Quartz crystal etching solution

Abstract

The present application relates to a kind of etching solution for quartz crystal.The etching solution is composed of the following components according to mass percentage, 20% hydrofluoric acid, 15% nitric acid, 0.15-0.7% additive, and the rest is ultrapure water.The four-component additive includes sodium butylnaphthalene sulfonate, PE6400, 1-butyl-3-methylimidazolium tetrafluoroborate, 4-mercapto butyric acid.Among them, sodium butylnaphthalene sulfonate prevents the aggregation and deposition of particles generated during etching, maintains the clarity and uniformity of the etching solution.PE6400 has both hydrophilic and hydrophobic properties, and plays a role in solubilization, dispersion and defoaming.The two can significantly reduce the protrusions remaining after etching of quartz crystal, reduce roughness, and make the surface more smooth.1-butyl-3-methylimidazolium tetrafluoroborate and 4-mercapto butyric acid can control the etching of quartz side, and produce symmetrical V-shaped structure.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor material processing technology, and specifically relates to a quartz crystal etching solution. Background Technology

[0002] In the manufacturing process of resonators, quartz crystals need to be precisely etched with tuning fork structures. A smooth, regular etched surface not only reduces the resonant resistance and aging rate of the crystal resonator but also ensures frequency consistency, thereby improving the resonator's performance stability and reliability. However, existing etchants often result in irregular shapes, asymmetry on both sides, and protruding residues. Therefore, developing an etchant with symmetrical, regular etchable shapes that reduces etching residue and produces a lower surface roughness after etching is particularly important. Summary of the Invention

[0003] To address the aforementioned problems, this invention aims to provide a quartz crystal etching solution designed to form symmetrical and regular lateral etching, reduce residues on the quartz crystal after etching, lower roughness, and make the surface smoother.

[0004] The technical solution of this invention is as follows:

[0005] A quartz crystal etching solution, the etching solution comprising the following components in mass fractions:

[0006] 15-25% hydrofluoric acid, 10-20% nitric acid, 0.15-0.7% additives, and the remainder is ultrapure water.

[0007] Preferably, the additive is sodium butylnaphthalene sulfonate, PE6400 (BASF Pluronic PE6400 is an ethylene oxide-propylene oxide copolymer), 1-butyl-3-methylimidazolium tetrafluoroborate, 4-mercaptobutyric acid, or a combination thereof.

[0008] Preferably, the etching solution comprises the following components by mass fraction: 15-25% hydrofluoric acid, 10-20% nitric acid, 0.01-0.083% sodium butylnaphthalene sulfonate, 0.075-0.45% PE6400, and the remainder is ultrapure water.

[0009] More preferably, the etching solution further includes the following components by mass fraction: 0.017-0.1% 1-butyl-3-methylimidazolium tetrafluoroborate.

[0010] More preferably, the etching solution further includes the following components by mass fraction: 0.033-0.1% 4-mercaptobutyric acid.

[0011] Preferably, the etching solution comprises the following components by mass fraction: 15-25% hydrofluoric acid, 12-16% nitric acid, 0.03-0.06% sodium butylnaphthalenesulfonate, 0.09-0.3% PE6400, 0.02-0.06% 1-butyl-3-methylimidazolium tetrafluoroborate, 0.045-0.85% 4-mercaptobutyric acid, with the remainder being ultrapure water.

[0012] The quartz crystal etching solution can be used for V-type etching of quartz crystals.

[0013] By adding additives to hydrofluoric acid and nitric acid, the etching solution of this invention can laterally etch to produce a symmetrical V-shaped structure, significantly reducing residual protrusions after quartz crystal etching, resulting in a smoother surface with lower roughness. This helps improve the performance and stability of the resonator.

[0014] Hydrofluoric acid and nitric acid are responsible for etching the quartz crystal; additives are used to improve the etching effect, control the lateral etching shape, reduce roughness, and minimize residue. Sodium butylnaphthalenesulfonate prevents particle aggregation and deposition during etching, maintaining the clarity and uniformity of the etching solution. PE6400, with both hydrophilic and hydrophobic properties, acts as a solubilizer, dispersant, and defoamer. Together, they significantly reduce residual protrusions after quartz crystal etching, lowering roughness and resulting in a smoother surface. 1-Butyl-3-methylimidazolium tetrafluoroborate and 4-mercaptobutyric acid work synergistically to control quartz lateral etching, producing a symmetrical V-shaped structure.

[0015] Compared with the prior art, the advantages of the present invention are as follows:

[0016] 1. Symmetrical side etching structure: The etching solution of this invention can generate a symmetrical V-shaped structure through side etching, ensuring the consistency of frequency.

[0017] 2. Reduced etching residue: The etching solution of this invention significantly reduces the residue on the quartz crystal after etching by adding a two-component additive, thereby improving the etching quality.

[0018] 3. Improved surface smoothness: The etched quartz crystal has a smoother surface, which helps with subsequent processes and improves the performance of the resonator.

[0019] 4. Process stability: The etching solution of this invention has a stable composition and is easy to control, which helps to improve the stability and reliability of the resonator manufacturing process. Attached Figure Description

[0020] Figure 1 The etching effect of the etching solution of this invention. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. These embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0022] In the context of this specification, except where expressly stated, any matters or issues not mentioned are made directly using techniques known in the art. Furthermore, any embodiment described in this patent can be freely combined with one or more other embodiments described in this patent, and the resulting technical solutions or ideas shall be considered part of the original disclosure or original record of this invention, and should not be regarded as new content not disclosed in this patent, unless those skilled in the art consider the combination to be clearly unreasonable.

[0023] The data points disclosed in this invention include not only the specifically disclosed numerical points, but also the endpoints of each numerical range. Any combination of these data points should be considered as the range disclosed or described in this invention, regardless of whether each of these numerical points is disclosed herein.

[0024] Examples 1-22 and Comparative Examples 1-10

[0025] The present invention will be further illustrated below with reference to specific embodiments 1-22 and comparative examples 1-10. The present invention will be described in further detail, but is not limited to these embodiments.

[0026] According to the mass percentages in Table 1 (based on 100%, with the remainder being ultrapure water), the components were mixed evenly to obtain the etching solution of this invention. The tuning fork structure sheet was placed in the above etching solution and etched at 48 ℃ and 50 r / min for 3.5 h. The structure sheet was then removed, rinsed in ultrapure water for 5 min, and dried in a 90 ℃ oven. The roughness was measured and the surface morphology was observed.

[0027] Table 1

[0028]

[0029] As shown in Table 1, the etchant solution of this invention produces structural sheets with low surface roughness. In the comparative example without sodium butylnaphthalenesulfonate and PE6400, the roughness is higher, indicating that these two additives work synergistically to make the etched surface smoother. 1-Butyl-3-methylimidazolium tetrafluoroborate and 4-mercaptobutyric acid have little effect on roughness; their role is to control the lateral etching morphology and improve symmetry. Etching with hydrofluoric acid results in high roughness, but as the main etchant, hydrofluoric acid cannot be replaced by other acids. Adding nitric acid can assist etching and also reduce roughness. Adding phosphoric acid does not have this effect.

[0030] The technical solutions of the present invention have been explained through the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above specific embodiments to be implemented. Any improvements made by those skilled in the art based on the present invention, or equivalent substitutions for the materials selected in the present invention, fall within the scope of patent protection.

Claims

1. A quartz crystal etching solution, characterized in that: The etching solution comprises the following components by mass fraction: 15-25% hydrofluoric acid, 10-20% nitric acid, 0.01-0.083% sodium butylnaphthalenesulfonate, 0.075-0.45% PE6400, 0.017-0.1% 1-butyl-3-methylimidazolium tetrafluoroborate, 0.033-0.1% 4-mercaptobutyric acid, with the remainder being ultrapure water.

2. The quartz crystal etching solution according to claim 1, characterized in that: The etching solution comprises the following components by mass fraction: 15-25% hydrofluoric acid, 12-16% nitric acid, 0.03-0.06% sodium butylnaphthalene sulfonate, 0.09-0.3% PE6400, 0.02-0.06% 1-butyl-3-methylimidazolium tetrafluoroborate, 0.045-0.85% 4-mercaptobutyric acid, with the remainder being ultrapure water.

3. The use of the quartz crystal etching solution according to any one of claims 1-2 for V-type etching of quartz crystals.

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