A quartz vibrating beam processing method based on selective etching of frequency-doubled Bessel laser

Abstract

The application discloses a quartz vibrating beam processing method based on selective etching of frequency-doubled Bessel laser and belongs to the technical field of femtosecond laser application. In the application, a Z-cut alpha quartz wafer is double-side plated with a gold film, a resonator pattern is etched on the gold film by using a photoetching and plasma etching process, and the resonator pattern is used as a protective layer of the etching process and a surface electrode of a subsequent accelerometer. A femtosecond laser Gaussian light beam is spatially integrated into a Bessel light beam with a long focal depth by using a cone lens, the Bessel light beam is shrunk by using a plano-convex lens and a focusing objective lens to form a 4F system, and the Bessel light beam is focused in the quartz wafer. The quartz wafer is scanned and processed along the above-mentioned resonator pattern profile. After the Z-cut quartz crystal is irradiated by the femtosecond laser, the quartz crystal structure in the irradiation area is amorphized, the etching rate of the irradiation area in a hydrofluoric acid solution is accelerated, the sample is separated along the modified profile after etching, and the quartz vibrating beam is obtained. The application has the advantages of high perpendicularity of the vibrating beam sidewall, good uniformity and no side etching.

Description

TECHNICAL FIELD

[0001] The application relates to a method for processing a quartz vibrating beam resonator by frequency-doubled Bessel laser selective etching, and belongs to the technical field of femtosecond laser application. BACKGROUND

[0002] The quartz vibrating beam accelerometer is an acceleration sensor device which relies on the piezoelectric effect of a quartz crystal and takes a force-sensitive quartz vibrating beam resonator as a core sensitive element, has the characteristics of directly outputting a digital signal without digital-to-analog conversion, simple structure, small size, high sensitivity, high frequency stability and the like, and is an important component of an inertial instrument. A core component of the quartz vibrating beam accelerometer is a quartz resonator beam, and the working principle is that a mass block converts a measured acceleration into an inertial force acting on the resonator beam, changes the resonant frequency of the resonator beam, and utilizes a resonant circuit to detect the resonant frequency change and output a digital signal to the outside.

[0003] A traditional processing technology of the quartz vibrating beam accelerometer resonator is a wet etching process based on photoetching technology, and basic process steps mainly include: obtaining a quartz resonator beam pattern by using photoetching technology, and then etching a through groove on a quartz wafer by using wet etching. The method needs a special mask, the process is complex, and anisotropy of the traditional wet etching will cause uneven etching of the resonator beam, that is, side etching is prone to occur on the side wall and corner of the resonator beam, thereby affecting the performance of the resonator beam.

[0004] After the femtosecond laser is focused inside the quartz crystal, the structure of the irradiation area of the crystal is changed, and a modified area appears, and the etching rate of the modified area in the hydrofluoric acid solution is faster, and the characteristic can be used to realize the selective etching of the specific area. But the unirradiated area will still be etched by the hydrofluoric acid for a certain thickness, and the surface is easy to appear defects such as pitting. The present application combines the photolithography process and the femtosecond laser processing technology, adopts the chrome and gold film plated on the surface of the Z-cut alpha quartz wafer and etches the resonator pattern as the protection layer of the hydrofluoric acid etching process to prevent the thinning of the unmodified area and the generation of surface defects. The 800±20nm wavelength femtosecond laser is frequency doubled by the frequency doubling crystal (BBO) and filtered to obtain 400±5nm femtosecond laser, and the latter has a smaller ablation threshold for the alpha quartz crystal than the former, and has a smaller spot size after focusing. The Bessel beam has the characteristics of long focal depth and no diffraction. After the 400nm frequency doubled femtosecond laser is formed into a Bessel beam, the beam center radius is smaller than that of the original 800nm femtosecond laser, and the energy deposition efficiency is higher when it acts on the inside of the quartz crystal. Therefore, combined with the movement of the sample, the surface modification with large depth and high efficiency can be realized, and the modified surface penetrates through the upper and lower surfaces of the quartz wafer, and then the modified area is etched and removed by using the hydrofluoric acid solution, thereby realizing the etching and cutting of the quartz wafer. By controlling the movement of the precision three-dimensional electrically controlled translation stage, the frequency doubled Bessel beam is scanned and modified along the resonator pattern obtained by photolithography, and by using the subsequent etching of the hydrofluoric acid solution, the closed contour area is detached, and then the resonant beam array is left on the quartz wafer. SUMMARY

[0005] In order to solve the problems of side etching defects, poor uniformity of the side wall of the resonator and low yield rate of the product caused by the anisotropic etching characteristics of the traditional wet etching process of the quartz resonator of the existing quartz vibration beam accelerometer, the main purpose of the present application is to provide a method for selectively etching and processing the quartz vibration beam by using the frequency doubled Bessel laser, which can realize high-precision and high-side wall quality processing of the quartz vibration beam, effectively eliminate the side etching defects and improve the yield rate of the quartz vibration beam.

[0006] The purpose of the present application is achieved by the following technology.

[0007] The application discloses a quartz vibrating beam processing method based on selective etching of frequency-doubled Bessel laser, which utilizes chrome and gold films plated on the surface of a Z-cut alpha quartz wafer as a protective layer and realizes the property of selective etching of hydrofluoric acid after modification by frequency-doubled Bessel laser. First, 10-30 nm thick chrome (Cr) and 100-150 nm thick gold (Au) films are plated on both sides of the quartz wafer, then part of the metal film is etched away by using photoetching technology and plasma etching technology, and the area of the quartz crystal that needs to be etched is exposed, that is, a resonator pattern. Subsequently, a frequency-doubled crystal (BBO) is used to frequency-double the original wavelength 800±20 nm femtosecond laser into a frequency-doubled femtosecond laser with a central wavelength of 400 nm, a band-pass filter is used to filter the wavelength component of 400±5 nm, then the Gaussian-distributed femtosecond laser is spatially integrated into a non-diffractive Bessel beam with a long focal depth, and the Bessel beam after beam narrowing is focused inside the quartz wafer sample. By controlling the movement of the translation stage, the Bessel beam scans a modified surface that longitudinally penetrates the quartz wafer, and the scanning track is the resonator pattern profile formed after the plasma etching of the metal film. By using the characteristic that the etching rate of the modified area of the quartz wafer in the hydrofluoric acid solution is accelerated, selective etching of the specific modified area is realized, the etching surface penetrates the upper and lower surfaces of the quartz wafer, the sample in the closed profile part falls off after etching, and the required resonator array is left on the quartz wafer substrate, thereby realizing high-precision and high-sidewall quality processing of the quartz vibrating beam.

[0008] In order to ensure good adhesion between the gold film and the quartz substrate and the effect of plasma etching, preferably, 10 nm thick chrome (Cr) and 100 nm thick gold (Au) films are plated on both sides of the quartz wafer.

[0009] In order to ensure the uniformity of the frequency-doubled laser wavelength, preferably, after frequency-doubling the original wavelength 800±20 nm femtosecond laser, a band-pass filter with a wavelength of 400±5 nm is selected to filter the frequency-doubled femtosecond laser with a wavelength of 400±5 nm.

[0010] The quartz vibrating beam processing method based on selective etching of frequency-doubled Bessel laser disclosed by the application comprises the following steps:

[0011] Step one: 100-150 μm thick Z-cut alpha quartz wafer samples with a side length of 20-40 mm are ultrasonically cleaned with acetone, anhydrous ethanol and deionized water respectively, then the samples are blown dry by compressed air, and chrome film (Cr) and gold film (Au) are plated on both sides of the quartz wafer sample by using a magnetron sputtering film plating method.

[0012] Step two: respectively on the double side of the α-quartz wafer sample suspension coating photoresist, using double-sided lithography exposure, development technology respectively on the double side of the α-quartz wafer sample lithography photoresist resonator pattern; using the way of plasma etching to etch the gold (Au) and chromium (Cr) film layer exposed in the above photoresist resonator pattern, exposing the quartz substrate, to get the resonator pattern of removing gold chromium film layer;

[0013] Step three: build frequency-doubled Bessel beam femtosecond laser processing system, wherein the wavelength of 400±5nm femtosecond laser is generated by 800±20nm femtosecond laser through frequency-doubled crystal (BBO), get double wavelength mixed laser, and then filter out the 800nm wavelength component by using band-pass filter, get 400±5nm femtosecond laser; Bessel shaping device is composed of conical lens, plano-convex lens and focusing objective, Gaussian type femtosecond laser is shaped into Bessel beam after conical lens, plano-convex lens and focusing objective together constitute 4F beam-reducing system, further beam-reducing the Bessel beam shaped after conical lens;

[0014] Step four: fix the above Z-cut α-quartz wafer sample with gold chromium film layer resonator pattern on the precision three-dimensional electrically controlled translation stage, focus the frequency-doubled Bessel beam with wavelength of 400nm inside the quartz wafer, and make the Bessel beam scan along the contour of the above resonator pattern by controlling the movement of the translation stage, and the contour shape is the laser modified area;

[0015] Step five: ultrasonic cleaning the processed quartz wafer sample with acetone, ethanol and deionized water respectively, and blow dry with compressed air, then place in 5% hydrofluoric acid solution for etching, until the modified contour is etched completely, and the closed contour area falls off, leaving the quartz beam accelerometer resonator array on the quartz wafer sample.

[0016] As preferred, in step one, the Z-cut α-quartz wafer sample with thickness of 100μm and size of 20x20mm 2 is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water respectively; the composite metal film selects 10nm thick chromium film and 100nm thick gold film, the chromium film is an adhesion layer to increase the adhesion of the gold film to the quartz surface, and the gold film serves as a protective layer for subsequent hydrofluoric acid etching and as the final electrode of the quartz beam accelerometer resonator.

[0017] As preferred, the thickness of the suspended SU-8 photoresist in step two is 300nm, and the photoetching pattern and the gold film pattern etched by plasma are the resonator area to be removed.

[0018] As preferred, the motion trajectory of the translation stage in step four is the contour of the pattern in step two.

[0019] As preferred, the frequency-doubled Bessel beam femtosecond laser processing system of step three comprises a femtosecond laser, an attenuation piece group, an ultrafast mirror, a frequency-doubling crystal (BBO), a band-pass filter (400±5nm), a computer, a mechanical shutter, a conical lens, a plano-convex lens, a focusing objective, a dichroic mirror, a beam splitter, an illumination light source, a CCD imaging system, a precision three-dimensional electrically controlled translation stage, a manual pitch adjustment frame, and a quartz wafer. The femtosecond laser generates laser light, which is controlled by the attenuation piece group to control the size of the subsequent optical path laser energy. The wavelength 800±20nm femtosecond laser is frequency-doubled by the frequency-doubling crystal (BBO) to obtain 400nm and 800nm mixed frequency laser, which is then filtered by the band-pass filter to obtain the wavelength 400±5nm frequency-doubled femtosecond laser. The ultrafast mirror controls the light path direction, and the mechanical shutter controls the on-off of the light path. After the laser passes through the conical lens, the Gaussian beam is reshaped into a Bessel beam. After passing through the 4f beam-reducing system composed of the plano-convex lens and the focusing objective, the Bessel beam is beam-reduced to improve its energy density, and is finally focused inside the quartz wafer sample. The sample is fixed on the manual pitch adjustment frame, which can be used to adjust the level of the sample surface, so that the laser focus point is always located on the sample surface during the processing. The white light source is placed above the dichroic mirror, and the white light transmits through the dichroic mirror to irradiate on the sample surface. The reflected light of the sample surface is reflected into the CCD imaging system after passing through the focusing objective, the dichroic mirror and the beam splitter, realizing real-time detection of the sample processing process, and ensuring the yield of the quartz vibrating beam.

[0020] As preferred, the 400nm frequency-doubled light generating device of step three comprises a barium borate frequency-doubling crystal (BBO) and a band-pass filter (center wavelength 400nm, band-pass range 10nm).

[0021] As preferred, the Bessel beam shaping device of step three comprises a conical lens with a base angle of 2°, a plano-convex lens with a focal length of 100mm, and a 50x focusing objective.

[0022] As preferred, the processing parameters of step four are used to realize effective modification of the quartz wafer by the frequency-doubled Bessel beam, ensure the processing precision of the vibrating beam profile, realize effective etching in the hydrofluoric acid solution, ensure that the etching surface penetrates the quartz wafer, ensure the uniformity of the modification, the surface quality of the vibrating beam side wall after etching, and avoid the occurrence of micro-cracks around the modified area caused by over-modification.

[0023] As preferred, the femtosecond laser frequency-doubled Bessel beam processing parameters are: pulse energy 6-8μJ, laser center wavelength 400nm, pulse delay 35fs, scanning speed 100-200μm / s, and the defocusing amount of the Bessel beam light field center relative to the upper surface of the quartz wafer is 50-90μm.

[0024] As preferred, the etchant in step five is a 5% hydrofluoric acid solution, and the etching condition is 10 hours at room temperature.

[0025] Advantages

[0026] 1. A quartz vibrating beam processing method based on frequency-doubled Bessel laser selective etching, which uses chromium film (Cr) and gold film (Au) as protective layers to protect the laser-unprocessed surface of alpha quartz crystal from being etched by hydrofluoric acid when the quartz crystal is etched in a hydrofluoric acid solution, maintain high surface quality of the quartz wafer sample, and avoid thinning of the overall thickness of the sample.

[0027] 2. A quartz vibrating beam processing method based on frequency-doubled Bessel laser selective etching, which uses a frequency-doubling crystal (BBO) to frequency-double a femtosecond laser with a wavelength of 800±20 nm to obtain a 400±5 nm femtosecond laser, which has a lower modification threshold, higher energy deposition efficiency, and smaller focused central light field diameter when interacting with the quartz crystal, and can achieve efficient processing with sub-micron size precision.

[0028] 3. A quartz vibrating beam processing method based on frequency-doubled Bessel laser selective etching, which uses a femtosecond laser-assisted selective etching method to essentially solve the side etching caused by the anisotropy of traditional wet etching, and the defects such as convex edges on the sidewall, and the processed resonant beam has good sidewall uniformity and high surface quality. The frequency-doubled Bessel laser has a smaller central light field diameter than the original 800 nm Bessel laser, but the Bessel focal depth remains unchanged, the depth-to-diameter ratio of the laser irradiation area is larger, and the processing precision is higher.

[0029] 4. A quartz vibrating beam processing method based on frequency-doubled Bessel laser selective etching, which can adjust the processing trajectory by controlling the movement of a three-dimensional electrically controlled translation stage through a computer, and can realize flexible adjustment of the size profile of the vibrating beam. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 A flowchart of a quartz vibrating beam processing method based on frequency-doubled Bessel laser selective etching according to the present application;

[0031] Figure 2 A process schematic diagram of a quartz vibrating beam processing method based on frequency-doubled Bessel laser selective etching according to the present application;

[0032] Figure 3 A schematic diagram of the changes in the quartz wafer sample cross-section and chromium film and gold film during the processing of a quartz vibrating beam processing method based on frequency-doubled Bessel laser selective etching according to the present application;

[0033] Figure 4 A schematic diagram of the optical path of a frequency-doubled Bessel beam femtosecond laser processing system.

[0034] Figure 5 Fig. 1 is a normalized intensity distribution diagram along the radial direction and a light field distribution diagram along the propagation direction of a Bessel light beam with a wavelength of 400 nm and a wavelength of 800 nm;

[0035] Figure 6 Fig. 2 is an optical microscopic imaging diagram of a processed quartz resonator accelerometer resonator;

[0036] Figure 7 Fig. 3 is a scanning electron microscope imaging diagram of a resonator beam side wall;

[0037] Wherein: 1-femtosecond laser, 2-decay piece group, 3-ultrafast mirror, 4-frequency doubling crystal (BBO), 5-band pass filter, 6-computer, 7-mechanical shutter, 8-conical lens, 9-flat convex objective, 10-focusing objective, 11-dichroic mirror, 12-beam splitter, 13-illumination light source, 14-CCD imaging system, 15-precision three-dimensional electric control translation stage, 16-manual pitch adjustment frame, 17-quartz wafer. DETAILED DESCRIPTION

[0038] The application will be further described below in combination with the drawings and examples.

[0039] EXAMPLE

[0040] As shown in the figure, the embodiment discloses a quartz resonator beam processing method based on frequency-doubled Bessel laser selective etching, and the specific steps are as follows: Figure 1 In the experimental processing process, the femtosecond laser parameters used are as follows: the initial femtosecond laser wavelength is 800±20 nm, the frequency-doubled and filtered laser wavelength is 400±5 nm, the pulse width is 35 fs, the pulse repetition frequency is 1 kHz, the polarization state is linear polarization, and the focal depth length of the frequency-doubled Bessel light beam after beam shrinking and focusing is about 220 μm. The processed sample is a 100 μm thick, 20x20 mm 2 double-side polished Z-cut quartz wafer.

[0041] Step 1: A Z-cut alpha quartz wafer sample with a thickness of 100 μm and a size of 20x20 mm 2 is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water respectively, and then the sample is blown dry by compressed air. A 10 nm thick chromium film (Cr) and a 100 nm thick gold film (Au) are successively plated on the double sides of the quartz wafer sample by means of magnetron sputtering film plating;

[0042]

[0043] ​Step two: 300nm thickness SU-8 photoresist is suspendedly coated on both sides of the alpha quartz wafer sample respectively, and photoresist resonator patterns are photoetched on both sides of the alpha quartz wafer sample respectively by using double-sided photoetching and developing technology; the gold (Au) and chromium (Cr) film layers exposed in the above photoresist resonator patterns are etched away by using plasma etching, so that the quartz substrate is exposed, and a resonator pattern with gold and chromium film layers removed is obtained;

[0044] Step three: a frequency-doubled Bessel beam femtosecond laser processing system is built, including a femtosecond laser 1, an attenuation piece group 2, an ultrafast mirror 3, a frequency-doubling crystal 4 (BBO), a band-pass filter 5, a computer 6, a mechanical shutter 7, a conical lens 8, a plano-convex lens 9, a focusing objective lens 10, a dichroic mirror 11, a beam splitter 12, an illumination light source 13, a CCD imaging system 14, a precision three-dimensional electric control translation stage 15, a manual pitch adjustment frame 16, and a quartz wafer 17. The wavelength of the femtosecond laser generated by the femtosecond laser 1 is 800±20nm. After frequency doubling by the frequency-doubling crystal (BBO), 800nm and 400nm dual-wavelength mixed laser is obtained. Then the 800nm wavelength component is filtered out by the band-pass filter, and the wavelength of the femtosecond laser is 400±5nm. The size of the laser energy incident to the frequency-doubling crystal is controlled by the attenuation piece group 2, thereby controlling the energy size of the frequency-doubled 400nm femtosecond laser. The light path is controlled by the ultrafast mirror 3. The on-off of the light path is controlled by the mechanical shutter 7. The laser energy is controlled by the attenuation piece group 2 in the light path. After the 400nm wavelength frequency-doubled laser energy is adjusted to a preset value, it enters the conical lens 8. The Gaussian beam is formed into a Bessel beam. After passing through the 4f beam-reducing system composed of the plano-convex lens 9 and the focusing objective lens 10, the Bessel beam is beam-reduced to improve its energy density, and is finally focused inside the quartz wafer sample 17. The sample is fixed on the manual pitch adjustment frame 16. The horizontal of the sample surface can be adjusted by using the adjustment frame, so that the laser focal point is always located on the sample surface during the processing. The white light source 13 is placed above the beam splitter 12. The white light passes through the beam splitter 12 and the dichroic mirror 11 and then irradiates on the sample surface. The reflected light of the sample surface is reflected into the CCD imaging system 14 after passing through the focusing objective lens 10, the dichroic mirror 11 and the beam splitter 12, so as to realize real-time detection of the sample processing process.

[0045] Step four: the quartz crystal wafer sample with the quartz vibration beam accelerometer resonator pattern is fixed on a precision three-dimensional electrically controlled translation stage, a frequency-doubled Bessel beam is focused inside the quartz wafer, a pre-generated resonator pattern contour trajectory numerical control code file is run through computer control software, the precision three-dimensional electrically controlled translation stage is controlled to move along the gold film resonator pattern contour, the movement speed of the translation stage is set to be in the range of 100-200 μm / s, the energy of the femtosecond laser pulse is adjusted to be between 8-10 μJ by using the attenuation piece group, the defocusing amount of the Bessel beam center relative to the upper surface of the quartz wafer is set to be 50-90 μm, and the Bessel beam scans the resonator contour shape in the quartz wafer, that is, the laser modification area.

[0046] Step five: the processed quartz wafer sample is ultrasonically cleaned with acetone, ethanol and deionized water respectively, and is blown dry with compressed air, and is then placed in a 5% hydrogen fluoride acid solution for etching until the modification contour is etched completely, that is, the quartz material on both sides of the contour is separated, the closed contour area is detached, and then the resonator beam array is left on the quartz wafer sample.

[0047] Step six: the sidewall of the quartz resonator beam is scanned and imaged by a scanning electron microscope, as shown in FIG. 6. Figure 7 As shown in the results, the processed resonator beam processing surface, that is, the sidewall has good uniformity, low surface roughness, no side etching ridge structure, and high yield.

[0048] As can be seen from the embodiment of the present application, the chromium film and gold film as the protective layer can effectively avoid the unprocessed area of the alpha quartz wafer from being etched by the hydrogen fluoride acid solution, and maintain the high quality of the surface. Secondly, the method of modifying and assisting chemical etching by using the frequency-doubled femtosecond laser Bessel beam to process the quartz vibration beam resonator can fully utilize the advantages of lower modification threshold and higher energy deposition efficiency of the frequency-doubled femtosecond laser on the quartz crystal, and higher processing precision. Compared with the traditional wet etching process, the resonator beam processed by the method does not have the side etching and the side wall with ridges that are prone to occur in the traditional etching process, and has high sidewall surface quality and good uniformity.

[0049] The above specific description further details the purpose, technical solution and beneficial effects of the present application, and it should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for processing quartz vibrating beams based on selective etching using frequency-doubled Bessel lasers, characterized in that, Includes the following steps: Step 1: The Z-cut α-quartz wafer samples with a thickness of 100-150μm and a side length of 20-40mm were ultrasonically cleaned with acetone, anhydrous ethanol and deionized water respectively. Then, the samples were dried with compressed air. Chromium film and gold film were deposited on both sides of the quartz wafer sample by magnetron sputtering. Step 2: Photoresist is coated on both sides of the α-quartz wafer sample, and photoresist resonator patterns are etched on both sides of the α-quartz wafer sample using double-sided photolithography exposure and development technology. The gold and chromium film layers exposed in the above photoresist resonator pattern are etched away using plasma etching to expose the quartz substrate, resulting in a resonator pattern with the gold and chromium film layers removed. Step 3: Construct a frequency-doubled Bessel beam femtosecond laser processing system. The femtosecond laser with a wavelength of 400±5nm is generated by frequency doubling an 800±20nm femtosecond laser using a frequency doubling crystal to obtain a dual-wavelength mixed laser. Then, a bandpass filter is used to filter out the 800nm ​​wavelength component to obtain the 400±5nm femtosecond laser. The Bessel beam shaping device includes a conical lens with a base angle of 2°, a plano-convex lens with a focal length of 100mm, and a 50x focusing objective. Gaussian femtosecond lasers are shaped into Bessel beams after passing through a conical lens. The plano-convex lens and the focusing objective lens together form a 4F beam-shrinking system, which further shrinks the Bessel beam shaped by the conical lens. Step 4: Fix the Z-cut α-quartz wafer sample with the gold-chromium film resonator pattern onto a precision three-dimensional electrically controlled translation stage. Focus a frequency-doubled Bessel beam with a wavelength of 400nm into the interior of the quartz wafer. By controlling the movement of the translation stage, the Bessel beam scans and processes along the contour of the resonator pattern. The contour shape is the laser-modified area. Step 5: The processed quartz wafer sample is ultrasonically cleaned with acetone, ethanol and deionized water respectively, and dried with compressed air. Then it is placed in a 5% hydrofluoric acid solution for full etching until the modified contour is completely etched and the closed contour area falls off, leaving a quartz vibrating beam accelerometer resonator array on the quartz wafer sample. The Bessel beam processing parameters are as follows: pulse energy of 6-8 μJ, laser center wavelength of 400 nm, pulse delay of 35 fs, scanning speed of 100-200 μm / s, and defocusing of the Bessel beam center relative to the upper surface of the quartz wafer of 50-90 μm.

2. The method for processing quartz vibrating beams based on frequency-doubled Bessel laser selective etching as described in claim 1, characterized in that: In step one, the chromium film plated on both sides of the quartz wafer is 10nm thick, and the gold film is 100nm thick, serving as a protective layer for hydrofluoric acid etching.

3. The method for processing quartz vibrating beams based on frequency-doubled Bessel laser selective etching as described in claim 1, characterized in that: In step two, the photolithography process uses a resonator pattern as the mask pattern, i.e., the exposure area. The photoresist used is SU-8 photoresist. The plasma etching process removes the chromium and gold films in the photolithography exposure area, exposing the quartz substrate.

4. The method for processing quartz resonant beams based on frequency-doubled Bessel laser selective etching as described in claim 1, characterized in that: In step three, the focal depth of the Bessel beam, which is the focal length of the plano-convex lens, is 180–220 μm after being focused by the 4F beam-contraction system.

5. The method for processing quartz vibrating beams based on frequency-doubled Bessel laser selective etching as described in claim 1, characterized in that: In step four, the Bessel beam needs to be selected with appropriate laser output power and repetition frequency. The repetition frequency is 1kHz and the laser output power is selected as 7-9mW.

6. The method for processing quartz vibrating beams based on frequency-doubled Bessel laser selective etching as described in claim 1, characterized in that: In step five, the etching time of the processed quartz wafer in hydrofluoric acid is 10 hours.

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