CN115178892A - High-quality cutting method for millimeter-thickness quartz glass - Google Patents

Abstract

The invention provides a high-quality cutting method of millimeter-thickness quartz glass, which fully utilizes the characteristics that femtosecond laser can break through the extremely small range of a specified position of a diffraction limit to carry out high-precision processing, has high spatial resolution and the like, mainly adopts a femtosecond laser feeding mode, laser power, scanning speed and single feeding amount by controlling laser flux and focusing conditions, applies the femtosecond laser with optimized process parameters to carry out modification processing on the quartz glass, and combines ultrasonic wave auxiliary HF chemical solution to carry out selective etching on a modified sample to realize high-quality cutting on the millimeter-thickness quartz glass. The method is suitable for cutting the quartz glass with the thickness of less than or equal to 1000 micrometers, so that the straightness of a processed sample can reach more than 89 degrees and is close to an ideal angle, the edge breakage size is less than 2 micrometers, the section roughness is less than 0.5 micrometer, the cutting method has certain applicability and repeatability, and the consistency of the processing quality can be ensured.

Description

A high-quality cutting method for millimeter-thick quartz glass

technical field

The invention belongs to the field of micromachining, in particular to a method for cutting fused silica glass with a thickness of millimeters.

Background technique

As a material with outstanding comprehensive properties, quartz glass has been widely used in many industrial fields due to its good physical and chemical properties. As a transparent material, its excellent light transmission makes it commonly used in the lighting and optical components industries; the temperature stability and excellent radiation resistance of quartz glass make it play an important role in the aerospace industry; The industries with large demand for glass are the semiconductor industry and the optical fiber communication industry, which are mainly used as key auxiliary materials. Due to its low thermal expansion coefficient, low internal damping loss and good mechanical properties, quartz glass can be used as a precision elastic material, and is gradually used in the manufacture of flexible accelerometers, resonant gyroscopes and other core components in inertial navigation systems . And with the continuous development of microelectromechanical systems (MEMS), quartz glass has broad application prospects in the field of microelectronic devices, so its application in the processing and manufacturing of microdevices has attracted the attention of many scientific research institutions.

In order to meet the requirements of the actual project, the integrally formed quartz glass blank needs to be processed into a specific shape, especially the resonator in the vibrating gyroscope with the sensitivity amplification structure, and the high three-dimensional symmetry of the core device needs to be ensured, and the quality of the cutting process will be It directly determines the upper limit of the performance of the gyro. At the same time, due to the high brittleness and low fracture strength of quartz glass, it is necessary to adopt suitable processing methods to ensure the surface integrity and structural reliability of the device. The common technologies for cutting quartz glass mainly include: diamond grinding wheel grinding, abrasive water jet processing, plasma etching, femtosecond laser direct ablation and so on. However, the cutting quality of diamond grinding wheel and abrasive water jet cutting fused silica is low, and the roughness of the cutting section cannot meet the requirements of high-precision machining; ion beam etching quartz can obtain high roughness, but it is difficult to ensure the steepness of the cutting section. Straightness; some other methods are inflexible and complicated to operate, and are not suitable for cutting quartz glass into complex shapes. In contrast, femtosecond laser direct ablation has certain applicability to the cutting of quartz glass and can ensure high precision. Because femtosecond laser is an ultra-short pulse width laser, it can realize "cold processing" of hard and brittle transparent media. However, it is inevitable that different application scenarios have different requirements for the thickness of the quartz substrate. The existing femtosecond laser direct ablation cutting mainly focuses on the quartz glass with a thickness of about 200 microns, while the high-quality samples for larger thickness samples Fewer cutting solutions. Therefore, it is urgent to solve the problem of realizing high-quality cutting process of quartz glass with a thickness of millimeters.

SUMMARY OF THE INVENTION

(1) Technical problems to be solved

The purpose of the present invention is to provide a high-quality cutting method for quartz glass with a thickness of millimeters, which makes full use of the femtosecond laser beam to form a Gaussian distribution, can be focused to any position inside the material through a transparent medium, and realizes a very small laser focusing area. The interaction with the material, that is, high-precision processing at the specified position that breaks through the diffraction limit, and has the characteristics of high spatial resolution. By controlling the laser flux and focusing conditions, the femtosecond laser is used to modify the quartz glass, and then Combined with ultrasonic-assisted HF chemical solution for selective etching of modified samples, high-quality cutting of millimeter-thick quartz glass can be achieved, so that the steepness of the sample after processing can reach more than 89°, and the edge chipping size is less than 2μm , the section roughness is less than 0.5μm, the cutting method has certain applicability, repeatability, and can ensure the consistency of processing quality.

(2) Technical solutions

The present invention is achieved through the following technical solutions:

The invention relates to a high-precision cutting method for millimeter-thick quartz glass, which is suitable for cutting quartz glass with a thickness of less than or equal to 1000 μm. By controlling the femtosecond laser to modify the processing parameters of quartz glass, mainly the femtosecond laser feeding method, laser power, scanning speed and single feeding amount, and then combined with ultrasonic assisted HF solution to etch the sample, and then realize High-quality cutting of quartz glass with a thickness of 1000 μm and below.

A high-precision cutting method for millimeter-thick quartz glass, comprising the following steps:

Step 1: Build a femtosecond laser processing system. The whole system is mainly composed of femtosecond laser, host computer, diaphragm, mirror, optical gate, objective lens, three-dimensional motion platform and CCD camera. From the laser, the femtosecond laser passes through a diaphragm, three mirrors, and an optical gate in sequence, and finally passes through the objective lens to focus vertically on the sample. During processing, the optical path of the femtosecond laser remains unchanged, and the sample is processed by moving the quartz glass and the laser focus relative to the moving platform. The femtosecond laser, optical gate and three-dimensional motion platform all establish communication with the host computer, and can control and adjust parameters in the host computer. After the system is built, the optical path is collimated.

Step 2: Quartz glass sample pretreatment. In order to ensure the cleanliness of the quartz glass surface and avoid dust and other interference with the interaction between the femtosecond laser and the sample. Put the quartz glass in pure water and absolute ethanol for sufficient time with an ultrasonic cleaner, and then dry it with nitrogen. Then place the clean sample on the stage of the processing system in step 1 to complete the sample clamping.

Step 3: Quartz glass and femtosecond laser focus positioning. Under the condition of sufficient lighting, adjusting the field of view and focal length of the CCD camera can clearly observe the images collected from the quartz glass; increase the laser energy of the femtosecond laser through the upper computer, and the laser beam is focused by the objective lens to form air ionization The CCD camera can collect the spot image of the air ionization spot, and the center of the spot is the femtosecond laser focus. The position of the sample and the laser focus can be observed and determined according to the image collected by the camera, and the moving platform is controlled to move the sample to a suitable position and set as the starting point of laser processing.

Step 4: Set the processing parameters and program the processing path. By controlling the three-dimensional motion platform to move the quartz glass and the femtosecond laser relative to each other, and adjusting the feed mode, femtosecond laser power, scanning speed and single feed amount, the optimal parameters for the modification of the femtosecond laser on the quartz glass are obtained. : The bottom-up feeding method is adopted, the laser power is 20mW, the scanning speed is 400μm/s, and the single feeding amount is 10μm. Combined with the processing parameters, the cutting path of the quartz glass is converted into the combined motion of the three-dimensional motion platform, and it is programmed and integrated into the control software of the upper computer. The modification processing of quartz glass by femtosecond laser can be completed by executing the program.

Step 5: Ultrasonic-assisted chemical etching. Put the femtosecond laser-modified quartz glass in step 4 in a container with a certain concentration of HF solution, place the container in an ultrasonic cleaner, set appropriate parameters and turn it on, after a certain period of time, that is, Quartz glass can be cut.

Step 6: Quartz glass post-processing after cutting. The cut and broken quartz glass samples were placed in pure water and absolute ethanol for sufficient time with an ultrasonic cleaner, and then dried with nitrogen. Select special equipment to measure the relevant indicators of the cleaned samples to characterize the cutting quality.

(3) Beneficial effects

The above-mentioned technical scheme of the present invention has the following advantages:

(1) The present invention utilizes the characteristics that the femtosecond laser beam can pass through the transparent medium and act at any position inside the material, the action range can be controlled in a very small focus area, and the spatial resolution is high. Based on the three-dimensional high-precision motion platform, the The bottom-up feeding method is used to modify the quartz glass, which can be applied to quartz glass with a large thickness range, and has certain applicability and repeatability.

(2) The present invention realizes the modification processing of quartz glass by adjusting the femtosecond laser power, scanning speed and single feed amount to change the laser flux and focusing conditions, and then combined with ultrasonic-assisted HF solution to select the modified quartz glass The method of etching is used to realize the cutting of quartz glass, which can make the steepness of the processed sample close to the ideal angle, the edge chipping size and section roughness are small, and the consistency of the processing quality can be ensured.

(3) The CCD camera is used as the imaging module in the processing system built in the present invention, which facilitates observation and determination of the positions of the quartz glass and the femtosecond laser focus, ensures the accuracy of the processing starting point, and at the same time prevents the operator from looking directly at the laser. certain security protection. And by controlling the three-dimensional motion platform to realize processing, the processing path can be programmed, and the operation is convenient.

Description of drawings

The features and advantages of the present invention will be more clearly understood by reference to the accompanying drawings, which are schematic and should not be construed as limiting the invention in any way, in which:

Fig. 1 is the basic principle diagram of the quartz glass cutting method provided in the embodiment of the present invention;

2 is a schematic diagram of a femtosecond laser processing system provided in an embodiment of the present invention;

Fig. 3 measures the steepness of cutting quartz glass by the ultra-depth-of-field microscope provided in the embodiment of the present invention;

Fig. 4 is the edge chipping of the ultra-depth-of-field microscope provided in the embodiment of the present invention to measure and cut quartz glass;

FIG. 5 shows the optical profiler provided in the embodiment of the present invention measuring the section roughness of the cut quartz glass.

illustration:

1: femtosecond laser; 2: diaphragm; 3: mirror; 4: mirror; 5: mirror; 6: light gate; 7: objective lens; 8: 3D motion platform; 9: CCD camera; 10: controller ;11: Host computer.

Detailed ways

The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments. The following examples are intended to illustrate the present invention, but not to limit the scope of the present invention.

As shown in Figure 1, a high-quality cutting method of millimeter-thick quartz glass, this method is suitable for the cutting of quartz glass with a thickness of ≤ 1000 μm. The basic principle is to control the femtosecond laser flux and scan the quartz glass according to the cutting path to complete the modification process, and then combine the ultrasonic-assisted HF solution to selectively chemically etch the modified quartz glass to achieve High quality cutting of quartz glass.

A high-quality cutting method for millimeter-thick quartz glass, comprising the following steps:

Step 1: Build a femtosecond laser processing system. The overall processing system is shown in Figure 2. The femtosecond laser uses a high repetition frequency femtosecond laser, the laser wavelength is 1030nm, the repetition frequency is adjustable from 1kHz to 1MHz, and the pulse width is 235fs. The maximum output power of the beam is 2.06W. The optical path arrangement is realized by diaphragm, three mirrors, and optical gate, which can make full use of the experimental space, and adjust the diaphragm and mirror to collimate the femtosecond laser, and the optical gate can control the on-off of the optical path. The femtosecond laser beam can be focused on the sample through a 10X (NA=0.25) objective lens, and the sample is clamped on the stage of the three-dimensional linear motion platform, and the motion accuracy of the platform can reach 0.1μm. Make relative motion to realize processing. The CCD camera plays the role of auxiliary positioning and observation. Among them, the high repetition frequency femtosecond laser, optical gate, three-dimensional motion platform and CCD camera all establish communication with the host computer, and can operate and control several core equipment in the host computer.

Step 2: Quartz glass pretreatment. The quartz glass used is fused silica glass, the content of SiO ₂ is 99.99%, the upper and lower surfaces are squares with side lengths of 10 mm, and the thickness is less than or equal to 1000 μm. Put the fused silica glass in pure water and anhydrous ethanol for 5 minutes with an ultrasonic cleaner, then dry the cleaned samples with nitrogen with a concentration of 99.9%, and then clamp the clean samples in the processing system in step 1. Adhesives are mainly used for bonding on the stage.

Step 3: Quartz glass and femtosecond laser focus positioning. Here, halogen lamps are used to provide sufficient illumination, and the field of view and focal length of the CCD camera can be adjusted, so that the images collected from the fused silica glass can be clearly observed; through the software in the host computer, the energy of the femtosecond laser emitted by the femtosecond laser is adjusted to be larger, and the laser beam After being focused by the objective lens, an air ionization spot is formed, and the CCD camera can collect the spot image of the air ionization spot, and the center of the spot is the femtosecond laser focus. The position of the fused silica glass and the laser focus can be observed and determined according to the image collected by the camera, and the moving platform is controlled to move with the fused silica glass, so that the femtosecond laser focus moves relatively to a position 10 μm away from the lower surface of the sample, and set It is the starting point of laser processing.

Step 4: Set the processing parameters and program the processing path. By controlling the three-dimensional motion platform to move the quartz glass and the femtosecond laser relatively, and adjusting the femtosecond laser feed mode, femtosecond laser power, scanning speed and single feed amount in the host computer, the femtosecond laser to quartz is obtained. The best parameters for glass modification processing: the bottom-up feeding method is adopted, the laser power is 20mW, the scanning speed is 400μm/s, and the single feed is 10μm. Combined with the processing parameters, the cutting path of the fused silica glass is converted into the combined motion of the three-dimensional motion platform, and it is programmed and integrated into the control software of the upper computer by using the C++ high-level programming language. The modification processing of quartz glass by femtosecond laser can be completed by executing the program.

Step 5: Ultrasonic-assisted chemical etching. Put the femtosecond laser-modified quartz glass in step 4 in a container with a 5% concentration of HF solution, place the container in an ultrasonic cleaner, set the ultrasonic power to 80W, and the ultrasonic frequency to 40kHz, after 10min After the ultrasonic-assisted chemical etching of time, the cutting of the quartz glass can be completed.

Step 6: Quartz glass post-processing after cutting. The cut fused silica glass samples were placed in pure water and absolute ethanol for 5 min with an ultrasonic cleaner, and then dried with nitrogen. Select special equipment to measure the relevant indicators of the cleaned samples to characterize the cutting quality. For the fused silica glass with a thickness of 1000 μm after cutting, the edge chipping size and the section steepness of the fused silica glass with a thickness of 1000 μm were measured using a super-depth-of-field microscope. The results are shown in Figures 3 and 4 below; The profiler was characterized, and the results are shown in Figure 5 below. The above processing parameters and methods were used to cut fused silica glass with a thickness of 300 μm and 1000 μm, and the comparison results of the measured related quality indicators are shown in Table 1 below.

Table 1: 300 μm and 1000 μm Thickness Fused Silica Glass Cut Quality

Sample thickness/μm Steepness/° Edge chipping size/μm Section Roughness/nm 300 89.6 1.6 326.833 1000 89.7 1.8 497.569

The beneficial effects of this embodiment are as follows: as shown in the table above, by applying the cutting method and process parameters for quartz glass proposed by the present invention, the cutting of fused silica glass with a thickness of 300 μm and 1000 μm can be realized, and the complete cutting can be ensured without the need for The subsequent operation of mechanical force application reduces the stress concentration after the sample is cut, and can ensure the cutting quality, the steepness can reach an ideal 90°, the edge chipping size can also be less than 2μm, and the section roughness can be less than 0.5 μm, this process combines femtosecond laser modification processing of transparent media with chemical solution selective etching technology, by controlling femtosecond laser power, feed mode, scanning speed and single feed amount of several processing parameters , realizes high-quality cutting of millimeter-thick quartz glass, has certain applicability and repeatability, can be used in the field of micromachining, and has broad application prospects in the manufacture of microdevices.

Claims (3)

1. A high-quality cutting method for millimeter-thickness quartz glass is characterized in that a femtosecond laser feeding mode, laser power, scanning speed and single feeding amount are mainly used for controlling laser flux and focusing conditions, femtosecond laser with optimized technological parameters is used for modifying and processing the quartz glass, and then ultrasonic wave is combined with an HF chemical solution for assisting selective etching of a modified sample, so that high-quality cutting for millimeter-thickness quartz glass is realized.

2. A method for high-quality cutting of quartz glass of millimeter thickness, characterized in that it comprises the following steps:

step 1: and (5) constructing a femtosecond laser processing system. The whole system mainly comprises a femtosecond laser, an upper computer, a diaphragm, a reflector, an optical gate, an objective lens, a three-dimensional motion platform and a CCD camera. The femtosecond laser from the laser passes through the diaphragm, the three reflectors, the optical gate in turn and is vertically focused on the sample through the objective lens. The femtosecond laser, the light gate and the three-dimensional motion platform are communicated with an upper computer, and parameters can be controlled and adjusted in the upper computer. After the system is built, light path collimation is carried out.

Step 2: and (4) pretreating a quartz glass sample. The quartz glass is respectively put in pure water and absolute ethyl alcohol, cleaned for enough time by an ultrasonic cleaner and then dried by nitrogen. And then, placing the clean sample on an object stage of the processing system in the step 1 to finish sample clamping.

And 3, step 3: quartz glass and femtosecond laser focus positioning. Under the condition of giving sufficient illumination, the field of view and the focal length of the CCD camera are adjusted, and the image of the quartz glass can be clearly observed and collected; the energy of the laser emitted by the femtosecond laser is increased through the upper computer, the laser beam forms an air ionization point after being focused by the objective lens, the CCD camera can acquire a light spot image of the air ionization point, and the center of the light spot is the femtosecond laser focus. And observing and determining the positions of the sample and the laser focus according to the image acquired by the camera, controlling the motion platform to drive the sample to move to a proper position, and setting the position as a laser processing starting point.

And 4, step 4: and setting processing parameters and programming a processing path. The method comprises the following steps of controlling a three-dimensional motion platform to drive quartz glass and femtosecond laser to make relative motion, and adjusting a feeding mode, femtosecond laser power, scanning speed and single feeding amount to obtain optimal parameters of the femtosecond laser for quartz glass modification processing: the feeding mode from bottom to top is adopted, the laser power is 20mW, the scanning speed is 400 mu m/s, and the single feeding amount is 10 mu m. And converting the cutting path of the quartz glass into the combined motion of the three-dimensional motion platform by combining the processing parameters, and integrating the cutting path of the quartz glass into the control software of the upper computer in a programming manner. And executing the program to finish the modification processing of the femtosecond laser to the quartz glass.

And 5: and (4) carrying out ultrasonic-assisted chemical etching. And (4) placing the quartz glass modified by the femtosecond laser in the step (4) into a container filled with HF solution with a certain concentration, placing the container into an ultrasonic cleaning machine, setting appropriate parameters, starting the container, and finishing cutting of the quartz glass after a certain time.

Step 6: and (5) performing aftertreatment on the cut quartz glass. And respectively putting the cut quartz glass samples into pure water and absolute ethyl alcohol, cleaning the quartz glass samples for enough time by using an ultrasonic cleaning machine, and then drying the quartz glass samples by using nitrogen. And measuring related indexes of the cleaned sample by using special equipment to represent cutting quality.

3. A method for high quality cutting of quartz glass of millimeter thickness according to claim 2, characterized in that it is embodied in such a way that it comprises the following steps:

step 1: and (5) constructing a femtosecond laser processing system. The femtosecond laser device adopts a high repetition frequency femtosecond laser device, the laser wavelength is 1030nm, the repetition frequency is 1 kHz-1 MHz and is adjustable, the pulse width is 235fs, the repetition frequency of the femtosecond laser device is 10kHz, and the maximum output power of a laser beam is 2.06W. The light path arrangement is realized through a diaphragm, three reflectors and a light gate, the experimental space can be fully utilized, the diaphragm and the reflectors are adjusted to collimate the femtosecond laser, and the on-off of the light path can be controlled by the light gate. The femtosecond laser beam can be focused on a sample through a 10X (NA = 0.25) objective lens, the sample is clamped on an object stage of a three-dimensional linear motion platform, the motion precision of the platform can reach 0.1 mu m, and the motion platform bears the sample and makes relative motion with the femtosecond laser focus, so that the processing is realized. The CCD camera plays a role in auxiliary positioning and observation. The high repetition frequency femtosecond laser, the light gate, the three-dimensional motion platform and the CCD camera are communicated with an upper computer, and several core devices can be operated and controlled in the upper computer.

Step 2: and (4) pretreating quartz glass. The quartz glass is fused quartz glass, siO ₂ 99.99 percent of quartz glass substrate sample, the upper and lower surfaces of which are squares with 10mm side length and the thickness of which is less than or equal to 1000 mu m. Respectively putting fused quartz glass in pure water and absolute ethyl alcohol, cleaning for 5min by using an ultrasonic cleaning machine, then blowing the cleaned sample by using nitrogen with the concentration of 99.9%, and clamping the cleaned sample on an objective table of the processing system in the step 1, wherein the adhesion is mainly carried out by adopting an adhesive.

And step 3: quartz glass and femtosecond laser focus positioning. The halogen lamp is used for providing sufficient illumination, the visual field and the focal length of the CCD camera are adjusted, and the image of the fused quartz glass can be clearly observed and collected; the energy of laser emitted by the femtosecond laser is adjusted to be larger through software in the upper computer, the laser beam forms an air ionization point after being focused by the objective lens, the CCD camera can acquire a light spot image of the air ionization point, and the center of the light spot is the femtosecond laser focus. Namely, the positions of the fused silica glass and the laser focus can be observed and determined according to the image collected by the camera, and the motion platform is controlled to drive the fused silica glass to move, so that the femtosecond laser focus relatively moves to a position 10 mu m away from the lower surface of the lower sample and is set as a laser processing starting point.

And 4, step 4: and setting processing parameters and programming a processing path. The method comprises the following steps of controlling a three-dimensional motion platform to drive quartz glass and femtosecond laser to make relative motion, and adjusting a femtosecond laser feeding mode, femtosecond laser power, scanning speed and single feeding amount in an upper computer to obtain optimal parameters of the femtosecond laser for quartz glass modification processing: the feeding mode from bottom to top is adopted, the laser power is 20mW, the scanning speed is 400 mu m/s, and the single feeding amount is 10 mu m. And converting the cutting path of the fused quartz glass into combined motion of a three-dimensional motion platform by combining with the processing parameters, and integrating the combined motion into control software of an upper computer by programming by using a C + + high-level programming language. And the femtosecond laser can be executed to modify the quartz glass.

And 5: and (4) carrying out ultrasonic-assisted chemical etching. And (4) placing the quartz glass modified by the femtosecond laser in the step (4) in a container filled with 5% HF solution, placing the container in an ultrasonic cleaning machine, setting the ultrasonic power to be 80W and the ultrasonic frequency to be 40kHz, and finishing the cutting of the quartz glass after ultrasonic-assisted chemical etching for 10 min.

Step 6: and (5) performing aftertreatment on the cut quartz glass. And respectively putting the cut fused quartz glass sample into pure water and absolute ethyl alcohol, cleaning for 5min by using an ultrasonic cleaning machine, and then drying by using nitrogen. Measuring the edge breakage size and the section steepness of the cut fused quartz glass by using a super-depth-of-field microscope; and measuring the roughness of the cross section of the sample, and characterizing by using an optical surface profiler.

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