A BOE etching solution composition
By improving the BOE etching solution with a fluorine-free, environmentally friendly surfactant, the problems of environmental pollution and insufficient wettability were solved, and the chemical stability and wettability were improved, thereby improving etching uniformity and device precision.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG SENMEI CHEM IND CO LTD
- Filing Date
- 2026-03-10
- Publication Date
- 2026-05-26
Smart Images
Figure CN121802415B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of semiconductor process materials technology, and specifically provides a BOE etching solution composition. Background Technology
[0002] Buffered oxide etchant (BOE) is a commonly used wet etching medium in semiconductor manufacturing, composed of hydrofluoric acid, ammonium fluoride, and ultrapure water. However, its high surface tension leads to insufficient wettability on the wafer surface, easily causing pattern distortion and uneven etching, affecting device accuracy and yield. To improve this problem, surfactants are usually added to BOE to reduce surface tension.
[0003] Due to the highly corrosive HF or fluoride anions in BOE solutions, conventional surfactants are difficult to maintain stability in this environment. Currently, perfluorinated and polyfluoroalkyl substances (PFAS) surfactants, such as FC-95, NOVEC4300, and NOVEC4200, are widely used in BOE. These substances exhibit excellent chemical stability and extremely low surface tension due to their high C–F bond energy and low intermolecular forces, enabling them to remain stable in BOE and significantly improve the wetting and etching uniformity of BOE.
[0004] However, PFAS are extremely difficult to degrade in the natural environment, can persist for a long time and migrate into water, soil and atmosphere, and produce bioaccumulation effects through the food chain, posing a serious threat to ecosystems and human health. They have been listed as restricted substances by many international conventions.
[0005] Therefore, developing a fluorine-free surfactant with high chemical stability, excellent wetting properties, and environmental friendliness is of great significance to the development of this industry. Summary of the Invention
[0006] To address the aforementioned technical problems, this invention provides a BOE etching solution composition. The surfactant in the BOE etching solution composition provided by this invention is a fluorine-free, environmentally friendly material, and the BOE etching solution composition provided by this invention exhibits excellent chemical stability and wettability.
[0007] The present invention solves the above-mentioned technical problems through the following technical solutions.
[0008] This invention provides a BOE etching solution composition, which is prepared by mixing electronic-grade hydrofluoric acid, electronic-grade ammonium fluoride, and a surfactant, wherein:
[0009] The surfactant is .
[0010] In this invention, the mass concentration of the electronic-grade hydrofluoric acid is 49 wt%.
[0011] In this invention, the mass concentration of the electronic-grade ammonium fluoride is 40 wt%.
[0012] In this invention, the volume ratio of the electronic-grade ammonium fluoride to the electronic-grade hydrofluoric acid is (6-20):1, for example, 6:1, 7:1, 10:1, 15:1 and 20:1.
[0013] In this invention, the surfactant accounts for 0.005%-0.2% of the total weight of the etching solution, for example, 0.1%.
[0014] In this invention, the BOE etching solution composition further comprises additives, wherein the additives are one or more of organic acids and / or organic bases and inorganic acids.
[0015] In this invention, when the additive is an organic acid, the organic acid is one or more of succinic acid, lactic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, and triethylpropionic acid.
[0016] In this invention, when the additive is an organic base, the organic base includes one or more of ethanolamine, triethanolamine, heptamine, decamine, undecamine, and dodecamine.
[0017] In this invention, the additive has a weight percentage of 0.005%-0.2%, for example, 0.1%.
[0018] The present invention also provides a compound, which is .
[0019] The present invention also provides an application of the above-mentioned compound as a surfactant; preferably, its application as a surfactant in BOE.
[0020] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.
[0021] The reagents and raw materials used in this invention are all commercially available.
[0022] The positive and progressive effects of the present invention are as follows: the surfactant in the BOE etching solution composition provided by the present invention is a fluorine-free environmentally friendly material, and the BOE etching solution composition provided by the present invention has excellent chemical stability and wettability. Attached Figure Description
[0023] Figure 1 The image shows the 1H NMR spectrum of surfactant 1 from Example 1.
[0024] Figure 2 The NMR fluorine spectra of BOE with surfactant 1 from Example 1 added at 0 hours and 48 hours were obtained.
[0025] Figure 3 NMR fluorine spectra of BOE with added dodecylbenzenesulfonic acid at 0 h and 48 h.
[0026] Figure 4 The contact angle test results on a silicon wafer for BOE with surfactant 1 from Example 1 added.
[0027] Figure 5 The results of contact angle tests on silicon wafers for BOE with added dodecylbenzenesulfonic acid. Detailed Implementation
[0028] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.
[0029] Example 1
[0030]
[0031] first step
[0032] Compound 1 ( Synthesis of )
[0033] Under nitrogen protection, 2,6-di-tert-butylphenol (40 g, 193.9 mmol) was dissolved in chlorobenzene (100 mL), 18 mL of concentrated sulfuric acid was added, the mixture was heated to 130 °C and stirred for 8 hours, cooled to room temperature, and the solid was collected by filtration. The solid was then slurried with n-hexane to give compound 1 (48 g, yield 86.5%). 1 H NMR (400 MHz, Methanol- d4 ): δ 1.46 (s, 18H), 7.71 (s, 2H).
[0034] Step 2
[0035] Compound 2 ( Synthesis of )
[0036] Compound 1 (48.0 g, 167.6 mmol) was reacted with dodecane bromo (48.0 g, 192.75 mmol) and sodium hydroxide (26.81 g, 670.4 mmol) in a mixture of methanol (200 ml). The mixture was stirred under reflux until TLC showed complete reaction. The mixture was then filtered, the solvent was removed under reduced pressure, and the mixture was slurried with n-hexane to give compound 2 (70.0 g, 91.85%). 1 H NMR (400 MHz, DMSO- d 6) δ 7.75 (s, 2H), 6.34 (s, 1H), 4.01 (t, 2H), 1.81-1.77 (m, 2H), 1.52-1.38 (m, 2H), 1.39 (s, 18H), 1.36-1.25(m, 16H), 0.77 (t, 3H).
[0037] Step 3
[0038] Surfactant 1 ( Synthesis of )
[0039] Compound 2 (10 g, 21.99 mmol) was added to thionyl chloride (50 mL) and heated under reflux for 2 hours. Excess thionyl chloride was then removed by vacuum distillation to obtain an intermediate. DMF (100 mL) and 3-aminocyclohexanol (3.04 g, 26.39 mmol) were then added and the mixture was heated under reflux until TLC showed complete reaction. Excess solvent was removed under reduced pressure, and the intermediate was obtained by rapid column chromatography (EA:MeOH = 99:1) to give surfactant 1 (7.65 g, 63.03%). 1 H NMR (400 MHz, CDCl3) δ 7.74 (s,2H), 5.77-5.74 (m, 1H), 3.98 (t, 2H), 3.71-3.67 (m, 1H), 3.03-2.96 (m, 1H),1.82-1.62 (m, 6H), 1.62-1.37 (m, 24H), 1.37-1.22 (m, 16H), 0.79 (t, 3H).
[0040] Example 2
[0041] Preparation of BOE Etching Solution Composition
[0042] S1: Surfactant 1 was purified by vacuum distillation under conditions of pressure below 10 Pa. The fraction collected at 225-227℃ was tested by HPLC and found to have a purity greater than 99.9%.
[0043] S2: Prepare BOE of different specifications according to the etching rate requirements; for example, electronic grade ammonium fluoride (40wt%) and electronic grade hydrofluoric acid (49wt%) are prepared in a volume ratio of (6-20):1, such as 6:1, 7:1, 10:1, 15:1 and 20:1 to prepare BOE of different specifications. Specifically, electronic grade ammonium fluoride (40wt%) and electronic grade hydrofluoric acid (49wt%) are added to the reactor in a volume ratio of 6:1 and stirred thoroughly to obtain a hydrofluoric acid-ammonium fluoride solution.
[0044] S3: Add 0.1 parts by weight of surfactant 1 to every 100 parts by weight of hydrofluoric acid-ammonium fluoride solution, and stir thoroughly to obtain the BOE etching solution composition.
[0045] Preferably, in S3, the above-mentioned BOE etching solution composition may further contain 0.1 parts by weight of additives, such as one or more of succinic acid, lactic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, triethylpropionic acid, ethanolamine, triethanolamine, heptamine, decamine, undecylamine, and dodecylamine.
[0046] Example 3
[0047] Stability testing of surfactants in BOE.
[0048] 1 mg of surfactant with a purity of 99.9% or higher, 0.3 mL of hydrofluoric acid-ammonium fluoride solution from step S2 of Example 2, and 0.2 mL of D2O were added to an NMR tube for F-spectrum analysis. After 48 hours, another F-spectrum analysis was performed. The experimental results... Figure 2 As shown.
[0049] Add 1 mg of dodecylbenzenesulfonic acid, 0.3 mL of the hydrofluoric acid-ammonium fluoride solution from step S2 of Example 2, and 0.2 mL of D2O to an NMR tube and perform an F-spectrum test. After 48 hours, perform another F-spectrum test. The experimental results... Figure 3 As shown.
[0050] The experimental results showed that BOE with added dodecylbenzenesulfonic acid exhibited multiple sets of impurity peaks, indicating that dodecylbenzenesulfonic acid reacted chemically with the BOE solution. However, BOE with added surfactant 1 of this invention showed almost no change within 48 hours. This demonstrates that the surfactant provided by this invention is chemically stable and can exist stably in BOE. The reason for this may be that the surfactant provided by this invention introduces a tert-butyl group, whose unhindered steric hindrance effectively prevents the F atom from attacking the H atom on the benzene ring, thereby enabling the surfactant of this invention to exist stably in BOE.
[0051] Example 4
[0052] Contact angle test. The contact angles of the hydrofluoric acid-ammonium fluoride solution (BOE without surfactant) in step S2 and the BOE etching solution composition (BOE with surfactant 1 of the present invention added) in step S3 of Example 2 on silicon wafers were tested using a surface tension meter. The experimental results are as follows: Figure 4 and Figure 5 As shown in Table 1 below, the overview is as follows.
[0053] Table 1
[0054]
[0055] The contact angle test results show that, compared with BOE without surfactant, the surface tension of BOE with surfactant 1 provided by the present invention is significantly reduced, and its contact angle is reduced from 60.7° to 38.2°.
[0056] In summary, the surfactant provided by this invention not only exists stably in BOE and exhibits excellent chemical stability, but also significantly reduces the surface tension of BOE, demonstrating its superior wettability. Therefore, the surfactant provided by this invention can be used in BOE.
Claims
1. A BOE etching solution composition, characterized in that, It is made from a mixture of electronic-grade hydrofluoric acid, electronic-grade ammonium fluoride, and surfactants, wherein: The surfactant is .
2. The BOE etching solution composition as described in claim 1, characterized in that, The mass concentration of the electronic-grade hydrofluoric acid is 49 wt%.
3. The BOE etching solution composition as described in claim 1, characterized in that, The mass concentration of the electronic-grade ammonium fluoride is 40 wt%.
4. The BOE etching solution composition as described in claim 1, characterized in that, The volume ratio of the electronic-grade ammonium fluoride to the electronic-grade hydrofluoric acid is (6-20):
1.
5. The BOE etching solution composition as described in claim 1, characterized in that, The surfactant constitutes 0.1% of the total weight of the etching solution.
6. A compound, which is .
7. The use of the compound as a surfactant as claimed in claim 6.