Quartz crystal etching solution

Abstract

The invention relates to an etching solution for a quartz crystal. The etching liquid is prepared from the following components in percentage by mass: 20% of hydrofluoric acid, 15% of nitric acid, 0.15-0.7% of an additive and the balance of ultrapure water. The four-component additive is prepared from sodium butyl naphthalene sulfonate, PE6400, 1-butyl-3-methylimidazolium tetrafluoroborate and 4-mercaptobutyric acid. Wherein the sodium butylnaphthalenesulfonate prevents particles generated in the etching process from being gathered and deposited, and the clearness and uniformity of the etching liquid are kept. PE6400 has both hydrophilicity and hydrophobicity, and has the effects of assisting in dissolving, dispersing and defoaming. The cooperation of the two can significantly reduce the residual protrusions after the quartz crystal is etched, reduce the roughness, and make the surface smoother. The 1-butyl-3-methylimidazolium tetrafluoroborate and the 4-mercaptobutyric acid cooperate to control lateral erosion of quartz, and a symmetrical V-shaped structure is generated.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor material processing, and in particular relates to a quartz crystal etching liquid. Background Art

[0002] During the resonator manufacturing process, the quartz crystal needs to be precisely etched into a tuning fork structure. A smooth, regular side-etched surface can not only reduce the resonant resistance and aging rate of the crystal resonator, but also ensure the consistency of the frequency, thereby improving the performance stability and reliability of the resonator. However, the side-etching of existing etching solutions often forms irregular shapes, asymmetric left and right sides, and causes convex residues. Therefore, it is particularly important to develop an etching solution with symmetrical and regular side-etching shapes that can reduce etching residues and make the surface after etching have a lower roughness. Summary of the invention

[0003] In order to solve the above problems, the present invention aims to provide a quartz crystal etching solution, which aims to form symmetrical and regular shaped side etching, reduce the residue on the quartz crystal after etching, reduce the roughness, and make the surface smoother.

[0004] The technical solution of the present invention is as follows: A quartz crystal etching solution, comprising the following components by mass fraction: 15-25% hydrofluoric acid, 10-20% nitric acid, 0.15-0.7% additives, and the rest is ultrapure water.

[0005] Preferably, the additive is sodium butylnaphthalene sulfonate, PE6400 (BASF Pluronic PE6400 is an ethylene oxide-propylene oxide copolymer), 1-butyl-3-methylimidazole tetrafluoroborate, 4-mercaptobutyric acid or a combination thereof.

[0006] Preferably, 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, and the rest is ultrapure water.

[0007] Further preferably, the etching solution further comprises the following components in terms of mass fraction: 0.017-0.1% 1-butyl-3-methylimidazolium tetrafluoroborate.

[0008] More preferably, the etching solution further comprises the following components in terms of mass fraction: 0.033-0.1% 4-mercaptobutyric acid.

[0009] 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, and the rest is ultrapure water.

[0010] The quartz crystal etching liquid can be used for quartz crystal V-shaped etching.

[0011] By adding additives to hydrofluoric acid and nitric acid, the etching solution of the present invention can produce a symmetrical V-shaped structure by side etching, significantly reducing the residual protrusions after etching the quartz crystal, making the surface smoother and having a lower roughness, which helps to improve the performance and stability of the resonator.

[0012] Among them, hydrofluoric acid and nitric acid are responsible for etching quartz crystals; additives are used to improve the etching effect, control the shape of side etching, reduce roughness, and reduce residue. Sodium butylnaphthalene sulfonate prevents the aggregation and deposition of particles generated during the etching process, and maintains the clarity and uniformity of the etching solution. PE6400 is both hydrophilic and hydrophobic, and plays a role in solubilization, dispersion, and defoaming. The two can work together to significantly reduce the protrusions remaining after etching the quartz crystal, reduce roughness, and make the surface smoother. 1-Butyl-3-methylimidazole tetrafluoroborate and 4-mercaptobutyric acid can work together to control the side etching of quartz and produce a symmetrical V-shaped structure.

[0013] Compared with the prior art, the advantages of the present invention are: 1. Symmetrical side etching structure: The etching solution of the present invention can produce a symmetrical V-shaped structure by side etching to ensure the consistency of frequency.

[0014] 2. Reducing etching residue: The etching solution of the present invention significantly reduces the residue on the quartz crystal after etching by adding a two-component additive, thereby improving the etching quality.

[0015] 3. Improve surface flatness: The surface of the quartz crystal after etching is smoother, which is helpful for subsequent processes and the improvement of resonator performance.

[0016] 4. Process stability: The etching solution of the present invention has stable composition and is easy to control, which helps to improve the stability and reliability of the resonator manufacturing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The etching solution of the present invention has good etching effect. DETAILED DESCRIPTION

[0018] The following will be combined with the specific embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. The embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0019] In the context of this specification, except for the contents explicitly described, any matters or items not mentioned directly use the technology known in the art. Moreover, any embodiment described in this patent can be freely combined with one or more other embodiments described in this patent, and the technical solutions or technical ideas formed thereby are regarded as part of the original disclosure or original record of the present invention, and should not be regarded as new content not disclosed in this patent, unless a person skilled in the art considers that the combination is obviously unreasonable.

[0020] The data points disclosed in the present 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 regarded as the disclosed or recorded range of the present invention, regardless of whether these numerical points are disclosed one by one in this article. Examples 1-22 and Comparative Examples 1-10 The present invention is further described below in conjunction with specific examples 1-22 and comparative examples 1-10. The present invention is further described in detail, but is not limited to these examples.

[0021] According to the mass percentage in Table 1 (100%, the remainder is ultrapure water), the components are mixed evenly to obtain the etching solution of the present invention. The tuning fork structure sheet is placed in the above etching solution, etched for 3.5 hours at 48 ° C and 50 r / min. The structure sheet is taken out and rinsed in ultrapure water for 5 minutes, placed in a 90 ° C oven for drying, and the roughness is measured and the surface morphology is observed. Table 1

[0022] As can be seen from the results in Table 1, the structural sheet etched by the etching solution of the present invention has a lower surface roughness. In the comparative example where sodium butylnaphthalene sulfonate and PE6400 are not added, the roughness is higher, which shows that the two additives work synergistically to make the surface smoother after etching. However, 1-butyl-3-methylimidazole tetrafluoroborate and 4-mercaptobutyric acid have little effect on the roughness, and the role of these two is to control the side etching morphology and improve the symmetry. After etching with monohydrofluoric acid, the roughness is higher, but hydrofluoric acid, as the main etching agent, cannot be replaced by other acids. Adding nitric acid can assist etching and also play a role in reducing roughness. If phosphoric acid is added, there is no such effect.

[0023] The technical solution of the present invention is 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 technicians in the relevant field based on the present invention, or equivalent replacement of the materials selected by the present invention, etc., fall within the scope of protection of the patent.

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, 0.15-0.7% additives, and the rest is ultrapure water.

2. The quartz crystal etching solution according to claim 1, characterized in that: The additive is sodium butylnaphthalene sulfonate, PE6400, 1-butyl-3-methylimidazole tetrafluoroborate, 4-mercaptobutyric acid or a combination thereof.

3. 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, 10-20% nitric acid, 0.01-0.083% sodium butylnaphthalene sulfonate, 0.075-0.45% PE6400, and the rest is ultrapure water.

4. The quartz crystal etching solution according to claim 3, characterized in that: The etching solution also includes the following components by mass fraction: 0.017-0.1 % 1-butyl-3-methylimidazolium tetrafluoroborate.

5. The quartz crystal etching solution according to claim 4, characterized in that: The etching solution also includes the following components by mass fraction: 0.033-0.1% 4-mercaptobutyric acid.

6. 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 butylnaphthalenesulfonate, 0.09-0.3% PE6400, 0.02-0.06% 1-butyl-3-methylimidazolium tetrafluoroborate, 0.045-0.85% 4-mercaptobutyric acid, and the rest is ultrapure water.

7. The quartz crystal etching solution according to any one of claims 1 to 6, characterized in that: The quartz crystal etching liquid can be used for quartz crystal V-shaped etching.

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