Method for cleaning silicon wafer after acid corrosion
By optimizing the combined cleaning methods of alkaline solution, pure water ultrasound, acid solution, and pure water ultrasound, the problems of corrosion rate and surface morphology control in the post-acid etching treatment of silicon wafers were solved, achieving a highly efficient silicon wafer cleaning effect and improving production efficiency and cleanliness.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI SEMICON WAFER TECH CO LTD
- Filing Date
- 2025-12-22
- Publication Date
- 2026-04-14
AI Technical Summary
In the existing technology, the post-treatment of silicon wafers by acid etching presents challenges in controlling the etching rate and surface morphology, and the use of surfactants lacks systematic research and optimization schemes for specific process conditions.
A cleaning method under specific process conditions is adopted, including a combination of cleaning steps of alkaline solution, pure water ultrasound, acid solution and pure water ultrasound. Domestic chemical solutions such as TMAH and EC-7 or HF are used in the ratio with pure water. The cleaning temperature and time are optimized and combined with the spin-drying step to form a customized process.
It achieves cleaning efficiency comparable to similar foreign cleaning solutions, significantly reduces cleaning temperature and cycle, reduces the amount of cleaning solution used, improves production efficiency, and ensures that cleanliness standards are met.
Abstract
Description
Technical Field
[0001] This application relates to the field of silicon wafer cleaning, and in particular to a method for cleaning silicon wafers after acid etching. Background Technology
[0002] The cleaning process after acid etching of silicon wafers plays an important role in semiconductor manufacturing. Its core objective is to remove impurities and residues from the surface of silicon wafers in order to improve the performance and yield of subsequent processes.
[0003] Currently, post-acid etching of silicon wafers typically involves cleaning with alkaline solutions (such as TMAH) to remove surface residues and impurities. While TMAH (tetramethylammonium hydroxide) solution is a commonly used reagent for anisotropic etching of silicon wafers and exhibits good process compatibility, controlling its etching rate and surface morphology remains challenging. For example, adding surfactants can improve surface morphology, but excessive or improper use can lead to surface defects. Furthermore, existing technologies lack systematic research on the use of surfactants and optimization schemes tailored to specific process conditions.
[0004] Therefore, developing a new cleaning process that can reach or surpass advanced international levels by introducing specific surfactants and optimizing process conditions has significant technological value and market potential. Summary of the Invention
[0005] To address the aforementioned technical problems, this application provides a method for cleaning silicon wafers after acid etching, comprising the following steps:
[0006] 1) Clean the silicon wafer with alkaline solution for 1-10 minutes at a cleaning temperature of 50-80℃ to obtain the first silicon wafer;
[0007] 2) The first silicon wafer is ultrasonically cleaned with pure water at room temperature, with an overflow rate of 5-15 L / min and a cleaning time of 3-8 min, to obtain the second silicon wafer;
[0008] 3) Clean the second silicon wafer with acid at room temperature for 3-8 minutes to obtain the third silicon wafer;
[0009] 4) Use pure water at room temperature to ultrasonically clean the third silicon wafer. The overflow rate is 5-15 L / min, and the cleaning time is 3-8 min to obtain the fourth silicon wafer.
[0010] 5) Spin dry the fourth silicon wafer.
[0011] The beneficial effects of this application include, but are not limited to: by using specific domestically produced cleaning solutions, combined with customized process conditions that are highly compatible with their performance, not only can the cleaning efficiency be comparable to that of similar foreign cleaning solutions, but the cleaning temperature can also be significantly reduced, the cleaning cycle can be effectively shortened, and the amount of cleaning solution used can be reduced. While ensuring that the core cleanliness indicators meet the standards, the overall efficiency of the production process can be improved simultaneously. Detailed Implementation
[0012] To more clearly illustrate the technical solutions of the embodiments in this specification, a brief description of the embodiments will be provided below. Obviously, the following description is merely some examples or embodiments of this specification. For those skilled in the art, this specification can be applied to other similar scenarios without creative effort. Unless obvious from the linguistic context or otherwise specified, the same reference numerals represent the same structure or operation.
[0013] As indicated in this specification and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.
[0014] This specification uses procedures to illustrate the operations performed by the system according to embodiments of this specification. It should be understood that the preceding or following operations are not necessarily performed precisely in sequence. Instead, the steps can be processed in reverse order or simultaneously. Furthermore, other operations can be added to these procedures, or one or more steps can be removed from them.
[0015] Silicon wafers undergo rigorous cleaning during semiconductor device manufacturing. Even minute amounts of contamination can lead to device failure. The purpose of cleaning is to remove surface contaminants, including both organic and inorganic substances. These impurities exist on the silicon wafer surface in atomic or ionic states, as well as in thin film or particulate forms, and can cause various defects.
[0016] With the development of large-scale integrated circuits, the integration density is constantly increasing and the linewidth is constantly decreasing, the quality requirements for silicon wafers are also getting higher and higher, especially the surface quality requirements for silicon polished wafers are becoming more and more stringent.
[0017] In the production of silicon transistors and integrated circuits, silicon wafer cleaning is involved in almost every process. The quality of silicon wafer cleaning has a serious impact on device performance. Improper handling may cause all silicon wafers to be scrapped, making it impossible to manufacture transistors, or the manufactured devices may have poor performance, stability, and reliability.
[0018] This application provides a method for cleaning silicon wafers after acid etching, comprising the following steps:
[0019] 1) Clean the silicon wafer with alkaline solution for 1-10 minutes at a cleaning temperature of 50-80℃ to obtain the first silicon wafer;
[0020] 2) The first silicon wafer is ultrasonically cleaned with pure water at room temperature, with an overflow rate of 5-15 L / min and a cleaning time of 3-8 min, to obtain the second silicon wafer;
[0021] 3) Clean the second silicon wafer with acid at room temperature for 3-8 minutes to obtain the third silicon wafer;
[0022] 4) Use pure water at room temperature to ultrasonically clean the third silicon wafer. The overflow rate is 5-15 L / min, and the cleaning time is 3-8 min to obtain the fourth silicon wafer.
[0023] 5) Spin dry the fourth silicon wafer.
[0024] In some embodiments, the alkaline solution in step 1) can be prepared from TMAH solution, EC-7 solution and pure water.
[0025] In some embodiments, the volume ratio of the TMAH solution, EC-7 solution, and pure water can be (2-4):(0.5-1):(48-50.5). In some embodiments, the volume ratio of the TMAH solution, EC-7 solution, and pure water can be (2.5-3.5):(0.75-1):(48.5-50). In some embodiments, the volume ratio of the TMAH solution, EC-7 solution, and pure water can be (3.0-3.5):(0.75-1):(49-49.5).
[0026] In some embodiments, the concentration of the TMAH solution can be 26 wt%, and the concentration of the EC-7 solution can be 12 wt%.
[0027] In some embodiments, in step 2), the overflow rate can be 10 L / min and the cleaning time can be 5 min.
[0028] In some embodiments, in step 3), the acid solution can be prepared from HF solution and pure water. In some embodiments, preferably, in step 3), the volume ratio of the HF solution to pure water can be (2-8):(40-50). In some embodiments, preferably, in step 3), the volume ratio of the HF solution to pure water can be (3-7):(42-48). In some embodiments, preferably, in step 3), the volume ratio of the HF solution to pure water can be (4-6):(44-46).
[0029] In some embodiments, more preferably, in step 3), the volume ratio of the HF solution to pure water can be 5:45.
[0030] In some embodiments, the cleaning time in step 3) can be 5 minutes.
[0031] In some embodiments, the concentration of the HF solution can be 40–60 wt%. In some embodiments, the concentration of the HF solution can be 42–58 wt%. In some embodiments, the concentration of the HF solution can be 44–56 wt%. In some embodiments, the concentration of the HF solution can be 46–54 wt%. In some embodiments, the concentration of the HF solution can be 48–52 wt%. In some embodiments, the concentration of the HF solution can be 50–52 wt%.
[0032] In some embodiments, the concentration of the HF solution may be 49 wt%.
[0033] In some embodiments, in step 4), the overflow rate can be 10 L / min and the cleaning time can be 5 min.
[0034] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the experimental materials used in the following examples were all purchased from conventional biochemical reagent companies. All quantitative experiments in the following examples were performed in triplicate, and the results were averaged.
[0035] Example 1:
[0036] Step 1: Clean with an alkaline solution, which includes TMAH, domestic surfactant EC-7, and pure water in a volume ratio of 2:0.5:50.5. The mass percentage concentration of TMAH solution is 26wt%, and the mass percentage concentration of EC-7 solution is 12wt%. The cleaning temperature is 68℃, and the cleaning time is 5min.
[0037] Step 2: Clean with pure water at room temperature, with an overflow rate of 10L / min and a cleaning time of 5 minutes. Turn on the ultrasonic cleaner.
[0038] Step 3: Clean with acid solution, which includes HF and pure water in a volume ratio of 5:45. The HF solution has a mass percentage concentration of 49wt%. The cleaning temperature is room temperature and the cleaning time is 5 minutes.
[0039] Step 4: Clean with pure water at room temperature, with an overflow rate of 10L / min and a cleaning time of 5 minutes. Turn on the ultrasonic cleaner.
[0040] Step 5: Use a spin dryer to dry the silicon wafers.
[0041] Example 2:
[0042] Step 1: Clean with an alkaline solution, which includes TMAH, domestic surfactant EC-7, and pure water in a volume ratio of 2:1:50. The mass percentage concentration of TMAH solution is 26wt%, and the mass percentage concentration of EC-7 solution is 12wt%. The cleaning temperature is 68℃, and the cleaning time is 5min.
[0043] Step 2: Clean with pure water at room temperature, with an overflow rate of 10L / min and a cleaning time of 5 minutes. Turn on the ultrasonic cleaner.
[0044] Step 3: Clean with acid solution, which includes HF and pure water in a volume ratio of 5:45. The HF solution has a mass percentage concentration of 49wt%. The cleaning temperature is room temperature and the cleaning time is 5 minutes.
[0045] Step 4: Clean with pure water at room temperature, with an overflow rate of 10L / min and a cleaning time of 5 minutes. Turn on the ultrasonic cleaner.
[0046] Step 5: Use a spin dryer to dry the silicon wafers.
[0047] Example 3:
[0048] Step 1: Clean with an alkaline solution, which includes TMAH, domestic surfactant EC-7, and pure water in a volume ratio of 4:1:48. The mass percentage concentration of TMAH solution is 26wt%, and the mass percentage concentration of EC-7 solution is 12wt%. The cleaning temperature is 68℃, the cleaning time is 5 minutes, and the ultrasonic cleaning is turned on.
[0049] Step 2: Clean with pure water at room temperature, with an overflow rate of 10L / min and a cleaning time of 5min.
[0050] Step 3: Clean with acid solution, which includes HF and pure water in a volume ratio of 5:45. The HF solution has a mass percentage concentration of 49wt%. The cleaning temperature is room temperature and the cleaning time is 5 minutes.
[0051] Step 4: Clean with pure water at room temperature, with an overflow rate of 10L / min and a cleaning time of 5 minutes. Turn on the ultrasonic cleaner.
[0052] Step 5: Use a spin dryer to dry the silicon wafers.
[0053] Comparative example:
[0054] Step 1: Clean with an alkaline solution, which includes TMAH, imported surfactant PC-DH2, and pure water in a volume ratio of 4:1:48. The mass percentage concentration of TMAH solution is 26wt%, and the mass percentage concentration of PC-DH2 solution is 10-15wt%. The cleaning temperature is 81℃, and the cleaning time is 8min.
[0055] Step 2: Clean with pure water at room temperature, with an overflow rate of 10L / min and a cleaning time of 8 minutes. Turn on the ultrasonic cleaner.
[0056] Step 3: Clean with an acid solution, which includes HF and pure water in a volume ratio of 5:45. The HF solution has a mass percentage concentration of 49wt%. The cleaning temperature is room temperature and the cleaning time is 8 minutes.
[0057] Step 4: Clean with pure water at room temperature, with an overflow rate of 10L / min and a cleaning time of 8 minutes. Turn on the ultrasonic cleaner.
[0058] Step 5: Use a spin dryer to dry the silicon wafers.
[0059] Table 1 Performance data of each formulation
[0060] formula Example 1 Example 2 Example 3 formula Comparative Example TMAH(L) 2 2 4 TMAH(L) 4 EC-7(L) 0.5 1 1 PC-DH2(L) 1 Pure water (L) 50.5 50 48 Pure water (L) 48 Washing temperature (°C) 68 68 68 Washing temperature (°C) 81 Washing time (min) 5 5 5 Washing time (min) 8 test Example 1 Example 2 Example 3 test Comparative Example Wash the number of pieces 19512 18637 18611 Wash the number of pieces 17122 Yield 99.75％ 99.73％ 99.82％ Yield 99.73％
[0061] The basic concepts have been described above. Obviously, for those skilled in the art, the detailed disclosure above is merely illustrative and does not constitute a limitation of this specification. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this specification. Such modifications, improvements, and corrections are suggested in this specification and therefore remain within the spirit and scope of the exemplary embodiments described herein.
[0062] Furthermore, this specification uses specific terms to describe embodiments thereof. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of this specification. Therefore, it should be emphasized and noted that references to "an embodiment," "one embodiment," or "an alternative embodiment" in different locations throughout this specification do not necessarily refer to the same embodiment. Moreover, certain features, structures, or characteristics in one or more embodiments of this specification can be appropriately combined.
[0063] In some embodiments, numbers describing the quantity of components and attributes are used. It should be understood that such numbers used in the description of embodiments are modified in some examples with the terms "approximately," "approximately," or "generally." Unless otherwise stated, "approximately," "approximately," or "generally" indicates that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may be changed depending on the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit reservation. Although the numerical ranges and parameters used to confirm their breadth of range in some embodiments of this specification are approximate values, in specific embodiments, such values are set as precisely as feasible.
[0064] Finally, it should be understood that the embodiments described in this specification are merely illustrative of the principles of the embodiments described herein. Other variations may also fall within the scope of this specification. Therefore, alternative configurations of the embodiments described herein are intended to be illustrative rather than limiting, and should be considered consistent with the teachings of this specification. Accordingly, the embodiments described herein are not limited to those explicitly introduced and described herein.
Claims
1. A method for cleaning silicon wafers after acid etching, characterized in that, Includes the following steps: 1) Clean the silicon wafer with alkaline solution for 1-10 minutes at a cleaning temperature of 50-80℃ to obtain the first silicon wafer; 2) The first silicon wafer is ultrasonically cleaned with pure water at room temperature, with an overflow rate of 5-15 L / min and a cleaning time of 3-8 min, to obtain the second silicon wafer; 3) Clean the second silicon wafer with acid at room temperature for 3-8 minutes to obtain the third silicon wafer; 4) Use pure water at room temperature to ultrasonically clean the third silicon wafer. The overflow rate is 5-15 L / min, and the cleaning time is 3-8 min to obtain the fourth silicon wafer. 5) Spin dry the fourth silicon wafer.
2. The method as described in claim 1, characterized in that, In step 1), the alkaline solution is prepared by mixing TMAH solution, EC-7 solution and pure water.
3. The method as described in claim 2, characterized in that, The volume ratio of the TMAH solution, EC-7 solution and pure water is (2-4):(0.5-1):(48-50.5).
4. The method as described in claim 2, characterized in that, The concentration of the TMAH solution is 26 wt%, and the concentration of the EC-7 solution is 12 wt%.
5. The method as described in claim 1, characterized in that, In step 2), the overflow rate is 10 L / min and the cleaning time is 5 min.
6. The method as described in claim 1, characterized in that, In step 3), the acid solution is prepared by mixing HF solution and pure water. Preferably, the volume ratio of HF solution to pure water is (2-8):(40-50), and more preferably, the volume ratio of HF solution to pure water is 5:
45.
7. The method as described in claim 1, characterized in that, The cleaning time in step 3) is 5 minutes.
8. The method as described in claim 6, characterized in that, The concentration of the HF solution is 40–60 wt%.
9. The method as described in claim 6, characterized in that, The concentration of the HF solution is 49 wt%.
10. The method as described in claim 1, characterized in that, In step 4), the overflow rate is 10 L / min and the cleaning time is 5 min.