaning solution containing O3 is greater than or equal to 25ppm and less than or equal to 30ppm.

[0043] It can be understood that, if the volume concentration of O3 in the cleaning solution containing O3 is too low, an oxide layer with sufficient thickness may not be formed on the surface of the wafer, so as to effectively remove or reduce the particles and metal ions Sn on the surface of the wafer to be cleaned; and if the volume concentration of O3 is too high, the wafer to be cleaned may be damaged, for example, scratches, pits and other defects may occur on the surface of the wafer to be cleaned. Therefore, maintaining an appropriate O3 concentration range in the cleaning solution containing O3 is the key to ensuring the cleaning effect.

[0044] In some examples, the flow rate of the above-mentioned cleaning solution can be controlled to be greater than or equal to 0.9 L / min and less than or equal to 1.4 L / min, and the flow rate of the cleaning solution is controlled to be in the range of 0.9-1.4 L / min, so as to realize the synergistic optimization of wafer surface cleaning efficiency and quality through precise fluid dynamics design. The lower limit of the flow rate (0.9 L / min) ensures that the DHF, DIO3 and other chemical solutions uniformly cover the surface of the wafer, avoids incomplete etching of the local oxide layer or uneven thickness of the oxide layer due to insufficient flow rate, and reduces surface turbulent flow impact through stable laminar flow to prevent Jut-type protrusion defects; the upper limit of the flow rate (1.4 L / min) accelerates the stripping of the oxide layer and loose particles by enhancing the liquid shear force, and can improve the removal efficiency of metal ions (such as Sn) in the heavy etching stage (DHF for 30 seconds). The flow rate range cooperates with the stage time control (such as light etching for 4 seconds and heavy oxidation for 40 seconds), which can quickly remove the reaction by-products (such as fluorosilicate particles) and residual chemicals, reduce the risk of secondary deposition, and reduce the chemical consumption in the light oxidation cycle, taking into account the production cost and cleaning efficiency.

[0045] For Figure 1 As shown in the technical solution, in some possible embodiments, the cleaning method further comprises: The number of repetitions of sequentially and alternately performing the etching rotation cleaning and the oxidation rotation cleaning is greater than or equal to 3 times and less than or equal to 6 times.

[0046] In the cleaning process of the present disclosure, the particles and metal ions Sn on the surface of the wafer to be cleaned can be more effectively removed by alternately using the cleaning solution containing HF and the cleaning solution containing O3 multiple times. By accurately controlling the number of alternations, the use amount of the cleaning solution can be reduced while ensuring the cleaning effect and preventing excessive etching.

[0047] In some examples, between the etching rotation cleaning and the oxidation rotation cleaning, the above-mentioned cleaning method can further comprise: The deionized water is supplied to the wafer to be cleaned to perform a first spin rinsing. It can be understood that new particles 203 are formed on the surface of the epitaxial wafer to be cleaned after etching by the cleaning solution containing HF. Therefore, in the present disclosure, the deionized water is used again to perform the first spin rinsing on the epitaxial wafer to be cleaned, so that the new particles 203 can be removed, and the cleaning solution remaining on the surface of the epitaxial wafer to be cleaned can also be removed, thereby ensuring the cleanliness of the cleaned epitaxial wafer.

[0048] In some examples, after the last time of performing the oxidation spin cleaning, the cleaning method can further include supplying the deionized water to the wafer to be cleaned to perform a second spin rinsing with a cleaning time greater than or equal to 5 seconds and less than or equal to 10 seconds.

[0049] The deionized water (DIW) second spin rinsing (5-10 seconds) after the last time of oxidation spin cleaning can comprehensively improve the wafer surface cleanliness through the following technical effects: through the continuous flushing of the large-flow deionized water, the residual ozone water (DIO3) and the oxidation reaction by-products (such as unreacted hydroxyl radicals) on the wafer surface are completely removed, and the interference of the chemical substance residues on the subsequent processes is avoided; at the same time, the extension of the rinsing time can ensure that the deionized water fully wets the wafer edge and the microstructure area, and effectively flushes the loose particles (such as silicon or silicon oxide fragments) generated in the etching-oxidation cycle. In addition, by quickly removing the surface residual liquid film, water marks or microcrystals formed due to local uneven drying can be inhibited, and the hydrophilicity of the wafer surface is maintained. The accurate time control of 5-10 seconds can ensure the cleaning efficiency while avoiding the excessive extension of the process cycle, thereby balancing the production capacity of the single wafer cleaning machine and the optimization demand of the wafer surface quality.

[0050] The technical solutions of the present disclosure are described in detail below through specific examples.

[0051] In the examples 1-10 and the comparative examples 1-2, when the wafer to be cleaned is cleaned, the duration of the first etching spin cleaning, the duration of the subsequent etching spin cleaning, the last oxidation cleaning time, the duration of the previous oxidation spin cleaning, the alternating number, the ozone concentration, the HF concentration setting, the cleaning solution flow, and the second rinsing time setting are set according to the following table 1. At this time, the particle content with a size less than or equal to 19 nm on the surface of the cleaned wafer after cleaning, the number of protrusion defects on the surface of the wafer, and the number of metal ions Sn on the surface of the wafer are shown in table 1: After summarizing the above examples and comparative examples, table 1 is obtained: Table 1

[0052] The duration of the first performed etching spin cleaning is greater than or equal to 20 seconds and less than or equal to 30 seconds; the duration of each subsequent etching spin cleaning is greater than or equal to 4 seconds and less than or equal to 10 seconds; the duration of the last performed oxidation spin cleaning is greater than or equal to 15 seconds and less than or equal to 40 seconds; the duration of each previous oxidation spin cleaning is greater than or equal to 5 seconds and less than or equal to 10 seconds; the wafer to be cleaned is supplied with the deionized water for a second spin rinse with a cleaning time greater than or equal to 5 and less than or equal to 10 seconds; the mass concentration of the HF in the cleaning solution containing the HF is greater than or equal to 0.3 wt% and less than or equal to 1.1 wt%; the volume concentration of the O3 in the cleaning solution containing the O3 is greater than or equal to 25 ppm and less than or equal to 30 ppm. The flow rate of the cleaning solution is greater than or equal to 0.9 L / min and less than or equal to 1.4 L / min. The number of times of sequentially alternating the etching spin cleaning and the oxidation spin cleaning is greater than or equal to 3 times and less than or equal to 6 times. After the cleaning of the wafer to be cleaned is completed using the above parameters, the content of particles with a size less than or equal to 19 nm on the surface of the cleaned wafer is greater than or equal to 0 ea and less than or equal to 10 ea, the number of protrusion defects on the surface of the cleaned wafer is greater than or equal to 0 ea and less than or equal to 4 ea, and the number of metal ions Sn on the surface of the cleaned wafer is less than or equal to 6 x 10 7 atom / cm 2 . Conversely, when any one of the above parameters is outside the above range, the parameters of the cleaned wafer do not meet the above parameters or irreversible damage to the wafer is caused.

[0053] It should be noted that the technical solutions disclosed in the present disclosure can be combined arbitrarily without conflict.

[0054] Finally, the present disclosure also provides a wafer, which is cleaned according to the cleaning method for a wafer according to the foregoing technical solutions, the content of particles with a size less than or equal to 19 nm on the surface of the cleaned wafer is greater than or equal to 0 ea and less than or equal to 10 ea, the number of protrusion defects on the surface of the cleaned wafer is greater than or equal to 0 ea and less than or equal to 4 ea, and the number of metal ions Sn on the surface of the cleaned wafer is less than or equal to 6 x 10 6 atom / cm 2 .

[0055] The above merely describes specific embodiments of the present disclosure, but the protection scope of the present disclosure is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present disclosure, which should be encompassed in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A method for cleaning wafers, characterized in that, The cleaning method includes: An HF-containing cleaning solution is supplied to the wafer to be cleaned to perform etch spin cleaning; Supplying an O3-containing cleaning solution to the wafer to be cleaned to perform oxidative spin cleaning; and The etching spin cleaning and the oxidation spin cleaning are performed alternately multiple times in sequence; The duration of the first etch rotation cleaning is longer than the duration of each subsequent etch rotation cleaning, and the duration of the last oxidation rotation cleaning is longer than the duration of each previous oxidation rotation cleaning.

2. The wafer cleaning method according to claim 1, characterized in that, The first etch spin cleaning completely etches the oxide layer on the surface of the wafer to be cleaned.

3. The wafer cleaning method according to claim 1, characterized in that, The duration of the first etching spin cleaning is 20-30 seconds; the duration of each subsequent etching spin cleaning is 4-10 seconds.

4. The wafer cleaning method according to claim 1, characterized in that, The duration of the final oxidation rotation cleaning is 15 to 40 seconds; the duration of each previous oxidation rotation cleaning is 5 to 10 seconds.

5. The wafer cleaning method according to claim 1, characterized in that, After the final oxidative spin cleaning, the method further includes: The wafer to be cleaned is supplied with deionized water for a second rotary rinse lasting 5 to 10 seconds.

6. The wafer cleaning method according to claim 1, characterized in that, In the HF-containing cleaning solution, the mass concentration of HF is 0.3wt% to 1.1wt%.

7. The wafer cleaning method according to claim 1, characterized in that, In the O3-containing cleaning solution, the volume concentration of O3 is 25 ppm to 30 ppm.

8. The wafer cleaning method according to claim 1, characterized in that, The flow rate of the cleaning fluid is 0.9 L / min to 1.4 L / min.

9. The wafer cleaning method according to claim 1, characterized in that, The etching spin cleaning and the oxidation spin cleaning are performed alternately a greater than or equal to 3 times and a less than or equal to 6 times.

10. The wafer cleaning method according to claim 1, characterized in that, Between the etching spin cleaning and the oxidation spin cleaning, the method further includes: Deionized water is supplied to the wafer to be cleaned to perform a first spin rinse.

11. A wafer, characterized in that, After the wafer is cleaned by the wafer cleaning method according to any one of claims 1 to 9, the content of particles with a size not greater than 19 nm on the surface of the wafer is at most 10ea, the number of protrusion defects on the surface of the wafer is at most 4ea, and the number of metal ions Sn on the surface of the wafer is not greater than 6 × 10⁻⁶. 7 atom / cm 2 .

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